Gradient porous scaffolds

1. A gradient porous scaffold, comprising a plurality of biodegradable microspheres that are joined to form a scaffold, wherein the scaffold comprises a continuous porosity gradient along the length of the scaffold, wherein a first end of the scaffold has a porosity of between about 10% to about 40%, and a second end of the scaffold has a porosity of between about 65% to about 75%, wherein the gradient porous scaffold is made by a process comprising:

(a) mixing a plurality of microspheres with porogen in a desired ratio to produce a mixture, wherein the mixing comprises,

(i) mixing the plurality of microspheres with different ratios of porogen to produce a plurality of mixes;

(ii) combining the plurality of mixes to produce the mixture, such that a ratio of the porogen increases continuously along a length of the mixture;

(b) sintering the mixture for a suitable time and under suitable conditions to bond adjacent microspheres, producing a sintered mixture; and

(c) leaching porogen from the sintered mixture to produce a gradient porous scaffold having the continuous gradient along the length of the scaffold.

2. The gradient porous scaffold of claim 1 , wherein the microspheres are between about 200 μm in diameter and about 700 μm in diameter.

3. The gradient porous scaffold of claim 1 , wherein the biodegradable microspheres comprise poly(lactide-co-glycolide acid) (PLGA).

4. The gradient porous scaffold of claim 1 , further comprising a gel within the scaffold.

5. The gradient porous scaffold of claim 4 , wherein the gel comprises a hydrogel.

6. The gradient porous scaffold of claim 1 , further comprising cells and/or growth factors associated with the scaffold.

7. The gradient porous scaffold of claim 1 , wherein the scaffold has a percent accessible pore volume of between about 30% to about 60%.

8. The gradient porous scaffold of claim 7 , wherein the scaffold has an average pore size of greater than 300 μM in diameter.

9. The gradient porous scaffold of claim 8 , wherein the scaffold has an average pore size of between about 300 μm in diameter and about 500 μm in diameter.

10. The gradient porous scaffold of claim 1 , wherein the first end is present within a first region of the scaffold, wherein the first region comprises about 40% to about 70% of the length of the scaffold.

11. The gradient porous scaffold of claim 1 , wherein the second end is present within a second region of the scaffold, wherein the second region comprises about 5% to about 20% of the length of the scaffold.

12. The gradient porous scaffold of claim 10 , wherein the second end is present within a second region of the scaffold, wherein the second region comprises about 5% to about 20% of the length of the scaffold.

13. A continuous gradient porous scaffold, wherein the scaffold comprises at least 4 zones, wherein

(a) a first zone includes a first end of the scaffold and includes a porosity of about 10% at a first end of the first zone and a porosity of about 40% at a second end of the first zone;

(b) a second zone contiguous to the first zone has a porosity of between about 45% at a first end of the second zone adjacent to the first zone and a porosity of about 55% at a second end of the second zone;

(c) third zone contiguous to the second zone has a porosity of between about 55% at a first end of the third zone adjacent to the second end of the second zone and a porosity of about 65% at a second end of the third zone; and

(d) a fourth zone contiguous to the third zone and including the second end of the scaffold has a porosity of between about 65% at a first end of the fourth zone adjacent to the third zone and a porosity of about 75% at a second end of the fourth zone;

wherein the gradient porous scaffold further comprises a hydrogel within the scaffold, wherein an increased amount of the hydrogel is present in the fourth zone compared to the second zone.

14. The gradient porous scaffold of claim 13 , wherein the first zone comprises about 40% to about 70% of the length of the scaffold.

15. The gradient porous scaffold of claim 14 , wherein the second zone comprises about 5% to about 20% of the length of the scaffold.

16. The gradient porous scaffold of claim 15 , wherein the third zone comprises about 5% to about 20% of the length of the scaffold.

17. The gradient porous scaffold of claim 16 , wherein the fourth zone comprises about 5% to about 20% of the length of the scaffold.

18. The gradient porous scaffold of claim 5 , where in the hydrogel is biodegradable.