Human neural stem cell-derived exosomes activate PINK1/Parkin pathway to protect against oxidative stress-induced neuronal injury in ischemic stroke.

Background: Mitochondria play a critical role in oxidative stress (OS)-induced neuronal injury during ischemic stroke (IS), making them promising therapeutic targets. Mounting evidence underscores the extraordinary therapeutic promise of exosomes derived from human neural stem cells (hNSCs) in the management of central nervous system (CNS) diseases. Nonetheless, the precise mechanisms by which these exosomes target mitochondria to ameliorate the effects of IS remain only partially elucidated. This study investigates the protective effects of hNSC derived exosomes (hNSC-Exos) on neuronal damage.

Methods: Using a rat model of middle cerebral artery occlusion (MCAO) in vivo and OS-induced HT22 cells in vitro. Firstly, our research group independently isolated human neural stem cells (hNSCs) and subsequently prepared hNSC-Exos. In vivo, MCAO rats were restored to blood flow perfusion to simulate ischemia-reperfusion injury, and hNSC-Exos were injected through stereotaxic injection into the brain. Subsequently, the protective effects of hNSC-Exos on MCAO rats were evaluated, including histological studies, behavioral assessments. In vivo, H₂O₂ was used in HT22 cells to simulate the OS environment in MCAO, and then its protective effects on HT22 were evaluated by co-culturing with hNSC-Exos, including immunofluorescence staining, western blotting (WB), quantitative real time PCR (qRT-PCR). In the process of exploring specific mechanisms, we utilized RNA sequencing (RNA-seq) to detect the potential induction of mitophagy in OS-induced HT22 cells. Afterwards, we employed a series of mitochondrial function assessments and autophagy related detection techniques, including measuring mitochondrial membrane potential, reactive oxygen species (ROS) levels, transmission electron microscopy (TEM) imaging, monodansylcadaverine (MDC) staining, and mCherry-GFP-LC3B staining. In addition, we further investigated the regulatory pathway of hNSC-Exos by using autophagy inhibitor mdivi-1 and knocking out PTEN induced kinase 1 (PINK1) in HT22 cells.

Results: Administration of hNSC-Exos significantly ameliorated brain tissue damage and enhanced behavioral outcomes in MCAO rats. This treatment led to a reduction in brain tissue apoptosis and facilitated the normalization of impaired neurogenesis and neuroplasticity. Notably, the application of hNSC-Exos in vitro resulted in an upregulation of mitophagy in HT22 cells, thereby remedying mitochondrial dysfunction. We demonstrate that hNSC-Exos activate mitophagy via the PINK1/Parkin pathway, improving mitochondrial function and reducing neuronal apoptosis.

Conclusions: These findings suggest that hNSC-Exos alleviate OS-induced neuronal damage by regulating the PINK1/Parkin pathway. These reveals a novel role of stem cell-derived mitochondrial therapy in promoting neuroprotection and suggest their potential as a therapeutic approach for OS-associated CNS diseases, including IS.