Biomimetic scaffolds for peripheral nerve injuries

Abstract

Disclosed herein is a biomimetic scaffold for neural tissue growth having multiple microchannels arranged within a sheath. Each microchannel includes a porous wall formed from a biocompatible and biodegradable material. The biocompatible and biodegradable material can be poly(ethylene glycol) diacrylate, methacrylated gelatin, methacrylated collagen, or polycaprolactone, and combinations thereof. The biomimetic scaffold has a high open volume percentage that allows for excellent (linear, high-fidelity) neural tissue growth while minimizing inflammation near the implantation site in vivo.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62 / 832,681, filed April 11, 2019, the entire contents of which are incorporated herein by reference.

[0002] Technical Field The present disclosure relates to biomimetic scaffolds incorporating porous microchannels for promoting neural tissue growth and methods for manufacturing such scaffolds. [Background technology]

[0003] Although the peripheral nervous system (PNS) has a greater regenerative capacity than the central nervous system (CNS), functional regeneration after injury is largely incomplete when damaged axons become displaced or lose contact with innervated tissues, resulting in major functional deficits, including insufficient reinnervation of target tissues and painful neuroma formation.

[0004] Factors that influence PNS regeneration include the nature and extent of the injury itself, the duration of denervation, the type and diameter of the injured nerve fiber, and age. Proximal nerve injuries or complete transections with large nerve gaps generally result in poorer outcomes, with minimal clinically meaningful motor and sensory recovery. Several reasons contributing to suboptimal recovery have been identified, including: 1) insufficient axonal regrowth rates; 2) leakage into other environments permissive for axonal outgrowth; 3) alterations in the target tissue or pathways to reach the target tissue; 4) excessive and chronic neuroinflammation; and 5) Schwann cell atrophy and dysfunction.

[0005] Currently, the standard of clinical practice for surgical repair of peripheral nerve interfaces (PNIs), which are large gaps in peripheral nerves, involves the placement of autologous nerve grafts. Disadvantages of autologous grafts include: 1) donor site morbidity, 2) limited supply of donor grafts, and 3) increased surgical time and complexity.

[0006] Experimental development of scaffolds to direct peripheral nerve repair has resulted in commercially available nerve guides, but these single-channel nerve guides provide only one large-diameter tube, resulting in misalignment of regenerating axons with their appropriate targets. When implanted into a transected rat sciatic nerve model, such open-tube single-channel nerve guide scaffolds unfortunately result in many axons losing their linear orientation along their proximal end, just 200 μm after entering the scaffold, before reaching their distal end. This results in low axon density, and some axons that reach the distal end lose their orientation even as they exit the distal nerve. This misguided axon guidance can potentially cause pain due to neuroma.

[0007] Recently, cellular approaches involving the development of Schwann cell-filled conduits have been somewhat successful, as Schwann cells naturally assist axonal regeneration by guiding and supporting axonal growth, but these cells have not been translated for human peripheral nerve injury.

[0008] Furthermore, there are no effective treatments to promote regeneration after either acute or chronic spinal cord injury (SCI) in humans. Various experimental methods promote axonal regeneration in SCI animal models, including cell transplantation into the injury site to support axonal attachment and outgrowth. Transplanted cells include astrocytes, Schwann cells, bone marrow stromal cells, or stem cells. However, a drawback of cell implants is the lack of three-dimensional (3D) organization, which results in irregular axonal growth direction, and most axons do not regenerate beyond the injury site into host tissue, resulting in minimal, if any, functional recovery.

[0009] Thus, there remains a need to identify strategies and techniques to enhance the extent, speed, guidance, targeting, and injury distance over which neural tissue (e.g., axons) can regenerate. Summary of the Invention [Means for solving the problem]

[0010] Disclosed herein is a nerve repair scaffold comprising: a sheath having a proximal end and a distal end; a plurality of microchannels disposed in the sheath and traversing the sheath from the proximal end to the distal end, wherein the microchannels are configured to allow neural tissue growth; and a first protrusion at the proximal end and a second protrusion at the distal end, wherein the first protrusion and the second protrusion are configured to suture neural tissue.

[0011] Also disclosed herein is a nerve repair scaffold comprising a sheath having a proximal end and a distal end, a plurality of microchannels disposed in the sheath and traversing the sheath from the proximal end to the distal end, wherein the microchannels are configured to allow neural tissue to grow therethrough, and wherein at least one of the microchannel walls comprises a biofunctional agent incorporated into the microchannel wall.

[0012] Also disclosed herein is a nerve repair scaffold comprising a sheath having a proximal end and a distal end, a plurality of microchannels disposed in the sheath and traversing the sheath from the proximal end to the distal end, wherein the microchannels are configured to allow neural tissue to grow through them, a first protrusion at the proximal end and a second protrusion at the distal end, wherein the first protrusion and the second protrusion are configured to suture neural tissue, wherein the scaffold further comprises a biofunctional agent, wherein each of the microchannels has an open diameter of about 200 μm to about 350 μm, and wherein the scaffold is prepared from about 15% to about 25% poly(ethylene glycol) diacrylate and about 1-7% methacrylated gelatin.

[0013] Also disclosed herein is a method of restoring nerve function comprising implanting the nerve repair scaffold disclosed herein at the site of nerve injury in a subject in need thereof, thereby allowing restoration of nerve function across the injury site. [Brief explanation of the drawings]

[0014] [Figure 1]FIG. 1 is a perspective view of a scaffold as disclosed herein featuring close-packed hexagonal channels. [Figure 2] FIG. 1 shows a cross-section of a scaffold as disclosed herein, featuring close-packed hexagonal channels. [Figure 3] FIG. 1 shows a side view of a scaffold as disclosed herein featuring close-packed hexagonal channels. [Figure 4] FIG. 1 is a perspective view of another embodiment of a scaffold as disclosed herein, featuring a circular channel. [Figure 5] FIG. 10 shows a cross-sectional view of another embodiment of a scaffold as disclosed herein, featuring a circular channel. [Figure 6] FIG. 10 is a side view of another embodiment of a scaffold as disclosed herein, featuring a circular channel. [Figure 7] Cross-sectional image showing densely packed hexagonal microchannels in a biomimetic scaffold. [Figure 8] A scaffold that holds sutures. [Figure 9] Figure 9 shows a scaffold as disclosed herein implanted into a rat sciatic nerve sectioned at 1 cm, 4 weeks after implantation. 9A shows regenerating axons that are misaligned and barely reach the distal end of the injured nerve in a control animal without an implanted scaffold. 9B shows regenerating axons guided by the disclosed multi-channel scaffold to reach the distal end of the injured nerve. [Figure 10] Improved connectivity of spinal motor neurons to peripheral muscles in animals using the disclosed multi-channel scaffolds. [Figure 11] Improved function of neurons in animals implanted with the disclosed multi-channel scaffolds as evidenced by a significant increase in muscle weight compared to open-tube implants. [Figure 12] Intact sciatic and sural nerves in a rat preparation. [Figure 13] A multi-channel scaffold as provided herein placed across the sciatic nerve gap. DETAILED DESCRIPTION OF THE INVENTION

[0015] In native peripheral nerves, axons are clustered together in bundles. A transection injury to a peripheral nerve disrupts this structure. In cases of injury to peripheral nerves (such as the median nerve) where a gap exists that prevents the two nerve stumps from being closed directly with sutures, bridging is necessary. The disclosed multi-channel biomimetic scaffold can bridge the nerve injury and provide guidance for axonal growth across the injury site. The microchannels of the disclosed scaffold organize the axons and maintain the fidelity of regeneration. Thus, the scaffold keeps them at the same coordinates in space and guides them along the same path to the opposite side of the injury site.

[0016] In some embodiments, a scaffold of the desired length is 3D printed and then placed at the injury site. The proximal and distal nerve stumps are then inserted into the protrusions of the scaffold, where they are aligned with the microchannel scaffold. The epineurium is then sutured to the protrusions or sheaths, thereby securing the scaffold in place. Regenerating axons from the proximal side enter the scaffold and are guided through the injury site to the distal nerve stump. In some embodiments, the channels of the scaffold are filled with Schwann cells to further support axon regeneration. In some embodiments, neurotrophic factors (such as bone-derived neurotrophic factor [BDNF] or nerve growth factor [NGF]) or drug delivery particles can be encapsulated inside the scaffold walls for controlled release.

[0017] After severe trauma, the nervous system does not spontaneously regenerate and requires intervention to restore function. There is a need for the development of materials that enable the fabrication and implementation of improved and more effective neural guidance scaffolds. In various aspects, the present disclosure contemplates improved and more effective tissue scaffolds for promoting neural tissue growth and proliferation in a subject. The subject may be an animal with a complex nervous system, such as a mammal, such as a human, a primate, or a companion animal. Accordingly, a tissue scaffold according to the present disclosure may be a device implanted in such a subject.

[0018] 1-3 illustrate a scaffold 100 according to one embodiment of the disclosed biomimetic scaffold described herein. The scaffold 100 includes a sheath (or outer wall) 102. Disposed within the sheath 102 are a plurality of hexagonal microchannels 104. Each of the hexagonal microchannels 104 can include a channel wall 106 and an open lumen 108. In some embodiments, the hexagonal microchannels have more uniform and thinner walls than round or circular microchannels, leaving more space for axons to penetrate and regenerate. Certain embodiments exhibit as few as seven perfect hexagons throughout a given scaffold inner diameter 110. Other embodiments can have 200 or more perfect hexagons within the inner diameter.

[0019] The scaffold 100 can have an outer diameter 112 and an inner diameter 110. The scaffold 100 can further include a first protrusion 114 on a proximal end 116 and a second protrusion 118 on a distal end 120. The first protrusion 114 and / or the second protrusion 118 can be used for suturing to neural tissue. Including the first protrusion 114 and the second protrusion 118, the scaffold 100 can have an overall length 120 including the protrusions.

