Comparing FK-506 with Basic Fibroblast Growth Factor (b-FGF) on the Repair of a Peripheral Nerve Defect Using an Autogenous Vein Bridge Model

Objective: The limited availability of donor sites for nerve grafts and the morbidity associated with their harvesting serve as motivating factors to actively conduct research to find alternatives to the status quo. Experimental and clinical studies have shown that a vein segment used to bridge a peripheral nerve defect leads to a functional nerve repair. Both FK-506 and b-FGF have been reported to enhance peripheral nerve regeneration. This study compared the effects of FK-506 with that of b-FGF on peripheral nerve regeneration in a rat autogenous vein graft conduit model. Methods: The main trunk of the right sciatic nerve was transected and bridged by an autogenous vein in 30 rats. Small osmotic pumps were placed just proximal to the anastomoses. Groups of 10 rats were assigned to receive saline solution, b-FGF (2,000 units), or FK-506 (0.5 mg/kg/day) via the osmotic pumps for 2 weeks. Sciatic nerve regeneration was evaluated by sensory function, walking track analysis, electrophysiologic studies, and light microscopic evaluation. Results: On post-operative day 90, there was a statistically significant difference (p < .005) in nerve regeneration between the rats who received saline compared with those who received FK-506 or b-FGF. This was determined using sensory function tests, sciatic function index, and electrophysiologic studies. The number of nerve axons, as determined by histological analysis, revealed there were significantly more nerve fibers which were regenerated in both experimental groups (FK-506 and b-FGF) when compared with rats who received saline. There was no statistically sigrtificant difference in the number of nerve axons that regenerated in rats injected with FK-506 vs. rats injected with b-FGF. Conclusion: FK-506 and b-FGF promote similar nerve regeneration in rats compared with control.