Nowadays there is a lot of talk about the cultivation of individual organs outside the body and their augmentation to replace the lost ones. But maybe there is a better way - just to restore or, in a scientific way, to regenerate your organs?
In principle, a person is partly endowed with this gift. Our cuts are healed by skin regeneration. The blood is also regenerated. But I want more. Moreover, not only ordinary people dream about this, but also scientists.
For example, the staff of the Laboratory of Regeneration Problems of the Institute of Developmental Biology of the Russian Academy of Sciences, headed by Doctor of Biological Sciences Viktor Mitashov, has long been developing various methods for restoring human bone and nerve tissues, and more recently the retina. In general, lower organisms are more often capable of regeneration than more highly organized ones.
For example, among invertebrates there are many more species that are able to restore lost organs than among vertebrates, but only some of them can regenerate a whole individual from a small fragment of it. Such primitive animals as ctenophores and rotifers are practically incapable of regeneration, while in much more complex crustaceans and amphibians this ability is well expressed.
Many would like to get themselves regeneration like Wolverine, the hero of American comics. It can heal even the worst wounds in minutes.
The ability of sponges to regenerate is especially amazing. Scientists have set up an unusual experiment; pushed the body of an adult sponge through the mesh tissue and separated all the fragments formed from each other. It turned out that if you then put these small pieces in water and mix well, completely destroying all the bonds between them, then after a while they will begin to gradually converge and eventually reunite, forming a whole sponge, similar to the previous one. This involves a kind of "recognition" at the cellular level.
Another regeneration record holder is the tapeworm, which is able to recreate a whole individual from any part of its body. It is theoretically possible, by cutting one worm into 200,000 pieces, to obtain as many new worms from it as a result of regeneration. And from one ray of a starfish, a whole star can be reborn.
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But another example is much more famous - lizards, which grow their own tail, and newts, which can regenerate eyes, legs and tail up to six times.
Alas, a person is deprived of this priceless property. Could modern science help us to master the corresponding mechanisms?
In terms of human life, a restoration process similar to Triton's could take us only six months. However, it is very difficult to figure out how a newt restores an eye in a month. Scientists cannot yet repeat his exploits. But it has already become clear how he and others like him do it.
Let's start from the very beginning - with the birth of the organism. It is known that in the course of embryonic development, cells of any multicellular organism undergo specialization. From some, for example, legs are obtained, from others, say, muscles, gills or eyes. The so-called Doh-genes give the command to both the whole body and specific organs to develop according to a certain plan - so that it does not happen that the eye grows where the leg should be.
The Drosophila fly has 8 Dox genes, the frog has 6, and the human has 38. And it turned out that during regeneration, the newt "remembers" its embryonic past, including a genetic program that activates the Dox genes and restores deleted or damaged tissues and organs …
But an eye or a tail must arise from something - it cannot be regenerated from the air. The body has two ways - to gain new cells, new building material, or to use what is left after the loss of an organ.
It turned out that nature uses both of these methods. Embryonic stem cells are the building blocks for regeneration. This is the name of the cells of the embryo, which in their development simply did not grow to the stage of specialization and, therefore, are capable, under the influence of certain factors, to turn into cells of various tissues and organs of more than two hundred types.
Moreover, during regeneration, the “old” cells of the newt, through complex manipulations, turn into similar to embryonic ones. A lot of controversy has been associated with them lately. The fact is that for scientists, the main source of embryonic stem cells is human embryos. Biologists are enthusiastically studying the properties of embryonic stem cells: if successful, these cells will open up completely new possibilities in surgery and ensure the restoration of certain organs. If as a result of the disease some groups of cells fail, even if highly specialized, then it will be possible to replace them.
And our biologists are not at all in the last role in these works. For example, Academician of the Russian Academy of Natural Sciences Leonid Polezhaev has been dealing with the problem of the regeneration of the bones of the cranial vault for decades. First, he managed to achieve the regeneration of the skull bones in dogs and rats. Then, together with doctors from the Institute of Neurosurgery named after N. N. Burdenko of the USSR Academy of Medical Sciences tried to restore the skull bones in patients with head injuries.
In this case, bone sawdust was used, which "induced" the bones of the human skull to regenerate. As a result, the area of injury was completely covered with new bone. More than 250 operations have been performed using this technique.
Recently, a group of scientists from the University of Tokyo led by Makoto Asashima cultivated thousands of embryonic stem cells in a special solution of vitamin A, varying the concentration of the vitamin. A low concentration activates genes that control the development of ocular tissue, while a high concentration triggers the genes responsible for the formation of the organ of hearing.
Makoto Asashima stated that a whole frog eye could be obtained in five days. In a similar, but simpler method, new buds were previously grown and successfully transplanted into the frog. The recipient animal survived for a month after this operation.
And experts from the Keio University of Tokyo have published a report on a successful experiment on the use of human embryonic stem cells to repair damaged spinal cord tissue in monkeys. According to the head of the work, Professor Hideyuki Okano, the original stem cells were taken from a deceased human embryo with the consent of the parents and the approval of the university ethics council.
Then these cells were multiplied in a nutrient medium and planted in five monkeys (10 million cells each), whose forelimbs were immobilized as a result of a spinal injury. In one primate, all musculoskeletal functions returned to normal after two months, while the rest of the recovery process continues.
In the laboratory of Viktor Mitashov, experiments on the restoration of the newt's eye were successfully carried out. And now researchers are preparing for experiments on growing the human retina.
But experts speak carefully about the possibility of growing a whole eye. They can be understood: the evolutionary gap between the newt and man is too great. The nose on the other hand, the mechanisms of development of organs are similar, so there is a hope that someday biologists will be able to force an injured person, "falling into childhood", to grow the necessary organs - teeth, instead of those that have fallen out, new cells of the liver, kidneys, pancreas, new muscle tissues for a heart affected by myocardial infarction.