[0020] 4-6 show another embodiment of a biomimetic scaffold 200 as described herein. Scaffold 200 includes a sheath (or outer wall) 202. Disposed inside sheath 202 are multiple circular microchannels 204. Each of the circular microchannels can include a channel wall 206 and an open lumen 208. In some embodiments, the circular microchannels are uniform, even with thinner walls, leaving space for axons to penetrate and regenerate. Certain embodiments exhibit as few as 50 complete microchannels throughout a given scaffold inner diameter 210. Other embodiments can have 200 or more complete microchannels within the inner diameter.

[0021] The scaffold 200 can have an outer diameter 212 that complements the inner diameter 210. The scaffold 200 can further include a first protrusion 214 on a proximal end 216 and a second protrusion 218 on a distal end 220. The first protrusion 214 and / or the second protrusion 218 can be used for suturing to neural tissue. Including the first protrusion 214 and the second protrusion 218, the scaffold 200 can have an overall length 222 including the protrusions.

[0022] By "microchannel" is meant that the structure defines a distinct longitudinal axis and has an open lumen or a hollow core. In some embodiments, the microchannel is hexagonal or round in shape. In some embodiments, the microchannel can have other generally round or circular shapes or other rectilinear shapes (such as, but not limited to, hexagonal, round, triangular, rectangular, square, pentagonal, heptagonal, octagonal, nonagonal, decagonal, oval, trapezoidal, or other shapes). In some embodiments, the microchannel is substantially round. In some embodiments, the scaffold comprises a composite of microchannel shapes, e.g., a composite of pentagonal and hexagonal microchannels. Such a microchannel with a distinct longitudinal axis comprises an elongated axial dimension that is longer than the other dimensions (e.g., diameter or width) of the channel. Thus, an elongated microchannel is linear.

[0023] 7 and 8 show general features of a scaffold as described herein, including protrusions, microchannels, and walls.

[0024] In some embodiments, the proximal and distal ends of the scaffold feature "protrusions" consisting of sheaths that extend from the microchannels to provide a substrate for suturing to the nerve, as shown in the figures and described above. In other embodiments, the protrusions may be omitted. The protrusions can have a length of about 0.1 mm to about 3 mm to allow the medical professional sufficient material to suture the nerve. In some embodiments, the thickness of the protrusions is about 1 mm to about 3 mm. In some embodiments, the thickness of the protrusions is about 0.1 mm to about 3 mm.

[0025] Thus, the present disclosure contemplates a scaffold comprising a plurality of microchannels, each defining a major longitudinal axis. According to certain variations of the present disclosure, the "microchannels" preferably have at least one spatial dimension of less than about 1,000 μm. In certain embodiments, each microchannel has an inner diameter of about 10 μm to about 1,000 μm, optionally about 10 μm to about 500 μm, optionally about 50 μm to about 450 μm, and optionally about 50 μm to about 300 μm.

[0026] In some embodiments, the microchannel has an open diameter of about 200 μm to about 500 μm, e.g., about 300 μm. In some embodiments, the microchannel has an open diameter of about 200 μm, about 300 μm, about 400 μm, or about 500 μm. In some embodiments, the microchannel has an open diameter of about 150 μm to about 250 μm. In some embodiments, the microchannel has an open diameter of about 170 μm to about 230 μm. In some embodiments, the microchannel has an open diameter of about 180 μm to about 220 μm. In some embodiments, the microchannel has an open diameter of about 190 μm to about 210 μm. In some embodiments, the microchannel has an open diameter of about 200 μm to about 350 μm. The open diameter refers to the diameter of the lumen of the microchannel. In some embodiments, the wall thickness is about 10 μm to about 50 μm. In some embodiments, the microchannel wall thickness is from about 10 μm to about 60 μm. In some embodiments, the microchannel wall thickness is less than 60 μm, less than 50 μm, less than 40 μm, less than 30 μm, or less than 20 μm. In some embodiments, the microchannel wall thickness is from about 10 μm to about 60 μm, from about 10 μm to about 50 μm, from about 10 μm to about 40 μm, from about 10 μm to about 30 μm, or from about 10 μm to about 20 μm.

[0027] For example, depending on the application, microchannels according to certain variations of the present disclosure may have lengths of from about 500 μm to about 30 cm, optionally from about 500 μm to about 10 cm, and in certain variations, optionally, by way of non-limiting example, from about 500 μm to about 3 cm. In some embodiments, the scaffold may be 0.5 mm to 10 cm in length. In some embodiments, the scaffold may be 5 mm to 10 cm in length. In some embodiments, the scaffold may be up to 15 cm in length. In some embodiments, the scaffold length is from about 0.5 cm to about 10 cm. In some embodiments, the length of the scaffold is from about 0.5 cm to about 1 cm, from about 0.5 cm to about 2 cm, from about 0.5 cm to about 3 cm, from about 0.5 cm to about 5 cm, from about 0.5 cm to about 7 cm, from about 0.5 cm to about 9 cm, from about 0.5 cm to about 10 cm, from about 1 cm to about 2 cm, from about 1 cm to about 3 cm, from about 1 cm to about 5 cm, from about 1 cm to about 7 cm, from about 1 cm to about 9 cm, from about 1 cm to about 10 cm , about 2 cm to about 3 cm, about 2 cm to about 5 cm, about 2 cm to about 7 cm, about 2 cm to about 9 cm, about 2 cm to about 10 cm, about 3 cm to about 5 cm, about 3 cm to about 7 cm, about 3 cm to about 9 cm, about 3 cm to about 10 cm, about 5 cm to about 7 cm, about 5 cm to about 9 cm, about 5 cm to about 10 cm, about 7 cm to about 9 cm, about 7 cm to about 10 cm, or about 9 cm to about 10 cm. In some embodiments, the scaffold length is about 0.5 cm, about 1 cm, about 2 cm, about 3 cm, about 5 cm, about 7 cm, about 9 cm, or about 10 cm. In some embodiments, the scaffold length is at least about 0.5 cm, about 1 cm, about 2 cm, about 3 cm, about 5 cm, about 7 cm, or about 9 cm. In some embodiments, the length of the scaffold is at most about 1 cm, about 2 cm, about 3 cm, about 5 cm, about 7 cm, about 9 cm, or about 10 cm. In some embodiments, the length of the scaffold is from about 0.1 cm to about 15 cm. In some embodiments, the length of the scaffold is from about 5 cm to about 15 cm. In some embodiments, the length of the scaffold is at least 5 cm.

[0028] The outer diameter of the scaffold can be about 1.5 mm to about 10 mm, or any diameter between 1.5 mm and 10 mm. In some embodiments, the outer diameter of the scaffold is about 1.5 mm to about 10 mm. In some embodiments, the outer diameter of the scaffold is about 1.5 mm to about 2.5 mm, about 1.5 mm to about 3.5 mm, about 1.5 mm to about 4.5 mm, about 1.5 mm to about 5 mm, about 1.5 mm to about 5.5 mm, about 1.5 mm to about 6 mm, about 1.5 mm to about 7 mm, about 1.5 mm to about 8 mm, about 1.5 mm to about 9 mm, about 1.5 mm to about 10 mm, about 2.5 mm to about 3.5 mm, about 2.5 mm to about 4.5 mm, about 1.5 mm to about 5 mm, about 1.5 mm to about 6 mm, about 1.5 mm to about 7 mm, about 1.5 mm to about 8 mm, about 1.5 mm to about 9 mm, about 1.5 mm to about 10 mm, about 2.5 mm to about 3.5 mm, about 2.5 mm to about 4.5 mm, about 1.5 mm to about 5 mm, about 1.5 mm to about 5. ... mm, about 2.5 mm to about 5 mm, about 2.5 mm to about 5.5 mm, about 2.5 mm to about 6 mm, about 2.5 mm to about 7 mm, about 2.5 mm to about 8 mm, about 2.5 mm to about 9 mm, about 2.5 mm to about 10 mm, about 3.5 mm to about 4.5 mm, about 3.5 mm to about 5 mm, about 3.5 mm to about 5.5 mm, about 3.5 mm to about 6 mm, about 3.5 mm to about 7 mm, about 3.5 mm to about 8 mm, about 3.5 mm to about 9 mm, about 3.5 mm to about 10 mm, about 4.5 mm to about 5 mm, about 4.5 mm to about 5.5 mm, about 4.5 mm to about 6 mm, about 4.5 mm to about 7 mm, about 4.5 mm to about 8 mm, about 4.5 mm to about 9 mm, about 4.5 mm to about 10 mm, about 5 mm to about 5.5 mm, about 5 mm to about 6 mm, about 5 mm to about 7 mm, about 5 mm to about 8 mm, about 5 mm to about 9 mm, about 5 mm to about 10 mm, 5.5 mm to about 6 mm, about 5.5 mm to about 7 mm, about 5.5 mm to about 8 mm, about 5.5 mm to about 9 mm, about 5.5 mm to about 10 mm, about 6 mm to about 7 mm, about 6 mm to about 8 mm, about 6 mm to about 9 mm, about 6 mm to about 10 mm, about 7 mm to about 8 mm, about 7 mm to about 9 mm, about 7 mm to about 10 mm, about 8 mm to about 9 mm, about 8 mm to about 10 mm, or about 9 mm to about 10 mm. In some embodiments, the outer diameter of the scaffold is about 1.5 mm, about 2.5 mm, about 3.5 mm, about 4.5 mm, about 5 mm, about 5.5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, or about 10 mm.In some embodiments, the outer diameter of the scaffold is at least about 1.5 mm, about 2.5 mm, about 3.5 mm, about 4.5 mm, about 5 mm, about 5.5 mm, about 6 mm, about 7 mm, about 8 mm, or about 9 mm. In some embodiments, the outer diameter of the scaffold is at most about 2.5 mm, about 3.5 mm, about 4.5 mm, about 5 mm, about 5.5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, or about 10 mm. In some embodiments, the outer diameter of the scaffold is between 0.5 mm and 10 mm. In some embodiments, the outer diameter of the scaffold is between 0.1 mm and 10 mm. In some embodiments, the outer diameter of the scaffold is between 0.5 mm and 20 mm, between 0.5 mm and 30 mm, between 0.5 mm and 40 mm, or between 0.5 mm and 50 mm. In some embodiments, the outer diameter of the scaffold is between 0.5 mm and 20 mm.

