An Important Proof for iPS Cells
Researchers have demonstrated an important proof of the capabilities of induced pluripotent stem (iPS) cells: "Since Shinya Yamanaka of Kyoto University in Japan created the first iPS cells in 2006, researchers have wondered whether they could generate an entire mammalian body from iPS cells, as they have from true embryonic stem cells. ... the team reports 27 live births. With their best cell line and optimal recipe, they were able to get 22 live births from 624 injected embryos, a success rate of 3.5%. ... the mice seem to have a high death rate, with some dying after just two days, and others displaying physical abnormalities, details of which the team would not reveal. But some of their mice passed one of the most fundamental tests of health: all 12 mice that were mated produced offspring, and the offspring showed no abnormalities. The team says it now has hundreds of second-generation, and more than 100 third-generation, mice. The team found no tumours in the mice, although they have not systematically looked for them." You might look at this as analogous to early cloning attempts - high failure rates and abnormalities in early efforts are beside the point. The point is that the process works, will be rapidly improved, and some form of induced pluripotent stem cells can eventually be substituted for embryonic stem cells for every application.
Link: http://www.nature.com/news/2009/090723/full/460560a.html