Scientists in Japan have developed a way to cheaply and easily take adult cells from mice and reprogram them back to a pluripotent or embryonic-like state. They demonstrated that these STAP cells were capable of becoming all the cells in a full grown mouse.
They call the technique “stimulus-triggered acquisition of pluripotency” or STAP. Unlike, induced pluripotent stem cells (iPSCs) that use viruses to reprogram a very small percentage of adult cells back to pluripotency, STAP uses stressors like acid baths or physical pressure to quickly reprogram a much larger portion of cells. Nature News has the story:
In 2006, Japanese researchers reported a technique for creating cells that have the embryonic ability to turn into almost any cell type in the mammalian body — the now-famous induced pluripotent stem (iPS) cells. In papers published this week in Nature, another Japanese team says that it has come up with a surprisingly simple method — exposure to stress, including a low pH — that can make cells that are even more malleable than iPS cells, and do it faster and more efficiently….
Obokata says that the idea that stressing cells might make them pluripotent came to her when she was culturing cells and noticed that some, after being squeezed through a capillary tube, would shrink to a size similar to that of stem cells. She decided to try applying different kinds of stress, including heat, starvation and a high-calcium environment. Three stressors — a bacterial toxin that perforates the cell membrane, exposure to low pH and physical squeezing — were each able to coax the cells to show markers of pluripotency….
But her results suggested a different explanation: that pluripotent cells are created when the body’s cells endure physical stress. “The generation of these cells is essentially Mother Nature’s way of responding to injury,” says Vacanti, a co-author of the latest papers.
The next step is to see if STAP works in human cells as well.
STAP would eliminate the dangers of using viruses to reprogram cells and the ethical issues with the growth of those viruses in cell lines that came from aborted fetuses.
But STAP may have more serious ethical issues. Pluripotent stem cells from either an embryo or from reprogramming adult cells cannot become placenta. This means that these cells are not complete organisms that could implant and grow into a fetus if placed in a surrogate mother. In contrast, STAP cells can make placenta in mice. This begs the question: Could STAP be used for reproductive cloning?
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This scenario is already in the minds of scientists:
One of the most surprising findings is that the STAP cells can also form placental tissue, something that neither iPS cells nor embryonic stem cells can do. That could make cloning dramatically easier, says Wakayama. Currently, cloning requires extraction of unfertilized eggs, transfer of a donor nucleus into the egg, in vitro cultivation of an embryo and then transfer of the embryo to a surrogate. If STAP cells can create their own placenta, they could be transferred directly to the surrogate. Wakayama is cautious, however, saying that the idea is currently at “dream stage”.
If STAP is successful with human cells, will STAP cells be capable of creating human placental cells as well? The answer very well may be, No.
I wonder if STAP will be another tool in the arsenal of stem cell science or if it may open the door to human cloning. I suppose time will tell.
Either way STAP is something we should definitely keep on eye on.