Stem cells (SC) are a population of cells that are the original precursors of all others. In the formed organism, they can differentiate into any cells of any organ, any cells of it can form in the embryo.
Their purpose in nature is the regeneration of tissues and organs of the body from the very beginning from its birth in various injuries. They simply replace damaged cells, renewing them and protecting them. Simply put, these are parts for the body.
How are they formed
The huge number of all cells of the adult body once begins with the fusion of the male and female reproductive cells during fertilization of the egg. Such a merger is called a zygote. All subsequent billions of cells arise during its development. The zygote contains the entire genome of the future person and its pattern of development in the future.
When it occurs, the zygote begins to actively share. First, cells of a special kind appear in it: they are only capable of transmitting genetic information to generations of new cells that arise further. These populations are the famous embryonic stem cells, around which there is so much excitement.
In the fetus, ESCs, or rather, their genome, are still at the zero point. But after switching on the specialization mechanism, they can be transformed into any demanded cells. Embryonic stem cells are obtained at an early stage in the developing embryo, now called the blastocyst, on the 4th-5th day of the life of the zygote, from its internal cell mass.
As the embryo develops, specialization mechanisms, the so-called embryonic inductors, are activated. They themselves already include the genes that are currently needed, from which different families of SC arise and the beginnings of future organs are outlined. Mitosis continues, the descendants of these cells already specialize, which is called committing.
At the same time, embryonic stem cells are able to transform (pass) into any germinal leaf: ecto-, meso- and endoderm. Of these, fetal organs subsequently develop. This property of differentiation is called pluripotency and is the main difference between ESCs.
SC classification
They are divided into 2 large groups - embryonic and somatic, obtained from an adult organism. The question of how embryonic stem cells are obtained and used is well understood.
Selected 3 sources of SC:
- Own stem cells, or autologous; most often they exist in the bone marrow, but can be obtained from the skin, adipose tissue, tissues of some organs, etc.
- SC from the placenta obtained during delivery from umbilical cord blood.
- Fetal SCs obtained from tissue after abortion. Therefore, donor (allogeneic) and their own (autologous) SCs are distinguished. Regardless of their origin, they have special properties that continue to be investigated by scientists. For example, they can remain viable and retain all their properties for decades with proper storage. This is important when collecting SC from the placenta during childbirth, which can be considered a form of health insurance and protection for the newborn in the future. They can be used by this individual when he develops a serious illness. In Japan, for example, there is a whole government program that ensures the availability of IPS cell banks in 100% of the population.
Examples of the use of SC in medicine
Stages of embryonic transplantation:
- 1970 - the first transplants of autologous SC are performed. There is evidence that in the former CCCP "youth vaccinations" were made to aging members of the Politburo of the CPSU several times a year.
- 1988 - SK was transplanted to a boy with leukemia who lives today.
- 1992 - Professor David Harris creates the UK Bank, where his first child was the first customer. His SKs were frozen first.
- 1996-2004 - 392 transplantations of own SC from bone marrow were performed.
- 1997 - donor SC from the placenta was transplanted to a Russian cancer patient.
- 1998 - they transplanted their SCs to a girl with a neuroblastoma (brain tumor) - the result is positive. Scientists also learned to grow SC in vitro.
- 2000 - 1200 transplantations were performed.
- 2001 - the ability of adult human bone marrow SC to transform into cardio and myocytes was revealed.
- 2003 - information was obtained on the preservation of all SC biological properties in liquid nitrogen for 15 years.
- 2004 - the world banks of the UK collections already have 400,000 models.
The main properties of ESC
Examples of embryonic stem cells are any primary leaf cells in an embryo: these are myocytes, blood, nerve cells, etc. ESCs in humans were first identified in 1998 by US scientists James Thompson and John Becker. And in 1999, the most famous scientific journal Science recognized this discovery as the third most important after revealing the DNA double helix and decoding the human genome.
ESCs have the ability to constantly renew themselves, even if there is no incentive to differentiate. That is, they are very plastic and their potential for development is not limited. This makes them so popular in regenerative medicine.
The so-called growth factors can serve as a stimulus for their development into other types of cells; they are different for all cells.
Today, embryonic stem cells are not allowed to be used as official treatment by official medicine.
What is used today
For treatment, only their own SCs from adult tissues are used, most often these are red bone marrow cells. The list of diseases includes blood diseases (leukemia), the immune system, in the long term - oncological pathologies, Parkinson's disease, type 1 diabetes, multiple sclerosis, myocardial infarction, strokes, spinal cord diseases, blindness.
The main problem has always been and remains the compatibility of SC with the cells of the body when they are introduced into it, i.e. histocompatibility. When using native SK, this issue is solved much easier.
Therefore, the question of which stem cells are preferable to use - embryonic or stem tissue, the answer is unequivocal: only tissue. Any organ has special niches in the tissues where SCs are stored and consumed as needed. The prospects for SC are enormous, because scientists hope to create from them, according to indications, the necessary tissues and organs instead of donor ones.
History of becoming
In 1908, Alexander Maksimov (1874-1928), professor and histologist of the St. Petersburg Naval Aviation Institute, noticed in the study of blood cells that they are constantly and fairly quickly updated.
A. A. Maksimov guessed that the problem here was not simply cell division, otherwise the bone marrow would be larger than the person himself. Then he called this predecessor of all stem blood elements. The name explains the essence of the phenomenon: in the red bone marrow there are special cells whose task is only in mitosis. In this case, 2 new cells arise: one becomes blood, and the second goes into stock - develops and divides again, again the cell goes into stock, etc. with the same result.
