Researchers call for greater awareness of unintended consequences of CRISPR gene editing

Researchers from the Francis Crick Institute have revealed that CRISPR-Cas9 genome editing can lead to unintended mutations on the targeted portion of DNA in early human embryos. The work highlights the need for greater awareness of and further investigation into the effects of CRISPR-Cas9 genomic care, especially when used to edit human DNA in laboratory research.

CRISPR-Cas9 genome editing is a widely used research tool that allows scientists to remove and replace parts of DNA in cells so that, for example, they can study the function of a given gene or repair mutations. Last year, the Nobel Prize in Chemistry was awarded to the researchers who developed CRISPR-Cas9.

In their study, published in PNAS, Crick scientists retrospectively analyzed data from previous research where they studied the role of the OCT4 protein in human embryos during the first few days of development.

The team found that although the majority of CRISPR-Cas9-induced mutations were small insertions or deletions, about 16% of the samples were large unintentional mutations that would be missed by conventional methods of determining DNA changes.

Research is ongoing to understand the exact nature of the changes on the target areas, but this may include the removal of parts of DNA or more complex genomic rearrangements.

The discovery highlights the need for researchers using CRISPR-Cas9-mediated genome care to edit human cells, whether somatic or germ lines, should be aware of these potential unintended consequences and be able to test them. This is even more important if they hope that their work will be used clinically, as unintended genetic changes such as these can lead to diseases such as cancer.

“Other research teams have reported these types of unintended mutations in human stem cells, cancer cells, and other cellular contexts, and now we’ve detected them in human embryos,” said Professor Kathy Niakan, group leader of the Human Embryo and Stem Cell Laboratory. at the Francis Crick Institute and Professor of Reproductive Physiology at the University of Cambridge, and senior author of the study.

“This work emphasizes the importance of testing these unintended mutations to understand exactly what changes have occurred in any human cell type.”

The Crick researchers developed an open source computational pipeline to determine if CRISPR-Cas9 caused unintended mutations on the target based on different types of next-generation data.

“We and others are trying to develop the tools to assess these complex mutations,” Niakan added.

“It is important to understand these events, how they occur and their frequency, so that we can appreciate the current limitations of the technology and inform strategies to improve it in the future to minimize these mutations.”

Gregorio Alanis-Lobato, lead author and former postdoctoral fellow in Crick’s Human Embryo and Stem Cell Laboratory, says: ‘Conventional tests used to verify the accuracy of CRISPR-Cas9 can target the type of unintended mutations miss identified in this study. There is still so much for us to learn about the implications of CRISPR-Cas9 technology. Although this valuable tool is refined, we must thoroughly examine all changes. ”

There are important ongoing debates around the safety and ethics of using CRISPR-Cas9 genomic care on human embryos for reproductive purposes. And in 2019, there was international condemnation of the work of a researcher in China who edited embryos that led to the birth of twins. In the United Kingdom, its use on human embryos is strictly regulated and is only allowed for research purposes. Research is limited to the first 14 days of development and embryos may not be implanted in the uterus.

The data for this work relate to embryos previously studied by the Crick’s Human Embryo and Stem Cell Laboratory. The embryos were in the blastocyst stage of early development, consisting of about 200 cells. They were donated to research by people who underwent in vitro fertilization (IVF), and were not needed during treatment.

The research was led by scientists at the Francis Crick Institute, in collaboration with fellow professor Dagan Wells at the University of Oxford. Kathy Niakan is future director of the University of Cambridge’s Center for Trophoblast Research, and chair of the Cambridge Strategic Research Initiative in Reproduction.