has been nearly half a century, from the time when the leading schools of national hematology first published data on the "eternal" cells that give life to all the body and supporting it from start to finish.But the level of scientific knowledge and technical equipment of the laboratories of the time did not allow to take the next step in the study of these mysterious cells.Their time came only in the early 90s, when US scientists re "discovered" the stem cells in the bone marrow first, and then in all the organs and tissues of the higher animals.When the public learned that stem cells can be introduced into the body artificially, the scientific world hummed like disturbed beehive, and businessmen from medicine immediately started development of this same oblasti.Chto are stem cells?This can be explained as follows: stem cells are called universal cell organism that can, under certain conditions develop into any kind of tissue and contribute to the formation of any organ - the liver, kidneys, heart, bra
Where did they come from?We know that everyone is descended from a compound of the egg and sperm.That is the origin of all that we have, we owe to two cells are combined into one - a zygote.That it divides and gives rise to cells that do not have other functions in addition to the transfer of genetic material to the next cell generation.This embryonic stem cells.Of these, all other developing highly differentiated body cells.After the "segregation of duties", these cells are closed to further changes and can only be accessed by "reading", each in a specific format: a nerve cell - it's just a nerve cell, unable to participate in the creation of the epithelial tissue or part of the myocardium, etc..At the same time, some stem cells still manage to slip away from certainty and remain available for further changes only in case of emergency.
Thus, stem cells - is a versatile building material, from which grow anything.While the human body is good, the stem cells freely and independently "wander" in its open spaces.But as soon as the stem cells are derived genetic signal (malfunction, damage to tissue or organ), they bloodstream rush to the affected organ, find any damage and turn on the spot in the appropriate cells of the body - bone, smooth muscle, liver, nerve, etc.
The human body contains approximately 50 billion of stem cells, which are regularly updated.Over the years, the number of living "bricks" is reduced - for them is more work, and replace them with nothing.This process starts as early as 20 years, and in 70 years they left quite a bit.Moreover, stem cells are a middle-aged man is not as universal: the blood cells they can become still, and nerve - no longer exists.But if it is possible to artificially introduce stem cells into the body, i.e.replace dilapidated or diseased cells, then it is really back to health, and even significantly extend human life.
Where do we get these same stem cells for the artificial introduction?Today it is considered that scientists can obtain stem cells, cultivate and guide them on the correct path - for this there are several ways:
- first - person can be a donor of stem cells for yourself.Their greatest amount is in the pelvis bone marrow.They are extracted by means of a puncture, and then activate them in a special way, building up and injected back into the laboratory into the body, where, with the participation of special signaling substances they are sent to the "sore spot".
- The second source of stem cells is umbilical cord blood is collected after the baby is born.Taking it from the cord and putting in a special storage, the stem cells can then be used to recover almost any tissue and organ of the man, as well as to use them to treat other patients provided for compatibility antigens.
- The source of the following type of stem cells (fetal) is abortive material is 9-12 weeks of pregnancy.This source is by far the most frequently used.But in addition to ethical and legal tensions, these cells can sometimes cause graft rejection.In addition, the use of unverified abortive material is fraught with infected patients with viral hepatitis, AIDS, etc.If the material to diagnose the virus, increasing the cost of the method, which ultimately leads to an increase in the cost of the treatment.
- Finally, another source of "miracle-builders" is a blastocyst, which is formed to 5-6 insemination day.This embryonic stem cells.They are most versatile when compared with adult stem cells and can differentiate into all types absolutely cells.The positive side of using these versatile stem cells should be considered the fact that the cells as if no one owns, and does not perform any special function, and therefore does not arise for the transplant rejection reaction.
This finding provides a tremendous opportunity for the medicine, but it's still a matter of the future, because in spite of the long-term work of scientists around the world in this direction, achievement is still modest.True stem cells, apparently, is distinguished from the others, that does not carry any specific markings remain faceless as long as it does not decide the fate of.But to determine the fate of this artificially, using one or another, sometimes very complex and labor-intensive methods, one can very rarely.
There is another point that deserves attention.A stem cell with characteristics very similar to a tumor cell.The only difference is that the tumor cell is not willing to ripen under any circumstances, share and continuing to build up a lot of their own kind.But where is the line that divides these two types of cells?In a healthy organism is actively functioning security system.Its activity leads to loss of daughter cells ability to reproduce the infinite and to minimize the risk of a malignant or benign tumor.There is a real danger of the introduction of poorly differentiated cells outside their uncontrolled reproduction in the patient's body and consequently tumor growth.The literature describes many instances of just such a development.
The other most common problem in tissue transplantation in general and stem cells of different degrees of maturity in particular, are already mentioned complications of immune nature, including those related to the development of the reaction "graft versus host".Rejection and destruction of the transplanted cells are, perhaps, to the most favorable outcome in this case.
remains an open question as to regulate the future behavior of transplanted cells in the body.In most cases, scientists can not reliably determine the course of the experiment, some of the introduced cells take root, and what is not, than due to the effects obtained and how to avoid unwanted directions.Moreover, there are currently no technologies to be absolutely sure that the transplanted cells come only in the body in need of intervention.In other words, one hundred percent no guarantee that in the muscle can not grow the bone, while the aim of the intervention was to eliminate cosmetic skin defect.Even when using their own cells derived from, we can not bone marrow of the patient and processed in the laboratory to reliably determine what happens to the cells extracted from the usual for their microenvironment and placed in artificial culture media for the "enrichment and activation."How do they enrich?What are activated?And the possibility of contamination of the culture of stem cells, preparing for replantation, viruses or other micro-organisms can not be excluded even with all the precautions in a scientific laboratory, not to mention the beauty salons and dental offices.