U.S. patent application number 14/239049 was filed with the patent office on 2015-08-20 for biomaterial based on aligned fibers, arranged in a gradient interface, with mechanical reinforcement for tracheal regeneration and repair.
This patent application is currently assigned to THE UNIVERSITY OF KANSAS. The applicant listed for this patent is Michael Detamore, Lindsey Ott, Robert Weatherly. Invention is credited to Michael Detamore, Lindsey Ott, Robert Weatherly.
Application Number | 20150230918 14/239049 |
Document ID | / |
Family ID | 47715685 |
Filed Date | 2015-08-20 |
United States Patent
Application |
20150230918 |
Kind Code |
A1 |
Detamore; Michael ; et
al. |
August 20, 2015 |
BIOMATERIAL BASED ON ALIGNED FIBERS, ARRANGED IN A GRADIENT
INTERFACE, WITH MECHANICAL REINFORCEMENT FOR TRACHEAL REGENERATION
AND REPAIR
Abstract
An implant can include a plurality of polymeric fibers
associated together into a fibrous body. The fibrous body is
capable of being shaped to fit a tracheal defect and capable of
being secured in place by suture or by bioadhesive. The fibrous
body can have aligned fibers (e.g., circumferentially aligned) or
unaligned fibers. The fibrous body can be electrospun. The fibrous
body can have a first characteristic in a first gradient
distribution across at least a portion of the fibrous body. The
fibrous body can include one or more structural reinforcing
members, such as ribbon structural reinforcing members, which can
be embedded in the plurality of fibers. The fibrous body can
include one or more structural reinforcing members bonded to the
fibers with liquid polymer as an adhesive, the liquid polymer
having a substantially similar composition of the fibers.
Inventors: |
Detamore; Michael;
(Lawrence, KS) ; Ott; Lindsey; (Lawrence, KS)
; Weatherly; Robert; (Overland Park, KS) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Detamore; Michael
Ott; Lindsey
Weatherly; Robert |
Lawrence
Lawrence
Overland Park |
KS
KS
KS |
US
US
US |
|
|
Assignee: |
THE UNIVERSITY OF KANSAS
Lawrence
KS
|
Family ID: |
47715685 |
Appl. No.: |
14/239049 |
Filed: |
August 15, 2012 |
PCT Filed: |
August 15, 2012 |
PCT NO: |
PCT/US2012/050974 |
371 Date: |
January 5, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61523894 |
Aug 16, 2011 |
|
|
|
Current U.S.
Class: |
623/9 |
Current CPC
Class: |
A61L 27/18 20130101;
A61F 2250/0028 20130101; A61L 27/10 20130101; A61F 2/04 20130101;
A61L 2420/04 20130101; A61F 2/20 20130101; A61L 27/18 20130101;
A61L 27/34 20130101; A61L 27/14 20130101; C08L 67/04 20130101; A61F
2250/0018 20130101; A61L 2420/08 20130101; C08L 67/04 20130101;
A61L 27/34 20130101; A61F 2002/046 20130101; A61L 2300/414
20130101; A61L 2430/22 20130101; A61F 2210/0076 20130101 |
International
Class: |
A61F 2/20 20060101
A61F002/20; A61L 27/10 20060101 A61L027/10; A61L 27/14 20060101
A61L027/14 |
Goverment Interests
GOVERNMENT RIGHTS
[0002] This invention was made with government support under NSF
0847759 awarded by the National Science Foundation. The government
has certain rights in the invention.
Claims
1. An implant comprising: a plurality of elongate polymeric fibers
associated together into a fibrous body, the fibrous body having
the plurality of polymeric fibers being molded, bound, wound, or
electrospun together to form the fibrous body.
2. (canceled)
3. The implant of claim 1, the fibrous body having aligned
fibers.
4. The implant of claim 1, the fibrous body having unaligned
fibers.
5. The implant of claim 3, the fibrous body having
circumferentially aligned fibers.
6. (canceled)
7. The implant of claim 1, the fibrous body having a first
characteristic in a first gradient distribution across at least a
portion of the fibrous body.
8.-11. (canceled)
12. The implant of claim 1, wherein the fibrous body includes one
or more structural reinforcing members located within the fibrous
body and encapsulated by the plurality of polymeric fibers.
13. (canceled)
14. The implant of claim 12, wherein the structural reinforcing
members includes one or more circumferential structural reinforcing
members embedded in the fibrous body with an annular shape or
portion thereof.
15.-16. (canceled)
17. The implant of claim 12, wherein the one or more structural
reinforcing members include bioglass.
18. The implant of claim 1, wherein the fibrous body includes two
or more different fiber types with different characteristics,
wherein the different fiber types are distributed in two or more
gradient distributions.
19.-21. (canceled)
22. The implant of claim 18, wherein different fibers of have
different characteristics selected from type of composition; type
of polymer; fiber diameter size; fiber diameter size distribution;
type of bioactive agent in a fiber; type of bioactive agent
combination in a fiber; bioactive agent concentration in a fiber;
amount of bioactive agent in a fiber; rate of bioactive agent
release from a fiber; mechanical strength of a fiber; flexibility
of a fiber; rigidity of a fiber; color of a fiber;
radiotranslucency of a fiber; or radiopaqueness of a fiber.
23.-26. (canceled)
27. The implant of claim 1, wherein the fibrous body has a
plurality of distinct fiber layers of different types of fibers
from one side or end to another side or end.
28.-30. (canceled)
31. The implant of claim 1, wherein the fibrous body is a wound
fibrous body having: fibers of a first type at one or more inner
layers of the wound fibrous body; fibers of a second type
intermingled with the one or more inner layers of the fibers of the
first type adjacent to the one or more inner layers; fibers of the
second type at one or more second layers of the wound fibrous body
adjacent to the intermingled fibers.
32. The implant of claim 1, wherein the fibrous body a wound
fibrous body having in order from one side: fibers of a first type
at one or more inner layers of the wound fibrous body; fibers of a
second type intermingled with the one or more inner layers of the
fibers of the first type; fibers of the second type at one or more
second layers of the wound fibrous body; fibers of a third type or
the first type intermingled with one or more second layers of the
fibers of the second type; and fibers of the third type at one or
more third layers of the wound fibrous body.
33.-42. (canceled)
43. The implant of claim 1, wherein the fibrous body has different
types of fibers arranged so as to mimic collagen arrangement in
native tracheal cartilage, where outer superficial zones of the
implant mimic cartilage and has circumferentially aligned fibers
that mimic collagen fibers.
44.-55. (canceled)
56. A method of treating a tracheal defect, the method comprising:
providing an implant of claim 1; and implanting the tracheal
implant into a tracheal defect in a subject.
57. The method of claim 56, wherein the subject is a human or other
animal.
58. The method of claim 56, comprising implanting the tracheal
implant into a hole defect in the trachea.
59. The method of claim 56, comprising implanting the tracheal
implant in a circumferential tracheal defect.
60. The method of claim 56, comprising treating tracheal
stenosis.
61. The method of claim 56, comprising a medical professional
shaping the fibrous implant just before implantation to match a
defect.
62. The method of claim 56, comprising tracheal tissue
regeneration.
Description
CROSS-REFERENCE
[0001] This patent application claims the benefit of U.S.
Provisional Application Ser. No. 61/523,894, filed on Aug. 16,
2011, which provisional application is incorporated herein by
specific reference in its entirety.
BACKGROUND
[0003] Tracheal repair procedures date back to the late 19th
century. However, a predictably effective treatment is not
available to restore normal function to a stenotic (e.g., abnormal
narrowing) trachea without the use of an autologous tissue graft,
which results in the sacrifice of native tissue. Even with the use
of an autologous graft, the size, shape, and stiffness of the graft
is often not ideal. Countless tissue engineering and regenerative
medicine studies have attempted to regenerate tracheal tissue.
Thus, there remains a need in the art for improvement in artificial
tracheal implants
DESCRIPTION OF FIGURES
[0004] FIG. 1A includes a schematic representation of a
cross-sectional profile of an embodiment of fibrous implant.
[0005] FIG. 1B includes a schematic representation of the fibrous
implant of FIG. 1A.
[0006] FIG. 1C includes a schematic representation of an embodiment
of a fibrous implant.
[0007] FIG. 2A includes a schematic representation of an embodiment
of a fibrous implant having external structural reinforcing
members.
[0008] FIG. 2B includes a schematic representation of an embodiment
of a fibrous implant having sharp interfaces between different
fiber types.
