OBJECTIVETo evaluate the therapeutic potential of marrow-derived cardiac stem cell (MCSC) transplantation after myocardial infarction (MI) in rats.

METHODSMCSC were selected from the marrow mesenchymal stem cell (MMSC) of male SD rats by single-cell cloning culture. MI was induced by left anterior descending artery ligating in female SD rats. Equal volume PBS, MMSC and MCSC were transplanted at the border zone of the infarct one week after MI. Cardiac function was assessed by echocardiography at four weeks after cell transplantation. The hearts were removed and morphological changes of scar tissue were examined with HE staining and Masson trichrome staining, VEGFR-1(+) capillary vessels were labeled with immunohistochemical staining. Scar area and vessel density were measured by image analyzer. MCSC containing Y chromosome were examined using in situ fluorescent hybridization, and cardiomyocyte cTnT expression was also analyzed.

RESULTSCardiac transcription factor Nkx2.5 was expressed at low level in c-kit(+) MCSC. Four weeks after cell transplantation, left ventricular fractional shortening and ejection fraction were significantly higher while scar area was significantly lower in MCSC group compared to MMSC group and control group. cTnT was expressed in cells containing Y chromosome and these cells were connected with myocardium of recipient rats in the rats transplanted with MCSC. Vessel density around the infarcted tissue in MCSC group was similar as that in MMSC group and significantly higher than that in control group.

CONCLUSIONMSCS could effectually differentiate into functional cardiomyocytes at the border zone of the infarct, and MCSC transplantation post MI significantly improved cardiac functions and promoted angiogenesis.