In the past few decades, the plant based expression systems have been recognised as a good alternative to mammalian cells and bacterial cultures for the large-scale production of recombinant proteins. Currently, a huge amount of heterologous proteins are expressed in microbial or mammalian based platforms, which have limited capacity and high upfront costs, particularly in situations where multiple products need to be produced simultaneously. Conversely, plants can be grown inexpensively on an agricultural scale. Plant-derived biopharmaceuticals are cheaper to produce and to store and easy to scale up for mass production. Furthermore, human glicosylated proteins can be expressed since posttranslational modifications occur in plant based platforms. An important implication of plant-made pharmaceuticals is the fact that food vaccines can be produced by expressing the target protein in edible tissues thus representing a valid alternative to shipping vaccines in developing countries. Moreover, the risk of contaminants is lower than in other systems. Historically, the recombinant peptides include antiviral antibodies and immunoglobulins. However, recently other compounds are being synthesized like ß-casein and lysozime, used for children diet additives, and ß- glucuronidase and avidin, used as technical proteins in diagnostics, as well as procollagene, used in regenerative medicine, and finally spider silk proteins for new technologies. Several plant platforms have been proposed due to their characteristics and tested, including food and non-food crops, leafy crops, cereal and legume seeds, fruit and vegetables, aquatic plants. Among them, tobacco is the most used as productive platform while cereals offer the unique advantage of storing proteins in seeds. The present review will present a compendium of the up-to-date information about plant made pharmaceuticals and will compare stable and transient transformation strategies as well as different platforms. The Molecular Pharming technology does not only include the production of therapeutic peptides but also the development of nutraceutical foods by enhancing the amount of valuable secondary metabolites. Among them, carotenoids (as lycopene), abundant in carrots and tomatoes, isothiocyanates, present in Cruciferae, and flavonoids (as quercetin and curcumin) have proved beneficial effects against several human diseases and are considered “health promoting compounds”. Crops biofortification can be obtained through markers assisted breeding or biotechnological approaches. This topic highlights the inconsistency of European legislation on GMOs thus we discuss the updated regulation which is based on a general and ambiguous precautionary principle.
Keywords: GMO, secondary metabolites, plant platform, vaccines, nutraceuticals