One of the most amazing mysteries of biology,protected by nature itself - the processes during the development of the embryo. They are hidden from prying eyes, as they occur in the body of the mother. However, now Israeli scientists at the Weizmann Institute seem to have found a way to study the mechanisms of fetal development in more detail. To do this, they created artificial mouse embryos. The most unusual thing about all this is that the embryos were created from stem cells, that is, without sperm, eggs and fertilization. But that's not all - artificial embryos have shown the ability to live for quite a long time and develop anatomy that is fully consistent with the natural one. Scientists have not been able to achieve anything like this before.
What is the difficulty of creating artificial embryos
Earlier, we have already said that scientists were able togrow artificial human and monkey embryos. However, it was obtained by editing the genes of the monkey embryo. That is, it was not the creation of an embryo from scratch. In addition, the scientists grew individual organelles and observed their development. In particular, thanks to this, it was possible to find out that the intestine affects the development of the heart.
However, to create a full-fledged artificial embryofrom stem cells, which would fully and correctly develop, did not work. At some point, their development stopped - the cells began to specialize, but the organ system did not form. In this case, the embryos lived no more than a few days. Now, scientists have managed to overcome this “wall”, as reported in the journal Cell.
“The right cells began to appear at the right time,” says biologist at the Leiden University Medical Center, Nils Geisen.
Thanks to this achievement, Israeli scientistswill be able not only to study the processes that occur during the development of the embryo, but also to understand why birth defects occur. Moreover, the head of the study, stem cell biologist Professor Jacob Hanna, hopes to create an embryo from human stem cells in the future.
How scientists created artificial embryos
Last year, Jacob Hanna with his colleaguesdeveloped the technology for growing mouse embryos. She allowed the fetuses to live outside the mother's body for a record 11 days. For understanding, this is more than half the gestation period of mice. A mechanical uterus helped to achieve this result. The device resembles a wheel with bottles in a circle. Embryos rotate inside bottles filled with nutrient fluid and growth factors. The installation not only provides optimal conditions for the development of embryos, but also allows you to accurately track the level of oxygen, as well as other vital signs.
Previously, the team had grown embryos fromby fertilizing mouse eggs. This time, the challenge was to obtain embryos from embryonic stem cells. To do this, scientists mixed them with genetically modified stem cells, which were supposed to develop into a placenta or yolk sac. That is, genetically modified cells had to change in tissue outside the fetus to support its growth. However, some stem cells have not been mixed with genetically modified cells.
Most stem cells failedform embryonic structures, but about 0.5% of the cells still coalesced into small balls. After that, on the fifth day, the scientists transferred the clusters of cells from the culture dishes to a mechanical uterus, where they continued to develop.
By the eighth day, the “embryoids” began to resemble8.5 day old natural embryos. Separate tissues and organs began to appear in them. As the authors of the work note, the embryos had a beating heart, tail ends, as well as segments that subsequently turn into skeletal muscles. Moreover, scientists have discovered a developing brain and spinal cord, as well as the rudiments of other organs.
In general, artificial embryos were practicallyidentical to natural. The researchers measured gene activity in more than 40,000 embryoid cells. It turned out that all the expected cell types were in the right places and appeared at the right time. The similarity with natural embryos was 95%.
Is it possible to create animals and humans from artificial embryos?
As the authors themselves say, artificialthe embryo could not develop into a full-fledged animal. For unknown reasons, the embryos stopped developing on the eighth day. Scientists will continue the study, and hope to overcome this barrier. But, in any case, a serious breakthrough has already been made in the field of growing artificial embryos.
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According to the researchers, this work will helpreduce the number of animal experiments. In addition, these developments will help pave the way to sources of cells and tissues for transplantation. For example, bone marrow cells can be used to treat leukemia patients. Thus, initially there is no task to create artificial animals or people from artificial embryos.