Extracellular Vesicles Derived from Adipose-Derived Mesenchymal Stem Cells Alleviate Apoptosis and Oxidative Stress of Retinal Pigment Epithelial Cells Through Activation of Nrf2 Signaling Pathway

<b><i>Purpose:</i></b> To examine the potential protective effects of adipose-derived mesenchymal stem cell-derived extracellular vesicles (ASC-EVs) on ARPE-19 cells exposed to hydrogen peroxide (H₂O₂) stress and to evaluate their ability to delay retinal degeneration in Royal College of Surgeons (RCS) rats. <b><i>Methods:</i></b> ARPE-19 cells were pre-treated with ASC-EVs for 24 h, followed by exposure to 200 μM H₂O₂ for an additional 24 h. RCS rats received an intravitreal injection of phosphate-buffered saline in one eye and ASC-EVs in the other eye. <b><i>Results:</i></b> ASC-EV pretreatment significantly protected against H₂O₂ in the Cell Counting Kit-8 assay and was also effective in the lactate dehydrogenase-release assay. It notably reduced early apoptosis (Annexin V-fluorescein isothiocyanate/propidium iodide assay) and late apoptosis (Terminal Deoxynucleotidyl Transferase dUTP Nick End Labeling assay), while significantly decreasing intracellular reactive oxygen species, glutathione levels, and superoxide dismutase activity. <i>NFE2L2</i>, <i>HMOX1</i>, and <i>NQO1</i> mRNA levels, along with Nrf2, HO-1, and NQO1 protein levels, were significantly elevated with ASC-EV pretreatment. Compared with ARPE-19-derived EVs, 11 miRNAs were upregulated and 34 were downregulated in ASC-EVs. In RCS rats, intravitreal injections of ASC-EVs led to significant preservation of the outer nuclear layer and photoreceptor segments, along with increased nuclear Nrf2 expression and elevated HO-1 and NQO1 levels in the inner retina. Eyes that received intravitreal injections of ASC-EVs demonstrated significantly preserved electroretinography a- and b-wave amplitudes at 1 week post-injection, though this effect faded by 2 weeks. <b><i>Conclusions:</i></b> ASC-EVs mitigated apoptosis and oxidative stress in ARPE-19 cells subjected to H₂O₂ exposure and temporarily slowed retinal degeneration in RCS rats via Nrf2 pathway activation by miRNAs.