U.S. patent application number 14/154338 was filed with the patent office on 2014-05-08 for functionalized adhesive medical gel.
This patent application is currently assigned to SOFRADIM PRODUCTION. The applicant listed for this patent is SOFRADIM PRODUCTION. Invention is credited to Philippe Gravagna, Sebastien Ladet.
Application Number | 20140128497 14/154338 |
Document ID | / |
Family ID | 42470865 |
Filed Date | 2014-05-08 |
United States Patent
Application |
20140128497 |
Kind Code |
A1 |
Ladet; Sebastien ; et
al. |
May 8, 2014 |
FUNCTIONALIZED ADHESIVE MEDICAL GEL
Abstract
A bioadherent substrate includes a medical gel or medical gel
precursor having a plurality of reactive members of a specific
binding pair attached on or adapted to be attached to a surface of
the medical gel, said reactive members being capable of forming
covalent bonds with a plurality of complementary reactive members
of the specific binding pair via a reaction selected from a Huisgen
cycloaddition reaction, a Diels-Alder reaction and a thiol-ene
reaction. A method for adhering a medical gel to biological tissue
includes providing a medical gel or a medical gel precursor having
a plurality of reactive members of a specific binding pair attached
on or adapted to be attached to a surface of the medical gel and
providing tissue with a plurality of complementary reactive members
of the specific binding pair, wherein upon contact of the reactive
members on the medical gel with the complimentary reactive members
on the tissue, covalent bonds are formed between the reactive
members and the complementary reactive members, thus adhering the
medical gel to the tissue.
Inventors: |
Ladet; Sebastien; (Lyon,
FR) ; Gravagna; Philippe; (Irigny, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SOFRADIM PRODUCTION |
Trevoux |
|
FR |
|
|
Assignee: |
SOFRADIM PRODUCTION
Trevoux
FR
|
Family ID: |
42470865 |
Appl. No.: |
14/154338 |
Filed: |
January 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12708828 |
Feb 19, 2010 |
8663689 |
|
|
14154338 |
|
|
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|
61154369 |
Feb 21, 2009 |
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Current U.S.
Class: |
523/118 |
Current CPC
Class: |
A61L 24/0031 20130101;
A61L 24/046 20130101; A61K 9/06 20130101; A61L 24/046 20130101;
C08L 101/02 20130101 |
Class at
Publication: |
523/118 |
International
Class: |
A61L 24/00 20060101
A61L024/00 |
Claims
1. A bioadherent substrate comprising a medical gel or medical gel
precursor having a plurality of reactive members of a specific
binding pair adapted to be attached on a surface of the medical
gel, said reactive members being capable of forming covalent bonds
with a plurality of complementary reactive members of the specific
binding pair via a reaction selected from the group consisting of
Huisgen cycloaddition reaction, a Diels-Alder reaction and a
thiol-ene reaction.
2. The bioadherent substrate according to claim 1 wherein the
medical gel is a hydrogel.
3. The bioadherent substrate according to claim 1 wherein the
plurality of reactive members of the specific binding pair are
selected from the group consisting of alkynes and azides.
4. The bioadherent substrate according to claim 1 wherein the
plurality of reactive members of the specific binding pair form
covalent bonds via a reaction catalyzed by copper to activate an
alkyne and an azide for [3+2] cycloaddition.
5. The bioadherent substrate according to claim 1 wherein the
plurality of reactive members of the specific binding pair form
covalent bonds via a reaction involving a cyclooctyne reagent and
an azide for [3+2] cycloaddition.
6. The bioadherent substrate according to claim 1 wherein the
plurality of reactive members of the specific binding pair are
selected from the group consisting of thiols and alkenes.
7. The bioadherent substrate according to claim 1 wherein the
plurality of reactive members of the specific binding pair are
selected from the group consisting of dienes and alkenes.
8. The bioadherent substrate according to claim 1 wherein the
medical gel is made of a polymer selected from the group consisting
of polysaccharides, mucopolysaccharides, polyaminoacids, proteins,
collagen-hydroxyethyl-methacrylate (HEMA), polyphosphazines,
polyphosphoesters, polyethylene glycol, polyethylene oxide,
polyvinyl alcohol, polyvinylpyrrolidone, polyethyloxazoline,
polyethylene oxide-co-polypropyleneoxide block copolymers,
PGA-PEG-PGA block copolymers, PGA-PEG diblock copolymers,
acrylates, PEG-oligoglycolylacrylates, polyacrylonitriles (PAN),
carboxy alkyl celluloses, poly(.alpha.-hydroxy) acids,
polylactones, polycaprolactones, polyanhydrides, polyorthoesters,
polydioxanone, styrene, acrolein and copolymers, block copolymers,
homoploymers, blends and combinations thereof.
9. A bioadherent substrate capable of covalently binding to tissue,
the bioadherent substrate comprising: a hydrogel comprising a
plurality of reactive members of a specific binding pair, the
plurality of reactive members being present on a surface of the
medical gel and capable of forming covalent bonds with a plurality
of complementary reactive members of the specific binding pair
linked to tissue via a ligand-receptor linkage, the hydrogel
capable of forming covalent bonds via a reaction selected from the
group consisting of Huisgen cycloaddition reaction, a Diels-Alder
reaction and a thiol-ene reaction.
10. The bioadherent substrate according to claim 9 wherein the
plurality of reactive members are attached directly to a polymeric
backbone of the hydrogel.
