Abstract: In vitro production of clinically useful quantities of mature, differentiated human blood cells by a method in which human pluripotent hematopoietic stem cells, preferably from a universal donor, are incubated in a bioreactor in a growth medium also containing specific recombinant human growth and maturation promoting polypeptide factors in combinations that expand stem cell cultures and promote the maturation and differention of stem cells into erythroid, thrombocytic or granulocytic human blood cells, and harvesting the mature cells. The growth and maturation promoting polypeptides employed include SCGF, Interleukins 1,3,4,5,6, and 11, GM-CSF, M-CSF, G-CSF and EPO. Stem cells may be modified so as to remove histocompatibility and/or blood group antigens, or may be genetically altered by transfection with appropriate DNA-containing vectors, prior to addition to the bioreactor.

Abstract: The present invention relates to a method of amplifying in vitro stemcells. In this method hematopoietic CD34.sup.+ stem and progenitor cells are isolated from human bone marrow and contacted with endothelial cells. The contacted stem cells and endothelial cells are cultured in the presence of at least one cytokine in an amount sufficient to support amplification/expansion of the hematopoietic CD34.sup.+ stem and progenitor cells. This method produces increased yields of hematopoietic CD34.sup.+ stem and progenitor cells which can be used in human therapeutics.