HUMAN MARROW CELLS CAPABLE OF ERYTHROPOIETIC DIFFERENTIATION INVITRO - DEFINITION OF 3 ERYTHROID COLONY RESPONSES

  • 1 January 1977
    • journal article
    • research article
    • Vol. 49  (6) , 855-864
Abstract
A systematic study was undertaken to analyze the spectrum of erythropoietic colonies obtained in cultures of human marrow cells plated in methyl cellulose. Colonies were identified as erythropoietic on the basis of the appearance in them of Hb-containing erythroblasts. As found previously in mouse marrow cultures, 3 sequentially appearing types of colonies which differed in their ultimate cluster content were readily distinguished. Small erythroid colonies containing 1-2 clusters reached a peak after 7-8 days; small bursts containing 3-8 clusters reached a peak after 10-12 days; and large bursts containing >16 clusters reached a peak after 17-20 days. The previously reported enhancing effect of human leukocyte conditioned medium on burst formation seen in cultures of human nonadherent cells was due largely to an effect on the formation of the largest, late appearing type of burst. By analogy with the mouse, the progenitors of such bursts would represent a primitive cell type which has a close relationship with pluripotent stem cells, as well as a 2nd and independent close relationship to the progenitors of granulopoietic colonies.