11. The bioadherent substrate according to claim 9 wherein the
hydrogel comprises a polymer selected from the group consisting of
polysaccharides, mucopolysaccharides, polyaminoacids, proteins,
collagen-hydroxyethyl-methacrylate (HEMA), polyphosphazines,
polyphosphoesters, polyethylene glycol, polyethylene oxide,
polyvinyl alcohol, polyvinylpyrrolidone, polyethyloxazoline,
polyethylene oxide-co-polypropyleneoxide block copolymers,
PGA-PEG-PGA block copolymers, PGA-PEG diblock copolymers,
acrylates, PEG-oligoglycolylacrylates, polyacrylonitriles (PAN),
carboxy alkyl celluloses, poly(.alpha.-hydroxy) acids,
polylactones, polycaprolactones, polyanhydrides, polyorthoesters,
polydioxanone, styrene, acrolein and copolymers, block copolymers,
homoploymers, blends and combinations thereof.
12. The bioadherent substrate according to claim 9 wherein the
hydrogel comprises a chemically cross linked polymer.
13. The bioadherent substrate according to claim 9 wherein the
hydrogel is an uncured liquid.
14. The bioadherent substrate according to claim 9 wherein the
hydrogel is configured to be draped over tissue having a plurality
of complementary reactive members of the specific binding pair
thereon.
15. The bioadherent substrate according to claim 9 wherein the
hydrogel is injectable.
16. The bioadherent substrate according to claim 9 wherein the
hydrogel comprises a layer configured to prevent formation of
adhesions at a surgical site, the layer having a tissue contacting
surface on which the plurality of reactive members are present.
17. A kit comprising a functionalized medical gel or medical gel
precursor having a plurality of reactive members of a specific
binding pair adapted to be presented on a surface of the gel; a
container containing a mixture which may be a solution or
suspension containing complementary reactive members of the
specific binding pair, the complementary reactive members having a
functionality that will adhere them to biological tissue upon
contact; and at least one applicator adapted to deliver the
functionalized medical gel or medical gel precursor or the mixture
to biological tissue.
Description
RELATED APPLICATIONS
[0001] This application is a Divisional application of U.S.
application Ser. No. 12/708,828 filed Feb. 19, 2010 which claims
the benefit of U.S. Provisional Patent Application No. 61/154,369
filed Feb. 21, 2009, the entire contents of which are incorporated
herein by reference.
BACKGROUND
[0002] 1. Technical Field
[0003] The present disclosure relates to adhesive modalities for
repair of biological tissues.
[0004] 2. Related Art
[0005] Medical adhesives or "tissue glue" have much potential in
medicine. Certain adhesive materials are known which may be used to
adhere tissue such as skin. For example, cyanoacrylate adhesives
been used to bond tissue. In addition to cyanoacrylate adhesives,
other types of materials have been reported to adhere to skin. For
example, U.S. Pat. No. 4,839,345 to Doi et al. reports a hydrated
crosslinked protein adhesive gel that is used as a cataplasm or
cosmetic mask that will externally adhere to skin but can be
removed and then re-adhered to the skin. Other crosslinked protein
hydrogels have been reported to serve as a proteinaceous substrate
to deliver therapeutic agents such as enzymes or drugs through skin
or mucous membranes. Still other materials have been used as
hemostatic agents to stop or prevent bleeding. For example,
mixtures of fibrinogen and thrombin such as TISSEEL.RTM. sealant
available from Baxter International, Inc. or BERIPLAST-P.RTM.
hemostatic agent or sealant available from Aventis Behring, have
been used in vascular surgery to seal tissue such as blood vessels
and thus prevent blood leakage. However, surgical adhesives can
tend to form a physical barrier between the item or items being
attached to biological tissue, thus interfering with tissue
ingrowth into the item when ingrowth is desired.
[0006] The use of medical gels such as hydrogels can be
advantageous due to the physico-chemical properties of the
hydrogels. Hydrogels typically have excellent compatibility with
human and animal tissue. Physically cross linked hydrogels can
withstand attack by body fluids, blood, urine and other bodily
secretions without significant damage. Many are typically
non-adherent to tissue, do not have an affinity for binding to
proteins and do not have cell adsorption. Hydrogels are typically
non-thrombogenic. These characteristics have been utilized, e.g.,
for prevention of adhesions after surgery. The ability of hydrogels
to act as bulking agents has been utilized in connection with
treatment of gastroesophageal reflux disease (GERD), urinary
incontinence, fecal incontinence and sterilization of mammals.
Hydrogels have also been used to create a matrix in the treatment
of damaged cartilage.
[0007] Click chemistry is a popular term for reliable reactions
that make it possible for certain chemical building blocks to
"click" together and form an irreversible linkage. See, e.g., US
Pub. No. 2005/0222427. In the case of azide-alkyne click chemistry,
the reactions may be catalyzed or uncatalyzed. For example,
copper-free click chemistry was recently developed by Bertozzi and
colleagues using difluorinated cyclooctyne or DIFO, that reacts
with azides rapidly at physiological temperatures without the need
for a toxic catalyst. See, e.g., Baskin et al., Copper Free Click
Chemistry for Dynamic In Vivo Imaging, PNAS, vol. 104, no. 43,
16793-16797 (Oct. 23, 2007). The critical reagent, a substituted
cyclooctyne, possesses ring strain and electron-withdrawing
fluorine substituents that together promote a [3+2] dipolar
cycloaddition with azides. See also, US Pub. No. 2006/0110782 and
Codelli et al., Second Generation Difluorinated Cyclooctynes for
Copper-Free Click Chemistry, J. Am. Chem. Soc., vol. 130, no. 34,
11486-11493 (2008). Another suitable cyclooctyne is
6,7-dimethoxyazacyclooct-4-yne (DIMAC). See, Sletton and Bertozzi,
A hydrophilic azacyclooctyne for Cu-free click chemistry, Org.
Lett. (2008) 10 (14), 3097-3099. Other click chemistry reactions
include Diels-Alder reactions, thiol-alkene reactions, and
maleimide-thiol reactions.
[0008] It would be advantageous to be able to secure medical gels
via selective attachment at target sites within the body to prevent
migration of the hydrogel without interfering with other hydrogel
properties such as durability and the ability to be generally
non-adherent when or where desired.
