U.S. patent application number 10/871902 was filed with the patent office on 2005-01-06 for medical implants and methods for regulating the tissue response to vascular closure devices.
This patent application is currently assigned to Vascular Therapies LLC. Invention is credited to Iyer, Sriram, Kipshidze, Nicholas, Nikolaychik, Victor, Roubin, Gary.
Application Number | 20050004158 10/871902 |
Document ID | / |
Family ID | 33539222 |
Filed Date | 2005-01-06 |
United States Patent
Application |
20050004158 |
Kind Code |
A1 |
Iyer, Sriram ; et
al. |
January 6, 2005 |
Medical implants and methods for regulating the tissue response to
vascular closure devices
Abstract
Devices and methods for reducing, eliminating, preventing,
suppressing, or treating tissue responses to hemostatic devices
e.g., biological sealants or vascular procedures are disclosed. The
invention employs a combination of resorbable, biocompatible matrix
materials and a variety of therapeutic agents, such as
antiproliferatives or antibiotics, applied to a vascular puncture
or incision to achieve hemostasis following diagnostic or
interventional vascular catheterizations and to treat neointimal
hyperplasia and stenosis. A matrix of a material such as collagen
provides a reservoir of a therapeutic agent such as rapamycin
(sirolimus) and its derivatives and analogs for delivery at a
tissue site at risk for vasculoproliferation, infection,
inflammation, fibrosis or other tissue responses.
Inventors: |
Iyer, Sriram; (New York,
NY) ; Kipshidze, Nicholas; (New York, NY) ;
Nikolaychik, Victor; (Thiensville, WI) ; Roubin,
Gary; (Jackson, WY) |
Correspondence
Address: |
MAYER, BROWN, ROWE & MAW LLP
190 SOUTH LASALLE ST
CHICAGO
IL
60603-3441
US
|
Assignee: |
Vascular Therapies LLC
New York
NY
|
Family ID: |
33539222 |
Appl. No.: |
10/871902 |
Filed: |
June 18, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10871902 |
Jun 18, 2004 |
|
|
|
10765005 |
Jan 26, 2004 |
|
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60479789 |
Jun 19, 2003 |
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Current U.S.
Class: |
514/291 |
Current CPC
Class: |
A61B 17/0057 20130101;
A61K 9/7007 20130101; A61K 31/4745 20130101; A61B 2017/00893
20130101; A61L 31/125 20130101; A61L 31/146 20130101; A61L 2300/416
20130101; A61B 2017/00641 20130101; A61P 9/10 20180101; A61L 31/044
20130101; A61B 2017/00659 20130101; A61L 31/16 20130101; A61K
31/436 20130101 |
Class at
Publication: |
514/291 |
International
Class: |
A61K 031/4745 |
Claims
We claim:
1. A method of treating a site of vascular compromise to seal a
puncture or opening, and to treat, suppress or prevent a tissue
response at such site, comprising the steps of: combining a tissue
response regulating amount of a therapeutic agent and a hemostatic
device or material; and applying the combination to the site.
2. The method of claim 1, wherein the therapeutic agent comprises a
compound of formula I: 2wherein R.sup.1 is hydrogen,
alkoxyhydroxyl, alkylalkoxycarbamoyl, tetrazolyl, or --OR.sup.14
wherein R.sup.14 is hydrogen, alkyl, alkenyl, alkynyl, aryl,
arylalkyl, thioalkyl, hydroxyalkyl, hydroxyaryl, hydroxyarylalkyl,
hydroxyalkoxyalkyl, hydroxyalkylarylalkyl, dihyroxyalkyl,
dihyroxyalkylarylalkyl, alkoxyalkyl, acyloxyalkyl,
alkylcarbonyloxyalkyl, aminoalkyl, alkylaminoalkyl,
alkoxycarbonylaminoalkyl, alkylcarbonylaminoalkyl,
arylsulfonamidoalkyl, allyl, dihyroxyalkylallyl, dioxolanylallyl,
carbalkoxyalkyl, or alkylsilyl, hydroxyl, carboxyl, cyano, halogen,
epoxy, sulfohalo, sulfoalkyl, sulfoaryl, sulfoarylalkyl,
sulfoheterocyclic, sulfoheterocyclicalkyl, sulfoamidoalkyl,
sulfoamidoaryl, oxoalkyl, oxoaryl, oxocycloalkyl, oxoarylalkyl,
oxoheterocyclic, oxoheterocyclicalkyl, carboxyl, carboxycycloalkyl,
carboxyaryl, carboxyheterocyclic, carboxy(N-succinimidyl),
alkylalkoxycarbonyl, carbamoylalkyl, alkylcarbamoylalkyl,
carbamoylalkenyl, carbamoylalkynyl, alkoxycarbamoyl,
carbamoylcycloalkyl, --N.sub.3, or
--R.sup.18--R.sup.15--R.sup.16--R.sup.17 wherein R.sup.18 is oxo,
alkyl, or amidoalkyl, R.sup.15 is nitrogen, and R.sup.16 and
R.sup.17 are independently selected from hydrogen, alkyl, alkenyl,
alkynyl, alkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, hydroxyl,
carboxyl, cyano, aryl, heterocyclic, and arylalkyl; R.sup.2 is
hydrogen, halogen, hydroxyl, alkyl, alkenyl, alkynyl, aryl, acyl,
acyloxy, aryloxy, alkylthio, alkylsulfinyl, oxo, or together with
R.sup.14 forms C.sub.2-6 alkylene; R.sup.3, R.sup.5, R.sup.7,
R.sup.9, and R.sup.10 are independently selected from hydrogen,
halogen, hydroxyl, alkyl, alkenyl, alkynyl, aryl, acyl, acyloxy,
aryloxy, alkylthio, alkylsulfinyl, and oxo; R.sup.4 is hydrogen,
hydroxyl, oxo, diazo, phenyl-substituted alkyl, .dbd.CH.sub.2,
--O--(CH.sub.2).sub.2--O--, --S--(CH.sub.2).sub.2--S--,
--O--(CH.sub.2).sub.3--O--, --S--(CH.sub.2).sub.3--S--, or
.dbd.N--N(R.sup.19)(R.sup.20) wherein R.sup.19 and R.sup.20 are
independently selected from hydrogen, alkyl aryl, arylalkyl,
heterocyclic, and heterocyclicalkyl; R.sup.6 is hydrogen, hydroxyl,
oxo, phenyl-substituted alkyl, --OR.sup.21 wherein R.sup.21 is
C.sub.14 alkyl, alkylcarbonyl, arylcarbonyl, heteroarylcarbonyl,
hydroxyalkylcarbonyl, aminoalkylcarbonyl, formyl, or aryl; R.sup.8
is alkoxy, oxo, --OR.sup.13, --S(O)--R.sup.13 or --NR.sup.13
wherein R.sup.13 is hydrogen, aryl, alkyl, alkenyl, alkynyl,
hydroxyalkyl, hydroxyalkenyl, hydroxyalkynyl, benzyl, alkoxybenzyl,
or chlorobenzyl and x is 0, 1, or 2; and R.sup.11 and R.sup.12 are
--CH.sub.2--, --S--, or >S.dbd.O.
3. The method of claim 1 wherein the therapeutic agent is
rapamycin.
4. The method of claim 1, wherein the therapeutic agent is an
analogue of rapamycin.
5. The method of claim 1, wherein the therapeutic agent is
everolimus.
6. The method of claim 1, wherein the therapeutic agent is
dexamethasone.
7. The method of claim 1, wherein the therapeutic agent is
paclitaxel.
8. The method of claim 1, wherein the therapeutic agent is
tacrolimus.
9. The method of claim 1, wherein the hemostatic material comprises
collagen.
10. The method of claim 9, wherein the collagen is Type I Bovine
collagen.
11. The method according to claim 9, wherein the collagen is
selected from the group consisting of Type I, Type II, Type II,
Type IV, Type XI, and mixtures thereof.
12. The method of claim 1, wherein the hemostatic material
comprises fibrin.
13. The method of claim 1, wherein the hemostatic material
comprises a polysaccharide.
14. The method of claim 13, wherein the polysaccharide is
chitosan.
15. The method of claim 1, wherein the hemostatic material is
selected from the group consisting of collagen, fibrin, chitosan
and mixtures thereof.
16. The method according to 9-15, wherein the hemostatic material
is biodegradable.
17. The method according to 9-15, wherein the hemostatic device is
non-biodegradable.
18. The method according to claim 1, wherein the hemostatic device
comprises an adjuvant.
19. The method according to claim 18, wherein the adjuvant inhibits
calcification.
20. The method according to claim 18, wherein the adjuvant is
Vitamin K.
Description
RELATED APPLICATIONS
[0001] This is a continuation-in-part application of U.S. patent
application Ser. No. 10/765,005 filed Jan. 26, 2004, which is a
continuation of Ser. No. 10/051,708 filed on Jan. 16, 2002, which
claimed priority to U.S. Provisional patent application Ser. No.
60/262,132 filed on Jan. 16, 2001. This application further claims
priority to U.S. Provisional Patent Application Ser. No. 60/479,789
filed Jun. 19, 2003. All such applications are incorporated herein
by reference to the extent permitted by law.
BACKGROUND
[0002] The present invention relates generally to therapeutic
implants, devices, and methods useful for preventing, suppressing,
or treating failure of hemodialysis vascular access grafts and
other vascular procedures. The invention also relates to
therapeutic implants comprising a matrix material and a therapeutic
agent, wherein the composition placed in external contact with a
blood vessel (perivascular implant of the composition) can be used
to achieve hemostasis, e.g., to seal a breach in the vascular wall
and to deliver a therapeutic agent capable of regulating the amount
of tissue response to the implanted matrix.
[0003] Vascular procedures such as construction of hemodialysis
access grafts and angioplasty are performed to provide vascular
access in patients with renal failure in need of hemodialysis
dysfunction and treat conditions such as atherosclerosis.
Hemodialysis vascular access grafts can be constructed as an
arterio-venous fistula (e.g., Brecisa-Cimino), or as a graft
interposing either prosthetic material (e.g.,
polytetrafluoroethylene "PTFE") or biological tissue (e.g., vein)
between an artery and a vein.
[0004] Such grafts are usually constructed using a tubular or
cylindrical segment of suitably biocompatible and substantially
inert material such as PTFE, the most common material used for
prosthetic dialysis access. In one approach, a segment of PTFE is
surgically interposed between an artery and a vein in the arm,
forearm, or thigh. The graft is then available for repeated
vascular access in performing hemodialysis.
[0005] Subsequent to placement of the graft, the sutured sites in
the artery and the vein undergo healing. However, 60 percent of
these grafts fail, usually because of luminal narrowing, or
stenosis, at the venous end. Similar lesions develop in synthetic
PTFE grafts placed in the arterial circulation, although stenosis
in arterial grafts develops slower than at venous ends. Failure or
dysfunction of grafts used in coronary artery bypass surgery or
peripheral vascular surgery (e.g., aorta-iliac, femoral-femoral,
femoral-popliteal, femoral tibial) is well known. Failure of
vascular grafts or arterial reconstruction results from luminal
narrowing of the vessel or prosthetic conduit, at or away from the
anastamotic site, from intraluminal thrombus or a
vasculoproliferative response, or from other pathologies, for
example, infection of the prosthetic graft.
[0006] Neointimal hyperplasia, a manifestation of the
vasculoproliferative response, affects the vessel and adjacent
graft orifice. The vessel wall thickens and the lumen narrows due
to migration and proliferation of smooth muscle cells. The etiology
of graft failures may relate to a variety of physical (e.g., shear
stress causing hemodynamic disturbance), chemical, or biological
stimuli, as well as infection or foreign body rejection, which may
explain why fistulae that do not involve a foreign body (e.g.,
PTFE) remain patent longer than vascular access grafts that involve
interposition of a PTFE graft. As the stenosis in the graft becomes
progressively more severe, the graft becomes dysfunctional and
access for medical procedures suboptimal. Left untreated, stenosis
eventually leads to occlusion and graft failure.
[0007] The venous ends of grafts are prone to narrowing for
multiple reasons. This location is uniquely exposed to arterial
pressures and arterial flow rates, dissipation of acoustic or
vibratory energy in the vessel wall and surrounding tissue,
repeated puncture of the graft, and infusion of processed blood. In
addition, in the hemodialysis example, the venous end of the graft
may be bathed in mitogens released during passage of the blood
through the dialysis tubing or during activation of platelets at
the site of needle puncture.
[0008] Tissue samples collected from the graft-vein anastomosis
site of stenotic PTFE grafts during surgical revision show
significant narrowing of the lumen and are characterized by the
presence of smooth muscle cells, accumulation of extracellular
matrix, angiogenesis within the neointima and adventitia, and
presence of an active macrophage cell layer lining the PTFE graft
material. A large variety of cytokines and cell growth stimulating
factors like platelet-derived growth factor (PDGF), basic
fibroblast growth factor (bFGF), and vascular endothelial growth
factor (VEGF) are expressed by smooth muscle cells or
myofibroblasts within the venous neointima, macrophages lining both
sides of the PTFE graft, and vessels within the neointima and
adventitia. Macrophages, specific cytokines (PDGF, bFGF, and VEGF),
and angiogenesis within the neointima and adventitia have been
suggested as likely contributing to the pathogenesis of venous
neointimal hyperplasia.
[0009] In the hemodialysis example, venous neointimal hyperplasia
characterized by stenosis and subsequent thrombosis accounts for
the overwhelming majority of pathology resulting in PTFE dialysis
graft failure, which prevents hemodialysis, leading to renal
failure, clinical deterioration, and death. Vascular access
dysfunction is the most important cause of morbidity and
hospitalization in the hemodialysis population. Despite the
magnitude of the problem and associated costs, however, no
effective therapies currently exist for the prevention or treatment
of venous neointimal hyperplasia in PTFE dialysis grafts.
[0010] Once stenosis has occurred, the treatment consists of
further vascular reconstruction. One current method of treatment
involves reduction or obliteration of the narrowing and restoration
of bloodflow through the graft by non-surgical, percutaneous
catheter-based treatments such as balloon angioplasty. This
procedure involves deploying a balloon catheter at the site of the
blockage and inflating the balloon to increase the minimum luminal
diameter of the vessel by compressing the material causing the
restriction against the interior of the vessel wall. Depending upon
the length and severity of the restriction, the procedure may be
repeated several times by inflating and deflating the balloon. When
completed, the balloon catheter is withdrawn from the system.
[0011] Although balloon angioplasty can be used as a "stand alone"
procedure, it is frequently accompanied by deployment of a stent. A
stent is an expandable scaffolding or support device that is placed
within the vasculature to prevent mechanical recoil and to reduce
the chance of renarrowing, or restenosis, at the site of the
original restriction. Stents are either "balloon-expandable" or
"self-expanding" and when deployed endovascularly, abut against the
inner vessel wall. Whether or not a stent is placed, this form of
treatment has a high risk of failure, i.e., a high risk of
restenosis at the treatment site. Unless stenosis can be
effectively and permanently treated, graft failure tends to
follow.
