UC Davis

Plants represent a set of richly diverse and genetically tractable sources for high-value natural and recombinant products that can be used to support human health and industry. This work discusses the production of high-value recombinant products in plants, which is formally termed as plant molecular pharming (PMP), through the lens of the manufacturing techno-economics and applies these insights to the experimental development of plant-based pharmaceutical production technology. PMP must overcome significant challenges as a set of alternative manufacturing platforms. Of primary importance, particular emphasis is required to contextual PMP results in comparison to those of more traditional platforms (e.g., mammalian cell culture, bacterial fermentation) and in terms of economic impact. To encourage the proliferation of such critical context for the field of PMP, we describe a general method for techno-economic analysis of plant-based manufacturing in Chapter 3. We employ this techno-economic method to explore several different opportunities for plant-based manufacturing. In Chapter 4, we collaborate with industry partners to simulate the production of antimicrobial proteins in leafy green plants to respond a food safety-driven demand to protect against high-risk pathogens in a cost-sensitive and antibiotic resistance-concerned product landscape. In Chapter 5, we simulate scale-up of lab-scale results to evaluate the commercial potential of metabolically-regulated semicontinuous bioreactor production of biopharmaceuticals in transgenic rice cell suspension cultures. In Chapter 6, we approach a main barrier facing outdoor field-grown plant-based manufacturing, namely variation in plant quality driving process variation, by introducing uncertainty quantification to techno-economic simulation of large-market natural and biotechnology products in an outdoor field-grown plant system. After having evaluated manufacturing in several different established markets and environments for PMP, we use these general insights to consider and introduce the potential of PMP for supporting human health in the upcoming and uniquely resource-limited environments of deep-space exploration in Chapter 7. After identifying pharmaceutical purification as a bottleneck in the realization of a robust pharmaceutical foundry for space exploration, we evaluate the current state of terrestrial pharmaceutical purification costs in the space-relevant costing framework of equivalent system mass in Chapter 8. Lessons learned around the constraints of pharmaceutical purification in limited-resource environments, including deep-space exploration and rural terrestrial environments, motivated the experimental development of a plant virus-based immunosorbent nanoparticle (VIN) technology as a simple and bioregenerable reagent for the purification of therapeutic monoclonal antibody and Fc-fusion protein drugs using affinity sedimentation or, when coupled with magnetic particles, affinity magnetic separation in Chapter 9. We then further explore VINs as functional elements within larger system arrangements to exploit novel advantages of the virus-based nanomaterial structure and overcome limitations of the existing methodologies. In Chapter 10, we present entrapment and utility of VINs in silica sol-gel matrices by pore confinement, representing a novel system configuration for virus-based nanomaterials (VBNs) in general. In Chapter 11, we present a similarly novel process integration of capture, concentration, and diafiltration steps of pharmaceutical purification by circulation of VINs within a tangential flow filtration retentate loop. Having developed VINs for limited-resource secondary purification, in Chapter 12 we investigate a novel design for a 3D-printed hand-powered centrifuge that is capable of initial clarification steps of pharmaceutical purification. Lastly, in Chapter 13 we conclude and summarize a series of promising yet incomplete research investigations including the purification of VINs with the emerging technology of monolithic chromatography, an exploration of selective pressures to maintain VIN genetic stability over consecutive infection-based production cycles, development of a method for antibody-mediated capture of arbitrary proteins using VINs, important considerations for novel VIN design at the level of the three major structural components, and a novel strategy for the early-stage dynamics of plant cultivation on Mars.