Growth kinetics of CFU-GEMM, BFU-E, and CFU-C in diffusion-chamber cultures of normal human bone marrow cells.

The proliferation and differentiation of human pluripotent hemopoietic precursor cells CFU-GEMM as well as of the committed precursors BFU-E and CFU-C within conventional diffusion chambers (DC) was studied. Low-density human bone marrow cells from eight normal donors were cultured in DC implanted into 750-rad-preirradiated mice. Cells harvested from DC after 1-14 days were assayed for the content of CFU-GEMM, BFU-E, and CFU-C. The mean number of progenitor cells inoculated per DC on day 0 was 59 (range 12-144) for CFU-GEMM, 367 (range 165-878) for BFU-E, and 632 (range 122-1168) for CFU-C. After an initial decrease in the number of all progenitors, an increase of CFU-GEMM was observed in five out of eight experiments and in the number of BFU-E and CFU-C in seven and five experiments, respectively. The assessment of the percentage of precursor cells sensitive to ara-C demonstrated a rise in the proportion of cells in S phase after implantation into DC consistent with reentry into active proliferation. From the observed behavior of the CFU-GEMM it is concluded that the earliest detectable human precursor cells do proliferate within DC.