[0012] In the event of graft failure, the patient must undergo an
endovascular procedure, i.e., a non-surgical, catheter-based
percutaneous procedure or repeat vascular surgery such as
thrombectomy to "declot" the graft or to place another vascular
access graft or a shunt at a different site, unless the patient
receives a kidney transplant. Given the obvious problems of repeat
surgeries and the limited availability of transplants, treatment
that is both effective and durable in preventing and treating
stenosis is needed.
[0013] The vast majority of current approaches for treating the
vasculoproliferative response believed to be the pathophysiological
basis of stenosis and restenosis is based on treating from within
the vascular or graft lumen. One current approach utilizes
drug-coated or drug-impregnated stents that are deployed within the
lumen of the vessel. Examples of drugs used to coat stents include
rapamycin (sirolimus or Rapamune.RTM.) commercially available from
Wyeth (Collegeville, Pa.) and paclitaxel (Taxol.RTM.) commercially
available from Bristol-Myers Squibb Co. (New York, N.Y.). In this
stent-based approach, rapamycin or paclitaxel gradually elutes from
the stent and diffuses into the vessel wall from the intima, the
innermost layer of the vessel wall, to the adventitia, the
outermost layer of the vessel wall. Studies have shown that
rapamycin and paclitaxel tend to inhibit smooth muscle cell
proliferation.
[0014] Delivery of drugs from the perivascular or extravascular
space through the vascular wall, by utilizing a synthetic matrix
material (ethylene-vinyl acetate copolymer) together with an
anticoagulant that also has antiproliferative properties, e.g.,
heparin, has been suggested. However, this approach has two
disadvantages. Heparin is soluble and rapidly disappears from the
vascular wall, and ethylene-vinyl acetate copolymer is not
biodegradable, potentially raising concerns about long term effects
in vivo.
[0015] To effectively deliver a therapeutic agent locally using a
matrix material-based system, the matrix material should preferably
have certain characteristics. The matrix material should permit the
loading of adequate quantity of the therapeutic agent. The matrix
material should elute the therapeutic agent at an appropriate,
well-defined rate. The matrix material should preferably be
implantable and biodegradable, so as to not require physical
removal of the matrix material from the recipient's tissue
following drug delivery and to obviate concerns about long term
effects of the residual matrix.
[0016] Furthermore, the matrix material and its biodegradation
products should not provoke a significant inflammatory or
proliferative tissue response and should not alter or interfere
with the recipient's natural defense systems or healing. The device
comprising the matrix material and the therapeutic agent should be
flexible enough to mould to the contours of the vasculature. The
device should also be amenable to being fixed in place, such that
it does not migrate to an unintended location.
[0017] Polymer matrix materials used for drug delivery within the
context of implantable devices can be either natural or synthetic.
Examples include but are not limited to polymers composed of
chemical substances like polyglycolic acid, polyhydroxybutyrate,
ethylene-vinyl acetate, or natural polymers like collagen and
fibrin, or polysaccharides such as chitosan. Matrix materials with
poor mechanical characteristics, potential immunogenicity, toxic
degradation products, inflammatory properties, or a tendency to
induce a proliferative response would be inappropriate.
[0018] A well-known biocompatible, biodegradable, resorbable matrix
material for drug delivery is collagen. The use of collagen as a
material for fabrication of biodegradable medical devices has
undergone serious scrutiny (U.S. Pat. Nos. 6,323,184; 6,206,931;
4,164,559; 4,409,332; 6,162,247). One current approach using
collagen involves delivery of pharmaceutical agents, including
antibiotics and physiologically active proteins and peptides such
as growth factors. Effective delivery of any therapeutic agent
should also preferably not interfere with the natural healing
process.
SUMMARY OF THE INVENTION
[0019] The present invention relates to devices and methods for
preventing, suppressing, or treating the vasculoproliferative
response to vascular procedures or devices. In one embodiment, the
invention prevents, suppresses, or treats vasculoproliferative
disease by delivering one or more therapeutic agents from outside
the vasculature and through the vascular wall. The invention may be
advantageously used before stenosis has occurred or to treat
established neointimal hyperplasia, or to prevent fibrous tissue
after incisions.
[0020] Another aspect of this invention is directed to methods for
reducing, eliminating or prophylactically treating the tissue
response that accompanies the perivascular placement of a synthetic
or biological matrix (e.g., collagen), suture, staple, clip or
other form of prosthetic device for sealing the punctures in blood
vessels, (artery or vein). Such matrices referred to as vascular
closure devices are typically used to achieve hemostasis at
point(s) of entry into the vascular system such as those that occur
following percutaneous diagnostic and interventional cardiac,
carotid and peripheral vascular catheterizations.
[0021] Although the perivascular placement of the matrix (e.g.,
collagen matrix) is effective in sealing the point of vascular wall
breach thereby achieving hemostasis, the biodegradable collagen
matrix can provoke tissue response(s) that can potentially envelop
the blood vessel at the site of placement of the matrix. Such
tissue response(s) may increase the morbidity of the vascular
closure device, may render palpation of the arterial pulse (a
helpful clinical pre-requisite for obtaining future vascular
access) more difficult and make future percutaneous access at or
through the placement of such matrices more difficult. By combining
a therapeutic agent or agents to the collagen matrix, it is an
object of the present invention to provide a method and a
composition for reducing the host response to the perivascular
collagen matrix vascular sealant applied to the wall of an arterial
or venous puncture site.
[0022] One embodiment of the invention comprises a device composed
of a resorbable, biocompatible matrix combined with at least one
therapeutic agent. The device may optionally further comprise
pharmaceutically acceptable adjuvants or additives. The device may
be placed on the outer surface of a vessel to elute a tissue
response regulating amount of a therapeutic agent, such as an agent
that inhibits smooth muscle cell proliferation. The biocompatible
matrix creates a reservoir of the therapeutic agent and controls
the delivery kinetics.
[0023] In one-embodiment, the biocompatible matrix is a
biodegradable layer of collagen, with an optional exterior support
structure or layer of PTFE and imbibed with one or more therapeutic
agents, such as rapamycin. This therapeutic agent imbibed matrix
may be made more adhesive to the vascular wall by combining the
matrix with fibrin sealant, acetylated collagen, or photoreactive
groups that can be stimulated by ultraviolet light.
[0024] Yet another aspect of the present invention comprises a
method for reducing, eliminating or prophylactically treating the
host response to the perivascularly applied collagen matrix
(sealant) or hemostatic device. The hemostatic device may be
biological, polymer based or mechanical. When placed at a site of
vascular puncture or incision, the matrix, besides functioning as a
sealant at the site of the vascular pucture site, incision site or
site of vascular breach, allows for gradual elution of the
therapeutic agent and serves as an extravascular source of drug
delivery. Elution of the therapeutic agent such as rapamycin into
and through the vascular wall occurs during the healing of
anastamotic sites to prevent, suppress, or treat smooth muscle cell
proliferation or other tissue responses to the vascular
procedure.
[0025] Host responses to the implanted foreign body material may
include, for example, infection and inflammation. Accordingly a
variety of therapeutic agent (s) may be added (singly or in
combination) to the collagen matrix. Examples of therapeutic agents
that could be added include anti-proliferative agents, like
rapamycin, tacrolimus and paclitaxel, anti-inflammatory (e.g.,
NSAIDS) hormones (e.g., estrogen) and antibiotics.
[0026] In particular, the method comprises the steps of: combining
the therapeutic agent(s) with the matrix (e.g., collagen matrix)
and placing the therapeutic agent imbibed sleeve perivascularly so
as to cover the site of vascular access with anticipation of the
local release of the drug(s).
[0027] In addition to having application in sealing puncture sites
associated with cardiac and vascular catheterization procedures,
the present invention is deemed useful and applicable to various
diagnostic and therapeutic interventional procedures including
atherectomies, stent implantation, rotablators, thrombolysis
therapy, laser angioplasty, valvuloplasty, aortic prosthesis
implantation, intraortic balloon pumps, pacemaker implantation and
electrophysiology studies as well as in patients with congenital
heart disease and those undergoing dialysis and procedures relating
to percutaneous extracorporeal circulation. The present invention
may be used in both adults and children independent of the age of
the vessel to be sealed.
[0028] The inventive method may be practiced with any embodiment of
a device suitable for delivery of therapeutic agents to regulate
the tissue response to vascular procedures or devices. In one
embodiment, the device is a sheet of matrix material such as
collagen cylindrically shaped to fit over a vessel at the site of
puncture or incision like a sleeve, to deliver therapeutic agents
extravascularly. The sleeve may be secured to the vessel by
sutures, self-adhesion, or stabilized over the vessel by suturing
the free edges of the sleeve to one another thereby providing a
snug fit over the vessel wall.
[0029] In another embodiment, the device may be constructed to
deliver a plug of hemostatic material imbibed with a therapeutic
agent, to seal a puncture or incision or other breach of the vessel
wall. In yet another embodiment, the device may be used to envelop
a puncture site, incision or other breach of the vessel wall from
the interior, interior and exterior and/or exterior of the vessel.
The device comprises a tissue response regulating amount of a
therapeutic agent and a biological sealant or hemostatic
device.
BRIEF DESCRIPTION OF FIGURES
[0030] FIGS. 1A, 1B, 2A, and 2B illustrate preferred embodiments of
the present invention;
[0031] FIGS. 2A and 2B illustrate another embodiment of the present
invention in which an exterior support or skeletal structure is
employed;
[0032] FIGS. 3A-3C illustrate a self-interlocking embodiment of
this invention;
[0033] FIG. 4 illustrates another example of a self-interlocking
design of the present invention;
[0034] FIG. 5 shows the basic device shown in FIGS. 1A, 1B, 2A, and
2B including an exterior wire support or framework, which assists
retention of sleeve shape;
[0035] FIGS. 6-13 illustrate various possible deployments of the
drug-eluting sleeve of the present invention in view of various
vessel reparative needs;
[0036] FIG. 14 shows rates of release of collagen saturated with
rapamycin (sirolimus) and tetracycline;
[0037] FIG. 15 is a comparison of inhibition of growth of smooth
muscle cells using collagen matrices combined with different
antiproliferative agents;
[0038] FIG. 16 is a comparison of the effect of paclitaxel (3
doses), rapamycin (sirolimus), and tacrolimus on human smooth
muscle cells;
[0039] FIG. 17 is a comparison of the effect of paclitaxel (3
doses), rapamycin (sirolimus), and tacrolimus on human endothelial
cells;
[0040] FIGS. 18A, 18B, 19A, 19B, and 20 illustrate some results
obtained using the present invention;
[0041] FIG. 21 illustrates an embodiment of the invention as a plug
device;
[0042] FIG. 22 illustrates an alternative embodiment of the plug
device, detailed distally;
[0043] FIG. 23 illustrates an embodiment of the invention as an
anchor device, detailed distally;
[0044] FIG. 24 illustrates the anchor device when deployed;
[0045] FIG. 25 illustrates an embodiment of the invention as a
sandwich device, detailed distally; and
[0046] FIG. 26 illustrates the sandwich device when deployed.
DETAILED DESCRIPTION
[0047] The medical devices of the present invention broadly
comprise one or more therapeutic agents imbibed in one or more
biocompatible matrices. In one aspect, the present invention is a
sleeve comprising a therapeutic agent eluting matrix material
combined with a therapeutic agent that can be delivered
extravascularly to prevent, suppress, or treat
vasculoproliferation.
[0048] In another aspect, the present invention is a matrix
material combined with a therapeutic agent, the composition in the
form of a plug, wherein the plug can be used to seal a vascular
puncture site and to deliver a tissue response regulating amount of
a therapeutic agent. In yet another aspect, the present invention
provides an anchoring device for the therapeutic agent imbibed
matrix. In a further aspect, the present invention forms a
"sandwich" configuration around a vascular puncture, to close the
puncture intravascularly as well as extravascularly and to deliver
therapeutic agents.
A. THERAPEUTIC AGENTS
[0049] The therapeutic agents that may be added to the matrix
material include a substance selected from a group consisting of
anti-inflammatory drugs, smooth muscle cell growth inhibitors,
endothelial cell stimulators, antineoplastic reagents, antibiotics,
blood clotting inhibitors, genetic material, and mixtures thereof.
As used herein, "anti-inflammatory drug" refers to a substance that
reduces inflammation by acting on body mechanisms. "Stimulator of
endothelial cell growth" refers to a substance that stimulates the
growth and/or attachment and/or chemotaxis of endothelial cells.
"Antineoplastic reagent" refers to any substance preventing or
arresting the development, maturation, or spread of neoplastic
cells. "Antibiotic" refers to a soluble substance derived either
naturally from a mold or bacteria or synthetically that inhibits
the growth of microorganisms.
[0050] The term "therapeutic agent" means any agent possessing
pharmacological activity in preventing, suppressing, or treating
the smooth muscle cell proliferation involved in neointimal
hyperplasia, stenosis, restenosis, or failure of vascular grafts or
procedures, or any agent that regulates tissue response. The agent
may, if desired, be in the form of a free base, a free acid, a
salt, an ester, a hydrate, an amide, an enantiomer, an isomer, a
tautomer, a prodrug, a polymorph, a derivative, an analogue, or the
like, provided that the free base, free acid, salt, ester, hydrate,
amide, enantiomer, isomer, tautomer, prodrug, polymorph,
derivative, or analogue is suitable pharmacologically, i.e.,
effective in the present methods, compositions, and devices.
[0051] 1. Antiproliferative Agents
[0052] Examples of therapeutic agents with actions that include
inhibition of smooth muscle cell or fibroblast growth (one aspect
of an antiproliferative effect) include, but are not limited to,
acetylsalicylic acid (aspirin), actinomycin D, angiopeptin,
angiostatin, azathioprine, brequinar sodium, cisplatin, cyclosporin
A, desferoxamine, deoxyspergualin, endostatin, enoxaprin, estrogen,
flavoperidol, fluorouracil, halofuginone, hirudin, matrix
metalloproteinase inhibitors, mizaribine, mitoguazone, mycophenolic
acid morpholino ester, paclitaxel, taxanes, epothilones,
raloxifene, rapamycin (sirolimus), analogues of rapamycin,
everolimus, ABT 578, Biolimus, tacrolimus (FK506), vinblastine,
vincristine, vitamin K, nitric oxide donors such as
nitrosoglutathione, substrates for nitric oxide production such as
L-arginine, and derivatives and mixtures thereof.
