Recovery of Infarcted Myocardium in an In Vivo Experiment

Acute myocardial infarction leads to the loss of functional cardiomyocytes and structural integrity. The adult heart cannot repair the damaged tissue due to inability of mature cardiomyocytes to divide and lack of stem cells. The aim of this study was to evaluate the efficiency of introduced autologous skeletal musclederived stem cells to recover the function of acutely infarcted rabbit heart in the early postoperative period.
Material and Methods. As a model for myocardium restoration in vivo, experimental rabbit heart infarct was used. Autologic adult myogenic stem cells were isolated from skeletal muscle and propagated in culture. Before transplantation, the cells were labeled with 4´,6-diamidino-2-phenylindole and then, during heart surgery, introduced into the rabbit acutely infarcted myocardium. Postoperative cardiac function was monitored by recording electrocardiograms and echocardiograms. At the end of the experiment, the efficiency of cell integration was evaluated histologically.
Results. Rabbit cardiac function recovered after 1 month after the induction of experimental infarction both in the control and experimental groups. Therefore, the first month after the infarction was the most significant for the assessment of cell transplantation efficacy. Transplanted cell integration into infarcted myocardium was time- and individual-dependent. Evaluation of changes in left ventricular ejection fraction after the induction of myocardial infarction revealed better recovery in the experimental group; however, the difference among animals in the experimental and control groups varied and was not significant.
Conclusions. Autologous myogenic stem cells repopulated infarcted myocardium with different efficiency in each individual. This variability may account for the observed difference in postoperative cardiac recovery in a rabbit model.