Experimental study of repairing peripheral nerve damage with conduit made of human hair keratin

Objective To evaluate the effect of conduits made of human hair keratin (HHK) in repairing injured peripheral nerve. Methods Twenty-five normal New Zealand rabbits were used in this study, which were divided into 3 groups including a control group (n=5) and 2 experiment groups. The tibial nerves of rabbits in the 2 experiments groups were transected to create a 10-mm gap, then were either routinely sutured (group II, n=10) or repaired by inserting both nerve stumps into the lumen of the conduit, followed by suturing the epineurium of the nerve stumps with HHK conduits using 9-0 nylon (group III, n=10). Electrophysiological, anatomic and histological examinations were performed at different time points after surgery. Results Noteworthy improvement in healing could be seen from electrophysiological results of group III, in which HHK conduits were partially degraded and embedded in white tissue, crisp and fragile. Large amount of infantile myelinated nerve fibers and schwann cells were observed under optical microscope to regenerate around HHK, which was partially degraded and absorbed, 92 dpostoperatively. One year after the operation, the severed tibial nerves were perfectly repaired and HHK completely degraded. Transmission electron microscopy identified Schwann cell proliferation and myelinization around HHK 92 d after operation, but the delamination of the myelin was not manifest until observed with greater magnifications. There were nerve fibrils in the myelin, where organelles such as mitochondrion could be seen. Conclusion As an ideal material for nerve injury repair, HHK conduits can guide tibial nerve elongation across a 10-mm gap.