Effects of cis-diamminedichloroplatinum (II) upon haemopoietic progenitors and the haemopoietic microenvironment in mice.

We studied the short- and long-term effects of a fractionated injection of cis-diamminedichloroplatinum (II) (CDDP) upon the haemopoietic stroma and the haemopoietic precursor cell compartment of young and adult mice. The integrity of the stromal microenvironment was investigated using three different assays including quantification of (a) the fibroblastoid progenitor cell compartment, (b) the regenerative capacity after subcutaneous implantation of spleen and femur, and (c) the growth of normal bone marrow progenitors in lethally irradiated CDDP-treated mice. CDDP treatment induced a slight anaemia which lasted for the observation period of 1 year, and could not be restored by infusion of normal bone marrow cells. The population size of haemopoietic progenitors was severely decreased immediately after CDDP treatment and the CFU-S recovery in the bone marrow was slow and temporary. Stromal function was significantly decreased and normalization occurred within approximately 40 d, depending on the stromal parameter measured. Subsequently, the regenerative capacity of the stroma showed a second decrease which was still detected at 1 year. This pattern of stromal damage has not been reported for any other cystostatic agent. Since the other two assays did not detect a second decrement in stromal integrity it is implied that the three stromal assays used detect different stromal functions. We conclude that CDDP treatment of both young and adult mice results in severe short-term damage and a late occurring secondary regenerative defect of the haemopoietic organ stroma.