[0029] The microchannels are formed from a biocompatible and biodegradable material, such as a biocompatible polymer. For example, the scaffold structure can include microchannels formed from a biocompatible and biodegradable polymer, such as a polyester polymer. Biodegradable and biocompatible polymers suitable for forming the microchannels include polyethylene glycol, gelatin, or collagen, as well as derivatives and mixtures thereof. In certain aspects, the biocompatible and biodegradable material is selected from the group of polymers consisting of poly(ethylene glycol) diacrylate, methacrylated gelatin, and methacrylated collagen, as well as combinations thereof. In other embodiments, the scaffold structure can be composed of other polymeric materials, such as polycaprolactone or acrylated polycaprolactone. In some embodiments, different portions of the scaffold structure can have different material compositions than other portions of the scaffold structure (e.g., in one non-limiting embodiment, the inner microchannels can be composed of a mixture of methacrylated gelatin and polyethylene glycol, while the outer sheath can be composed of polycaprolactone). In some embodiments, the scaffold is fabricated from a mixture of different polymerizable materials, such as those listed above. For example, a scaffold according to the present disclosure can be prepared from a mixture of poly(ethylene glycol) diacrylate and methacrylated gelatin. In some embodiments, the mixture may further include a suitable initiator for the polymerization reaction, such as, for example, lithium phenyl-2,4,6-trimethylbenzoylphosphinate. Any initiator suitable for initiating the polymerization reaction can be used. In some embodiments, the remainder of the mixture for producing the scaffold is a suitable solvent, such as an aqueous solvent or buffer (e.g., phosphate-buffered saline (PBS) or Dulbecco's phosphate-buffered saline (DPBS)).

[0030] In some embodiments, the scaffold is made from a mixture comprising poly(ethylene glycol) diacrylate and methacrylated gelatin. In some embodiments, the scaffold is made from about 25% poly(ethylene glycol) diacrylate (average size Mn 700) and about 1-7% methacrylated gelatin. In some embodiments, the scaffold is made from a mixture comprising about 15%, about 17.5%, about 20%, about 22.5%, about 25%, about 27.5%, about 30%, about 32.5%, or about 35% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is made from a mixture comprising about 22.5% to about 27.5%, about 20% to about 30%, about 17.5% to about 32.5%, or about 15% to about 35% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is made from a mixture containing about 25% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is made from a mixture containing about 15% to about 30% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is made from a mixture containing about 20% to about 25% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is made from a mixture containing about 15% to about 25% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is made from a mixture containing about 20% to about 30% poly(ethylene glycol) diacrylate. In some embodiments, the average molecular weight of the poly(ethylene glycol) diacrylate is about Mn 550, about Mn 700, about Mn 1000, about Mn 2000, or about Mn 4000. In some embodiments, the average molecular weight of the poly(ethylene glycol) diacrylate is about Mn 500 to about Mn 1000. In some embodiments, the average molecular weight of the poly(ethylene glycol) diacrylate is about Mn 700. In some embodiments, the average molecular weight of the poly(ethylene glycol) diacrylate is about 100 Mn to 10,000 Mn. In some embodiments, the scaffold is made from a mixture containing about 1-7% methacrylated gelatin.In some embodiments, the scaffold is fabricated from a mixture comprising about 1-7%, about 2-6%, or about 3-5% methacrylated gelatin. In some embodiments, the scaffold is fabricated from a mixture comprising about 1-15% methacrylated gelatin. In some embodiments, the scaffold is fabricated from a mixture comprising poly(ethylene glycol) diacrylate and methacrylated gelatin in a ratio of about 3:1, about 7:2, about 4:1, about 5:1, about 10:1, about 15:1, about 20:1, or about 25:1 (w / w). In some embodiments, the scaffold is fabricated from a mixture comprising poly(ethylene glycol) diacrylate and methacrylated gelatin in a ratio of about 25:1 to about 3:1, about 20:1 to about 7:2, about 15:1 to about 4:1, or about 10:1 to about 4:1 (w / w). In some embodiments, the scaffold comprises poly(ethylene glycol) diacrylate and methacrylated gelatin in a ratio of about 3:1, about 7:2, about 4:1, about 5:1, about 10:1, about 15:1, about 20:1, or about 25:1 (w / w). In some embodiments, the scaffold comprises poly(ethylene glycol) diacrylate and methacrylated gelatin in a ratio of about 25:1 to about 3:1, about 20:1 to about 7:2, about 15:1 to about 4:1, or about 10:1 to about 4:1 (w / w).

[0031] In some embodiments, the scaffold is fabricated from a mixture comprising poly(ethylene glycol) diacrylate and methacrylated collagen. In some embodiments, the scaffold is fabricated from about 25% poly(ethylene glycol) diacrylate (average size Mn 700) and about 2-10 mg / ml methacrylated collagen. In some embodiments, the scaffold is fabricated from a mixture comprising about 15%, about 17.5%, about 20%, about 22.5%, about 25%, about 27.5%, about 30%, about 32.5%, or about 35% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is fabricated from a mixture comprising about 22.5% to about 27.5%, about 20% to about 30%, about 17.5% to about 32.5%, or about 15% to about 35% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is fabricated from a mixture comprising about 25% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is fabricated from a mixture comprising about 20% to about 30% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is fabricated from a mixture comprising about 15% to about 30% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is fabricated from a mixture comprising about 20% to about 25% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is fabricated from a mixture comprising about 15% to about 25% poly(ethylene glycol) diacrylate. In some embodiments, the scaffold is fabricated from a mixture comprising about 20% to about 30% poly(ethylene glycol) diacrylate. In some embodiments, the average molecular weight of the poly(ethylene glycol) diacrylate is about Mn 550, about Mn 700, about Mn 1000, about Mn 2000, or about Mn 4000. In some embodiments, the average molecular weight of the poly(ethylene glycol) diacrylate is about Mn 500 to about Mn 1000. In some embodiments, the average molecular weight of the poly(ethylene glycol) diacrylate is about Mn 700. In some embodiments, the average size of the poly(ethylene glycol) diacrylate is about 100 Mn to 1000 Mn.In some embodiments, the scaffold is fabricated from a mixture comprising about 2-10 mg / ml, about 3-9 mg / ml, or about 4-8 mg / ml of methacrylated collagen. In some embodiments, the scaffold is fabricated from a mixture comprising about 1-15 mg / ml of methacrylated collagen. In some embodiments, the scaffold is fabricated from a mixture comprising poly(ethylene glycol) diacrylate and methacrylated collagen in a ratio of about 125:1 to about 25:1, about 100:1 to about 40:1, or about 75:1 to about 50:1 (w / w). In some embodiments, the scaffold is fabricated from a mixture comprising poly(ethylene glycol) diacrylate and methacrylated collagen in a ratio of about 125:1, about 100:1, about 75:1, about 50:1, about 40:1, or about 25:1 (w / w). In some embodiments, the scaffold comprises poly(ethylene glycol) diacrylate and methacrylated collagen in a ratio of about 125:1 to about 25:1, about 100:1 to about 40:1, about 75:1 to about 50:1 (w / w). In some embodiments, the scaffold comprises poly(ethylene glycol) diacrylate and methacrylated collagen in a ratio of about 125:1, about 100:1, about 75:1, about 50:1, about 40:1, or about 25:1 (w / w).

[0032] In certain embodiments, the microchannels can be treated with biofunctional agents or active ingredients, have different surface properties or surface roughness, or have different exposed surfaces, which is useful for designing spatially guided cell growth and, in certain embodiments, for promoting cell or tissue adhesion or for promoting the release of biofunctional agents, including biofunctional materials and active ingredients (e.g., active pharmaceutical ingredients), into the surrounding environment.

[0033] Biodegradable materials forming microchannels can dissolve (referring to the physical breakdown, erosion, destruction, and / or dissolution of the material), which can include resorption of such materials by living organisms. In certain variations, biodegradable polymeric materials can be dissolved or eroded by exposure to solvents containing high concentrations of water, such as blood, serum, growth or culture medium, bodily fluids, saliva, etc. Thus, upon implantation, the material can dissolve or disintegrate into small pieces. As a structural scaffold member, the dissolution rate (e.g., the rate at which the structural member is resorbed by surrounding cells) can be designed to allow sufficient cell proliferation before the structure dissolves or disintegrates through the resorption process. In various embodiments, tissue scaffold devices are designed so that the degradation time or dissolution rate corresponds to the amount of time that allows appropriate neural tissue regrowth through the scaffold and into the target tissue of the subject. Depending on the subject and the time required for tissue recovery and regeneration, by way of non-limiting example, the degradation time can be from about 1 month to about 3 years, from about 1 month to 1 year, and in certain variations, from about 1 month to 6 months. In this way, the cell scaffold structure supports and promotes cell growth, cell proliferation, cell differentiation, cell repair, and / or cell regeneration in three dimensions, particularly for neural tissue growth.

[0034] In certain aspects, the walls of the microchannels are porous. The pore size can be selected to promote substantially linear neural or axonal tissue growth along the longitudinal axis while avoiding cell growth across the microchannel walls. In some embodiments, the microchannels are made of hydrogels, such as a mixture of poly(ethylene glycol) diacrylate and methacrylated gelatin, or a mixture of poly(ethylene glycol) diacrylate and methacrylated collagen. Due to the properties of the microchannels containing the hydrogels provided herein, nutrients can be exchanged between the exterior of the scaffold and the interior of the microchannel without the use of pores. The natural porosity of these materials allows the flow of nutrients and oxygen through the microchannel walls to support cells growing through the lumen while preventing cell growth in undesired directions (e.g., through the microchannel walls).

