Tantalum - Poly (L-lactic acid) nerve conduit for peripheral nerve regeneration

Recently, Tantalum (Ta) has been re-explored and used with bone implants to promote bone regeneration. It has previously been extensively used as a nerve suture material; however, its use was abandoned because of the formation of scar tissue. In this study, we constructed a nerve conduit made of poly (L-lactic acid) PLA (outer layer) and tantalum Ta (inner layer) to evaluate its efficiency in the promotion of peripheral nerve regeneration. Materials and methods: First, we conducted an in vitro study to evaluate the viability and proliferation of Schwann cells and rat pheocromocytoma (PC-12) cells on Ta-PLA sheets using Enhanced Cell Viability Assay Kit (EZ-CYTOX). An in vivo study was then performed using Sprague Dawley rats that were randomly divided into the following three groups: sham, PLA, and Ta-PLA nerve conduits. The nerve conduit was placed over a 10-mm gap of the rat sciatic nerve to promote nerve regeneration. The rats were observed over 12 wk with weekly sciatic functional index functional assessment. At the end of 12 wk, the nerve regeneration outcome was assessed through dorsal root ganglions (DRG) retrograde neurons labeling, histomorphometric analysis, and histological analysis. Results: The in vitro study showed significant viability and proliferation of Schwann cells in the Ta-PLA group than in the other groups. In the in vivo study, the gross findings revealed well-regenerated neural tissue in both the experimental groups with no scarring. The histological analysis showed that about 50 % of the conduits were filled with axons with a higher tendency for peripheral growth in the PLA group than for central growth within the Ta-PLA group conduits. The retrograde labeled neurons were significantly higher in Ta-PLA group than in the PLA group. Ta-PLA showed non-significant difference in the total fibers compared to the sham group. Conclusion: Tantalum proved favorable for the growth of Schwann cells.In vivo, Ta-PLA nerve conduit induced peripheral nerve regeneration without scar tissue formation.