Studies on the regulation of granulopoiesis. II. Relationship to other differentiation pathways

Can hypertransfusion attenuate myelosuppression associated with combination chemotherapy in patients with inoperable bronchogenic carcinoma? A report of a randomised, controlled study

Based on the concept of "stem-cell competition," hypertransfusion has been shown to attenuate the leucopenia associated with chemotherapy in children with leukemia. We conducted a randomized, controlled study of hypertransfusion in 25 patients with inoperable lung cancer who received combination chemotherapy consisting of methotrexate, adriamycin, cyclophosphamide, and CCNU (Lomustine) (MACC scheme). Twelve patients in the hypertransfusion group were given red cell transfusion to a hemoglobin value greater than or equal to 17 gm/dl prior to each chemotherapy cycle. The two groups of patients were comparable in age, cell type, extent of disease, performance status, and initial hemoglobin level and blood counts. The mean fall in granulocyte count was greater for control group (3.76 X 10(9)/liter) than for hypertransfusion group (3.27 X 10(9)/liter), and the mean fall in platelet count was greater for control group (53.84 X 10(9)/liter) than for hypertransfusion group (35.83 X 10(9)/liter), although the differences did not reach statistical significance (p greater than 0.05) partly because our MACC scheme was probably not sufficiently myelosuppressive to bring about a difference in the two groups. Granulocytopenia-associated infections were infrequent in both groups: two episodes in 37 cycles of chemotherapy in the hypertransfusion group and three episodes in 43 cycles in the control group. Hypertransfusion was simple and safe, and the encouraging trend towards less marked myelosuppression in our hypertransfused group would warrant further studies using more intensive and myelosuppressive combination chemotherapy regimens.

[Hematopoietic stimulation for enhanced bone marrow regeneration after chemotherapy (author's transl)]

The aggressivity of cancer chemotherapy is limited by hematologic side effects or makes expensive supportive therapy necessary. This article summarizes known and clinically usable methods of stimulating hematopoiesis to enhance bone marrow recovery after therapy. Longest known is the stimulatory effect of anabolic steroids, which may accelerate the regeneration of granulopoiesis and erythropoiesis. Lithium increases CSA-levels and enhances the regeneration of granulopoiesis and questionably thrombopoiesis according to several publications. The stem cell shift by hypertransfusion promotes granulopoiesis. As malnutrition limits hematopoietic recovery, optimal nutrition after chemotherapy should favor maximal hematopoiesis. Further studies are necessary before the application of the above mentioned methods to stimulate bone marrow - singly or in combination - can be recommended.

The importance of pluripotential stem cells in benzene toxicity

Several schedules of benzene exposure were evaluated for their effects on peripheral white blood cell counts, bone marrow cellularity and transplantable colony forming units (CFU-S) in male C57 Bl/6 mice. Intermittent exposure to 4000 ppm benzene in air produced leukopenia without altering the bone marrow cellularity. This same treatment, however, decreased the number of CFU-S to 30% of control values. Uninterrupted exposure to lower levels of benzene decreased peripheral cell counts within 24 h, and later decreased marrow cellularity. Exposure of a non-dividing population of stem cells (CFU-S) to benzene for up to 24 h produced no detectable effect on the subsequent development of spleen colonies, suggesting that the effect of benzene on CFU-S occurs only after peripheral cells are depleted. These findings indicate that benzene has affects on both differentiated cells and undifferentiated stem cells. An effect on the pluripotential stem cell is an important aspect of benzene toxicity, but not its exclusive or initial site of action.

The effects of erythropoietin in vitro on spleen colony-forming cells

Erythropoietin (epo) added to liquid cultures of mouse bone marrow cells effected both the numbers of spleen colony-forming cells (CFU) in the cultures and the types of spleen colonies formed from these cells in irradiated hosts. Epo caused an increase in the number of CFU detected in cultures on the second day; this effect persisted through day 10, with the maximal increase occurring on the seventh day. The magnitude of the rise on day 7 was proportional to the amount of epo added. The increase in spleen colonies found with cells cultured in the presence of epo was due solely to erythroid colonies. After seven days in culture without epo, there was a peak of cells that formed non-erythroid colonies. This peak did not appear when the cells were cultured in the presence of epo.

Effect of hypertransfusion on granulopoiesis in bone marrow depression: studies in the irradiated mouse

The response of granulopoietic activity in bone marrow depression to a reduction in the demand for erythropoiesis has been examined by means of hypertransfusing C-57B mice which had been exposed to sublethal whole body irradiation. Multiple intraperitoneal injections of 0.5 ml packed red cells from irradiated donors were employed to maintain the haematocrit sufficiently above the normal range to produce significant suppression of erythropoietic activity for the duration of the bone marrow depression. This was associated with elevation above control values of 32--102% in the blood granulocyte count, 22--78% in total cells of the granulocytic series per femur, and up to 44% in total agar colony forming units per femur. Restoration of essentially normal values occurred 13 d after irradiation in contrast to 17--18 d in controls. Single transfusions which produced less suppression of erythroblast numbers per femur resulted in an intermediate degree of improvement in these parameters. Such changes in the granulocyte compartment indicate improved granulopoietic capacity in the hypertransfused group. It is suggested that this effect reflects increased production of granulocyte progenitors due to the reduction in competing demands on the compromised multipotential stem cell compartment for progenitors of the erythroid series. The findings raise the possibility that hypertransfusion might be capable of producing a beneficial effect on granulopoiesis in human bone marrow depression.

Evidence of stem-cell competition in children with malignant disease. A controlled study of hypertransfusion

In a prospective, randomized controlled study, 30 children who were receiving chemotherapy for malignant disease and who were anaemic and neutropenic, were randomized: 18 to receive transfusion to a Hb of 10-12 g/dl (group A) and 12 to receive moderate hypertransfusion to a Hb of 14-16 g/dl (group B). Children in group B had a significantly more rapid rise in polymorph count, lower incidence of infection, and lower incidence of interruption to chemotherapy. The findings of this study provide evidence for the existence of a common stem cell in human marrow, at least for erythroid and myeloid cell lines, and demonstrate that the concept of "stem-cell competition" derived from animal experiments has a human counterpart which is clinically significant.