Abstract: Objective: To discuss the protective effect of velvet antler polypeptides(VAP)combined with Schwann cells(SCs) modified by glial cell line derived neurotrophic factor(GDNF)gene on the apoptosis of spinal cord neurons induced by beta-amyloid 25-35(Aβ_25-35).Methods: The spinal cord cells of fetal mice were prepared and the spinal cord neurons in logarithmic growth phase were taken; the apoptosis of spinal cord neurons was induced by Aβ_25-35.The spinal cord neurons were divided into normal cell group (the normal spinal cord neurons), induced apoptosis group (the apoptotic spinal cord neurons induced by Aβ_25-35, SCs group (the apoptotic spinal cord neurons induced by Aβ_25-35+SCs), GDNF group (the apoptotic spinal cord neurons induced by Aβ_25-35+GDNF), SCs + GDNF group (the apoptotic spinal cord neurons induced by Aβ_25-35+GDNF-transfected SCs) and VAP combination group (the apoptotic spinal cord neurons induced by Aβ_25-35+VAP combined with GDNF-transfected SCs).Flow cytometry was used to detect the apoptotic rates of spinal cord neurons in various groups; immunohistochemical staining was used to detect the number of caspase-3 positive cells in the spinal cord neurons in various groups.Results: After suspension inoculation of fetal spinal cord neurons, most of them were round at the initial stage.The flow cytometry results showed that compared with induced apoptosis group, the apoptotic rates of spinal cord neurons in SCs,GDNF,SCs+GDNF,and VAP combination groups were decreased (P<0.05). Compared with SCs+GDNF group,the apoptotic rate of spinal cord neurons in VAP combination group was decreased (P<0.05).The immunohistochemistry results showed that the expression of caspase-3 in spinal cord neurons in various groups could be found. There were no significant differences in the number of caspase-3 positive cells and cell staining between SCs group, GDNF group and SCs+GDNF group; but the number of caspase-3 positive cells in SCs group, GDNF group and SCs+GDNF group were significantly higher than that in induced apoptosis group (P<0.05).Conclusion: VAP combined with GDNF-transfected SCs has the protective effect on the apoptosis of spinal cord cells by reducing the expression of caspase-3 in spinal cord neurons.

Key words: velvet antler polypeptides, glial cell line derived neurotrophic factor, Schwann cells, spinal cord neurons