SUMMARY
[0009] A method for adhering a medical gel to biological tissue is
provided which includes providing a medical gel having a plurality
of reactive members of a specific binding pair attached on to a
medical gel or to precursor molecules of the medical gel, and
providing tissue with a plurality of complementary reactive members
of the specific binding pair, wherein upon contact of the reactive
members of the medical gel with the complimentary reactive members
on the tissue, covalent bonds are formed between the reactive
members and the complementary reactive members, thus adhering the
medical gel to the tissue.
[0010] A bioadherent substrate is provided which includes a medical
gel having a plurality of reactive members of a specific binding
pair attached thereto, said reactive members being capable of
forming covalent bonds with a plurality of complementary reactive
members of the specific binding pair via a reaction selected from a
Huisgen cycloaddition, a Diels-Alder reaction, a thiol-alkene
reaction.
[0011] A kit is provided which includes a functionalized medical
gel or medical gel precursor molecules having a plurality of
reactive members of a specific binding pair adapted to be attached
to the gel or medical gel precursor molecules; a container
containing a solution or suspension of complementary reactive
members of the specific binding pair, the complementary reactive
members having a functionality that will adhere them to biological
tissue upon contact; and at least one applicator adapted to deliver
the functionalized medical gel or medical gel precursors or the
solution or suspension to biological tissue.
DETAILED DESCRIPTION
[0012] A surgical adhesive system for medical gels and biological
tissue is provided which covalently bonds reactive members of a
specific binding pair to one another via click chemistry. Click
chemistry refers to a collection of reactive members having a high
chemical potential energy capable of producing highly selective,
high yield reactions. The reactive members react to form extremely
reliable molecular connections in most solvents, including
physiologic fluids, and often do not interfere with other reagents
and reactions. Examples of click chemistry reactions include
Huisgen cycloaddition, Diels-Alder reactions, thiol-alkene
reactions, and maleimide-thiol reactions.
[0013] Huisgen cycloaddition is the reaction of a dipolarophile
with a 1,3-dipolar compound that leads to 5-membered
(hetero)cycles. Examples of dipolarophiles are alkenes and alkynes
and molecules that possess related heteroatom functional groups
(such as carbonyls and nitriles). 1,3-Dipolar compounds contain one
or more heteroatoms and can be described as having at least one
mesomeric structure that represents a charged dipole. They include
nitril oxides, azides, and diazoalkanes. Metal catalyzed click
chemistry is an extremely efficient variant of the Huisgen
1,3-dipolar cycloaddition reaction between alkyl-aryly-sulfonyl
azides, C--N triple bonds and C--C triple bonds which is
well-suited herein. The results of these reactions are 1,2
oxazoles, 1,2,3 triazoles or tetrazoles. For example, 1,2,3
triazoles are formed by a copper catalyzed Huisgen reaction between
alkynes and alkyl/aryl azides. Metal catalyzed Huisgen reactions
proceed at ambient temperature, are not sensitive to solvents,
i.e., nonpolar, polar, semipolar, and are highly tolerant of
functional groups. Non-metal Huisgen reactions (also referred to as
strain promoted cycloaddition) involving use of a substituted
cyclooctyne, which possesses ring strain and electron-withdrawing
substituents such as fluorine, that together promote a [3+2]
dipolar cycloaddition with azides are especially well-suited for
use herein due to low toxicity as compared to the metal catalyzed
reactions. Examples include DIFO and DIMAC. Reaction of the alkynes
and azides is very specific and essentially inert against the
chemical environment of biological tissues. One reaction scheme may
be represented as:
##STR00001##
where R is a polymeric backbone and R' is a component of a biologic
tissue. Alternatively, R is a component of a biologic tissue and R'
is a polymeric backbone.
[0014] The Diels-Alder reaction combines a diene (a molecule with
two alternating double bonds) and a dienophile (an alkene) to make
rings and bicyclic compounds. Examples include:
##STR00002##
[0015] The thiol-alkene (thiol-ene) reaction is a hydrothiolation,
i.e., addition of RS--H across a C.dbd.C bond. The thiol-ene
reaction proceeds via a free-radical chain mechanism. Initiation
occurs by radical formation upon UV excitation of a photoinitiator
or the thiol itself. Thiol-ene systems form ground state charge
transfer complexes and therefore photopolymerize even in the
absence of initiators in reasonable polymerization times. However,
the addition of UV light increases the speed at which the reaction
proceeds. The wavelength of the light can be modulated as needed,
depending upon the size and nature of the constituents attached to
the thiol or alkene. A general thiol-ene coupling reaction
mechanism is represented below:
##STR00003##
[0016] In accordance with the disclosure herein, a medical gel,
such as a hydrogel, is provided with a plurality of reactive
members of a specific binding pair attached on the surface of the
gel or to precursor molecules which form the gel. As used herein,
unless otherwise specified, "attached to the surface of the gel" or
"attached on the surface of the gel" or "located on the gel" is
intended to include attachment to molecules which are precursors of
the gel. When the reactive members of the medical gel are contacted
with biological tissue containing complementary reactive members of
the specific binding pair, covalent attachment occurs, thus
adhering the gel to the tissue. In embodiments, the reactive
members may be either a dipolarophile or a 1,3 dipolar compound
depending on which complement is applied to the target tissue or
the medical gel. For example, if a dipolarphile is located on the
gel, the 1,3 dipolar compound will be located on the tissue. If a
dipolarphile is located on the tissue, the 1,3 dipolar compound
will be located on the gel. In embodiments, the Diels-Alder members
of a specific binding pair may be either a diene and a dienophile
depending on which complement is applied to the target tissue or
the medical gel. For example, if a diene is located on the gel, the
dienophile can be located on the tissue. If a diene is located on
the tissue, the dienophile can be located on the gel. In
embodiments, the thiol-ene members of a specific binding pair may
be either a thiol and an alkene depending on which complement is
applied to the target tissue or the gel. For example, if a thiol is
located on the gel, the alkene can be located on the tissue. If a
thiol is located on the tissue, the alkene can be located on the
gel.
