OBJECTIVETo investigate the effects of human umbilical cord blood-derived mesenchymal stem cells(HUCMSC) on the leukemic cell line HL-60 and acute lymphoblastic leukemia cell line Jurkat as well as the role of CXCL12/CXCR4.

METHODSHL-60 cells and Jurkat cells were co-cultured with human umbilical cord blood mesenchymal stem cell (HUCMSC), and the model was treated with G-CSF, AMD3100 and their combination. The cell viability and cell cycle were measured by Cell Counting Kit-8 (CCK-8), the apoptosis and the cell-cycle analysis were assessed by flow cytometry with the Annexin V/PI double staining. The expression of surface CXCR4 protein and total CXCR4 protein of leukemic cells were detected by flow cytometry and Western blot respectively.

RESULTSHUCMSC could decrease the viability of HL-60 cells and Jurkat cells, as well as the percentage of apoptotic cells, they could also increase the number of G/Gcells, while G-CSF and AMD3100 could reduce the proliferation of HL-60 cells and Jurkat cells in HUCMSC co-culture model, destructed the anti-apoptotic effect of HUCMSC on HL-60 cells and Jurkat cells, and the combination of 2 drugs resulted in a synergistic effect. The G-CSF could reduce the expression of surface CXCR4 protein and total CXCR4 protein in leukemic cells, while AMD3100 could only decrease the expression of surface CXCR4 protein of leukemia cell membrane, having no effect on the expression of CXCR4 protein in cytoplasm.

CONCLUSIONHuman umbilical cord blood mesenchymal stem cells can inhibit the proliferation and apoptosis of acute leukemia cells and increase the number of G/Gphase cells in leukemic cells. The AMD3100 can decrease the expression of surface CXCR4 protein in leukemia cells, G-CSF can decrease expression of total CXCR4 protein as well as membrane CXCR4 protein. Both of them can block the CXCL12/CXCR4 signal axis, weakening the relationship between leukemia cells and microenvironment. And on the basic of HUCMSC influenced leukemia cells' growth and proliferation, the cell viability will be weakened, its apoptosis will be promoted, and the percentage of G/Gphase cells in leukemia cells will be decreased.