VAMP4 in hypoxic adipose stem cell exosomes alleviates ischemia-reperfusion injury.

BACKGROUND: Ischemia/reperfusion injury (I/RI) impedes the progress of flap and allograft transplantation. Among various strategies to address oxidative stress (OS) and mitochondrial dysfunction associated with I/RI, exosomes derived from adipose-derived stem cells (ADSCs) subjected to hypoxia pretreatment show significant therapeutic potential. METHODS AND RESULTS: This study assessed the effects of ADSC-derived exosomes (ADSC-Ex) from normoxic and hypoxic conditions on reactive oxygen species (ROS), mitochondrial calcium ion (Ca(2+)) influx, mitochondrial potential, and cell apoptosis in an ischemia/reperfusion (I/R) model. Mass spectrometry (MS) was utilized to analyze differentially expressed proteins in hypoxic ADSC-Ex compared to normoxic controls. The functions of significantly upregulated proteins were investigated through knockdown experiments in hypoxic ADSC-Ex on alleviating I/R injury (I/RI) in HUVECs. Hypoxic ADSC-Ex significantly mitigated I/RI in vascular endothelial cells both in vitro and in vivo. This effect was associated with reduced ROS and mitochondrial Ca(2+) influx, and protection of mitochondrial potential. MS identified several proteins that were significantly upregulated in hypoxic ADSC-Ex, with Vesicle-associated membrane protein 4 (VAMP4) emerging as a pivotal molecule involved in alleviating I/RI in vascular endothelial cells. CONCLUSION: This study demonstrated that hypoxic ADSC-Ex reduced ROS and mitochondrial dysfunction in vascular endothelial cells through VAMP4, thereby attenuating I/RI. This finding might provide a new approach for treating post-transplant I/RI.