Toronto discovery stuns stem cell world

Neural-like cells derived from stem cells could save a brain. Photo: Stephen Elliman, Wellcome Images

We’ve often blogged here about our local strengths in stem cell science. Ontario has an illustrious track record in this field – we were first to prove the existence of stem cells (1), we discovered cancer stem cells (2) and have recently shown ways to predict whether a stem cell will become cancerous or not (3).

We have developed into a leading world centre and have struck partnerships with illustrious international groups including Shinya Yamanaka’s team in Japan and researchers throughout California.

And now Dr. Andras Nagy’s team at the Mount Sinai Hospital in Toronto has achieved the seemingly impossible – they have found a way to make induced pluripotent stem cells (iPS cells) without viruses and (wait for it) the reprogramming genes can be removed once they’ve done their job!

The discovery is described in a paper entitled “piggyBac transposition reprograms fibroblasts to induced pluripotent stem cells” in the March 1 edition of Nature – the world’s leading scientific journal.

What does this all mean? Well, it means it is now much easier and safer to generate stem cells from adults. It means that there is far less concern about the cells causing cancer. It means that iPS cells have now moved much closer to clinic.

Unlike embryonic stem cells, iPS cells are usually generated from adult tissues such as a skin biopsy. The iPS cells have the ability to develop into any human tissue but there are no ethical concerns surrounding their production. Not only that, the fact that cells are patient-derived means that there is no concern about immune rejection.

In essence, an iPS cell is the starting point for producing patient-specific therapeutic cells to treat diseases of the heart, liver, CNS, skin, blood, joints, and so on. As if that were not enough, iPS cells provide an effective and accessible tool for modeling human diseases in the test tube.

We salute Dr. Nagy and his team. Outstanding job!


1. Becker AJ, McCulloch EA, Till JE (1963) Nature 197:452-4
2. Bonnet D, Dick JE (1997) Nature Medicine 3:730–7
3. Werbowetski-Ogilvie TE et al (2009) Nature Biotechnology 27:91-97