Cytosine arabinoside reduces the numbers of granulocyte macrophage colony forming cells (GM-CFC) and high proliferative potential colony forming cells (HPP-CFC) in vivo in mice.

Background: Cytosine arabinoside (Ara-C) is an S-phase specific cytotoxic drug used in the treatment of malignancies. It is converted to Cytosine Arabinoside triphosphate (Ara-CTP) in the cell. Cytosine Arabinoside triphosphate, reversibly displaces deoxy cytidine triphosphate from DNA polymerase for incorporation into DNA. This process leads to cell death.

Objective: To investigate the in vivo effects of Ara-C on the Granulocyte Macrophage Colony Forming Cells (GM-CFC) and High Proliferative Potential Colony Forming Cells (HPP-CFC) respectively in mice.

Methodology: Ara-C (150mg/kg) was administered intraperitoneally (i.p) once to mice and bone marrow cells sampled on days 1, 3 and 6.

Results: Ara-C reduced the numbers of both GM-CFC and HPP-CFC in the bone marrow. HPP-CFCs were initially more sensitive to Ara-C treatment than GM-CFCs. In the six days after treatment the effect on GM-CFC persisted, while there was a partial recovery in the number of HPP-CFCs.

Conclusion: It is possible that Ara-C disturbs the stem cells niche by damaging the stromal cells of the bone marrow microenvironment. This would result in derangement of HPP-CFC proliferation.