12/04/2007, 00.00
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Kyoto University scientists break stem cell safety barriers

by Pino Cazzaniga
Dr Shinya Yamanaka’s research team eliminates the risks of cell mutation and the danger of tumors. Now it is working on finding a safe artificial genetic factor.

Tokyo (AsiaNews) – At Kyoto University the Institute for Frontier Medical Science team under Shinya Yamanaka, which found a way to convert human cells to embryo-like stem cells, is now working on eliminating the risk of tumors.

Dr Yamanaka’s first breakthrough, which AsiaNews  announced on November 23, showed how stem cells could be produced without using embryos, thus eliminating any ethical problems. The technique consists in re-programming human adult cells by inserting four genetic factors which a play a role in embryo development.

Many scientists have welcomed the discovery as a great breakthrough because it opens the way to the development of therapies based on replacing worn-out tissues with new ones.

However, we are still a long way from any therapeutic application of this discovery. Dr Yamanaka himself urges prudence.

“From about 50,000 transfected human cells, we obtained approximately 10 iPS cell clones,” he said. Indeed, he is conscious that it will take time before therapies can be developed based on the use of stem calls. And stem cell safety issues will have to be addressed since undesirable mutations like tumors can be caused.

Yamanaka and his team have moved however on a fast track. Last Friday US medical journal Nature Biotechnology reported that the Kyoto University group was able to re-program human skin cells and create induced Pluripotent Stem cells (iPS cells) without using c-Myc, the oncogene that can cause cancer.

This was not achieved in the ten days, that is between announcement of the team’s first and second breakthrough. Over a period of a hundred days (crucial in tumor development) they developed iPS cells with only three genetic factors, without inserting the c-Myc. Unlike mice that received the four genetic factors, none of those tested without c-Myc died from cancer. However, the iPS cells generated this way were less powerful that those created with the c-Myc. The next step for the research team is to find an artificial genetic factor that can take the place of the c-Myc.

Beyond the science it is important to highlight the ethical import of the Kyoto University team’s research programme.

It is well-known that embryonic stem cell research is easier and quicker because there is no need to rejuvenate cells since they are by definition embryonic. But in the case of human embryos such a solution implies not only manipulating something that is ethically inviolable but also killing the heart of those who accept it. It is much better and smarter as well as ethically acceptable to rejuvenate old cells. In the first case, there is death; in the second, regeneration.

It is also a consolation to find that the path chosen and tenaciously held by Yamanaka’s team is increasingly accepted in biotech institutions around the world, Italy included.

Carlo Alberto Redi, scientific director of the Fondazione Irccs-San Matteo in Pavia, stressed that “it is worth remembering that in 2001 that the Dulbecco Commission report, ordered by then Health Minister Umberto Veronesi, indicated that this was the way to go, insisting on the importance of funding genetic stem cell re-programming to avoid using embryos. As always in Italy funding remains a problem but this is a promising area of research.”

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