Culture Assay for Murine Hemopoietic Precursor Cells. Bone marrow cells were obtained from femurs of SCH:

The effects of cis-diamminedichloroplatinum (NSC I 19875)on murine and human hemopoietic precursor cells were studied in culture. When murine cells from normal and actively regenerating marrows were exposed to cis diamminedichloroplatinum in culture, washed free of the agent, and assayed for the surviving hemopoietic precursor cells, similar sensitivity curves were obtained. This result indicates the absence of cell-cycle dependency of cis-diam minedichloroplatinum. When marrow cells were exposed to cis-diamminedichloroplatinum inculture at various temper atures, only minimal reduction of cytotoxicity was noted at 4°.This observation, unlike that from the experiment with nitrogen mustard, suggests that the transport ofthis agent is by passive diffusion. Finally, when the sensitivity of human hemopoietic precursor cells to this agent was assessed using similar conditions and compared to that of murine hemo poietic precursor cells, a significant species difference was observed.