Development of hematopoietic stem and progenitor cells from mouse embryonic stem cells, in vitro, supported by ectopic human HOXB4 expression.

Differentiation of pluripotent embryonic stem (ES) cells can recapitulate many aspects of hematopoiesis, in vitro, and can even generate cells capable of long-term multilineage repopulation after transplantation into recipient mice, when the homeodomain transcription factor HOXB4 is ectopically expressed. Thus, the ES-cell differentiation system is of great value for a detailed understanding of the process of blood formation. Furthermore, it is also promising for future application in hematopoietic cell and gene therapy. Since the arrival of techniques which allow the reprogramming of somatic cells back to an ES cell-like state, the generation of hematopoietic stem cells from patient-specific so-called induced pluripotent stem cells shows great promise for future therapeutic applications. In this chapter, we describe how to cultivate a certain feeder cell-independent mouse embryonic stem cell line, to manipulate these cells by retroviral gene transfer to ectopically express HOXB4, to differentiate these ES cells via embryoid body formation, and to selectively expand the arising, HOXB4-expressing hematopoietic stem and progenitor cells.