[0009] FIG. 2C includes a schematic representation of an embodiment
of a fibrous implant having gradient interfaces between different
fiber types.
[0010] FIG. 3 includes an image of fibers associated with a
structural reinforcing member.
[0011] FIGS. 4A-4D include micrographs of tissue with respect to a
fibrous implant.
[0012] FIG. 5 illustrates a method of forming a fibrous implant
patch from a tubular fibrous implant.
[0013] FIG. 6A includes an image of aligned fibers of a fibrous
implant patch.
[0014] FIG. 6B includes an image of a fibrous implant patch of FIG.
6A implanted into a tracheal defect.
[0015] FIG. 7A includes a 3D rendering from microCT analysis of a
fibrous implant patch after six weeks in a rabbit trachea (anterior
view).
[0016] FIG. 7B includes a 3D rendering from microCT analysis of a
fibrous implant patch after six weeks in a rabbit trachea (lumen
view). Image demonstrates patch's ability to keep airway open.
[0017] FIG. 7C includes a photographic image of fibrous implant
patch after six weeks in a rabbit trachea.
DETAILED DESCRIPTION
[0018] In the following detailed description, reference is made to
the accompanying drawings, which form a part hereof. In the
drawings, similar symbols typically identify similar components,
unless context dictates otherwise. The illustrative embodiments
described in the detailed description, drawings, and claims are not
meant to be limiting. Other embodiments may be utilized, and other
changes may be made, without departing from the spirit or scope of
the subject matter presented herein. It will be readily understood
that the aspects of the present disclosure, as generally described
herein, and illustrated in the figures, can be arranged,
substituted, combined, separated, and designed in a wide variety of
different configurations, all of which are explicitly contemplated
herein.
[0019] Generally, the present invention includes fibrous
biomaterial compositions that are prepared with or without
mechanical reinforcement and that are suitable for use as implants.
The implants can be configured for tissue regeneration and repair
as well as for other uses. The implants can include biocompatible
fibers arranged in a manner that facilitates implantation in order
to promote biocompatibatility as well as cell or extracellular
matrix ingrowth into the implant between the fibers or to replace
degraded fibers. The implant can have aligned fibers to random
fibers, and can be configured for short or long term use, such as
by being biostable or biodegradable. The overall implant or
individual fibers can include or be devoid of polymeric coating
compositions over a structural core or thread or ribbon. The
individual fibers can be cylindrical polymers with regular or
irregular cross-sectional profiles. The individual fibers can
include active agents, such as antimicrobials or pharmaceuticals or
tissue growth factors. The fibers and fibrous implant can be
configured particularly for tracheal application, such as being
arranged together for use as a tracheal implant. The fibrous
implant may also be configured as other types of implants in other
applications, such as esophageal, intestinal, arterial, or other
body lumen or patch for a body lumen or tissue patch.
[0020] In one embodiment, the individual fibers can have a uniform
composition. For example, the fiber can be prepared from a
biocompatible material (e.g., biostable or biodegradable), such as
a polymer, metal, ceramic, glass, bioglass (e.g., biodegradable)
composite, alloy, or combination thereof.
[0021] In one embodiment, the individual fibers can be solid and
uniform, or have a core and shell cross-sectional profile. When
uniform, the fibers can have any of the properties described for a
core and/or shell. The core can be a structural material that
provides shape and structural properties to the fiber. The core can
be flexibly resilient, deformable, or rigid. The core can be
modified to have properties as desired so that the implant can
range from being malleable or deformable or bendable to shape-set
or rigid. The core can be a polymer, metal, ceramic, glass,
composite, alloy, or combination thereof, which is harder or more
rigid or more structurally sound compared to the shell. The core
can also include bioactive agents as described herein. The shell
can be a polymeric material that is commonly used for biomedical
applications on implants. The polymeric shell can encapsulate the
core. The polymeric shell can also include bioactive agents as
described herein. The shell can be a polymer, metal, ceramic,
glass, composite, alloy, or combination thereof, which is softer or
less rigid or more structurally sound compared to the shell.
[0022] The individual fibers can be prepared from polymeric
scaffold materials, such as materials that can be based on
polymeric electrospun fibers (e.g. polycaprolactone, or
poly(lactic-co-glycolic acid) that are fabricated to form an
implant in a graded-manner (i.e., gradual transition between two
polymeric layers) using a co-electrospinning technique. Other
examples of polymers that can be used for the fibers and implant
can include synthetic rubber, Bakelite, neoprene, nylon, PVC,
polystyrene, polyethylene, polyetheylene oxide, poly(ethylene
terephthalate), polylactate, polylactic acid, polyglyconate,
polyglycolic acid, polypropylene, polyacrylonitrile, PVB, silicone,
polydimethylsiloxane, polyurethane, and many more including blends
or combinations of any of these polymers. The polymers can be
biodegradable or biostable. The individual fibers or overall
implant can include bioactive material components (e.g., bioactive
glass strips), nanophase materials (e.g., chondroitin sulfate), or
proteins (e.g., growth factors like transforming growth factor beta
(TGF-beta) and epidermal growth factor (EGF)) as well as any
well-known component of a composition for implantation.
[0023] The fibrous implant can be shaped into various forms (e.g.,
tubular, sheets, patches). The fibrous implant can include shapes
that are solid through their core as well as hollow or luminal,
where the cross sectional profiles can include triangles, squares,
rectangles, rhombus, trapezoidal, and any other polygonal shape as
well as circular or oval shapes or combinations of polygons with
circular features.
[0024] The implant can be prepared from one type of fiber.
Alternatively, the implant can be prepared from two or more types
of fibers. The fibers can be arranged to have one type of fiber at
one end or on one side, and then have a different type of fiber on
the other end or other side. The implant can include one or more
different types of fibers between the first end and other end. Any
number of different types of fibers can be used. The different
fibers can be arranged with a sharp interface therebetween with one
type of fiber on one side of the sharp interface and a different
type of fiber on the other side of the interface. Alternatively,
the interface can be a gradient interface with corresponding
gradients of the different types of fibers. In one aspect, the
implant can have a first discrete portion with a first type of
fiber and a second discrete portion adjacent to the first discrete
portion with a sharp interface therebetween and where the second
discrete portion has a second type of fiber. Optionally, the first
discrete portion can be devoid of the second type of fiber, and/or
the second discrete portion can be devoid of the first type of
fiber. Alternatively, the first and second discrete portions can
have gradients of both types of fiber. In one aspect, the implant
can have two or more types of fibers where the fibers are arranged
in a gradient from one end to the other. That is, a fiber of a
first type can be on one side of the implant with a fiber of a
second type being on the opposite side of the implant such that a
gradient of the different types of fibers exists between the two
ends. Various gradients from one end or one side to an opposite end
or side can be prepared with different types of fibers. The
gradient can be linear, curved, arcuate, or parabolic.
[0025] In one embodiment, the fibers can be arranged in a manner
where fibers having a first characteristic are at a higher
concentration or amount at one side or end of the implant and a
lower concentration or amount at the other side or end of the
implant so as to form a gradient. The fiber gradient can be
constant, variable, parabolic, or the like. The fiber gradient may
also be from one portion within the implant to another portion
within the implant or to a side or end of the implant. For example,
the fiber gradient can be from one side or end to an internal
portion of the implant, such as a middle portion or center of the
implant (e.g., at a support member). A fiber gradient may also be
designed from one surface or end to a middle portion and then a
different or same type of fiber gradient to the opposite side or
end, which can be exemplified as a parabolic gradient. There may
also be more than one fiber characteristic with a gradient
distribution from one side or end to an opposite side or end. The
fiber gradients can be from different types of fibers with
different mechanical or chemical characteristics. The different
characteristics can be the presence or absence of active agents in
fibers to form one or more active agent gradients in the implant.
Instead of having a hard or sharp interface between fiber groups
with different characteristics, the different fibers can be
arranged in a gradual or gradient interface between them so that
the fibers with different characteristics are present in a gradient
distribution. The materials of the different fibers may also be
different, which can result in different degradation rates or
active agent release rates from the fiber materials.
