Stem cells are now one of the most mysterious biological objects. Many myths and rumors surround these though small but important pieces of flesh. You can hardly tell true facts from false statements of numerous tricksters, who just dream of cashing in on them. In this article we will try to give possibly reliable information on this, no doubt perspective, source of health.

Let us start with a definition - stem cell (SC) is an immature cell, able to renew itself and develop into specialized cells of an organism. SC population has high proliferative potential and usually differentiates into several cell lines: any organ cells in an organism or any cell in an embryo. Growing organism, no matter human or animal, has billions of cells, all of which originate from one cell, zygote, resulting from gametic syngamy of male and female gametes. Zygote carries information about an organism, as well as the scheme of its sequential development. Copies of its DNA exist in every cell of a mature organism. During growth and development cell DNA changes - first, all zygote genes are "turned on", in other words, they can be expressed (as geneticists say), then some genes turn silent (their expression is cancelled), which makes cells more specialized. After the "switch" is turned off, muscle cells will produce nothing but muscle cells; skin cells will give birth to more skin cells, etc. Such way of cell development is essential for human (or animal) health - some specialized cells cannot be recovered or replaced after they have been damaged somehow. This phenomenon is the major cause for human sufferings.

In the process of embryogenesis (formation of a embryo) division of a fertilized egg produces cells, which have no other function but transfer of genetic material to next cell generations. Such cells are called embryonic stem cells (ESC) and their genome is still at the "zero point" - all mechanisms, defining their speciality, are silent. This possibly allows such cells to develop into any type of cells. In an adult or mature organism SC are found basically in the bone marrow and - very few - in all tissues and organs. Their central task is restoring damaged fragments of body parts with following mechanism: regulating system "informs" stem cells about damage, and blood flow carries them towards injured organs. Amazing ability of SC to turn to any needed cells (bone and smooth muscle cells and even neurons) in vivo provides recovery of almost any injury and stimulates organism's internal potential to regeneration.

In late 90s of the last century scientists designed a technique for isolating such cells and cultivating them as long as needed - eminent discovery, which offers breathtaking opportunities for the mankind, because now biologists are able to construct new cells (or even organs) in the laboratory. Scientists combine SC technologies with cloning and isolate adult DNA, which is then introduced to human egg and generates ESC with adult DNA, allowing further growing of organs in order to replace damaged ones without danger of rejection by a recipient organism. Another recent discovery shows the ability of some adult cells to generate ESC. If this fact is true, it eliminates one of the major obstacles on the path of using embryonic stem cells - biologists won't need to destroy human embryos for obtaining its SC.

What makes stem cells so unique? The answer may seem simple, but still we know little about molecular mechanisms, providing cells with such incredible potential. SC are pluripotent, in other words, they have equal chances to become any specialized cell, making these cells so compelling for therapists.

We would like to draw your attention to one important fact. Both stem cells and cell medicine are future prospects. Current list of diseases, which can be cured by means of stem cells without any dangerous side effects, is very short! Scientists keep performing a great number of experiments in the field of cell technologies. The results they obtain are striking and promising. Many patients now are longing for trying stem cells today - it's obvious.

But always bear in mind that:

1. Current clinical practice of SC' application is insufficient (Bone Marrow bank and hematology centres are the only exception);
2. Investigators have no idea about long-term effects of such treatment;
3. There always exists the risk of carcinogenesis;
4. SC therapy can cause infections: you should always know the history of the cell preparation and results of its infection safety tests;
5. Cell preparation can be immunogenic.