Expression of PRL-R chimeric receptors and hematopoietic progenitor levels after in vitro hematopoietic differentiation of ES cells.

(A) Chimeric receptor expression was determined in undifferentiated ES cells (D0) and in embryoid bodies (EBs) 12 days after induction of differentiation (D12) by RT-PCR. Thirty-five cycles of PCR were performed, and the specificity of the PCR products was confirmed by Southern blot analysis with a specific internal oligonucleotide. (B) Hematopoietic progenitor content analysis of D12 EBs. EBs were collected, dissociated in collagenase solution and their hematopoietic progenitor content established by clonogenic assays in the presence of 7GF cocktail 12 days after induction of hematopoiesis. Colonies were scored 7 days later (D12 + 7). Types of colonies (CFU): ■, granulocyte-macrophage (-GM); ▤, burst-forming unit-erythroid (BFU-E); ▪, mixed (-Mixt).