In the new edition

Stem cell researchers have recognized experiments on human embryos after 14 days as permissible

Polina Loseva, N+1

The International Society for Stem Cell Research has released an updated version of ethical guidelines for experiments with human cells and embryos. Many technologies, including growing human embryos in the uterus of animals, as well as cloning and genetic editing of humans, remain banned. The indulgences affected the cultivation of embryos in vitro: if it was previously considered unacceptable to grow them for longer than 14 days of development, now there is no upper limit, and the decision is left to the discretion of local ethical commissions. A new version of the recommendations is published on the website isscr.org .

Recently, we often write about news from the world of embryology and reproductive technologies. Mouse embryos grow outside the mother's body, a human muscle develops inside a pig embryo, human and monkey cells combine into one chimera, and a full-fledged human embryo can now be obtained from one cell of an adult organism.

All these experiments raise a lot of questions and doubts — both technological and ethical. The further the methods of embryology develop, the higher the risk that scientists will be able to accidentally cause pain to a developing organism. Therefore, in some countries there are laws that regulate experiments on embryos. There are no legal restrictions in other countries, but each study must be approved by the ethics committee, and it, in turn, relies on the standards of the scientific community, which are traditionally formulated by the International Stem Cell Research Community (International Society for Stem Cell Research).

Until recently, these regulations were based on a decision taken by the UK government in the mid-1980s. Then scientists, lawyers and bioethicists agreed to limit experiments on embryos to 14 days after fertilization.

But a lot has changed since then: not only our ideas about how the human embryo develops and from what moment it can feel pain, but also the technical capabilities of embryologists. If in the 1980s scientists were able to grow embryos in vitro no longer than the first week of development, now there are technologies that allow them to be cultivated for at least two weeks (and it is forbidden to check what will happen next). Therefore, many researchers have proposed updating the agreement and moving the deadline for growing embryos. And ISSCR has released a new version of the recommendations.

ISSCR suggests dividing the whole range of possible manipulations with human embryos and their derivatives into three categories. The first includes experiments that do not require special approval by ethical and scientific committees. This is working with individual stem cells, including progenitors of germ cells, as well as organoids. Even the organoids of the nervous system were considered safe by experts — in their opinion, there are no arguments yet in favor of the fact that the cellular model of the brain can feel pain and even more so be aware of itself. In the same category were models of parts of embryos collected from stem cells, as well as chimeric embryos (from humans and other animals) — provided that they are kept in culture in vitro and not planted in the uterus of the animal.

The second category includes experiments that require the approval of a special commission of scientists, bioethicists, lawyers and members of the public — it must assess the scientific validity and ethical acceptability of the study. Such approval, according to the new recommendations, will be needed, among other things, for:

• Creation and cultivation of human embryos in vitro for research purposes;
• Genetic modification of embryos or germ cells;
• Transplanting human cells into an animal embryo, which is then carried in the animal's uterus;
• Creation of full-fledged embryo models;
• Insertion of the embryo into the human uterus after mitochondrial transfer.

In the third category, ISSCR experts attributed experiments that they would have banned. However, they are ready to resolve some of them later — when and if it is proved that it is safe: This is the use of germ cells derived from stem cells to create embryos and edit the nuclear and mitochondrial genome of embryos (which will then grow into children). Experts considered other studies unjustified from a scientific point of view and ethically questionable. This forbidden list includes:

• Growing chimeric embryos in the uterus of a human or monkey;
• Cultivation of chimeras producing human germ cells;
• Implanting model human embryos into the human uterus;
• Planting of any human embryos into the uterus of an animal;
• Human cloning (with the exception of therapeutic — the cultivation of individual organs and tissues).

Thus, instead of moving the border from the 14th day of development, the international scientific community actually canceled it. Now it will be up to experts on the ground to decide from what point the embryo should be considered sensitive and humanoid enough to prohibit experimenting with it.

Portal "Eternal youth" http://vechnayamolodost.ru