Studies on the impairment of bone marrow cells by chemotherapeutic agents

DNA synthesizing ability of the bone marrow cells in vitro could be determined with precursor of both 14C-formate through de novo synthesis system and 3H-thymidine through salvage system, however, the experimental results revealed the predominance of salvage system in the DNA synthesizing system. The effects of MMC to the DNA synthesis of the bone marrow cells in vitro were examined by 14C-formate and 3H-thymidine as precursor, and the both measurements showed almost the same dose response curve. VLB inhibited the DNA synthesis of the bone marrow cells in vitro than VCR did, which coinsided to the clinical results that VLB induced remarkable reduction of the leukocytes that VCR did. The effects of 5-FU which inhibited the DNA synthesis of the bone marrow cells during proliferating stage were studied by colony forming units in spleen, and the results revealed slight hazards of the hematopoietic cells. This fact explained the unremarkable reduction of the leucocytes in clinical cases. (Mukohata, S.)