Human umbilical cord mesenchymal stem cells derived extracellular vesicles ameliorate kidney ischemia-reperfusion injury by suppression of senescent tubular epithelial cells - Experimental Study.

Background: Human umbilical cord mesenchymal stem cells derived extracellular vesicles (HUMSC-EVs) have drawn much interest in kidney transplantation, mainly because of their renoprotection by alleviating cell injury and stimulating tissue repair. Cellular senescence has been proven to play a dual regulatory role in kidney ischemia-reperfusion injury (IRI), and the regulation of HUMSC-EVs on tubular epithelial cell senescence may be a potential therapeutic target.

Materials and methods: In vitro, the hypoxia-reoxygenation of human kidney-2 cells was used to simulate kidney IRI, and the regulation of HUMSC-EVs on human kidney-2 cells was detected. Transcriptome sequencing of human kidney-2 cells was used to explore the potential regulatory mechanism. In vivo, adult male mice were divided into five groups: control group, IRI group, HUMSC-EVs treatment group, senolytics treatment group (dasatinib + quercetin), and combined treatments group (HUMSC-EVs and senolytics). Kidney function, senescent features of tubular epithelial cells, acute kidney injury, and chronic interstitial fibrosis in mice were detected to explore the renoprotection effects of HUMSC-EVs.

Results: Kidney IRI significantly up-regulated expressions of LaminB1, p53, p21, p16, senescence-associated beta-galactosidase, and apoptosis of tubular epithelial cells. In the mouse kidney IRI model, kidney subcapsular injection of HUMSC-EVs significantly improved kidney function, reducing the senescent features of tubular epithelial cells and alleviating acute kidney injury and chronic interstitial fibrosis. HUMSC-EVs mainly achieved renoprotection by regulating Bax/Bcl-2-dependent apoptosis during acute kidney injury and mostly reduced tubular atrophy and kidney interstitial fibrosis by regulating Ras-pERK-Ets1-p53 pathway-dependent cell senescence. Oral administration of senolytics also alleviated kidney injury induced by IRI, while the combined treatments of HUMSC-EVs and senolytics had better renoprotection effects.

Conclusions: The combination of HUMSC-EVs and senolytics alleviated acute kidney injury and chronic interstitial fibrosis by dynamic regulation of cell senescence and apoptosis, which provides a therapeutic potential strategy for organ preservation and tissue repair in kidney transplantation.