Sunday, August 30, 2009

rDNA tech products


The above picture is interesting. The fish are called glofish. They are genetically altered fish using rDNA technologies, so they can glow! These genetically modified fish are approved by US FDA. Recombinant animals, pharmaceutical products, and foods are closer to you than you think! I got the above image from here.

Technology platforms are the springboards for creating new products that provide marketing successes. For eg., capsule technology has created many pharmaceutical formulations of various drugs, and big businesses are built on the capsule technology platform. Today, the most robust futuristic technology platform for mega business prospects is rDNA technology. The market is still not crowded, there are hefty margins. There is no commoditization in this field like chemical or natural ingredient based pharmaceuticals or healthcare products. rDNA tech is still mysterious to many.

rDNA stands for recombinant DNA (deoxyribose nucleic acid)

DNA is the name of a molecule that occurs in the nuclei of cells. It also occurs in viruses (that do not have nuclei). DNA is the fundamental molecule of life. It has information in the form of codes for all the characteristics or traits of an organism. For eg., actress Aishwarya Rai has a DNA code in her cell for her beautiful eyes.

DNA molecules combine with certain proteins to become chromosomes. The chromosomes are stained easily by certain dyes and stand out when seen through microscope. The 46 chromosomes (ie., 23 pairs) in the human cell refers to the 3 billion base pairs of DNA. Chromosomes are made up of DNA. The no. of chromosomes are fixed for a species. For eg., human cells have 23 pairs or 46 chromosomes. Potato cells have 48 chromosomes. Rabbit has 44 chromosomes.

Similarly, genes are parts of the DNA molecule. A gene is a sequence of the DNA molecule. Normally, a single gene codes for a specific trait.

So, to summarize:

DNA - the basic information molecule with a double helical structure in humans, makes up the chromosomes. Genes are parts of the DNA molecule.

So each portion of a DNA molecule codes for something - a trait or a process in the cell. If you identify and isolate a portion of the DNA molecule responsible for say producing insulin and introduce it in to the genetic structure of a compatible bacterium or yeast cell, then it is possible that the host bacterium or yeast cell will start manufacturing insulin and express it in large quantities out of the cell in to the fluid outside. Or the insulin may remain in the cytoplasm of the host cell.

The insulin thus manufactured by the yeast or bacterium cell can then be extracted out, isolated, purified, suitably formulated, and administered to patients.


This is crudely the rDNA tech process...

rDNA concept

As the word implies, the word recombinant refers to an organism or cell in which genetic recombination (new genetic combination) has been done. New genetic combinations occur naturally during reproduction (recombination) in the offspring. The offspring has new genetic combinations that are not present in the parents. So genetic recombination does occur in nature through reproduction.

Today, scientists use rDNA technology to do what nature does - ie., create new genetic combinations in cells. rDNA technology creates new genetic combinations usually in yeasts like Sachharomyces cerevisiae or bacteria like Escherichia coli using certain genetic engineering techniques. Thus, an alteration in genetic structure of the yeast cell or bacterium is done using rDNA technology.

WHY IS THIS ALTERATION DONE USING rDNA TECHNOLOGY?


In the pharmaceutical field, this genetic modification is done, to use the 'new yeast cells' or the 'new bacterium' to manufacture large quantities of therapeutic chemicals - usually proteins - that have health and commercial value. These therapeutic proteins expressed by the genetically modified yeast cells or bacteria are extracted, formulated usually in ampoules for injections, and marketed to doctors for administration to suitable patients.

Role of enzymes in creating rDNA tech products

Enzymes (all enzymes are proteins) are important chemical reactants or accelerators of chemical reactions that are used in large quantities to manufacture the rDNA tech products. The types of enzymes used are mainly restriction enzymes (that scissor DNA strands at specific points), and ligases (that restitch the DNA). Thus, the rDNA tech is an interplay of DNA, and enzymes.

To put the rDNA concept in an over simplified form, the required DNA sequence (that codes for say manufacturing insulin, the peptide or proteinaceous hormone) is cut out and stitched in to the DNA of a compatible yeast cell or bacterium. This genetically modified yeast or bacterium cell then starts manufacturing the protein of pharmaceutical interest (for eg., insulin the peptide hormone).

For eg., recombinant insulin and recombinant erythropoietin are two popular rDNA tech products.

rDNA human insulin is manufactured usually using Escherichia coli (a gram negative bacterium) or sometimes yeast. The manufacturing is through a complex process utilizing DNA synthesizers, fermenter tanks, centrifuges etc.

rDNA erythropoietin is used to stimulate production of red blood cells in the management of anemia due to chronic kidney disease and cancer chemotherapy. In 2007 the market for this product (erythropoietin stimulating agents market) was 11.7 billion USD. Basically, it is reckoned that rDNA tech based pharma product market is multibillion.

There are many types of rDNA products - they are mainly proteins such as hormones, insulin and blood factors.

DNA synthesizers

DNA synthesizers have their origin in the human genome project. This was the international scientific project that mapped the entire human genetic information. The human genome project determined the complete structure of the human DNA molecule and the functions. rDNA technology has its roots in the methods used in the human genome project. DNA synthesizers too are based on the methods used by scientists of the human genome project.

DNA synthesizers are machines that use a strand of DNA as a blueprint and they manufacture required DNA strands in large quantities that are in turn used in rDNA tech product manufacture.

rDNA tech is applied in agriculture too

Bt cotton and Bt brinjal are important rDNA tech based agri products. Bt crops contain nonplant genes in plants. Bt stands for Bacillus thuringiensis. This bacterium produces crystal proteins that are lethal to insect larvae. Thus, Bt crystal protein genes (ie., bacterial genes) have been transferred to cotton, soya, brinjal, and corn using rDNA techniques so that these plants can produce the crystal proteins to protect themselves from pests like American boll worm and European corn borer. Hence, Bt cotton and Bt brinjal are described as pest resistant plants. These are exceptional plants that contain bacterial genes for pest resistance.

Hence, Bt brinjal is called a GM food (genetically modified food). Are they safe? Is it safe for my children to consume good quantities of GM Bt brinjal regularly? Well, the commercial marketers of Bt brinjal claim it to be safe!!

Mind you, rDNA tech based pharmaceutical products have to undergo a battery of preclinical and clinical trials, and continue to have a long term phase 4 postmarketing surveillance clinical study to monitor safety and efficacy. But GM foods have none of this!!

Whether one likes or dislikes, technological change is a part of modern society. rDNA tech products are making their sure entry in to pens of prescribers. They are high value products with high growth. They address the medical management needs of clinicians not addressed earlier. So it is important that the Indian pharma industry continues appreciating this rDNA tech platform to power ahead in the field of biosimilars and biotech products.

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