[0017] The medical gel may be biocompatible and absorbable or
biocompatible and non-absorbable. In one embodiment, the reactive
members are attached directly to the polymeric backbone of the gel.
In another embodiment, the reactive members are attached to the
polymeric backbone via a cross-linker. Cross-linkers are discussed
below. Hydrogels can be formed, e.g., when an organic polymer, also
referred to herein as precursor molecules which form the gel, which
can be natural or synthetic, is set or at least partially
solidified to create a three-dimensional open-lattice structure
that entraps molecules of water or other solutions to form a gel.
Hydrogels have an affinity for water and typically swell in water,
but do not necessarily dissolve in water. Solidification can occur
by aggregation, coagulation, hydrophobic interactions,
cross-linking, or similar means. In certain embodiments, hydrogels
are formed by polymerization and crosslinking of a hydrophilic
monomer in an aqueous solution to cause the solution to gel. In
embodiments, the hydrogel is composed of 85% water, to which can be
added any salt or adjuvant.
[0018] Hydrogels may be organic gels or inorganic gels. Organic
gels from which the hydrogel of the invention can be selected
include, by way of example and not by way of limitation, gels
formed from polysaccharides and mucopolysaccharides including, but
not limited to hyaluronic acid, dextran, heparin sulfate,
chondroitin sulfate, agar, starch, and alginate; proteins,
including but not limited to, fibronectin, gelatin, collagen,
fibrin, chitosan, chitin, pectins, albumin, ovalbumin, and
polyamino acids; collagen-hydroxyethyl-methacrylate (HEMA);
polyphosphazines; polyphosphoesters; polyethylene glycol;
polyethylene oxide; polyvinyl alcohol; polyvinylpyrrolidone;
polyethyloxazoline; polyethylene oxide-co-polypropyleneoxide block
copolymers; PGA-PEG-PGA block copolymers; PGA-PEG diblock
copolymers; acrylates, including but not limited to diacrylates,
oligoacrylates, methacrylates, dimethacrylates and
oligomethacrylates; PEG-oligoglycolylacrylates; polyacrylonitriles
(PAN); carboxy alkyl celluloses, including but not limited to
carboxymethyl cellulose; partially oxidized cellulose;
biodegradable polymers including but not limited to polymers and
oligomers of glycolide, lactide, polyesters of .alpha.-hydroxy
acids, including lactic acid and glycolic acid, such as the
poly(.alpha.-hydroxy) acids including polyglycolic acid,
poly-DL-lactic acid, poly-L-lactic acid, and terpolymers of
DL-lactide and glycolide; .epsilon.-caprolactone and
.epsilon.-caprolactone copolymerized with polyesters; polylactones
and polycaprolactones including poly(.epsilon.-caprolactone),
poly(.delta.-valerolactone) and poly(.gamma.-butyrolactone);
polyanhydrides; polyorthoesters; polydioxanone; and other
biologically degradable polymers that are non-toxic or are present
as metabolites in the body; as well as non-degradable polymers such
as styrene and acrolein.
[0019] Collagen-hydroxyethyl-methacrylate (EMA) hydrogel polymer is
commonly formed from a gelled and crosslinked hydrophilic monomer
solution to form a three dimensional polymeric meshwork anchoring
macromolecules. Crosslinking of the hydrophilic monomer solution
can be accomplished by free radical polymerization of hydrophilic
monomers, such as hydroxyethyl-methacrylate (HEMA). Hydrogel
polymers formed by free radical polymerization of monomer solutions
require crosslinking to form the three dimensional network to gel
the aqueous solution. HEMA monomer solutions typically can be
crosslinked to gel by dimethacrylate, although other crosslinking
agents, such as ethylene glycol dimethacrylate or
methylmethacrylate, can also be used during polymerization to
modify the hydrogel. A wide variety of other hydrophilic monomers
may also be suitable for purposes of the invention. Inorganic gels
include, by way of example and not by way of limitation, silica,
alumina, and ferric oxide.
[0020] Bulk and cellular hydrogels may be prepared by covalent
cross linking or physical cross linking of the hydrogel molecules.
Thus, covalent cross linking, also known as chemical cross linking,
includes the use of multi-functional reactive chemical molecules
such as aldehydes, maleic acid, dimethyl urea, di-isocyanates,
boric acid, and the like, and also the use of ionizing radiation,
ultraviolet light, and the like, while physical cross linking
methods, also known as reversible cross linking, includes cross
linking through crystallites, hydrogen bonding and complexing
agents such as titanium, aluminum, manganese, and copper, to name a
few. Physical cross linking through formation of crystallites in,
e.g., polyvinyl alcohols, chitosan and the like, using, for
example, partial freeze-drying, repeated freezing and thawing, low
temperature crystallization, physical cross linking induced by the
presence of aqueous solutions of organic compounds, salts, acids
and bases and the like.
[0021] In the present application, the term "bioresorbable" and
"bioabsorbable" are used interchangeably and are intended to mean
the characteristic according to which an implant and/or a material
is resorbed by the biological tissues and the surrounding fluids
and disappears in vivo after a given period of time, that may vary,
for example, from one day to several months, depending on the
chemical nature of the implant and/or of the material. Non
bioresorbable material--also called permanent material--is not
substantially resorbed by tissues and surrounding fluids, after 2
years and more, keeping in particular most (e.g., >80%) of their
mechanical properties after such a time. The term "biocompatible"
is intended to mean the characteristic according to which an
implant and/or a material is well integrated by the biological
tissues and the surrounding fluids without inducing excessive
inflammation reaction around the bulk of the material or due to its
degradation. The material should avoid also the formation of a
fibrous capsule which usually results in the delay of the cellular
integration of a porous implant.
