An apparent discrepancy between the number of colony forming units transplanted and survival of busulphan lethally treated rats

Abstract

Conditions for keeping busulphan lethally treated rats alive by transplantation of bone marrow cells from syngeneic donors are described. After busulphan treatment of the donor rats with a dose which only reduces the colony forming units (CFU's) in the marrow (assayed by the spleen colony technique) to half the normal numbers, a t least 100 times as many cells from these treated donors, compared to untreated rats, are required to produce an equivalent increase in survival of busulphan lethally treated recipients. In contrast, aminochlorambucil, despite producing a marked fall in bone marrow cellularity, has no effect on the number of CFU/femur, yet the marrow from these aminochlorambucil treated donors is no more effective in increasing the survival of busulphan lethally treated recipients than untreated marrow. Theories which may explain this apparent discrepancy and evidence which it affords on the mode of action of busulphan are discussed.Many reports have appeared regarding the use of bone marrow cell grafts to overcome the lethal effects of radiation in the mouse. However, such bone marrow therapy has not achieved the same degree of success in the rat mainly because this species appears to be more susceptible to the intestinal tract effects of radiation. As a result, death frequently occurs within a few days of irradiation and few animals survive long enough to succumb to "bone marrow" death.Many cytotoxic chemicals, particularly those of the "nitrogen mustard type (Elson, '63) also cause death of rats from gastrointestinal toxicity against which bone marrow therapy is ineffective (Maisin, '61). However, with certain of the cytotoxic chemicals, particularly busulphan ( 1, 4-dimethanesulphonoxy-butane, "Myleran") and "di-methyl myleran" (1, 4-dimethyl dimethanesulphonoxy -butane), gastrointestinal death does not occur in rats with doses which lead to death of all the animals from bone marrow aplasia (Elson, Galton and Till, '58). Successful bone marrow therapy against lethal doses of busulphan in the rat has been described by Weston, Maxwell, Lee, Finzel and Fisken ('57) Dunn and Elson ('70a) conclude that the differences in action between busulphan and the aromatic nitrogen mustard derivative, amino-chlorambucil, [a-amino/p-( di-2-chloroethylamino)-phenyl/butyric acid], were due to their differing effects on bone marrow colony forming units (CFU's) as assayed by spleen colony formation in the rat. Busulphan was shown to produce a prolonged depression of CFU's, which precedes and, hence, is probably responsible for the fall in the Nucleated Cell Count (NCC) of the marrow; in contrast, aminochlorambucil, in a dose which produced a comparable fall in the NCC/femur to that following busulphan, had no discernible effect on CFU's.Since the conclusion reached by Till and McCulloch ('64) that the cell which gives rise to spleen colonies, i.e., the CFU, is the cell responsible for repopulation of mouse bone marrow after radiation-induced aplasia, this fact has been implied, or stated, in many reports. Rec...

Murine recovery from busulfan‐induced hematopoietic toxicity as assessed by three assays for colony‐forming cells

“…This survival effect might be a manifestation of a busulfan-induced stem cell defect. Dunn and Elson [24] found that rats salvaged from WBI by cells from BU-treated animals survived less well than those given normal cells, even though the two groups had comparable numbers of spleen colonies. However, death may not have been due to hematopoietic failure.…”

Capacity of Rat Haemopoietic Colony-Forming Units to Produce Differentiated Progeny

“…Haemopoietic colonies derived from bone marrow or spleen CFU were ob tained in both the bone marrow and spleen of groups of at least 5 rats treated with 30 mg/kg busulphan and 4 mg/kg aminochlorambucil according to the pre viously reported method [7], The mean number of endogenous colonies/spleen at 8.5 days after aminochlorambucil (corresponding to 8-day colonies) in all the ex periments now reported was less than 0.5. This number increased to 1.2±0.2 co lonies/spleen 12.5 days after aminochlorambucil (corresponding to 12-day colo nies).…”

“…The total num ber and histological type of colony in both the spleen and femoral bone marrow were obtained from microscopical analysis of 5-um-thick serial, longitudinal sec tions stained in haemotoxylin and eosin [5,7]. Except for megakaryocytic colonies (where 5 megakaryocytes or more were considered a colony) more than 100 cells were classified as a colony which was considered pure, i.e., consisting of one cell line only, unless it contained more than 10% of another cell type [5,7].…”