Gene Therapy.

Reading Gene testing for cancer, will give an idea of how important genes are in making you a potential candidate to getting cancer.  Your genes are present in every cell and control the functions and life of the cell.

When the gene undergoes a change, its commands the cell to also change. A cancer gene will tell the cell to grow and divide at an uncontrolled rate. This cell is now a cancer cell. The aim of Gene therapy is to alter or replace this faulty and changed gene.

Gene Therapy and Cancer.

Genetic therapy, still in clinical trial stage, is used to treat a variety of diseases like cancer, AIDS, heart diseases, diabetes, hemophilia and cystic fibrosis. To cure the cancer, it is necessary to alter the gene that has “gone bad”. Gene treatment does just that.

The genes tell the cell to make proteins. A mutated gene makes the protein to become faulty. Gene therapy introduces a normal gene into the body to correct this faulty protein.

How are the therapeutic genes introduced into the body?

Genetic engineering is the science which helps introduce the genes into the body so that they can function. For an introduced gene to function, it requires a carrier to enter the cell. A modified virus, such as a retrovirus, which has been rendered harmless, is used as a carrier to introduce the gene into the cell. Such a carrier virus is called a vector.

These viruses have an ability to recognize certain cells. Due to this ability, the carrier virus penetrates and infects the cell and introduces the new gene into the cell. Adenoviruses, Adeno associated viruses, herpes viruses, lentiviruses and poxviruses are also used as vectors.. Liposomes (fat particles) are also used as vectors. Choice of vectors depends on the requirements suggested by the genetic study.

The vector is introduced by directly injecting the vector carrying the gene into the tissue, you want io target, or by an intravenous route. Alternately, tissue from the body is removed and the vector is injected into the tissue in vitro ( in the lab). The cells are then injected into the tumor in the body. The new gene will start making a normal and functioning protein.

Image showing gene therapy.

(Click on image to enlarge).

Purpose of gene therapy.

1. To kill the tumor cells or to stop them from multiplying.
2. To make them more susceptible to the immune system.
3. To make them more vulnerable to chemotherapy or radiation or other cancer treatments.
4. Dendritic cells, which are immune cells are important to fight the cancer cells. These cells are removed from the body, made more cancer specific in the laboratory and introduced back into the body.

Risks of Gene Therapy.

As mentioned above, gene treatment of cancer is still in the clinical trial stage. It is not without risks, some of which can be serious.

1. Possible infection of healthy cells by the viruses which are used as vectors. This may lead to damage of the healthy cells, causing diseases and even cancer itself.
2. The genetic material may get wrongly introduced into the germ cells (sperms in men and eggs in women)of the reproductive system. The genetic changes caused will affect the future generations, if the patient has children after genetic therapy treatment .
3. The immune system of the body may see the introduced vectors as foreign body and this could generate an auto immune response  which could lead to inflammation or toxic reactions or may even cause organ failure.
4. The modified viruses, used as vectors, may regain their original virulence and may cause diseases.

To minimize risks, evaluation of gene therapy at multiple levels is done to ensure that safety is given top priority in carrying out clinical trails of gene therapy.

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