Stem cells (SCs) are a population of cells that are the original precursors of all others. In a formed organism, they can differentiate into any cells of any organ; in an embryo, they can form any of its cells.
Their purpose by nature is the regeneration of tissues and organs of the body initially from birth with various injuries. They simply replace damaged cells, renewing them and protecting them. Simply put, these are spare parts for the body.
How they form
A huge number of all cells of an adult organism once begins with the fusion of the male and female reproductive cells during the fertilization of the egg. This fusion 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 development scheme in the future.
When it appears, the zygote begins to actively divide. First, cells of a special kind appear in it: they are only capable of transmitting geneticinformation to subsequent generations of new cells. 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 turning on the mechanism of specialization, they can be transformed into any demanded cells. Embryonic stem cells are obtained at an early stage of the developing embryo, now called the blastocyst, on the 4-5th day of the zygote's life, from its inner cell mass.
As the embryo develops, the mechanisms of specialization, the so-called embryonic inductors, come into play. They themselves include the genes needed at the moment, from which different families of SCs arise and the beginnings of future organs are outlined. Mitosis continues, the descendants of these cells are already specialized, which is called comitation.
At the same time, embryonic stem cells are able to transform (transfer) into any germ layer: ecto-, meso- and endoderm. Of these, the organs of the fetus 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.
3 SC sources selected:
- Own stem cells, or autologous; most often they exist in the bone marrow, but canbe obtained from skin, adipose tissue, tissues of some organs, etc.
- SC from the placenta, obtained during childbirth from cord blood.
- Fetal SCs obtained from tissues after abortion. Therefore, donor (allogeneic) and own (autologous) SCs are also distinguished. Regardless of their origin, they have special properties that continue to be explored by scientists. For example, they can remain viable and retain all their properties for decades if properly stored. This is important when collecting SC from the placenta at birth, which can be considered a form of he alth insurance and protection for the newborn in the future. They can be used by this individual when a serious illness occurs. In Japan, for example, there is an entire government program that ensures that 100% of the population has IPS cell banks.
Examples of the use of SC in medicine
Steps of embryonic transplantation:
- 1970 - The first autologous SC transplants are carried out. There is evidence that in the former CCCP "youth vaccinations" were given to aging members of the CPSU Politburo several times a year.
- 1988 - SCs were transplanted into a boy with leukemia who still lives today.
- 1992 - Professor David Harris establishes SK bank, where his first child became the first client. His SC was frozen first.
- 1996-2004 – 392 transplantations of own SCs from the bone marrow were performed.
- 1997 - Donor SCs were transplanted from the placenta to a Russian cancer patient.
- 1998 - SCs were transplanted into a girl with neuroblastoma (brain tumor) - the result is positive. Scientists have also learned how to grow SC in vitro.
- 2000 - 1200 broadcasts.
- 2001 – the ability of adult human bone marrow SCs to transform into cardio- and myocytes was revealed.
- 2003 – data were obtained on the preservation of all SC bioproperties in liquid nitrogen for 15 years.
- 2004 – World Banks of SK collections already have 400,000 specimens.
ESC basic properties
Examples of embryonic stem cells can be any cells of the primary layers in the embryo: these are myocytes, blood cells, nerve cells, etc. Human ESCs were the first to be isolated 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 the discovery of the double helix of DNA and the decoding of 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 prohibited by official medicine for use as a treatment.
What is being used today
For treatment, only own SCs from the tissues of an adult organism are used, more oftenAll of these are red bone marrow cells. The list of diseases includes diseases of the blood (leukemia), the immune system, in the future - oncological pathologies, Parkinson's disease, type 1 diabetes, multiple sclerosis, myocardial infarction, strokes, diseases of the spinal cord, blindness.
The main problem has always been and remains the compatibility of SCs with body cells when they are introduced into it, i.e. histocompatibility. When using native SC, this issue is much easier to solve.
Therefore, to 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 tissues where SCs are stored and consumed as needed. The prospects for SCs are huge, because scientists hope to create from them the necessary tissues and organs instead of donor ones, according to indications.
Beginning history
In 1908 Alexander Maksimov (1874-1928), professor of histology at the Military Medical Academy of St. Petersburg, while studying blood cells, noticed that they are constantly and fairly quickly updated.
A. A. Maksimov guessed that it was not just a matter of cell division, otherwise the bone marrow would be larger than the person himself. Then he called this predecessor of all elements of the blood stem. The name explains the essence of the phenomenon: special cells are laid in the red bone marrow, the task of which is only in mitosis. At the same time, 2 new cells appear: one becomes blood, and the second goes into reserve - develops and divides again, again the cell goes into reserve, etc. with the same result.
