Posted 26 августа 2022, 14:23
Published 26 августа 2022, 14:23
Modified 24 декабря 2022, 22:37
Updated 24 декабря 2022, 22:37
In early August, many world media, including Novye Izvestia, reprinted and commented on the sensational news that appeared in the scientific publication Cell , that scientists from the Weizmann Institute in Israel used mouse stem cells to form embryo-like structures in the initial stages without fertilization process. In less than a week, scientists had embryonic-like structures with a rudimentary heartbeat, circulating blood, a brain, and an early-stage gut. At the same time, compared with natural embryos, synthetic ones were 95% the same in terms of their internal structure and genetic structure of cells.
True, so far synthetic embryos cannot yet develop in the wombs of living animals: when they were transplanted into the wombs of female mice, they died.
However, the scientists expect that their discovery will contribute to a deeper understanding of how organs and tissues are formed during the development of natural embryos. “The embryo is the best organ production machine and the best 3D printer,” said project leader Professor Jacob Hanna from Israel.
The success of Israeli scientists was just the other day repeated by a group of biologists from the University of Cambridge and the California Institute of Technology, led by Magdalena Zernika-Goetz . They also “persuaded” mouse stem cells to grow into synthetic embryos, which began to develop hearts and brains like real ones.
Lab embryos created without any eggs or sperm and incubated in a device resembling a rapidly spinning Ferris wheel full of tiny glass bubbles survived for 8.5 days. This is almost half the duration of a normal mouse pregnancy. During this time, a yolk sac developed around the embryos to provide nutrition, and the embryos themselves developed a digestive tract; neural tubes, or rudiments of the central nervous system; beating heart; and a brain with well-defined subsections including the forebrain and midbrain, the scientists reported in a study published Aug. 25 in the world's leading scientific journal Nature .
The new work produced results very similar to those obtained by Jacob Hanna's group.
“This period of human life is so mysterious that being able to see how it happens, to have access to individual stem cells, to understand why so many pregnancies fail and how we could prevent it, is something special,” said Zernika-Goetz. .
Simply put, the purpose of this incredible discovery is not to create babies outside the womb, but to produce donor organs for people.
However, the ethical issues that inevitably arise from this experiment cannot be avoided. Therefore, the discovery of scientists excited users of social networks. They are sincerely happy:
- It's really cool. I think life expectancy will increase several times!
- The Jews have so many genetic diseases due to inbreeding that it remains only to give birth to children in this way. To the remaining 5% finished off the nation completely. Whoever starts to compete with the Creator is doomed! Children are God's work! Evidence of this IVF. There are a lot of sick children. Unfortunately...
But the most common comment was:
“ I wonder if there will be a soul in such a set ?”
For example, the analyst of the Nebozhena channel recalls that there is already a startup called Renewal Bio, which offers to copy you for cloning into a similar embryo, so that later it can be disassembled into spare parts for you. In fact, this is a 3D bioprinter, only many times cheaper and easier, because now such printers can only grow simple tissues, like cartilage or bones, but we still don’t know how to create something more complex. Summed up the liver or kidney - got the liver from the twin. Burned - transplanted his own skin.
Scientists are already working on the technology and eventually want to create an artificial model of human embryos that will be the equivalent of a 40-50 day pregnancy, just at this stage the main organs and tiny limbs, such as fingers, are formed. At this point, for example, fetal blood cells can be harvested, expanded, and transplanted into an elderly person to reboot their immune system. Or here's another fierce concept - to grow an embryonic copy of a woman with age-related infertility, then collect the ovaries from the copy, which can "ripen" in the laboratory or immediately in the original woman by transplantation. At the moment, all the works of this startup are classified as "secret", the site https://www.renewal.bio/ is a regular business card without much information.
Sounds exciting, but I'm interested in something else. If a child can be created without eggs and sperm, then the family in the usual model is not needed ... "
But the biologist and science journalist Irina Yakutenko lowers the degree of emotions, explaining what this experiment really consisted of, and how far scientists are still from creating a full-fledged living creature in a test tube. And therefore, it is too early to ask ethical problems now:
“As usual in such cases, the rumors about the event far outweigh its real significance. Although the experiments carried out are really important for developmental biology and research in the field of embryogenesis. Let's figure out what happened.
The papers present the results of long-term experiments on growing mouse embryos derived from stem cells outside the uterus. This is not the first such work, this is the coverage of another intermediate result. The source from which the embryo develops is embryonic stem cells, that is, cells obtained from a real embryo and theoretically capable of turning into all the tissues and organs necessary for a mouse. But these amazing transformations occur only in the uterus of a pregnant mouse, in vitro, that is, in a test tube, it is not possible to direct the development of these cells so that they form a functional embryo.
The research, published in early August, is another step towards replicating natural embryogenesis in the laboratory. Until now, through various tricks, scientists have been able to grow cells to a structure resembling a mouse embryo 7 days old. The new results describe the development of such an artificial embryo up to the stage of 8.5 days, and the entire mouse pregnancy lasts 20. The structure grown by scientists partially formed some regions of the brain, the heart began to beat, and the early stages of the formation of the intestinal and neural tubes passed. And although such an artificial embryo looks almost like a real one, the key word here is “almost”. Scientists describe a number of discrepancies between the real and in vitro embryos, and although they seem minor, at later stages such initial differences can lead to deformities or even prevent the embryo from forming at all. Actually, this is what happened: on the 9th day, the development of the embryo stopped, and, for example, the heart no longer looked just big, but disproportionately huge.
Although it seems to some that in order to repeat all the stages of pregnancy, it is enough to place the original cells in a suitable incubator, in reality everything is much, much more complicated. The start, development and stop of all stages of embryogenesis are controlled by a multistage system of signals and mutual influences. Including the role is played by surface tension and pressure, which are experienced by certain parts of the emerging embryo in the uterus. So just a bucket of nutrient solution, as shown in science fiction films, is not enough: scientists need to at least partially reproduce the uterus. This is what has been done in the published works. Starting from the fifth day, the embryos developed in a rotating glass vessel, and some of the original stem cells were directed along the path of formation of the so-called extra-embryonic tissues, that is, roughly speaking, the structures of the placenta. If anyone did not know, it consists partly of the cells of the mother, partly of the cells of the fetus.
Next, scientists plan to continue their experiments and bring mouse embryos to later stages of development. There are several answers to the reasonable question why this is all necessary.
First : by reproducing embryogenesis, researchers will be able to better understand its mechanisms and, perhaps, find ways to move in order to save at least some of the missed pregnancies.
Second : the embryo is the best donor of stem cells and organs. The idea that a new heart or kidney can be grown separately is most likely utopian: in real organisms, organs do not form on their own, but together, and their development is inextricably linked with the development of the whole organism.
Finally, the third answer, futuristic, is that, thanks to such work, sometime in the future, people will learn to grow new people or animals completely outside the body.
Obviously, the last two answers inevitably raise a lot of ethical questions. So far, society prefers to simply turn away from them, but in the future, perhaps not far away, they will still have to be addressed. And the automatic “No, never” solution that many come up with today is a solution of the past, not of the future. Approximately so approximately always it was offered to solve approximately all new questions. Perhaps understanding this will allow us to quickly overcome the expected slippage and move on to a constructive dialogue ... "