Pulmonary arterial hypertension (PAH) is characterised by remodelling in vascular smooth muscles, and switching from contractile (differentiated) to synthetic (dedifferentiated) phenotype. This study aimed to investigate the effect of a mutated caveolin-1 (Cav1F92A) gene from bone marrow mesenchymal stem cells (rBMSCs) on phenotypic switching in the smooth muscle cells during PAH. Methods: Human pulmonary smooth muscle cells (HPASMCs) were treated with monocrotaline (MCT,1 μM), and co-cultured with Cav1F92A gene modified rBMSCs (rBMSCs/Cav1F92A). The nitric oxide (NO) production, cell adhesion, cell viability and inflammatory cytokines expression in rBMSCs was measured to evaluate the survival rate of rBMSCs and the changes of inflammatory cytokines. The concentration of NO/cGMP (nitric oxide/Guanosine-3',5'-cyclic monophosphate), the tumour necrosis factor-alpha (TNF-α), transforming growth factor-beta1 (TGF-β1) mRNA, the expression of contractile smooth muscle cells (SMCs) phenotype markers (thrombospondin-1 and Matrix Gla protein, MGP), the synthetic SMCs phenotype markers (H-caldesmon and smooth muscle gene SM22 alpha, SM22α), cell migration and the morphological changes in rBMSCs/Cav1F92A co-cultured HPASMCs were investigated. Results: Cav1F92A increased NO concentration, cell adhesion, cell viability, anti-inflammatory cytokines interleukin-4 (IL-4), and interleukin-10 (IL-10), but decreased the inflammatory cytokines interleukin-1α (IL-1α), interferon-γ (INF-γ) and TNF-α expression in rBMSCs. rBMSCs/Cav1F92A activated the NO/cGMP, down-regulated TNF-α, TGF-β1, thrombospondin-1 and MGP expression, up-regulated SM22α and H-caldesmon expression, restored cell morphology, and inhibited cell migration in MCT treated HPASMCs. Conclusions: rBMSCs/Cav1F92A inhibits switching from contractile to synthetic phenotype in HPASMCs. It also inhibits migration and promotes morphological restoration of these cells. rBMSCs/Cav1F92A may be used as a therapeutic modality for PAH.