OBJECTIVETo search for the bone mesenchymal stem cell (MSC) subgroup which might be more effective on repairing myocardial damage.

METHODSIn this experiment, four MSC subgroups were defined based on the surface differentiation antigen detection of mouse bone mesenchymal stem cells (mBMSCs): SCA-1(+)/CD45(+)/CD31(+), SCA-1(+)/CD45(+)/CD31(-), SCA-1(+)/CD45(-)/CD31(-) and SCA-1(+)/CD45(-)/CD31(+). These subgroup cells and unselected mBMSCs were injected into infarcted mouse via tail vein. Echocardiographic heart function measurement and in vivo DiR-labeled stem cells imaging were performed at 48 h after injection. In situ C-kit (a flag antigen of cardiac stem cells) and cardiac-specific differentiation antigen immunohistochemistry detection was made in the infarcted myocardium.

RESULTSThe capacity of the SCA-1(+)/CD45(+)/CD31(+) cells on improving heart function was significantly higher than other cell groups (all P < 0.05). In vivo imaging showed that the mean fluorescence intensity of the SCA-1(+)/CD45(+)/CD31(+) cells was also higher than other cell groups (all P < 0.05). Number of cardiac stem cells in the infracted myocardium was significantly increased after the injection of all subgroup cells and unsorted mBMSCs cells for 48 h compared untreated infracted myocardium. The capacity of mobilizing cardiac stem cells is as follows: SCA-1(+)/CD45(+)/CD31(+) >SCA-1(+)/CD45(-)/CD31(+) >SCA-1(+)/CD45(-)/CD31(-) >SCA-1(+)/CD45(+)/CD31(-).

CONCLUSIONThe SCA-1(+)/CD45(+)/CD31(+) subgroups of mBMSCs exhibites the highest capacity to improve cardiac function after myocardial infarction and to mobilize autologous cardiac stem cells compared with other mBMSCs subgroups and unsorted mBMSCs cells.