The protective effects of MSC-EXO against pulmonary hypertension through regulating Wnt5a/BMP signalling pathway

The aim of the study was to explore the mechanism of mesenchymal stem cell-derived exosomes (MSC-EXO) to protect against experimentally induced pulmonary hypertension (PH). Monocrotaline (MCT)-induced rat model of PH was successfully established by a single intraperitoneal injection of 50 mg/kg MCT, 3 weeks later the animals were treated with MSC-EXO via tail vein injection. Post-operation, our results showed that MSC-EXO could significantly reduce right ventricular systolic pressure (RVSP) and the right ventricular hypertrophy index, attenuate pulmonary vascular remodelling and lung fibrosis in vivo. In vitro experiment, the hypoxia models of pulmonary artery endothelial cell (PAEC) and pulmonary vascular smooth muscle cell (PASMC) were used. We found that the expression levels of Wnt5a, Wnt11, BMPR2, BMP4 and BMP9 were increased, but beta-catenin, cyclin D1 and TGF-beta 1 were decreased in MSC-EXO group as compared with MCT or hypoxia group in vivo or vitro. However, these increased could be blocked when cells were transfected with Wnt5a siRNA in vitro. Taken together, these results suggested that the mechanism of MSC-EXO to prevent PH vascular remodelling may be via regulation of Wnt5a/BMP signalling pathway.