Studies of BFU-E in flask cultures of human peripheral and cord blood cells.

Early erythroid progenitors (the burst-forming units-erythroid or BFU-E) from human peripheral and cord blood mononuclear cells were maintained in flask culture for 2 weeks without added erythropoietin (Epo) or erythroid potentiating activity (EPA). These cultures did not develop adherent cell layers and did not support the more mature erythroid colony-forming unit (CFU-E). Samples removed at intervals from these flask cultures were assayed for BFU-E recovery in a plasma clot system in response to a range of Epo doses and to added EPA with time in flask culture. The BFU-E recovered showed increased proliferative capacity and decreased responsiveness to Epo and EPA. These results indicate selection of more primitive erythroid progenitor cells under the conditions described. Peripheral and cord blood mononuclear cell cultures provide a flexible and accessible approach to in vitro studies of human erythropoiesis. Comparative studies with long-term marrow cultures should help to elucidate the role of adherent cells and humoral factors in erythroid differentiation.