Stem cells are called progenitor cells, from which can be formed by all other types of cells, which already make up the human body. The term "stem cell" was first introduced in 1908 by Russian hematologist from St. Petersburg Maksimov. Significant amount of stem cell research conducted hematologists A. Friedenstein and ai Chertkov in Russia since the late 60's. The discovery of stem cells is in line with such great achievements of mankind as the discovery of double-stranded dna chain, or anti-bacterial properties of penicillin. The journal Science named the 1999 "Year of stem cells." Perfect stem cells are cells of blastocyst.

These are cells of the human embryo, from which later formed the entire body. Such cells according to the classification assigned to the most versatile and called totipotent. As the embryo cells gradually differentiated, that is, there is a gradual specialization of these cells. Such cells are called pluripotent. The resulting abortion abortive material is the source of so-called embryonic or fetal stem cells.

These cells are found active application in cellular technology treatment of various diseases. In established human body has about 1012 hundred different types of cells. They require constant replacement as they are aging and dying off. This function is performed by the replacement stem cells that circulate in the bloodstream. Such cells are called multipotent because they have more specialization. In multipotent cells enter the bloodstream from the bone marrow, which serves as a depot for stem cells. Throughout the life of a person in the bone marrow are pluripotent stem cells.