We previously demonstrated (Jiang et al., 2002) that rodent multipotent adult progenitor cells (MAPC) can self-renew long-term while maintaining multilineage differentiation capacity. Rodent MAPC express a number of pluripotency-related transcription factors (TF) including Oct4 and Rex1 but not Nanog and Sox2, two other TF known to play a significant role in the maintenance of the pluripotency of embryonic stem cells (ESC) (Ulloa-Montoya et al., 2007). However, rodent MAPC express several TF, including Gata4, Gata6, Sox7 and Sox17, typically expressed in the nascent hypoblast of the developing inner cell mass (ICM) (Nichols and Smith, 2011) and in the recently described rat extrambryonic endodermal precursor cells (rXEN-P), which are isolated from blastocyst (Debeb et al., 2009).
We derived in 4/12 independent isolations one or more rMAPC lines, by culturing rat BM cells in rMAPC medium (rMAPC isolation scheme, Supplementary Figure S1). After 4 weeks of culture, BM cells were depleted of CD45+ cells and 2–8 weeks later, clusters of refractile and small cells appeared, which became the preponderant cell type within 10 days (Figure 1A). Nearly all cells from the established lines expressed Oct4, Gata4, Gata6, Sox7 and Sox17 transcripts and proteins (Figure 1B and Supplementary Figure S2A and B), as well the surface markers SSEA1 and CD31 (Figure 1C and Supplementary Figure S2C), both markers of the early ICM.
