Abstract: 〗［Abstract］〓Objective〖HTSS〗〓To investigate the protective effect of human umbilical cord mesenchymal stem cells conditioned medium(hUCMSCsCM) against amyloid β (Aβ) induced apoptosis in cultured rat prefrontal cortical neuron and the mechanism: downregulation of the expression of cytc and cleaved caspase3 thus inhibiting the mitochondrial apoptotic pathway. 
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓Human umbilical cord mesenchymal stem cells P3 and P4 were used to collect the hUCMSCsCM. Prefrontal cortical neurons of rats cultured 7d were treated with Aβ and/or hUCMSCsCM, respectively. The neuron viability was determined by MTT assay, and the neuron apoptosis was tested by Hoechst staining. The expression of cytc and cleaved caspase3 were investigated by Western blot.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓Compared with vehiclecontrol group, Aβ(5, 10, or 20 μmol/L Aβ treated 12 h; or 10 μmol/L Aβ treated 6 h, 12 h, or 24 h) decreased the neuron viability(P＜005）and increased the neuron apoptosis(P＜005). Compared with Aβ group, hUCMSCsCM increased the neuron viability(10% and 20%, treated 12 h; P＜005）and decreased the neuron apoptosis(5%, 10% and 20%, treated 12 h; P＜005). Compared with vehiclecontrol group, Aβ upregulated the expression of cytc(P＜005) and cleaved caspase3(P＜005). Compared with Aβ group, hUCMSCsCM treatment alleviated the upregulation of cytc(5%, 10% and 20% hUCMSCsCM treated 12 h; P＜005) and cleaved caspase3(10% and 20% hUCMSCsCM treated 12 h; P＜005) in a dosedependent manner.
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓hUCMSCsCM protected against Amyloid β induced apoptosis in cultured rat cortical neuron partly through mitochondrial apoptotic pathway.

Key words: mesenchymal stem cells； amyloid &beta, ； neurons； apoptosis