Stem cells

Stem cells

Stem cells are defined as cells that do not have certain tissue characteristics, maintain their undifferentiated phenotype until the appropriate signal is received, and have the ability to self-renew and proliferate.

One of the greatest goals of mankind since its existence has been to find solutions to diseases and prolong life span. There is information that the mixture obtained from many different plants was used in treatment thousands of years ago. B.C. It is known that various diseases and treatments are described in a papyrus thought to belong to the year 1534. The desire of human beings to reach immortality in the subconscious has been the driving force of medical science until today.

Especially in the last 20-30 years, tissue engineering has progressed rapidly all over the world and at this point, it has come to the point that tissues and even 3D organs can be produced from human stem cells in the laboratory environment. Production of a cell, tissue or organ (autologous) by taking a person's own cell and applying it to himself; It can treat many diseases for which the pharmaceutical industry is insufficient and connects the patient to life.

Stem cells, which have the ability to self-renew and transform into different cells, are divided into 3 types according to their division and differentiation characteristics.

1. TOTYPOTENT STEM CELLS

As we know, life for mammals starts from a single cell called the zygote (fertilization of the egg by the sperm). This cell is a totipotent cell and carries all the functions necessary for the formation of an adult organism. A totipotent cell alone can create a living thing. It maintains this feature for 4 days after fertilization. Totipotent cells are not used in human therapy for ethical reasons.

1. PLURIPOTENT STEM CELLS

Embryonic stem cells are referred to as pluripotent cells obtained from the inner cell mass of the blastocyst. These cells have the ability to differentiate into three embryonic germ layers. The three germ layers make up more than 220 cell types in an adult. Some differentiated pluripotent cells can exist as multipotent cells (for example, in the bone marrow) in adults, but these cells have limited differentiation abilities. Embryonic stem cell research is one of the most important subjects of regenerative medicine because of their unlimited self-renewal and plasticity (transforming into different cell types) abilities.

1. MULTIPOTENT STEM CELLS (CELL USED IN STEM CELL THERAPY)

Adult stem cells are more capable of transforming into the organ or tissue from where they were obtained, and they are called multipotent stem cells. Multipotent stem cells; are undifferentiated cells found in differentiated tissues in adults that have the ability to regenerate dead or damaged cells. They are also called somatic stem cells. They are found in tissues such as bone marrow, muscle, eye, nerve, liver, and skin. They have the ability to divide and renew themselves. Stem cells are not found in the same number and potential in every organ and tissue in adults. For example, there are very few of these cells in the brain. For this reason, there is no organ regeneration such as a bone or tissue in brain damage, the damage is usually permanent and has serious consequences. Multipotent stem cells constitute the stem cell group used in the field of therapy.

1. Hematopoietic stem cells (HSC): Hematopoietic stem cells are the precursors of all blood cells. Hematopoietic stem cells are the precursors of all blood cells. Myeloid cells (monocytes, macrophages, basophils, eosinophils, erythrocytes, megakaryocytes/platelets and some dendritic cells), and lymphocytes (T-cells, B-cells, NK-cells) are terminal cells formed by differentiation of hematopoietic cells . Hematopoietic stem cells are found in the bone marrow of adults, thighs, hips, chest, ribs, and other bones. Cells can be taken directly from the hip bone with a syringe, or they can be obtained from the blood with the help of some drugs (cytokine). Stem cells, which are often referred to as bone marrow transplantation in leukemia patients today, are hematopoietic stem cells.
2. Mesenchymal Stem Cells (MSC): Mesenchymal stem cells are stem cells found in adipose tissue, bone marrow, and cord blood with a very high capacity for self-renewal, differentiation and especially tissue repair.
3. Adipose Tissue Stem Cells (SVF): Adipose tissue stem cells (ASC); It can be obtained by removing human adipose tissue with the lipoaspirate method and isolating it with manual special techniques in the laboratory environment. In many respects, they are similar to the mesenchymal stem cells (MSC) found in the bone marrow. Compared to bone marrow, removal of adipose tissue is less painful. In vitro, it has been shown that human adipose-derived stem cells (SVF) can differentiate into bone, cartilage, fat and muscle cells. It has been reported that fat-derived stem cells can be used in many different diseases and successful results can be obtained.

*Mesenchymal and fat-derived stem cells (SVF) are the most commonly used in the field of cellular therapies.