Exosomal <scp>miR</scp> ‐26a‐5p From Urine‐Derived Stem Cells Mitigates Renal Fibrosis via Targeting <scp>NRAS</scp>

Renal fibrosis (RF) is a pivotal pathological feature in the progression of chronic kidney disease (CKD), yet its underlying mechanisms remain incompletely elucidated. Urine-derived stem cells (USCs) exhibit significant potential in tissue repair due to their robust paracrine function. This study aimed to investigate whether miRNAs derived from USC-derived exosomes (USC-Exos) can inhibit RF and to elucidate the underlying molecular mechanisms. Based on preliminary research, miR-26a-5p was identified as a key regulatory molecule through miRNA high-throughput sequencing of USC-Exos. Integrative transcriptomic and single-cell sequencing analyses revealed the expression characteristics and functional networks of its potential target gene, Nras, during the RF process. Subsequently, dual-luciferase reporter gene assays confirmed that miR-26a-5p directly targets NRAS and negatively regulates its expression, thereby inhibiting fibroblast proliferation, migration, and the expression of fibrotic markers α-SMA and Collagen I. Further mechanistic studies demonstrated that miR-26a-5p also suppresses the activation of the MAPK signaling pathway and mechanical signaling molecules (including PTK2, SRC, RHOA, and ROCK1), reduces nuclear translocation of YAP protein, and inhibits F-actin polymerization. Animal experiments confirmed that exosome-delivered miR-26a-5p significantly attenuates renal histopathological damage, reduces collagen deposition, and downregulates the expression of various fibrosis-related molecules. This study elucidates that miR-26a-5p from USC-Exos alleviates RF progression by targeting NRAS, inhibiting the MAPK signaling pathway, and suppressing mechanical microenvironment activation, providing a potential novel strategy for clinical treatment.