| Objective:Previous studies reported transplantation of bone marrow stem cells was safe and feasible for AMI.However,little was known about differention and the role about bone marrow mesenchymal stem cells(BMSCs)in repairing of infracted myocardium fwith AMI.As a result,the present study aimed at resolving several issues including:1)Setting-up a swine model of acute myocardial infarction(AMI)by coronary occlusion with angioplasty balloon.Then observe the cardiac size and cardiac function change before and after bone marrow cells transplantion.2)To establish the methods for isolation and culture of BMSCs.3)To investigate the feasibility of in vivo tracking for mesenchymal stem cell delivered to infracted myocardium by MRI.4)To observe the cardiac size and cardiac function change before and after mononuclear bone marrow cells transplantion in patients with actue anterior myocardial infarction by echocardiography. Methods:1)Firstly,left anterior desending coronary artery of ten pigs which 3 to 5 months age and 25 kg to 40kg weight was blocked for 60 mins by the balloon to induce the acute myocardial infarction.Then the animals were divided into two groups randomly. In the study group,80ml marrow was aspirated and MSCs were islolated and cultured in vitro then were transplantated into AMI area two weeks later.While 0.9%sodium was injected in the same way in the control group.The implantated cells and cardiac special proteins such as GATA-4 were examined by cellular immunochemical stain after 4 weeks. Echocardiography was performed to observe the changes of cardiac function before and after transplantation.2)8 pigs,weight 35～45 kg.The acute myocardial infarction(AMI) model was set up by occlution anterior descending coronary artery with balloon.Then the animals were divided into two groups randomly.The in study group,the bone marrow mesenchymal stem cells were labeled by surpurparamagnetic iron oxide nanoparticles (SPIO)were injected into myocardium of 4 pigs while stem cells without labeling were injected in to 3 pigs.The heart was checked by MRI before transplant,one hour,two week and four weeks after transplant.The pigs were sacrificed for histological examination and Prussian blue stain two weeks post MI. CD44 and CD106 were examined by Flow cytometry for different cell generaion.3) Eight patients with acute anterior myocardial infarction were enrolled for cell transplantation.All patients were given standard drug and percutaneous coronary intervention(PCI)therapy.Mononuclear bone marrow cells were transplanted via over-the-wire(OTW)ballon after PCI.All patients were followed up by echocardiography,ECG.and 99mTc-MIBI myocardial SPECT to make sure the safety. Results:1)Nine animals set up the acute myocardial infarction model successfully.The mesenchymal stem cells were transplanted successfully at 5 pigs.After cell transplantation,the beneficial effects on cardiac function were obvious in the study group for LVEF increased from(60.0±3.8)%to(66.4±6.1),P＜0.05.At the same time,IWMVs increased from(7.4±0.4)cm s-1to(8.0±0.3)cm s-1,P＜0.05.The study group had better LV ejection fraction and infarction wall movement velocity than the control group,(66.4±6.1 VS 54.0±1.4,t=3.926,P＜0.05)and(8.0±0.3 VS 6.9±0.2,t=6.315,P＜0.05).All the hearts of MSCs transplanted pigs were found that new generated myocardiocytes existed aroud ischemic and infracted zone and the Desmin protein,Connexin 43 and GATA- 4 were expressed positively.2)MRI show the defect in apex and delayed intensity in seven pigs making sure the setting up of the acute myocardial infarction(AMI)model was successfully.Injection sites in group injected with SPIO labeled stem cells can be tracked by MRI in all 4 animals after one hour of transplant and in 3 animals after four weeks of transplantation.Prussian blue stain is positive in the injection sites of the group that injected with SPIO labeled stem cells.SPIO can adherent to MSCs membrane after 24 h culture.There were some blue-green particles in the labeled cells and cell nucleus was red after Prussian blue staining.The labeled cells morphology and viability did unchanged. SPIO can be found on the membrane of MSC by the scanning electron microscope.3)All patients underwent mononuclear bone marrow cells successfully.No significant differen-ce was found of LVEF before and after the cell transplantation.The number of myocar-dial segments with reversible or irreversible perfusion defects decreased in patients compared with pretransplantation.No one suffered palpitation,remycardiol infarction or heart failure during the follow up.Conclusion:1)Swine model of acute myocardial infarction can be set up successfully by coronary occlusion with angioplasty balloon.2) Self transplantation of MSCs induced new generated cardiac cells in hearts of acute myocardial infarction pigs and therapeutic effectiveness in improving cardiac function.3) The Connexin-43 and GATA-4 positive cell can be found in the transplanted area with histological examination that is a sign of servival of MSC.4)In vivo tracking SPIO labeled stem cells by MRI can be an effectively and feasible way.5)SPIO did not affect viability and morphology of MSCs,but can adherent to MSCs effectively.6) Mononuclear bone marrow cells transplantion can release the enlargement of left ventricular and keep cardiac function of patients with actue anterior myocardial infarction. There are not remycardiol infarction and heart failure during the middle term follow up.
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