[0035] The microchannel walls optionally comprise a plurality of pores having an average pore size of about 50 μm or less in diameter, optionally about 40 μm or less, optionally about 30 μm or less, optionally about 20 μm or less, and in certain variations, optionally about 10 μm or less. In certain embodiments, the plurality of pores in the microchannel walls have an average pore size that eliminates connecting pathways between the pores that would allow axons to grow between the respective microchannels. Such pore sizes facilitate the flow of oxygen and nutrients from the exterior to the interior surface through the microchannel walls, supporting cells growing within the open central lumen while minimizing or preventing cells from growing through the microchannel walls.

[0036] In another aspect, the present disclosure provides a method for producing a biomimetic scaffold for promoting neural tissue growth by 3D printing. The scaffolds provided herein can be fabricated using various 3D printing techniques. Examples of 3D printing techniques that can be used to prepare 3D printed scaffolds include extrusion printing, inkjet printing, laser-based stereolithography, digital light processing stereolithography, and volumetric 3D printing (also known as holographic 3D printing). In some embodiments, the biomimetic scaffolds provided herein are fabricated by digital light processing 3D printing. Additional methods for 3D printing of biomimetic scaffolds are described in PCT / US2017 / 0655857, which is incorporated herein by reference in its entirety.

[0037] In other aspects, the biomimetic scaffolds provided herein can be made from other techniques, including casting, molding, electrospinning, embossing, or any other suitable method. Exemplary alternative methods for manufacturing biomimetic scaffolds are described, for example, in PCT / US2016 / 056104 and PCT / US2020 / 012966, each of which is incorporated by reference in its entirety.

[0038] The disclosed microchannel scaffolds disclosed herein promote cell growth, proliferation, differentiation, repair, and / or regeneration of tissue. In certain embodiments, the tissue is neural tissue, such as axons.

[0039] In certain embodiments, a suitable wall thickness for a microchannel wall is the minimum thickness that maintains structural integrity for the channel. In certain aspects, the wall thickness is about 500 μm or less. In other aspects, the wall thickness is about 100 μm or less. Wall thicknesses greater than 100 μm may reduce the amount of space available for axonal regeneration within the open central lumen. In certain variations, the wall thickness may be about 10 μm or more to about 100 μm or less, optionally about 10 μm or more to about 70 μm or less, optionally about 20 μm or more to about 70 μm or less, optionally about 25 μm or more to about 67 μm or less, and in certain aspects, optionally about 20 μm or more to about 50 μm or less. In certain other variations, the wall thickness is about 10 μm or more to about 20 μm or less.

[0040] One particular advantage of tissue scaffold designs according to various embodiments of the present disclosure is that they provide a total volume (e.g., open lumen volume, including the volume of open interstitial channels within the sheath and the open central lumen of the microchannels) of about 50% by volume or more, optionally about 60% by volume or more, optionally about 70% by volume or more, optionally about 80% by volume or more, and in certain preferred embodiments, optionally about 90% by volume or more of the total scaffold volume. It is noted that prior scaffold designs have been unable to achieve such high levels of open lumen volume, which are believed to be particularly advantageous for supporting and promoting the growth of healthy neural tissue with desirable high directional linearity and high signal fidelity.

[0041] In certain embodiments, the diameter of each microchannel of a plurality of microchannels disposed within the sheath is selected to be the same (or substantially the same, taking into account minor dimensional variations during manufacturing), although in alternative variations, the diameter may be intentionally varied among multiple individual microchannels present within the sheath. As noted above, in variations in which multiple microchannels have substantially the same diameter, the average inner diameter is optionally about 450 μm or less or any of the other ranges defined above. Each microchannel may have an elliptical or spherical cross-sectional shape, forming a microcylinder shape that creates significant open interstitial volume within the interstitial channel, although other shapes may be used in other variations. When multiple microchannels have substantially the same diameter, they may be configured to be arranged in a close-packed arrangement within the sheath. Thus, each microchannel contacts another adjacent microchannel. Multiple microchannels may be arranged in a close-packed arrangement that can create a honeycomb-type arrangement within the sheath. In this manner, the tissue scaffold of the present disclosure comprises a discrete, linear, thin-walled, close-packed array of microchannels arranged within an outer protective sheath. The density of the microchannels can vary in different embodiments, for example, the density of the microchannels can range from about 1 to about 300 microchannels / mm in the scaffold. 2 In certain variations, the microchannel density can be between about 10 and about 30 microchannels / mm 2 In another variation, the microchannel density of the tissue scaffold can be about 120 microchannels / mm 2 In some variations, the microchannel density of the tissue scaffold can be from about 10 microchannels to about 300 microchannels / mm 2In some variations, the microchannel density can be from about 10 to about 20, from about 10 to about 30, from about 10 to about 50, from about 10 to about 100, from about 10 to about 120, from about 10 to about 150, from about 10 to about 200, from about 10 to about 300, from about 20 to about 30, from about 20 to about 50, from about 20 to about 100, from about 20 to about 120, from about 20 to about 150, from about 20 to about 200, from about 20 to about 300, from about 30 to about 50, from about 30 to about 100, from about 30 to about 120, from about 30 to about 150, about 30 to about 200, about 30 to about 300, about 50 to about 100, about 50 to about 120, about 50 to about 150, about 50 to about 200, about 50 to about 300, about 100 to about 120, about 100 to about 150, about 100 to about 200, about 100 to about 300, about 120 to about 150, about 120 to about 200, about 120 to about 300, about 150 to about 200, about 150 to about 300, or about 200 to about 300 microchannels / mm 2 In some variations, the microchannel density is about 10, about 20, about 30, about 50, about 100, about 120, about 150, about 200, or about 300 microchannels / mm 2 In some variations, the microchannel density is at least about 10, about 20, about 30, about 50, about 100, about 120, about 150, or about 200 microchannels / mm 2 In some variations, the microchannel density is at most about 20, about 30, about 50, about 100, about 120, about 150, about 200, or about 300 microchannels / mm 2In some embodiments, the number of microchannels in a single sheath can be from 7 to over 200 channels. In some variations, the number of microchannels in a single sheath is from about 7 to about 200 channels. In some variations, the number of microchannels in a single sheath is from about 7 to about 15, from about 7 to about 25, from about 7 to about 50, from about 7 to about 75, from about 7 to about 100, from about 7 to about 150, from about 7 to about 200, from about 15 to about 25, from about 15 to about 50, from about 15 to about 75, from about 15 to about 100, from about 15 to about 150, from about 15 to about 200, from about 25 to about 5 0, about 25 to about 75, about 25 to about 100, about 25 to about 150, about 25 to about 200, about 50 to about 75, about 50 to about 100, about 50 to about 150, about 50 to about 200, about 75 to about 100, about 75 to about 150, about 75 to about 200, about 100 to about 150, about 100 to about 200, or about 150 to about 200 channels. In some variations, the number of microchannels in a single sheath is from about 7, about 15, about 25, about 50, about 75, about 100, about 150, or about 200 channels. In some variations, the number of microchannels in a single sheath is from at least about 7, about 15, about 25, about 50, about 75, about 100, or about 150 channels. In some variations, the number of microchannels in a single sheath is from about 15, about 25, about 50, about 75, about 100, about 150, or about 200 channels, In some embodiments, the number of microchannels in a single sheath is from about 300, 400, 500, 750, or 1000 channels.

[0042] The sheath can be formed of a biocompatible and / or biodegradable material, which can be the same or different from the microchannels. Desirably, the sheath has similar porosity to the microchannels, minimizing or preventing cell proliferation from the interior region through the sheath wall to the exterior region while promoting nutrient flow and transport to the microchannels. While the sheath is shown as a cylindrical tube with an elliptical or cylindrical cross-sectional shape, the sheath can have a variety of other shapes, as long as the microcylinders can be arranged side-by-side within the sheath. Thus, in certain embodiments, the sheath can have other shapes, including, by way of non-limiting example, a butterfly shape similar to that found in the human spine. The sheath can have the same length as the microcylinders, or it can be longer, such as with protrusions for additional protection and fixation to portions of the nerve or surrounding tissue (e.g., by anastomosis). In this way, the tissue scaffold, including the sheath and microchannels, can extend over any distance to accommodate the injury of an individual subject / patient. Furthermore, the actual shape or geometry of the entire scaffold can be fabricated to match the exact shape or geometry of the given injury (this shape can be determined by traditional medical imaging methods such as MRI, CT, ultrasound, etc.).

[0043] The scaffold may be filled with cells, which may be modified to express growth factors or may be therapeutic in nature, such as stem cells or Schwann cells.

[0044] A portion of a target nerve, such as a nerve end, can be damaged or severed, e.g., a completely or partially damaged nerve end caused by injury, disease, or surgery. In certain embodiments, a portion of the nerve end can be surgically divided, sectioned, cut, and / or transected into one or more individual branches or bundles, which can be secured to the proximal or distal end of a tissue scaffold. One or more individual branches or bundles of the nerve end can contact or be positioned within one or more microchannels. The nerve end (or its individual branches or bundles) can be secured to the proximal or distal end of a sheath via sutures, adhesives, or other known fixation techniques. For example, over a period of several months, neural tissue derived from the nerve end can grow along the longitudinal axis of each microchannel and reinnervate any neural targets at the opposite end of the tissue scaffold. Thus, tissue scaffolds according to various embodiments of the present teachings promote the growth of neural tissue through the open central lumen of the multiple microchannels from a first end of the scaffold to a second, opposite end.

[0045] As will be appreciated by those skilled in the art, the structure of the tissue scaffold of the present invention is particularly suited to promoting neural tissue growth, although in further variations the tissue scaffold can be used for other types of tissue growth.

