Gene therapy in India

Introduction

At present, about 72 to 96 million people in India are expected to be affected by some form of rare disease.

Rare diseases are the conditions which are:

1. Life-threatening or chronically debilitating

2. Statistically rare (less than 1 in 2,000 people living with condition)

3. Complex, which means special combined efforts are needed to address them.

Approximately there are 5,000 to 8,000 different rare diseases and most have a genetic origin. While there are many different rare diseases, they have many things which is common to them including that they often:

1. Have no cure

2. Cannot be prevented

3. Have no effective treatment.

Rare diseases have many forms and include some cancers, auto-immune diseases, metabolic conditions and inherited malformations. Some examples of the rare diseases are:

thalassemia

sickle-cell anaemia

cystic fibrosis

muscular dystrophy

spina bifida

haemophilia.

Thus, we need gene therapy in order to treat different rare diseases.

Gene therapy holds promise for the treatment of a wide range of diseases, such as cancer, cystic fibrosis, heart disease, diabetes, haemophilia and AIDS.

You will be benefited from reading this content by knowing about gene therapy.

In India though the interest in gene therapy took some time but with the ﬁnancial assistance provided by different government agencies, the country has shown rapid improvement in gene therapy-related research placing India third among major Asian countries having gene therapy laboratories.

The main aim here is to develop the new institutions for gene therapy research, strengthening of existing institutions which have good expertise in this area in order to initiate work in molecular genetics for decreasing burden of genetic disorders in the country.

The pioneer of the gene therapy-related research in India is Advanced Centre for Treatment, Research and Education for Cancer (ACTREC) where active work on the gene therapy for head and neck cancer using the synthetic vectors is being carried out.

It is heartening to note that the scientists in over dozen of labs in India are working hard with the small steps in contributing towards gene therapy work.

What is gene therapy?

Genes contain DNA — the code that controls much of your body's form and function, from making you grow taller to regulating your body systems. Genes which don't work properly can cause disease.

Gene therapy refers to technique of using the normal functioning gene to treat a genetic disease either by repairing or replacing or regulating the defective gene.

Gene therapy involves altering of the genes inside your body's cells in an effort to treat or stop the genetic disease.

Types of gene therapy

Gene therapy is classified into the somatic cell gene therapy and the germline gene therapy, depending upon the type of cells that are modiﬁed by the therapeutic genes.

1. In somatic cell gene therapy, genetic changes are directed towards somatic cells. As these cells are non-reproductive, effect is not passed into future generations, making it safer. The disadvantage is the short duration of effects of the somatic cell therapy as most tissues are replaced by new tissues.

2. In the germline gene therapy, germ cells, i.e. either the sperm or the ova are introduced with the therapeutic gene, leading to changes that are inheritable, i.e. changes in gene may affect the future generations.

Gene therapy is also classified based upon the technique of delivery of vectors to the target cell. These are:

1. Ex-vivo Gene Therapy: It is where the defected cells are extracted out of the body and targeted with therapeutic gene. Once successfully modiﬁed, they are cultured ex-vivo and transferred back to the host, where now the corrected gene replicates.

2. In-vivo Gene Therapy: In this modality, a vector that is capable of carrying the therapeutic gene, is used to inject host cells with normal gene.

The type of change brought out in the faulty gene classiﬁes the gene therapy as either gene replacement or gene addition.

1. Gene Replacement: Gene replacement means replacement of defective gene with a corrected one.

2. Gene Addition Therapy: Gene addition means restoration of normal function of cell by addition of normal or functional copy of gene into genome. This concept is used primarily in the various gene therapy related research on cancer.

Why is gene therapy practised?

Gene therapy is used to correct the defective genes in order to cure a disease or help your body to better fight disease.

Researchers are investigating the several ways to do this, including:

1. Replacing mutated genes. Some cells become diseased because certain genes incorrectly work or no longer work at all. Replacing the defective genes may help to treat certain diseases. For instance, a gene called p53 normally prevents the tumor growth. Several types of cancer have been linked to the problems with the p53 gene. If doctors can replace the defective p53 gene, that may trigger the cancer cells to die.

2. Fixing mutated genes. Mutated genes which cause disease could be turned off so that they no longer promote disease, or the healthy genes that help prevent disease could be turned on so that they can inhibit the disease.

3. Making the diseased cells more evident to the immune system. In some cases, your immune system doesn't attack the diseased cells because it doesn't recognize them as the intruders. Doctors can use gene therapy to train your immune system to recognize the cells that are the threat.

Risks associated with gene therapy

Gene therapy has some potential risks. A gene can't be easily inserted directly into your cells. Rather, it usually has to be delivered using the carrier, called a vector.

The most common gene therapy vectors are the viruses because they can recognize certain cells and carry genetic material into the cells' genes. Researchers remove original disease-causing genes from viruses, replacing them with the genes needed to stop the disease.

This technique has the following risks:

1. Unwanted immune system reaction. Your body's immune system may see the newly introduced viruses as the intruders and attack them. This may cause inflammation and, in the severe cases, organ failure.

2. Targeting the wrong cells. Because viruses can affect more than one type of cells, it's possible that the altered viruses may infect the additional cells — not just the targeted cells containing the mutated genes. If this happens, healthy cells may be damaged, which can cause other illness or diseases, such as cancer.

3. Infection caused by the virus. It's possible that once introduced into your body, the viruses may recover their original ability to cause disease.

4. Possibility of causing a tumor. If the new genes get inserted in wrong spot in your DNA, there is a chance that the insertion may lead to tumor formation.

How is gene therapy done?

Gene therapy works by replacing or inactivating the disease-causing genes. In some cases, gene therapy introduces the new genes into the body to treat a specific disease.

1. With gene therapy, doctors deliver a healthy copy of a gene to the cells inside the body. This healthy gene may replace a damaged (mutated) gene, inactivate the mutated gene or introduce an entirely new gene.

2. Carriers, called vectors, transport these healthy genes into the cells. In most cases, the vectors are the modified viruses that do not cause disease. The vectors may also be certain types of bacteria or circular DNA molecules (plasmid DNA). Additional methods to package and deliver the genetic material are also being actively investigated, such as the use of nanoparticles, encapsulating lipid molecules and the use of electric currents.

3. Injection or intravenous (IV) infusion introduces the vectors into the body. In some cases:

A. Doctors collect the cells from a patient.

B. Add the vectors in a laboratory.

C. Return the vector-containing cells to the patient’s body through the injection or IV infusion.

Conclusion

Through this content we come to know about gene therapy that gene therapy is used to cure rare diseases which mostly have a genetic origin. It is an experimental treatment which uses genetic material to treat or prevent rare diseases. The possibilities of the gene therapy hold much promise. Clinical trials of gene therapy in people have shown some success in treating the certain diseases, such as:

1. Severe combined immune deficiency

2. Haemophilia

3. Blindness caused by retinitis pigmentosa

4. Leukaemia

But several significant barriers stand in the way of gene therapy becoming a reliable form for treatment, including:

1. Finding a reliable way to get the genetic material into the cells

2. Targeting correct cells

3. Reducing risk of side effects

Gene therapy continues to be a very important and active area of the research aimed at developing new, effective treatments for a variety of diseases.

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