Human Embryos Can Now Be Developed In The Lab Past 14 Days After Historic Guideline Change

Scientists will now be able to grow human embryos for longer than 14 days after the International Society of Stem Cell Research (ISSCR) has updated their guidelines. The "14-day rule", which has been in place since the late 1900s, was designed to prevent researchers from developing embryos past the point in which a visible line of cells begins to form, but significant strides in research have meant that relaxing this rule is necessary to further developmental research. Each case will now be subject to rigorous ethics review and approval before researchers are allowed to continue the growth of an embryo.

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While the study of human embryos is steeped in controversial debate, researchers believe relaxing the guidelines is important to understand developmental issues that arise past the 14-day mark

“New scientific approaches are continuing emerge in all areas, but notably around stem cell science. Some of these emerging technologies present ethical challenges, even when the benefit to human health may be the long term objective,” said Professor Melissa Little, Chief Scientist, Murdoch Childrens Research Institute and incoming President of the ISSCR, in a statement.

“This is particularly so in research modelling the human embryo and generating human-animal chimeric tissues. The fact that these guidelines have been developed by the research community itself indicates a deep sense of responsibility and integrity and an active desire to ensure that the science is in step with the community.”

The 14-day rule is one of the most widely adopted medical rules in history, with almost every country in the world implementing it into their guidelines. It came into effect following the introduction of in-vitro fertilization (IVF), where the ability to develop human embryos within lab settings for research and fertilization changed developmental biology. Around the 15-day mark, a structure called the "primitive streak" develops across the back of the embryo, which is a line of visible cells that marks the beginning of gastrulation (formation of multiple layers of cells). This was deemed an obvious point in which to stop further research, and the guidelines were accepted throughout research committees.

However, as technology has progressed, it has become evident that many defects leading to miscarriage or permanent health conditions begin past the 14-day mark. As such, a review of these guidelines was called for and the ISSCR deemed it necessary to loosen the reigns.

Now, researchers are confident the relaxed guidelines will have a beneficial effect but want to ensure that regulatory bodies are able to continue to ensure ethical considerations are met.

“With advances in the development of stem cell-based therapies, the creation of tissue combining human and animal cells is needed to prove the value of such treatments before moving to man. This also presents ethical challenges that must be considered,” said Professor Little.

“With advances in gene editing, there is the prospect of delivering genetically modified cells. While this brings great promise of new treatments, it is also important to have such research monitored and approved. In all instances, the Guidelines outline where a technology has potential to do good but must have regulatory oversight.”

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