Expression of CXCR4 in cord blood-derived CD133+cells treated with platelet micro-particles

Platelet micro-particles (MPs) contain CXCR4 markers and are able to transfer them into hematopoietic stem cells. Therefore, effect of platelet MPs (PMPs) on the expression levels of CXCR4 and CD34 markers in these cells was examined. Isolated CD 133+ cells cultivated for 5 d in the stem span medium and PMPs. Fold increase of CD34+ cells in the presence of 5 and 10 g/ml of PMPs was increased significantly. CXCR4+ cell percent in the presence of 10 g/ml PMPs compared with control cells (63.8 +/- 6.4) was increased (P < 0.05). PMPs were no affect on clonogenicity of hematopoietic progenitor cells. Background: Cord blood CD133+ cells are able to maintain long-term hematopoiesis and to differentiate to hematopoietic lineages. CXCR4 over expression is involved in homing and successful transplantation of hematopoietic stem cells (HSCs) in the bone marrow. PMPs contain CXCR4 markers and are able to transfer them into hematopoietic stem cells. Therefore, considering the importance of CD133+ cells as primitive HSCs, the effect of PMPs on the expression levels of CXCR4 and CD34 markers in these cells was examined. Materials and methods: Cord blood CD133+ cells were isolated by MACS. Isolated cells were divided into three groups: (i) control cells, (ii) cells treated with 5 mu g/ml PMPs, (iii) cells treated with 10 mu g/ml PMPs. Cells were cultivated for 5 d in the stem span medium. Expression of CD 133, CD34, and CXCR4 surface marker was analyzed by flow cytometry. Total cell numbers were counted by hemocytometer and clonogenicity were measured by colony assay. Results: PMPs were no effect on CD133+ cells proliferation, but fold increase of CD34+ cells in the presence of 5 and 10 g/ml of PMPs was increased significantly. CXCR4+ cell percent in the presence of 10 g/ml PMPs compared with control cells (63.8 +/- 6.4) was increased (P < 0.05). PMPs were no affect on clonogenicity of hematopoietic progenitor cells. Conclusions: Exposure of CD133+ cells isolated from cord blood to PMPs with 10 mu g/ml concentration increased the expression of CXCR4 surface marker significantly.