BDNF and Alzheimer disease: While Fleitas and colleagues [210] reported that cerebrospinal fluid from patients with AD raised apoptosis in hippocampal neural stem cells, probably as a result of a notable rise in proBDNF, p75NTR, and sortillin levels, Song and colleagues [211] showed that BDNF from mesenchymal stem cells could prevent death and improve cell survival in AD-like cells.