[0022] Many of the above described examples of polymers do not
contain functional groups in their molecules. In embodiments, the
reactive members are attached to the medical gel by surface
modification techniques such as plasma treatment, silane coupling
treatment and acid sensitization. Surface activation of the medical
gel can be achieved by acid or base hydrolysis, treatment by means
of cold plasma, by chemical reactions or electromagnetic
radiations.
[0023] Hydrolysis can be conducted in the presence of an aqueous
solution of a base or an acid to accelerate surface reaction,
inasmuch as excessively long processes of activation can induce a
reduction in molecular weight and thus in the mechanical properties
of the material. Suitable bases for obtaining watery solutions
suited to the aim are, for example, strong alkalis, such as LiOH,
Ba(OH).sub.2, Mg(OH).sub.2, NaOH, KOH, Na.sub.2CO.sub.3,
Ca(OH).sub.2 and the weak bases, such as for example NH.sub.4OH and
the amines such as methylamine, ethylamine, diethylamine and
dimethylamine. Acids suitable for surface hydrolysis treatments can
be chosen, for example, from among HCl, HClO.sub.3, HClO.sub.4,
H.sub.2SO.sub.3, H.sub.2SO.sub.4, H.sub.3PO.sub.3, H.sub.3PO.sub.4,
HI, HIO.sub.3, HBr, lactic acid, glycolic acid. Surface activation
by means of hydrolysis can be conducted at temperatures preferably
comprised between 0 degrees Celsius and the material softening
temperature.
[0024] Plasma treatment can be carried out both in the presence of
a reactive gas, for example air, Ar, O.sub.2 with the formation of
surface activation of oxygenate type, such as --OH, --CHO,
--COOH.
[0025] Surface treatment, whether hydrolytic or with plasma, can
remain unaltered or can be followed by further chemical
modifications to provide the first reactive groups on the
bioabsorbable polymeric substrate. Thus, for example, the COONa
groups generated by a base hydrolysis can be subsequently converted
into COOH groups by treatment with strong mineral acids. Further,
the surface freeing of alcoholic groups by means of a hydrolysis
process can be followed by reaction by means of the addition of a
compound provided with functional group or groups able to react
with surface alcoholic groups, such as for example by means of the
addition of an anhydride such as succinic anhydride, with the
conversion of --OH groups into --O--CO--CH.sub.2--CH.sub.2--COOH
groups. Suitable surface activation techniques are disclosed in
U.S. Pat. No. 6,107,453, the entire disclosure of which is
incorporated herein by this reference.
[0026] During manufacture of polymers, pendant functional groups
can be incorporated into the polymer backbone by, e.g.,
copolymerization with functionalized monomer such as lactones,
cyclic carbonates and morpholine-2,5-diones. The azido group,
N.sub.3 is a nucleophilic group that will exchange with other
nucleophilic groups, e.g., --OH, --NH.sub.2 and halogens (Br, Cl,
or I). For example, 1,3-dipolar compounds may be conjugated to
aliphatic polyesters, by copolymerizing, e.g.,
.epsilon.-caprolactone and .alpha.-chloro-.epsilon.-caprolactone
and then substituting an azide group for the Cl atom. Polyesters
can incorporate pendant dipolarophiles, e.g., propargyl groups, by
copolymerization of .epsilon.-caprolactone and
.alpha.-propargyl-.delta.-valerolactone. Copolymers of L-lactide
containing propargyl groups may, e.g., be prepared by ring opening
copolymerization of 5-methyl-5-propargyloxycarbonyl-1,3-dioxanone
with L-lactide at a molar ratio of about 90:10 with ZnEt.sub.2 as a
catalyst. See, Shi et al., Biomaterials, 29 (2008)1118-1126. Azide
functionalized polystyrene is synthesized using atom transfer
radical polymerization and subsequent modification with
azidotrimethylsilane and tetrabutylammonium fluoride. See, Dirks,
et al., Chem. Comm., (2005) 4172-4174. Azides may be incorporated
onto methacrylates, e.g., 3 azidopropyl methacrylate which is
copolymerized to a block copolymer. Diels-Alder functionalities and
thiol-ene functionalities are likewise incorporated into polymers
herein.
[0027] Biological tissue is provided with reactive members or
complementary reactive members of a specific binding pair by
conjugation to various components of tissue such as proteins,
lipids, oligosaccharides, oligonucleotides, glycans, including
glycosaminoglycans. In one embodiment, the reactive members or
complementary reactive members are attached directly to components
of the tissue. In another embodiment, the reactive members or
complementary reactive members are attached to components of the
tissue via a linker. In either case, situating the reactive members
or complementary reactive members on the tissue can be accomplished
by suspending the reactive members or complementary reactive
members in a solution or suspension and applying the solution or
suspension to the tissue such that the reactive member or
complementary reactive members binds to a target. The solution or
suspension may be poured, sprayed or painted onto the tissue,
whereupon the reactive members are incorporated into the
tissue.
[0028] 1,3-Dipolar compounds can be incorporated into proteins,
lipids, oligosaccharides, oligonucleotides and glycans using, e.g.,
metabolic machinery, covalent inhibitors and enzymatic transfers.