These constantly dividing cells make up the trunk, branches sprouting from it sideways - these are new professional blood cells that are forming. This process is continuous and amounts to billions of cells every day. Among them are groups of all blood elements - leuko and erythrocytes, lymphocytes, etc.
Subsequently, Maximov made his theory at the congress of hematologists in Berlin. This was the beginning of the history of the development of the UK. Cell biology became a separate science only at the end of the 20th century.
In the 60s, SK began to be used in the treatment of leukemia. They were also detected in the skin and fatty tissue.
Distinctive features of SK
Promising ideas do not exclude the existence of underwater reefs when they are put into practice. The huge problem is that the activity of SK gives them the opportunity to share in an unlimited number, and it becomes difficult to control them. In addition, ordinary cells are limited in division by the number of cycles (Hayflick limit). This is due to the structure of chromosomes.
When the limit is exhausted, the cell no longer divides, which means it does not multiply. In cells, such a limit varies depending on their type: for fibrous tissue, it is 50 divisions, for SK blood - 100.
Secondly, SCs do not ripen all at once simultaneously, therefore, in any tissue there are different SCs at different stages of maturation. The more normal the maturity of a cell, the less its retraining properties to another cell. In other words, the laid down genome for all cells is similar, and the mode of operation is different. Partially matured SCs, which upon stimulation can mature and differentiate, are blasts.
In the central nervous system, these are neuroblasts, in the skeleton - osteoblasts, skin - dermatoblasts, etc. External or internal causes serve as a stimulus for maturation.
Not all cells in the body have this ability, it depends on the degree of their differentiation. Highly differentiated cells (cardiomyocytes, neurons) can never produce their own kind, which is why they say that nerve cells do not recover. And poorly differentiated ones are capable of mitosis, for example, blood, liver, bone tissue.
Embryonic stem (ES) cells differ from other SCs in that the Hayflick limit does not exist for them. ESCs divide endlessly, i.e. they are virtually immortal (immortal). This is their second property. This property of ESC inspired scientists, it would seem, to use it in the body to prevent its aging.
So why has the use of embryonic stem cells not gone this way and is frozen? Not a single cell is guaranteed against genetic breakdowns and mutations, and they, when they appear, will be transmitted along the line further and accumulate. We must not forget that human embryonic stem cells are always carriers of foreign genetic information (foreign DNA), therefore they themselves can cause a mutagenic effect. That is why the use of their ICs is becoming the most optimal and safest. But another problem arises. SCs in the adult body are very few, and it is difficult to extract them - 1 cell per 100 thousand. But despite these problems, they are removed and autologous SCs are often used in the treatment of CVD, endocrinopathies, biliary pathologies, dermatoses, diseases of the musculoskeletal system, gastrointestinal tract, lungs.
More about ESA Reefs
After receiving embryonic stem cells, they must be directed in the right direction, i.e. manage them. Yes, they can practically recreate any organ. But the problem of choosing the right combination of inductors has not yet been resolved.
The use of embryonic stem cells in practice was at first ubiquitous, but the infinity of division of such cells makes them uncontrolled and is related to tumor cells (Kongheim theory). Here is another explanation for the freezing of work with ESCs.
ESC rejuvenation
A person loses his SC as he ages, their number is steadily falling, in other words. Even by the age of 20, they are few, after 40 years not at all. That is why, when in 1998 the Americans first isolated ESCs, and then cloned them, cell biology received a powerful impetus in its development.
There was hope for a cure for those diseases that were always considered incurable. The second line is injection rejuvenation with embryonic stem cells. But a breakthrough in this regard did not take place, because it is still not known exactly what SCs do after being introduced into a new organism. Either they stimulate the old cell, or completely replace it - they take their place and work actively. Only when establishing the exact mechanism of behavior of the SC can we talk about a breakthrough. Today, great care is required in choosing this method of treatment.
ESC and rejuvenation in Russia
In Russia, restrictions on the use of ESCs have not yet been introduced. Here, not serious research institutes are engaged in embryonic stem cell therapy for rejuvenation, but only ordinary cosmetology salons.
And one more thing: if in the West the test of the action of ESCs is carried out in laboratories on experimental animals, then in Russia new technologies are tested in humans by the same home-grown beauty salons. Booklets with all kinds of promises of eternal youth the sea. The calculation is correct: for those who have a lot of money and opportunities, it begins to seem that nothing is impossible.
Treatment with embryonic stem cells in the form of a minimum course of rejuvenation is only 4 injections and is estimated at 15 thousand euros. And despite the understanding that it is not worth blindly trusting technologies that are not scientifically proven, for many public persons the desire to look younger and more attractive outweighs the person starts to run ahead of the engine. Moreover, before my eyes are those whom it helped. There are such lucky ones - Buinov, Leshchenko, Rotaru.
But there are many more who are unlucky: Dmitry Hvorostovsky, Zhanna Friske, Alexander Abdulov, Oleg Yankovsky, Valentina Tolkunova, Anna Samokhina, Natalya Gundareva, Lyubov Polishchuk, Viktor Yanukovych - the list goes on. These are the victims of cell therapy. What became common to all of them was that, shortly before their condition worsened, they seemed to blossom and grow younger, and then quickly died. Why does this happen, no one can answer. Yes, when they enter an aging body, ESCs move cells to active division, a person seems to be getting younger. But this is always stress for an elderly organism, and any pathology can develop. Therefore, no clinic can give any guarantees about the consequences of such rejuvenation.