Induced pleuripotent stem cells
Induced pleuripotent stem cells (iPSC) are mature and genetically reprogrammed cells so that they return to their embryonic state. Because iPSCs can differentiate into all cell types,including neural cells, providing iPSC‑derived cell replacement in AD (by employing AD patient‑specific iPSC‑derived neurons) is a promising approach to treat this disease.[51] It was reported that AD‑iPSC‑derived neurons exhibited lower levels of Aβ, higher tau phosphorylation, and active glycogen synthase kinase 3β (aGSK‑3β) and β‑secretase inhibitors that caused a significant reduction in pTau and aGSK‑3β levels.[52] It suggests the potential therapeutic effects of iPSCs for AD but further investigations are required to prove this statement. Since newer stem cells are being continuously developed for AD therapy, the selection of appropriate stem cells is very important. Although ESCs have the potential for differentiation,the risk of tumorigenesis as well as the ethical issues involved have significantly limited their clinical applications. The rarity of their source and the complexity of management of AD utilizing stem cells, are limitations encountered in the clinical applicability of NSCs despite the absence of tumorigenesis and immunogenicity while using them. MSCs can be induced to differentiate into neurons. This can compensate for the limitations prevalent in the use of ESCs and NSCs. MSCs are considered as the stem cells with the greatest potential to be beneficial in AD therapy. The evidence, however, mainly comes from animal studies and clinical trials are lacking to confirm their safety and reliability. iPSCs do not have ethical issues associated with ESCs but cannot avoid new tumor formation.