For example, an azido group, N.sub.3, can be applied at the
N-terminus of proteins or peptides using azidoacetyl chloride. See,
e.g., Haridas, et al., Tetrahedron Letters 48 (2007) 4719-4722. The
azido group is a nucleophilic group that will exchange with other
nucleophilic groups, e.g., --OH, --NH.sub.2 and halogens (Br, Cl,
or I). NaN.sub.3 is an azidizing agent which is capable of aziding
proteins by simply contacting the proteins with a 10 times molar
excess of NaN.sub.3. A process for C-terminal azidization is
described in Cazalis, et al., Bioconjugate Chem., 15 (2004)
1005-1009. Incubation of cells with peracetylated
N-azidoacetylmannosamine provides cell surface glycans with azido
sialic acid. See, e.g., Codelli et al., J. Amer. Chem. Soc., 130
(34) 11486-11493 (2008). Azido-tagged lipids are described in
Smith, et al., Bioconjugate Chem., 19 (9), 1855-1863 (2008).
PEGylation is a commonly used technique for adding groups to
peptides and proteins and is suitable for use herein. For example,
PEG may be covalently bound to amino acid residues via a reactive
group. Reactive groups (as opposed to reactive members herein) are
those to which an activated PEG molecule may be bound (e.g., a free
amino or carboxyl group). For example, N-terminal amino acid
residues and lysine (K) residues have a free amino group and
C-terminal amino acid residues have a free carboxyl group.
Sulfhydryl groups (e.g., as found on cysteine residues) may also be
used as a reactive group for attaching PEG. In addition,
enzyme-assisted methods for introducing activated groups (e.g.,
hydrazide, aldehyde, and aromatic-amino groups) specifically at the
C-terminus of a polypeptide. Accordingly, PEG incorporating
1,3-dipolar compounds may be utilized herein Those skilled in the
art can utilize any known process for coupling a 1,3-dipolar
compound into proteins, lipids, oligosaccharides, oligonucleotides
and glycans.
[0029] Dipolarophile functionalized proteins and peptides can be
synthesized by linking at the N-terminus with, for example, an
alkyne (e.g., 3 butynyl chloroformate), in connection with a
tripeptide (GlyGlyArg). See, Dirks, et al., supra. A suitable
tripeptide herein is the well-known cell adhesion sequence RGD. It
should be understood that, as used herein, "proteins" is intended
to encompass peptides and polypeptides. In one embodiment, thiols
on cysteines are functionalized with alkyne bearing maleimide. Id.
Providing a C-terminal dipolarophile can be accomplished, e.g., by
coupling with propargylamine using a cross-linking agent such as
N-hydroxysuccinimide/DCC. See, e.g., Haridas, et al. supra.
Terminal alkynes can be installed using metabolic building blocks
such as alkynoic acids. Lipids may be functionalized with alkynes.
For example, alkyne modified fatty acids can be generated by
reaction of terminal alkynyl-alkyl bromide with trimethyl phosphine
to yield a 16-carbon alkynyl-dimethylphosphonate. See, e.g.,
Raghavan et al., Bioorg. Med. Chem. Lett., 18 (2008) 5982-5986. As
above, PEGylation may be used for adding dipolarophile groups to
peptides and proteins and is suitable for use herein. Diels-Alder
functionalities and thiol-ene functionalities are likewise attached
to proteins, lipids, oligosaccharides, oligonucleotides and
glycans.
[0030] The reactive members or complementary reactive members may
be also attached to biological tissue or the medical gel via a
linker. In certain embodiments, the linker is or includes a ligand
which bears a reactive member. The ligand binds to a desired target
on the tissue and thus provides a vehicle for transporting and
indirectly binding the reactive member or complementary reactive
member to the tissue. The ligand herein is any molecule or
combination of molecules which demonstrates an affinity for a
target. Examples of ligands include nucleic acid probes,
antibodies, hapten conjugates, and cell adhesion peptides such as
RGD. The mechanisms involved in obtaining and using such ligands
are well-known. In embodiments, reactive members or complementary
reactive members are incorporated into saccharides or
polysaccharides and metabolically incorporated into cells. See,
e.g., Baskin et al., supra.
[0031] Antibodies that specifically recognize antigens are useful
in accordance with one embodiment herein. Antibodies which are
conjugated to a reactive member or complementary reactive members
are utilized to bind to proteins located on tissue. Monoclonal or
polyclonal antibodies are raised against an antigen which can be
any component of biological tissue and then purified using
conventional techniques. The term "antibody" is intended to include
whole antibodies, e.g., of any isotype (IgG, IgA, IgM, IgE, etc.),
and to include fragments thereof which are also specifically
reactive with a vertebrate, e.g., mammalian, protein. Antibodies
may be fragmented using conventional techniques and the fragments
screened for utility in the same manner as for whole antibodies.
Thus, the term includes segments of proteolytically-cleaved or
recombinantly-prepared portions of an antibody molecule that are
capable of selectively reacting with a certain protein.
Non-limiting examples of such proteolytic and/or recombinant
fragments include Fab, F(ab')2, Fab', Fv, and single chain
antibodies (scFv) containing a V[L] and/or V[H] domain joined by a
peptide linker. The scFv's may be covalently or non-covalently
linked to form antibodies having two or more binding sites. The
present disclosure includes polyclonal, monoclonal or other
purified preparations of antibodies and recombinant antibodies.
[0032] After purification, the ligands (e.g., antibodies, nucleic
acid probes, hapten conjugates and cell adhesion peptides), are
conjugated or linked to reactive members or complementary reactive
members in the manners described above. In addition, reactive
members or complementary reactive members can be linked to ligands
by cross-linking procedures which, in accordance with the present
invention, do not cause denaturing or misfolding of the ligands.
The terms "linked" or "conjugated" as used herein are used
interchangeably and are intended to include any or all of the
mechanisms known in the art for coupling the reactive members or
complementary reactive members to the ligand. For example, any
chemical or enzymatic linkage known to those with skill in the art
is contemplated including those which result from photoactivation
and the like. Homofunctional and heterobifunctional cross linkers
are all suitable. Reactive groups (distinguishable from reactive
members or complementary reactive members herein) which can be
cross-linked with a cross-linker include primary amines,
sulfhydryls, carbonyls, carbohydrates and carboxylic acids.
