Pre-progenitor cells: a proposed new category of hematopoietic precursor cells

Hematopoietic precursor cells capable of forming blast colonies in vitro appear to be a distinct transit population between stem cells and lineage-committed progenitor cells because the cells in such blast colonies are mainly lineage-committed progenitor cells. It is proposed that blast colony-forming cells be termed pre-progenitor cells (PPC) to encourage efforts to establish their biology and potential for initiating some types of leukemic populations more clearly.