Let the sheep 's muzzle…
Scientists have obtained chimeric sheep embryos with human cells for the first time
Natalia Pelezneva, Naked Science
Biologists have managed to obtain embryos based on sheep cells and human stem cells. In the future, the technology is planned to be used for growing donor organs in animal bodies for transplantation.
For the first time, American researchers managed to create chimeric embryos based on sheep embryos containing human cells. In the future, this technology will allow to grow full-fledged human organs suitable for transplantation in the bodies of animals. The development was discussed at the annual conference of the American Association for the Advancement of Science in Austin (Pablo Ross, Towards Xenogeneic Generation of Human Organs).
Chimeras are organisms consisting of genetically heterogeneous cells. In this case, stem cells obtained from the human body are injected into the embryo of a sheep. With the help of genetic engineering technologies, the genes associated with the development of a certain organ – the one that is later planned to be transplanted - are "turned off". Then the chimeric embryo is transferred to the uterus of an adult animal, where it develops in the same way as an ordinary embryo. As a result, it is planned to get a chimera, in which one necessary organ will consist entirely of human cells. In 2016, a similar technology was tested on pig embryos in which human pancreatic tissue was grown. The experiment lasted 28 days.
The experiment with sheep embryos was the next step towards such a transplant. Now one of the 10,000 cells of the resulting embryo is human, in the future scientists plan to increase the number of human cells in chimeric embryos to 1%. When this ratio is achieved, it will be possible to proceed to longer experiments. In the new experiment, the development of embryos was also observed for 28 days, 21 of which the embryos spent in the body of an adult sheep. The following experiments can last up to 70 days.
According to the researchers, fewer embryos are required for the efficient transfer of embryos into the body of a sheep than in the case of pigs. About 50 embryos were transferred into the body of one pig, four are enough for an experiment with a sheep.
Experiments with chimeras are often criticized: according to opponents, it is not known whether human cells migrate into the brain of an animal – this would violate ethical norms. The authors of the new work say that this is unlikely: very few human cells get into embryos, while changes can always be tracked and the experiment stopped.
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