Mesenchymal stem cells ameliorate diabetic glomerular fibrosis in vivo and in vitro by inhibiting TGF-β signalling via secretion of bone morphogenetic protein 7

Purpose: To investigate whether mesenchymal stem cells (MSCs) could inhibit transforming growth factor beta (TGF-β) signalling pathway by paracrine action. Methods: Bone marrow–derived MSCs were transplanted to streptozotocin-induced diabetic rats via tail vein. MSC-conditioned media were used with a model of mesangial cell fibrosis induced by high glucose in vitro. Results: At 8 weeks after MSC treatment, the renal function and the glomerulosclerosis as revealed by periodic acid Schiff stain was dramatically attenuated. The expression of collagen I, collagen IV and α-smooth muscle actin (SMA) in diabetic kidney was decreased, and E-cadherin increased after MSC treatment. The TGF-β signalling pathway was suppressed both in vivo and in vitro. MSCs secreted a significant amount of bone morphogenetic protein 7 (BMP7), in vitro, MSC-conditioned media inhibited TGF-β signalling stimulated by high glucose, and BMP7 neutralizing antibody blocked the inhibitory effect of MSC-conditioned media. Conclusion: MSCs ameliorated glomerular fibrosis in vivo and in vitro by inhibiting TGF-β/Smad signalling pathway via secretion of BMP7.