[Transfusional perspectives for ex vivo control of hematopoiesis].

Our increasing knowledge of the mechanisms of blood regulation allows us to envisage the production of cells in quantities sufficient enough to have transfusional interest. We present the state of the art on our capacity to amplify hematopoietic stem cells (HSC) and to force their differentiation into the erythroid lineage. We describe the difficulties met ex vivo for simultaneously reaching a very high level of expansion to have meaningful transfusional interests and obtaining a complete terminal maturation up to enucleation. We describe here a procedure for massively amplifying HSC from human cord blood to produce erythroblastic precursors able to differentiate in vivo into mature red cells after infusion. Although we do not suggest to replace classical blood transfusion, we consider that this approach may become complementary.