ABSTRACT
The ability to derive hematopoietic cells from human embryonic stem (ES) cells lead to an innovative means to prevent immunologic rejection of other human ES cell-derived cells. Speculation regarding the ability to co-transplant human ES cell-derived HSCs along with a second human ES cell-derived cell type of interest in order to induce tolerance has been described elsewhere. Hematopoietic colony-forming assays involve placing a single cell suspension in semi-solid methylcellulose-based media containing hematopoietic cytokines or growth factors. Typically blood or bone marrow cells are used, but in this case, differentiated human ES cell-derived cells can be analyzed. Under these conditions, a single hematopoietic colony-forming cell (CFC) will repeatedly divide to form a large cluster of cells that can be characterized based on the stereotypic appearance of the colony. The CFC assay has probably been the most important means to characterize hematopoietic precursor cells derived from human ES cells.