[0046] In other embodiments, the wall surfaces of the microchannels can be coated with a biofunctional agent, for example, to promote cell growth, regeneration, differentiation, proliferation, and / or repair. "Promoting" cell growth, cell proliferation, cell differentiation, cell repair, or cell regeneration means that a detectable increase in the rate of a series of changes or a measurable effect occurs in the presence of the biofunctional agent compared to the cell or organism's natural progression in the absence of the biofunctional agent, e.g., the natural progression of such changes. By way of example, as will be understood by those skilled in the art, promoting cell growth in the presence of a biofunctional agent can increase the growth rate of target cells or increase the total cell number of target cells when compared to the cell growth or cell number of target cells in the absence of the biofunctional agent.

[0047] As used herein, "biofunctional agent" refers to a molecule that promotes cell growth, cell adhesion, cell proliferation, cell differentiation, cell repair, and / or cell regeneration by increasing a measurable effect (e.g., measuring the total cell number of cell development or cell regeneration, measuring the rate or qualitative effect of cell proliferation, cell differentiation, or cell repair rate). In some embodiments, the biofunctional agents disclosed herein promote the regenerative process by about 25% or more, optionally by an increase of about 30% or more, optionally by an increase of about 35% or more, optionally by an increase of about 40% or more, optionally by an increase of about 45% or more, optionally by an increase of about 50% or more, optionally by an increase of about 55% or more, optionally by an increase of about 60% or more, optionally by an increase of about 65% or more, optionally by an increase of about 70% or more, optionally by an increase of about 75% or more, optionally by an increase of about 80% or more, optionally by an increase of about 85% or more, optionally by an increase of about 90% or more, and in certain aspects, optionally by an increase of about 95% or more, compared to the results of the process in the absence of the biofunctional agent.

[0048] Exemplary biofunctional agents include, but are not limited to, fibronectin, keratin, laminin, collagen, growth factors, and / or stem cell promoting factors. Exemplary growth factors include brain-derived neurotrophic factor (BDNF), nerve growth factor, glial cell line-derived neurotrophic factor (GDNF), and neurotrophin-3 (NT-3). In some embodiments, the growth factor is BDNF. In some embodiments, the growth factor is nerve growth factor. In some embodiments, the growth factor is GDNF. In some embodiments, the growth factor is NT-3.

[0049] Such biofunctional agents can be introduced after the microchannels are formed, for example, by coating, injecting, or otherwise incorporating the biofunctional agent onto one or more surfaces (e.g., inner surfaces) of the microchannel walls. In certain aspects, the porous wall surfaces have a coating comprising a material for promoting neural tissue growth selected from the group consisting of fibronectin, keratin, laminin, collagen, and combinations and equivalents thereof. In certain embodiments, the walls can be coated with fibronectin, and after screening many compounds, fibronectin was found to be particularly advantageous for optimizing cell and axonal attachment in conjunction with the biocompatible polymers that form the microchannel walls.

[0050] This technology therefore represents a significant advance over existing techniques for surgical repair of injured peripheral nerves. These conventional devices consist of only a single open channel (not divided into individual microchannels), which frequently deviates axons from their linear path, reducing the number of axons that reach the distal end of the scaffold and contribute to nerve repair. More commonly, such simpler structures, which are commercially available, result in painful neuromas and a lack of functional improvement due to axon misguidance. Additionally, the properties of the materials that make up conventional scaffolds do not adequately support cell and axon attachment. Based on empirical observations after implanting and testing hydrogel nerve regeneration scaffolds, hydrogel-based materials do not exhibit sufficient strength to allow the fabrication of thin-walled (<50 μm) scaffolds. However, based on calculations, a wall thickness of less than 50 microns appears necessary to obtain a scaffold with a >80% luminal volume that adequately supports and promotes neural tissue growth. Thus, currently available hydrogel-based materials fail to provide scaffolds with adequate strength and the advantageous open lumen volume provided by certain aspects of the present teachings. Conversely, materials provided herein, such as hydrogels comprising a mixture of poly(ethylene glycol) methacrylate and methacrylated gelatin or a mixture of poly(ethylene glycol) methacrylate and methacrylated collagen, are mechanically designed to be stable in vivo. In some embodiments, the use of 3D printing (e.g., digital light processing or other suitable methods) allows for high resolution in printing microchannel walls. This high resolution, in some embodiments, allows for scaffolds using the materials provided herein to have the strength required for in vivo stability. In some embodiments, high-resolution 3D printing allows for the construction of scaffolds with wall thicknesses as thin as 10 microns.

[0051] The present tissue scaffold device excels in providing a multi-lumen structure that enhances nerve guidance, thereby increasing the total number of axons that regenerate normally. As a result, such tissue scaffold devices function across long nerve gaps and in more proximal nerve injuries, thereby addressing a significant unmet medical need. Furthermore, tissue scaffolds according to the present disclosure are made from biocompatible and biodegradable materials, such as poly(ethylene glycol) diacrylate, methacrylated gelatin, methacrylated collagen, polycaprolactone, or acrylated polycaprolactone, and have optimized porosity and surface roughness, providing excellent cell adhesion and directional cell growth while exhibiting significantly reduced inflammatory responses in vivo after implantation. When tested in vivo, the devices of the present disclosure are biocompatible.

[0052] In this manner, tissue scaffold devices according to certain embodiments of the present disclosure may enable one or more of the following unique features or advantages: a close-packed array of linear microchannels that mimics natural nerve tissue; microchannels with meaningful, customizable lengths; hexagonal microchannels to maximize the number of channels within the sheath; thin-walled microchannels to maximize open volume; high open lumen volume; scaffold devices comprising biocompatible materials; the ability to control mechanical properties to optimize strength and suturability as the outer sheath tube minimizes wall thickness; the ability to control the porosity of the scaffold and sheath to prevent axonal permeation while allowing permeation of oxygen and other nutrients; the ability to modify the surface properties of the microchannels to allow cell adhesion; a one-piece sheath and scaffold structure that facilitates ease of implantation allowing secure attachment between the nerve stump and the scaffold wall; and ultimately low material and manufacturing costs.

[0053] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

[0054] Example Example 1. Multi-channel scaffold for nerve injury repair in a rat model In some embodiments, the device is fabricated from porous PCL and contains linear microchannels. The entire device has an inner diameter of 1.6 mm, a length of 10 mm, and 1 mm protrusions on each side from the outer sheath (e.g., for suturing into place in the subject). To evaluate the effectiveness of these devices for nerve repair, the devices are tested in a rat sciatic nerve model. An image of an intact rat sciatic nerve is shown in Figure 12. Animals are housed (e.g., 2-3 per cage) with free access to food and water in a facility approved by the American Association for the Accreditation of Laboratory Animal Care. All animal studies are conducted in accordance with NIH guidelines for the care and safety of laboratory animals, implementing protocols approved by the Institutional Animal Care and Use Committee of the VA Healthcare System in San Diego.

[0055] To implant the device (n=6), animals were deeply anesthetized (e.g., using ketamine (25 mg / mL), xylazine (1300 mg / mL), and acepromazine (0.25 mg / mL)) before making a 20 mm incision in the right thigh. The right sciatic nerve trunk was exposed through a lateral gluteal incision. The epineurial connective tissue around the nerve trunk was separated with ultra-fine scissors, and a 6.0 mm long nerve fragment was excised. After tissue retraction, the cut nerve stumps were further separated by approximately 15 mm and protected and hydrated with saline. The device was positioned and attached to the nerve at both ends using 9-0 Ethicon sutures. The device was positioned to avoid stretching at the interface between the device and the nerve site. Following implantation, the muscle was sutured with 5-0 sutures, and the skin was closed with clips. Antibiotics and analgesics (e.g., basil (1 mg / kg) and ampicillin (0.2 mg / kg) in Ringer's lactate) are administered for the first 3 days to facilitate recovery from surgery. After 4 weeks, the instruments are removed. The animals are perfused with 4% paraformaldehyde (PFA), and the tissues are removed and post-fixed for an additional 24 h in PFA, followed by 48 h in 30% sucrose.

[0056] After 4 weeks, observations are expected to show no signs of device degradation. To assess nerve regeneration across the injury site, immunolabeling will be performed on histological sections. Tissues will be processed for 1) axonal labeling, e.g., to assess axonal regeneration through the injury site (NF200), and 2) Schwann cell (S100) labeling.

[0057] The microchannels of the device induce aligned neurite growth throughout the entire length of the scaffold, with nerves exiting the distal side of the implant. Unlike more traditional fabrication methods (e.g., dip coating), the high open lumen volume of the devices provided herein allows more neurons to regenerate due to reduced volume absorbed by the pore walls. Thus, this technology provides faster healing of nerve injuries with better functional recovery.

[0058] Example 2. Multi-channel scaffold for nerve injury repair in a rat model Multichannel scaffolds fabricated using the embossing method were implanted into 1-cm-long defects in rat sciatic nerves and compared with sural nerve autografts or open-tube implants. The scaffolds used in this study contained eight microchannels, each approximately 200 microns in diameter. The scaffolds were 1 cm long and had an outer diameter of 1.7 mm. Example images of scaffolds implanted in rats are shown in Figure 13. Four weeks after implantation, the multichannel scaffolds supported linear alignment and accelerated regeneration of axons across the injury site. Six months after implantation, the multichannel scaffolds demonstrated improved connectivity between the spinal cord and gastrocnemius muscle compared to open-tube treatment and comparable to autografts. Furthermore, the multichannel scaffolds doubled the muscle mass gain compared to injury alone or open-tube treatment and supported muscle mass gain comparable to autografts. The multichannel scaffold, shown in Figure 9B, demonstrates superior axon alignment and faster regeneration rates across a 1 cm sciatic nerve gap in rats (shown 4 weeks after injury) compared to open-tube scaffolds at the same time point (Figure 9A). Figure 10 shows improved connectivity between spinal motor neurons and muscle, assessed by injecting a retrograde tracer (cholera toxin B) into the gastrocnemius muscle 6 months after nerve repair. Figure 11 demonstrates significantly improved muscle mass. Statistically, the multichannel scaffold is as effective as a sural nerve autograft. N = 11 animals per group.

