TGFB1 and renal fibrosis: TGFβ1 mRNA is highly expressed in HG-M-Exo and is transferred to mesangial cells to activate the TGFβ1/Mothers against decapentaplegic homolog (Smad)3 pathway, leading to mesangial cell activation and proliferation and secretion of extracellular matrix and inflammatory cytokines, promoting mesangial expansion and renal fibrosis (106).