Enhanced megakaryocyte repopulating ability of stem cells surviving 5-fluorouracil treatment.

The effect of 5-fluorouracil treatment of donor mice on the capacity of transplanted bone marrow to produce megakaryocytes in the spleens of lethally irradiated recipients has been examined. At both 10 and 13 days after transplantation, the spleens of recipients of 5-fluorouracil treated bone marrow had significantly more megakarocytes per unit area of spleen section than recipients injected with an equivalent number of spleen colony forming units from normal bone marrow. It is suggested that such treatment may provide a sensitive in vivo system for the investigation of endogenous factors influencing megakaryocyte progenitor proliferation. The results are consistent with the concept of stem cells being heterogeneous with respect to self-renewal capacity.