This invention provides a system for producing cells of the hematopoietic lineage from embryonic stem cells. Differentiation is conducted in the presence of hematogenic cytokines and other factors listed in the disclosure. The cell population that is obtained is remarkably enriched in CD45 +ve cells, a marker of early hematopoietic precursor with self-renewing capacity. Including a bone morphogenic protein during the differentiation process enhances the ability of the cell population to form secondary colonies. Because of the enormous replicative capacity of embryonic stem cells, this provides an important new commercial source of hematopoietic cells.
