Fig. 4
Cell surface antigen expression discriminates the three MEP subpopulations identified by single-cell gene expression analysis. a Mean fluorescence intensity (MFI) of eight surface antigens included in the FACS panel for the three populations assigned by PCA. Population 1 (green) contained cells with significantly higher CD34, CD123, and CD45RA and lowest CD38, CD71, CD41, and CD42 expression. Population 2 (purple) identified as CD71 + 41- and Population 3 (orange) as CD71 + 41+. b Cell surface antigens included in the qPCR profile panel but not the FACS panel were considered to further refine the immunophenotyping strategy. CD44 expression emerged from the qPCR data as the most differentially expressed surface antigen associated with Population 1 (P <0.0001). Star indicators represent significance values (KS test with FDR correction) between populations: *-q <0.05; **-q <0.01; ***-q <0.001; NS-q >0.05. Data are shown as bee-swarm plots in which the log2 MFI values (a) or relative mRNA expression level (b) of individual cells are represented as dots with a box plot overlaid. c The utility of CD44 immunophenotyping was validated by flow cytometry, confirming that high surface expression of CD44 correlates with the CD71- CD41- MEP subfraction. Numbers shown correspond to the three MEP subsets: Population 1, CD44hi 71- 41- ; population 2, CD71 + 41-; population 3, CD71 + 41+