Human umbilical cord mesenchymal stem cell-derived exosomes alleviate renal ischemia/reperfusion injury in rats by regulating SLC7A11/GPX4 pathway

To investigate the effect and mechanism of human umbilical cord mesenchymal stem cell-derived exosomes（HucMSCs-exos）on renal ischemia/reperfusion（I/R）injury in rats based on ferroptosis-related SLC7A11/GPX4 pathway.

HucMSCs were cultured and exosomes were obtained through differential centrifugation. The morphology of exosomes was observed by transmission electron microscopy, and the particle size was detected by nanoparticle tracking technology. Western blotting was used to determine the expression levels of surface marker proteins. The rat model of renal I/R injury was established by clamping both kidneys for 45 min, followed by reperfusion for 24 h. Thirty male SD rats（7 to 8 weeks old, 200 to 230 g）were randomly divided into 5 groups（n=6）: Sham group, Sham+erastin group（SLC7A11 inhibitor）, I/R group, Exo group, and Exo+erastin group. The Sham+erastin and Exo+erastin groups were intraperitoneally injected with erastin 10 mg/kg 30 min before modeling. The Exo group and Exo+erastin group were injected with HucMSCs-exos 20 μg via caudal vein 15 min before renal pedicle clamping. The renal samples were harvested 24 h after recovery and reperfusion. The levels of serum creatinine（Cr）and blood urea nitrogen（BUN）were detected. HE staining was employed to observe the pathological changes in the kidney tissue, and Paller score were calculated. The levels of ferroptosis-related markers, divalent ferrous ion（Fe²⁺）, malondialdehyde（MDA）, reactive oxygen species（ROS）and glutathione（GSH）in the renal tissues were detected. Western blotting was used to assess the expression levels of the ferroptosis-related protein SLC7A11 and glutathione peroxidase 4（GPX4）in the kidney tissue.

Compared with the Sham group, increased serum BUN and Cr levels（P<0.05）, obvious pathological injury in kidney tissue, elevated Paller score, Fe^2＋ and MDA contents（P<0.05）, increased ROS level（P<0.05）, and decreased GSH content and SLC7A11 and GPX4 protein levels（P<0.05）were observed in the I/R group. Exo treatment reversed above changes when compared with the I/R group（all P<0.05）. The protective effects of HucMSCs-exo on ferroptosis and renal I/R injury were significantly attenuated by administration of erastin, a SLC7A11 inhibitor.

HucMSCs-exos can significantly attenuate renal I/R injury and play a protective role, and its mechanism may be related to the inhibition of ferroptosis by up-regulating the SLC7A11/GPX4 pathway.