[0026] In one embodiment, the implant having the fibers can have a
cross-sectional profile that includes the combined cross-sectional
profiles of the individual fibers. That is, the fibers can be
aligned so that the cross-sectional profile of the implant bisects
the individual fibers. The individual fibers can be arranged or
aligned as described herein. Also, the individual fibers can be
arranged in the implant in the manner, gradients, or other patterns
described in application Ser. No. 12/248,530 (hereinafter, the '530
application) for microspheres, which is incorporated herein by
specific reference in its entirety. That is, the fibers can be
arranged to provide the implant with a cross-sectional profile
according to the implants of the '530, where the fibers replace the
microparticles from one side to another side of the implant such as
described in any of FIGS. 2A-2D, 4A, 6A-6D, 7A-7C, or combinations
thereof. The fibers can be melded as described in the '530
application. Here, each fiber can extend from one end to another,
where the fibers are arranged in the gradient from one side to an
opposite side. The fibers may also be circumferentially aligned so
that the same fiber encircles the implant one or a plurality of
times.
[0027] The implant can be configured to be a functional tissue
engineered scaffold that harnesses gradient scaffold design and
drug delivery for tissue repair. One exemplary use described herein
includes using the implant having the fibers for tracheal defect
repair, where the fibers can be arranged circumferentially or in
the direction of collagen fibers of the trachea. The implant can be
pre-shaped or shaped in the operating room. The implant can be
prepared in various sizes to accommodate patients from fetal to
large adult sizes as well as for various sizes of defects or
tracheal holes that may form or be formed in the trachea. The
implant can be of a shape and dimension to be sufficient to be
placed into and fill a void in tracheal tissue. For example, a
surgeon can cut out the desired shape by a scalpel to provide a
custom shape, or a cookie-cutter type cutting device can be pressed
into the implant to provide a pre-determined shape. The surgeon can
then suture or otherwise implant the shaped implant to the trachea
in order to patch the tracheal defect. Alternatively, an adhesive,
such as a wound glue adhesive, can be used to adhere the implant to
the trachea.
[0028] In one embodiment, the implant can use biomaterials formed
into a biocompatible scaffold that does not use any donor tissue.
The implant can be manufactured at an industrial scale that
provides a deliverable end product with a fiber gradient that
provides a gradient of growth factors of a gradient of material
composition. The implant can be structurally self-supportive by the
fibers or it can be prepared to have some structural component that
reinforces the scaffold to provide the appropriate mechanical
integrity to keep the airway from closing. The individual fibers
can include a structural reinforcement member, such as a core,
shell, edge, or linear filament member. The individual fibers may
also be electrospun into an implant around or encapsulating a
structurally reinforcing member that is retained within the
implant. For example, a tube member of a certain material can be
used for structure, and the fibers can be electrospun around the
tube member, such as on the luminal wall and outer wall of the tube
so that the entire tube member is encapsulated by electrospun
fibers.
[0029] Preliminary studies have shown that rabbits survived and
grew new tissue over polycaprolactone (PCL) electrospun scaffolds
that were used to patch a trachea defect. Another implant may
include a faster degrading alternative to PCL. Also, gradients of
fast and slow degrading materials can be from side to side or from
a side to the middle of the implant. The electrospun fiber gradient
can be configured to allow greater tissue in-growth, while not
compromising the mechanical stability of the construct. This is
achieved by incorporating faster degrading polymers like
poly(lactic-co-glycolic acid) (PLGA) into the PCL using a
coelectrospinning process (e.g., using two or more syringes and
power supplies) to create multicomponent fibrous scaffolds.
[0030] Some exemplary novel and beneficial features of embodiments
of the fibrous implant include: the scaffolding material includes
aligned fibers (e.g., aligned electrospun fibers); the
microenvironment of the fibrous scaffold mimics native
extracellular matrix (ECM) and supports cell attachment,
differentiation, and growth; and circumferentially aligned fibers
mimic the collagen in native tracheal cartilage, where the outer
superficial zones of cartilage have circumferentially aligned
collagen fibers (which are active in tensile resistance). As such,
the implant can be configured to function as a native tracheal
segment with the fibers aligned similar to the collagen fibers of
the trachea. The fibers of the implant may also include collagen
coatings for enhanced biocompatibility. Collagen fibers may also be
used. Also, the method of manufacturing can include electrospinning
the fibers, which can be adapted to provide for a tracheal implant
having circumferentially aligned fibers, or aligned in any
manner.
[0031] While the present invention has been described as being
manufactured by electrospun fibers, other manufacturing methods can
be employed. For example, the individual fibers can be extruded and
bound at their ends to form an implant. Also, individual fibers can
be aligned and then coupled together at their ends and/or one or
more discrete locations along the aligned fibers. Extruded or
molded fibers may also be encapsulated in a polymeric coating.
Other manufacturing techniques may also be suitable for forming the
fibrous.
[0032] In one embodiment, the fibrous implant can include a
plurality of fibers in a multilayer, gradient design that simulates
the epithelium and cartilage layers in the trachea. That is, the
implant can include fibers aligned to simulate the epithelium and
fibers aligned to simulate the cartilage with a suitable interface
or gradient therebetween. In each layer or in each fiber of each
layer, specific polymers and bioactive components can be tailored
to meet the specific regeneration requirements of the tissue. For
example, PLGA can be used in the outer electrospun layers as the
faster degrading layer to allow for cells to colonize the scaffold;
while PCL, a slower degrading polymer, can be used in inner layers
of the scaffold to maintain structural integrity. Fibers or support
members having biodegradable glass or other biocompatible material
can be at a middle or center portion of the implant.
[0033] In one embodiment, the fibrous implant can include a
structural reinforcing member along with the fibers to provide for
further mechanical stability in the scaffold. For example, the
implant can include one or more bioactive glass strips that are
sufficient to withstand the tracheal compressive and tensile forces
and prevent against tracheal collapse. The bioactive glass strips
can be arranged circumferentially, longitudinally, diagonally,
helically, and/or be distributed evenly or randomly through the
scaffold. The bioactive glass strips can be distributed and
arranged so as to mimic the native cartilage rings. Also, the
bioactive glass can be tubular or annularly arranged with a
circumference that matches the trachea.
[0034] The implant can be used in cell culture to grow suitable
cells prior to implantation. The implant having cells or cell
cultures attached thereto can then be implanted into a subject.
Accordingly, the implant can be used with or without cells, and
does not require specialized surgical techniques or highly
invasive, multistage surgeries. This straightforward, highly
adaptable, patient-specific approach for a tracheal implant can
benefit medical practitioners and patients.
[0035] While the present implant having fibers (e.g., in a gradient
configuration) has been described for use in tracheal defect
repair, the implant may also be dimensioned, shaped, or otherwise
configured for implantation in other tissue engineering
applications (e.g., vascular tissue engineering), or possibly even
wound or tissue regeneration (e.g., skin, liver, etc.). Thus, the
technology of the fibrous implant is not limited in its focus, and
can be configured for any implant application. The fibrous implant
can be configured for use in patch tracheal defects and whole
circumferential defects, and thereby can be used as any patch or
for any body lumen. For example, non-reinforced implants may be
used for tracheal patches while reinforced implants can be used for
circumferential implants. The device can be enhanced in mechanical
performance by incorporating resilient materials such as bioactive
glass strips, sheets, or tubes, which serve to keep the biomaterial
structurally stable (i.e., prevent collapse).
[0036] In one embodiment, computer modeling can be used to design
an implant having a gradient in one or more characteristics. The
computer model can receive experimental or theoretical data and
design an implant that is suitable for the intended use. The
computer model can determine the best way to assemble the gradient
of fibers and when and where to include one or more bioactive or
structural materials in the fibers. The computer can then control
the electrospinning in order to prepare the fibrous implant. The
computer can be programafig.med to prepare the implant with certain
characteristics. Also, the computer can receive data of a subject
in need of an implant, and then determine the structure and fibers
and fiber gradients or sharp interfaces for the implant to match a
defect to be treated with the implant.
[0037] The fibrous implant can be provided in a generic shape, and
then a medical professional can pre-shape the implant before an
operation, or easily create custom shapes during surgery.
Pre-shaped fibrous implants can also be tailored and customized
before implantation. The generic shape can be a tube similar in
size and configuration to a trachea. The fibers of the implant can
extend from one end of the tube to the other end of the tube or be
circumferentially aligned or wound. The fibers can be wound
circumferentially similar to thread wound on a spool. The body of
the fibers can cooperatively form the luminal surface and outer
surface of the tubular generic shape. The implant can be sutured in
place and/or placed with a bioadhesive, or any other method of
implantation and securement commonly used for implants can be
used.
[0038] FIGS. 1A-1B illustrate an embodiment of a fibrous implant
100 in accordance with the principles described herein. The fibrous
implant 100 is shown to have a tubular body 110 with a lumen 112.
