Application of MRI and low-field NMR in biopharmaceutical development

Biopharmaceutical drugs, such as monoclonal antibodies (mAbs), represent a growing class of therapeutics agents, accounting for more than half of the best-selling drugs globally in 2023. Understanding the processes involved in upstream bioprocessing, where mAbs are manufactured by cells, is therefore paramount. To date, nuclear magnetic resonance (NMR) has had limited application in upstream bioprocessing, stemming from the use of high-field NMR systems that require large capital expenditure, specialised facilities, and high maintenance costs. The development of low-field, or benchtop, NMR spectrometers allows for the opportunity to bring NMR outside of these specialised facilities at a much-reduced cost, due to their portable and cryogen-free design. This thesis investigated the use of low-field NMR with respect to upstream bioprocessing. A method for determining the concentration and aggregate content of a protein sample was developed, called Diffusion-Relaxation water NMR (DRwNMR). This utilises the water proton signal, exploiting the change in transverse relaxation rate [R₂(¹H₂O)] and diffusion coefficient [D(¹H₂O)] to give this information. Importantly, the DRwNMR method overcomes the inherent weakness of using water NMR (wNMR), allowing for solely NMR to be used. The study of suspension cell cultures was also carried out. The basis behind R₂(¹H₂O) peaking at the maximal cell growth rate for Chinese hamster ovary (CHO) cell cultures was investigated, and methods of storing samples for later analysis investigated. Here, it was shown that culture aliquots do not require the presence of cells to provide the same peak in R₂(¹H₂O) at the maximal cell growth rate, with freezing samples for later analysis shown to be unsuitable as a storage method. An alternative mammalian cell line (HEK293) was also studied to test the generality of this trend. This led into the development of an NMR-compatible flow loop system capable of monitoring a bioreactor in real-time using R₂(¹H₂O); the system was successfully used to monitor a benchtop bioreactor cell culture over the period of one week. Magnetic resonance imaging (MRI) allows for the determination of hydrodynamic behaviour within a system of interest, enabling the study of the flow field within. The widely used ambr® 15 microbioreactor was studied using an imaging sequence that gave three-dimensional velocity data. By capturing velocity data in three-dimensions, it was possible to determine the turbulent kinetic energy within the ambr® 15, which has not previously been studied in microbioreactors using MRI. Comparison studies utilising impeller speeds higher than previously explored, as well as differing fluid rheology, were carried out, with three-dimensional rendering allowing for greater ease of comprehension and enhanced data visualisation.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2025

Author dc:creator

• Grimes, Mark

Advisor dc:contributor.advisor

• Mantle, Mick

• Nuclear Magnetic Resonance
• Biopharmaceuticals
• Hydrodynamics
• Cell culture

Licence

• https://www.repository.cam.ac.uk/bitstreams/820aff32-b9ce-49b9-b650-66a2364402eb/download
• http://purl.org/NET/rdflicense/allrightsreserved

Language dc:language

eng

Author Identifier

0000-0001-7655-8156

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/391902