Fabrication and in vitro evaluation of 3D composite scaffold based on collagen/hyaluronic acid sponge and electrospun polycaprolactone nanofibers for peripheral nerve regeneration

Replacement of peripheral nerve autografts with tissue engineered nerve grafts will potentially resolve the lack of nerve tissue especially in patients with severe concomitant soft tissue injuries. This study attempted to fabricate a tissue engineered nerve graft composed of electrospun PCL conduit filled with collagen-hyaluronic acid (COL-HA) sponge with different COL-HA weight ratios including 100:0, 98:2, 95:5 and 90:10. The effect of HA addition on the sponge porosity, mechanical properties, water absorption and degradation rate was assessed. A good cohesion between the electrospun PCL nanofibers and COL-HA sponges were seen in all sponges with different HA contents. Mechanical properties of PCL nanofibrous layer were similar to the rat sciatic nerve; the ultimate tensile strength was 2.23 ± 0.35 MPa at the elongation of 35%. Additionally, Schwann cell proliferation and morphology on three dimensional (3D) composite scaffold were evaluated by using MTT and SEM assays, respectively. Rising the HA content resulted in higher water absorption as well as greater pore size and porosity, while a decrease in Schwann cell proliferation compared to pure collagen sponge, although reduction in cell proliferation was not statistically significant. The lower Schwann cell proliferation on the COL-HA was attributed to the greater degradation rate and pore size of the COL-HA sponges. Also, dorsal root ganglion assay showed that the engineered 3D construct significantly increases axon growth. Taken together, these results suggest that the fabricated 3D composite scaffold provide a permissive environment for Schwann cells proliferation and maturation and can encourage axon growth.