title: Effects of rhG-CSF, 5-fluorouracil and extramedullary irradiation on murine megakaryocytopoiesis in vivo.
abstract: The aim of this study was to systematically characterize possible rhG-CSF effects on the murine megakaryocyte-platelet system (untreated and recovering from chemotherapy or extramedullary irradiation). In untreated, splenectomized male B6D2F1 mice, rhG-CSF treatment (50 micrograms/kg/d for up to 8 d) markedly decreased femoral megakaryocytopoiesis. CFU-Meg, small acetylcholinesterase-positive (SAChE) cells, and megakaryocytes were significantly reduced to 35-70%; platelets, however, were not affected. Peripheral CFU-Meg and CFU-GM increased up to 200-fold. Following a single injection of 5-FU (150 mg/kg) on day 0, rhG-CSF (50 micrograms/kg/d) on days 1-8 suppressed the megakaryocytopoietic recovery as indicated by significantly lower platelet numbers on day 9. Granulopoietic recovery was accelerated by rhG-CSF. When rhG-CSF treatment was started on day 5, no beneficial effect on granulopoietic recovery was observed, but again platelet levels were significantly lower on day 9, indicating that within the first 4 d of rhG-CSF application, recruitment or lineage competition was not a critical event. To test for the effects of extramedullary irradiation on circulating progenitors, mice pretreated with 50 micrograms/kg/d of rhG-CSF for 8 d received irradiation to the chest with 500 cGy resulting in a substantial kill of circulating CFU-Meg and CFU-GM of up to 99%. However, this striking decrease of blood progenitors did not significantly affect their total body contents. This study indicates that rhG-CSF treatment can impair bone marrow megakaryocytopoiesis, which might be an important consideration for those clinical situations that carry a high potential for treatment-induced thrombocytopenia.
authors.affiliation: Division of Hematology and Oncology, Wayne State University, School of Medicine, Detroit, Michigan 48201.
authors.forename: S
authors.initials: S
authors.lastname: Scheding
authors.forename: J E
authors.initials: JE
authors.lastname: Media
authors.forename: M
authors.initials: M
authors.lastname: Kraut
authors.forename: M
authors.initials: M
authors.lastname: Valdivieso
authors.forename: A
authors.initials: A
authors.lastname: Nakeff
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000528:radiation effects; D001854:Bone Marrow Cells; D005472:Fluorouracil / Q000494:pharmacology*; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D006098:Granulocytes / Q000187:drug effects / Q000528:radiation effects; D006410:Hematopoiesis / Q000187:drug effects* / Q000528:radiation effects; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000528:radiation effects; D008297:Male; D008533:Megakaryocytes / Q000187:drug effects* / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D011994:Recombinant Proteins; D016179:Granulocyte Colony-Stimulating Factor; D005472:Fluorouracil