The recombinant DNA technology led to many innovations such as genetically engineered hormones, gene therapy and molecular diagnosis that played a crucial role in the field of medical science and healthcare. This led to the mass production of therapeutic drugs, treatment of diseases and early diagnosis.
In diabetic patients, the insulin which regulates the glucose and energy metabolism is either impaired or insufficient. So insulin needs to be given in regular doses. These problems were overcome with genetically engineered insulin. Insulin consists of two short polypeptide chains namely; chain A and chain B. These chains are linked together by disulphide bonds. In mammals, insulin is synthesised as a pro–hormone containing an extra C peptide. However, there was a big challenge in removing C peptide from the pro-hormone to make it mature insulin.
An American company Eli Lilly prepared two DNA sequences that corresponded to Chain A and B in the human insulin. Thereafter they inserted these DNA sequences in E. coli plasmids and insulin chains were formed. Both Chains A and B were extracted separately and interlinked with disulphide bonds. This gave rise to the human insulin which is used worldwide.
Another innovative application of recombinant DNA technology is gene therapy, which is employed to correct defective genes and cure diseases such as haemophilia and cystic fibrosis. Gene therapy was used for the first time in a person bearing non-functional T-lymphocytes, called Adenosine Deaminase Deficiency. In ADA deficiency, lymphocytes collected from the patient’s blood are grown in a culture. After this, a functional ADA is introduced into the lymphocytes with the help of an altered retrovirus vector. Thereafter, the genetically altered lymphocytes are returned to the patient’s blood by transfusion. As these cells are mortal, patients need regular infusions of genetically engineered lymphocytes.
In molecular diagnosis of the disease, Polymerase Chain Reaction or PCR and Enzyme Linked Immuno-Sorbent Assay or ELISA facilitates early diagnosis, even at low concentration. PCR detect pathogens in the body by amplifying their nucleic acid in suspected AIDS patients and cancer patients. Enzyme Linked Immuno-Sorbent Assay or ELISA detects diseases based on the principle of antibody-antigen interaction. It can detect the pathogenic infections by detecting the antigens in the body or detecting the antibodies synthesised against the pathogen.