Signals Blog


Last month, Nature published a comment by Edward Lanphier and colleagues, which foreshadows the publication of a study in which scientists have used new genome editing tools to modify the DNA of human embryos. Author David Cyranoski weighed in, suggesting that scientists were divided on where the ethical boundaries for such a technology existed. Science magazine soon followed suit and published an entire collection on the technology, including a lovely Insight article, by first author David Baltimore, Nobel laureate and world leading expert in recombinant DNA research.

Clearly, the debate is raging on how far to push this relatively new technology and international societies of researchers have a duty to help guide decision-makers regarding the potential impacts in their fields. This post is about the immediate and considered response of the International Society for Stem Cell Research (ISSCR) on the possibility of germline editing in clinical applications.

But first, the science. For those curious about the technology itself, using a technique dubbed “CRISPR”, researchers can now selectively remove and modify pieces of the genome in a highly efficient manner.

An excellent editorial was published in Nature Biotechnology, earlier this month, explaining CRISPR-Cas genome editing and the concomitant technological strides being made in the fields of genetics and disease modeling. Essentially, bacteria have a system to recognize foreign genetic material and cut up the foreign DNA in a highly selective manner, and the major breakthrough is the adaptation of this system to selectively target areas of the genome.

While the system holds much promise for future therapies and for making research of gene function easier, there are still many unknowns. These include poor characterization of the genome-wide effects of using CRIPSR-Cas and unknown off-target effects of the system that relies on DNA similarity. Taken to the extreme, such off-target effects could result in a cell acquiring new mutations as a result of CRISPR that gives cells a proliferation advantage and develops into cancer. Applied to the germ line (e.g., the egg and sperm) where changes could be inherited, the potential consequences are far-reaching.

Enter the ISSCR, which in my opinion has been an exemplary organization for engaging with the public as a scientific society, especially in the highly controversial fields of stem cell biology and regenerative medicine.

The ISSCR’s previous track record on similar issues is very strong: their Closer Look at Stem Cells helps patients navigate the very tricky world of stem cell therapies, and ISSCR has also published guidelines on the ethical use of embryonic stem cells and clinical trials involving stem cells.

Granted, many areas of science are not nearly as contentious as stem cell biology and the ISSCR’s public outreach was borne from need rather than altruism as a consequence of the stem cell research bans in the United States. Still, the ISSCR’s model and role in public debate is admirable, and it continues to guide discussion in government and scientific settings.

Just a week after the Nature editorial on genome editing, the ISSCR came to the fore issuing a statement to its members and the international community. It is a clear recommendation to keep genome editing tools that impact the germ line far away from the clinic for the time being, and possibly forever, should the ethical and societal implications be deemed too risky.

“The International Society for Stem Cell Research calls for a moratorium on attempts at clinical application of nuclear genome editing of the human germ line.”

Almost more important, the ISSCR leadership recognizes the limitations of science and scientists, asserting that: “Scientists currently lack an adequate understanding of the safety and potential long term risks of germline genome modification” and calls for broad public and international dialogue from all sectors of society.

As a stem cell researcher, I find this sort of leadership inspiring. It is focused on the real world implications of research, rather than pursuing a technology at all costs. Scientists can be sheltered from such debates in their respective areas of research and the consequences of such myopia can be far reaching. The ISSCR helps the public and its membership understand and deal with such issues and should be commended. I would love to see more scientific societies behave similarly. I would also love to know what our readers think. Please leave your comment below.

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David Kent

David Kent

Principal Investigator at University of Cambridge
Dr. David Kent is a Principal Investigator at the University of Cambridge in the Cambridge Stem Cell Institute ( His laboratory's research focuses on fate choice in single blood stem cells and how changes in their regulation lead to cancers. David is currently the Stem Cell Institute’s Public Engagement Champion and has a long history of public engagement and outreach including the creation of The Black Hole in 2009. He has been writing for Signals since 2010.