Stem cells are precursors of specialized cells, such as blood, skin, liver, mucosa and other cells constituting tissues of the body. Since specialized cells can live for only a certain period of time, their number in the body should be constantly maintained. Serving as a sort of repair system in the body, stem cells can asymmetrically divide producing a mother cell, which ensures self-replication, and a new cell able to differentiate into a specialized cell.
Stem cells vary by their differentiation potency, which is the highest for the fertilized egg, zygote, able to differentiate into any cell type of the body and extraembryonic tissues. During its first divisions this potency persists. With the further development, stem cells become more specialized, and their differentiation potency decreases.
In our clinic, we use 5–8 weeks old fetal stem cells for treatment. The differentiation potency of these stem cells is very high and is preserved till the 9th week of gestation. These stem cells can differentiate into the widest range of cell types within the certain germ layer – ectodermal, endodermal and mesodermal. Moreover, the stem cells we use have the highest proliferative potential compared to other types of stem cells (adult stem cells, cord blood stem cells, etc.)
At the same time, the stem cells we use have already undergone specialization in the germ layers, lost their capacity of uncontrolled growth and "know for sure" what cell or tissue type they should differentiate into. Unlike treatment with embryonic stem cells (in vitro) of the early gestation term (1–2 weeks) capable of uncontrolled growth, which can cause teratomas, our stem cell therapy is not bearing the risk of tumorgenesis (tumor formation).
Moreover, transplantation of fetal stem cells does not lead to rejection by the recipient as the HLA expression in these cells is either absent or minimal. At the same time, adult stem cells and cord blood stem cells express histocompatibility antigens that requires HLA-based donor-recipient compatibility or immunosuppression (or use of these cells for autotherapy).
After the 9th week of gestation, stem cells undergo further specialization resulting in development of more specialized stem cells, which can be found not only in the fetus but also in a newborn and an adult organism. For instance, hemopoietic stem cells found mainly in the bone marrow are responsible for the constant formation of the new blood cells to substitute the destroyed ones. They give rise to two lines of more specialized stem cells that in the process of further specialization keep differentiating until they form erythrocytes, monocytes, B- and T-lymphocytes.
As we age, stem cell count in the body decreases. For a newborn, stem cell ratio stands at 1/10,000, for teenagers at 1/100,000, by the age of 50 it amounts to 1/500,000, and by the age of 70 only to 1/1,000,000. Therefore, the issue of cell pool replenishment and activation of one’s own stem cells is the key one for finding solutions on how to live longer, stay young and treat a wide range of diseases resulting in cell count reduction.
Administered into the recipient’s body, fetal stem cells migrate to the site of damage, engraft, proliferate, undergo specialization under regulation of a new host, and substitute lost or damaged cells, thus restoring the impaired body functions. Moreover, fetal stem cells can produce considerable amount of biologically active substances, e.g. hematopoietic growth factors, interleukins, nerve growth factors, tumor necrosis factors, angiogenic and neurotrophic factors, etc.