Cells, it turns out, remember where they came from. Four years
ago, scientists made a breakthrough in stem cell research, when
they discovered how to turn back the developmental clock on skin
cells, muscle cells, and other “adult” cells so the cells would
behave like embryonic stem cells. These induced pluripotent stem
cells (iPS cells) were touted as an alternative to the ethically
contentious embryonic stem cells. Now, though, two groups of
Howard Hughes Medical Institute researchers report that iPS
cells retain a genetic memory of their tissue of origin. In a
sense, the iPS cells “remember” that they came from skin,
muscle, blood, and so on. This memory impedes the transformation
of iPS cells into other types of cells, a prospect that has deep
implications for researchers working with these kinds of cells,
say HHMI investigator George Q. Daley and HHMI early career
scientist Konrad Hochedlinger, who led the two research groups.
The scientists worked independently but shared manuscripts and
coordinated join