High resolution mass spectrometry across the metabolome and lipidome: from single cells to cohorts

Mass spectrometry has revolutionised our understanding of life. It allows scientists to 'weigh' molecules - strictly speaking we measure the mass to charge ratio of a molecule that has lost or captured an electron called an ion. We can do that so accurately that its possible to determine molecular formulas and thus identify molecules according to their mass to charge ratio. Further advances allow us to smash ions into fragments further helping us to determine their structure. One recent advance is mass spectrometry imaging which creates ions directly from tissue and cell samples, and allows scientists to map the distribution of molecules across a tissue. This technology has become so powerful we can now perform this mapping towards a single-cell level.

This equipment grant application is for the purchase of a state-of-the-art mass spectrometry imaging system that can be applied to a wide range of biological and medical applications to understand how diseases arise at the cellular level and spread across tissues. We will be able to detect ions directly from the tissues, allowing us to map how local changes in concentration of molecules influence how a disease progresses. Our applications include studies of fatty liver disease and how this develops to more severe outcomes and how our fat cells try to protect the body when we eat too much. Both projects are important if we are to address the issue of rising obesity levels across the UK and provide treatments for some of the consequences of obesity. We also have projects looking at heart failure and the consequences of age-onset frailty, again major issues facing the National Health Service and society in general. The technology will also investigate how the microbes that live in our gut help to maintain health but may also contribute to disease under certain circumstances. Modifying the front of the system to allow a different way to introduce ions which in turn allows us to image across larger areas, the technology will also be used to understand how changes to the placenta contribute to pre-term and still birth. In addition, the same equipment can be used to perform high throughput mass spectrometry to study large populations. This will be used to examine ageing and its interactions with chronic disease. We will also examine a large cohort of long COVID-19 patients to understand how metabolism contributes to the disease. There is no such technology at the University of Aberdeen to allow these applications to take place. In addition, the equipment will support a variety of researchers across the UK and in particular across Scotland given the lack of similar systems in this region. The equipment will be housed within dedicated laboratory space at The Rowett Institute, University of Aberdeen and maintained by a highly skilled core technical staff. Researchers external to the University will be able to make use of the world class facilities within the Rowett as part of a research hotel arrangement to widen the access to the equipment. In this manner we hope to have a unique research resource for the medical and biological community of the North of the UK.

Mass spectrometry imaging (MSI) has the potential to revolutionise how we view the spatial development of disease by examining metabolites, lipids and peptides in situ across tissue slices and from cells. We are requesting a contribution for a Thermo Exploris 240 Orbitrap mass spectrometer interfaced with an atmospheric pressure matrix assisted laser desorption ionisation (AP-MALDI) source from MassTech and an Advion Nanomate. This combination will provide different modes of single cell metabolomics/lipidomics/proteomics in the form of MSI at a spatial resolution of 5 um across tissue slices or single-cell sorting with lipid and peptide extraction in conjunction with the Nanomate. The Exploris Orbitrap 240 combines fast scanning rates for MSI, high resolution for annotation (up to 240000), high and stable mass accuracy (<1 ppm, >5 days), high sensitivity, polarity switching and exceptional robustness. This makes it the ideal workhorse for a range of single-cell applications and will be the only instrument with this capability in the North of the UK.

Previously, we have demonstrated the heterogeneity of non-alcoholic fatty liver disease and tumour growth in tissues at a spatial resolution of 50 um. The order of magnitude change provided by the requested equipment will be revolutionary, allowing us to image metabolism and peptides in different cell types across tissue samples (e.g. metabolism of infiltrating immune cells). We will also use an Advion Nanomate to interface cell sorting with MS to allow us to profile cells to understand how disease processes arise at the single-cell level. This will be demonstrated across a range of diseases, including type 2 diabetes, atherosclerosis, heart failure, cancer and Alzheimer's disease. We list projects from the Universities of Aberdeen, Cambridge, Edinburgh, KCL, Leeds, Leicester, Strathclyde and UCL to demonstrate the demand. We will also collaborate with EMBL to process the large amounts of data we will produce.