Successful polyethylene glycol fusion repair using stored viable peripheral nerve allografts in Sprague–Dawley and Lewis rats

We have previously shown the success of polyethylene glycol fusion repair of segmental-loss peripheral nerve injuries in rats using freshly harvested, viable peripheral nerve allografts that can conduct action potentials. Because clinical application of polyethylene glycol fusion with viable peripheral nerve allografts demands pre-transplant donor tissue storage, we developed a protocol for ex vivo storage of rat sciatic nerves as viable peripheral nerve allografts, preserving many axons for up to 5 days. The current study evaluated the in vivo use of these stored viable peripheral nerve allografts. We hypothesized that stored viable peripheral nerve allografts with viable axons would enable successful in vivo repair of segmental-loss peripheral nerve injuries via polyethylene glycol-fusion. Polyethylene glycol-fused viable peripheral nerve allografts were classified as successful if they produced significantly improved locomotor recovery, as evaluated by the sciatic functional index, within 8 weeks post-repair. Many Sprague-Dawley and Lewis rats with successfully polyethylene glycol-fused viable peripheral nerve allografts had significantly improved sciatic functional index scores beginning at 5 weeks post-operatively. There was no significant difference in the efficiency and extent of successful polyethylene glycol fusion between stored and freshly harvested viable peripheral nerve allografts. In contrast, rats with non-fused negative control viable peripheral nerve allografts showed no recovery by 8 weeks post-operatively. Additional confirmatory outcome measures included in vivo compound action potentials and assessments of axon morphometry. These results suggest that viable peripheral nerve allografts can be stored and later used for successful polyethylene glycol fusion repair of segmental-loss peripheral nerve injuries.