Deranged vessel formation of pure ECFCs in vivo and vascular lineage commitment in vitro. (A-C) Representative pure ECFCs (107) derived from large-scale single-step humanized expansion were resuspended in 0.2 mL phosphate-buffered saline and subcutaneously injected into nude mice. After one week, subcutaneous cell deposits (a macroscopic view is shown in Figure S6F) were processed for human CD31 histochemistry. (A) Overview appearance and (B,C) higher magnified regional view as indicated by schematic boxes with scale bars documenting magnification. ECFCs after large-scale expansion were also seeded into methylcellulose for hematopoietic colony-forming cell (CFC) assays. (D,G) Complete (10 cm2) assay plate overview, (E,H), 10× original magnification view, and (F,J) high magnification view that documents (D-F) complete lack of CFCs derived from ECFCs. In comparison, (G,H) regular red blood cell colony formation admixed with a hierarchy of differentially maturating white blood cell colonies and (J) less than 5% colony-forming units of granulocytes, erythrocytes, monocytes, and macrophages (CFU-GEMM) was derived from CD34+ hematopoietic progenitors.
