LPS-pretreated bone marrow stem cells as potential treatment for myocardial infraction

The purpose of this study is too investigate the distribution, the number, and the survival time of rat bone marrow mesenchymal stem cells (BMSCs), implanted in rats with myocardial infarction (MI), that were initially pretreated with low dose of LPS. Adult rats were randomly divided into control group, the MI group, 0.1, 1 and 5 mg/kg LPS-pretreated groups. Following the injection of CM-Dil labeled into the mid left anterior descending coronary artery ligation in the left ventricle wall, the number and survival time of red fluorescent labeled BMSCs were determined in the myocardial infarction 48h, 1, 3, and 4 weeks post-injection.. In addition, BMSC cell survival and apoptosis as well as the expression of associated proteins were also studied. After 1 week, the number of red fluorescent cells decreased significantly in MI group and 0.1mg/kg LPS groups, and the decrease was more obvious in 5mg/kg LPS group. However, a large number of BMSCs was apparent in 1mg/kg LPS group, the survival of positive cells was higher than MI group (P less than 0.05), part of the transplanted stem cells migrated into the injured area of the myocardial tissue, and in the injury centers more cardiac stem cells were grouped together. Following 3-4 weeks post-implantation of BMSCs, fluorescence almost disappeared in MI group , while it was still present and scattered in 1mg/kgLPS. Furthermore, while BMSCs showed low survival rate in the MI group, reduced apoptosis was observed in low-dose LPS groups.