Two articles published in the journal Nature today continue to show that trying to turn the usual run of the mill cell into a stem cell (IPS Cells) is a really bad idea. One study by Gore showed that IPS cells picked up genetic mutations and changed the way their genetics interacted with the environment. In a second study by Hussein, IPS cells picked up SNP mutations (changes in specific parts of the genetic code), but these mutations tended to go away the longer you grew the cells. I have blogged in the past on problems with IPS cells, noting that messing with nature by trying to change normal cells into stem cells to satisfy a business need is not smart. The need for these cells when adult stem cells have already demonstrated that they can fix almost all human tissues is questionable. While in the long-run the basic science surrounding IPS is interesting and might one day yield some really interesting insights about how stem cells function, IPS cells are not ready for prime time.