Embryonic lineages may emerge from embryonic stem cells and induced pluripotent stem cells, which are generally considered pluripotent, not totipotent, because they have not been thought capable of giving rise to extraembryonic cell types, specifically, placental trophoblasts.
The University of Missouri researchers were attempting to isolate trophoblast stem cells from human embryonic stem cells that had been exposed, briefly, to a factor called bone morphogenetic protein.
“These new cells, which we are BMP-primed stem cells, are much more robust and easily manipulated than standard embryonic stem cells,” said Dr. Roberts.
“BMP-primed cells represent a transitional stage of development between embryonic stem cells and their ultimate developmental fate, whether that is placenta cells, or skin cells or brain cells. We can use these new stem cells for future research to better understand how embryos are organized.”
“Here, we report the acquisition of a unique stem cell phenotype by both human ES cells and induced pluripotent stem cells in response to transient exposure to bone morphogenetic protein 4 plus inhibitors of ACTIVIN signaling and FGF2,” wrote the authors, “Followed by trypsin dissociation and recovery of colonies capable of growing on a gelatin substratum in standard medium for human PSCs at low but not high FGF2 concentrations.”
“Previously, the common thought was that embryonic stem cells transitioned straight from stem cells to their end products,” explained Dr. Roberts.
“These new stem cells made us realize that embryonic stem cells exist in a number of different transitional states, which likely resemble those encountered in the early stages of embryos. This should open the door for future stem cell research that is much more efficient. We now have new stem cells that are easier to manipulate since they are already at the key transitional precipice before changing into placenta cells, skin cells, or any other kind of cell that makes up the human body.”