A Pilot Study On PET Imaging Evaluation For Stem Cell Transplantation In A Rat Model Of Myocardial Infarction

Objective Myocardial infarction (MI) is one of the primary causes of mortality. Traditional therapeutic approaches may improve cardiac function but cannot repair infarct myocardium. Stem cell has the potential of differentiating into myocardium, which provides an alternative therapeutic approach for MI. The purpose of this study is to monitor and compare the therapeutic responses of induced pluripotent stem cell (iPSC) and embryonic stem cell (ESC) by small animal positron emission tomography (micro-PET) in a rat model of MI.Methods Male Sprague-Dawley rats were underwent left lateral thoracotomy. Rats were randomly divided into3groups:iPSC, ESC or phosphate-buffered saline (PBS) control group (n=7in each group). At30minutes after MI, a volume of150uL stem cell (2×106) or PBS was injected intramyocardially in five equal aliquots into the peri-infarct area. The treatment response was evaluated at Day3, Week1,2,3,4after stem cell transplantation by18F-FDG micro-PET. Postmortem immunohistochemical staining and autoradiograpnic imaging were performed after the last micro-PET.Results Compared with the PBS control group, significantly increased F-FDG accumulations was observed in the iPSC and ESC transplanted groups over the4-week study period (p<0.001and p<0.001, respectively). At Week1,18F-FDG accumulations in ESC group was significantly higher than that of the iPSC group (p= 0.029). At Week2,18F-FDG accumulations of iPSC group was higher than that of the ESC group (p=0.53). However, from Week3to4, significantly higher18F-FDG accumulations was found in iPSC group compared to that of ESC group (p<0.001). Autoradiographic imaging result was consistent with the last PET findings. Immunohistochemical staining demonstrated that transplanted stem cells survived in the injected sites and improved the myocardial function. Additionally, there was no teratoma formation within the study period.Conclusion Compared to ESC, iPSC seemed to be a better source of regenerative therapy for myocardial repair.18F-FDG PET imaging demonstrated significant metabolic and functional recovery after iPSC and ESC transplantation in the rat model of MI.