These constantly dividing cells make up the trunk, from ittwigs move sideways - these are new emerging professional blood cells. This process is continuous and amounts to billions of cells every day. Among them are groups of all blood elements - leukocytes and erythrocytes, lymphocytes, etc.
Subsequently, Maximov spoke with his theory at a congress of hematologists in Berlin. This was the beginning of the history of the development of the SC. Cell biology became a separate science only at the end of the 20th century.
In the 1960s, SC began to be used in the treatment of leukemia. They have also been found in skin and adipose tissue.
Distinguishing Features of SK
Promising ideas do not exclude the existence of underwater reefs when put into practice. The big problem is that SC activity allows them to divide in unlimited quantities, and it becomes difficult to control them. In addition, ordinary cells are limited in dividing by the number of cycles (the Hayflick limit). This is due to the structure of chromosomes.
When the limit is reached, the cell no longer divides, which means it does not multiply. For cells, this limit differs depending on their type: for fibrous tissue it is 50 divisions, for blood SC - 100.
Secondly, SCs do not all mature at the same time, so any tissue has different SCs at different stages of maturation. The more normal the maturity of a cell, the less it has the properties of retraining into another cell. In other words, the genome laid down for all cells is similar, but the mode of operation is different. Partially mature SCs that, when stimulated, can mature anddifferentiate, these are blasts.
In the CNS these are neuroblasts, in the skeleton - osteoblasts, in the skin - dermatoblasts, etc. The stimulus for maturation is external or internal causes.
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 there is no Hayflick limit for them. ESCs divide endlessly, i.e. they are actually immortal (immortal). This is their second property. This property of ESC inspired scientists, it would seem, to be used in the body to prevent aging.
So why didn't the use of embryonic stem cells go down this path and be frozen? Not a single cell is guaranteed against genetic breakdowns and mutations, and when they appear, they will be passed down the line further and accumulate. We must not forget that human embryonic stem cells are always carriers of alien genetic information (foreign DNA), so they themselves can cause a mutagenic effect. That is why the use of their SC becomes the most optimal and safest. But another problem arises. There are very few SCs in an adult organism, and they are difficult to extract - 1 cell per 100 thousand. But despite these problems, they are extracted and autologous SCs are often used in the treatment of CVD, endocrinopathies,biliary pathologies, dermatosis, diseases of the musculoskeletal system, gastrointestinal tract, lungs.
More about ESC underwater 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 been solved today.
The use of embryonic stem cells in practice was at first ubiquitous, but the infinity of division of such cells makes them uncontrollable and makes them related to tumor cells (Konheim's theory). Here is another explanation for the ESC freeze.
Rejuvenation with ESC
A person loses his SC as he ages, their number is steadily falling, to put it simply. Even by the age of 20 there are few of them, after 40 years there is none at all. That is why, when in 1998 the Americans isolated ESCs for the first time and then cloned them, cell biology received a powerful impetus in its development.
There was hope for the cure of those diseases that had always been considered incurable. The second line is rejuvenation with embryonic stem cells by injection. But there was no breakthrough in this regard, because it is still not known exactly what SC do after being introduced into a new organism. Either they stimulate the old cell, or replace it completely - they take its place and actively work. Only when the exact mechanism of the behavior of the NC is established will it be possible to speak of a breakthrough. Today, great care is required in choosing such a treatment method.
ESC and rejuvenation in Russia
In Russia, restrictions on the use of ESCs have not yet been introduced. Here, embryonic stem cell therapy for rejuvenation is not carried out by serious research institutes, but only by ordinary beauty salons.
And one more thing: if in the West the testing of the action of ESCs is carried out in laboratories on experimental animals, then in Russia new technologies are tested on people by the same home-grown beauty salons. Booklets with all sorts of promises of eternal youth 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 one should not blindly trust technologies that have not been scientifically confirmed, many public figures outweigh the desire to look younger and more attractive, a person begins to run ahead of the locomotive. Moreover, before the eyes of those whom it helped. There are such lucky ones - Buynov, Leshchenko, Rotaru.
But there are many more unlucky ones: 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 the deterioration of their condition, they seemed to flourish and become younger, and then quickly died. Why this happens, no one can answer. Yes, atWhen ESC enters the aging body, they encourage cells to actively divide, the 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.
