Isolation of and quantification of BFU-E and CFU-E cells from primary samples. (A) Representative plot of a combination of surface markers that isolates BFU-E and CFU-E populations from primary human BM samples. (i) Plot of SSC vs CD45 expression of all cells being analyzed; (ii) SSC vs CD3, CD4, CD14, CD19, and 7AAD of CD45+ population (P1), the resulting negative population designated as P2; (iii) SSC vs CD41 and GPA of the P2 population, namely P3; (iv) SSC vs IL3R expression of the P3 population; (v) SSC vs CD36 expression of IL3R⁻ population, resulting in CD36⁻ and CD36⁺ populations; (vi, top) CD34 vs SSC of the CD36⁻ population revealed CD34⁺, which gave rise to BFU-E colonies; (vi, bottom) CD34 vs CD71 of BFU-E population revealed that BFU-E cells were CD34+CD71low; (vii, top) CD71 vs SSC of the CD36⁺ cells revealed CD71⁺ population, which gave rise to CFU-E colonies; and (vii, bottom) CD34 vs CD71 of CFU-E population revealed that CFU-E cells are CD34⁻CD71^hi. (B) Colony forming ability of the sorted BFU-E and CFU-E cells from BM (i), cord blood (ii), and peripheral blood (iii). (C) Quantitative analysis of BFU-E and CFU-E populations in cord blood and peripheral blood.