Mesenchymal Stem Cells Attenuate Renal Fibrosis Via Exosomes-mediated Delivery Of MiRNA Let-7i-5p Antagomir

Objective:Renal fibrosis represents a primary pathological characteristic of chronic kidney disease(CKD),and serves as a common pathway and main pathological change towards renal failure.Mesenchymal stem cells-derived exosomes(MSCs-Exo)have been shown to alleviate renal fibrosis and injury,but the mechanism of MSCs-Exo induced renal protection remains unknown.In this study,our objective is to explore how exosomes,derived from mesenchymal stem cells,can affect renal fibrosis and its specific molecular mechanisms.The ultimate goal of this research is to provide evidence that can be utilized in the treatment of renal fibrosis,which is commonly associated with chronic kidney disease.Methods:In this study,possible target miRNA were first identified using GEO online database and TGF-β1 renal fibrosis model in vitro and UUO model in vivo.Then,mesenchymal stem cells(MSCs)were transfected with let-7i-5p antagonist(anti-let-7i-5p),and then exosomes were isolated from the transfected MSCs,and anti-let-7i-5p oligonucleotides were transmitted through exosomes to reduce the expression of let-7i-5p in NRK-52 E renal tubular epithelial cells and renal fibrosis in mice with unilateral ureteral obstruction(UUO).Results:1.In both NRK-52 E cells stimulated by TGF-β1 and the mouse kidneys after unilateral ureteral obstruction(UUO),we demonstrated increased level of let-7i-5p.2.In addition,MSCs-Exo can deliver anti-let-7i-5p to reduce the level of let-7i-5p in NRK-52 E cells and increase the expression of its target gene TSC1.3.MSCs/anti-let-7i-5p reduced extracellular matrix(ECM)deposition and attenuated epithelial–mesenchymal transition(EMT)process in transforming growth factor beta 1(TGF-β1)-stimulated NRK-52 E cells and in the kidneys of UUO-treated mice.Meanwhile,mice received 3.MSCs / anti-let-7i-5p displayed reduced renal fibrosis and improved kidney function when challenged with UUO.4.MSCs/anti-let-7i-5p promoted the activation the tuberous sclerosis complex subunit 1/mammalian target of rapamycin(TSC1/m TOR)signaling pathway in vivo and in vitro.Conclusions:In conclusion,exosomal anti-let-7i-5p from MSCs exerts anti-fibrotic effects in TGF-β1-induced fibrogenic responses in NRK-52 E cells in vitro as well as in UUO induced renal fibrosis model in vivo.These results provided a novel perspective on improving renal fibrosis by MSCs-Exo.