Fresh human amniotic membrane wrapping promotes peripheral nerve regeneration in PGA-collagen tubes

Background: An artificial nerve conduit can interpose the peripheral nerve defect without donor site morbidity. However, treatment outcomes are often unsatisfactory. Human amniotic membrane (HAM) wrapping has been reported to promote peripheral nerve regeneration. We evaluated the effects of a combined application of fresh HAM wrapping and a polyglycolic acid tube filled with collagen (PGA-c) in a rat sciatic nerve 8-mm defect model. Methods: The rats were divided into three groups: (1) the PGA-c group (n = 5), in which the gap was interposed with the PGA-c; (2) the PGA-c/HAM group (n = 5), in which the gap was interposed with the PGA-c bridge, then HAM (14 x 7 mm) was wrapped around it; and (3) the Sham group (n = 5). Walking-Track recovery, electromyographic recovery, and histological recovery of the regenerated nerve were evaluated at 12 weeks postoperatively. Results: Compared to the PGA-c group, the PGA-c/HAM group showed significantly better recovery in terminal latency (3.4 +/- 0.31 ms vs. 6.6 +/- 0.72 ms, p < 0.001), compound muscle action potential (0.19 +/- 0.025 mV vs. 0.072 +/- 0.027 mV, p < 0.01), myelinated axon perimeter (15 +/- 1.3 mu m vs. 8.7 +/- 0.63 mu m, p < 0.01), and g-ratio (0.69 +/- 0.0089 vs. 0.78 +/- 0.014, p < 0.001). Conclusion: This combined application highly promotes peripheral nerve regeneration and may be more useful than PGA-c alone.