Mesenchymal stem cells
Bone and cartilage formation in the embryo involves the progeny of a small number of cells called MSCs. The most commonly used MSCs in clinical trials are umbilical cord blood derived mesenchymal stem cells (UCB‑MSCs) and autologous bone marrow MSCs (BM‑MSCs) isolated from individuals. Lee et al. found that soluble CCL5 (a chemokine) derived from BM‑MSCs,attenuated microglia immune responses with a reduction in Aβ deposition and memory impairment in APP/PS1 mice.[47] It was also reported that BM‑MSCs could produce an acute reduction in Aβ deposits and facilitate changes in key proteins required for synaptic transmission, when administrated at a young age in mice with AD, at which stage, the young mice displayed neuropathological, but not cognitive features of AD.[48] Besides the BM‑MSCs, umbilical cord blood (UCB)‑MSCs are also considered to be protective for AD. Nikolic et al. found that multiple low‑dose infusions of UCB‑MSCs markedly reduced Aβ plaques in the AD mouse model, which was associated with suppression of the CD40‑CD40L interaction.[49] Moreover, previous studies showed that transplantation of UCB‑MSCs, which was induced to
differentiate into neuron‑like cells, improved cognitive function, increased synapsin I level, and significantly reduced Aβ deposition in APP/PS1 mice by a mechanism associated with activating M2‑like microglia and modulating neuroinflammation.[50] Hence, transplantation of MSCs may be an effective therapy for AD, but till date, most evidences are obtained from animal models and further clinical trials are urgently needed.