抄録
Epigallocatechin gallate (EGCg) has been known to be a powerful anti-oxidant and a radical scavenger. However, its role of proliferation and radioprotection has remained to be unclear. Therefore, we investigated that the effects of EGCg on megakaryocyte progenitor cells which carried out radiation exposure using CD34+ cells prepared from the human placental and umbilical cord blood.
The colony forming unit-megakaryocyte (CFU-Meg) were assayed with thrombopoietin (TPO) alone or together with EGCg by plasma clot technique using platelet poor human plasma. EGCg showed the dose-dependent efficacy of increasing the CFU-Meg number up to 100 nM. EGCg stimulated a 1.5-fold increase in the total CFU-Meg number compared with the control. In the culture of 2 Gy-irradiated CD34+ cells, the similar increasing effect was observed by the addition of EGCg. Especially, its radioprotective effect is shown at a relative low dose (0.5 - 2 Gy) from the radiation survival curve.
Non-irradiated and X-irradiated (2 Gy) CD34+ cells were cultured in liquid culture medium contained with TPO alone or TPO plus EGCg for 14 days. The combination of TPO plus EGCg resulted in increase in the CFU-Meg number in the both of 0 Gy and 2 Gy.
These results suggest that EGCg shows the radioprotective effect on the growth of CFU-Meg at low dose of X-irradiation, and it is possible to use as one of radioprotective agents.