[0033] Cross-linkers are conventionally available with varying
lengths of spacer arms or bridges. Cross-linkers suitable for
reacting with primary amines include homobifunctional cross-linkers
such as imidoesters and N-hydroxysuccinimidyl (NHS) esters.
Examples of imidoester cross-linkers include dimethyladipimidate,
dimethylpimelimidate, and dimethylsuberimidate. Examples of
NHS-ester cross-linkers include disuccinimidyl glutamate,
disucciniminidyl suberate and bis(sulfosuccinimidyl) suberate.
Accessible amine groups present on the N-termini of peptides react
with NHS-esters to form amides. NHS-ester cross-linking reactions
can be conducted in phosphate, bicarbonate/carbonate, HEPES and
borate buffers. Other buffers can be used if they do not contain
primary amines. The reaction of NHS-esters with primary amines
should be conducted at a pH of between about 7 and about 9 and a
temperature between about 4.degree. C. and 30.degree. C. for about
30 minutes to about 2 hours. The concentration of NHS-ester
cross-linker can vary from about 0.1 to about 10 mM. NHS-esters are
either hydrophilic or hydrophobic. Hydrophilic NHS-esters are
reacted in aqueous solutions although DMSO may be included to
achieve greater solubility. Hydrophobic NHS-esters are dissolved in
a water miscible organic solvent and then added to the aqueous
reaction mixture.
[0034] Sulfhydryl reactive cross-linkers include maleimides, alkyl
halides, aryl halides and a-haloacyls which react with sulfhydryls
to form thiol ether bonds and pyridyl disulfides which react with
sulfhydryls to produce mixed disulfides. Sulfhydryl groups on
peptides and proteins can be generated by techniques known to those
with skill in the art, e.g., by reduction of disulfide bonds or
addition by reaction with primary amines using 2-iminothiolane.
Examples of maleimide cross-linkers include succinimidyl
4-{N-maleimido-methyl)cyclohexane-1-carboxylate and
m-maleimidobenzoyl-N-hydroxysuccinimide ester. Examples of
haloacetal cross-linkers include
N-succinimidyl(4-iodoacetal)aminobenzoate and
sulfosuccinimidyl(4-iodoacetal)aminobenzoate. Examples of pyridyl
disulfide cross-linkers include
1,4-Di-[3'-2'-pyridyldithio(propionamido)butane] and
N-succinimidyl-3-(2-pyridyldithio)-propionate.
[0035] Carboxyl groups are cross-linked to primary amines or
hydrazides by using carbodimides which result in formation of amide
or hydrazone bonds. In this manner, carboxy-termini of peptides or
proteins can be linked. Examples of carbodiimide cross-linkers
include 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide
hydrochloride and N, N.sup.1-dicyclohexylcarbodiimide. Arylazide
cross-linkers become reactive when exposed to ultraviolet radiation
and form aryl nitrene. Examples of arylazide cross-linkers include
azidobenzoyl hydrazide and N-5-azido-2 nitrobenzoyloxysuccinimide.
Glyoxal cross linkers target the guanidyl portion of arginine. An
example of a glyoxal cross-linker is p-azidophenyl glyoxal
monohydrate.
[0036] Heterobifunctional cross-linkers which possess two or more
different reactive groups are suitable for use herein. Examples
include cross-linkers which are amine-reactive at one end and
sulfhydryl-reactive at the other end such as
4-succinimidyl-oxycarbonyl-a-(2-pyridyldithio)-toluene,
N-succinimidyl-3-(2-pyridyldithio)-propionate and the maleimide
cross-linkers discussed above.
[0037] Attachment of reactive members or complementary reactive
members to the medical gel functionalizes the gel such that upon
exposure to their complementary reactive members which are situated
on tissue, they are activated and form a covalent bond, thus
adhering the gel to the tissue. In one embodiment, a linker between
the product of the reactive members or complementary reactive
members and the biological tissue is degradable by, e.g.,
hydrolysis or enzymatic action. In this manner, the medical gel can
be removable after a period of time. The degradable linkage may be
chelates or chemically or enzymatically hydrolyzable or absorbable.
Illustrative chemically hydrolyzable degradable linkages include
polymers, copolymers and oligomers of glycolide, dl-lactide,
1-lactide, caprolactone, dioxanone, and tritnethylene carbonate.
Illustrative enzymatically hydrolyzable biodegradable linkages
include peptidic linkages cleavable by metalloproteinases and
collagenases and chitosan cleavable by lysozyme. Additional
illustrative degradable linkages include polymers and copolymers of
poly(hydroxy acid)s, poly(orthocarbonate)s, poly(anhydride)s,
poly(lactone)s, poly(amino acid)s, poly(carbonate)s,
poly(saccharide)s and poly(phosphonate)s. In certain embodiments,
the degradable linkage may contain ester linkages. Some
non-limiting examples include esters of succinic acid, glutaric
acid, propionic acid, adipic acid, or amino acids, as well as
carboxymethyl esters.
[0038] The ligand solution and gel can be sterilized by any known
method, e.g., irradiation, ethylene oxide, filtration in sterile
conditions on a 0.22 um filter and the like.
[0039] Medical gels herein may be used in a variety of
applications. In one embodiment, the gel is an uncured liquid,
functionalized with a plurality of reactive members of a binding
pair, which is applied and cured as a layer on surfaces of internal
organs or tissues which were pretreated with the complementary
reactive member as described above. The target tissue is pretreated
by spraying, painting or pouring a solution or suspension
containing the complementary reactive members of a binding pair on
to the tissue. Ligands associated with the reactive members or
complementary reactive members bind to their predetermined targets
on the tissue, thereby anchoring the reactive members or
complementary reactive members on the tissue. The uncured
functionalized liquid gel is sprayed over, e.g., a defect on the
tissue where it cures while simultaneously, the reactive members
and complementary reactive members of the specific binding pair
react specifically together to form covalent bonds, providing
adhesion between the tissue and the curing or cured gel. In another
embodiment, the functionalized gel is cured prior to application to
pretreated tissue and then draped over or otherwise contacted with
the target or defect to allow the covalent bond forming reaction to
occur with consequent covalent bonding and adherence. In certain
embodiments, two opposing tissue surfaces are pretreated and
functionalized, and functionalized gel added to form bonds to both
opposing surfaces.