[0059] The biomimetic scaffold with hexagonal microchannels disclosed herein improves anatomical and electrophysiological connectivity across the sciatic nerve injury site, supporting recovery of motor function.

[0060] Unless otherwise noted, all numbers used in the specification and claims expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and the like, should be understood to be modified in all instances by the term "about." As used herein, the terms "about" and "approximately" mean within 10 to 15%, preferably within 5 to 10%. Accordingly, unless expressly indicated to the contrary, the numerical parameters set forth in the specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0061] As used in the context of describing the present invention (particularly in the claims that follow), the terms "a," "an," "the," and similar referents should be construed to include both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of individually referring to each individual value falling within the range. Unless otherwise stated herein, each of the values ​​individually is incorporated herein as if individually set forth herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples or exemplary language (e.g., "etc.") provided herein is intended merely to further clarify the invention and does not otherwise limit the scope of the claimed invention. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0062] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limiting. Each of the group elements may be referenced and claimed individually or in any combination with other elements of the group or other elements found herein. It is anticipated that one or more elements of a group may be included in, or deleted from, a group for reasons of convenience and / or patentability. When such inclusion or deletion occurs, the specification is deemed to include the modified group, and thus fulfills the written description of all Markush groups used in the appended claims.

[0063] Certain embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations on these described embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors expect skilled artisans to adopt such variations as they see fit, and the inventors intend the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is included in the invention unless otherwise indicated herein or clearly contradicted by context.

[0064] Certain embodiments disclosed herein may be further limited in the claims using the words "consisting of" or "consisting essentially of." When used in a claim, whether submitted per amendment or added, the transition term "consisting of" excludes any element, step, or ingredient not specified in the claim. The transition term "consisting essentially of" limits the claim to certain materials or steps and those that do not materially affect the basic and novel characteristics. Embodiments of the invention so claimed are essentially or expressly described and enabled herein.

[0065] Additionally, throughout this specification, various references have been made to patents and printed publications. Each of the above-cited references and printed publications is individually incorporated herein by reference in its entirety.

[0066] When a component, element, or layer is referred to as being "on," "engaged to," "connected to," or "coupled to" another element or layer, it may be directly on, engaged with, connected to, or connected to the other component, element, or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on," "directly engaged," "directly connected," or "directly coupled to" another element or layer, there may be no intervening elements or layers. Other words used to describe relationships between elements should be interpreted in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0067] Terms such as "first," "second," and "third" may be used herein to describe various steps, elements, components, regions, layers, and / or sections; however, these steps, elements, components, regions, layers, and / or sections should not be limited by these terms unless otherwise specified. These terms may be used only to distinguish one step, element, component, region, layer, or section from another step, element, component, region, layer, or section. When used herein, terms such as "first," "second," and other numerical terms do not imply sequential numbering or ordering unless clearly indicated by context. Thus, a first step, element, component, region, layer, or section discussed below could be referred to as a second step, element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0068] Spatial or temporal relative terms such as "front," "rear," "inside," "outside," "beneath," "below," "lower," "above," "upper," etc. may be used herein for ease of description to describe the relationship of one element or feature to another, as shown in the figures. Spatial or temporal relative terms may be intended to encompass different orientations of the device or system in use or operation in addition to the orientation shown in the figures.

[0069] Throughout this disclosure, numerical values ​​represent approximate measures or limits of ranges encompassing slight deviations from the given value, as well as embodiments with approximate and exact values. Except for the examples provided at the end of the detailed description, all numerical values ​​of parameters (e.g., amounts or conditions) in this specification, including the appended claims, should be understood in all cases to be modified by the term "about," whether or not "about" actually precedes the numerical value. "About" (with some approximation to the precision of the value, approximately, or very close to the value, approximately) indicates that the stated numerical value allows for some slight imprecision. Unless the imprecision introduced by "about" is otherwise understood in the art from its ordinary meaning, "about," as used herein, at least indicates the variation that can result from ordinary methods of measuring and using such parameters. For example, "about" can include variations of 5% or less, optionally 4% or less, optionally 3% or less, optionally 2% or less, optionally 1% or less, optionally 0.5% or less, and in certain embodiments, optionally 0.1% or less.

[0070] Furthermore, disclosure of a range includes disclosure of all values ​​and further divided ranges within the entire range, including the endpoints and sub-ranges given in the range.

[0071] Finally, it is to be understood that the embodiments of the invention disclosed herein are illustrative of the principles of the invention. Other modifications that may be employed are within the scope of the invention. Thus, by way of example, but not of limitation, alternative configurations of the invention may be utilized in accordance with the teachings herein. Consequently, the invention is not limited to that precisely as shown and described.

[0072] Numbered Embodiments The following embodiments list non-limiting permutations of feature combinations disclosed herein. Other permutations of feature combinations are also contemplated. Specifically, each of these numbered embodiments is intended to be dependent on or related to any preceding or following numbered embodiment, regardless of their listed order.

[0073] Embodiment 1. A nerve repair scaffold comprising: a sheath having a proximal end and a distal end and containing a plurality of microchannels traversing from the proximal end to the distal end, the microchannels being configured to allow neural tissue growth; and a first protrusion at the proximal end and a second protrusion at the distal end configured to suture neural tissue.

[0074] Embodiment 2. The nerve repair scaffold of embodiment 1, wherein the shape of the microchannels is hexagonal, round, triangular, rectangular, square, pentagonal, heptagonal, octagonal, nonagonal, decagonal, elliptical, or trapezoidal.

[0075] Embodiment 3. The nerve repair scaffold of embodiment 2, wherein the microchannels are hexagonal in shape.

[0076] Embodiment 4. The nerve repair scaffold of embodiment 2, wherein the microchannels are round in shape.

[0077] Embodiment 5. The nerve repair scaffold of any one of embodiments 1-4, wherein the scaffold comprises from about 7 to about 200 of the microchannels.

[0078] Embodiment 6. The nerve repair scaffold of embodiment 5, wherein the scaffold comprises 5-15 of the microchannels.

[0079] Embodiment 7. The density of the microchannels is from about 10 to about 300 microchannels / mm 2 7. The nerve repair scaffold of any one of embodiments 1-6, wherein

[0080] Embodiment 8. The nerve repair scaffold of any one of embodiments 1-7, wherein the length of the scaffold is from about 0.5 cm to about 15 cm.

[0081] Embodiment 9. A nerve repair scaffold according to any one of embodiments 1-8, wherein the outer diameter is from about 1.5 mm to about 10 mm.

[0082] Embodiment 10. A nerve repair scaffold described in any one of embodiments 1-9, wherein the inner diameter of each of the microchannels is from about 150 μm to about 250 μm.

[0083] Embodiment 11. A nerve repair scaffold described in any one of embodiments 1-10, wherein the wall thickness of each of the microchannels is from about 10 μm to about 60 μm.

[0084] Embodiment 12. A nerve repair scaffold according to any one of embodiments 1-11, wherein each of the microchannels is the same size.

[0085] Embodiment 13. A nerve repair scaffold according to any one of embodiments 1-12, wherein the scaffold comprises microchannels of different sizes.

[0086] Embodiment 14. The nerve repair scaffold of any one of embodiments 1-13, wherein the first and second protrusions have lengths independently of each other of about 0.1 mm to about 3 mm.

[0087] Embodiment 15. The nerve repair scaffold of any one of embodiments 1-14, wherein the thickness of the first and second protrusions is independently about 0.1 mm to about 3 mm.

[0088] Embodiment 16. The nerve repair scaffold of any one of embodiments 1-15, wherein the scaffold is formed from a biocompatible material selected from poly(ethylene glycol) diacrylate, methacrylated gelatin, methacrylated collagen, polycaprolactone, and acrylated polycaprolactone, or any combination thereof.

[0089] Embodiment 17. The nerve repair scaffold of embodiment 16, wherein the average molecular weight of the poly(ethylene glycol) diacrylate is from about Mn 500 to about Mn 1000.

[0090] Embodiment 18. The nerve repair scaffold of embodiment 17, wherein the poly(ethylene glycol) diacrylate has an average molecular weight of about Mn 700.

[0091] Embodiment 19. The nerve repair scaffold of any one of embodiments 16-18, wherein the scaffold is formed from a mixture comprising poly(ethylene glycol) diacrylate and methacrylated gelatin.

[0092] Embodiment 20. The nerve repair scaffold of embodiment 19, wherein the scaffold is made from about 25% poly(ethylene glycol) diacrylate and about 1-7% methacrylated gelatin.

[0093] Embodiment 21. The nerve repair scaffold of embodiment 19, wherein the ratio of poly(ethylene glycol) diacrylate to methacrylated gelatin in the scaffold is from about 25:1 to about 3:1.

[0094] Embodiment 22. A nerve repair scaffold according to any one of embodiments 16-18, wherein the scaffold is formed from a mixture comprising poly(ethylene glycol) diacrylate and methacrylated collagen.

[0095] Embodiment 23. The nerve repair scaffold of embodiment 22, wherein the scaffold is made from about 25% poly(ethylene glycol) diacrylate and about 2-10 mg / ml methacrylated gelatin.

[0096] Embodiment 24. The nerve repair scaffold of embodiment 22, wherein the ratio of poly(ethylene glycol) diacrylate to methacrylated gelatin in the scaffold is from about 125:1 to about 25:1 (w / w).

[0097] Embodiment 25. The nerve repair scaffold of any one of embodiments 1-24, wherein the scaffold further comprises a biofunctional agent.

[0098] Embodiment 26. The nerve repair scaffold of embodiment 25, wherein the biofunctional agent is coated on or incorporated into the walls of the microchannels.

