Visual identification, analysis and modelling of sterilising grade filtration for liposome enveloped products

Bioprocess challenge the project seeks to address:
Sterile filtration is essential to the manufacture and safety of biological medicines. The performance of these filtration systems is an industrially relevant challenge that continues to evolve along with next generation therapeutics including viral vectors and liposomes. These products can present difficulties during sterile filtration due to their relatively large size leading to retention within the filter structure. The increasing importance of liposomes has been highlighted by the success of Covid-19 mRNA vaccines which are enveloped and delivered in liposomes. In this project we will combine the high-resolution imaging techniques of confocal microscopy and x-ray computed tomography to measure the means of entrapment for biological components within the filter membrane. Understanding these mechanisms will enable a rational approach to determining operating conditions, membrane type and formulation conditions for sterile filtration of these products.


Objectives:
- Develop imaging approaches to visualise feed material retention for liposome products, formulations in a range of filter types whilst minimising sample interference
- Identify different foulants in complex formulations as they pass or block the filter
- Combine information with complementary techniques to determine where and why fouling is occurring to develop predictive models
- Apply the knowledge gained to various Pall systems, for example pleated sheet cartridges and TFF systems to demonstrate robustness of the research project

Project Description:
Deterioration of performance during sterile filtration of lipid enveloped products e.g. mRNA vaccines is a commonplace issue for industrial scale bioprocesses [1, 2]. At UCL and within the Pall-UCL Centre of Excellence various high-resolution imaging techniques have been successfully used to visualise separation media, including X-ray CT, confocal microscopy, electron microscopy and focused ion beam microscopy. The objective is to characterise the structural features of these materials that determine their bioprocess performance [3-5]. This EngD aims to apply these methods in order to understand Pall sterile filtration separation membrane systems.

Each imaging technique has inherent advantages and limitations, we aim to complement relevant approaches to maximise information gathered. For example combining the capabilities of X-ray CT to measure the 3D structure of the membrane with confocal microscopy to identify fluorescently tagged biological components [5] enables the identification of the regions where those components are trapped within a membrane. These can then be correlated with structural features such as an internal pore size decrease or tortuosity increase. The research will combine the information from these various techniques in order to build towards a mechanistic model [6] to predict sterile filtration membrane performance for liposomes.
Investigating and comparing multiple sterile grade membranes and liposome types during this project will be used to deepen this mechanistic understanding. We are able to make use of the latest microfluidic liposome synthesis technology (developed by Precision NanoSystems) within the project to further this objective.

The CDT has a proven track record of delivering impact from its research and training activities and this will continue in the new Centre. The main types of impact relate to: (i) provision of highly skilled EngD and sPhD graduates; (ii) generation of intellectual property (IP) in support of collaborating companies or for spin-out company creation; (iii) knowledge exchange to the wider bioprocess-using industries; (iv) benefits to patients in terms of new and more cost effective medicines, and (v) benefits to the wider society via involvement in public engagement activities and impacts on policy.

With regard to training, provision of future bioindustry leaders is the primary output of the CDT and some 96% of previous EngD graduates have progressed to relevant bioindustry careers. These highly skilled individuals help catalyse private sector innovation and biomanufacturing activity. This is of enormous importance to capitalise on emerging markets, such as Advanced Therapy Medicinal Products (ATMPs), and to create new jobs and a skilled labour force to underpin economic growth. The CDT will deliver new, flexible on-line training modules on complex biological products manufacture that will be made available to the wider bioprocessing community. It will also provide researchers with opportunities for international company placements and cross-cohort training between UCL and SSPC via a new annual Summer School and Conference.

In terms of IP generation, each industry-collaborative EngD project will have direct impact on the industry sponsor in terms of new technology generation and improvements to existing processes or procedures. Where substantial IP is generated in EngD or sPhD programmes, this has the potential to lead to spin-out company creation and job creation with wider economic benefit. CDT research has already led to creation of a number of successful spin-out companies and licensing agreements. Once arising IP is protected the existing UCL and NIBRT post-experience training programmes provide opportunities for wider industrial dissemination and impact of CDT research and training materials.

CDT projects will address production of new ATMPs or improvements to the manufacture of the next generation of complex biological products that will directly benefit healthcare providers and patients. Examples arising from previous EngD projects have included engineered enzymes for greener pharmaceutical synthesis, novel bioprocess operations to reduce biopharmaceutical manufacturing costs and the translation of early stem cell therapies into clinical trials. In each case the individual researchers have been important champions of knowledge exchange to their collaborating companies.

Finally, in terms of wider public engagement and society, the CDT has achieved substantial impact via involvement of staff and researchers in activities with schools (e.g. STEMnet), presentations at science fairs (Big Bang, Cheltenham), delivery of high profile public lectures (Wellcome Trust, Royal Institution) as well as TV and radio presentations. The next generation of CDT researchers will receive new training on the principles of Responsible Innovation (RI) that will be embedded in their research and help inform their public engagement activities and impact on policy.