Long-term culture of chronic myeloid leukemia (CML) bone marrow cells

Clonal Ph1+ hematopoiesis is not allowed to proliferate under a long-term culture system: in 3,4 weeks residual normal (Phl-) hematopoiesis emerges. This culture system has recently been proposed as a method for purging autografts.

In our study we evaluated for cytogenetic conversion cells harvested from the non-adherent (NA) fraction of LTBMCs from CML patients. Moreover we investigated the effects of prior therapy (busulfan or hydroxyurea) on CML hematopoiesis maintained under long-term culture.

Time-course analysis of a large number of metaphases of NA cells from LTBMCs showed that the disappearance of Ph1+ cells is fortuitous. Although most of the analyzed cells were more mature cells, a complete cytogenetic conversion at the level of the early hematopoietic compartment, located within the adherent stromal layers, seems unlikely, at least for the first 3,4 weeks of culture. Thus the possibility exists of reinfusing an indefinite number of Ph1+ progenitor or stem cells, which renders proper evaluation of the clinical benefits of this purging method difficult. Moreover we found that prior chemotherapy (busulfan or hydroxyurea) significantly affected CML hematopoiesis, reducing time-course recovery of clonogenic cells from LTBMCs.

Overall data suggest caution in the reinfusion of bone marrow cells maintained under long-term culture for previously treated CML patients.