Plants are the potential source for the commercial production of biopharmaceuticals such as proteins, peptides, enzymes and carbohydrates. Biopharmaceuticals have traditionally been produced by routine conventional systems such as microbial fermentation and cultured mammalian cells.
The demand for the pharmaceuticals and new therapeutic proteins, discovered through genomics, will increase considerably. The use of pharmaceutical proteins from natural source (animals and microbes) can pose risks. For example, many people have contracted diseases from contaminated blood products or hormones.
Besides, cost effective production from cell culture system hinder their commercial production. Although mammalian cell culture systems are advantages over microbial system due to post translational modifications but maintenance and other risk factors causing some setback.
Besides, mammalian cells are very sensitive to shear forces. More importantly, purification of recombinant proteins from cell culture system is also an expensive process. While searching for alternative source, plants are being considered as safe and favourable candidate due to their easy culture, harvesting and storage.
Processing of transgenic crops requires simple infrastructure and little capital investment. Moreover, due to the burst of research in plant genetic engineering production strategies becomes easier in the field of biopharmaceutical production. Considering the merits of plant source, it can be made to produce and store proteins in seed endosperm and oil bodies.
In the molecular farming of plants, it has been estimated that the cost of production of biopharmaceutical proteins could be 10 to 50 fold lower than producing the same proteins by microbial system. Many biotechnology companies are actively involved in developing field testing of biopharmaceuticals and also potential on plant expression system.
The first pharmaceutically relevant proteins made in plants were human growth hormone, which was expressed in transgenic tobacco in 1986. Since then many human proteins have been shown to be produced in plants. One of the pharmaceutical protein hirudin, known for their therapeutic use is now produced commercially in Canada for the first time.
Another classic example of molecular farming of one of the most expensive drugs on this world, glucocerebrosidase have been produced in transgenic plants and this technology made them much cheaper drug for the benefit of mankind.
In 1989, the first antibody was expressed in tobacco, which showed that plants could assemble complex glycoprotein with several subunits. The structural authenticity of plant derived recombinent proteins was confirmed in 1992.