Protective effects of platelet factor 4 on bone marrow stromal cells of acute radiation injury in mice

AIM: To investigate the protective effects of platelet factor 4 (PF4) on bone marrow stromal cells (BMSCs) of radiated mice and to study the protective mechanism of hematopoietic radiation injury in mice. METHODS: Forty male mice were randomized to four groups (R, R+P, N+P and N) and two of groups (R, R+P) were exposed whole-bodily to 5.0 Gy ()~(60)Co γ-rays. The mice were treated with injections of PF4 (50μg/ kg), ip twice at an interval of 6 h and 20 h. After the second injection, they were irradiated. The cell cycle and apoptosis of bone marrow stromal cells (BMSCs) cultured in vitro after radiation were analyzed by FACS after ten days' culture. The expression of p27~(kip1) in the cells was detected using immunohistochemistry. RESULTS: The 24th hour adhesion rate of BMSC in radiated mice respectively reached 37%, 58%, 74% and 79.3%. The cell percentage of G0+G1 phase increased and those of G2+M decreased in R group, compared with those in R+P, N+P and N groups. But the DNA content of the radiated group of BMSC decreased remarkably compared with those in the other three groups. The expression of p27~(kip1) was down-regulated compared with that of BMSC without PF4 protection. CONCLUSION: The protective effects of PF4 on BMSCs with radiated injury probably result from the inhibition of the expression of p27~(kip1).