[0099] Embodiment 27. The nerve repair scaffold of embodiment 25 or 26, wherein the biofunctional agent comprises fibronectin, collagen, laminin, keratin, a growth factor, or a stem cell promoting factor.

[0100] Embodiment 28. The nerve repair scaffold of embodiment 27, wherein the growth factor is brain-derived neurotrophic factor, nerve growth factor, glial cell line-derived neurotrophic factor, or neurotrophin-3.

[0101] Embodiment 29. The nerve repair scaffold of any one of embodiments 1-28, wherein the scaffold is further filled with cells.

[0102] Embodiment 30. The nerve repair scaffold of embodiment 29, wherein the cells are stem cells or Schwann cells.

[0103] Embodiment 31. A nerve repair scaffold according to any one of embodiments 1-30, wherein the scaffold comprises an open volume of about 70% or more.

[0104] Embodiment 32. A nerve repair scaffold according to any one of embodiments 1-31, wherein the scaffold is 3D printed.

[0105] Embodiment 33. A nerve repair scaffold comprising: a sheath having a proximal end and a distal end and containing a plurality of microchannels traversing from said proximal end to said distal end, said microchannels configured to allow neural tissue to grow therethrough, at least one of the walls of said microchannels comprising a biofunctional agent incorporated into the wall of said microchannel.

[0106] Embodiment 34. The nerve repair scaffold of embodiment 33, wherein said biofunctional agent promotes cell growth, regeneration, differentiation, proliferation, repair, or any combination thereof.

[0107] Embodiment 35. The nerve repair scaffold of embodiment 33 or 34, wherein the biofunctional agent comprises fibronectin, keratin, laminin, collagen, a growth factor, or a stem cell promoting factor.

[0108] Embodiment 36. The nerve repair scaffold of any one of embodiments 33-35, wherein the growth factor is brain-derived neurotrophic factor, nerve growth factor, glial cell line-derived neurotrophic factor, or neurotrophin-3, or any combination thereof.

[0109] Embodiment 37. A nerve repair scaffold described in any one of embodiments 33-36, further comprising a first protrusion at the proximal end and a second protrusion at the distal end, wherein the first protrusion and the second protrusion are configured for suturing nerve tissue.

[0110] Embodiment 38. A nerve repair scaffold according to any one of embodiments 33-37, wherein the scaffold is further filled with cells.

[0111] Embodiment 39. A nerve repair scaffold described in any one of embodiments 33-38, wherein the open diameter of each of the microchannels is from about 200 μm to about 500 μm.

[0112] Embodiment 40. The density of the microchannels is from about 10 to about 30 microchannels / mm 2 40. The nerve repair scaffold of any one of embodiments 33-39, wherein

[0113] Embodiment 41. A nerve repair scaffold according to any one of embodiments 33-40, wherein the scaffold is made from about 20-30% poly(ethylene glycol) diacrylate and about 1-7% methacrylated gelatin.

[0114] Embodiment 42. The nerve repair scaffold of any one of embodiments 33-41, wherein the ratio of poly(ethylene glycol) diacrylate to methacrylated gelatin in the scaffold is from about 25:1 to about 3:1.

[0115] Embodiment 43. The nerve repair scaffold of any one of embodiments 33-40, wherein the scaffold is made from about 25% poly(ethylene glycol) diacrylate and about 2-10 mg / mL of methacrylated collagen.

[0116] Embodiment 44. The nerve repair scaffold of any one of embodiments 33-40 or 43, wherein the ratio of poly(ethylene glycol) diacrylate to methacrylated collagen in the scaffold is from about 125:1 to about 25:1.

[0117] Embodiment 45. A nerve repair scaffold described in any one of embodiments 33-44, wherein the plurality of microchannels comprises from about 7 to about 200 microchannels.

[0118] Embodiment 46. A nerve repair scaffold described in any one of embodiments 33-45, wherein the wall thickness of the microchannel is from about 10 μm to about 60 μm.

[0119] Embodiment 47. A nerve repair scaffold described in any one of embodiments 33-46, wherein the length of the scaffold is 0.5 mm to 15 cm.

[0120] Embodiment 48. A nerve repair scaffold described in any one of embodiments 33-47, wherein the length of the scaffold is 5 cm to 10 cm.

[0121] Embodiment 49. A nerve repair scaffold according to any one of embodiments 33-48, wherein the scaffold comprises an open volume of about 70% or more.

[0122] Embodiment 50. A nerve repair scaffold described in any one of embodiments 33-49, wherein the scaffold is 3D printed.

[0123] Embodiment 51. A nerve repair scaffold comprising: a sheath having a proximal end and a distal end, the sheath containing a plurality of microchannels traversing from the proximal end to the distal end, the microchannels configured to allow neural tissue to grow through the sheath; and a first protrusion at the proximal end and a second protrusion at the distal end configured to suture neural tissue, the scaffold further comprising a biofunctional agent, wherein the open diameter of each of the microchannels is from about 200 μm to about 350 μm, and wherein the scaffold is made from about 15% to about 25% poly(ethylene glycol) diacrylate and about 1-7% methacrylated gelatin.

[0124] Embodiment 52. The nerve repair scaffold of embodiment 51, wherein the biofunctional agent is incorporated into the wall of at least one of the microchannels.

[0125] Embodiment 53. The nerve repair scaffold of embodiment 51, wherein the biofunctional agent is coated on the walls of the microchannels.

[0126] Embodiment 54. The nerve repair scaffold of any one of embodiments 51-53, wherein the biofunctional agent comprises fibronectin, keratin, laminin, collagen, a growth factor, or a stem cell promoting factor.

[0127] Embodiment 55. The nerve repair scaffold of any one of embodiments 51-54, wherein the growth factor is brain-derived neurotrophic factor, nerve growth factor, glial cell line-derived neurotrophic factor, or neurotrophin-3, or any combination thereof.

[0128] Embodiment 56. A nerve repair scaffold described in any one of embodiments 51-55, wherein the outer diameter of the scaffold is from about 1.5 mm to about 10 mm.

[0129] Embodiment 57. A nerve repair scaffold described in any one of embodiments 51-56, wherein the length of the scaffold is 0.5 mm to 10 cm.

[0130] Embodiment 58. A nerve repair scaffold described in any one of embodiments 51-57, wherein the length of the scaffold is 5 cm to 15 cm.

[0131] Embodiment 59. A nerve repair scaffold described in any one of embodiments 51-58, wherein the plurality of microchannels comprises from about 7 to about 200 microchannels.

[0132] Embodiment 60. A nerve repair scaffold described in any one of embodiments 51-59, wherein the microchannels are hexagonal or round, or a combination thereof.

[0133] Embodiment 61. The density of the microchannels is from about 10 to about 30 microchannels / mm 2 61. The nerve repair scaffold of any one of embodiments 51-60, wherein

[0134] Embodiment 62. A nerve repair scaffold according to any one of embodiments 51-61, wherein the scaffold comprises an open volume of about 80% or more.

[0135] Embodiment 63. A nerve repair scaffold described in any one of embodiments 51-62, wherein the length of the protrusions is from about 0.1 mm to about 3 mm.

[0136] Embodiment 64. A nerve repair scaffold described in any one of embodiments 51-63, wherein the wall thickness of the microchannel is from about 10 μm to about 50 μm.

[0137] Embodiment 65. A nerve repair scaffold according to any one of embodiments 51-64, wherein the microchannels are filled with stem cells or Schwann cells.

[0138] Embodiment 66. A nerve repair scaffold described in any one of embodiments 51-65, wherein the nerve repair scaffold is 3D printed.

[0139] Embodiment 67. A method of restoring nerve function, comprising implanting the nerve repair scaffold of any one of embodiments 1-66 into a site of nerve injury in a subject in need of restoration of nerve function, thereby enabling restoration of nerve function throughout the injury site.

[0140] Embodiment 68. The method of embodiment 67, wherein the nerve is a peripheral nerve.

[0141] Embodiment 69. The method of embodiment 67 or 68, wherein the nerve is completely or partially damaged.

[0142] Embodiment 70. The method of any one of embodiments 67-69, wherein the nerve damage is caused by physical injury, disease, or surgery.

[0143] Embodiment 71. The method of any one of embodiments 67-70, wherein the nerve damage site comprises a gap between nerve endings of about 0.5 mm to about 10 cm.

[0144] Embodiment 72. The method of any one of embodiments 67-71, wherein the nerve damage site comprises a gap between nerve endings of about 5 cm to about 10 cm.

[0145] Embodiment 73. The method of any one of embodiments 67-72, wherein implanting the nerve repair scaffold comprises suturing nerve ends to the proximal and distal ends of the nerve repair scaffold.

[0146] (Addendum) (Appendix 1) a sheath having a proximal end and a distal end and containing a plurality of microchannels traversing from the proximal end to the distal end, the microchannels configured to allow neural tissue to grow through the sheath; and a first protrusion at the proximal end and a second protrusion at the distal end configured to suture neural tissue; A nerve repair scaffold comprising:

[0147] (Appendix 2) 2. The nerve repair scaffold of claim 1, wherein the shape of the microchannel is hexagonal, round, triangular, rectangular, square, pentagonal, heptagonal, octagonal, nonagonal, decagonal, elliptical, or trapezoidal.

[0148] (Appendix 3) 3. The nerve repair scaffold of claim 1 or 2, wherein the scaffold comprises about 7 to about 200 of the microchannels.

[0149] (Appendix 4) 4. The nerve repair scaffold of any one of claims 1-3, wherein the length of the scaffold is from about 0.5 cm to about 15 cm.

[0150] (Appendix 5) 5. The nerve repair scaffold of any one of claims 1-4, wherein the outer diameter is from about 1.5 mm to about 10 mm.

[0151] (Appendix 6) 6. The nerve repair scaffold of any one of claims 1-5, wherein the inner diameter of each of the microchannels is from about 150 μm to about 250 μm.

