Improvement of left ventricle remodeling by transplanting various autologous bone marrow stem cells / 中国组织工程研究

ABSTRACT

BACKGROUND:Bone marrow stem cell transplantation can improve heart function and prevent ventricle remodeling.At present,the adult bone marrow stem cells used for transplantation primarily included bone marrow mononuclear cells (BM-MNCs) and mesenchymal stem cells (MSCs),and endothelial progenitor cells.The curative effects and precise mechanisms of transplantation of various bone marrow stem cells remain unknown.OBJECTIVE:To compare the effects of transplantation of autologous BM-MNCs and MSCs via the coronary artery on ventricle remodeling subsequent to acute myocardial infarction (AMI). DESIGN,TIME AND SETTING:Randomized controlled animal experiment performed at the Center for Clinical Research,Hebei Provincial People's Hospital,Electron Microscope Room,Hebei Medical University between March 2005 and December 2006.MATERIALS:Thirty-six male Jizhong pigs,were randomly divided into 4 groups:control group (n = 6),infarct model group (n = 10),BM-MNC group (n = 10),and MSC group (n = 10).METHODS:Porcine autologous BM-MNCs were isolated by gradient density centrifugation,and MSCs were obtained by adherence method.Prior to transplantation,both BM-MNCs and MSCs were colloidal gold labeled.Except the infract model group,pigs in the other 3 groups were developed into AMI models by oppressing the left anterior descending branch with balloon catheter.Ninety minutes after modeling,(6.0±1.3)×107 autologous BM-MNCs and (4.5±2.1)x 107 MSCs were respectively transplanted into pigs in the BM-MNC group and the MSC group via the coronary artery and cultured for 28 days.MAIN OUTCOME MEASURES:Observation of pathological changes of cardiac muscle tissue by light and electron microscope;Examination of cardiac function by ultrasonograph;Detection of the number of blood vessels and apoptotic myocardial cells,and expression of nuclear factor-κB (NF-κB) and troponin Ⅰ and its correlation to cardiac function by immunohistochemistry;Detection of mRNA expression of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in the cardiac tissue as well as its correlation to cardiac function by reverse transcription-polymerase chain reaction (RT-PCR).RESULTS:In the MSC group,there was proliferation of a great deal of blood vessels as well as growth of abnormal cell masses around the coronary vessels,while the BM-MNC group exhibited the "budding" of many capillary vessels.Prior to transplantation,cardiac function indices were basically similar among each group (F = 1.550,P＞0.05).Twenty-eight days after transplantation,left ventricular ejection fraction was significantly lower in the control,BM-MNC,and MSC groups than in the infarct model group (F = 5.30,P＜0.05),while endocardial fractional shortening was significantly higher (F = 10.67,P＜0.01).Compared with the infarct model group,the number of blood vessels in the infarct zone and infarct border zone was increased in the BM-MNC group (F=29.56-34.87,P＜0.01) and had no apparent change in the MSC group.In the BM-MNC and MSC groups,apoptotic myocardial cells in the infarct zone and infarct border zone were significantly reduced (F=14.31-35.34,P＜0.01 ) and troponin I expression rate was significantly increased (F=19.05,P＜0.01 ),as compared with the infarct model group.In addition,NF-κB positive rate in the infarct border zone was significantly lower in the BM-MNC and MSC groups than in the infarct model group (F=19.05,P＜0.01).VEGF gene expression level in the infarct border zone was significandy higher in the BM-MNC group than in the infarct model group and MSC group (F = 49.41,P＜0.01).bFGF gene expression level in the infarct border zone was significantly higher in the MSC group than in the infarct model and BM-MNC groups (F=4.71,P＜0.01).LVEF was negatively correlated to myocardial cell apoptosis rate and NF-κB level (r=-0.441 1,P＜0.05;r=-0.579 6,P＜0.01 ).LVEF was positively correlated to number of blood vessels,VEGF and bFGF expression (r=0.775,P＜0.01;r=0.565 1,P＜0.05;r=0.573 5,P＜0.05).CONCLUSION:Transplantation of both autologous BM-MNC and MSC via coronary artery can improve the condition of left ventricular remodeling subsequent to myocardial infarction.The improvement of cardiac functions is related to the increase of blood vessels,VEGF and bFGF expression,the decrease of myocardial cell apoptosis and NF-κ B level in cardiac muscle tissues after stem cell transplantation.BM-MNC transplantation better promotes blood vessel proliferation and VEGF expression in the cardiac tissue but produces worse effects on bFGF gene expression than MSC transplantation.