BACKGROUND:Human umbilical cord mesenchymal stem cells are similar to bone marrow mesenchymal stem cells, which can directional y differentiate into neuron-like cells, secrete various cytokines, and provide the base for nerve regeneration. ＜br> OBJECTIVE:To study the role of chitosan composite nerve conduit carrying umbilical cord mesenchymal stem cells in nerve end-to-side anastomosis. ＜br> METHODS:Thirty while rabbits were randomized into three groups. The central branch of the right posterior peroneal nerve were cut and proximal y ligated, and then sutured evaginably to the muscle. In the control group, the distal end of the common peroneal nerve were anastomosed into the tibial nerve at 30°-45°;in the stenting group, the chitosan conduit was bridged at the same interval and angle into the end-to-side anastomosis site between the tibial nerve and peroneal nerve;in the cel-stenting group, the chitosan conduit carrying human umbilical cord mesenchymal stem cells was bridged at the same interval and angle into the end-to-side anastomosis site between the tibial nerve and peroneal nerve. After 12 weeks, gross observation, neurophysiological examination and anti-S-100 immunohistochemistry detection were performed. ＜br> RESULTS AND CONCLUSION:After 12 weeks of operation, in the cel-stenting group, the conduit degraded completely, the nerve diameter was similar to that of the normal peroneal nerve, and the motor nerve conduction velocity was higher than that in the control and stenting groups (P＜0.01). Anti-S-100 immunohistochemistry results showed that a great amount of brownish red Schwann cells arranged around the regenerated nerve fibers in the cel-stenting group, while there was few and sparse brownish red substance, and the Schwann cells grew worse in the stenting and control groups. These findings suggest that umbilical cord mesenchymal stem cells have an obvious role in promoting nerve regeneration, induce bud growth, accelerate the growth rate of regenerated fibers, and improve growth and maturity of Schwann cells.