[0152] (Appendix 7) 7. The nerve repair scaffold of any one of claims 1-6, wherein the wall thickness of each of the microchannels is from about 10 μm to about 60 μm.

[0153] (Appendix 8) 8. The nerve repair scaffold of any one of claims 1-7, wherein the scaffold is formed from a biodegradable material selected from poly(ethylene glycol) diacrylate, methacrylated gelatin, methacrylated collagen, polycaprolactone, and acrylated polycaprolactone, or any combination thereof.

[0154] (Appendix 9) 9. The nerve repair scaffold of any one of claims 1-8, wherein the scaffold is formed from a mixture comprising poly(ethylene glycol) diacrylate and methacrylated gelatin.

[0155] (Appendix 10) 10. The nerve repair scaffold of claim 9, wherein the scaffold is made from about 25% poly(ethylene glycol) diacrylate and about 1-7% methacrylated gelatin.

[0156] (Appendix 11) 9. The nerve repair scaffold of claim 8, wherein the scaffold is formed from a mixture comprising poly(ethylene glycol) diacrylate and methacrylated collagen.

[0157] (Appendix 12) 12. The nerve repair scaffold of any one of claims 1-11, wherein the scaffold further comprises a biofunctional agent.

[0158] (Appendix 13) 13. The nerve repair scaffold of claim 12, wherein the biofunctional agent comprises fibronectin, collagen, laminin, keratin, a growth factor, or a stem cell promoting factor.

[0159] (Appendix 14) 14. The nerve repair scaffold of any one of claims 1-13, wherein the scaffold comprises an open volume of about 70% or more.

[0160] (Appendix 15) 15. The nerve repair scaffold of any one of clauses 1-14, wherein the scaffold is 3D printed.

[0161] (Appendix 16) a sheath having a proximal end and a distal end and containing a plurality of microchannels traversing from the proximal end to the distal end, the microchannels configured to allow neural tissue to grow therethrough; at least one of the walls of the microchannel comprises a biofunctional agent incorporated into the wall of the microchannel; Nerve repair scaffolds.

[0162] (Appendix 17) 17. The nerve repair scaffold of claim 16, wherein the biofunctional agent comprises fibronectin, keratin, laminin, collagen, a growth factor, or a stem cell promoting factor.

[0163] (Appendix 18) 18. The nerve repair scaffold of claim 17, wherein the growth factor is brain-derived neurotrophic factor, nerve growth factor, glial cell line-derived neurotrophic factor, or neurotrophin-3, or any combination thereof.

[0164] (Appendix 19) 19. The nerve repair scaffold of any one of claims 16-18, wherein the open diameter of each of the microchannels is from about 200 μm to about 500 μm.

[0165] (Appendix 20) 20. The nerve repair scaffold of any one of claims 16-19, wherein the scaffold is made from about 20% to about 30% poly(ethylene glycol) diacrylate and about 1-7% methacrylated gelatin.

[0166] (Appendix 21) 21. The nerve repair scaffold of any one of claims 16-20, wherein the scaffold is made from about 25% poly(ethylene glycol) diacrylate and about 2-10 mg / mL of methacrylated collagen.

[0167] (Appendix 22) 22. The nerve repair scaffold of any one of claims 16-21, wherein the length of the scaffold is 0.5 mm to 15 cm.

[0168] (Appendix 23) 23. The nerve repair scaffold of any one of claims 16-22, wherein the scaffold comprises an open volume of about 70% or more.

[0169] (Appendix 24) 24. The nerve repair scaffold of any one of clauses 16-23, wherein the scaffold is 3D printed.

[0170] (Appendix 25) 1. A nerve repair scaffold comprising: a sheath having a proximal end and a distal end, the sheath containing a plurality of microchannels traversing from the proximal end to the distal end, the microchannels configured to allow neural tissue growth; and a first protrusion at the proximal end and a second protrusion at the distal end configured to suture neural tissue; the scaffold further comprises a biofunctional agent; the open diameter of each of the microchannels is from about 200 μm to about 350 μm; The scaffold is made from about 15% to about 25% poly(ethylene glycol) diacrylate and about 1-7% methacrylated gelatin. Nerve repair scaffolds.

[0171] (Appendix 26) 26. The nerve repair scaffold of claim 25, wherein the biofunctional agent is incorporated into at least one microchannel wall.

[0172] (Appendix 27) 27. The nerve repair scaffold of claim 25 or 26, wherein the biofunctional agent comprises fibronectin, keratin, laminin, collagen, a growth factor, or a stem cell promoting factor.

[0173] (Appendix 28) 28. The nerve repair scaffold of any one of clauses 25-27, wherein the length of the scaffold is 0.5 mm to 15 cm.

[0174] (Appendix 29) 29. The nerve repair scaffold of any one of clauses 25-28, wherein the microchannels are hexagonal or round, or a combination thereof.

[0175] (Appendix 30) 30. The nerve repair scaffold of any one of clauses 25-29, wherein the scaffold comprises an open volume of about 70% or more.

[0176] (Appendix 31) 31. The nerve repair scaffold of any one of clauses 25-30, wherein the nerve repair scaffold is 3D printed.

[0177] (Appendix 32) 10. A method of restoring nerve function, comprising implanting the nerve repair scaffold of any one of claims 1-31 at a site of nerve injury in a subject in need thereof, thereby allowing restoration of nerve function across the injury site.

[0178] (Appendix 33) 33. The method of claim 32, wherein the nerve is a peripheral nerve.

Claims

1. an outer sheath having a proximal end and a distal end and containing a plurality of hexagonal microchannels traversing from the proximal end to the distal end, the hexagonal microchannels configured to allow neural tissue to grow through; and a first protrusion at the proximal end and a second protrusion at the distal end configured to suture neural tissue; Including, formed from a mixture including poly(ethylene glycol) diacrylate and methacrylated gelatin; The wall thickness of each of the microchannels is from about 10 μm to about 50 μm. Nerve repair scaffolds.

2. The nerve repair scaffold of claim 1 , wherein the scaffold comprises from about 7 to about 200 of the microchannels.

3. 3. The nerve repair scaffold of claim 1 or 2, wherein the length of the scaffold is from about 0.5 cm to about 15 cm.

4. The nerve repair scaffold of any one of claims 1-3, wherein the outer diameter is from about 1.5 mm to about 10 mm.

5. The nerve repair scaffold of any one of claims 1 to 4, wherein the open diameter of each of the microchannels is from about 150 μm to about 250 μm.

6. 10. The nerve repair scaffold of claim 1, wherein the scaffold is made from about 25% poly(ethylene glycol) diacrylate and about 1-7% methacrylated gelatin.

7. The nerve repair scaffold of any one of claims 1-6, wherein the scaffold further comprises a biofunctional agent.

8. The nerve repair scaffold of claim 7 , wherein the biofunctional agent comprises fibronectin, collagen, laminin, keratin, a growth factor, or a stem cell promoting factor.

9. The nerve repair scaffold of any one of claims 1-8, wherein the scaffold comprises an open volume of about 70% or more.

10. a sheath having a proximal end and a distal end and containing a plurality of hexagonal microchannels traversing from the proximal end to the distal end, the hexagonal microchannels configured to allow neural tissue to grow therethrough; formed from a mixture including poly(ethylene glycol) diacrylate and methacrylated gelatin; at least one of the walls of the hexagonal microchannel comprises a biofunctional agent incorporated into the wall of the hexagonal microchannel; The wall thickness of each of the microchannels is from about 10 μm to about 50 μm. Nerve repair scaffolds.

11. The nerve repair scaffold of claim 10 , wherein the biofunctional agent comprises fibronectin, keratin, laminin, collagen, a growth factor, or a stem cell promoting factor.

12. 12. The nerve repair scaffold of claim 11, wherein the growth factor is brain-derived neurotrophic factor, nerve growth factor, glial cell line-derived neurotrophic factor, or neurotrophin-3, or any combination thereof.

13. The nerve repair scaffold of any one of claims 10-12, wherein the open diameter of each of the microchannels is from about 200 μm to about 500 μm.

14. The nerve repair scaffold of any one of claims 10-13, wherein the scaffold is made from about 20% to about 30% poly(ethylene glycol) diacrylate and about 1-7% methacrylated gelatin.

15. The nerve repair scaffold of any one of claims 10-14, wherein the scaffold is made from about 25% poly(ethylene glycol) diacrylate and about 2-10 mg / mL methacrylated collagen.

16. The nerve repair scaffold of any one of claims 10-15, wherein the length of the scaffold is from 0.5 mm to 15 cm.

17. The nerve repair scaffold of any one of claims 10-16, wherein the scaffold comprises an open volume of about 70% or more.

18. 1. A nerve repair scaffold comprising: a sheath having a proximal end and a distal end, the sheath containing a plurality of hexagonal microchannels traversing from the proximal end to the distal end, the hexagonal microchannels configured to allow neural tissue growth; and a first protrusion at the proximal end and a second protrusion at the distal end configured to suture neural tissue; the scaffold further comprises a biofunctional agent; the open diameter of each of the hexagonal microchannels is about 200 μm to about 350 μm, and the wall thickness of each of the microchannels is about 10 μm to about 50 μm; The scaffold is made from about 15% to about 25% poly(ethylene glycol) diacrylate and about 1-7% methacrylated gelatin. Nerve repair scaffolds.

19. 20. The nerve repair scaffold of claim 18, wherein the biofunctional agent is incorporated into at least one microchannel wall.

20. 20. The nerve repair scaffold of claim 18 or 19, wherein the biofunctional agent comprises fibronectin, keratin, laminin, collagen, a growth factor, or a stem cell promoting factor.

21. The nerve repair scaffold of any one of claims 18-20, wherein the length of the scaffold is from 0.5 mm to 15 cm.

22. The nerve repair scaffold of any one of claims 18-21, wherein the scaffold comprises an open volume of about 70% or more.

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