For the first time, researchers have disabled a gene in human embryos using CRISPR-Cas9 gene editing technology to determine the gene’s function, according to a study published in Nature on Sept. 20.
One of the most significant scientific advances in recent history, CRISPR-Cas9 technology, often referred to as just CRISPR, enables scientists to direct a specific DNA-snipping protein to cut a gene they select to disable or remove it. If a gene is removed, the scientists also have the ability to introduce a new gene in its place. In this study, the researchers disabled a gene called OCT4 and discovered it plays a previously unknown role in the development of the placenta. Dieter Egli, an assistant professor of Stem Cell Biology at Columbia University who was not a part of the research team, said being able to directly study the function of human genes like this is “unheard of.” Until now, he states, our knowledge of the roles of genes in human development has been “largely inferred from studies of mice, frogs and other model organisms” in which genes were deleted or disabled.
According to an article by Tina Hesman Saey published in Science News on September 20, Dr. Kathy Niakan, lead researcher of the study and a developmental biologist at The Francis Crick Institute in London, received approval from United Kingdom government regulators last year to conduct gene editing research on human embryos left over from in vitro fertilization treatments. She and her team practiced using the gene editing technology on mouse embryos and human stem cells for nearly a year before the study in order to optimize their technique.
The researchers focused on the OCT4 gene because it has been shown to play an important role in mouse embryo development and to help human embryonic stem cells retain their ability to transform into any type of cell. In fact, the OCT4 protein, produced by the OCT4 gene, has been used by scientists to reprogram adult cells to act similarly to embryonic stem cells, according to Saey. However, the researchers suspected the function of the OCT4 gene might be somewhat different in human embryos than in mouse embryos.
The study confirmed the OCT4 gene’s importance in embryonic development because embryos in which the gene was disabled were significantly hindered in their development. However, the study showed that disabling the gene also hindered the development of cells which typically become the placenta. Niakan said this role of the gene was not “predicted anywhere in the literature,” and added, “We’ll be spending quite a lot of time on this in the future to uncover exactly what this role might be.”
Other researchers have also used CRISPR to edit genes of human embryos, including groups in China and a group in the United States which earlier this year used the technology to repair mutated genes. None of the embryos from these studies were allowed to mature. CRISPR technology is in its early stages, having been developed only five years ago, and the FDA and NIH will not fund studies that propose using CRISPR on human embryos, in accordance with the FY16 appropriations bill which prohibits use of federal funds “in research in which a human embryo is intentionally created or modified to include a heritable genetic modification.”
However, private funding of such research is legal in the United States. For instance, the United States National Academy of Sciences will consider research proposals including CRISPR use on human embryos if the research addresses serious inherited diseases, according to their 2017 report Human Genome Editing: Science, Ethics, and Governance.
Abbey Bigler is a fourth-year English major with minors in business and technical writing, communication studies and biology. She can be reached at AB842693@wcupa.edu.