[0053] Derivatives of these compounds may also be used, e.g.,
40-O-(2-hydroxy)ethylrapamycin or everolimus, a structural
derivative of rapamycin (sirolimus), also known as SDZ-RAD (Serkova
et al., Br. J. Pharmacol. (2001) 133: 875-885; Hausen et al.,
Transplantation (2000) 69: 76-86); other analogues of rapamycin
(sirolimus) such as ABT-578, CCI-779, 7-epitrimethoxyphenyl
rapamycin, 7-thiomethyl rapamycin, 7-epirapamycin, 7-epi-thiomethyl
rapamycin, 7-demethoxy rapamycin, 30-demethoxy rapamycin,
27-desmethyl rapamycin, and 26-dihydro rapamycin,
33-deoxo-33-(R)-hydroxyrapamycin; and the estrogen derivative
17.beta.-estradiol.
[0054] Therapeutic agents with antiproliferative effects useful in
the methods, compositions, and devices of the present invention
include substituted macrocyclic compounds with antiproliferative
activity, including a substituted compound of Formula I: 1
[0055] wherein R.sup.1 is hydrogen, alkoxyhydroxyl,
alkylalkoxycarbamoyl, tetrazolyl, or --OR.sup.14 wherein R.sup.14
is hydrogen, alkyl, alkenyl, alkynyl, aryl, arylalkyl, thioalkyl,
hydroxyalkyl, hydroxyaryl, hydroxyarylalkyl, hydroxyalkoxyalkyl,
hydroxyalkylarylalkyl, dihyroxyalkyl, dihyroxyalkylarylalkyl,
alkoxyalkyl, acyloxyalkyl, alkylcarbonyloxyalkyl, aminoalkyl,
alkylaminoalkyl, alkoxycarbonylaminoalkyl, alkylcarbonylaminoalkyl,
arylsulfonamidoalkyl, allyl, dihyroxyalkylallyl, dioxolanylallyl,
carbalkoxyalkyl, or alkylsilyl, hydroxyl, carboxyl, cyano, halogen,
epoxy, sulfohalo, sulfoalkyl, sulfoaryl, sulfoarylalkyl,
sulfoheterocyclic, sulfoheterocyclicalkyl, sulfoamidoalkyl,
sulfoamidoaryl, oxoalkyl, oxoaryl, oxocycloalkyl, oxoarylalkyl,
oxoheterocyclic, oxoheterocyclicalkyl, carboxyl, carboxycycloalkyl,
carboxyaryl, carboxyheterocyclic, carboxy(N-succinimidyl),
alkylalkoxycarbonyl, carbamoylalkyl, alkylcarbamoylalkyl,
carbamoylalkenyl, carbamoylalkynyl, alkoxycarbamoyl,
carbamoylcycloalkyl, --N.sub.3, or
--R.sup.18--R.sup.15--R.sup.16--R.sup.17 wherein R.sup.18 is oxo,
alkyl, or amidoalkyl, R.sup.15 is nitrogen, and R.sup.16 and
R.sup.17 are independently selected from hydrogen, alkyl, alkenyl,
alkynyl, alkoxy, cycloalkyl, cycloalkenyl, cycloalkynyl, hydroxyl,
carboxyl, cyano, aryl, heterocyclic, and arylalkyl;
[0056] R.sup.2 is hydrogen, halogen, hydroxyl, alkyl, alkenyl,
alkynyl, aryl, acyl, acyloxy, aryloxy, alkylthio, alkylsulfinyl,
oxo, or together with R.sup.14 forms C.sub.2-6 alkylene;
[0057] R.sup.3, R.sup.5, R.sup.7, R.sup.9, and R.sup.10 are
independently selected from hydrogen, halogen, hydroxyl, alkyl,
alkenyl, alkynyl, aryl, acyl, acyloxy, aryloxy, alkylthio,
alkylsulfinyl, and oxo;
[0058] R.sup.4 is hydrogen, hydroxyl, oxo, diazo,
phenyl-substituted alkyl, .dbd.CH.sub.2,
--O--(CH.sub.2).sub.2--O--, --S--(CH.sub.2).sub.2--- S--,
--O--(CH.sub.2).sub.3--O--, --S--(CH.sub.2).sub.3--S--, or
.dbd.N--N(R.sup.19)(R.sup.20) wherein R.sup.19 and R.sup.20 are
independently selected from hydrogen, alkyl aryl, arylalkyl,
heterocyclic, and heterocyclicalkyl;
[0059] R.sup.6 is hydrogen, hydroxyl, oxo, phenyl-substituted
alkyl, --OR.sup.21 wherein R.sup.21 is C.sub.1-4 alkyl,
alkylcarbonyl, arylcarbonyl, heteroarylcarbonyl,
hydroxyalkylcarbonyl, aminoalkylcarbonyl, formyl, or aryl;
[0060] R.sup.8 is alkoxy, oxo, --OR.sup.13, --S(O).sub.xR.sup.13 or
--NR.sup.13 wherein R.sup.13 is hydrogen, aryl, alkyl, alkenyl,
alkynyl, hydroxyalkyl, hydroxyalkenyl, hydroxyalkynyl, benzyl,
alkoxybenzyl, or chlorobenzyl and x is 0, 1, or 2; and
[0061] R.sup.11 and R.sup.12 are --CH.sub.2--, --S--, or
>S.dbd.O. 2. Antibiotic Agents
[0062] Antibiotics are used to prevent infection after implantation
of the matrix. Preferred antibiotics include, but are not limited,
to all broad and medium spectrum agents, including penicillins,
aminoglycolides, cephalosporins (1st, 2nd, and 3rd generation),
macrolides (rapamycin, for example, is a macrolide antibiotic),
tetracyclines, and derivatives and mixtures thereof. Such
therapeutic agents and all analogues, derivatives, isomers,
polymorphs, enantiomers, salts, and prodrugs thereof may be used in
the present invention.
[0063] 3. Anti-Inflammatory Agents
[0064] Examples of therapeutic agents with anti-inflammatory
effects include, but are not limited to, acetylsalicylic acid
(aspirin), angiopoietin-1, atorvastatin, rapamycin, analogues of
rapamycin, steroids (e.g., dexamethasone), non-steroidal
anti-inflammatory agents like indomethacin, COX.sub.2 inhibitors
(see Merck Index (13th Ed.). Such therapeutic agents and all
analogues, derivatives, isomers, polymorphs, enantiomers, salts,
and prodrugs thereof may be used in the present invention.
[0065] 4. Other Therapeutic Agents
[0066] Other therapeutic agents may be selected from the group
consisting of anticoagulants (e.g., heparin, hirudin, vitamin K),
direct thrombin inhibitors, antilipemic agents (e.g., atorvastatin,
cerivastatin, simvastatin, lovastatin), antimetabolites,
antineoplastic agents (e.g., cisplatin, methotrexate), antiplatelet
agents (e.g., clopidogrel, ticlopidine, diflunisal), antithrombins,
antirheumatics, calcium channel blockers, cells (e.g., bone barrow,
stem, vascular), corticosteroids, IIbIIIa antagonists,
immunomodulators, immunosuppressants (mycophenolate mofetil), and
recombinant DNA or proteins (list based in part on the Merck Index
(13th Ed.)). Specific compounds within each of these classes may
also be selected from any of those listed under the appropriate
group headings in Comprehensive Medicinal Chemistry, Pergamon
Press, Oxford, England (1990), pp. 970-986, the disclosure of which
is incorporated herein by reference.
[0067] Yet another additive is a stimulator of endothelial cell
growth. Preferred stimulators of endothelial cell growth include
basic fibroblast cell growth factor, endothelial cell growth
factor, alpha.sub.2 macroglobulin, vitronectin, fibronectin,
fibronectin fragments containing binding determinants for
endothelial cells, and derivatives and mixtures thereof. The
stimulator is generally used at pharmacological concentrations.
Specifically, fibronectin preferably has a concentration ranging
from about 5 to about 150 ng/ml.
[0068] Illustrative pharmaceutically acceptable salts are prepared
from formic, acetic, propionic, succinic, glycolic, gluconic,
lactic, malic, tartaric, citric, ascorbic, glucuronic, maleic,
fumaric, pyruvic, aspartic, glutamic, benzoic, anthranilic,
mesylic, stearic, salicylic, p-hydroxybenzoic, phenylacetic,
mandelic, embonic (pamoic), methanesulfonic, ethanesulfonic,
benzenesulfonic, pantothenic, toluenesulfonic,
2-hydroxyethanesulfonic, sulfanilic, cyclohexylaminosulfonic,
algenic, b-hydroxybutyric, galactaric, and galacturonic acids.
[0069] The present invention also includes prodrugs of the
therapeutic agents and their salts. The term "prodrug" refers to a
drug or compound in which the pharmacological action or active
curative agent results from conversion by metabolic processes
within the body. Prodrugs are generally considered drug precursors
that, following administration to a subject and subsequent
absorption, are converted to an active or a more active species via
some process, such as a metabolic process. Other products from the
conversion process are easily disposed of by the body.
[0070] Prodrugs generally possess a chemical group that renders
them less active or confers solubility or some other property to
the drugs. Cleaving of the chemical group generates the more active
drug. Prodrugs may be designed as reversible drug derivatives and
utilized as modifiers to enhance drug transport to site-specific
tissues. The design of prodrugs to date has been to increase the
effective water solubility of the therapeutic compound for
targeting to regions where water is the principal solvent (Fedorak,
et al., Am. J. Physiol. (1995), 269: G210-218, describing
dexamethasone-beta-D-glucuronide; McLoed, et al., Gastroenterol.
(1994), 106: 405-413, describing dexamethasone-succinate-d-
extrans; Hochhaus, et al., Biomed. Chrom. (1992), 6: 283-286,
describing dexamethasone-21-sulphobenzoate sodium and
dexamethasone-21-isonicotinate- ).
[0071] Prodrugs are also discussed in Sinkula et al., J. Pharm.
Sci. (1975), 64:181-210, in Higuchi, T. and Stella, V., Pro-Drugs
as Novel Delivery Systems, Vol. 14 of the A.C.S. Symposium Series,
and in Bioreversible Carriers in Drug Design (Ed. Edward B. Roche),
American Pharmaceutical Association and Pergamon Press (1987).
[0072] The present invention also includes derivatives of the
therapeutic agents. The term "derivative" refers to a compound that
is produced from another compound of similar structure by the
replacement or substitution of one atom, molecule, or group by
another. Salts, esters, hydrates, amides, enantiomers, isomers,
tautomers, prodrugs, polymorphs, derivatives, and analogues of the
pharmaceutical agents may be prepared using standard procedures
known to those skilled in the art of synthetic organic chemistry
and described, for example, in March, J., Advanced Organic
Chemistry: Reactions, Mechanisms and Structure (4.sup.th Ed.),
Wiley-Interscience, New York (1992).
[0073] The present invention can typically contain an amount of
therapeutic agent from about 0.001 .mu.g to about 200 .mu.g per mg
weight of the composition. The dose of the therapeutic composition
that is administered and the dosage regimen for treating the
condition or disease depend on a variety of factors, including the
age, weight, sex, and medical condition of the subject, the
severity of the condition or disease, the route and frequency of
administration, the time of administration, the rate of excretion,
any synergistic or potentiating activity of any combined agents,
and the specific activity of the agent, and can therefore vary
widely, as is well known.
[0074] Table 1 below lists some of the various therapeutic agents
contemplated in this invention.
1TABLE 1 Therapeutic Agents Alternative Names and Common or
Chemical Name References Rapamycin ((3S, 6R, 7E, 9R, 10R, 12R, 14S,
15E, 17E, 19E, Sirolimus; Rapamune .RTM.; Merck 21S, 23S, 26R, 27R,
34aS)- Index (13.sup.th Ed.), at monograph
9,10,12,13,14,21,22,23,24,25,26,27,32,33,34,34a- - 8202, p. 1454
hexadecahydro-9,27-dihydroxy-3-[(1R)-2[(1S,3R,4R)-4- -
hydroxy-3-methoxycyclohexyl]-1-methylethyl]10,21-
dimethoxy-6,8,12,14,20,26-hexamethyl-23,27-epoxy-3H-
pyrido[2,1-c][1,4] oxaazacyclohentriacontine-1,5,11,28,29
(4H,6H,31H)-pentone) Rapamycin 42-ester with
3-hydroxy-2-(hydroxymethyl)-2- CCI-779; WO 02/40000; U.S.
methylpropionic acid Pat. Pub. No. 20030050222
42-Epi-(tetrazolyl)-rapamycin ABT-578; U.S. Pat. No. 6,015,815;
U.S. Pat. Pub. No. 20030129215; U.S. Pat. Pub. No. 20030123505
4-Dimethylamino-but-2-enoic acid [4-(3-chloro-4-fluoro- EKB-569;
U.S. Pat. Pub. No.
phenylamino)-3-cyano-7-ethoxy-quinolin-6-yl]-amide 20030050222
40-O-(2-hydroxyethyl)-rapamycin Everolimus; SDZ-RAD; RAD001;
Certican; U.S. Pat. Pub. No. 20010041179; Eur. J. Cardiothorac.
Surg. 2003, 24: 154-158; Expert Opin. Investig. Drugs 2002, 11:
1845-57; N. Engl. J. Med. 2003, 349: 847-858 16-O-substituted
rapamycins WO 94/02136; WO 96/41807 40-O-substituted rapamycins WO
94/09010; WO 92/05179; WO 95/14023; WO 94/02136; WO 94/02385; WO
96/13273 20-Thiarapamycin Org. Lett. 2003, 5: 2385-2388
15-Deoxo-19-sulfoxylrapamycin Org. Lett. 2003, 5: 2385-2388
32-Deoxorapamycin SAR 943; Immunology 2003, 109: 461-467; Am. J.
Respir. Crit. Care Med. 2003, 167: 193-198
33-Deoxy-33-hydroxyrapamycin U.S. Pat. No. 5,138,051; U.S. Pat. No.
5,169,851; U.S. Pat. No. 5,202,332 Paclitaxel Merck Index
(13.sup.th Ed.), at monograph 7052, p. 1251
N-debenzoyl-N-(2-thenoyl) butitaxel J. Med. Chem. 1997, 40: 236-241
N-debenzoyl-N-tert-butoxycarbonyl-10-deacetyl taxol Taxotere;
Docetaxel; RP 56976; NSC 628503; Cancer Res. 1991, 51: 4845-4852;
J. Natl. Cancer Inst. 1991, 83: 288-291 Pimecrolimus U.S. Pat. Pub.
No. 20030170287; Eur. J. Dermatol. 2002, 12: 618-622 LF 15-0195
(analogue of 15-deoxyspergualin) Transplantation 2003, 76: 644-650
Sanglifehrin A J. Immunol. 2003, 171: 542-546 Mycophenolate mofetil
U.S. Pat. Pub. No. 20030181975; Transplantation 2003, 75: 54-59
Actinomycin D U.S. Pat. Pub. No. 20030181482; U.S. Pat. Pub. No.