The tubular body 110 extends from a luminal wall 114 to an outer
wall 116. The tubular body 110 can also be considered to have one
side 118 and an opposite side 120. The tubular body 110 has a first
end 122 and an opposite second end 124. As shown in FIG. 1A, the
tubular body 110 is pointing out from the page with the first end
122 being viewable. The individual fibers 150 can be wound
circumferentially from the first end 122 to the second end 124 and
back, depending on the layer, as shown in FIG. 1B. FIG. 1A shows
the fibers 150 to be arranged around a support member 126. However,
the support member 126 can be optional. The tubular body 110 is
shown to have a first annular section 102 extending from the outer
wall 116 to the support member 126 and a second section 104
extending from the support member 126 to the luminal wall 114.
[0039] The first section 102 can be prepared from one or more
different types of fibers. For example, the first section 102 can
have a first type of fiber 128 adjacent to the outer wall 116 and a
second type of fiber 130 adjacent to the support member 126. The
interface 136 between the first type of fiber 128 and second type
of fiber 130 can be a hard interface or a gradient interface. In
the gradient interface 136, the first type of fibers 128 can fade
into the second type of fibers 130, and vice versa. As such, the
outer wall 116 can be mostly or all the first type of fibers 128
and adjacent to the support member 126 can be mostly or all second
type of fibers 130. Also, the second section 104 can be prepared
from one or more different types of fibers. For example, the second
section 104 can have a third type of fiber 132 adjacent to the
support member 126 and a fourth type of fiber 134 adjacent to the
luminal wall 114. The interface 138 between the third type of fiber
132 and fourth type of fiber 134 can be a hard interface or a
gradient interface. In the gradient interface 138, the third type
of fibers 132 can fade into the second type of fibers 134, and vice
versa. As such, the luminal wall 114 can be mostly or all the
fourth type of fibers 134 and adjacent to the support member 126
can be mostly or all third type of fibers 132.
[0040] In one aspect, the first type of fiber 128 and fourth type
of fiber 134 can be the same; however, they can be different. In
one aspect, the second type of fiber 130 and third type of fiber
132 can be the same; however, they can be different. In one aspect,
the first type of fiber 128 and third type of fiber 132 can be the
same; however, they can be different. In one aspect, the second
type of fiber 130 and fourth type of fiber 134 can be the same;
however, they can be different. Other permutations of fiber
distributions can also be used.
[0041] The support member 126 can be an annular member, tubular
member, or it can be a "C" shape or other suitable shape, such as a
helix, spiral, or the like. The support member 126 can be a single
piece or multiple pieces, as shown in FIG. 2A below. The support
member 126 can be on the luminal wall 114 or outer wall 116 instead
of being embedded within the fibers 150. The support member 126 can
be a plurality of rigid fibers aligned with the other fibers 150.
The support member 126 can be omitted, such as when one or more of
the fibers 150 or fiber types are sufficient for structural
integrity for use as an implant. Such structural integrity can be
sufficient for being used as a tracheal implant.
[0042] While the fibrous implant 100 is shown to be tubular, any
other shape can be used. The fibrous implant 100 can be solid or
hollow. The fibrous implant 100 can have a cross-sectional profile
that is circular, triangle, square, rectangular, or other polygon
shape that is hollow with a lumen or solid without a lumen. In one
embodiment, the fibrous body can have the shape of a tube, sheet,
"C", diamond, rounded diamond, polygon, circular, or oval shape or
irregular shape. In one aspect, the fibrous body can have an
irregular shape designed to conform to a correspondingly shaped
tracheal defect. The fibrous body can have a predefined shape. In
one aspect, the fibrous body is sized for a fetus or infant or
child to adolescent or teen or young adult or small adult or
average male or female adult or large adult or an animal. Fibrous
composition can be prepared as any type of implant in any shape
that is suitable to be prepared from fibers. A coating can be
applied to the outside of the implant to contain the fibers
therein. Also, the fibers can be adhered together. Additionally,
the fibers can be melded together with a solvent. In any event, the
fibers can be bound together to form a three-dimensional implant.
The fiber gradient can be with respect to the inner wall 114 and/or
outer wall 116 or support member 126. The fiber gradient can be
with respect to the first side 118 or second side 120. The fiber
gradient can be with respect to the first end 122 or second end
124.
[0043] In FIGS. 1A-1B, one of the polymers can be PLGA while the
other is PCL. For example, the fibers adjacent to the lumen or
outside can be PLGA while the fibers adjacent to the support member
can be PCL. The support member can be a bioactive glass ribbon.
[0044] FIG. 1C shows a fibrous implant 160 in the form of a solid
three-dimensional block 162. The block 162 can have a first side
164 and an opposite second side 166, and have a top side 168 and
opposite bottom side 170. The fibers 150 can extend from a first
end 172 to opposite second end 174. The fibers 150 can have first
fiber ends 152 and opposite second fiber ends 154. The block 162
can have the fibers 150 arranged with a first type of fiber 150a at
the first side 164, where the first type of fibers 150a form a
first portion 176. The block 162 can have the fibers 150 arranged
with a second type of fiber 150b at the second side 166, where the
second type of fibers 150b form a second portion 180. A third
portion 178 is positioned between the first portion 176 and second
portion 180. The third portion 178 can include a third type of
fiber or it can be a gradient distribution of the first type of
fiber 150a and second type of fiber 150b. For example, in the third
portion 178, the first type of fiber 150a can have a higher
concentration adjacent to the first portion 176 and lower
concentration adjacent to the second portion 180, and the second
type of fiber 150b can have a higher concentration adjacent to the
second portion 180 and lower concentration adjacent to the first
portion 176.
[0045] FIG. 2A illustrates another embodiment of a fibrous implant
200 with a tubular body 210 with a lumen 212, which has a support
member 226 on the outer wall 216. While five different support
members 226 are shown, any number can be used, and positioned at
any location with gaps 206 or adjacent or touching. The tubular
body 210 can include a first section 208a, second section, 208b,
and third section 208c, each section having a different type of
fiber, or the second section 208b can be a blend of the fibers of
the first section 208a and the third section 208c. The support
member 226 can be an annular member, or it can be a "C" shape or
other suitable shape, such as a spiral, or the like. The support
member 226 can be bioactive glass ribbons, which can have a
rectangular cross section, be long and straight, and be capable of
springing back to being straight if bent and released. The support
member 226 can be about 800 .mu.m wide (e.g., or +/15%, 10%, or
20%), 100 .mu.m thick (e.g., or +/15%, 10%, or 20%), and vary in
length (e.g., 8-10 cm) (e.g., or +/15%, 10%, or 20%). To mimic the
rabbit trachea, where cartilage rings are very narrow (.about.1 mm)
and closely spaced (.about.1 mm in between), the support member 226
ribbons can be spaced 1 mm apart from each other along the length.
The ribbons can be wrapped around the construct and secured with
liquid PCL solution (see FIG. 3).
[0046] FIG. 2B shows a portion of an embodiment of the fibrous
implant 200 that can be used. The fibrous implant 200 is shown to
have an inner wall 214 and outer wall 216. The fibrous implant 200
is shown to have a first section 202 extending from the outer wall
216 to the support member 226 and a second section 204 extending
from the support member 226 to the inner wall 214. The first
section 202 can have a first type of fiber 228 adjacent to the
outer wall 216 and a second type of fiber 230 adjacent to the
support member 226. The interface 236 between the first type of
fiber 228 and second type of fiber 230 is a sharp interface, such
that there is substantially none of the first type of fiber 228
mixed with the second type of fiber 230. Also, the second section
204 can have a third type of fiber 232 adjacent to the support
member 226 and a fourth type of fiber 234 adjacent to the inner
wall 214. The interface 238 between the third type of fiber 232 and
fourth type of fiber 234 is a sharp interface, such that there is
substantially none of the third type of fiber 232 mixed with the
fourth type of fiber 234.
[0047] FIG. 2C shows a portion of another embodiment of the fibrous
implant 200 that can be used. The fibrous implant 200 is shown to
have an inner wall 214 and outer wall 216. The fibrous implant 200
is shown to have a first section 202 extending from the outer wall
216 to the support member 226 and a second section 204 extending
from the support member 226 to the inner wall 214. The first
section 202 can have a first type of fiber 228 adjacent to the
outer wall 216 and a second type of fiber 230 adjacent to the
support member 226. A gradient interface 240 is located between the
first type of fiber 228 and second type of fiber 230 such that
there is first type of fiber 228 mixed with the second type of
fiber 230 in gradients. Also, the second section 204 can have a
third type of fiber 232 adjacent to the support member 226 and a
fourth type of fiber 234 adjacent to the inner wall 214. A gradient
interface 242 is located between the third type of fiber 232 and
fourth type of fiber 234 such that there is third type of fiber 232
mixed with the fourth type of fiber 234 in gradients. The gradients
can be linear or curved as shown in the '530 application.
