Provision of a MALDI-MSI Platform for Biomedical Analytical Imaging

Mass spectrometry (MS) is a powerful analytical technique that is widely used to identify compounds from a vast array of materials and to study biological molecules and relate them to function. Frequently we compare samples to understand the differences between normal and diseased or treated conditions, for example healthy tissue compared with tissue infected with a naturally occurring pathogen, for example bacteria or a virus. Understanding the molecular responses to infection are key to implementing treatments.

To carry out MS experiments, samples such as bacteria or cells are normally broken down as a whole and compounds extracted for analysis. Whilst extremely sensitive at identifying the molecules present, this method loses the spatial location of the compounds; they may be distributed differently in different areas.

Mass spectrometry imaging (MSI) is a technique that allows characterisation of biological molecules across surfaces. A laser is fired at a very small area on the surface of a sample to generate charged molecules (called ions) from that position, and these are analysed by the mass spectrometer. The sample is moved very slightly, and the laser fired again. In this way we can detected analytes across the surface and build up an image-map. This will allow us to relate the position of biological molecules to function and will be a great improvement on the equipment already available to us.

We propose to use this equipment undertake projects aligned with MRC research portfolio and priorities in themes such as antimicrobial resistance, immunity and infection through the life course, and neurodegeneration supporting existing MRC projects and planned MRC submissions. The project will also support the development of research technical professionals.

Matrix-assisted Laser Desorption/Ionisation mass spectrometry imaging (MALDI-MSI) is a label-free technique which provides comprehensive and unbiased characterisation of biological surfaces. A thin sample section is mounted on a metal-coated glass slide, evenly coated with an organic matrix, and data is acquired by firing a laser at the surface of the tissue, where the energy is absorbed by the matrix molecules, which are ionised along with co-crystalised biomolecules and measured using a mass spectrometer. Sampling laser spots across the entire surface allows the creation of an image-map of the detected analytes.

To carryout MALDI-MSI effectively, sample preparation, matrix application and analytical measurement all need to be correctly addressed, and so we have requested two pieces of equipment that will work together. An atmospheric pressure MALDI ion source will leverage two existing mass spectrometers (an Orbitrap Fusion tribrid and a Quantiva triple quadrupole), making efficient use of resources, and allowing access to a range of analytical techniques not possible on a single technology platform. A matrix-sprayer will be used to deliver uniform and consistent matrix coating critical for high resolution imaging and quantification of analytes.

The Proteomics Research Technology Platform (RTP) at the University of Warwick seeks to establish a Matrix-assisted Laser Desorption/Ionisation Mass Spectrometry Imaging (MALDI-MSI) platform to greatly strengthen our analytical capabilities for small molecules, metabolites and lipids. Metabolite MALDI-MSI will be a new direction for the Proteomics RTP but we will collaborate closely with research groups to establish this technically challenging area in MRC remit areas including antimicrobial resistance, infection and immunity, neurosciences and mental health and molecular and cellular medicines.