In the monocrotaline-induced experimental model of PAH used herein, MSC therapy reduced right ventricular systolic pressure, histological damage and smooth muscle cell thickening, CD68+ macrophage density in lung tissue, lung arteriolar and plasma VEGF levels, total lung collagen, mRNA levels of procollagen type I, type III, and TGF-β in lung fibroblast culture, and inflammatory and anti-apoptotic markers in lung tissue. This evidence concerns the gene TGFB1 and pulmonary arterial hypertension.