[0048] The fibrous body can include one or more different types of
fibers, such as at least two different types of fibers, or a
plurality of different types of fibers that are aligned in the same
direction. The fibrous body can have a first type of fiber having a
first characteristic in a first gradient distribution across at
least a portion of the fibrous body. A second type of fiber can
have a second characteristic in a second gradient, which second
gradient can be opposite of the first gradient. The different
characteristics an include type of composition; type of polymer;
fiber diameter size; fiber diameter size distribution; type of
bioactive agent in a fiber; type of bioactive agent combination in
a fiber; bioactive agent concentration in a fiber; amount of
bioactive agent in a fiber; rate of bioactive agent release from a
fiber; mechanical strength of a fiber; flexibility of a fiber;
rigidity of a fiber; color of a fiber; radiotranslucency of a
fiber; or radiopaqueness of a fiber. Some preferred examples of
different characteristics can be different fibers having different:
bioactive agents; antimicrobial agents; pharmaceuticals; structural
reinforcing members; polymer type; fiber type; cell types attached
to the fibers; fiber compositions thereof, and combinations
thereof. In one aspect, the fibrous body can include different
fibers with two or more characteristics in two or more gradient
distributions or varying gradient distributions. In one aspect, the
fibrous body can have a higher concentration of fibers having one
or more characteristics on one side or end of the body than in the
center and/or on an opposite side or end of the body. In one
aspect, the fibrous body can have a higher concentration of fibers
with one or more active agents on one side or end of the body than
in the center and/or on an opposite side or end of the body. In one
aspect, the fibrous body can have a higher concentration of fibers
with structural reinforcing members, structural reinforcing fibers,
or structural reinforcing members on one side or end of the body
than in the center and/or on an opposite side or end of the body,
or the reinforcing members can be centered or between the sides or
ends of the body. In one aspect, the fibrous body can have PCL
fibers in one gradient distribution and PLGA in another
distribution.
[0049] In one embodiment, the implant can include a plurality of
fibers forming an implant body having: a first set of fibers having
a first gradient spatial distribution with a higher concentration
at the first end and lower concentration at the second end of the
body; and a second set of fibers that are different from the first
set of fibers, the second set of fibers having a second gradient
spatial distribution with a lower concentration at the first end
and higher concentration at the second end of the body. In one
aspect, the first gradient spatial distribution and second gradient
spatial distribution blend into each other. In one aspect, the
fibrous implant can include: a first portion at the first end
having a majority of fibers of the first set; and a second portion
at the second end having a majority of fibers of the second set. In
one aspect, the fibrous implant can include: a first portion at the
first end having a majority of fibers of the first set; a second
portion at the second having a majority of fibers of the second
set; and a third portion disposed between the first portion and the
second portion, wherein the first gradient spatial distribution in
the third portion forms a first concentration gradient of the first
set of fibers and the second gradient spatial distribution in the
third portion forms a second concentration gradient of the second
set of fibers. In one aspect, the fibrous implant can include a
first bioactive agent contained in or disposed on the first set of
fibers, and the second set of fibers being substantially devoid of
the first bioactive agent. In one aspect, the fibrous implant can
include a first bioactive agent contained in or disposed on the
first set of fibers, and a second different bioactive agent
contained in or disposed on the second set of fibers. In one
aspect, the plurality of fibers include polymeric fibers or having
polymeric coatings that electrospun or melded together. In one
aspect, at least one of the first set or second set of fibers is
comprised of a biodegradable polymer, such PLGA. In one aspect, the
fibrous implant can include live cells and a medium sufficient for
growing the cells disposed in the interstitial spaces between the
fibers. In one aspect, a first bioactive agent is contained in or
disposed on the fibers of the first set, and a second different
bioactive agent is contained in or disposed on the fibers of the
second set. For example, the first bioactive agent can be an
osteogenic factor and the second bioactive agent can be a
chondrogenic factor. In another aspect, the different fibers can
have a transforming growth factor (TGF)-.beta..sub.3 and/or of
epidermal growth factor (EGF) or keratinocyte growth factor (KGF)
or vascular endothelial growth factor (VEGF). In one aspect, the
first set of fibers have a first characteristic and are devoid of a
second different characteristic, and the second set of fibers
having the second different characteristic and are devoid of the
first characteristic.
[0050] In one embodiment, the fibrous implant can include a
plurality of live cells attached to the plurality of fibers. The
cells can be any type of animal cell, such as human cells, or even
cells of the subject to receive the fibrous implant. The fibrous
implant can include a first cell type associated with a first set
of fibers, and a different second cell type associated with a
second set of fibers.
[0051] In one embodiment, a method of preparing tissue engineering
scaffold for growing cells can be performed with the fibrous
implant. The method can include: providing a first set of fibers;
providing a second set of fibers different from the first set of
fibers; and combining (e.g., electrospining) the fibers of the
first set and second set together so as to form a body. However,
the fibers can be prepared during the electrospining process, where
a first composition is prepared into the first set of fibers and a
second composition is prepared into the second fibers. Some of the
fibers can be prepared so as to degrade over time. Also, some of
the fibers can be prepared so as to release the bioactive agents to
promote healing or tissue ingrowth into the fibrous implant. Multi
layered and gradient scaffolds can be fabricated using a
co-electrospinning process with two or more syringes in
programmable syringe pumps.
[0052] In one embodiment, the fibrous body can have individual
fibers with a first characteristic, wherein the fibers are arranged
in a first gradient distribution across at least a portion of the
fibrous body. In one aspect, the fibrous body can have different
types of fibers having different characteristics with a fiber with
one characteristic having a first gradient distribution with
respect to one side or end of the implant and a different fiber
having a second characteristic having a second gradient
distribution with respect to a second side or end of the implant.
In one aspect, the fibrous body can have different fibers having
different characteristics with a fiber with one characteristic
having a first gradient distribution with respect to a center point
or plane of the implant and a fiber with a second characteristic
having a second gradient distribution with respect to a side or end
of the implant. Accordingly, the fibrous body can have a plurality
of fiber layers from one side or end to another side or end. Each
fiber layer can have a different type of fiber.
[0053] In one embodiment, the fibrous body can be formed so as to
have fibers wound (e.g., substantially circumferentially) around a
spool to form a wound fibrous body. The spool can be removed to
form a tubular implant. The fibrous body can have fibers of a first
type at one or more inner layers of the wound fibrous body and
fibers of a second type at one or more layers of the wound fibrous
body adjacent to the one or more inner layers. In one aspect, the
fibers can be longitudinally aligned. Alternatively, the fibers can
be laterally aligned. The fibers can be diagonally or helically
aligned. In one aspect, the fibrous body can be formed so as to
have fibers wound around a spool to form a wound fibrous body, with
the fibrous body having: fibers of a first type at one or more
inner layers of the wound fibrous body; fibers of a second type
intermingled with the one or more inner layers of the fibers of the
first type; and fibers of the second type at one or more second
layers of the wound fibrous body adjacent to the one or more inner
layers. In one aspect, the fibrous body can be formed so as to have
fibers wound around a spool to form a wound fibrous body, with the
fibrous body having: fibers of a first type at one or more inner
layers of the wound fibrous body; fibers of a second type
intermingled with the one or more inner layers of the fibers of the
first type; fibers of the second type at one or more second layers
of the wound fibrous body adjacent to the one or more inner layers;
fibers of a third type or the first type intermingled with one or
more second layers of the fibers of the second type; and fibers of
the third type at one or more third layers of the wound fibrous
body adjacent to the one or more second layers.
[0054] In one embodiment, the fibrous body can have the fibers
aligned from top to bottom (e.g., superoinferiorly) with respect to
implantation orientation of an upright subject. In one aspect, the
fibrous body can have the fibers aligned from side to side (i.e.,
mediolaterally at the anterior aspect of the trachea; in the
transverse plane) with respect to implantation orientation of an
upright subject.
[0055] In one embodiment, the fibrous body can have void space
sufficient for culturing cells within the implant or on one or more
fibers. This can be from selective degradation of the fibers, laser
etching after formation of the fibrous body, forming pores with
solvent, or by the interstitial spaces between adjacent fibers.
