title: Radioprotective effects of (-)-epigallocatechin-3-gallate on human erythrocyte/granulocyte lineages.
abstract: Epigallocatechin-3-gallate (EGCg) is widely recognised as a powerful antioxidant and free radical scavenger. This study examined the radioprotective effects of EGCg on human granulopoiesis and erythropoiesis. Highly purified human CD34(+) haematopoietic stem/progenitor cells were prepared from human placental/umbilical cord blood. The cells were exposed to X rays at a dose rate of ∼1 Gy min(-1) and then cultured in a medium supplemented with either granulocyte colony-stimulating factor (G-CSF) or erythropoietin (EPO). EGCg (100 nM) was added to the culture immediately before or after X-irradiation. The concentration of 100-nM EGCg was determined in the authors' previous study. The number of granulocyte and erythrocyte colonies generated by X-irradiated CD34(+) cells decreased in a dose-dependent manner. Although EGCg addition yielded an ∼2-fold increase in the proliferation of each haematopoietic progenitor, no significant protective effect was observed in the surviving fraction of granulocyte progenitors (G-CSF alone: D(0)=1.06 Gy, n=1.14). However, EGCg addition before or after irradiation conferred a significantly higher protective effect on erythrocyte colony formation compared with the control (EPO alone: D(0)=0.66 Gy, n=1.56; EGCg (before): D(0)=0.43 Gy, n=5.48). EGCg addition before irradiation significantly improved the survival of erythroid progenitors subjected to radiation of <1 Gy. These results suggest that EGCg is more protective of erythropoiesis than granulopoiesis from radiation damage.
authors.affiliation: Department of Radiological Life Sciences,  Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki, Aomori 036-8564,  Japan.
authors.forename: S
authors.initials: S
authors.lastname: Monzen
authors.forename: I
authors.initials: I
authors.lastname: Kashiwakura
mesh_terms: D018952:Antigens, CD34 / Q000096:biosynthesis; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D019070:Cell Lineage; D004912:Erythrocytes / Q000528:radiation effects*; D004921:Erythropoietin / Q000378:metabolism; D005260:Female; D016179:Granulocyte Colony-Stimulating Factor / Q000378:metabolism; D006098:Granulocytes / Q000528:radiation effects*; D006412:Hematopoietic Stem Cells / Q000528:radiation effects; D006801:Humans; D010920:Placenta / Q000528:radiation effects; D011247:Pregnancy; D011837:Radiation-Protective Agents / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000378:metabolism; D013234:Stem Cells / Q000528:radiation effects; D014470:Umbilical Cord / Q000528:radiation effects; D014965:X-Rays
chemical_list: D018952:Antigens, CD34; D011837:Radiation-Protective Agents; D011994:Recombinant Proteins; D004921:Erythropoietin; D016179:Granulocyte Colony-Stimulating Factor; D002392:Catechin; C045651:epigallocatechin gallate