Alzheimer’s disease (AD) is one of the most common causes of dementia. Despite several
decades of research in AD, there is no standard disease- modifying therapy available and currentlyapproved
drugs provide only symptomatic relief. Stem cells hold immense potential to regenerate damaged
tissues and are currently tested in some brain-related disorders, such as AD, amyotrophic lateral
sclerosis (ALS) and Parkinson’s disease (PD). We review stem cell transplantation studies using preclinical
and clinical tools. We describe different sources of stem cells used in various animal models
and explaining the putative molecular mechanisms that can rescue neurodegenerative disorders. The
clinical studies suggest safety, efficacy and translational potential of stem cell therapy. The therapeutic
outcome of stem cell transplantation has been promising in many studies, but no unifying hypothesis
can convincingly explain the underlying mechanism. Some studies have reported paracrine effects exerted
by these stem cells via the release of neurotrophic factors, while other studies describe the immunomodulatory
effects exerted by the transplanted cells. There are also reports which indicate that stem
cell transplantation might result in endogenous cell proliferation or replacement of diseased cells. In
animal models of AD, stem cell transplantation is also believed to increase expression of synaptic proteins.
Keywords: Aging, dementia, differentiation, neurodegeneration, synaptogenesis, proliferation, therapeutics, transplantation.
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