About Stem Cell

The belief that there exists an undifferentiated cell which can be programmed into another type of cell forms the basis of stem cell biology. Today, stem cells treatments have become a reality. The capability of stem cells to regenerate organs and tissues opens a wide spectrum of treatment possibilities for many diseases that were considered incurable.

There is an increasing interest in using stem cells in treatment of degenerative diseases such as Parkinson’s disease, Alzheimer´s disease, diabetes, osteoarthritis (OA), knee injury, osteoporosis, myocardial infarction, and multiple sclerosis for which there is no curative therapy.

Stem cells, characteristics and properties

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Stem cells are distinguished from other cell types by two important characteristics. First, they are unspecialized cells capable of renewing themselves through cell division. Second, under certain physiologic conditions, stem cells can be induced to become tissue- or organ-specific cells with special functions. In some organs, such as the gut and bone marrow, stem cells regularly divide to repair and replace worn out or damaged tissues.

Nowadays, we know that stem cells are not only in the umbilical cord, but we can find them in all human body tissues. Stem cells are now isolated from adult specialized cells and there has been a continuing expansion in the number and type of stem cells under study.

Classification of stem cells

Stem cells can be classified into four broad types based on their origin. Stem cells from embryos; stem cells from the fetus; stem cells from the umbilical cord; and stem cells from the adult. Each of these can be grouped into subtypes. For example, adult stem cells are divided in germline and somatic (hemopoietic, mesenchymal, liver, epidermal, neuronal, eye, gut..)

Stem cells can also be classified according to its plasticity in totipotent, pluripotent, multipotent and unipotent cells. Totipotent stem cells have the potential to generate all the cells needed for human development, plus the extra embryonic, or placental, cells. Embryonic cells within the first couple of cell divisions after fertilization are the only cells that are totipotent. Pluripotent stem cells can give rise to all of the cell types that make up the body; embryonic stem cells are considered pluripotent. Multipotent stem cells can develop into more than one cell type, but are more limited than pluripotent cells; adult stem cells and cord blood stem cells are considered multipotent. They are found in specific organs and can only become cells within that organ; for example, multipotent stem cells in the brain can become nerve cells or other brain cells. These cells do have the potential to maintain and repair particular organs and tissues. Unipotent stem cells can be differentiated along only one lineage.

Finally, stem cells can be classified deepening on the source in autologous (cells from the same individual), allogenic (cells from the same species) and xenogeneic (cells from different species).

Neural stem cells show considerable promise for regenerative repair, pluripotent stem cells have an abundant potential in regenerative medicine, and mesenchymal stem cells are numerically the most favored cell type presently under clinical trial.