Stem Cells

The subject of stem cells has been attracting so much attention in the lay press these days that a lack of knowledge about it may be fatal to one's self-respect! This small write-up is an attempt to enlighten the lay reader about the basics of stem cells.

To understand stem cells we will have to go back to our origins. All of us begin our life as a single cell in our mothers' wombs. This single cell multiplies many times by repeated cell division to form the different organs and tissues of the body. It is easy to understand that these primitive embryonal cells have three special characters that are not found in adult cells namely

a. They are undifferentiated cells
b. They are capable of propagating themselves for prolonged periods of time by repeated cell division
c. They can differentiate themselves into specialized cells, like the brain cells or the heart muscle cells. Cells that are able to differentiate into other specialized cells are called pluripotent cells.

Stem cells are cells that have retained the above three characters.

There are two basic types of stem cells

a. Embryonic Stem Cells
b. Adult Stem Cells

Embryonic Stem Cells
As the name suggests these are stem cells derived from embryos. However they are not obtained from naturally fertilized eggs but are derived from eggs that have been fertilized in vitro (test tube babies). After isolation from the embryo they are placed in a culture medium where they multiply and thus millions of embryonic stem cells are obtained.

Adult Stem Cells
These are undifferentiated cells found among differentiated cells in certain tissues and organs of an adult. The function of these cells is to repair the cells of the organs in which they are found. The origin of these cells is still not clear but they are found in many organs like the bone marrow, brain, peripheral blood, blood vessels, liver, skin and muscle.

Differences between Embryonic and Adult Stem Cells.
Embryonic Stem Cells are relatively easy to grow in cell culture whereas Adult Stem Cells are difficult to grow. The former are able to differentiate into any cell of the body whereas the Adult Stem Cells can differentiate only into cells of the tissue in which they are found. But the great advantage of Adult Stem Cells is that they can be obtained from the patient's own body, cultured and reintroduced into the patient. This eliminates the risk of rejection that could occur if Embryonic Stem Cells from donors are used.

Potential Uses of Stem Cells
a. Research into Embryonic Stem Cells would yield information about the complex mechanisms involved in the differentiation of undifferentiated cells. This would lead to a better understanding of diseases like cancer.
b. Testing of New Drugs: The Stem cells could be made to differentiate into differentiated cells and these could be used to test the safety and efficacy of new drugs.
c. Cell based Therapy: Perhaps the most exciting use of stem cells, the stem cells could be used to replace damaged cells of various organs like the brain, heart, pancreas and could therefore be used in the treatment of diseases like Parkinson's Disease. Alzheimer's Disease, Diabetes and to regenerate the dead heart muscle cells following heart attacks. It may also be used to treat Congenital and Birth Defects.