On April 6, the journal Cell published work (subscription or online article purchase required) from the Salk Institute in San Diego, in which scientists have created a new “reprogrammed” stem cell.
These cells are called “extended pluripotent stem cells” or “EPS” cells. They are different from embryonic stem (ES) cells, which are removed from intact embryos that arise from fertilization—typically requiring specific creation and destruction of an embryo. Of course, ES cells can be human or non-human, depending on the source.
EPS cells are similar to “induced pluripotent stem cells,” or iPSCs, invented in 2006. The latter are generated from adult skin cells that have been reprogrammed, using genetic alterations.
EPS cells may be made by reprogramming ES cells or skin cells or, if I understand the work correctly, iPSCs. In this case, the reprogramming is done with a cocktail of chemicals in the lab.
But EPS cells are more capable than iPSCs. Unlike iPSCs, which can give rise to many different types of cells but not all—including not a placenta and not an entire intact new individual—EPS cells can do all of that. They are totipotent, meaning they can make all the cells of an individual from their species. Moreover, they are quite long-lived in the laboratory. EPS cells from one species—e.g., humans—can be placed into non-human (e.g., mouse) embryos to make hybrid animals that, it appears, survive quite well and can breed. And, remarkably, the authors of the Cell paper report (again, if I understand correctly, and I think I do) that they were able to use a mouse EPS cell to give rise to a whole new mouse, not “just” a laboratory tissue hybrid.
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