Dose intensity for breast cancer: where do we go from here?

Enhanced proliferation of functionally competent bone marrow cells in different strains of mice treated with swainsonine

The immunomodulatory alkaloid swainsonine (8alphabeta-indolizidine-1alpha,2alpha,8beta-triol) has potential for overcoming the bone marrow suppressive effects of cancer chemotherapy and radiotherapy. An earlier study showed that multiple doses of swainsonine enhanced bone marrow cellularity in four different strains (C57BL/6; C3H-HEN; Balb/C and DBA-2 mice) of inbred mice which were not exposed to any chemotherapeutic agents or radiation. In vitro assessment of total colony formation capacity of bone marrow cells (BM CFUs) showed a 2- to 8-fold increase in swainsonine-treated mice compared to control mice that were given sham injections of physiological saline. In the current study, we have evaluated the functional competence of the bone marrow cells produced in response to swainsonine treatment of normal healthy mice. In particular, colony forming units-granulocyte-macrophage (CFU-GM), erythroid-burst forming units (BFUe) and CFU-Mix (or CFU-granulocyte-erythrocyte-monocyte-megakaryocyte (CFU-GEMM)) levels, were determined using in vitro assays. The time course of the changes in CFU-GM, BFUe and CFU-Mix (CFU-GEMM) were also followed. Our results demonstrate that swainsonine bolsters the CFU capacity of BM cells without loss of function to levels which are several folds higher than in sham-treated control mice. Swainsonine treatment caused an increase in all lineages of marrow cells without loss of function. This effect was reproduced in all four strains of inbred mice in this investigation. Examination of the peripheral blood did not reveal increase in white blood cells or changes in the hematocrit levels. The long-term effects of swainsonine treatment are not known at present. Nonetheless, swainsonine-induced increase in CFU capacity of bone marrow cells and related cells along the different differentiation paths should find clinical application in cancer treatment with chemotherapeutic agents and/or radiation.

Swainsonine stimulates bone marrow cell proliferation and differentiation in different strains of inbred mice

The immunomodulatory alkaloid swainsonine (8alphabeta-indolizidine-1alpha,2alpha,8beta-triol) has potential for overcoming the bone marrow suppressive effects of cancer chemotherapeutic drugs and radiation. The effect of swainsonine on bone marrow cellularity was evaluated in four different strains (C57BL/6; C3H-HEN; Balb/C and DBA-2 mice) of inbred mice subjected to multiple doses of the alkaloid. Swainsonine treatment stimulated bone marrow cell proliferation in all strains of mice. Examination of the peripheral blood did not reveal any increase in total leukocyte count. In vitro assessment of total colony-forming unit (CFU) capacity of bone marrow cells showed a two- to eight-fold increase in swainsonine treated mice of different strains compared to their corresponding controls given sham injections of physiological saline. Swainsonine induced increase in CFU capacity of bone marrow cells should find clinical application in cancer treatment with chemotherapeutic agents and radiation.