Also, the void space can form over time after implantation. The
void space can include a cell culture media in in vitro
application. The void space can include cells in in vitro or in
vivo applications.
[0056] In one embodiment, the fibrous body can have one or more
elongate structural members arranged at from about 0 degrees to
about 90 degrees with respect to the aligned fibers, such as at
about 10, 20, 30, 40, 45, 50, 60, 70, about 80 degrees. The angle
can be made with respect to a longitudinal axis of the fibrous
implant, a plurality of the fibers, direction of aligned fibers, or
with respect to a single fiber. The direction of orientation can be
the longitudinal axis of the trachea or circumferentially, and the
structural members can be angled therewith.
[0057] In one example, the fibers can be aligned and arranged so as
to mimic collagen arrangement in native tracheal cartilage.
However, the fibers can also be random, unaligned, diagonally
aligned, crisscrossed, helical, orthogonal, spun, woven, or other
pattern. In one aspect, one or more of all of the fibers can be
circumferentially aligned. In one aspect, the fibrous body can
include different types of aligned fibers arranged so as to mimic
collagen arrangement in native tracheal cartilage, where outer
superficial zones of the implant mimic cartilage and has
circumferentially aligned fibers that mimic collagen fibers. In one
aspect, the fibrous body can include different types of aligned
fibers arranged in multiple layers so as to mimic and/or promote
regeneration of epithelium and cartilage layers in the trachea. In
one aspect, one or more of all of the fibers are not aligned. In
one aspect, one or more of the fibers can run circumferentially or
laterally or longitudinally with respect to an upright position of
a subject
[0058] In one embodiment, the fibrous body can include fibers that
are active in tensile resistance. As such, a force can be applied
to opposite ends of the fibers. The fibers can be longitudinally
stretched. As a baseline comparison, mechanical studies of the
trachea have provided tensile moduli ranging from 0.3 to 14 MPa,
and circumferentially aligned electrospun PCL and PLGA fibers have
ranged from 10-45 MPa. The values can be modified when bioglass is
used as a support member.
[0059] In one embodiment, the implant can include one or more
fibers that has a core and shell cross-sectional profile. In one
aspect, one or more fibers can have a core and multiple shells
cross-sectional profile. The fibers can also be solid or a single
material. The fibers can be tubular and hollow with an internal
lumen. The fibers can have a cross-sectional profile dimension
ranging from about 1 mm to about 50 mm in diameter, from about 2 mm
to about 25 mm, from about 5 mm to about 20 mm, from about 8 mm to
about 15 mm, or about 12 mm in diameter.
[0060] While a fibrous implant is described herein, it should be
recognized that the implant can be a pre-implant or a generic shape
that can be modified prior to implantation. That is, a scaffold,
such as a tissue engineering scaffold for in vivo or in vitro
applications, having the fibers arranged as described herein that
is not implanted or prior to implantation can be considered to be a
fibrous implant, and the features of the fibrous implant apply to
pre-implant scaffolds as well as tissue engineering scaffolds.
[0061] In one embodiment, the fibrous implant having the features
or characteristics described herein can be manufactured. A method
of manufacturing a fibrous implant can include electrospinning
fibers so as to form the electrospun fibrous body. The fibers can
be electrospun to have a first characteristic in a first gradient
distribution. The fibers can be electrospun to have a second
characteristic in a second gradient different from the first
characteristic and/or first gradient. In one aspect, the method of
manufacture can include preparing the materials or compositions for
the electrospun fibers and/or formation of the fibers therefrom.
The method can include electrospinning an inner layer of fibers,
and electrospinning one or more layers over the inner layer.
[0062] In one embodiment, the method of manufacture can include
electrospinning the fibers around one or more structural
reinforcing members (e.g., support member). The method can include
placing circumferential structural reinforcing members around an
electrospun layer, and electrospinning a layer of fibers over the
reinforcing members. The method can include electrospinning one or
more layers of aligned fibers around one or more circumferentially
or longitudinally aligned elongate structural reinforcing members.
Also, both the fibers and structural reinforcing members can be
circumferentially orientated or longitudinally oriented. The
structural reinforcing member can be bioactive glass. The
cross-sectional dimensions of the bioactive glass reinforcing
member can range from about 2 mm to about 25 mm in diameter, from
about 5 mm to about 20 mm, from about 8 mm to about 15 mm, or about
12 mm. In one aspect, the implant can be configured with sufficient
structural reinforcement members for functionality without
collapsing or restenosis. In one aspect, the structural reinforcing
members can hold the implant in shape and provide for resiliency
for the implant to spring back to shape if deformed.
[0063] FIG. 5 illustrates a method 500 of manufacturing an implant.
The top panel shows a tubular implant 510, which can be cut 512
into a patch 514. The tubular implant 510 can be the same as the
implant 100 of FIGS. 1A-1B. The tubular implant 510 is cut along
line 182 to form the body 180 of the patch 514. Here, the patch 514
is shown to have one side 118a and an opposite side 120a, and a
first end 122a and an opposite second end 124a. The first end 122a
or second end 124 can be the top or bottom of the patch 514 when
implanted.
[0064] In one embodiment, the method of manufacture can include
sterilizing the implant. Any method of sterilization can be used.
For example, alcohol or other solvent can be used for
sterilization. In another example, the implant can be subjected to
heat and/or pressure for sterilization.
[0065] In one aspect, the fibrous body can be analyzed after
manufacture. This can include analysis of the alignment pattern
(e.g., circumferential alignment or non-alignment) of the fibers.
The analysis can be performed as known in the art or described
herein.
[0066] The fibrous implants can be configured for use as implants
in any location within the body. However, the fibrous can be
especially suitable for patch or circumferential implants for body
lumens, such as the trachea, esophagus, intestine, or the like.
While tracheal embodiments as described, the use can be applied to
other body lumens.
[0067] In one embodiment, the fibrous implant can be used in a
method of treating a tracheal defect. Such as method can include
providing a tracheal implant as described herein, and implanting
the tracheal implant into a tracheal defect in a subject. The
subject can be a human or other animal. The implant can be shaped
for a tracheal defect, and implanted into a defect in the trachea.
The defect can be a circumferential defect, and the implant can be
implanted in the circumferential tracheal defect. In one aspect,
the defect can be a hole, and the implant can be used for patching
the hole defect, such as for treating tracheal stenosis. The defect
can be natural, an injury, or surgically prepared. The implant can
be used for tracheal tissue regeneration.
[0068] In one aspect, a medical professional can custom shape the
tracheal implant to match the defect. This can include providing an
implant of any shape having fibers with any degree of alignment or
random alignment to a medical professional where the medical
professional shapes the implant prior to implantation.
[0069] The interface between the fibers and the support member can
vary. In one instance, the fibers can be bonded to the support
member, such as with melting, melding, adhesive or the like. In
another instance, the fibers can encapsulate the support member.
When the support member is bioglass, the fibers can be spun around
the bioglass for encapsulation. Also, liquid polymer, such as the
same or different polymer from the fibers, can be applied to the
bioglass and fibers to promote association by the liquid polymer
solidifying. FIG. 3 illustrates an example of an interface between
the fibers and bioglass, where the arrow shows association of the
fibers with the bioglass. FIG. 3 is an SEM image of bioglass ribbon
(bulk object) encased in PCL fibers (thin spaghetti-like fibers).
Liquid PCL was used to secured bioglass to fibers at contact points
(see arrow). As such, the bioglass strips can be encapsulated
within the fibrous sheets. The bioglass can also be encapsulated
with PLGA or other polymers.
[0070] In one embodiment, one or more fibers can have chondroitin
sulfate, while other fibers may or may not have chondroitin
sulfate. The application of chondroitin sulfate in electrospun
scaffolds can be useful.
