Fast and Flexible Imaging of Excitable Tissues

Optical microscopy is an essential tool in biology. However, biomedical researchers are limited in the types of problems they can address with the imaging tools available in the vast majority of laboratories. Our understanding of the way in which complex tissues such as the heart and brain function is confined by the capabilities of commercially available light microscopes. Specifically, the limited speed with which cells and other features of interest can be imaged within a three-dimensional volume restricts our understanding of the electrical communication between networks of cells which occur on a broad range of time scales. Acquiring image data from the entire tissue volume is slow and leads to a secondary problem of processing the vast quantities of data to isolate those cells and networks of interest. These technical constraints limit the range of behaviour that can be observed in both healthy and diseased tissue.

This project will for the first time give researchers the ability to efficiently capture user-defined features of interest within a three-dimensional tissue volume. Light sheet microscopy sends a pencil of light into the sample and rapidly sweeps this back and forth to create a sheet of light. A detection lens then focuses on this sheet of light to relay the specimen image back to the science camera. However, by scanning the focus of the detection lens in concert with tilting the sheet of light, it is possible to image the specimen over a wide range of angles without the need to adjust the position of the camera or the detection lens. Previously, to capture two cells within a specimen that are located at different depths, the microscope would capture many images covering the range of depths between the two objects. Much of this information would not be useful. By using a tilted illumination plane, it is possible to capture both cells in a single image. This has several benefits: (i) the data required to see both cells is much smaller and easier to manage (ii) the data does not need to be processed in a computer before being able to see both cells clearly (iii) because the cells can be captured in a single image, they can be observed at much greater speed. This last point is particularly useful when trying to measure electrical communication between two cells, which can happen in just a few milliseconds.

Observing short time scale communication between heart and brain cells is crucial in furthering our understanding of how disease develops and progresses. By providing flexibility in the way microscopes capture images it will provide a new window into the normal behaviour of these excitable tissues and thereby provide clues as to how to limit or stop disease progression through medical intervention.

Society as a whole will benefit from a deeper understanding of the processes that determine the health of excitable tissues. Cardiology and neuroscience define the two main areas of excitable tissue research. Our lack of basic understanding in these fields limits our ability to tackle major future health challenges: cardiovascular disease accounts for 27% of all deaths in the UK, with an estimated 7 million people living with cardiovascular disease. This alone has an estimated economic burden of £15 billion each year in the UK (British Heart Foundation Statistics). There are also 152,000 strokes each year in the UK, with over a third of the 1.2 million stroke survivors being dependent upon family or friends (Stroke Association statistics). Delivering a tool capable of efficiently imaging excitable tissue networks will provide an enabling step that will benefit the vast majority of researchers working in these fields. This project will allow research groups in industry and academia to capture signalling events in excitable tissue in two- and three-dimensional sections at high spatial and temporal resolution. This information will be critical in discriminating between healthy and pathological patterns of activity and identifying effective treatments sooner.

Wider research community: The RF-LSM system will be made available to researchers for up to 12 weeks each year. This will stimulate the development of collaborative projects across a wide range of disciplines in both industry and academia. Preliminary data will be acquired to demonstrate the additional value that the RF-LSM system has brought in comparison to conventional imaging systems and promote new basic science discoveries.

UK Commerce: Biomedical imaging remains a key strength in the UK. Any foreground IP developed during the lifetime of the project will be protected through the Innovation Impact and Business (IIB) team at the University of Exeter before being made available for licensing to interested parties. An ongoing relationship with companies with interests in related technologies will be maintained through a series of quarterly meetings.

Public engagement: The outcomes of the project will be made public through social media accounts held by the host institution. Publication in peer-reviewed journals will disseminate findings to the research community. Data will be shared in an accessible format through the Exeter University data repository, Open Research Exeter (ORE) to stimulate interest in biomedical research and relate the key project goals to a wider audience.

Interdisciplinary training: The researcher employed on this project will have multiple opportunities to extend their inter-disciplinary training. Being based in the Biomedical Physics group, the researcher will have access to a wide range of facilities from wet labs to laser laboratories to high performance computing. The researcher will encounter fellow postdoctoral researchers from a wide range of fields including MRI imaging, molecular vibrational imaging, tissue spectroscopy and biomechanics. There will be multiple opportunities for the researcher to enhance their translational skills in writing and presenting scientific data through courses run by the College of Engineering, Maths and Physical Sciences (CEMPS) at the University of Exeter.