Umbilical Cord Blood Mesenchymal Stem Cells Transplantation In Treatment Of Pulmonary Hypertension In Rats

Pulmonary arterial hypertension(PAH) is a progressive disease manifested byincreased pulmonary vascular resistance,endothelium injury and artery remodeling,whichwill lead to right ventricular hypertrophy(RVH),heart failure and even to death.There is still no ideal therapeutic strategy for PAH,meanwhile some relatively effectivetreatments are still limited because of their high price and significant side effects.Thetherapy of transplantation of stem cells especially MSCs has a special advantage forcardiovascular disease,and is likely to be a new treatment for PAH. It is probably becauseof the characteristics that it can differentiate into vascular endothelial cells, improveendothelial cells secretion, reverse pulmonary vascular remodeling etc.In the present study,we establish a model of severe PAH in the mouse by A-VF+MCTmethod,then,we intravenous transfusion of ex vivo-expanded umbilical cord blood derivedMSCs to evaluate the effect of therapy for PAH in order to provide the theoreticalevidence and to explore a new therapeutic way for PAH. Part I Establishment of pulmonary arterial hypertension model by A-VF+MCTmethod in ratsObjective:To establish the pulmonary arterial hypertension (PAH) animal model byarterial-vein shunting combining with injection of monocrotaline (MCT) and to observethe changes of small pulmonary vessels.METHODS: For establishment of the animal model, we divided60healthy male SD ratsinto4groups:①normal control group (n=15):The rats were given no treatment;②A-VFgroup (n=15): The rats were given an operation by shunting from abdominal aorta andinferior vena cava to establish the model of PAH;③MCT group:The rats were only givena single subcutaneous crotaline(50mg／kg);④A-VF+MCT group: The rats were injecteda single subcutaneous crotaline(50mg／kg) after the A-VF operation to make the model ofPAH.The mean pulmonary arterial pressure (mPAP), MA%,MT%,right ventricle index(RVHI) and the microstructure and remodeling changes of small pulmonary vessels weredetermined after4weeks.RESULTS:1. Compared with the normal control group,mPAP increased41%and76%separately in A-VF group and in MCT group. Morphological observation showed thatsmall pulmonary vessels’s mild or moderate stenosis and right ventricular mild ormoderate hypertrophy. Histology observation showed the endothelial cell’s mild necrosisand blood vessel’s mild fibrosis.2.It’s worth noting that the A-VF+MCT model weestablished for the fist time had more obvious changes. Compared with the A-VF groupand in MCT group,the mPAP, RVHI,MT%and MA%were significantly enhanced inA-VF+MCT group,meanwhile,the right ventriculus wall and pulmonary artery tunicamedia significantly thickened.CONCLUSION: The PAH rat model established through A-VF+MCT method is reliableand stable.The model could simulate the pathologic changes of severe PAH in human.Itwill lay the foundation for our follow-up research. Part II Umbilical cord blood mesenchymal stem cells transplantation in treatmentof pulmonary hypertension in ratsObjective:To observe the therapeutic effects of mesenchymal stem cells (MSCs) fromumbilical cord blood on pulmonary arterial hypertension in Sprague-Dawleye (SD) rats.METHODS: We divided60healthy male SD rats into4groups:①normal control group(n=15):The rats were given no treatment;②A-VF+MCT group (n=15): The rats weregiven a single subcutaneous crotaline(50mg／kg) after the A-VF operation to make themodel of PAH;③A-VF+MCT+MSCs group:5×106MSCs labeled with Hoechst33342were injected into the rats through tail vein4weeks after the shunting operation;④A-VF+MCT+DMEM/F12group: The rats were injected respectively a singlesubcutaneous cell culture medium4weeks after the shunting operation.The meanpulmonary arterial pressure (mPAP), right ventricle index (RVHI) and the microstructureand remodeling changes of small pulmonary vessels were determined4weeks after theMSCs transplantation.RESULTS: Compared with the normal control group,mPAP and RVHI weresignificantly enhanced after eight weeks in A-VF+MCT group,right ventriculus wall andpulmonary artery tunica media thickened more significantly The mPAP, RV/(LV+S),MT%and MA%decreased significantly in transplantation group compared toA-VF+MCT group(P<0.01). The mortality rate of PAH rats decreased from66.7%to13.3%. Fluorescence microscope showed that MSCs labeled with Hoechst33342werepermanently implanted in the tunica intima of the lung.CONCLUSION: MSCs transplantation can significantly reduce the pressure ofpulmonary artery, alleviate the pulmonary arterial remodeling, and lower the mortality rateof PAH rats.