OBJECTIVETo explore the effects of lentiviral-mediated CXC chemokine receptor-4（CXCR-4）gene over-expression on the homing capacity of mesenchymal stem cells（MSC）in vivo.

METHODSThe MSC overexpressing CXCR-4 were constructed by using the lentiviral vector-mediated mouse MSC overexpressing the CXCR-4 gene. The BALB/c mice were divided into 3 group: simple radiation group（TBI）in which mice exposed to total body irradiation, then were infused with normal saline; EGFP-MSC group in which mice were infused with MSC（5×10）transducted by EGFP via tail vein after TBI; and CXCR-4-MSC group in which mice were infused with MSC (5×10) simultaneously carraying EGFP and CXCR-4 gene via tail vein after TBI. The mice were sacrified at 24 hours after infusion, the frozen sections were prepared to detect the distribution of infused MSC. Furthermore, the numbers of MSC homing into spleen and bone marrow was detected by flow cytometry, and the level of stromal cell-derived factor-1(SDF-1) was detected by ELISA.

RESULTSThe frozen section showed that the CXCR-4 over-expression could significantly enhance the efficacy of MSC homing into lung, liver and spleen; the flow cytonetry detection slowed that the number of over-expressed CXCR-4 MSC homing into spleen and bone matrow was sigmificantly higher than that in EGFP-MSC group（P<0.05）, the ELISA showed that the SDF-1 level in peripheral blood and bone marrow after 24 hours of irradiation significantly incrtaoed （P<0.05）, moreover, the SDF-1 level increase was associcted with horming efficacy of MSC with CXCR-4 overexpression.

CONCLUSIONoverexpression CXCR-4 gene mediated by lentiviral vector can prmote the efficacy of MSC homing into spleen and bone marrow.