Aligned scaffolding system for skeletal muscle regeneration

1. An anisotropic muscle implant comprising:

(a) a biodegradable scaffold comprising a plurality of fibers oriented along a longitudinal axis, wherein said fibers comprise:

(i) a natural polymer; and

(ii) a synthetic polymer,

wherein said natural polymer and said synthetic polymer are in a ratio of between 2:1 and 1:2 by weight; and

(b) mammalian myotubes in said scaffold and oriented along said longitudinal axis of said fibers,

wherein said scaffold has an ultimate tensile strength along said longitudinal axis that is between 1 and 6 MPa greater than an ultimate tensile strength along an axis perpendicular to said longitudinal axis, measured with a crosshead speed of 0.5 millimeters per second at room temperature under wet condition.

2. The implant of claim 1 , wherein said plurality of fibers is oriented along said longitudinal axis such that 70% or more of the fibers are at an angle of 50 degrees or less from said longitudinal axis.

3. The implant of claim 1 , wherein said myotubes are oriented along said longitudinal axis such that 70% or more of the fibers are at an angle of 50 degrees or less from said longitudinal axis.

4. The implant of claim 1 , wherein said fibers have an average diameter of between 100 and 1000 nanometers.

5. The implant of claim 1 , wherein said natural polymer is selected from the group consisting of collagen and elastin; and said synthetic polymer is selected from the group consisting of polycaprolactone (PCL), poly( D,L -lactide-co-glycolide) (PLGA), polylactide (PLA), poly(lactide-co-captrolactone) (PLCL), and combinations thereof.

6. The implant of claim 1 , wherein said fibers comprise collagen and polycaprolactone (PCL).

7. The implant of claim 1 , wherein said myotubes express desmin, myoD and myosin heavy chain (MHC).

8. The implant of claim 1 , wherein said myotubes comprise an oriented F-actin structure.

9. A method of forming a biodegradable scaffold, comprising:

electrospinning a solution comprising a biodegradable scaffold material onto a grounded mandrel to form a plurality of fibers oriented along a longitudinal axis, said fibers comprising a natural polymer and a synthetic polymer, wherein said natural polymer and said synthetic polymer are in a ratio of between 2:1 and 1:2 by weight; and

crosslinking said fibers to form said scaffold,

wherein said scaffold has an ultimate tensile strength along said longitudinal axis that is between 1 and 6 MPa greater than an ultimate tensile strength along an axis perpendicular to said longitudinal axis, measured with a crosshead speed of 0.5 millimeters per second at room temperature under wet condition.

10. The method of claim 9 , wherein said natural polymer is selected from the group consisting of collagen and elastin; and said synthetic polymer is selected from the group consisting of polycaprolactone (PCL), poly( D,L -lactide-co-glycolide) (PLGA), polylactide (PLA), poly(lactide-co-captrolactone) (PLCL), and combinations thereof.

11. The method of claim 9 , wherein said fibers comprise collagen and polycaprolactone (PCL).

12. The method of claim 9 , wherein said crosslinking step is carried out in a vapor of 2.5% glutaraldehyde solution.

13. A method of forming an anisotropic muscle implant comprising:

providing skeletal muscle cells;

seeding said skeletal muscle cells on a scaffold comprising oriented fibers, wherein said fibers comprise:

(i) a natural polymer; and

(ii) a synthetic polymer,

wherein said natural polymer and said synthetic polymer are in a ratio of between 2:1 and 1:2 by weight, said seeding comprising growing said cells on said scaffold in a growth medium; and then

forming oriented myotubes from said skeletal muscle cells, said forming comprising differentiating said skeletal muscle cells that have been seeded onto said scaffold in a fusion medium, thereby forming said anisotropic muscle implant,

wherein said scaffold has an ultimate tensile strength along said longitudinal axis that is between 1 and 6 MPa greater than an ultimate tensile strength along an axis perpendicular to said longitudinal axis, measured with a crosshead speed of 0.5 millimeters per second at room temperature under wet condition.

14. The method of claim 13 , wherein said skeletal muscle cells comprise myoblasts.

15. The method of claim 13 , wherein said

natural polymer is selected from the group consisting of collagen and elastin; and said synthetic polymer is selected from the group consisting of polycaprolactone (PCL), poly( D,L -lactide-co-glycolide) (PLGA), polylactide (PLA), poly(lactide-co-captrolactone) (PLCL), and combinations thereof.

16. The method of claim 13 , wherein said fibers comprise collagen and polycaprolactone (PCL).

17. The method of claim 13 , wherein said seeding step is carried out by growing said cells on said scaffold from 0-4 days.

18. The method of claim 13 , wherein said forming step is carried out by differentiating said cells in a differentiation medium from 1-8 days.

19. The method of claim 13 , wherein said myotubes express desmin and myoD.

20. The method of claim 13 , wherein said myotubes comprise an oriented F-actin structure.

21. A method of treating a subject in need of skeletal muscle reconstruction comprising implanting the anisotropic muscle implant of claim 1 into said subject.

22. The implant of claim 1 , wherein said fibers have an average diameter of between 200 and 750 nanometers.

23. The implant of claim 1 , wherein said natural polymer and said synthetic polymer are in a ratio of 1:1 by weight.

24. The method of claim 9 , wherein said fibers have an average diameter of between 200 and 750 nanometers.

25. The method of claim 9 , wherein said natural polymer and said synthetic polymer are in a ratio of 1:1 by weight.

26. The method of claim 13 , wherein said fibers have an average diameter of between 200 and 750 nanometers.

27. The method of claim 13 , wherein said natural polymer and said synthetic polymer are in a ratio of 1:1 by weight.