Developmental potential of human blast colonies. (A) Photograph showing the adherent and nonadherent population generated from an individual 6-day-old blast colony plated on a thin layer of matrigel in media containing both hematopoietic and endothelial cytokines. (B) Expression analyses of the nonadherent and adherent populations generated from 6 individual blast colonies. The colonies were grown from day-4 EB-derived KDR-positive cells. (C) Immunostaining and DiI-Ac-LDL uptake of adhesive cells generated from a single blast colony. CD31 expression is indicated by green fluorescence and LDL uptake by red fluorescence. Original magnification: × 400. (D) Cell dose-response showing the relationship between the number of day-4 EB cells plated and the number of blast colonies that develop. (E) Photograph of a blast colony generated from a single KDR⁺ cell and of the adherent and nonadherent populations generated from it. Single KDR⁺ cells from day-3 EBs were deposited into microtiter wells containing methylcellulose. After 6 days of culture, the colony was picked from the microtiter well and cultured on a thin layer of matrigel for an additional 6 days. Original magnification for the colony and expanded populations: × 400.