Mechanism of rat sciatic nerve regeneration induced by human hair keratin / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the effect of human hair keratin (HHK) in peripheral nerve repair and explore the mechanism of sciatic nerve regeneration.</p><p><b>METHODS</b>Rat models of sciatic nerve damage was established by creating a 10-mm gap in the sciatic nerve, which was bridged with a HHK implant. Histological examinations of the nerve tissues were performed at different time points after the surgery.</p><p><b>RESULTS</b>During the period from 2 days to 2 weeks following HHK implantation, Schwann cells were found to undergo dedifferentiation and proliferate along the HHK implant. Three weeks after HHK implantation, numerous macrophages and megakaryocytes occurred around the HHK, and a large quantity of regenerated Schwann cells aligned in orderly fashion was seen between the fine filaments of partially degraded HHK, where axons and capillaries were also observed. Six weeks later, massive nerve fibers and capillaries developed around the HHK, and at 9 weeks, the HHK implant was substantially degraded and numerous regenerated nerve fibers occurred characterized by obvious epineurium and perineurium. Till 12 weeks after HHK implantation, HHK was almost completely degraded and replaced by the newly regenerated nerve fibers that had grown across the nerve defect.</p><p><b>CONCLUSIONS</b>HHK is an ideal material for nerve injury repair. Apocytosis plays a key role in the differentiation process of highly differentiated Schwann cells into immature Schwann cells following nerve injury. As a protective mechanism, the axons undergo enclosure and dissociation following injuries, and the intact axons give rise to growth cones that extend fibers of growing buds to competitively bind the one or more Schwann cells, but only one such but finally develops into a complete axon. The nerve fiber barrier membrane is derived from the capillary menchymal stem cells and the outmost vascular barrier membrane. The regeneration of the Schwann cells, axons and the nerve membrane is the result of self-organization through a well synchronized and coordinated mechanism.</p>

Construction of artificial nerve bridge by three-dimensional culture of interleukin-1beta- activated Schwann cells with human hair keratins / 南方医科大学学报

<p><b>OBJECTIVE</b>To culture interleukin-1beta (IL-1beta)-activated Schwann cells (SCs) with human hair keratins (HHKs) for artificial nerve bridge construction.</p><p><b>METHODS</b>SCs purified by primary culture with or without IL-1beta activation were cultured with HHKs decorated by extracellular matrix (ECM), and the artificial nerve bridge was implanted into the defect of rat sciatic nerve. The morphology of the SCs cultured with HHKs was monitored by inverted microscope, scanning electron microscope and evaluated by immunocytochemical staining, and the expression of nerve growth factor (NGF) in the sciatic nerve was observed by in situ hybridization.</p><p><b>RESULTS</b>Activated SCs showed better ability to adhere to the HHKs and grew well. The HHKs component in the artificial nerve bridge underwent degradation in the sciatic nerve defect after 3 to 4 weeks, and IL-1beta activation resulted in enhanced NGF expression in the SCs.</p><p><b>CONCLUSION</b>The constructed artificial nerve bridge by three-dimensional culture of IL-1beta-activiated SCs with HHKs decorated by ECM promotes the repair of sciatic nerve defects and accelerates sciatic nerve regeneration.</p>