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Background: Alzheimer's disease (AD) is characterized by the accumulation of amyloid‐beta (Aβ) in the extracellular space, which leads to various adverse effects such as oxidative stress, neuroinflammation, mitochondrial dysfunction, tau phosphorylation, synapse loss, and neurodegeneration. Therefore, therapeutic interventions that can reduce Aβ‐toxicity and slow down the progression of cognitive dysfunction in AD have significance. One promising approach is to use extracellular vesicles (EVs) that are released by neural stem cells (NSCs) derived from human induced pluripotent stem cells (hiPSCs). These EVs contain therapeutic proteins and miRNAs that can help protect against Aβ‐induced pathological changes in the brain, providing a potential avenue for neuroprotection. Method: This study first isolated and characterized EVs secreted from hiPSC‐NSCs by chromatographic methods. Next, mature human neurons generated from 2 different hiPSC lines were exposed to 1‐µM Aβ42 oligomers with different concentrations of hNSC‐EVs. The protective effects of EVs on neurons exposed to Aβ were quantified using MTT and live/dead cell assays and counting of surviving MAP‐2+ neurons. The extent of oxidative stress was investigated via measurements of malondialdehyde (MDA) and protein carbonyls (PCs) and the expression of genes encoding iNos and Cox2. Furthermore, the expression of genes and/or proteins linked to pro‐apoptotic (Bad, Bax) and antiapoptotic (Bcl2) effects, mitochondrial respiratory chain (Nudfs6, Nudfs7, Sdha, Sdhb, Cyc1, Bcs11, Cox6a1, Atp6ap1), autophagy (Beclin 1 and MAPILC3B) were quantified. Total tau and p‐tau were also measured. Result: The addition of hiPSC‐NSC‐EVs to mature human neuronal cultures exposed to Aβ reduced the extent of Aβ‐induced neurodegeneration. When human neurons were exposed to Aβ‐42 alone, it increased pro‐apoptotic genes (Bad, Bax) and reduced the expression of an antiapoptotic gene (BCL‐2). However, adding hNSC‐EVs to Aβ‐42 exposed neurons normalized the expression of pro‐ and antiapoptotic genes to control levels, reduced oxidative stress markers, prevented Aβ‐42‐induced hyperactivation of mitochondria and decreased autophagy, reduced the phosphorylation of tau. Conclusion: Treating human neurons with hiPSC‐NSC‐EVs can significantly decrease the various pathological changes caused by Aβ exposure. Supported by a grant from the National Institute for Aging (1RF1AG074256‐01A1 to A.K.S.) [ABSTRACT FROM AUTHOR]

Background: One of the hallmarks of Alzheimer's disease (AD) is the buildup of amyloid beta-42 (Aβ-42) in the brain, which leads to various adverse effects. Therefore, therapeutic interventions proficient in reducing Aβ-42-induced toxicity in AD are of great interest. One promising approach is to use extracellular vesicles from human induced pluripotent stem cell-derived neural stem cells (hiPSC-NSC-EVs) because they carry multiple therapeutic miRNAs and proteins capable of protecting neurons against Aβ-42-induced pathological changes. Therefore, this in vitro study investigated the proficiency of hiPSC-NSC-EVs to protect human neurons derived from two distinct hiPSC lines from Aβ-42o-induced neurodegeneration., Methods: We isolated hiPSC-NSC-EVs using chromatographic methods and characterized their size, ultrastructure, expression of EV-specific markers and proficiency in getting incorporated into mature human neurons. Next, mature human neurons differentiated from two different hiPSC lines were exposed to 1 µM Aβ-42 oligomers (Aβ-42o) alone or with varying concentrations of hiPSC-NSC-EVs. The protective effects of hiPSC-NSC-EVs against Aβ-42o-induced neurodegeneration, increased oxidative stress, mitochondrial dysfunction, impaired autophagy, and tau phosphorylation were ascertained using multiple measures and one-way ANOVA with Newman-Keuls multiple comparisons post hoc tests., Results: Significant neurodegeneration was observed when human neurons were exposed to Aβ-42o alone. Notably, neurodegeneration was associated with elevated levels of oxidative stress markers malondialdehyde (MDA) and protein carbonyls (PCs), increased expression of proapoptotic Bax and Bad genes and proteins, reduced expression of the antiapoptotic gene and protein Bcl-2, increased expression of genes encoding mitochondrial complex proteins, decreased expression of autophagy-related proteins Beclin-1 and microtubule-associated protein 1 light chain 3B, and increased phosphorylation of tau. However, the addition of an optimal dose of hiPSC-NSC-EVs (6 x 10 9 EVs) to human neuronal cultures exposed to Aβ-42o significantly reduced the extent of neurodegeneration, along with diminished levels of MDA and PCs, normalized expressions of Bax, Bad, and Bcl-2, and genes linked to mitochondrial complex proteins, and reduced tau phosphorylation., Conclusions: The findings demonstrate that an optimal dose of hiPSC-NSC-EVs could significantly decrease the degeneration of human neurons induced by Aβ-42o. The results also support further research into the effectiveness of hiPSC-NSC-EVs in AD, particularly their proficiency in preserving neurons and slowing disease progression.