20030181975 Acetylsalicylic acid Aspirin; Merck Index (13.sup.th
Ed.), at monograph 856, p. 145 Dexamethasone Merck Index (13.sup.th
Ed.), at monograph 2960, p. 518
[0075] 5. Synergism and Potentiation of Therapeutic Agents
[0076] In an embodiment of the present invention, two or more
therapeutic agents are combined with the matrix material to enhance
the pharmacological effect of the methods and devices of the
invention, synergistically or potentiationally to increase the
effect of one or more of the therapeutic agents. The therapeutic
agents may have similar or different pharmacological activities, be
combined in one matrix, be imbibed in separate matrix layers, or be
otherwise combined with the matrix as synergistically or
potentiationally advantageous for practicing the invention.
[0077] Isobolograms may be used to study the combined effects of
two pharmacological agents. Here, the concentration of each drug
alone that produces a certain endpoint (e.g., 50% inhibition of
cell growth) is plotted on the two graphical axes. The straight
line connecting the two points represents equally effective
concentrations of all combinations of the two drugs if the
interaction is purely additive. A shift of the isobologram to the
left of the predicted cytotoxicity (curve with concave side up)
represents a synergistic interaction.
[0078] Conversely, a shift to the right (curve with convex side up)
represents an antagonistic interaction. When isobolograms for
different endpoints are plotted on the same graph, the
concentration of each drug is expressed as the fraction of the
concentration of each drug alone that produced the same effect.
This produces a symmetrical isobologram with unit-less measures on
each axis and allows a direct comparison of different
endpoints.
B. BIOCOMPATIBLE MATRIX OR SEALANT
[0079] In the present invention, the matrix or sealant material (or
a "hemostatic device") creates a delivery depot or reservoir for
the therapeutic agent and controls the delivery kinetics. Material
for the matrix may be from natural sources or synthetically
manufactured, or a combination of the two. A device of this
invention may employ a biocompatible, biodegradable resorbable
matrix material such as chitosan, collagen, or fibrin. A suitably
biocompatible, nonbiodegradable matrix may also be used. Thus, a
combination of biodegradable and nonbiodegradable substances, two
or more biodegradable substances, or two or more nonbiodegradable
substances may be selected for the matrix material.
[0080] Important in the selection of a particular matrix material
is the porosity of the material and, where applicable, durability
or a controllable rate of biodegradation, as well as the ability to
interact with clotting factors in the blood and tissue to initiate
hemostasis. The porosity of the matrix influences the drug binding
and elution capacity. The durability of the matrix reflects the
time required for complete reabsorption of the matrix material and
also influences the drug delivery capacity, since as the matrix
material degrades, it elutes the drug. Both porosity and durability
can be controlled and varied as advantageous for practicing the
invention. The characteristics with respect to porosity, rate of
biodegradation, thickness, etc., need not be identical throughout
the matrix.
[0081] Collagen (Type I) is a preferred material for the matrix or
sealant of the drug eluting device of the present invention.
Collagen is biocompatible, biodegradable, resorbable, naturally
occurring, and non-toxic. Collagen exhibits a high degree of
flexibility and mechanical durability, as well as intrinsic water
wettability, semipermeability, and consistent flow characteristics.
In addition, collagen has favorable degradation or resorption
characteristics, and, as is well known in the art, the rate at
which resorption of the collagen occurs can be modified by
cross-linking the protein.
[0082] The collagen may be from an animal or a human source or
produced using recombinant DNA techniques. Any type of collagen,
e.g., Types II, III, V, or XI, alone or in combination with Type I,
may be used. Although collagen matrix in the form of a sheet, or
membrane, or plug is the preferred embodiment of this invention,
other forms of collagen, e.g., gel, fibrillar, sponge, tubular,
etc., may also be used. A collagen matrix in the form of a sheet or
membrane may be about 0.1-5mm thick and produced in a wide range of
effective pore sizes, from about 0.001-100 .mu.m or even larger.
This internal pore network creates a high surface area and serves
as a microreservoir for storage and delivery of a therapeutic
agent.
[0083] Another protein matrix or sealant suitable for drug delivery
is made of fibrin. A fibrin matrix is comprised of cross-linked
fibrin units that are a reticular network of thrombin-modified
fibrinogen molecules. This matrix is similar to a natural blood
clot. In contrast to a natural blood clot, however, the size of
pores in a fibrin matrix can be controlled and varies from about
0.001-0.004 m.mu. (millimicrons, so-called micropores). The
differences in pore sizes between collagen and fibrin matrices
permit the binding of therapeutic agents for distinct rates of drug
release. The ability to control bleeding, remain firmly fixed in
place, and naturally degrade makes fibrin a good matrix material
for drug delivery and confers some advantages over synthetic
matrices. Early applications of fibrin as a matrix have been for
delivery of antibiotics and other biologics.
[0084] Fibrin matrices are prepared in a dry granular form
(International Application No. PCT/EP99/08128). This formulation,
manufactured by HyQSolvelopment (Binzen, Germany; HyQ-Granuseal)
using fluid bed granulation, contains D-mannitol, D-sorbit,
fibrinogen-aqueous solution, and a thrombin-organic suspension. Dry
fibrin may be used in wound closure, promotion of healing, and
homeostasis. However, application of such a formulation in drug
delivery is limited because it does not allow for a target-oriented
shaping of solid particles around the vessel wall and delivery of
exact doses. Dry fibrin particles have low porosity and poor
physical stability.
[0085] Another potentially useful matrix or sealant material is
chitosan. Chitosan is a natural polymer and biodegradable. It has
proven to be a useful biocompatible aminopolysaccharide and a
matrix for controlled release of therapeutic agents for local
delivery. Chitosan implants cause no systemic and local side
effects or immunologic responses. Chitosan can be prepared from the
degradation of slow chitin (mol wt 1.times.10.sup.6) using high
temperature sodium hydroxide hydrolysis, to a molecular weight of
5.times.10.sup.5. However, the inability to control porosity is a
disadvantage of chitosan as matrix material.
C. OPTIONAL ADJUVANTS
[0086] A device of this invention optionally includes agents
(hereafter adjuvants) that accomplish other objectives, e.g., that
inhibit collagen accumulation and help reduce calcification of the
vascular wall. Early research has shown a relationship between
local vessel trauma and expedited calcification. Recently, a study
in humans has shown that the matrix Gla-protein (protein
y-carboxylated vitamin K-dependent .gamma.-carboxylase) is
constitutively expressed by normal vascular smooth muscle cells and
bone cells. High levels of Gla-protein mRNA and
non-.gamma.-carboxylated protein were found in atherosclerotic
vessel tissues.
[0087] This .gamma.-carboxylated protein is necessary to prevent or
postpone the onset of vascular calcification (Price et al.,
Arterioscler. Thromb. Vasc. Biol. (1998) 18: 1400-1407). These data
indicate that calcification caused by injury must be actively
inhibited. Introduction of pharmaceuticals that prevent calcium
accumulation helps to postpone calcification and the restenotic
processes.
[0088] In this invention, local delivery of vitamin K counteracts
the calcification effect associated with vessel injury, by timely
activation of .gamma.-carboxylase (in this case Gla-protein), and
ensures that other calcium-binding proteins function properly and
do not bind excess calcium (Hermann et al., Arterioscler. Thromb.
Vasc. Biol. (2000) 20: 2836-2893). A mixture of vitamin K along
with other antiproliferative drugs may be used.
[0089] The acute response to any injury, including surgical trauma,
characterized by an inflammatory reaction is an attempt to limit
disturbances in homeostasis. Hallmarks of this inflammatory
reaction include leukocyte accumulation, increased fibrin
deposition, and release of cytokines. Addition of synthetic
glucocorticoids like dexamethasone decreases this inflammatory
response and may eventually decrease the restenotic process. Since
the pharmacological mechanisms of action of antiproliferative
agents and synthetic glucocorticoids are different, agents with
different "antirestenotic mechanisms" may be expected to act
synergistically. Thus, it may be useful to combine two or more of
these agents. In light of the present disclosure, numerous other
anti-proliferative or anti-stenosis drugs and other suitable
therapeutics and adjuvants will likely occur to one skilled in the
art.
D. EXAMPLE COMPOSITIONS USEFUL FOR PRACTICING THE INVENTION
[0090] Each of the above therapeutic agents can be mixed with the
matrix material either alone or in combination. Depending on the
therapeutic agent, the agent can be combined with the matrix using
physical, chemical, or biological methods. A combination of
techniques can be used. One skilled in the art will appreciate that
the concentration of the therapeutic agent need not be and often
will not be uniform throughout the entire matrix, and the device
can comprise one or more layers, which release the therapeutic
agents at different rates. In a multilayerd device for example, the
topmost layer, the surface that will abut the vascular wall can be
composed of plain matrix without any drug. The layer immediately
below can have "drug A" with anti-proliferative and/or
anti-inflammatory and/or antibiotic properties. The next matrix
layer can either have no drug, the drug the same, a similar drug or
a different drug than drug A and so on. The matrix material in each
of these layers may be same or different. Even within the same
matrix, by altering properties like the pore size, the drug
delivery kinetics can be varied. The concentration of the drug need
not be uniform throughout the matrix
[0091] All of the foregoing therapeutic agents, biocompatible
matrix (or sealant) materials, and optional adjuvants may comprise
any number of the therapeutic agents stated herein or advantageous
for the condition or disease to be treated. Matrix material can be
defined by weight or physical dimension (e.g., 3.times.2 cm
rectangle or circle having a diameter of about 1 cm square or it
can be specified using weight e.g., in milligrams of the matrix).
The dose of therapeutic agents may be defined in different ways for
example by absolute weight in pico, nano, micro, milli or gram
quantities, where appropriate in units or international units, in
relation to the weight of the matrix e.g., microgram per milligram
of the matrix, in relation to the physical dimension of the matrix
e.g., micrograms per square mm or square cm of the matrix.
[0092] In addition, drug formulations and carrier materials useful
in the present invention are discussed in Remington: The Science
and Practice of Pharmacy (19th Ed.), Mack Publishing Co.,
Pennsylvania (1995), in Hoover, J. E., Remington's Pharmaceutical
Sciences, Mack Publishing Co., Pennsylvania (1975), in
Pharmaceutical Dosage Forms (Liberman, H. A. and Lachman, L.,
Eds.), Marcel Decker, New York (1980), and in Pharmaceutical Dosage
Forms and Drug Delivery Systems (7th Ed.), Lippincott, Williams
& Wilkins (1999).
[0093] The composition of the present invention may be in the form
of a package containing one or more of the compositions. The
composition may be packaged per application, use, device, or
procedure. The package may also contain a set of instructions. The
composition may be useful for the treatment of mammals, reptiles,
rodents, birds, farm animals, and the like, including humans,
monkeys, lemurs, horses, pigs, dogs, cats, rats, mice, squirrels,
rabbits, and guinea pigs.
E. DRUG ELUTION
[0094] The process of elution of therapeutic agent from the matrix
or sealant material to and/or through the vessel wall is merely
illustrative of one possible drug delivery process. The terms,
"effective amount" and "tissue response regulating amount" mean the
amount of the therapeutic or pharmacological agent effective to
elicit a therapeutic or pharmacological effect, including, but not
limited to, preventing, suppressing, or treating
vasculoproliferation, infection, inflammation, neointimal
hyperplasia, stenosis, restenosis, or fibrous tissue formation
without undue adverse side effects, either in vitro or in vivo. The
therapeutic agent should be administered and dosed in accordance
with good medical practices, taking into account the clinical
condition of the individual patient, the site and method of
administration, scheduling of administration, and other factors
known to medical practitioners. In human therapy, it is important
to provide a dosage form that delivers the required therapeutic
amount of the drug in vivo and renders the drug bioavailable in a
rapid or extended manner. The therapeutic amount can be
experimentally determined based on, for example, the rate of
elution of the agent from the matrix, the absorption rate of the
agent into the blood serum, the bioavailability of the agent, and
the amount of serum protein binding of the agent.
F. DEVICES USEFUL FOR PRACTICING THE INVENTION
[0095] In a conventional percutaneous procedure, vascular access is
obtained by inserting a needle percutaneously through the skin into
a blood vessel (e.g. artery or vein). The flexible end of a
guidewire is passed through the needle into the blood vessel. The
needle is then removed to leave only the guidewire in place. A
conventional introducer sheath and an arterial dilator are then
passed over the guidewire and into the artery. The guidewire and
dilator are removed, and the sheath is left in place.
[0096] A catheter or other intravascular instrument is then
inserted through the sheath and advanced in the lumen of the blood
vessel to the target location, such as the site of atherosclerosis.
An intravascular procedure such as angiography or angioplasty is
performed. With the procedure completed, the catheter and then the
sheath are removed. Once the sheath is removes hemostasis needs to
be achieved. The most common technique is to apply manual digital
pressure to the percutaneous puncture site-until hemostasis
occurs.
[0097] Instead, following a diagnostic or interventional
catheterization procedure, the present invention may be applied
directly to the site of vascular access or puncture, eliminating
the need for mechanical pressure. In a preferred embodiment, the
biological sealant matrix will seal the vascular access or puncture
and also release one or more therapeutic agents from the matrix
into the vessel wall and surrounding tissue to prevent or reduce
any tissue responses to the matrix material. Because the matrix is
biodegradable and applied externally to the vasculature, together
with one or more therapeutic agents, the invention will minimize,
eliminate or treat any inflammation, infection or other
undesirable, tissue reaction to the implanted matrix. This
therapeutic composition not only achieves hemostasis, but also
reduces or eliminates tissue response (e.g., inflammation or
infection) related to the implanted matrix. This helps the healing
process, and helps maintain the option of future vascular access
from the same site, and helps eliminate or reduce patient
discomfort or pain when healing from invasive vascular
procedures.
[0098] The present invention may be practiced in various device
forms, including, but not limited to, the sleeve, plug, sponge,
anchor, or sandwich forms. The device of the present invention may
comprise a single, double, or multiple layers. In a preferred
embodiment of the invention as a single layer sleeve form, the
protein matrix is a sheet or membrane of Type I bovine collagen,
and the therapeutic agent is rapamycin (sirolimus). A relatively
flat sheet of collagen is either impregnated, absorbed, adsorbed,
saturated, dispersed, or immobilized with rapamycin (sirolimus).
About 0.2 .mu.g/cm.sup.2-2 mg/cm.sup.2, preferably 120
.mu.g/cm.sup.2, of rapamycin (sirolimus) is combined with the
collagen matrix material, which in the dry form is a sheet that is
0.3-3.0 mm thick.
[0099] The rapamycin imbibed collagen sheet or sleeve may be
modified into a tube or other geometrical shapes and directly
secured to the outside of the native vessel, at the site of graft
anastamosis or over the vein, artery, or graft itself. The sleeve
may be secured at the desired site by sutures or staples. The
suture material itself may be combined with a therapeutic agent. In
this aspect, the therapeutic agent permeates through the vessel
wall and into the lumen. The rate of drug elution from the membrane
can be varied, and elution can continue until the matrix material
is completely resorbed.
