Should We Use CRISPR to Edit Human Embryos?

September 28, 2015 | Sarah Tse

Human embryo, 9-10 weeks after conception
Photo credit: lunar caustic/Flickr/CC BY-SA 2.0

British scientists want to use this powerful tool for genetic engineering on human embryos, but the road ahead is fraught with ethical and safety concerns.

The controversy over using genetic engineering techniques on human DNA rages on with a development now from Britain. Last week, scientists at London’s Francis Crick Institute applied for permission from the UK Human Fertilization & Embryology Authority to use the CRISPR/Cas9 system on viable human embryos.

CRISPR/Cas9 has been blowing up the world of genetics for the past few years, ever since it was first discovered as a naturally-occurring defense mechanism used by bacteria. The tool offers far more precision than any previously used techniques, and importantly for labs, it generates genetically-altered mice and other organisms much more quickly. CRISPR also ensures that the organism will receive those edits within a single generation. In addition to mice, scientists have successfully used the system in fruit flies, zebrafish, and even monkeys. The innovations using this system just keep rolling in, from suppressing HIV-related genes to breeding Parkinson’s-resistant minipigs.

SEE ALSO: Genetically Engineered Pests: Ultimate Solution or Too Much Power?

But such a powerful tool has naturally inspired fear of unforeseen repercussions. Last spring, leading scientists published several editorials urging caution after Chinese researchers made the first attempts to manipulate genes in human embryos. The experiment was a resounding failure — only four of the original 86 embryos took up the desired change in the gene for hemoglobin, and most cells in each of those embryos remained unchanged. Along with the targeted mutation, the four embryos also acquired several potentially harmful mutations.

Although the experiment only used nonviable embryos that would have been discarded otherwise, scientists from around the world still took up arms. The NIH decided to withhold funding from any research seeking to edit human embryos, even as other scientists expressed opinions about working on nonviable human embryos for basic research.

But now the trend appears to be reversing. If the scientists from the Francis Crick Institute receive permission to use CRISPR/Cas9, they plan to use their research to better understand which genes are crucial for human development. This new knowledge could improve techniques for in vitro fertilization and treatments for infertility. The precise alterations enabled by the CRISPR/Cas9 system would make their research more efficient, and hopefully use up fewer embryos. They also intend to limit their experiments to embryos donated by informed consent and surplus to IVF treatment.

Furthermore, an international group of stem-cell researchers, policymakers, and bioethicists, called the Hinxton Group, has publicly supported CRISPR/Cas9 research on human embryos as long as it’s used for basic research and clinical uses, rather than creating “designer offspring.”

The issue continues to ignite debates over bioethics and safety. The Chinese Academy of Sciences, Britain’s Royal Society, and the U.S. National Academy of Sciences plan to host an international summit in Washington on December 1-3 to discuss gene editing. Hopefully, the conversation will tackle all the hopes and fears associated with the future of human gene editing.

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