Abstract.The aim of the current study was to confirm the effect and elucidate the mechanism of bone marrow mesenchymal stem cells (BMSCs) in acute myocardial infarction (AMI). AMI was induced in mini-swine by ligating the left anterior descending coronary artery, and BMSCs (1x10 7 ) were injected via a sterile microinjection into the ischemic area. Six months postoperatively, electrocardiograph-gated single photon emission computed tomography revealed that the myocardial filling defect was reduced and the left ventricular ejection fraction was improved in the BMSC group compared with the control group (P<0.05). Histopathological examination indicated that, in the BMSC treatment group, the percentage of survived myocardial tissue and the vessel density were increased, and the percentage of apoptosis was decreased compared with controls (P<0.05). Reverse transcription-polymerase chain reaction results indicated that the expression levels of multiple inflammatory factors were significantly upregulated in the BMSC group compared with levels in the control group (P<0.05). In conclusion, the present study demonstrated that BMSC injection significantly improved cardiac function and reduced infarct size in six months, indicating that this method may be valuable for future study in clinical trials.
IntroductionAccording to 2011 statistics, acute myocardial infarction (AMI) is one of the most prevalent causes of death and morbidity (1,2). Adult cardiomyocytes lack the capacity for regeneration, so scar tissue replaces lost myocardium following myocardial infarction, and this leads to cardiac remodeling with reduced left ventricular (LV) function (3). Cell therapy is a potential method for the regeneration and repair of myocardium and the improvement of myocardial function following ischemic injury (4). A number of cell types, including foetal Flk1 + CD34 + CD31 -bone marrow stem cells (BMSCs) have demonstrated cardiac regenerative capacity (5), however, the mechanism that stem cell transplantation utilizes in order to improve cardiac function following ischemic heart disease is unclear and there is little information available regarding the medium-and long-term effects. On the other hand, there exist a variety of transplantation methods, including local intramyocardial injection, intravenous injection, and intracoronary injection to the infarct zone (6). Intramyocardial injection of BMSCs has been demonstrated to be safe, and to lead to reverse remodeling and improved contractile ability of scarred areas (3,7). The mechanisms by which BMSCs reduce infarct size and improve cardiac function in animal models are complicated, involving engraftment, differentiation into functional cardiomyocytes and paracrine signaling (8,9). In the present study, fetal Flk1 + CD34 + CD31 -BMSCs were transplanted via intramyocardial injection of the mini-swine, then the myocardial function, stem cell migration and extent of survival in the myocardium was evaluated. The current study was therefore designed to determine the long-term (6-month) e...