[0100] In another aspect, the present invention may be a double or
multiple layer sleeve comprising an antiproliferative-imbibed,
inner matrix layer and an external support skeletal structure or
layer. In this embodiment, the inner matrix material is a sheet or
membrane of Type I collagen about 0.3-3 mm thick, and the exterior
skeletal support material structure is a sheet of PTFE about 0.3-3
mm thick. The antiproliferative drug, in this embodiment, is
rapamycin in an amount of about 0.2 .mu.g to 100 mgs/mg of matrix.
The sheet of collagen may be attached to the PTFE sheet using a
variety of techniques, e.g., physically using sutures, adhesives,
staples, or chemically by bonding.
[0101] The two sheet composite can be rolled to create either a
tubular structure or geometrical variations thereof. The composite
device or sleeve is then suitably trimmed so that it can be applied
over the desired site--artery, vein, graft anastomotic site, etc.
The free edges of the PTFE sleeve are attached to each other by
adhesive, sutures, staples, etc. This stabilizes the entire device
on the outside of the vascular structure or graft. The drug then
permeates through the vascular or prosthetic material wall, and
while in the wall, the drug inhibits smooth muscle cell
proliferation, an integral part of the healing response that
follows surgical construction of the graft.
[0102] After a period of time (the period can be varied based on
degree of cross linking--from a few days to several months) the
body breaks down and absorbs the collagen, leaving its exterior
support skeleton or structure intact. One skilled in the art will
appreciate that the body-resorbable aspect of the protein layer
chosen to imbibe the drug is an optional preferred practice of the
present invention. The PTFE, not being bioabsorbable, tends to hold
the resorbable protein layer in place for a length of time
sufficient for the drug to permeate through the vascular structure,
graft, or prosthetic material wall. The external PTFE layer serves
to keep the drug in close apposition with the outer aspect of the
vessel or graft wall and limits its diffusion to the surrounding
tissues and skin.
[0103] The external layer may have advantages in addition to those
from supporting the drug eluting inner membrane or matrix material.
For example, the external PTFE skeleton can function as an
additional reinforcement layer and prophylactically address
problems related to a weak scar, graft disruption, or aneurysm
formation. Although the desired effect of the imbibed drug is the
ability to inhibit the smooth muscle cell proliferative response,
it is this proliferative response that contributes to the formation
of a surgical scar of good quality or adequate firmness. A weak
scar at the site of surgical anastamosis can potentially lead to
graft disruption or aneurysm formation.
[0104] Also contemplated as within the present invention is an
exterior skeletal or support layer that is itself biodegradable.
Thus, a resorbable external skeletal structure combined with a
resorbable internal drug eluting collagen layer--the two layers
having the same or different rates of degradability and
resorption--would generate a healed vascular or graft structure
without any foreign material remaining after the procedure. One
skilled in the art would understand in view of this disclosure that
numerous other such materials are likely to be usable in this
invention. For example, Dacron.RTM. polyester can be a suitable
material for the external support structure.
[0105] The present invention also provides for device self-fixation
to the outer surface of the vascular wall. The device could be made
more adhesive to the vascular wall if, in the final stage, collagen
is combined with fibrin sealant, acetylated collagen, or
photoreactive groups such as fluorescein isothiocyanate or Rose
Bengal, both from Sigma-Aldrich Corp. (St. Louis, Mo.). Fibrin
sealant and acetylated collagen have been found to increase
adhesion of collagen matrix material to the outside vascular wall.
Stimulation of a device combined with a photoreactive groups, e.g.,
with ultraviolet light, will activate the photoreactive groups to
increase adhesion.
[0106] The present invention further provides for a device
comprising a thin layer of collagen which is applied to the
perivascular surface of a metallic closure device. The metallic
closure device may be in the form of a staple, clip, disc, or
miniature clamp that may be used for vascular closure.
[0107] FIGS. 1A, 1B, 2A, and 2B illustrate embodiments of the
present invention 1. FIG. 1A shows a rectangular sheet of a matrix
material 2 having disbursed or distributed therein an agent 3 of
the present invention (shown by stippling). FIG. 1B illustrates a
further embodiment of the invention shown in FIG. 1A in which a
hole 4 has been created in the drug-containing matrix material 3,
2. It will be understood by one skilled in the art that the
diameter of the hole 4 will be adjusted to accommodate the outside
diameter of any vascular or graft structure passing therethrough.
In one embodiment, the diameter of the hole 4 is 6 mm.
[0108] FIGS. 2A and 2B illustrate a further embodiment of the
present invention in which an exterior support or skeletal
structure or means 5 is employed. Support 5 is exterior to the
matrix material sheet 2 when the sheet 2 is rolled or coiled into a
cylindrical shape. Exterior skeletal means such as PTFE and Dacron
sheets are among the support materials presently contemplated. Many
other such exterior skeletal support means will occur to one
skilled in the art. As is shown, FIG. 2B illustrates an embodiment
of the invention in which a hole 4 (which may vary in diameter) is
employed.
[0109] FIGS. 3A, 3B, and 3C illustrate an embodiment of the
invention employing an interlocking design in which one edge of the
rectangular agent-eluting sheet or matrix material interlocks
adjacent the opposite edge. More specifically, FIG. 3A shows a
rectangular matrix material 2 having a therapeutic agent 3 (shown
in stippling) disposed or disbursed therein. Also shown on the
sheet illustrated in FIG. 3A is a series of v-shaped notches 6
located approximately adjacent one edge 7 of the agent-containing
matrix material. Cooperating with notches 6 on the opposite edge 8
is a series of projections 9, which are arrow-head shaped.
[0110] However, other combinations of projections 9 and slots 6
certainly are contemplated by this invention. Thus, assembly of a
sleeve embodiment of the present invention involves rolling edge 8
toward edge 7 (shown in FIG. 3B) and inserting projections 9 into
slots 6. As is shown in FIG. 3C, projections 9 have been inserted
into slots 6 from the inside of the tubular structure, such that
the points 10 of projections 9 project from the inside to the
outside of the structure. As is shown, the following edges 11 of
projections 9 cooperate with v-shaped slots 6 to lock the flat
structure into a cylindrical vascular-dimensioned sleeve 12.
[0111] Vascular sleeve 12 further defines a lumen 14. Lumen 14 is
of a vascular dimension such that the interior surface of sleeve 12
would be in contact with the exterior surface of a vascular
structure to which the sleeve 12 was attached. In this fashion, the
drug or agent-eluting, vascular-dimension sleeve is deployed over
and around the vascular structure with which this invention is to
be used.
[0112] FIGS. 4A and 4B illustrate a second interlocking embodiment
of the present invention. In this embodiment, a strip-form of the
present invention is utilized. Agent-eluting sleeve 16 comprises an
elongate drug or agent-eluting matrix material 17, alone or in
conjunction with an external support means (not shown). Created in
matrix material 17 are two locks 18 located on opposite ends
thereof Cooperating with lock 18 are windows 19 into which locks 18
are inserted, such that the sleeve 16 is deployed against and on
the exterior of the operant vascular structure. As is shown in FIG.
4B, lock 18 may be inserted into window 19 from the inside toward
the outside. In an alternative embodiment, lock 18 may be inserted
into window 19, from the outside toward the interior of the sleeve
structure. Also shown in FIG. 4A is a representative shunt opening
20 including two shunt contact wings or flaps 21.
[0113] FIG. 5 illustrates another embodiment of the present
invention in which an external wire support or framework means is
employed. External wire framework 20 surrounds a preferred
embodiment of the present invention, i.e., a PTFE and drug-coated
collagen matrix material 22 disposed around vessel 24.
[0114] FIGS. 6-13 illustrate various arterio-venous fistuale. A
drug eluting sleeve or matrix material of the present invention 26
is shown to be implanted, wrapped, or placed around-the various
fistulae 32 shown in the several figures. In each of these figures
venous structures are designated 28 and arterial structures are
designated 30. Arrows 34 illustrate the direction of blood
flow.
[0115] FIGS. 10-13 illustrate a further embodiment of this
invention in which a graft, e.g., a PTFE graft, 36 is used in
conjunction with the present invention. As is shown in FIG. 13,
graft 36 may itself include a matrix material with a drug or agent
36 (shown in stippling) of this invention.
[0116] A further application of the sleeve of the present invention
involves using the interior drug-imbibing protein layer as a drug
source or reservoir. Accordingly, the particular drug may be
replenished periodically, e.g., by puncturing the sleeve with a
needle and delivering additional drug thereto or creating a
reservoir for the drug within the sleeve from which it can be
gradually eluted.
[0117] Referring now to FIG. 21, in another embodiment of the
present invention as a plug, a therapeutic agent may be combined
with a matrix or sealant material to form a hemostatic plug
composition. In a preferred embodiment, a hemostatic plug
composition of collagen and rapamycin may be applied to a site of
vascular compromise to seal the puncture or opening and to prevent
or minimize the tissue response to the implanted matrix, e.g.,
inflammation and fibrosis. The composition of this embodiment may
contain rapamycin in an amount of about 0.2 .mu.g mg to about 100
mg mg per milligram weight of the hemostatic plug composition. The
hemostatic plug of the present invention may comprise a combination
of one or more types, e.g., chitosan, collagen, fibrin, and forms,
e.g., fibers, sponge, paste, gel, sheet, of hemostatic material, as
well as other therapeutic agents, e.g., anti-inflammatories,
antibiotics.
[0118] FIG. 21 illustrates an embodiment of the hemostatic plug in
a device. The plug device 100 generally comprises a plug of
hemostatic and therapeutic material 102, a plunger or applicator
104, and a sheath 106. The sheath 106 generally comprises a tubular
body defining a lumen 114, and a flange 108 disposed at the
proximal end of the sheath 106. The flange 108 is designed to serve
as a grip for the index and middle fingers (not shown). The sheath
106 may be composed of a pliable biocompatible material suitable
for use in surgical procedures and is preferably composed of a
durable plastic material.
[0119] The outer diameter of the sheath 106 and the inner diameter
of the lumen 114 are designed to permit sliding movement, with a
close fit, of the plunger or applicator 104 disposed within the
sheath 106. In the preferred embodiment, the outer diameter of the
sheath 106 is in the range of about 3 to about 10 mm. However, this
diameter may vary according to the procedural needs, as will be
readily appreciated by those skilled in the art.
[0120] The plunger or applicator 104 generally comprises a
cylindrical body and a thumb plate 110 disposed at its proximal
end. The plunger or applicator 104 will generally be composed of a
pliable biocompatible material suitable for use in surgical
procedures and is preferably composed of a durable plastic
material. The size of the outer diameter of the plunger or
applicator 104 is selected to be slightly less than the size of the
inner diameter of the lumen 114 to permit sliding passage. In the
preferred embodiment, the plunger or applicator 104 has a blunt
distal end for engaging and advancing the hemostatic plug 102
through the sheath 106 and out the outlet 112.
[0121] To use the plug device, the medical personnel positions the
distal end of the sheath 106 at the vascular puncture site and
applies pressure to the thumb plate 110 of the plunger or
applicator 104. As the plunger or applicator 104 slides through the
sheath 106, it advances the hemostatic plug 102 until it exits from
the sheath 106 through the outlet 112. The length of the sheath 106
and the plunger or applicator 104 may be selected so that when the
thumb plate 110 of the plunger or applicator 104 abuts the flange
108 of the sheath 106, the medical personnel knows that the plug
102 has been pushed entirely out of the lumen 114. The hemostatic
plug 102 may be mechanically held against the site of puncture or
opening to achieve immediate hemostasis. The hemostatic material
will begin to interact with bleeding tissue to maintain hemostasis
without mechanical pressure. An example of a device that can be
used with the present invention is disclosed in U.S. Pat. No.
5,310,407 (Casale).
[0122] An alternative embodiment of the plug of the present
invention is shown in FIG. 22. In the alternative plug device 200,
the plug of hemostatic and therapeutic material 202 may be
connected to a sealing member 204 that is located distally within
the sheath 106 and adjacent to the sheath outlet 112. The sealing
member 204 comprises a highly absorbent and compressed material,
such that it swells when deployed and comes into contact with
fluids such as blood, and is also preferably composed of a
biodegradable material. The sealing member 204 may also comprise
hemostatic and therapeutic materials, such as collagen and
rapamycin.
[0123] Attached to the sealing member 204 is a filament 206 that
extends through the plug 202 and the plunger or applicator 104 and
exits the plug device. The filament 206 is preferably composed of a
flexible, biodegradable material. To seal a vascular puncture or
opening, the plug is introduced into the artery or puncture until
the plug device 200 reaches the target location within the artery.
The plunger or applicator 104 disposed within the plug device 200
is operated to expel the plug 202 and sealing member 204. The plug
device 200 and plunger or applicator 104 may then be removed to
leave the filament 206 still attached to the plug 202 and sealing
member 204.
[0124] The medical personnel may then pull on the filament 206, to
pull the sealing member 204 toward the puncture or opening (not
shown) until the sealing member 204 engages the puncture or
opening. The sealing member 204 effectively seals the puncture or
opening in the vasculature, and the plug 202 extends through and
seals the length of the puncture or opening in the tissue adjacent
to the vasculature. The filament 206 may be secured outside the
body by a tape (not shown) or other securing means. An example of a
device that can be used with the present invention is disclosed in
U.S. Pat. No. 4,890,612 (Kensey).
[0125] The collagen matrix component of devices used to seal
vascular punctures, i.e., to obtain hemostasis, can provoke tissue
responses such as immunologically mediated allergic reactions,
fibrosis, infection, inflammation thrombosis and granulomas. Some
or all of these tissue responses can render future access of the
blood vessel difficult or impossible. Therefore, the hemostatic
plug of sealant matrix and therapeutic agent as in the present
invention may be advantageously used to seal vascular punctures and
to simultaneously reduce the tissue response to the collagen
matrix.
[0126] The matrix in a hemostatic plug of the invention may contain
collagen, fibrin, chitosan, or other similarly functioning
components useful as a biological sealant. A variety of therapeutic
agents may be combined, alone or together, with the collagen
matrix, such as antibiotics, anti-inflammatories,
antiproliferatives, hormones, or steroids, as described above. In
addition, the matrix and therapeutic agent composition may further
include adjuvants or excipients, such as agents that inhibit
accumulation of the matrix material in the vasculature or reduce
calcification of the vasculature.
[0127] Referring now to FIG. 23, in another embodiment, the present
invention provides an anchor device 300 to seal vascular punctures
and to simultaneously reduce the tissue response to the foreign
material used to seal the puncture. In lieu of a plug, an anchor
302 is attached to the plunger or applicator 104 by a filament 306
and disposed within the lumen 114 of the sheath 106 at the distal
end. The anchor 302 is preferably composed of a resilient,
biodegradable material, e.g., gelatin, and optionally composed of
or coated with hemostatic material or a therapeutic agent or both.
