Pluripotency of embryo-derived stem cells from rodents, lagomorphs, and primates: Slippery slope, terrace and cliff

The diverse cell states and in vitro conditions for the derivation and maintenance of the mammalian embryo-derived pluripotent stem cells raise the questions of whether there are multiple states of pluripotency of the stem cells of each species, and if there are innate species-specific variations in the pluripotency state. We will address these questions by taking a snapshot of our knowledge of the properties of the pluripotent stem cells, focusing on the maintenance of pluripotency and inter-conversion of the different types of pluripotent stem cells from rodents, lagomorphs and primates. We conceptualize pluripotent stem cells acquiring a series of cellular states represented as terraces on a slope of descending gradient of pluripotency. We propose that reprogramming pluripotent stem cells from a primed to a naive state is akin to moving upstream over a steep cliff to a higher terrace.