Abstract
In a previous study, we have demonstrated that in the radio-sensitive megakaryocyte progenitor cells, namely colony-forming unit megakaryocytes (CFU-Meg), the degree of X-ray-induced damages was prevented by the post-treatment with several cytokines. On the other hand, heavy ion particles provide unique properties in radiotherapy. However, they have also been shown to pose high risks for both accident victims and astronauts participating in space missions. We therefore analyzed that the effects of cytokines on heavy ion particles-irradiated CFU-Meg.
The CD34+ CFU-Meg were isolated from the human placental/umbilical cord blood using a magnetic isolation kit and then were exposed to a carbon ion beam (LET=50 KeV/micro m). The number of CFU-Meg were calculated by a plasma clot technique. The differentiation to megakaryocytes and the release of platelets and the increase of gamma-H2AX, a marker of DNA double-strand breaks (DSBs), were both analyzed by flow cytometry.
The sensitivity to carbon ion beam was found to be extremely much high and it could not be lowered by any type of cytokine combination unlike X-rays. However, a treatment with thrombopoietin and interleukin-3 potentially induced megakaryocytepoiesis at 14 days after the exposure of a carbon ion beam at 2 Gy. The induction of gamma-H2AX by carbon ion beam irradiation in CD34+ cells was not influenced by cytokine treatment. These results showed that the repair of DSBs by cytokine was therefore less strongly promoted in the progenitors to carbon ion beam than in X-rays.