The filament 306 is preferably composed of a flexible,
biodegradable material. The proximal end of the filament 306 is
located external to the anchor device 300 and accessible to medical
personnel operating the anchor device 300.
[0128] When disposed within the sheath lumen 114, the anchor 302 is
in a constrained or compressed configuration, and when
unconstrained or expanded outside the sheath 106, the anchor 302
assumes an enlarged configuration, e.g., in the shape of a disc, as
shown in FIG. 24. The anchor 302 should be relatively thin so as
not to obstruct bloodflow within the vessel being treated. The
distal surface 304 of the anchor 302 expands into a relatively flat
surface, as does the proximal surface 308, which can engage the
interior of an artery or vein (not shown) to seal off the puncture
site.
[0129] To seal a puncture site, the filament 306 that is connected
to the anchor 302 may be pulled so as to pull the anchor 302 toward
the puncture site until its proximal surface 308 contacts the inner
surface of a vessel. This establishes a hemostatic seal of the
puncture, and in a preferred embodiment, the therapeutic agent
imbibed matrix material will elute the agent to also prevent,
suppress, or treat smooth muscle proliferation. The filament 306
may be secured outside the body by a tape (not shown) or other
securing means for a time sufficient to confirm hemostasis. An
example of a device that can be used with the present invention is
disclosed in U.S. Pat. No. 4,852,568 (Kensey).
[0130] Referring now to FIG. 25, in another embodiment of the
present invention as a sandwich device 400, the anchor 402 and
sealing member 404 are disposed within the sheath lumen 114 and
connected to each other and to the plunger or applicator 104 by a
filament 406. To effect a seal using the device 400, the medical
personnel inserts the sheath 106 through the vascular puncture or
incision 416 and expels the anchor 402 through the outlet 112 and
into the vascular lumen 418 by operating the plunger or applicator
104. The medical personnel then manipulates the filament 406 to
pull the anchor 402 toward the puncture site 416 until it engages
with the inner surface of the vascular wall 412 as in FIG. 26.
Again manipulating the filament 406, the medical personnel pulls
the sealing member 404 into engagement with the outer surface of
the vascular wall 414, as shown in FIG. 26. The anchor 402 and
sealing member 404 thus engage the vascular tissue around the
puncture 416 in a sandwich configuration, as shown in FIG. 26, and
seal the site.
[0131] In FIG. 25, the anchor 402 is depicted as a disc disposed
vertically so that its two flat surfaces 408, 410 are parallel to
the sheath 106 and located adjacent to the outlet 112. The sealing
member 404 sits proximal and adjacent to the anchor 402 within the
sheath lumen 114. The sealing member 404 may be tubular or
cylindrical. The filament 406 loops through the anchor 402 and
sealing member 404 and continues through the plunger or applicator
104 to the outside of the body and is accessible to medical
personnel. The plunger or applicator 104 of this device may
optionally incorporate means to visually or audibly indicate the
proper operation of the device. U.S. Pat. No. 5,021,059 (Kensey et
al.) discloses an example device as well as visual and audible
indicator means that can be used with the present invention.
[0132] The anchor 402 may be composed of a resilient, biodegradable
material such as gelatin, and preferably also composed of or coated
with hemostatic materials, therapeutic materials, or both. The
anchor 402 should be sufficiently thin or flat so as not to
obstruct bloodflow when deployed within the interior of a vessel.
In a preferred embodiment, the anchor 402 approximates the
thickness of a vessel wall and comprises collagen and rapamycin (or
other therapeutic agent(s)).
[0133] The sealing member 404 may be composed similarly but is
preferably larger and more bulky than the anchor 402 so as to exert
an expelling force on the anchor 402 during operation of the
device. The cylindrical body of the sealing member 404 may resemble
the plug shown in FIGS. 21 and 22 and may be composed of similar
hemostatic materials, e.g., chitosan, collagen, fibrin, and
therapeutic agents, e.g., antiproliferatives, antibiotics,
anti-inflammatories. Importantly, both the sealing member 404 and
anchor 402 should be resilient or firm enough to hold the filament
406 in place as shown in FIGS. 25 and 26. The filament 406 is
preferably composed of a flexible, biodegradable material.
[0134] All of the foregoing devices may comprise any or the
aforementioned therapeutic agents, and may comprise multiple layers
with varying drug densities or doses. For example, an outer layer
in immediate contact with the vascular tissue may comprise a drug
with kinetics designed for rapid release, and an inner layer not in
contact with the vascular tissue may comprise a drug with kinetics
designed for slower or extended release of the therapeutic agent.
Alternatively, all of the foregoing devices may comprise
synergistic layers. For example, the outer layer may comprise one
type of drug, e.g., an antiproliferative agent, while the inner
layer may comprise another type of therapeutic agent, e.g., an
antibiotic agent.
[0135] To illustrate further, one therapeutic agent may be used for
immediate release of rapamycin from the collagen matrix, which has
large pores ranging from about 0.001-100 .mu.m. A second
therapeutic agent may be used for extended release of dexamethasone
from the fibrin matrix, which has small pores ranging from about
0.001-0.004 m.mu.. Thus, for example, an outer layer of a device of
the invention may comprise rapamycin imbibed in a collagen matrix,
and an inner layer may comprise dexamethasone imbibed in a fibrin
matrix. The outer layer of collagen matrix will rapidly elute
rapamycin for immediate treatment of any vasculoproliferative
responses after a procedure, and the inner layer of fibrin matrix
should more slowly elute dexamethasone and/or antibiotics to
counteract any inflammation and or infection over an extended
period of time.
G. CONDITIONS AND DISEASES TREATED USING THE INVENTION
[0136] The present invention may be applicable to vascular
diagnostic and interventional procedures including but not limited
to angiography, atherectomies, angioplasty, stent implantation,
rotablators, thrombolysis therapy, laser angioplasty,
valvuloplasty, aortic prosthesis implantation, intra-aortic balloon
pumps, pacemaker implantation, dialysis, electrophysiology, and
procedures relating to percutaneous extracorporeal circulation. The
present invention may be used in both adults and children
independent of the age of the vessel to be sealed. In addition,
multiple therapeutic agents, including antibiotics,
anti-inflammatories, hormones, or steroids, may be combined with
the sealant matrix, which itself may be composed of more than one
matrix material.
H. COMBINATION THERAPY
[0137] The methods, compositions, and devices of the present
invention may be practiced in conjunction with standard or other
therapies indicated for the condition or disease to be treated. For
example, the invention may be practiced percutaneously or
surgically, while the adjunct therapy may be administered by any
appropriate route, including, but not limited to, oral,
intravenous, intramuscular, subcutaneous, percutaneous, or mucosal.
The therapies may be combined to produce synergistic effects.
[0138] "Combination therapy" refers to the administration of
therapeutic or pharmacological agents in a sequential or
substantially simultaneous manner. "Combination therapy" also
refers to the administration of the therapeutic agents described
herein in further combination with other pharmacologically active
ingredients, or to the practice of the present invention in further
combination with other methods or devices.
I. EXAMPLES
[0139] The following examples are set forth to illustrate the
device and the method of preparing matrices for delivering
therapeutic agents. The examples are set forth for purpose of
illustration and not intended to limit the present invention.
Example 1
Inhibitory Effect of Different Antiproliferative Agents
[0140] Prefabricated collagen matrices were placed in different
antiproliferative drug solutions until complete saturation
occurred. The antiproliferative drugs were chosen to represent the
more active compounds capable of smooth muscle cell and fibroblast
inhibition without inhibiting collagenase and elastase, which
enzymatically inhibit collagen accumulation--one cause of
restenosis. The collagen matrices were saturated with these
compounds at a concentration of 25 .mu.g/ml lyophilized, washed
with 0.066 M phosphate buffer of pH 7.4 at 37.degree. C. for 24
hours and cut in the shape of a disc with density of compound of
about 5 .mu.g/cm.sup.2. After washing, sterile discs 15 mm in
diameter were placed in a 24-well culture plate, and cells were
seeded at a density of 5,000/cm.sup.2. Five days later, cell number
was counted and enzymatic activity evaluated in the aliquots of
media by chromogenic substrate hydrolysis and spectrophotometry.
Among the tested agents in this comparative in vitro test,
paclitaxel and rapamycin (sirolimus) performed similarly. These
data are presented in Table 2.
2TABLE 2 Inhibitory Effect of Different Antiproliferative Agents
SMC Fibroblast Collagenase Elastase Agent Inhibition % Inhibition %
Activity % Activity % Control 0 0 100 100 (plain matrix)
Actinomycin D 44 .+-. 11 35 .+-. 8 55 .+-. 9 84 .+-. 11 Cyclosporin
A 61 .+-. 7 53 .+-. 7 104 .+-. 5 87 .+-. 7 Methotrexate 32 .+-. 9
28 .+-. 6 23 .+-. 12 14 .+-. 3 Paclitaxel 88 .+-. 6 62 .+-. 11 98
.+-. 5 90 .+-. 4 Rapamycin 94 .+-. 5 90 .+-. 12 137 .+-. 8 142 .+-.
5 Tetracycline 11 .+-. 8 13 .+-. 5 56 .+-. 8 81 .+-. 4 (free
base)
Example 2
Capacity of Different Types of Matrices to Bind Rapamycin
[0141] In the next in vitro study, the ability of different
matrices to bind rapamycin (sirolimus) was tested. A prefabricated
collagen matrix (BioMend from Sulzer Calcitek, Inc., Carlsbad,
Calif. or BIOPATCH containing collagen-alginate from Ethicon, Inc.,
Somerville, N.J.) with rapamycin (sirolimus) was prepared as
described in Example 1 at an initial rapamycin (sirolimus)
concentration of 250 .mu.g/ml. Prefabricated chitosan (using the
technique described in Aimin et al., Clin. Orthop. (1999), 366:
239-247) and fibrin matrices (using the technique mentioned in
Example 5) were also placed in 250 .mu.g/ml of rapamycin
(sirolimus) in dimethylsulfoxide (DMSO) solution until complete
saturation occurred. After solvent evaporation, the matrices
combined with drugs were washed with 0.066 M phosphate buffer of pH
7.4 at 37.degree. C. for 24 hours.
[0142] To compare matrix capacity, fluorescent rapamycin
(sirolimus) derivate loaded onto 1.88 cm.sup.2 matrix surface of
the same thickness was used. After incubation with 0.14 M NaCl
solution, the residual rapamycin (sirolimus) was extracted with
DMSO, and yield was measured using fluorescence spectroscopy. As
expected, capacity of protein matrices was found to be higher than
the polysaccharide chitosan matrix. Usefulness of fibrin or
collagen as matrix for antiproliferative drug delivery may depend
on a particular combination or additional components or
requirements of longevity of the matrix. These data are presented
in Table 3.
3TABLE 3 Matrix Capacity for Rapamycin Matrix Rapamycin Binding
Capacity (.mu.g/cm.sup.2) Chitosan 78.7 .+-. 8.9 Collagen 124.5
.+-. 14.3 Collagen-alginate 131.1 .+-. 12.3 Fibrin 145.8 .+-.
12.7
Example 3
Delivery Systems Using Liposomes
[0143] Liposomes represent a form of drug delivery system and offer
controlled release of biologically active agents. They are used in
pharmaceutical formulations, especially for water insoluble drugs,
e.g., rapamycin. Liposomal entrapment has been shown to have
considerable effect on the pharmacokinetics and tissue distribution
of administered drugs. The formulations tested included nonionic
liposomal formulation composed of glyceryl dilaureate, cholesterol,
and polyoxylene-10-stearyl (all from Sigma-Aldrich Corp.) either at
a weight ratio of 56:12:32 (Formulation 1) or nonionic 40%
hydroalcoholic oil-in-water liposomal emulsion containing isopropyl
myristate and mineral oil (both from Sigma-Aldrich Corp.)
(Formulation 2).
[0144] Rapamycin was entrapped into each formulation at a
concentration of 250 .mu.g/ml in DMSO or isopropanol, and formed
liposomes were applied on the surface of prefabricated collagen
sheets to create maximal surface density of rapamycin. Samples were
washed with 0.066 M phosphate buffer of pH 7.4 at 37.degree. C. for
24 hours. To compare matrix capacity, liposomes loaded with
fluorescent rapamycin derivate placed onto 1.88 cm.sup.2 disc was
used. After incubation with 0.14 M NaCl solution, matrices with
remaining rapamycin were extracted with DMSO, and fluorescent yield
was measured. As data presented in Table 5 indicates, liposomal
delivery systems do not have significant advantages over saturated
collagen matrix in ability to bind rapamycin. However, the
liposomal approach may be useful for other antiproliferative
drugs.
4TABLE 4 Liposomal Delivery System Rapamycin Binding Liposome
Capacity (.mu.g/cm.sup.2) Nonionic cholesterol liposomes
(Formulation 1) 117.4 .+-. 10.9 Nonionic oil-in-water emulsion
(Formulation 2) 89.6 .+-. 7.5 Saturated collagen matrix (DMSO)
124.5 .+-. 14.3 Saturated collagen matrix (isopropanol) 105.6 .+-.
9.7
Example 4
Preparation of a Laminated Collagen Film
[0145] To prepare a textured, surface-neutralized, laminated
collagen film, an isotonic suspension of insoluble fibrillar
collagen was obtained. Three liters of chilled collagen suspension
at a concentration of 5-18%, preferably 12%, was swollen ovemight
in 0.3-0.6 M acetic acid, preferably 0.52 M, at 4.degree. C. The
swollen suspension was dispersed with 3 liters of crushed ice for
10-20 minutes, preferably 12 minutes, in a blender and thereafter
homogenized for 30 minutes in an Ultra-Turrax.RTM. (Alfa Laval AB,
Sweden). The resulting slurry was filtered through a series of
filters (Cellector.RTM. from Bellco, UK) with pore sizes decreasing
from 250-20 .mu.m, mounted in filter holder (Millipore Corp.,
Billerica, Mass.). After degasation at 0.04-0.09 mbar, preferably
0.06 mbar, the slurry was mixed with 2 liters of chilled 0.1-0.05 M
NaOH, and the final pH adjusted to 7.4.+-.0.3.
[0146] The neutralized suspension can be stored at 4-6.degree. C.
only for several hours prior to matrix formation. This neutralized
suspension serves as a foundation for preparation of a saturated or
dispersed form of a matrix containing rapamycin (sirolimus). The
neutralized slurry may be directly cast as a wet film with a
thickness of 3 mm on a flat hydrophobic surface at room
temperature. A dry film with a thickness of approximately 60-70
.mu.m is formed. Three to five milliliters of slurry cover an area
of 10 cm.sup.2. On top of such a surface, several layers may be
formed. The layers will serve as a basis for preparation of a
saturated form of an antiproliferative agent by immersing the
collagen film into solutions of rapamycin, paclitaxel, or mixtures
thereof. Simultaneous combination of neutralized slurry and
rapamycin or other agents in suspension may be used for preparation
of film with dispersed form of active ingredients.
