The results of animal experiments by Lang and Dai [111] showed that BM-MSCs could significantly alleviate renal fibrosis in a diabetic nephropathy rat model, and the mechanism may be associated with the inhibition of the TGF-β1/Smad3 pathway, decreased PAI-1 protein expression, reduced ECM accumulation, and the balance of the fibrinolytic system. Here, SMAD3 is linked to renal fibrosis.