Question

What is a major economic advantage of producing therapeutic proteins in plants rather than in bioreactors filled with microbes or mammalian cells?

Answer 1

A very advantageous aspect of producing therapeutic proteins in plants is that it does not require a large financial investment to conduct initial studies. Plants can be grown in a greenhouse or even in a biosafety lab if required. The cost of plant maintenance for PMF is low, relative to E. coli, yeast, or mammalian cell expression systems and the source (plant leaves or seeds) for making the recombinant protein is potentially unlimited.

Plant expression systems have several major advantages over prokaryotic and other eukaryotic cell systems in regards to production speed, cost, and safety. Plants can correctly fold and assemble complex proteins, such as secretory antibodies, full size immunoglobulins and the homodimeric vascular endothelial growth factor (VEGF). Human VEGF produced in barley grain has been commercialized for research use.

Plant-expressed human VEGF is used as treatment for thinning hair. Plants also have the capacity to introduce post-translational modifications. The use of plants also eliminates potential contamination of the therapeutic drug with animal pathogens (prions, viruses, and mycoplasmas), thus increasing safety. In general, the cost of PMF-derived products is only 0.1% of mammalian cell culture systems and 2%–10% of microbial systems.