Hypoxic preconditioned mesenchymal stem cell-derived exosomes alleviate oxidative stress-induced cardiomyocyte...

Emerging evidence indicates that hypoxic preconditioning boosts the antioxidant and anti-apoptotic capacities of mesenchymal stem cell-derived exosomes; however, the specific mechanisms remain incompletely elucidated. This study explored the impact of hypoxia-preconditioned mesenchymal stem cell-derived exosomes (hypo-Exos) vs normoxic counterparts on the apoptotic response in cardiomyocytes triggered by oxidative stress.

To determine whether and how hypoxic preconditioning augments the cardioprotective efficacy of hypo-Exos against oxidative stress-induced cardiomyocyte apoptosis.

H9C2 cardiomyocytes were treated with hydrogen peroxide (H₂O₂) to induce oxidative injury. Assessments of cell viability, oxidative biomarkers, and apoptotic activity were conducted to evaluate the therapeutic efficacy of hypo-Exos and normoxic counterparts. High-throughput sequencing was performed to identify potential target microRNAs (miRNAs). Luciferase reporter assays were conducted to confirm selected miRNAs binding to target genes. Hypo-Exos loaded with selected miRNAs antagomirs or negative controls were administered to H₂O₂-treated H9C2 cells to validate the downstream signaling pathways involved.

Hypo-Exos significantly enhanced cell viability, reduced oxidative stress, and inhibited apoptosis of cardiomyocytes. Hypoxic preconditioning significantly increased the expression of exosomal miR-486-5p, which directly targeted the phosphatase and tensin homolog. Additionally, hypo-Exos markedly activated the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway. Moreover, deletion of miR-486-5p in hypo-Exos counteracted the anti-apoptotic effects and suppressed PI3K/Akt pathway activation.

Hypoxic preconditioning augments anti-apoptotic properties of exosomes, primarily via miR-486-5p upregulation, which mediates its function by modulating the phosphatase and tensin homolog/PI3K/Akt axis.