Medical dictionary

Stem cells

Stem cells called special cells of living organisms, which are characterized by the ability to change (differentiate) in a special way, that is, to gain specialization, and develop further as an ordinary cell. Stem cells can divide asymmetrically, as a result of which division creates a cell similar to the mother, that is, the process of self-reproduction occurs, and a new cell is able to differentiate.

The term "stem cell" was first used by a histologist from Russia Alexander Maximov. Stem cell research has been going on for over a century. In the sixties of the last century, it was shown that the intravenous administration of such cells from a healthy experimental mouse to an irradiated mouse leads to the production in the spleen of cell colonies of all hematopoietic differentiation directions. After the development of a clonal method for identifying precursor cells called colony-shaped units, it finally became possible to trace the differentiation of myeloid germs. There was also experience in transplanting stem cell colonies under a kidney capsule, resulting in the formation of adipose and bone tissue. In 1999, the journal Science discovered the discovery of embryonic stem cell cells as the third significant event in biology after the program "Human genome"and decryption double DNA helix.

Stem cells, like all other cells, multiply by division. Their main difference is that they can divide an unlimited number of times, and mature cells, in this case, have a limited number of cycles. The second characteristic feature of these cells is that, as a result of their division, one of the daughter cells remains stem, and the second differentiates. It is through such a system that stem cells can form a self-sustaining population.

When mature, stem cells go through several stages. Therefore, the body simultaneously contains stem cells of different degrees of maturity.

In various tissues and organs of an adult, there are partially matured stem cells, they are ready to quickly mature in order to turn into cells of the desired type. They are called blast cells. For example, partially matured brain cells are neuroblastsskeletal muscle is myosatellite cellsbones are osteoblasts etc. external and internal causes can trigger differentiation. Almost any cell reacts to any external stimuli, for example, to a substance that serves as a signal of overpopulation, and when there are many cells, such a signal can inhibit division.

Recently, interest in stem cells has not diminished, and many doctors and medical clinics call them the "panacea" for many diseases, even those that are considered incurable using standard therapeutic techniques. A lot of modern research suggests that stem cells are still able to withstand diseases and pathologies, for example, liver cirrhosis, such data were provided by scientists and the Institute of Clinical Immunology of Novosibirsk, and English scientists promised that in the near future it will be possible to grow stem cells missing teeth. There are a lot of such studies around the world. But is this really possible?

Stem cells are the foundation that gives rise to the development of the whole organism. In the early stages of development, the embryo consists entirely of stem cells, which subsequently begin to differentiate, from which tissues and organs are formed. In an adult, stem cells are only found in small amounts in bone marrow blood, and in very scanty amounts - in other tissues and organs. Due to their ability to transform into other cells, they play the role of emergency care: stem cells can be sent to the place of a malfunction in the body, being transformed into cells of damaged tissue or organ, which contributes to its restoration.

The issue of using stem cells in medicine is still highly controversial. While some praise them as the latest unique technique, other experts claim that stem cells are a mythology that has nothing to do with real medicine.

Watch the video: Stem Cells (January 2020).

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