[0071] In one embodiment, the fibers can be electrospun so as to be
circumferentially oriented to mimic the tracheal structure. The
circumferentially-oriented polymer fibers can be cut, placed, and
sutured into a defect. Rings of bioactive glass can be used to
reinforce the electrospun fiber scaffold to provide the mechanical
integrity. The implant can have a circumferential fiber structure
of the native trachea collagen from the electrospun fibers in the
circumferential orientation as well as the rings of the native
trachea mimicked by the bioactive glass ribbons also in the
circumferential orientation. The fibers can be spun to form
gradients in order to accelerate regeneration as the different
fibers of the different gradients can have different
characteristics. For example, one fiber can be configured for
regenerating cartilage-like tissue and another for regenerating
ciliated epithelium, where the different fibers fade as gradients
into each other from one side of the implant to the other. When the
implant is cylindrical or cut from a cylindrical member, the fibers
can have axial gradients from an outer surface to luminal wall, and
vice versa. The gradients can also extend from a wall to an
internal support member. The fiber gradients can provide gradient
concentrations of transforming growth factor (TGF)-.beta..sub.3
(e.g., outer wall layers) for chondrogenesis and epidermal growth
factor (EGF) (e.g., inner or luminal wall layers) for
epithelialization. The implant can be properly implanted with these
orientations of these types of fibers. In one aspect, the fibrous
implant can be seeded and/or cultured with bone marrow derived
mesenchymal stem cells (BMSCs) and/or umbilical cord mesenchymal
stromal cells (UCMSCs) or different gradients thereof. The gradient
distribution of the fibers with different growth factors provides a
release gradient so that the different growth factors are released
and present in the subject in the gradient distribution. The fibers
can be loaded with various amounts of TGF-.beta..sub.3 and/or EGF
(e.g., 0, 1, or 10 ng of growth factor per 1 mg of polymer, such as
PLGA). However, the fibrous implant can be with or without growth
factors or with or without cells.
[0072] FIG. 4A shows H&E stain for PCL only fibers, which shows
cell infiltration from both sides. FIG. 4B shows Collagen II IHC
for a trilayer scaffold without growth factors (GFs). FIG. 4C is a
microCT of a trilayer scaffold with GFs, which show the open airway
and regenerated defect (arrow). FIG. 4D shows collagen II IHC for
gradient scaffold with GFs, which shows complete coverage of
cartilage-like tissue (collagen II IHC, brown/red color--grey in
grayscale) on the outside of the PCL (black) here, and normal
ciliated epithelium lining the lumen of the scaffold in all groups.
Particularly, FIG. 4A shows the feasibility of the fibrous implant,
and shows cell infiltration with electrospun PCL scaffolds after 7
weeks. Additional studies were done for 6 weeks, which include the
data of: FIG. 4B shows the trilayer fibrous implant (e.g.,
PLGA-PCL-PLGA) scaffolds without growth factors; the trilayer
scaffolds with growth factors (TGF-.beta..sub.3 encapsulated in the
outer PLGA layer and EGF in the inner layer) in FIG. 4C; and
gradient scaffolds with growth factors in FIG. 4D. The data shows
complete coverage of cartilage-like tissue (collagen II
immunostaining) and ciliated epithelium with the addition of PLGA
and growth factors in FIG. 4D. The microCT scans revealed
acceptable narrowing of the trachea through the grafted sections,
but not severe stenosis. From gross examination of the tracheas,
scaffolds retained their shape and no air leaks or collapse was
evident. Tissue sections revealed the presence of PCL and almost
complete resorption of PLGA, as expected. As such, the growth
factors can be released faster from the PLGA on a shorter
time-scale (e.g., about 4 weeks), and for the PLGA to be degraded
and replaced by tissue regeneration, while slower degrading PCL
(e.g., about 2 years) and bioactive glass can provide structural
support to ensure long-term success of the implant.
[0073] The fibrous scaffolds used for implantation can have varied
properties, from different fibers, such as in different
distributions or gradient distributions. The fibrous scaffolds can
be modulated in terms of mechanical integrity, porosity,
degradation profiles, and growth factor release profiles and
bioactivity. Table 1 provides some examples of variations in the
fibers and fibrous scaffold.
[0074] In one embodiment, the electrospun fibrous implant can be
substantially devoid of pores or opening from the outer wall to
luminal wall. Regarding porosity, the lower porosities associated
with aligned electrospun fibers are advantageous for tracheal
regeneration as a means to maintain an airtight scaffold.
[0075] The fibrous implant can be configured to provide desirable
contraction, agent release profiles, mechanical integrity, and/or
degradation. The variables that can be modulated can include:
fibers that include collagen, poly(L-lactide-co-caprolactone), or
other similar materials in place of or blended in with PLGA and/or
PCL, 2); modified bioative glass composition (Table 3) or
dimensions; a fiber bilayer; growth factors adsorbed or immobilized
to the surface of the fibers, coaxially electrospun into the center
of the fibers, or growth-factor-loaded microparticles could be
encapsulated into the fibers; polymeric layer thickness can be
modified; degradation rates of the polymers can be easily altered
by changing the intrinsic viscosity (i.e., changing the molecular
weight) or by changing the lactic acid to glycolic acid ratio in
the PLGA; bioactive glass degradation rate can be controlled by
altering the composition; and excipients can be included for growth
factor stabilization, including magnesium hydroxide, sucrose,
PF-127, trehalose, polyethylene glycol, magnesium carbonate,
cyclodextrins, or the like. Table 2 shows variations of the types
of fibers, growth factors, and/or cells that can be used in the
scaffolds. Table 3 shows variations in the bioactive glass
compositions that can be used, with 13-93 being preferred with
13-93B3 being second preferred.
TABLE-US-00001 TABLE 1 Material Growth Group Gradient? Factors?
Glass? Layer Thicknesses.sup..sctn. (mm) Single-layer PCL N/A No No
PCL = 1.0 Single-layer PCL + Glass N/A No Yes PCL = 1.0 Tri-layer
No No No PLGA/PCL/PLGA = PLGA/PCL/PLGA 0.50/1.00/0.50 Tri-layer +
GFs No Yes No PLGA/PCL/PLGA = PLGA + EGF/PCL/PLGA + 0.50/1.00/0.50
TGF-.beta..sub.3 Gradient* Yes No No PLGA/gradient/PCL/gradient/
PLGA/gradient/PCL/gradient/ PLGA = 0.25/0.50/0.50/0.50/0.25 PLGA
Gradient* + GFs Yes Yes No PLGA/gradient/PCL/gradient/ PLGA +
EGF/gradient/PCL/ PLGA = 0.25/0.50/0.50/0.50/0.25 gradient/PLGA +
TGF-.beta..sub.3 Gradient* + Glass Yes Yes Yes
PLGA/gradient/PCL/gradient/ PLGA + EGF/gradient/PCL/ PLGA =
0.25/0.50/0.50/0.50/0.25 gradient/PLGA + TGF-.beta..sub.3
.sup..dagger-dbl.Mechanical testing, degradation, and porosity will
be measured only on groups with no growth factors.
.sup..sctn.Layered scaffolds are 2.0 mm in total thickness.
Diameter of the aluminum collecting mandrel is 5 mm. *"Gradient"
refers to a gradual, linear transition between layers, as opposed
to a sharp interface.
TABLE-US-00002 TABLE 2 Factor # of levels Description of levels
Scaffold 6 PCL only Design PLGA/PCL/PLGA tri-layer PLGA/PCL/PLGA
tri-layer + growth factors PLGA/PCL/PLGA gradient + growth factors
PLGA/PCL/PLGA gradient + bioactive glass + growth factors
PLGA/PCL/PLGA gradient + bioactive glass + growth factors + CS Cell
2 hBMSCs or hUCMSCs (normal or CFE enriched*) Type
TABLE-US-00003 TABLE 3 Glass SiO.sub.2 B.sub.2O.sub.3 Na.sub.2O
K.sub.2O MgO CaO P.sub.2O.sub.5 45S5 45.0 0 24.5 0 0 24.5 6.0
13-93* 53.0 0 6.0 12.0 5.0 20.0 4.0 13-93B1 35.33 17.67 6.0 12.0
5.0 20.0 4.0 13-93B3* 0 53.0 6.0 12.0 5.0 20.0 4.0
[0076] FIGS. 6A-6B show an embodiment of a fibrous implant (FIG.
6A) and implantation thereof (FIG. 6B). The fibrous scaffold was
fabricated using a rotating mandrel to create circumferential
alignment of electrospun PCL fibers. A high degree of electrospun
fiber orientation can provide cell alignment in the direction of
fiber orientation. Prior to implantation, the scaffold were imaged
with SEM (FIG. 6A). The biomaterial graft was sterilized, and a
pre-sized piece was placed over an induced elliptical-shaped defect
(FIG. 6B) in the anterior tracheal wall, as well as subcutaneously.