[0040] Some applications include using the medical gel composition
to bind tissue together either as an adjunct to or as a replacement
of sutures, staples, tapes and/or bandages. In another application,
the present gels may be used to prevent post-surgical adhesions. In
this application, the gel, functionalized with a reactive member of
a binding pair, is applied and cured as a layer on surfaces of
internal organs or tissues which were pretreated with a
complementary reactive member of the binding pair as described
above in order to prevent the formation of adhesions at a surgical
site as the site heals. In another application, the functionalized
gel may be used to attach pretreated skin grafts and to position
pretreated tissue flaps or free flaps during reconstructive
surgery. In still another application, the functionalized gel may
be used to close pretreated gingival flaps in periodontal surgery.
Additional applications include sealing tissues to prevent or
control blood or other fluid leaks at suture or staple lines as
well as to prevent or control air leaks in the pulmonary
system.
[0041] In addition, functionalized medical gels herein can be used
as bulking agents, e.g., they can be injected via a syringe and
needle or other generally accepted means directly into a specific
area wherever a bulking agent is desired, i.e., a pretreated soft
tissue deformity such as that seen with areas of muscle atrophy due
to congenital or acquired diseases or secondary to trauma, burns,
and the like. An example of this would be the injection of a
medical gel herein in the upper torso of a patient with muscular
atrophy secondary to nerve damage. A medical gel herein can also be
injected as a bulking agent for hard tissue defects, such as bone
or cartilage defects, either congenital or acquired disease states,
or secondary to trauma, burns, or the like. An example of this
would be an injection into the area surrounding the skull where a
bony deformity exists secondary to trauma. The injection in these
instances can be made directly into the needed area with the use of
a needle and syringe under local or general anesthesia.
[0042] A medical gel could also be injected percutaneously by
direct palpation, such as by placing a needle inside a pretreated
vas deferens and occluding the same with the injected
functionalized bulking medical gel, thus rendering the patient
infertile. The gel could also be injected through a catheter or
needle with fluoroscopic, sonographic, computed tomography,
magnetic resonance imaging or other type of radiologic guidance.
This would allow for placement or injection of the pretreatment
formulation and subsequent functionalized medical gel either by
vascular access or percutaneous access to specific organs or other
tissue regions in the body, wherever a bulking agent would be
required.
[0043] Techniques of tissue engineering employing functionalized
medical gel scaffolds can be used to create alternatives to
prosthetic materials currently used in craniomaxillofacial surgery,
as well as formation of organ equivalents to replaced diseased,
defective, or injured tissues. Medical gels herein can be malleable
and used to encapsulate cells. To form a hydrogel containing the
cells, a functionalized polymer solution is mixed with the cells to
be implanted to form a suspension. Then, in one embodiment, the
target site is pretreated with complementary members of a specific
binding pair and the functionalized polymers in suspension are
injected directly into a patient prior to crosslinking of the
polymer to form the hydrogel containing the cells. The hydrogel
cures over a short period of time while simultaneously binding to
the pretreated area through covalent bond formation. In another
embodiment, the functionalized gel is injected or poured into a
mold, where it crosslinks to form a semi-solid hydrogel of the
desired anatomical shape having cells dispersed therein which then
may be implanted in a pretreated target area in a patient. The
hydrogel may be produced, for example, by cross-linking a
polysaccharide polymer by exposure to a monovalent cation. Other
polymers capable of forming functionalized hydrogels as described
above may be used as disclosed herein. In the embodiments where the
functionalized polymer is crosslinked by contact with a
crosslinking agent, the strength of the crosslink may be increased
or reduced by adjusting the concentration of the polymer and/or
crosslinking agent.
[0044] Further, combinations in accordance with this disclosure,
e.g., functionalized medical gel having reactive members of a
specific binding pair and functionalized pretreatment formulation
containing complementary members of the specific binding pair,
could be injected through a laparoscope or thoracoscope to any
intraperitoneal or extraperitoneal or thoracic organ. For example,
the functionalized pretreatment formulation and functionalized gel
could be injected in the region of the gastroesophageal junction
for the correcting of gastroesophageal reflux. This could be
performed either with a thoracoscope injecting the substances in
the esophageal portion of the gastroesophageal region, or via a
laparoscope by injecting the substances in the gastric portion of
the gastroesophageal region, or by a combined approach.
[0045] A kit for a functionalized adhesive herein includes a
medical gel which has a plurality of reactive members of a specific
binding pair adapted to be attached to a surface of the gel and an
applicator adapted to contain a solution or suspension of
complementary reactive members of the specific binding pair, the
complementary reactive members having a functionality that will
adhere them to biological tissue upon contact. The kit may
optionally include a container which contains a catalyst for
causing the reactive members of a specific binding pair to bind
with the complementary reactive members of the specific binding
pair. The catalyst may be a solution of metal such as copper. In
embodiments, the kit contains a microwave or ultraviolet radiation
generator.
[0046] It should be understood that variations can be made to the
above embodiments that are with the purview of ordinary skill in
the art. For example, other click chemistry reactions are suitable
for use herein, e.g., staudinger reaction of phosphines with alkyl
azides. Accordingly, those skilled in the art can envision
modifications which are included within the scope of the claimed
invention that are not expressly set forth herein.
* * * * *