PHILADELPHIA – Fifty years ago, British researcher John Gurdon
demonstrated that genetic material from non-reproductive, or
somatic, cells could be reprogrammed into an embryonic state
when transferred into an egg. In 2006, Kyoto University
researcher Shinya Yamanaka expanded on those findings by
expressing four proteins in mouse somatic cells to rewind their
genetic clocks, converting them into embryonic-like stem cells
called induced pluripotent stem cells, or iPS cells. In early
October, Gurdon and Yamanaka were awarded the 2012 Nobel Prize
in Physiology or Medicine for their discoveries. Now, thanks to
some careful detective work by a team of scientists led by
Kenneth Zaret, PhD, at the Perelman School of Medicine,
University of Pennsylvania, researchers can better understand
just how iPS cells form – and why the Yamanaka process is so
inefficient, an important step to work out for regenerative
medicine. Zaret is associate director of the Penn Institute for
Regenerative Medicine and professor of Cell and