Permeable guidance channels containing microfilament scaffolds enhance axon growth and maturation

Successful peripheral nerve regeneration is still limited in artificial conduits, especially for long lesion gaps. In this study, porous poly(l-lactide-co-dl-lactide, 75:25) (PLA) conduits were manufactured with 16 poly(l-lactide) (PLLA) microfilaments aligned inside the lumen. Fourteen and 18 mm lesion gaps were created in a rat sciatic nerve lesion model. To evaluate the combined effect of permeable PLA conduits and microfilament bundles on axon growth, four types of implants were tested for each lesion gap: PLA conduits with 16 filaments; PLA conduits without filaments; silicone conduits with 16 filaments; and silicone conduits without filaments. Ten weeks following implantation, regen- eration within the distal nerve was compared between cor- responding groups. Antibodies against the markers S100, calcitonin gene related peptide (CGRP), RMDO95, and P0 were used to identify Schwann cells, unmyelinated axons, myelinated axons, and myelin, respectively. Results demon- strated that the filament scaffold enhanced tissue cable for- mation and Schwann cell migration in all groups. The fila- ment scaffold enhanced axonal regeneration toward the distal stump, especially across long lesion gaps, but signifi- cance was only achieved with PLA conduits. When com- pared to corresponding silicone conduits, permeable PLA conduits enhanced myelinated axon regeneration across both lesion gaps and achieved significance only in combina- tion with filament scaffolds. Myelin staining indicated PLA conduits supported axon myelination with better myelin quantity and quality when compared to silicone conduits. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 75A: 374 -386, 2005