Faculty Research 1980 - 1989

Hemoglobin switching in sheep: characteristics of BFU-E-derived colonies from fetal liver.


J E. Barker

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Cell-Differentiation, Colony-Forming-Units-Assay, Fetal-Hemoglobin: bi, Fetus: me, Hematopoietic-Stem-Cells: cy, me, Hemoglobin-C: bi, Liver: em, cy, me, Sheep: me, Time-Factors

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Blood. 1980 Sep; 56(3):495-500.


Two types of erythroid colonies were generated in vitro from sheep fetal liver cells. The first type consisted of single colonies of 8-256 cells that were well hemoglobinized by 4 days; these are thought to originate from CFU-E. The second type consisted of macroscopic colonies composed of several subcolonies that matured between days 3 and 8 in vitro. At maturity, each contained 256 to > 1000 cells that formed a discrete macroscopic cluster. The macroscopic colonies, not previously described in sheep, are thought to be derived from BFU-E. The characteristics of sheep BFU-E were defined and the production of fetal hemoglobin (HbF, alpha 1, gamma 2) and HbC (alpha 2 beta 2) was compared in colonies derived from CFU-E or BFU-E. Bursts developed at erythropoietin (epo) concentrations as low as 0.1 U/ml, although the number observed increased with epo concentration up to 10 U/ml. The number of bursts observed was approximately proportional to the number of cells plated. As shown by thymidine suicide, approximately 50% of both the BFU e and CFU-E were in S-phase when obtained from the fetus. BFU-E were smaller and partially separable from CFU-E after sedimentation at unit gravity. The beta c/gamma synthetic ratio in colonies derived from BFU-E was greater than in CFU-E-derived colonies. These data suggest that the capacity for generation of erythroblasts making HbC is greater in the earlier or more primitive erythroid stem cells in fetal liver.