Fetal blood-borne myelo- and thrombopoietic stem cells in diffusion chambers.

The potential of hematopoietic stem cells from cord blood for proliferation and differentiation have been studied by the diffusion chamber technique. In a pilot study, it was shown that blast cell production and myelopoiesis from the original lymphoid cell suspension starts 6 days after implantation. Mature granulocytes and megakaryocytes respectively appear in the chambers from the 16th and 10th days onwards. Myelopoiesis is ten times more active in fetal than in adult blood. There were thrombopoietic stem cells in 7 of 10 cord blood samples but in only one of 10 adult blood specimens. It is concluded that the high hematopoietic activity of the bone marrow at term is reflected by an increase in the number of stem cells circulating in the blood. Myelo- and thrombopoietic stem cells must be sought among the lymphoid cells of the original cord blood cell suspension.