After 7 weeks, the rabbits (n=2) were euthanized and the tracheas
and subcutaneous implants were collected for analysis. At the
conclusion of the study, the tracheas were prepared and sectioned
for histological staining (H&E) after being imaged using
computer tomographic (CT) imaging. Prior to implantation, scaffolds
exhibited fiber alignment (FIG. 6A). During the 7 weeks in vivo,
the animals ate and breathed normally with no complications. From
gross examination of the tracheas after week 7, the constructs
appeared to be covered with vascularized tissue and no air leaks or
collapse were evident. The CT scans revealed slight narrowing of
the trachea through the grafted sections (FIG. 6B), but no severe
stenosis. Sections of the tissue revealed the presence of PCL as
expected, and cell infiltration into the scaffold. Based on these
preliminary results, we have established that these scaffolds were
biocompatible and were rigid enough to keep the trachea patent. The
scaffold maintained its shape and minimal degradation of the
scaffold material was observed. After implanting manufactured PCL
scaffolds into elliptical-shaped defects in rabbit tracheas for 7
weeks, the scaffolds maintained a robust, airtight trachea free of
any breathing distress, and exhibited evidence of cell infiltration
into the scaffold and tissue regeneration.
[0077] FIG. 7A-7C show results of fibrous implant patch in rabbit
trachea after 6 weeks. FIG. 7A includes a 3D rendering from microCT
analysis of a fibrous implant patch after six weeks in a rabbit
trachea (anterior view). FIG. 7B includes a 3D rendering from
microCT analysis of a fibrous implant patch after six weeks in a
rabbit trachea (lumen view). Image demonstrates patch's ability to
keep airway open. FIG. 7C includes a photographic image of fibrous
implant patch after six weeks in a rabbit trachea. Three
experimental groups were fabricated: trilayer
[poly(lactic-co-glycolic acid) (PLGA)-polycaprolactone (PCL)-PLGA]
scaffolds without growth factors, trilayer scaffolds with growth
factors (transforming growth factor-.beta..sub.3 encapsulated in
the outer PLGA layer and epidermal growth factor in the inner
layer), and gradient scaffolds with growth factors. The scaffolds
were fabricated using a rotating mandrel to create aligned
electrospun fibers. Prior to implantation, scaffolds were imaged
with SEM. The biomaterial grafts were sterilized, and pre-sized
pieces were placed over an induced elliptical-shaped defect in the
anterior tracheal wall of New Zealand White rabbits (two rabbits
per group, six rabbits total). After 6 weeks, the rabbits were
euthanized and the tracheas and subcutaneous implants were
collected for analysis. At the conclusion of the study, the
tracheas were prepared and sectioned for histological and
immunohistochemical staining after being imaged using microCT
imaging. During our 6 week in vivo study, the rabbits ate and
breathed normally with no complications. None of the rabbits had
any obvious stridor. The microCT scans revealed minimal narrowing
of the trachea through the grafted sections, but not severe
stenosis. From gross examination and microCT analysis of the
tracheas, scaffolds retained their shape and no air leaks or
collapse were evident (FIG. 7A-C). After implanting manufactured
scaffolds into elliptical-shaped defects in rabbit tracheas for 6
weeks, the scaffolds maintained a robust, airtight trachea allowing
the animals to be free of any breathing distress. The implanted
material exhibited evidence of cell infiltration into the scaffold,
tissue regeneration, and re-epithelialization of the lumen.
[0078] Based on the results, we have established that these fibrous
scaffolds are biocompatible and are rigid enough to keep the
trachea patent. The scaffold maintained its shape and minimal
degradation of the scaffold material was observed. Because of PCL's
slow degradation profile, a faster degrading alternative to PCL,
such as PLGA can be used to allow tissue in-growth, while not
compromising the mechanical stability of the construct. Two types
of fibers can be prepared into a scaffold having a gradient of PLGA
and PCL. The co-electrospinning process, with two or more syringes
and power supplies, can be used to create multicomponent fibrous
scaffolds.
[0079] The present disclosure is not to be limited in terms of the
particular embodiments described in this application, which are
intended as illustrations of various aspects. Many modifications
and variations can be made without departing from its spirit and
scope, as will be apparent to those skilled in the art.
Functionally equivalent methods and apparatuses within the scope of
the disclosure, in addition to those enumerated herein, will be
apparent to those skilled in the art from the foregoing
descriptions. Such modifications and variations are intended to
fall within the scope of the appended claims. The present
disclosure is to be limited only by the terms of the appended
claims, along with the full scope of equivalents to which such
claims are entitled. It is to be understood that this disclosure is
not limited to particular methods, reagents, compounds compositions
or biological systems, which can, of course, vary. It is also to be
understood that the terminology used herein is for the purpose of
describing particular embodiments only, and is not intended to be
limiting.
[0080] With respect to the use of substantially any plural and/or
singular terms herein, those having skill in the art can translate
from the plural to the singular and/or from the singular to the
plural as is appropriate to the context and/or application. The
various singular/plural permutations may be expressly set forth
herein for sake of clarity.
[0081] It will be understood by those within the art that, in
general, terms used herein, and especially in the appended claims
(e.g., bodies of the appended claims) are generally intended as
"open" terms (e.g., the term "including" should be interpreted as
"including but not limited to," the term "having" should be
interpreted as "having at least," the term "includes" should be
interpreted as "includes but is not limited to," etc.). It will be
further understood by those within the art that if a specific
number of an introduced claim recitation is intended, such an
intent will be explicitly recited in the claim, and in the absence
of such recitation no such intent is present. For example, as an
aid to understanding, the following appended claims may contain
usage of the introductory phrases "at least one" and "one or more"
to introduce claim recitations. However, the use of such phrases
should not be construed to imply that the introduction of a claim
recitation by the indefinite articles "a" or "an" limits any
particular claim containing such introduced claim recitation to
embodiments containing only one such recitation, even when the same
claim includes the introductory phrases "one or more" or "at least
one" and indefinite articles such as "a" or "an" (e.g., "a" and/or
"an" should be interpreted to mean "at least one" or "one or
more"); the same holds true for the use of definite articles used
to introduce claim recitations. In addition, even if a specific
number of an introduced claim recitation is explicitly recited,
those skilled in the art will recognize that such recitation should
be interpreted to mean at least the recited number (e.g., the bare
recitation of "two recitations," without other modifiers, means at
least two recitations, or two or more recitations). Furthermore, in
those instances where a convention analogous to "at least one of A,
B, and C, etc." is used, in general such a construction is intended
in the sense one having skill in the art would understand the
convention (e.g., "a system having at least one of A, B, and C"
would include but not be limited to systems that have A alone, B
alone, C alone, A and B together, A and C together, B and C
together, and/or A, B, and C together, etc.). In those instances
where a convention analogous to "at least one of A, B, or C, etc."
is used, in general such a construction is intended in the sense
one having skill in the art would understand the convention (e.g.,
"a system having at least one of A, B, or C" would include but not
be limited to systems that have A alone, B alone, C alone, A and B
together, A and C together, B and C together, and/or A, B, and C
together, etc.). It will be further understood by those within the
art that virtually any disjunctive word and/or phrase presenting
two or more alternative terms, whether in the description, claims,
or drawings, should be understood to contemplate the possibilities
of including one of the terms, either of the terms, or both terms.
For example, the phrase "A or B" will be understood to include the
possibilities of "A" or "B" or "A and B."
[0082] In addition, where features or aspects of the disclosure are
described in terms of Markush groups, those skilled in the art will
recognize that the disclosure is also thereby described in terms of
any individual member or subgroup of members of the Markush
group.
[0083] As will be understood by one skilled in the art, for any and
all purposes, such as in terms of providing a written description,
all ranges disclosed herein also encompass any and all possible
subranges and combinations of subranges thereof. Any listed range
can be easily recognized as sufficiently describing and enabling
the same range being broken down into at least equal halves,
thirds, quarters, fifths, tenths, etc. As a non-limiting example,
each range discussed herein can be readily broken down into a lower
third, middle third and upper third, etc. As will also be
understood by one skilled in the art all language such as "up to,"
"at least," and the like include the number recited and refer to
ranges which can be subsequently broken down into subranges as
discussed above. Finally, as will be understood by one skilled in
the art, a range includes each individual member. Thus, for
example, a group having 1-3 cells refers to groups having 1, 2, or
3 cells. Similarly, a group having 1-5 cells refers to groups
having 1, 2, 3, 4, or 5 cells, and so forth.
[0084] From the foregoing, it will be appreciated that various
embodiments of the present disclosure have been described herein
for purposes of illustration, and that various modifications may be
made without departing from the scope and spirit of the present
disclosure. Accordingly, the various embodiments disclosed herein
are not intended to be limiting, with the true scope and spirit
being indicated by the following claims. All references recited
herein are incorporated herein by specific reference in their
entirety.
* * * * *