Superior axonal regeneration of non-commercially available PLA/PCL conduits vs commercially available PGA and collagen nerve conduits for the treatment of a rat sciatic nerve defects: A preliminary report.

Background: Bioabsorbable nerve conduits have recently emerged as alternatives to autologous nerve grafts in peripheral nerve defects. Two types of nerve conduits have thus far been approved for clinical use in Japan: a polyglycolic acid (PGA) conduit and a collagen conduit. However, no studies have yet compared their efficacy in peripheral nerve reconstruction. This study aimed preliminarily to compare the efficacy of three bioabsorbable nerve conduits, PGA and collagen conduits, and a poly-L-lactide and polycaprolactone (PLA/PCL) conduit, in a rat sciatic nerve gap model.

Methods: Twenty-three rats were assigned to five treatment groups: control (no treatment), PGA conduit, collagen conduit, PLA/PCL conduit, and autograft. Functional recovery was assessed based on improvements in the sciatic functional index (SFI) and histological gastrocnemius muscle atrophy. Axonal regeneration and the luminal structure of the conduits were evaluated histologically 12 weeks post-treatment.

Results: The PLA/PCL conduit group exhibited superior functional recovery compared to the PGA and collagen groups, but slightly inferior results to the autograft group. Axonal regeneration was greater in the PLA/PCL group compared to the PGA and collagen groups, and comparable to the autograft group. In the PLA/PCL group, only the inner layer of the lumen was rapidly absorbed, while the outer layer remained due to its very slow degradation, ultimately allowing the lumen to expand. The PLA/PCL conduit maintained luminal stability without collapsing, unlike the PGA and collagen conduits, which showed significant narrowing due to material degradation.

Conclusion: The PLA/PCL nerve conduit demonstrated superior axonal regeneration and functional recovery preliminarily compared to PGA and collagen conduits, attributable to its slower degradation and superior maintenance of the luminal structure, indicating its potential as an effective alternative to autologous nerve grafts.