Culture studies of human pluripotent hemopoietic progenitors.

Abstract

Culture conditions are described that promote the growth of human pluripotent hemopoietic progenitors and facilitate their quantitation. These primitive cells form mixed colonies that may contain all elements of myeloid differentiation, including granulocytes, erythroblasts, megakaryocytes, and macrophages. Some mixed colonies contain, in addition to mature progeny, early progenitors that can be identified by their ability to form secondary hemopoietic colonies. The production of secondary mixed hemopoietic colonies by cells present in redispersed primary mixed hemopoietic colonies supports the view that some CFU-GEMM may self-replicate in culture, thus fulfilling one of the major operational requirements for pluripotent hemopoietic stem cells. Assessment of the proliferative state of CFU-GEMM under steady state conditions and in various clinical disorders suggests that the proliferative activity may reflect conditions that are associated with perturbations at the level of pluripotent progenitors. The recently observed increased plating efficiency of approximately 10 mixed colonies per 105 plated mononuclear cells will facilitate investigation of regulatory events at the level of pluripotent progenitors. With the use of putative stimulators, it might be feasible to modulate the cellular composition of mixed colonies and thus, identify mechanisms that determine the choice of pluripotent cells to self-replicate or to differentiate and mature into cells of specific phenotype.