Understanding the impact of the engineering environment on transient transfection and process scale-up

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Transient gene expression (TGE) is traditionally used for rapid production of recombinant proteins to support preclinical studies during drug development. This technology involves introducing plasmid DNA into mammalian cells which then express the protein of interest over a limited period of time, typically two weeks. In recent years, there have been some advances in this technology which have led to an increase in titres from mg/L to g/L. These advances, combined with a robust, scalable and well defined process, provide an opportunity to explore TGE as an alternative tool for rapid production of clinical material (e.g. in a pandemic situation or in the context of personalised medicines). The purpose of this research is to elucidate the effect of transfection agent addition (volume, concentration etc), agitation mode, bioreactor geometry and operating conditions on cell growth, DNA uptake, and productivity in a transient transfection process and apply the findings to define an optimal scaling methodology valid up to 200L scale. The proposal is to study the process using scale-down bioreactor systems that most accurately reflect the geometry and flow conditions This builds upon scale-down models and fluid dynamics characterisation methods already available at UCL (see below) to enable rapid progress and generation of results. The doctoral candidate will contribute to the project and will focus on the following objectives:Improve process understanding through advanced engineering characterization in customised systems. Mixing kinetics will be evaluated for different operating conditions using a model system based on current processes, in both rocked and stirred bioreactor configurations, and the impact of fluid rheology and feed location will be evaluated using scale-down mimics of the industrial systems.Establish optimum transfection conditions in specified bioreactor geometries. This will also enable reliable scale translation of transfection conditions between different bioreactor geometries i.e. wave to stirred configurations.Conduct biological verification experiments at scale. A transient transfection process model will be established with associated analytics and experiments will be run using agitation strategy, aeration and feed location as informed by the characterization studies.This project will be part of the UCL-AstraZeneca Centre of Excellence (CoE) that is a joint collaboration between University College London (UCL) and AstraZeneca. The centre's aim is to generate a set of predictive decisional tools for both upstream and downstream biopharmaceutical processing activities. This involves the application of micro-scale and high-throughput studies involving correlation development, multivariate data analysis (MVDA), process economics and discrete-event optimisation. The candidate will join a team of PhD and postdoctoral researchers working in the CoE across upstream and downstream processing as well as modelling tools. The project will be hosted by the department of Biochemical Engineering at University College London in collaboration with AstraZeneca sites across Cambridge (UK) and Gaithersburg (US).