Low expression of stem cell antigen-1 on mouse haematopoietic precursors is associated with erythroid differentiation

Sca1 is a surface marker of haematopoietic stem cell but its role in erythropoiesis is still largely unknown. In this work we evaluated the ability of Sca1⁺ cells to differentiate into cells of the erythrocytic lineage. We performed FACS analysis of complete and purified Sca1⁺ bone marrow cells from C3H/HeNHsd mice and measured the expression of CD71 and Terr119 to evaluate the stages in erythroid development. Definitive erythropoiesis was evident within the complete bone marrow, while only proerythroblasts were found in Sca1⁺ cells, suggesting that Sca1 is a negative regulator of erythropoiesis. We also used FDCP-mix cells and their PU.1 and SCL transfectants. The PU.1 transfectant showed significantly increased expression of Sca1 and was not induced to differentiate into red blood cells, while the SCL transfectant showed significantly lower expression of Sca1 and produced red blood cells. The results of this study suggest that increased Sca1 expression on erythropoietic precursors inhibits erythroid differentiation.