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>

The Genetic Stability of Replicating HBV Transgenic Mice / 中国生物工程杂志

Objective:To improve the genetic stability of HBV gene in transgenic mice.Methods:HBV transgenic mice were bred by backcross and double cross.The HBV gene expression and replication were studied with real-time PCR,ELISA and chemiluminescence.Results:The HBV transgenic mice have stably bred to 23rd generation.The serum HBsAg level is 4122.31?2044.74IU/ml;The rate of HBV transgenic mice whose serum HBV DNA reach 104~106copies/ml was 93.93%.The HBV replication and expression were improved markedly.There is no difference between male and female mice about serum HBsAg level.Conclusion:After breeding the HBV gene was expressed stably with high-level in transgenic mice.