Understanding Stem Cells

What is a stem cell?

A stem cell is a basic cell which has the ability to differentiate into any other type of cell in the body.

These cells are unique because they are unspecialized; they renew themselves by dividing into several daughter cells identical to the mother cell till the need to differentiate arises; and have the ability to differentiate and become various other cell types when the need arises.

Types of stem cells

Two types of stem cells have been identified-Embryonic and Adult stem cells.

Embryonic stem cells

As the name suggests, they are taken from an embryo. An embryo is formed when an ovum or egg from a fertile female is fertilized by a male sperm. A three to five day old embryo is known as a Blastocyst. It has three layers

• 1. Trophoblast – the outside layer surrounding the embryo
• 2. blastocoel – hollow cavity inside
• 3. Inner cell mass – group of cells at one end of the Blastocyst. It is these cells that are taken as stem cells. These are unique cells as stated earlier. No other cell has the ability to renew and differentiate into many cells like heart, lungs, kidney, brain, blood, etc.

The embryos for study of stem cells are taken from embryos formed in vitro in laboratories and not from the body of a woman. During invitro fertility treatment, several eggs are taken from a female and fertilized out side the body under laboratory conditions. One or two embryos will be implanted later on. The rest of the embryos are frozen to be used later when needed. It is these embryos that are taken for stem cell studies with the consent of the Mother and Father.

Adult stem cells

Adult stem cells are found in each organ. For example in the liver or blood. But unlike embryonic stem cells they can only multiply to regenerate new cells in that particular organ only, to replace cells lost by disease, injury or by normal day to day wear and tear. They cannot differentiate into another cell type. The stem cells from the bone marrow have been used in the treatment of many blood related cancers. Research is still underway to study adult stem cells.

Differences between Adult and Embryonic stem cells

Embryonic stem cells are pluripotent, meaning they can differentiate into many cells. But Adult stem cells can only become cells similar to its origin. Plasticity or ability to differentiate may exist; research is going on.

Embryonic stem cells can be grown in cultures but adult stem cells are difficult to be grown in labs.

What is a stem cell line?

Stem cells belonging to one family, or group of cells formed from one Mother cell as it divides into daughter cells is known as a stem cell line. When doing research a stem cell line is usually used instead of stem cells from different origins.

Controversy about stem cells

Stem cells are taken from embryos. Even if formed under laboratory conditions, they are alive and can become a life. When embryos are kept frozen for fertility treatment at a later stage they may never be used, and may even be discarded. But when taken for study of stem cells an embryo is destructed, a life is lost. There are many ethical and religious issues arising because of this. Federal laws are also imposed to prevent unethical use of embryos.

Why the interest in stem cells?

There are many diseases without definitive treatment and cures. By studying how the cells divide and how mutations occur, resulting in various diseases, we may be able to find ways to treat theses illnesses.

New drugs are being experimented daily as treatment for a multitude of illnesses. Usually volunteer humans are subjected to these drugs before being approved for use. By using the drugs on the stem cells, a better understanding is possible regarding how they act and the side effects it causes.

Transplants using stem cells instead of donor organs are another area of research.

As you may now understand stem cells offer hope to many, but obtaining them is a problem with ethical issues cropping up. Let us hope that the current ongoing research will benefit mankind very soon.