Aug. 6, 2008
Dr. Rudolf Jaenisch and his team at MIT have upped the stakes in the race to perfect the iPS (induced pluripotent stem) cell technique first developed by Dr. Shinya Yamanaka of Japan in 2006. The technique directly reprograms a normal cell, such as a skin cell, using 3-4 genes added to the cell via viruses. The iPS cells behave like embryonic stem cells but do not use embryos, eggs, or cloning, thus bypassing the ethical problems inherent in deriving embryonic stem cells from embryos or clones. Yamanaka first developed the method in mice, then transferred the same process to use with human cells, without ever using human embryos or human embryonic stem cells in his research. One of the concerns with the iPS cell technique has been the use of viruses to reprogram the cells. While the added viral genes seem to be turned off once they have accomplished their job, use of viruses leaves a lingering doubt about normalcy or the safety of such cells (in addition to the safety problems of every embryonic stem cell.)
Now Jaenisch's team has shown that they can use a soluble protein, Wnt, to stimulate part of the reprogramming. Using a Wnt solution and only 3 added genes, they were able to get enhanced efficiency at reprogramming mouse cells into iPS cells. They note that the mouse iPS cells they produced "are morphologically and functionally indistinguishable from ESCs." There are still other factors to work out to eliminate viruses completely from the mix, but iPS cells continue to advance rapidly, while the dodgy cloning technology continues to fail and fall behind.
The results are published (subscription required) in the August 7 issue of Cell Stem Cell.