OBJECTIVETo investigate the effects of platelet factor 4 (PF4) on the adherence, and the expressions of adherent molecules CD(49d) and CXCR4 and the receptor of SDF-1 of fresh and expanded cord blood CD(34)(+) cells.

METHODSCD(34)(+) cells were isolated from cord blood using MACS immune magnetic beads. The adherent ability was assayed by using crystal violet staining and the expression of adherent molecule CD(49d) and CXCR4 by FACS.

RESULTS(1) PF4 could increase the adherent ability of the fresh cord blood CD(34)(+) cells, the effect being positively correlated with the dose of PF4. (2) SDF-1 at concentration of 100 ng/ml increased the adherent ability of the fresh cord blood CD(34)(+) cells. (3) The spontaneous and the SDF-1 induced adherent ability of the cord blood CD(34)(+) cells began to decrease after being cultured for 10 days without PF4, while in the presence of PF4 at 100 ng/ml, the ability of the cord blood CD(34)(+) cell adhering to the stroma layer still remained at higher level. At day 14, the adherent ability was (262.04 +/- 64.81)% and (64.35 +/- 8.29)% in PF4 group and control group, respectively, if it was defined as 100% at day 0. SDF-1 at concentration of 100 ng/ml induced adherent ability was (138.31 +/- 32.39)% and (67.66 +/- 12.44)% in PF4 group and control group, respectively. (4) The expression of CD(49d) and CXCR4 increased 13.02% and 17.33%, respectively, when incubated with PF4.

CONCLUSIONSPF4 could increase the adherent ability and promote the expression of CD(49d) and CXCR4 of the cord blood CD(34)(+) cells, suggesting that PF4 promote the circulating stem cells homing to the marrow in the process of stem cells transplantation.