Human umbilical cord mesenchymal stem cells‐derived exosomal circDLGAP4 promotes angiogenesis after cerebral ischemia–reperfusion injury by regulating miR‐320/KLF5 axis

Abstract Accumulating evidence suggests that human umbilical cord mesenchymal stem cell‐derived exosomes (hUC‐MSCs‐Exos) are a promising therapeutic strategy for cerebral ischemia–reperfusion injury (CIRI). However, the underlying mechanism remains unclear. hUC‐MSCs‐Exos were identified by electron microscopy, NTA, and Western blotting. In the hypoxia/reoxygenation (H/R) cell model, human brain microvascular endothelial cells (HBMECs) were cocultured with hUC‐MSCs‐Exos. Then, cell viability, migration, apoptosis, and tube formation were measured by MTT, flow cytometry, transwell, and tube formation assays. RT‐qPCR and Western blotting were used to detect the changes in RNA and protein. RNA pull‐down and dual luciferase reporter assays confirmed the relationship between circDLGAP4, miR‐320, and KLF5. Ischemia–reperfusion (I/R) rat model was established for in vivo experiments. hUC‐MSCs‐Exos increased the expression levels of circDLGAP4 and KLF5 but decreased miR‐320 in H/R‐treated HBMECs by transferring exosomal circDLGAP4. Knockdown of circDLGAP4 in hUC‐MSCs‐Exos reversed the promoting effects of hUC‐MSCs‐Exos on cell viability, migration, and tube formation in H/R‐treated HBMECs in vitro and also abolished the protective effects of hUC‐MSCs‐Exos on cerebrovascular injury in I/R rats. Mechanistically, exosomal circDLGAP4 negatively regulated miR‐320 in HBMECs, which directly bound to KLF5. In addition, the downregulation of miR‐320 could reverse the regulatory effect of exosomal shcircDLGAL5 in H/R‐treated HBMECs by upregulating KLF5. hUC‐MSCs‐Exos‐derived circDLGAP4 reduced cerebrovascular injury by regulating miR‐320/KLF5 signaling. These results provide a stem cell‐based approach to treat CIRI.