Somatic stem cells are also referred to as adult stem cells. Unlike embryonic stem cells, somatic stem cells come from a fully developed human being. Somatic stem cells are somewhat specialized to produce certain kinds of cells. However, scientists are currently working on ways to increase their range of use in cutting-edge therapies.
Adult stem cells have been found in a wide range of organs and tissues, including bone marrow, blood vessel, brain, epithelium, heart, intestine, liver, ovary, skeletal muscle, skin, teeth, and testis.
While these cells are programmed to become a certain type of cell, they are still capable of differentiation. For example, bone marrow stem cells can differentiate into either red or white blood cells. While brain stem cells could form neurons or supporting brain cells, they would typically not become cell types found in other organs.
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Two Types of Differentiation
Somatic stem cells typically divide to form mature cell types that have the characteristics necessary to become a functional part of tissues or organs, a process called normal differentiation.
Certain types of somatic stem cells have been found to have the capacity to give rise to cell types for organs or tissues not in their lineage. For example, brain stem cells that differentiate into cardiac muscle cells. This phenomenon is called transdifferentiation.
Doctors performed the first bone marrow transplant in 1968. The procedure also marked the first medical use of somatic stem cells, as bone marrow cells can differentiate into red blood cells or white blood cells. Today bone marrow transplants are used to treat a range of ailments, from blood cancers to immune disorders.
In 2010, a biotech company called Neuralstem began conducting clinical trials for the use of spinal cord stem cells to treat Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig’s Disease. The second phase of these trials was conducted in September 2013.
Adult Stem Cells vs. Embryonic Stem Cells
With embryonic stem cells, which are stem cells derived from fertilized human eggs, sparking an intense political and ethical debate, many researchers are turning to somatic stem cells as a less divisive alternative.
The problems is that embryonic stem cells can become any type of cell in the body -- while somatic cells are more restricted to a specific lineage. Embryonic stem cells are also more easily grown in culture, according to the National Institutes of Health.
However, because a patient's own cells can be used in a somatic stem cell treatment regimen -- they are thought to be less likely to cause a rejection after transplantation. The lack of a rejection response by the body's immune system would eliminate the need for immunosuppressive drugs, which often cause undesirable side effects.