[0147] An important factor in the preparation of the matrix
material is the porosity of the protein carrier from which the
device is to be formed, since porosity controls the kinetics of
drug release. Porosity may be regulated by drying rate,
temperature, and the characteristics of the initial collagen. The
matrix should be sufficiently porous to bind small molecules such
as rapamycin (mol wt 914.2) and durable enough to maintain the
shape of device. Samples of collagen matrix with effective pore
sizes of 0.002-0.1 .mu.m were tested. Higher capacity to bind
rapamycin (sirolimus) in saturation experiments was observed with
the matrix having pore sizes of 0.004 .mu.m.
[0148] In addition, collagen matrices with bigger pore sizes are
fragile. Since the binding capacity of the matrix for the
antiproliferative agent is critical for this application, three
different concentrations of rapamycin were used to prepare a
rapamycin-collagen matrix combination from commercially available
collagen prepared at optimal density of pores. The three different
concentrations labeled high, medium, and low were 120.+-.5
.mu.g/cm.sup.2, 60.+-.4 .mu.g/cm.sup.2, and 30.+-.3 .mu.g/cm.sup.2,
respectively. None of these matrices were fragile or had
non-uniform rapamycin (sirolimus) distribution. Different densities
permit regulation of the kinetics of drug release.
Example 5
Preparation of an Implantable Fibrin Matrix Device Combined with an
Antiproliferative Agent
[0149]
[0150] In general, to make a device based on a fibrin matrix loaded
with an antiproliferative agent, aqueous fibrinogen and thrombin
solutions are prepared as described below. Commercial fibrinogen
can be acquired from such vendors as Sigma-Aldrich Corp., American
Red Cross (Washington, D.C.), or can be prepared from plasma by
well-known techniques. Alternatively, fibrinogen prepared by
recombinant methods is suitable for use. Commercial active thrombin
can be acquired from Sigma-Aldrich Corp. or from Johnson &
Johnson (New Brunswick, N.J.) as topical USP thrombin or
Thrombogen. To make the fibrinogen and thrombin solutions used to
prepare the matrix, the necessary components are measured, weighed,
and dissolved in about 900 ml of deionized water. Tables 5 and 6
disclose preferable compositions used to prepare fibrinogen and
thrombin solutions, respectively, to prefabricate the matrix.
5TABLE 5 Fibrinogen Solution Composition Composition Range
Composition Preferred Component (g/liter) (g/liter) Caprylic Acid
10-35 18.7 Fibrinogen 50-120 76 Glycerol 20-80 40.5 Heparin 0.5-6
2.38 TRIS buffer 3-25 12.1 Triton X-100 2-8 5.4
[0151]
6TABLE 6 Thrombin Solution Composition Composition Range
Composition Preferred Component (g/liter) (g/liter) Albumin 1-100
50 CaCl.sub.2 50-250 mg/liter 123 mg/liter Factor XIII 1,000-5,000
units 2,500 units Thrombin 5,000-100,000 units 8,000 units
Troglitazone 3-24 8
[0152] The glycerol in Table 6 is used as a plasticizer. Other
plasticizers would also be suitable for the present invention. TRIS
buffer is used for pH adjustment. Suitable alternatives for TRIS
include HEPES, Tricine, and other buffers with a pKa between 6.8
and 8.3. Triton X-100 is a non-ionic detergent and stabilizer and
may be substituted by other detergents and stabilizers. Caprylic
acid may be substituted by other agents that provide protection
from denaturation, e.g., alginic acid. Fibrinogen converted to
fibrin is the most critical reagent in the matrix because it
controls the material properties of the matrix, such as
flexibility, pore size, and fiber mass density. These features
determine how easily other molecules can diffuse within the matrix
and how long the matrix may remain intact before it is
resorbed.
[0153] In Table 7, albumin is a stabilizer of thrombin. Thrombin
controls the rate of fibrin matrix formation. The presence of
Factor XIII is preferred but not necessary. Factor XIII covalently
cross-links fibrin, making the matrix more stable. Calcium ions are
needed for activation of thrombin. Troglitazone (Sankyo, Japan) is
a thiazolidinedione derivative that decreases collagen accumulation
in the vascular wall (Yao et al., Heart (2000) 84: 209).
[0154] It is preferable to completely dissolve each component
before adding the next component. If necessary, after the last
component is dissolved, the pH is adjusted to 7.0-7.4 and the
solution volume adjusted to 1 liter with water. The solutions are
then degassed. Both solutions are dispensed by pump through a
mixture chamber onto a non-stick, preferably hydrophobic, surface
to form a film approximately 2 mm thick. The film is then dried for
about 3-6 hours at a temperature in the range of about
20-60.degree. C., at a pressure of about 30 torr. Residual moisture
of the film is about 10%, preferably less than 3%, of the total wet
weight.
[0155] On this surface, dry solid rapamycin is added to create
density in the range of 100-500 .mu.g/cm.sup.2 of film. A second
layer of fibrin matrix is formed on top of this surface, such that
the drug is sandwiched between the two layers of fibrin. In one
embodiment of the present invention, one would add an
antiproliferative or antirestenotic agent like rapamycin or taxol,
an antirejection drug like rapamycin or tacrolimus, an
anti-inflammatory drug, or an antisense oligonucleotide to enhance
antirestenotic effects. These solid materials would be added to
supplement the fibrin-rapamycin sandwich complex described
above.
Example 6
Method of Cross Linking Chitosan Matrix
[0156] To increase the binding capacity of a chitosan matrix for an
antiproliferative drug, fibers may be cross-linked. Fifty
milliliters of chilled chitosan suspension at a concentration from
10-25%, preferably 12%, were gently and slowly mixed with 5-25 ml
of acrylic acid chloranhydride for 30 minutes to acetylate this
polymer. After this time period, a solution of rapamycin in DMSO at
a concentration of 250 .mu.g/ml was added, mixed vigorously, and
poured onto the chitosan matrix surface for spontaneous
cross-linking and formation of conjugated rapamycin. Because of the
microporous structure of the chitosan, this approach allows an
increase in the binding capacity of the matrix from 15-45%.
Example 7
Incorporation of Rapamycin into Collagen Matrix by Dispersion,
Immobilization, and Immobilization-Dispersion
[0157] Besides the technique of saturation, rapamycin was
incorporated into the collagen matrix by three other methods:
dispersion, immobilization, and immobilization-dispersion.
[0158] Dispersion technique: An aqueous slurry of water insoluble
collagen was prepared using non-crosslinked dry, highly purified,
lyophilized calfskin collagen obtained from Elastin Products Co.
(Owensville, Mo.). This collagen and solubilizing buffer are
chilled to a temperature of 2-8.degree. C., preferably 4.degree.
C., and vigorously mixed to prepare collagen slurry containing
10-21%, preferably 12%, of collagen protein. Such slurry includes
9% of plasticizer, glycerol, 15% of rapamycin in DMSO at a
concentration of 250 .mu.g/ml, and water. The solution had a
viscosity of 50,000 cps.
[0159] Immediately after mixing with rapamycin (sirolimus), 8%
glutaraldehyde is added to the slurry (100-350 ml/liter of slurry).
The aqueous slurry must be homogenous and degassed, and the pH
adjusted to 6.0-7.1. The solution is constantly and vigorously
mixed and dispersed by pump onto a non-stick surface to form a film
approximately 2 mm thick. All procedures are carried out at a
temperature of 4.degree. C. The film is then dried for about 3-7
hours at temperatures in the vicinity of 45.degree. C., and a
pressure of 15 torr until its residual moisture is less than about
10% of the total weight. The drug solution application and drying
steps are repeated three more times.
[0160] Immobilization technique: The same collagen preparation from
Elastin Products Co. is used. One volume of 12% collagen slurry is
chilled and coupled with rapamycin (sirolimus) by esterification of
an antiproliferative drug. Esterification is carried out with 0.9 M
N-hydroxysuccynimide (Pierce Biotechnology, Inc., Rockford, Ill.)
in the presence of 0.9 M N-dicyclohexylocarbodimide (Pierce
Biotechnology, Inc.) at 2-4.degree. C. for two days. Conjugates are
prepared by titration of active N-hydroxysuccynimide ester of
rapamycin (sirolimus) in DMSO under the surface of stirred collagen
suspension. The pH of the reaction is maintained between 7.0-8.5,
preferably 7.8.
[0161] After drying, the films with conjugated rapamycin
(sirolimus) are washed with 0.15 M NaCl containing 0.02 M sodium
bicarbonate at a pH of 7.4. HPLC reveals no free rapamycin
(sirolimus) in the matrix. Rapamycin (sirolimus) ester reacts with
amino- or hydroxyl-groups of amino acid residues forming a covalent
linkage with collagen. After such immobilization, rapamycin
(sirolimus) is released as a result of in vivo or in vitro
degradation-erosion of the matrix. Nakano et al. make reference to
collagen (SM-10500) degradation and resorption by a natural
metabolic process in Rhesus monkeys during six months (Nakano et
al., Kisoto Rinsho (Clinical Report) (1995) 29: 1675-1699).
[0162] To study the rate of rapamycin release from the matrix,
samples are washed with 0.066 M phosphate buffer of pH 7.4 at
37.degree. C. for 24 hours and cut into discs with an area of 1.88
cm.sup.2, and placed into a 24-well culture plate containing 0.14 M
NaCl, 0.05M Tris buffer, 0.5% of albumin, and 0.1 mg/ml
collagenase, at pH 7.0. Collagenase is added to increase erosion of
the collagen matrix and to facilitate release of rapamycin.
Aliquots are collected at various time intervals from the wells. A
combination of dispersed and conjugated forms is also prepared. In
all these forms, the content of rapamycin is 5.0 .mu.g/cm.sup.2.
The samples are placed in wells and 1 ml of elution media
containing serum are added. Aliquots are taken every hour.
[0163] The content of rapamycin is measured according to the
procedure of Ferron et al. (Ferron et al., J. Chromatogr. B.
Biomed. Sci. Appl. (1997) 703: 243-251). These measurements are
made using batch assay and, therefore, represent release rates at 0
ml/min flow rate. The results are tabulated in Table 7 and
graphically illustrated in FIG. 14. Concentrations of the
antiproliferative drug are in .mu.g/ml.
7TABLE 7 Rate of Release of Collagen Saturated with Tetracycline
and Rapamycin (rapamycin combined with collagen matrix using four
different methods) Drug Concentration (.mu.g/ml) Collagen Rapamycin
Collagen Combination of Saturated Collagen Dispersed Conjugated
Dispersed and Time with Saturated with throughout with Conjugated
(hours) Tetracycline Rapamycin Collagen Rapamycin Forms 1 0.06 0.01
0.01 0 0.01 2 0.40 0.05 0.03 0 0.02 3 0.96 0.09 0.06 0.01 0.07 4
0.54 0.15 0.08 0.02 0.09 5 0.15 0.19 0.12 0.05 0.17 6 0.08 0.28
0.18 0.07 0.26 7 0.02 0.57 0.19 0.11 0.31 8 0.01 0.44 0.29 0.13
0.32 9 0.01 0.24 0.41 0.19 0.34 10 -- 0.20 0.62 0.27 0.41 11 --
0.19 0.61 0.31 0.78 12 -- 0.18 0.40 0.42 0.76 13 -- 0.15 0.32 0.45
0.79 14 -- 0.02 0.16 0.32 0.45 24 -- -- 0.11 0.24 0.42 Totally 0
0.003 0.23 0.53 0.39 Dissolved Matrix
[0164] These data show that different forms of drug imbedding and
drugs with different solubility have distinct kinetics. In the case
of comparatively soluble tetracycline, after saturation of the
collagen matrix with the free base, peak release occurs in a short
period of time (about three hours), whereas for less soluble
rapamycin, this peak is delayed (about seven hours). It has been
shown in experiments in vitro that collagen saturated with soluble
antibiotics such as gentamicin, cefotaxin, tetracycline, or
clindamycin delivers these antibiotics at effective concentrations
for four days (Wachol-Drewek et al., Biomaterials (1996) 17:
1733-1738). Other laboratories have shown in vivo that collagen
saturated with gentamycin at a concentration of 3 .mu.g/g and
implanted into muscle tissue is capable of delivering antibiotic
into blood through day 28. However, concentration was less than
optimal (Mehta et al., J. Orthop. Res. (1996) 14: 749-754).
[0165] Theoretically, given the low concentration of collagenase in
perivascular space and the low flow rate of perivascular fluid
(only a few milliliters per day), a matrix material saturated with
rapamycin might produce in vivo delivery kinetics, which will
support effective local concentration of an antiproliferative drug
for a period of several weeks to prevent and combat progress of
smooth muscle cell proliferation. Inhibitory concentrations for
smooth muscle cell would be in the range of 0.001-0.005 .mu.g/ml
culture media. Such levels are met or exceeded in vitro for three
weeks. Moreover, rapamycin dispersed into collagen matrix may
exhibit an antiproliferative effect for a month or longer. Finally,
conjugated and combined forms may support treatment until complete
matrix erosion.
Example 8
Biological Activity of Rapamycin in the Rapamycin-Collagen
Matrix
[0166] The most important parameter when assessing the combination
of rapamycin and collagen is inhibition of smooth muscle cell
growth. To evaluate this parameter, smooth muscle cells at a
density of 5,000 cells/cm.sup.2 are seeded onto control tissue
culture surface and testing matrices. Data are presented in Table
8. Cell growth curves are presented in FIG. 15.
8TABLE 8 Comparison of Inhibition of Growth of Smooth Muscle Cells
Using Collagen Matrices Saturated with Actinomycin D and Rapamycin
Number of Cells Days in Collagen + Collagen + Culture Control
Actinomycin D Rapamycin 0 5000 5000 5000 1 6430 .+-. 20.4 5230 .+-.
16.8 4800 .+-. 9.5 2 10240 .+-. 27.1 7350 .+-. 19.5 5040 .+-. 11.2
3 16340 .+-. 30.12 9400 .+-. 13.2 6230 .+-. 13.4 4 27100 .+-. 25.4
14280 .+-. 17.6 7400 .+-. 15.1 5 38450 .+-. 22.6 23540 .+-. 17.8
8000 .+-. 17.8 6 40000 .+-. 20.7 29300 .+-. 19.4 8550 .+-. 13.9 7
40100 .+-. 20.5 32090 .+-. 32.1 8500 .+-. 14.4
[0167] Actinomycin D is quickly released from the drug matrix and
suppresses cell growth for only a short period of time. A change of
media removes soluble actinomycin, and after several washes, no
antibiotic is present in the media or in the matrix. As a result,
cells start proliferating as usual. Rapamycin is slowly released.
