Molecular Farming

The issue of genetically modified crops has been around for a number of years and continues to be a controversial subject. “Molecular farming” is an application of this technology; it involves the use of plants, and potentially also animals, as the means to produce compounds of therapeutic value.
Terminology
A number of different terms occur in reference to the use of genetically altered organisms for the production of therapeutics. Pharming is frequently used; in some instances it refers to the use of plants for the production of pharmaceuticals, but often it describes the use of animals, not plants, for the production of drugs. The Canadian Food Inspection Agency uses the term Plant-made Pharmaceutical (PMP) throughout its documentation. In some instances organizations will specify Plant Molecular Farming, to avoid confusion with the animal-sourced technique. Biomanufacturing (use of biological organisms to manufacture products of interest) and biopharmaceuticals (pharmaceuticals from biological organisms) are also terms that appear frequently in the literature. The terms plant-derived product of interest (PPI) and plants with novel traits (PNT) are also found in some cases.

Advantages
Plants do not carry pathogens that might be dangerous to human health. Additionally, on the level of pharmacologically active proteins, there are no proteins in plants that are similar to human proteins. On the other hand, plants are still sufficiently closely related to animals and humans that they are able to correctly process and configure both animal and human proteins. Their seeds and fruits also provide sterile packaging containers for the valuable therapeutics and guarantee a certain storage life.
Global demand for pharmaceuticals is at unprecedented levels, and current production capacity will soon be overwhelmed. Expanding the existing microbial systems, although feasible for some therapeutic products, is not a satisfactory option on several grounds. First, it would be very expensive for the pharmaceutical companies. Second, other proteins of interest are too complex to be made by microbial systems. These proteins are currently being produced in animal cell cultures, but the resulting product is often prohibitively expensive for many patients. Finally, although it is theoretically possible to synthesize protein molecules by machine, this works only for very small molecules, less than 30 amino acid residue in length. Virtually all proteins of therapeutic value are larger than this and require live cells to produce them. For these reasons, science has been exploring other options for producing proteins of therapeutic value.
Disadvantages
While molecular farming is one application of
genetic engineering, there are concerns that are unique to it. In the case of genetically modified (GM) foods, concerns focus on the safety of the food for human consumption. In response, it has been argued that the genes that enhance a crop in some way, such as drought resistance or pesticide resistance, are not believed to affect the food itself. Other GM foods in development, such as fruits designed to ripen faster or grow larger, are believed not to affect humans any differently from non-GM varieties. In contrast, molecular farming is not intended for crops destined for the food chain. It produces plants that contain physiologically active compounds that accumulate in the plant’s tissues. Considerable attention is focussed, therefore, on the restraint and caution necessary to protect both consumer health and environmental biodiversity.
There are also problems associated with the use of plants as protein
bioreactors. Plant proteins have different sugar residues from human or animal proteins. Freiburg-based greenovation Biotech GmbH, in cooperation with Professor Ralf Reski’s research group at the University of Freiburg, has shown that this problem can be solved through the use of Physcomitrella patens. Because the scientists cultivate the moss in tube-shaped photobioreactors in a liquid medium, they have no worries that the genetically modified mosses might be released into the environment.
Attention is now shifting from basic research towards commercial exploitation, and molecular farming is reaching the stage at which it could challenge established production technologies that use bacteria, yeast and cultured mammalian cells. In this review, we highlight not only recent progress in molecular farming and its potential for commercial drug development and production, but also the regulatory control, biosafety and political impacts of the technology, and its related intellectual property (IP) issues.

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