Reprogrammed stem cells ‘remember’ past life

Stem cells generated from adult cells still retain a memory of their past despite being reprogrammed, Australian scientists have found. Now scientists think they can teach the cells to forget their past.

Induced pluripotent stem (iPS) cells have huge potential in stem cell medicine. A skin cell, a heart cell, almost any cell can be persuaded to turn back into a stem cell and then turn into new tissues. But all’s not perfect.

Jose Polo with the late Don Metcalf. Credit: Mark Coulson/NSCFA
Jose Polo with the late Don Metcalf.
Credit: Mark Coulson/NSCFA

Jose Polo from the Australian Regenerative Medicine Institute in Melbourne and Ryan Lister from The University of Western Australia independently observed how, during cell development, changes are imprinted on the genes of the cell. Some of these epigenetic modifications remain when the cell is reprogrammed back into an iPS cell: it retains an epigenetic memory of what it was meant to be.

“This limits what the iPS cell can develop into and the uses to which it can be put,” Jose says. “But we might be able to take advantage of this bias to produce regenerative cells for a particular purpose.”

The two researchers made their discoveries overseas—Jose in Boston, and Ryan in San Jose. Then in Australia they started collaborating across the Nullarbor Plain on ways to reprogram the epigenetic memory, to persuade the cells to forget what they were destined to be.

Jose Polo was one of the two inaugural recipients of the National Stem Cell Foundation of Australia’s Metcalf Prizes for Stem Cell Research in 2014. Jose received $50,000 and mentoring from pioneering scientist Don Metcalf as part of his prize.

In 2014 Ryan Lister received the Prime Minister’s Prize for Life Scientist of the Year and in 2015 he won the Metcalf Prize. Both are recipients of Viertel Fellowships.

For more information: National Stem Cell Foundation of Australia, Julia Mason, CEO,,