When edible vaccines were first attempted to produce, researchers played on the idea of utilizing transgenic plants as a bioreactor especially for largescale production. Plant-based edible vaccines are easier to handle, do not require complicated storage, and provide a cheaper alternative to vaccine production.
Some of the commonly used transgenic plants as a bioreactor include tobacco, potato, tomato, corn, and rice. Also, transgenic plants have been used to produce bacterial vaccines, viral vaccines, parasite vaccines, and immuno-contraceptive vaccines.
Of all the expression forms of molecular farming, plant cell suspension culture perhaps is the most promising approach to commercial production of biopharmaceuticals. Presently, various recombinant proteins that are used in the production of vaccines, antibodies, growth hormones and factors, and cytokines can be expressed using plant cell culture.
The most widely used plant cell lines for recombinant biopharmaceutical production are those derived from tobacco such as cultivars BY-2 (N. tabacum cv. Bright Yellow 2) cells and NT-1 (N. tabacum-1) cells. Other plant cell lines that were used came from common crop species, such as rice, soybean, alfalfa, carrot, and tomato.
Plant cell culture has been regarded as more advantageous over other expressions system due to the attractive features it offers:
Scaling up cell culture in bioreactors is the most fundamental step that must be accomplished in order to successfully apply plant cell culture for commercial production. While plant cells are cultured in a bioreactor similar to how microbial cells and mammalian cells are cultured for large-scale production, the process is still complicated.
The large size and complex morphology of plant cells must be taken into consideration when scaling up plant cell culture. Plant cells are significantly larger than bacteria, yeast, and mammalian cells, and tend to form cell aggregation. Hence, plant cells are prone to shear stress. In general, when selecting a bioreactor for culture of plant cells, it is recommended that a bioreactor system with extremely low shear stress and adequate oxygen transfer be considered.