ABSTRACT
Differentiation of human embryonic stem cells (hESCs) into hematopoietic lineages using various methods has been reported. However, the phenotype that precisely defines the hematopoietic progenitor compartment with clonogenic activities has yet to be determined. Here, we measured and characterized progenitor function of subfractions of cells prospectively isolated from human embryoid bodies (hEBs) during hematopoietic differentiation basing on surface markers CD45, CD34, CD43, and CD38. We report that hematopoietic progenitors predominantly resided in the CD45(+) subset. CD43(+) cells lacking CD45 expression were largely devoid of progenitor activity. However, progenitor activity and multipotentiality was more enriched in CD45(+) cells co-expressing CD43. CD45(+) subset co-expressing CD34 but lacking CD38 expression (CD45(+)CD34(+)CD38(-)) were further enriched for CFU capacity compared to the CD45(+)CD34(+)CD38(+) subset. Our study demonstrates a role of CD43 in enriching hematopoietic progenitors derived from hEBs and reveals a hierarchical organization of hESC-derived hematopoietic progenitor compartments defined by phenotypic markers.
