Figure 4.

In vitro expansion system for analyses of primary adult bone marrow–derived erythroblast development. (A) In the system outlined, hematopoietic progenitor cells (HPCs) were isolated (here, from WT control bone marrow preparations) as Kit⁺ cells, and expanded in cytokine- and dexamethasone-supplemented SP34-EX. During expansions, CD117 (Kit) and CD71 (transferrin receptor) expression was monitored (lower panels). Morphologies of expanded and FACS-isolated Kit⁺CD71^high and Kit^–CD71^high erythroblasts also were analyzed and are presented at ×400 magnification. MACS, magnetic-activated cell sorting; APC, allophycocyanin. (B) Differentiation capacities of expanded erythroblasts were assessed based on forward-angle light scatter (FALS), Ter119 and CD71 marker expression, and morphologies after transfer to a medium containing insulin, Epo, and transferrin. Magnification, ×1000.