Because of this slow, gradual release of rapamycin (sirolimus),
suppression of cell growth continued throughout the observation
period.
Example 9
Effect of Ratio of Matrix to Media on Antiproliferative
Activity
[0168] Two different types of matrices, collagen and fibrin
combined with antiproliferative agents, alone or in combination,
along with vitamin K, are added to the cell culture medium in
different ratios. Cells are seeded at the same density, and on day
5, numbers of viable cells are measured by Alamar blue assay. Data
are presented in Table 9.
9TABLE 9 Inhibition of Cell Growth (%) Fibrin + Matrix to Collagen
+ Collagen + Fibrin + Rapa- Media Collagen + Rapamycin + Rapamycin
+ Rapa- mycin + Ratio Rapamycin Taxol Vitamin K mycin Taxol 1:400 5
4 8 3 2 1:200 25 27 34 21 19 1:100 54 50 77 56 55 1:50 73 76 99 79
78 1:25 88 88 99 79 84 1:12.5 95 99 99 98 96 1:6.25 95 99 99 100
98
Example 10
Antiproliferative Effect of Combination of Rapamycin and Heparin
Combined to A Collagen Matrix
[0169] Antiproliferative effects of different components combined
within a matrix may exhibit a synergy. A combination of dispersed
rapamycin and soluble and immobilized heparin are used. To
immobilize heparin, 5 ml of chilled heparin solution at a
concentration of 1-10 mg/ml, preferably 5 mg/ml, is mixed with 5-20
ml, preferably 11.4 ml, of acrylic acid chloranhydride at the rate
of approximately 1 .mu.l/min, preferably 2.5 .mu.l/min. After
addition, the mixture is agitated for 30 minutes at a temperature
of 4-8.degree. C. The heparinized collagen is extensively washed
with sodium phosphate buffered saline at pH 7.4. A colorimetric
assay with Eosin A is used to determine the concentration of
heparin immobilized on matrix. Using this method, between 0.01-0.1
mg/cm.sup.2 may be covalently linked to the matrix.
[0170] Such a formulation combined with rapamycin has inhibitory
effect on smooth muscle cell growth in culture if added in the form
of suspension into the media at a ratio of 1: 100, whereas
individual forms have lesser effects--ratio of 1:25 for heparin
alone to 1:65 for dispersed rapamycin. Each of these drugs can
inhibit restenosis by different mechanisms. Hence, it is reasonable
to expect synergistic effect when using the drugs in combination.
Heparin can also be used in matrix saturated form in combination
with antiproliferatives.
Example 11
Rate of Release of Dexamethasone in Collagen Matrix
[0171] Sustained local delivery of dexamethasone in combination
with rapamycin (sirolimus) or other antiproliferative agents can be
used to simultaneously inhibit restenosis as well as inflammatory
reactions. Twenty percent (w/w) collagen slurry is prepared, to
which a 2% (w/w) suspension of dexamethasone is added. This mixture
is sprayed on to a plastic surface to form the film. The final
thickness of the film ranged from 1.92-2.14 mm (mean 2 mm). This
sheet is flexible and mechanically stable. The kinetics of
dexamethasone elution from the matrix (collagen plus rapamycin)
were characterized in an in vitro system. Fifteen-millimeter
diameter sheets were placed in the wells and immersed in 2.5 ml of
phosphate buffered solution. At time points ranging from 1-7 days,
concentrations of dexamethasone in aliquots of elution buffer were
measured by spectrophotometry. Chemical stability of the
dexamethasone through the sheet formation, drying storage, and
elution process was confirmed by HPLC. Cumulative in vitro elution
of dexamethasone is shown in Table 10.
10TABLE 10 Cumulative In-Vitro Elution of Dexamethasone from A
Collagen Matrix Time (days) Eluted Dexamethasone Mass (.mu.g) 0 0 1
211 .+-. 23 2 489 .+-. 31 3 605 .+-. 42 4 672 .+-. 38 5 725 .+-. 21
6 733 .+-. 18 7 745 .+-. 13
[0172] More than 50% of the dexamethasone elution occurred within
the first three days, with a leveling off of the elution curves
after six days. Dexamethasone can prevent a severe inflammatory
response, which is maximal during this time period, and can act
synergistically with rapamycin (sirolimus) to reduce restenosis. In
contrast to a dexamethasone eluting stent, perivascular delivery
does not inhibit endothelial cell regeneration and acts directly on
fibroblasts and smooth muscle cells.
Example 12
Rate of Release of Heparin in Collagen Matrix
[0173] Combining macro- and micro-porosity may increase capacity of
the device. Collagen and fibrin matrices were mixed to obtain such
a combination. In addition, good mechanical characteristics of
collagen improved stability of fibrin. To prepare fibrin-rapamycin
loaded matrix (rapamycin density of 150 .mu.g/cm.sup.2),
compositions disclosed in Tables 6 and 7 were used. After formation
of a first dry layer of fibrin, a second layer of collagen,
rapamycin (sirolimus), and heparin was formed as described in
Example 4 (rapamycin density of 128 .mu.g/cm.sup.2, heparin density
of 5,000 U/cm.sup.2).
[0174] The collagen fibrin sheaths loaded with medicine (thickness
2 mm) were formed as tubular structures and externally crosslinked
using high a concentration of glutaraldehyde (25%) for one minute.
After drying, the spiral form of the sleeve shown in FIG. 4 was
prepared. This sleeve was made planar on ten occasions, and the
spiral shape was restored each time. The rapamycin (sirolimus)
capacity of the final sleeve was 143 .mu.g/cm.sup.2. In vitro
elution of heparin continues for seven days. Heparin concentration
was measured as in Example 10. Buffer for the dilution was
replenished each day. The data are shown in Table 11.
11TABLE 11 Elution Profile of Heparin from A Collagen Matrix
Combined with Rapamycin and Heparin Time (days) Eluted Heparin Mass
(u/ml) 0 0 1 341 2 275 3 188 4 103 5 57 6 24 7 8
[0175] Heparin effectively inhibits smooth muscle cell
proliferation at a concentration of about 100 u/ml. In this
example, heparin can significantly inhibit smooth muscle cell
proliferation for at least four days. In addition, diffusion of
heparin from the sleeve can prevent thrombotic events on the inner
surface of the shunt and damaged vessel wall for longer periods of
time. Furthermore, the concentration of soluble heparin can be
increased up to 20,000 U/cm.sup.2 without changing the mechanical
characteristics of the matrix. Therefore, anti-smooth muscle cell
proliferation as well as antithrombotic effect can be
prolonged.
Examples 13 and 14
Comparison of In Vitro Effect of Paclitaxel, Rapamycin, and
Tacrolimus on Human Smooth Muscle and Endothelial Cells
[0176] Human smooth muscle cells and endothelial cells (Cambrex
Corp., formerly Clonetics Corp., East Rutherford, N.J.) were seeded
(100,000 cells) in 24-well plates overnight. Both cell types were
grown and maintained in Opti-MEM (Invitrogen, Carlsbad, Calif.) and
5% fetal bovine serum at 37.degree. C. in a 5% carbon dioxide and
95% atmospheric air. Cells were exposed to a range of
concentrations of rapamycin (10-100 nM), paclitaxel (0.1-10 mM),
and tacrolimus (10-100 nM). Each cell type was allowed to grow for
24 hours, last four hours in the presence of [.sup.3H
]-thymidine.
[0177] Proliferation of cells was quantified as new DNA synthesis
using [.sup.3H]-thymidine uptake assay. After 72 hours of culture,
cells were washed twice with cold phosphate buffered saline (PBS),
and 1 ml of methanol was added to the contents of each well. The
plates were kept at 4.degree. C. for 60 minutes, the cells then
washed once with cold PBS, and 500 .mu.l of 0.2 m M NaOH was added
to each well, and the plates kept at 4.degree. C. for 30 minutes.
The contents of each well were transferred into scintillation
vials, and liquid scintillation fluid was added to quantify
radioactivity using a liquid scintillation counter and the results
expressed as counts per minute. Results are shown in Tables 12 and
13 and corresponding FIGS. 16 and 17, respectively.
12TABLE 12 Comparison of Effect of Paclitaxel (3 doses), Rapamycin,
and Tacrolimus on Human Smooth Muscle Cells [.sup.3H]-Thymidine
Uptake Assay, Mean .+-. SD p Control 17434 .+-. 1822 (untreated)
Paclitaxel 2421 .+-. 206 <0.001 Paclitaxel 2527 .+-. 195
<0.001 Paclitaxel 2710 .+-. 162 <0.001 Rapamycin 6498 .+-.
245 <0.01 Tacrolimus 11995 .+-. 1850 <0.05
[0178]
13TABLE 13 Comparison of Effect of Paclitaxel (3 doses), Rapamycin,
and Tacrolimus on Human Endothelial Cells [.sup.3H]-Thymidine
Uptake Assay, Mean .+-. SD p Control (untreated) 16342 .+-. 3039
Paclitaxel 2222 .+-. 228 <0.001 Paclitaxel 2648 .+-. 248
<0.001 Paclitaxel 3459 .+-. 272 <0.001 Rapamycin 5787 .+-.
1323 <0.01 Tacrolimus 16073 .+-. 3008 ns
[0179] Rapamycin (sirolimus) and paclitaxel inhibit proliferation
(new DNA synthesis) of both human smooth muscle and endothelial
cells. Tacrolimus appears to preferentially inhibit new DNA
synthesis in human smooth muscle cells, sparing endothelial cells.
This differential effect may be extremely important and can be
beneficially exploited if tacrolimus were to be used for inhibition
of smooth muscle cell proliferation.
Example 15
Animal Studies
[0180] A proof of principle study was performed using a porcine
model. A total of six pigs were studied, two as controls and four
as treated. A 6 mm PTFE vascular graft was anastomosed between the
carotid artery on one side and the contralateral jugular vein. This
created an arterio-venous (AV) loop that is similar in construction
to the human hemodialysis access loop. A collagen sleeve combined
with a known dose of rapamycin (approximately 500 .mu.g/cm.sup.2)
was placed around the distal end of the PTFE vascular graft just
proximal to the venous anastomosis in the treated group.
[0181] After 30 days, an angiogram was performed to demonstrate
vessel and graft patency. The animals were euthanized and the
relevant segments dissected. The inhibitory effect of rapamycin
(sirolimus) on cell cycle progression is believed to be by
induction of cyclin inhibitors. Hence, expression of p21 will
increase in tissues obtained from rapamycin (sirolimus) treated
animals but not from controls. In other words, the presence of p21
confirms that the observed effect is attributable to rapamycin
(sirolimus). Tissues from treated and untreated animals were
obtained, and RNA was prepared and reverse transcribed to cDNA,
which was amplified for housekeeping gene b-actin and p21 by
PCR.
[0182] Both controls had luminal narrowing caused by severe
neointimal hyperplasia at the site of venous anastomosis (FIGS. 18A
and 19A). All four treated animals had significantly higher luminal
patency of the vein and the graft, with minimal to absent
neointimal hyperplasia (FIGS. 18B and 19B). Expression of p2l mRNA
was observed in venous tissue at the perianastamotic site obtained
from rapamycin (sirolimus) treated animals (FIG. 20) but not from
controls. This demonstrates that the rapamycin (sirolimus)
contained in the sleeve matrix was responsible for the reduction of
neointimal hyperplasia by inhibiting cellular proliferation.
Example 16
[0183] A 6.0 mm PTFE graft was anastamosed between the carotid
artery and the jugular vein. A total of 19 animals were utilized
for this study. At the time of surgical construction of the A-V
graft, collagen matrix with or without the drug was implanted at
the site of venous anastamosis. Five animals served as controls
(Group A, plain collagen matrix, no drug); the remaining 14 animals
received treatment. They were divided into two equal groups (B and
C) of seven animals each. One set of treated animals received Dose
1 (Group B, total dose 500 .mu.g) of rapamycin and the other set
received Dose 2 (Group C, total dose 2000 .mu.g of rapamycin).
Salient features of the protocol are summarized in Table 20.
Animals (n=13) were euthanized after 1 month. Tissues were formalin
fixed and sent for histology.
[0184] Histological assessment of graft explants was performed by
examining the following components: (1) the venous anastamotic
site; (a) luminal and (b) adventitial surfaces, (2) the venous end
away from the anastamosis; (c) luminal and (d) adventitial surfaces
and (3) the PTFE graft; (e) luminal and (f) abluminal surfaces away
from the anastamosis (FIG. 2). The following parameters were
evaluated: intimal thickening, inflammation, thrombus, fibrosis,
hemorrhage/fibrin and calcification or any other pathological
changes observed. Histological evaluation was scored on a 0 through
4 scale, where 0=no significant change, 1=minimal, 2=mild,
3=moderate and 4=severe.
[0185] P-values obtained from semiquantitative analysis of
histological findings using ANOVA (t-test unpaired).
14TABLE 14 Acute Chronic Collagen Inflammation Inflammation
Fibrosis Degradation Group P-Value P-Value P-Value P-Value Control
vs. 0.1259 0.5833 0.0149 0.0665 Dose 1 Control vs. 0.3071 0.4445
0.0298 0.0083 Dose 2 Dose 1 vs. 0.5247 0.8317 0.6485 0.3726 Dose
2
[0186] There was no statistical difference in the degree of
inflammation between treated and controls. There was a significant
difference in the degree of fibrosis when comparing the control
group vs. treatment groups, but no significant differences when
comparing the two dosages together. Collagen degradation was
significant in Dose 2 when compared with the control group but
insignificant when compared to Dose 1.
Example 17
[0187] A total of 4 pigs will be used, 2 controls and 2 treated. A
6 mm PTFE vascular graft will be anastomosed between the carotid
artery and the jugular vein, and this creates an arterio-venous
(AV) loop that is similar in construction to the human hemodialysis
access loop. A collagen sleeve combined with a known dose of
everolimus will be placed around the distal end of the PTFE
vascular graft just proximal to the venous anastomosis in the
treated group.
[0188] After 30 days an angiogram will done to demonstrate vessel
and graft patency, the animals will be euthanized and the relevant
segments dissected. Tissue samples will be sent for histology and
histomorphometry.
[0189] Like we have demonstrated with rapamycin, we expect to see
reduction in stenosis at the site of venous anastamosis in treated
compared to controls. This will be confirmed on angiograms as well
by amount of neointimal thickness on histomorphometry.
[0190] Those skilled in the art will appreciate that numerous other
embodiments and modifications are contemplated by the present
invention. The above description of embodiments is merely
illustrative and not intended to limit the scope of the present
invention. The patents, literature, and references cited herein are
incorporated by reference in their entireties.
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