Pluripotent cells At the blastula stage cells of mammalian embryos lose their totipotency property, becoming a pluripotent (from Latin ldquo;pluralis

Stem cells (pluripotent and unipotent) and therapy

Pluripotent cells

At the blastula stage cells of mammalian embryos lose their totipotency property, becoming a pluripotent (from Latin “pluralis” — “multiple” and “potency”). These cells still retain the ability to go on a particular path of development, from them can form various cells, tissues and organs, but the new body cannot be formed from them. Interestingly, that a few pluripotent cells persist in the adult human body. They are called stem cells (because they are like the trunk, from which grow a variety of cells of the whole body). From them constantly form cells that are needed to restore the body. Stem cells, unlike the rest of human body cells can divide indefinitely (epithelial tissue cells cannot divide more than 50-55 times). At the same time, one of the daughter cells remains a stem, and the second differentiates, turning into a functioning cell, such as a red blood cell or lymphocyte. Due to this, in particular, there is a constant renewal of cell composition of blood. Not casually, the term “stem cell” in 1908 for the first time was applied to the blood-forming cells by Russian histologist Alexander Maksimov (1874-1928). However, as it is now revealed, their function in the body is much wider than the formation of blood cells. Stem cells may form any of about 350 types of human cells.

Stem cells in the tissues of the human embryo are about one for 10 thousand of normal cells, and in elderly persons aged 60-80 years old — one for nine million. That is why in the elderly regenerative processes occur so slow.

Unipotent cells

Most of dividing adult cells are unipotent (from Latin “unikus” — “single of its kind” and “potency”), because they can develop into cells of one type. This group includes, for example, cells that form sperm.

Stem cell therapy

Currently, the use of stem cells or their products in medicine, that is called a cell therapy, is considered to be a promising way to overcome the consequences of the many very serious diseases: malignant tumors, disorders of the immune system, metabolism pathology, and other pathologies. However, their role is not in the treatment per se, but in restoring functions of bone marrow, blood and immune system of the patient after treatment.

Optimistic researchers even believe that from stem cells over time, you can create tissues and even grow whole organs for transplants to be used instead of donor organs. Grown from the patient's own cells, grafts won’t be rejected by the immune system. Taken from http://worldofschool.org

However, the massive use of stem cells causes some concerns. The fact that in the cell therapy into human body are injected thousands of cells capable of infinite number of divisions, and this property is inherent in cancer cells. Therefore, there is a fear that the “treatment” by stem cell not only rejuvenates organism and stimulates the immune system, but can also lead to cancer. Moreover, obtaining stem cells is associated with usage of human organs. All this together imposes a serious moral, and in many countries, legal restrictions on the manipulation of stem cells.

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Questions:
  • What are the properties of stem cells?

  • Why somatic mammalian cells in contrast to the hydra cell lose totipotency?