Stromal cell-derived factor-1 (SDF-1) and its CXCR4 receptor have been reported to play several roles in mobilization of bone marrow stem cells to the injured heart, cell migration and apoptosis in certain hematopoietic and neuronal cells and neoangiogenesis in cancer cells. Mesenchymal stem cells (MSCs) isolated from adult bone marrow is the important source for cell transplantation in infarcted myocardium. Here we show that SDF-1 promotes the survival and growth of MSCs derived from mouse bone marrow. MSCs isolated from bone marrow of ICR (6 to 8-wk-old) mice were cultured for 7 days in vitro to deplete hematopoietic lineage cells. Sca-1+ MSCs were purified by magnetic-activated cell sorting system and exposed to 0.2 mM H₂O₂ in the absence or presence of 100 ng/ml SDF-1 in order to examine whether SDF-1 confers direct protective effects on MSCs. The phenotype characteristics, multipotentiality, early apoptotic index (annexin-V+), necrosis (propidium iodide staining) and cell growth curve of Sca-l+ MSCs were analyzed. Flow cytometry showed that 9.2% of Sca-1+ MSCs expressed CD45, and <2.0% of the cells expressed CD34 and c-kit. Sca-1+ MSCs differentiated into adipocytes or osteocytes after treatment with specific induction medium for 3 weeks in vitro, confirmed by Oil Red O and Alizarin Red S staining, respectively. Co-incubation with SDF-1 significantly reduced the number of H₂O₂-induced annexin V-positive cells compared with cells that were not given the SDF-1 (18.14 짹 7.56 % versus 29.67 짹 66 %, P <0.05). When Sca-1+ MSCs (1.25 x 10⁴ cells) were cultured in the presence of 100 ng/ml SDF-1 for 3 days, the cell growth was increased than untreated control (7.8 x 10⁶ 짹 3.2 x 10⁵ cells versus 6.0 x 10⁶ 짹 2.7 x 10⁵ cells). Cell necrosis was not affected by SDF-1 treatment. These results suggest that SDF-1/CXCR4 signaling stimulates anti-apoptotic pathways in infarcted myocardium. The transplantation of MSCs transfected with SDF-1 for myocardial regeneration will promote the survival of transplanted MSCs as well as the mobilization of stem cells from bone marrow.