Microarray analysis of IdHP cells compared to LKS, Control ProB and E2A-/- progenitors

Self-renewal potential and multipotency are hallmarks of the stem cell1-3. It is generally conceived that acquisition of such a stemness requires rejuvenation of somatic cells through reprogramming of genetic and epigenetic status. We show here that a simple blockage of cell differentiation is sufficient to make stem cells. By over-expression of transcriptional repressor Id3 in murine hematopoitic progenitor cells and cultivation of these cells in B cell induction conditions, cells exhibit developmental arrest and enter a self-renewal cycle. These cells can be maintained in vitro almost limitlessly, and the long-term cultured cells exhibited robust multi-lineage reconstitution when transferred into irradiated mice. These cells can be cloned and re-expanded with 50% of plating efficiency, indicating that virtually all cells are self-renewing. Equivalent progenitors were produced from progenitors in human cord blood. Thus produced stem cells will be useful as the source of cells for immune cell therapy. Four samples