Biotechnological Application in Medicine

The rDNA technological processes have made an immense impact in the area of healthcare by enabling mass production of safe and more effective therapeutic drugs.  At present 30 recombinant therapeutics have been approved for human use the world over. In India, 12 of these are presently being marketed.

Genetically Engineered Insulin: Insulin consists of two short polypeptide chains; chain A and chain B, that are linked together by disulfide bridges.  In mammals, including humans, insulin is synthesized as a prohormone, which contains an extra stretch called the C peptide. This C peptide is not present in the mature insulin and is removed during maturation into insulin.

In 1983, Eli Lilly an American company prepared two DNA sequences corresponding to A and B, chains of human insulin and introduced hem in plasmids of E.coli to produce insulin chains.  Chains A and B were produced separately, extracted and combined by creating disulfide bonds to form human insulin.

Gene Therapy: Gene therapy is a collection of methods that allows correction of a gene defect that has been diagnosed in a child/embryo.  Correction of a genetic defect involves delivery of a normal gene into the individual or embryo to take over the function of and compensate for the non-functional gene.

The first clinical gene therapy was given in 1990 to a 4-year old girl with adenosine deaminase (ADA) deficiency.  This enzyme is crucial for the immune system to function.

As a first step towards gene therapy, lymphocytes from the blood of the patient are grown in a culture outside the body.  A functional ADA cDNA is then introduced into these lymphocytes, which are subsequently returned to the patient.  However, if the gene isolated from marrow cells producing ADA is introduced into cells at early embryonic stages, it could be a permanent cure.

Molecular Diagnosis:

Recombinant DNA technology, Polymerase Chain Reaction (PCR) and Enzyme-Linked Immuno-sorbent Assay (ELISA) are some of the techniques that serve the purpose of early diagnosis.

PCR:

A very low concentration of a bacteria or virus can be detected by amplification of their nucleic acid by PCR.  PCR is now routinely used to detect HIV in suspected AIDS patients. It is being used to detect mutations in genes in suspected cancer patients too.

ELISA:

It is based on the principle of antigen-antibody interaction.  Infection by the pathogen can be detected by the presence of antigens or by detecting the antibodies synthesized against the pathogen.

Transgenic Animals:

Animals that have their DNA manipulated to possess and express an extra (foreign) gene are known as Transgenic Animals.

Reasons for the production of transgenic animals:

a) Normal physiology and development:  Transgenic animals can be specifically designed to allow the study of how genes are regulated and how they affect the normal functions of the body and its development.

b) Study of disease:  Many transgenic animals are designed to increase our understanding of how genes contribute to the development of disease, so that investigation of new treatments for diseases is made possible.

c) Biological products:  Transgenic animals that produce useful biological products can be created by the introduction of the portion of DNA (gene) which codes for a particular product such as human protein (alpha – 1-antitrypsin) used to treat emphysema.  The first transgenic cow, Rosie, produced human protein-enriched milk (alpha-lactalbumin – 2.4 gm/ liter).

d) Vaccine safety:  Transgenic mice are being developed for use in testing the safety of vaccines before they are used on humans (polio vaccine).

e) Chemical safety testing:  Transgenic animals are made that carry genes which make them more sensitive to toxic substances than non-transgenic animals. They are then exposed to the toxic substances and the effects studied.

Ethical Issues:

The Indian Government has set up organizations such as GEAC (Genetic Engineering Approval Committee), which will make decisions regarding the validity of GM research and the safety of introducing GM-organisms for public services.

Biopatent:

A patent is a right granted by a government to an inventor to prevent others from making commercial use of this invention. Now, patents are granted for biological entities and for products derived from biological resources.

Biopiracy:

It is the term used to refer to the use of bio-resources by multinational companies and other organizations without proper authorization from the countries and people concerned without compensatory payment.

In 1997, an American company got patent rights on Basmati rice through the US Patent and Trademark Office.  This allowed the company to sell a ‘new variety of Basmati, in the US and abroad.  This ‘new’ variety of Basmati had actually been derived from Indian farmer’s varieties. Indian Basmati was crossed with semi-dwarf varieties and claimed as an invention or a novelty.

Several attempts have also been made to patent uses, products and processes based on Indian traditional herbal medicines, e.g., turmeric and neem.