Single‐cell RNA sequencing reveals the landscapes of human cord blood hematopoietic stem cell differentiation during ex vivo culture

Here, we established an expansion strategy using a combination of cytokines (SCF, TPO, FLT3-L and IL-6) and USK (UM171, SR1 and K1) that contributed to a 543-fold increase relative to the initial cell population in CD34+CD38–CD45RA–CD90+ cells (Figure 1A–C, Tables S1 and S2). [...]colony-forming units assay confirmed that the cells cultured with USK, UM171 or K1 retain the ability to differentiate into multilineage progenitors (Figure 1D, Table S3). SEE PDF] Recent studies hold that the cell-surface markers used for isolation of HSCs are inaccurate for ex vivo culture of HSCs.8 Similar to our study, Chen et al.9 found that ex vivo expanded cells with a phenotype of CD34+CD38–CD45RA–CD90+CD49f+ were not functional HSCs. [...]it may be inappropriate to previously define CD34+CD38–CD45RA–CD90+ as a marker for long-term hematopoietic stem cells (LT-HSCs) during ex vivo culture. [...]we analyzed HSC-related transcription factors and their target genes.