As the most common form of dementia and a progressive neurodegenerative disorder, Alzheimer’s disease (AD) affects over 10% world population with age 65 and older. The disease is neuropathologically associated with progressive loss of neurons and synapses in specific brain regions, deposition of amyloid plaques and neurofibrillary tangles, neuroinflammation, blood–brain barrier (BBB) breakdown, mitochondrial dysfunction, and oxidative stress. Despite the intensive effort, there is still no cure for the disorder. Stem cell-derived exosomes hold great promise in treating various diseases, including AD, as they contain a variety of anti-apoptotic, anti-inflammatory, and antioxidant components. Moreover, stem cell-derived exosomes also promote neurogenesis and angiogenesis and can repair damaged BBB. In this review, we will first outline the major neuropathological features associated with AD; subsequently, a discussion of stem cells, stem cell-secreted exosomes, and the major exosome isolation methods will follow. We will then summarize the recent data involving the use of mesenchymal stem cell- or neural stem cell-derived exosomes in treating AD. Finally, we will briefly discuss the challenges, perspectives, and clinical trials using stem cell-derived exosomes for AD therapy.
Alzheimer’s disease (AD) is the most prevalent neurodegenerative disease and a leading cause of dementia. Although the amyloid-β (Aβ) peptide is deemed a crucial driver of AD, there are no effective therapeutics available to treat Aβ-caused neurotoxicity. Exosomes are extracellular vesicles with a size range of 30 – 150 nanometers in diameter. Stem cell-derived exosomes are a potential therapeutic in AD, while exosomes isolated from normal stem cell cultures generally have a low yield. Here, we studied the exosomes secreted by the rat neural stem cells in the presence of heat shock (HS) stimulus. Nanoparticle tracking analysis confirmed HS-derived exosomes exhibit significantly higher concentration and larger diameter in comparison to the non-heat shock (NHS)-derived exosomes. Mass spectrometric studies of exosomal proteins reveal that HS-derived exosomes contained fewer diverse proteins than NHS-derived exosomes. GO enrichment analysis of the proteins suggested that the top two biological functions of the proteins in HS-derived exosomes are involved in the negative regulation of apoptotic process and positive modulation of DNA repair. Importantly, the therapeutic efficacy of the NHS- and HS-derived exosomes were tested in a cell culture model of AD: HS-derived exosomes exhibited greater neuroprotection against not only oxidative stress but also amyloid-β (Aβ) induced neurotoxicity compared to NHS-derived exosomes. These data indicate that in response to HS, neural stem cells increase exosome production and alter exosome morphology and cargo to confer better neuroprotection against oxidative stress and Aβ caused neurotoxicity, suggesting that HS-induced exosomes from neural stem cells can be a therapeutic reagent for AD and possibly other neurological disorders.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.