Administrating bone marrow mesenchymal stem cells to treat the experimental pulmonary arterial hypertension in rats

Abstract

To explore the therapeutic effect and mechanisms of bone marrow-derived mesenchymal stem cells (MMSCs) transplantation treating pulmonary arterial hypertension (PAH) in rats models. MMSCs collected from SD rat were isolated and cultured in vitro, then Hoechst 33342 staining was performed. Eighty healthy male Sprague-Dawley rats were randomly divided into 3 groups: pulmonary arterial hypertension group (group H, 30 rats), MMSCs transplanted group (group M, 30 rats) and normal control group (group C, 20 rats). The rats in groups H and M were given subcutaneous injection of monocrotaline (50 mg/kg) respectively to induce the model of PAH. At Day 22 post-induction, the rats in group M received sublingual intravenous injection of 1 ml MMSCs at the concentration of 5 x 10(6)/ml while the rats in groups H and C were administered with equal amount of cell culture medium respectively. General observation was made about all groups and survival information were collected after another 4 weeks. At Day 21, 4 rats from each group were sacrificed. And the rats in all groups were sacrificed at Day 49. The survival rate, mean pulmonary artery pressure (mPAP) and right ventricle hypertrophy index (RVHI) were determined. The microstructural alteration of small pulmonary vessel and immunohistochemistry and microvessel density assay of vascular VIII factor-related antigen were performed. At the end of the experiment, the survival rates were 50% (15/30) and 90% (27/30) in groups H and M respectively (P < 0.01). At Day 21, mPAP were (39.1 +/- 2.5) and (38.5 +/- 2.1) mm Hg in group H and M respectively, and RVHI were (34.0 +/- 3.1)% and (33.8 +/- 2.6)% in groups H and M respectively. The parameters in both groups were higher than those in group C [(15.2 +/- 1.7) mm Hg and (24.7 +/- 2.1)%, both P < 0.01]. At Day 49, mPAP were (42.7 +/- 2.3) and (24.7 +/- 2.1) mm Hg in group H and M respectively (P < 0.01), and RVHI were (45.1 +/- 3.4)% and (38.8 +/- 3.2)% in group H and group M respectively (P < 0.01). As compared with group H, the morphological metrological indices of small pulmonary arteries significantly improved in group M. The Hoechst 33342 staining showed MMSCs were colonized in lungs and differentiated into large number of neovascularization, forming plentiful collateral circulations in lung. The pulmonary arterial remodeling was reversed in group M. Immunohistochemistry also confirmed the finding that a large scale of neovascularization took place in rat lungs in group M. Microvessel density in group M [(5.2 +/- 0.8)/HP] was significantly higher than that in group H [(1.4 +/- 0.5)/HP, P < 0.01]. MMSC transplantation may reverse pulmonary vascular remodeling through differentiation, neovascularization and small pulmonary arterial repair. It decreases pulmonary arterial pressure, effectively slows down even reverse monocrotaline-induced PAH progression.