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About Stem Cells.
What are stem cells?
Stem cells are special kind of cells which are unspecialized / undifferentiated, having capacity to self-renew and potency to give rise to different specialized cell types. Stem cells can be found in the living body (adult stem cells) or in the fetus.
What are the types of stem cells?
There are different types of stem cells depending upon the source they are derived.
- Embryos – Embryonic stem cells (ESCs)
- Fetal Tissue – Fetal stem cells
- Cord Blood - Cord blood stem cells
- Adult Tissue - Adult stem cells
- Hematopoietic stem cells
- Mesenchymal stem cells
- Neural stem cells
- Muscle derived stem cells
- Pancreatic stem cells
- Hepatic stem cells
Characteristics of stem cells
Stem cells have two important characteristics that distinguish them from other types of cells.
- Self-renewal - the ability to go through numerous cycles of cell division while maintaining the undifferentiated state
- Unlimited potency - under certain physiologic or experimental conditions, they can be induced to become cells with special functions such as the beating cells of the heart muscle or the insulin-producing cells of the pancreas.
What is Regenerative Medicine?
Research on stem cells is advancing knowledge about how an organism develops from a single cell and how healthy cells replace damaged cells in adult organisms. This promising area of science is also leading scientists to investigate the possibility of cell-based therapies to treat disease which as of now have no cure, is to as regenerative or reparative medicine.
Why focus on adult stem cells?
Adult stem cells typically generate the cell types of the tissue in which they reside. However, a number of experiments over the last several years have raised the possibility that stem cells from one tissue may be able to give rise to cell types of a completely different tissue, a phenomenon known as plasticity. Examples of such plasticity include blood cells becoming neurons, liver cells that can be made to produce insulin, hematopoietic stem cells that can develop into heart muscle and mesenchymal stem cells have the potency to develop bone, neurons, myocardium, endothelium, muscle tissues etc.
Adult stem cells are more safe and have no ethical issues when compared to embryonic stem cells and therefore, exploring the possibility of using adult stem cells for cell-based therapies has become a very active area of investigation by researchers.
What are the potential uses of human stem cells?
- Studies of human embryonic stem cells may yield information about the complex events that occur during human development.
- Medical researchers believe that stem cell therapy has the potential to radically change the treatment of human disease. A number of adult stem cell therapies already exist, particularly bone marrow transplants that are used to treat leukemia. In the future, medical researchers anticipate being able to use technologies derived from stem cell research for generation of cells and tissues that could be used for cell-based therapies. Today, donated organs and tissues are often used to replace ailing or destroyed tissue, but the need for transplantable tissues and organs far outweighs the available supply. Stem cells, directed to differentiate into specific cell types, offer the possibility of a renewable source of replacement cells and tissues to treat diseases including Parkinson's and Alzheimer's diseases, spinal cord injury, Cerebral stroke, burns, Multiple Sclerosis, Motor Neuron Disease, Duchenne's muscular dystrophy, ischemic heart disease, diabetes mellitus, Critical Limb Ischemia, vision and hearing loss, osteoarthritis, rheumatoid arthritis and many more.
- A primary goal of this work is to identify how undifferentiated stem cells become differentiated. Scientists know that turning genes on and off is central to this process. Some of the most serious medical conditions, such as cancer and birth defects, are due to abnormal cell division and differentiation. A better understanding of the genetic and molecular controls of these processes may yield information about how such diseases arise and suggest new strategies for therapy.
- Human stem cells could also be used to test new drugs. For example, new medications could be tested for safety on differentiated cells generated from human stem cell lines. Cancer cell lines, for example, are used to screen potential anti-tumor drugs. But, the availability of pluripotent stem cells would allow drug testing in a wider range of cell types.
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