Reprogramming of committed cells from one lineage to another is possible in the hematopoietic system using enforced expression of transcription factors. Here we describe methods to convert committed B and T progenitors into macrophages. In order to obtain a labeled population of starting cells, we employ a lineage ancestry system using a cross between lineage-specific Cre recombinase mice and Rosa26 reporter mice. After infection of these well-defined cell populations with a transcription factor containing retroviral vector that also harbors an infection marker, cells are cultured under conditions permissive for both lymphoid and myeloid development. Multicolor flow cytometry is then used to monitor changes in marker expression on the cell surface reflecting changes in cellular identity. These protocols may be modified to trace cellular reprogramming induced by other transcription factors and in other cellular contexts.
