The Dynamic Change Of Stem Cells In Heart Tissues Induced By Acute Myocardial Infarction

Background In recent years,stem cell transplantation for the treatment of myocardial infarction has become a major research hotspot.Mobilization of myocardium into the stem cell regeneration and repair has become the focus of the current debate and research direction,but also determines the future stem cell treatment of heart disease diversity.At present,there are Sca-1 positive myocardium stem cells,c-kit positive myocardium stem cells and Nanog positive myocardium stem cells.They have the potential to differentiate into cardiomyocytes.But after myocardial infarction,how does the dynamic changes in myocardial stem cells? How are their co-expression in cells? These issues need to be further studied.Objective To investigate the dynamic changes of myocardial stem cells at different time points after acute myocardial infarction in rats and the co-express of its markers.Methods Twenty-five healthy adult SD rats were randomly divided into normal control group(n = 5)and acute myocardial infarction group(n = 20).The left ventricular ejection fraction(EF),left ventricular short axis shortening(FS),left ventricular diastolic dilatation(left ventricular)were measured before and 1 w,2w,3w and 4w after operation.(LVID;d),left ventricular end-diastolic volume(LV Vol;d)and left ventricular end-diastolic posterior wall thickness(LVPW;d).Immunohistochemical technique was used to observe the dynamic changes and count of sca-1 positive myocardium stem cells.The coexpression of sca-1,c-kit and nanog was observed by immunofluorescence double labeling technique.Western Blotting was used to detect the expression levels of c-kit,nanog and sca-1 protein.Results1 The levels of EF,FS and LVPW in the model group were decreased(P <0.05).LVID;d,LV Vol;d increased gradually(P <0.05).2 Immunohistochemical results showed that the number of myocardium nanog,c-kit and sca-1 positive myocardium stem cells increased to the peak at 2w,then decreased.In the early stage of infarction positive cells scattered expression,3w in the infarct area gathered into a group or strip.3 Immunofluorescence results showed that there were co-expression between the nanog and c-kit proteins,sca-1 and c-kit proteins,sca-1 and nanog proteins in the infarcted region.4 Western Blotting results showed that c-kit,nanog and sca-1 protein reached the peak at2 w,which was consistent with the results of immunohistochemistry.Conclusions1 Myocardial stem cells change with the change of infarct time,stem cells have a tendency to migrate to the infarcted area and aggregation.2 A stem cell can express two kinds of stem cell surface markers,suggesting that myocardial stem cell subsets may overlap,and the function may be diverse.