Using imaging technology to better understand diseases

An NIHR Newcastle Biomedical Research Centre (BRC) funded project has used a novel imaging technique, which allows closer examination of tissue samples, to better understand the mechanisms behind key age-related syndromes and long-term conditions.

Background

The NIHR Newcastle BRC aims to improve the lives of people living with age-related syndromes and long term conditions and the research it funds seeks to improve the understanding of these conditions and facilitate the development of new treatment options. Monitoring the effectiveness of treatments is a key part of this, something for which tissue samples are often taken. These samples are analysed in the laboratory using techniques that provide insights into disease characteristics, as well as potentially identifying new treatment targets. While current laboratory techniques are highly effective the number of proteins that can be assessed in individual cells within a single section is limited. However, imaging mass cytometry (IMC) broadens the number of proteins that can be examined from 4 to 40, enabling the examination of multiple, discrete proteins within individual cells, greatly increasing the potential insights researchers can gain.

The study

This study, entitled ‘Identifying changes in proteome of single cells using imaging mass spectrometry’, examined skeletal muscle samples for the presence of mitochondrial damage. Studying skeletal muscle is a very effective way to provide accurate diagnosis of mitochondrial disease, because changes that lead to the disease can be identified at the molecular level in these muscle fibres. Common issues related to mitochondrial disease are a reduced ability for cells to generate energy, leading to fatigue, muscle weakness, exercise intolerance as well as a range of neurological symptoms. The ability to examine the proteins responsible for energy production at a single cell level, through IMC, is incredibly powerful when conducting research into mitochondrial disease.

With Newcastle BRC funding, the team behind this study:

• Developed a novel workflow and unique analysis pipeline to apply IMC to skeletal muscle biopsies from patients with genetically-characterised mitochondrial disease.
• By using the IMC technique they could examine a greater number of mitochondrial proteins from fewer tissue samples than they would have been able to using traditional techniques, significantly increasing the data produced.
• This enabled close investigation of the distribution of nine mitochondrial proteins simultaneously within thousands of individual muscle fibres.
• From here, the protein target panel was expanded to include proteins that indicate how the cell may have adapted to the disease.
• Discovering these proteins presents potential new ways to monitor disease progression, the effects of treatments, and potentially can identify new treatment targets.

Professor Doug Turnbull, Principle Investigator for the study commented:

Being able to examine disease characteristics present in skeletal muscle fibres at this level of detail is significant.
Having this technique available is very positive and changes the way in which we can look for disease markers for a broad range of conditions.

A technique with broad benefits

While the project was undertaken in the scientific area of mitochondrial disease, the methods used, now proven to be successful, can be universally applied to evaluate a wide range of skeletal muscle disorders (including Inclusion Body Myositis, HIV-related myopathy and sarcopenia). Furthermore, new protein targets and panels are already being developed to study the effectiveness of exercise as a therapeutic intervention and mitochondrial disease progression.

Understanding neurodegenerative diseases

In parallel, Dr Amy Reeve and her team have developed IMC for use in brain tissue. This project compared brain samples from Parkinson’s disease, mitochondrial disease and healthy young and old controls, to identify disease and age-specific changes in the proteins important for energy production. The image below shows the results of this.

The team have now expanded their IMC panel to allow the investigation of potential disease mechanisms and cellular response to mitochondrial dysfunction. Several academic papers from this study are currently under review or due to be submitted.

Image (left): credit Chun Chen. A stacked image of dopaminergic neurons in the substantia nigra (midbrain) region using imaging mass cytometry.

Linking to other disease areas across the Newcastle BRC

The project has also supported and enabled work to take place across other NIHR Newcastle BRC themes. In Skin and Oral Disease, theme Lead Professor Muzliffa Haniffa has examined the development of fetal liver samples, and in Musculoskeletal Disease, Dr Catharien Hilkens has examined arthritis tissues.

In addition, the technology has been successfully used in a number of other disease areas studied in Newcastle, such as adult liver cancer, prostate cancer, inflammatory bowel disease Crohn’s Disease, and it has also been involved in work that is examining post-mortem tissue samples from COVID-19 deaths.

All of the above projects have also allowed researchers across Newcastle to develop a database of shared protein targets and a vast resource for expansion of IMC to even more tissues and diseases.

Martin Dixon, Chief Operating Officer of the NIHR Newcastle BRC commented:

Providing funding for this project has driven scientific understanding of a range of long-term conditions but has also opened up a brand new way to study how some diseases work, something that can be applied across the areas of experimental medicine we focus on in the Newcastle BRC. Long-term, this project’s outcomes can significantly enhance the efficacy of the way diseases are understood, and therefore treated.

Next steps

In the short-term this work can support more research ongoing in other parts of the Newcastle BRC. For example, one of the target disease areas of Newcastle BRC’s Ageing Syndromes theme is sarcopenia; the decline in muscle strength and mass with ageing. Sarcopenia can lead to a number of severe conditions that dramatically deceases a person’s quality of life as they age, including poor mobility, frailty, increased likelihood of falls, and as a result, higher chances of hospital admission.

By having a more targeted method to understand the mechanisms behind loss of muscle strength and mass as we age, the Newcastle BRC can look at potential treatments and interventions to slow down, or halt the progression of physical decline, and therefore provide better outcomes for us as we age. Work has already begun in this area and provides promising outcomes.

Dr Charlotte Warren, who led on the development of this work during her PhD on the development of imaging mass cytometry for use in skeletal muscle, working alongside Professor Avan Sayer, Professor Turnbull and Dr Amy Vincent, said:

I’m really excited to apply this new technique to give us a better understanding of how muscle changes with age and especially in people with a severe loss of muscle mass, called sarcopenia.

Main article image: credit Dr Charlotte Warren. A close up image of muscle fibres using Imaging mass cytometry (IMC). The image shows levels of mitochondrial proteins in different colours in a single image. Each cell is marked by a white boundary. The colour of each cell dependent on the amount of each protein that is present and variation in colour of each cell arises due to a reduced level, or absence of one or more proteins.