Supervisors: Dr David Li / Dr John Casey / Prof Gail McConnell / Prof Will Shu
Diabetes is a growing global challenge; currently 5% of the UK population are diagnosed with diabetes and over 300,000 patients have type I diabetes. Exogenous insulin administration controls the dangerously high blood sugars but in the long term does not prevent complication such as hypoglycaemia, kidney failure, blindness and cardiovascular disease.
Islet transplantation for type I diabetes can result in freedom from insulin injections and reversal of life threatening complications of diabetes (Shapiro et al, N. Engl. J. Med., 2000; Forbes et al, Diabetologia, 2015).
However, widespread administration of this therapy is limited due to the lack of human cadaveric islets and the need for chemicial immunosuppression. Islets are extracted from human donor pancreases by a complex digestion and purification process. Unfortunately 60% of these preparations are not used for transplantation as they are deemed sub optimal by simple light microscopy and live/dead staining.The risks of serious infection, malignancy and kidney impairment mean that islet transplantation is not currently offered to young patients who arguably have most to gain.
These limitations lead to low transplantation efficiency (most islet transplant recipients require islets from multiple donors to restore euglycemia), long waiting-list times and impaired long-term outcomes. To overcome this organ shortage problem, new methods of efficiently producing transplant-ready, encapsulated islets in-vitro are urgently needed.
The Scottish Islet Transplant Programme (an NSD funded collaboration, £1M p.a., between SNBTS, UoE and the Transplant Unit at RIE led by Dr John Casey) is the largest unit in the UK (>50% of UK islet transplants) and now one of the biggest worldwide with excellent clinical outcomes (Forbes et al, Diabetologia, 2015). However, the quality of the islets from donated tissue sources can vary greatly. Currently, optical imaging of 2D islet morphology is routinely used in islet transplantation units to assess the quality of the islets which are ineffective, slow and not quantitative (see Figure below). Even scanning microscopes with stitching or tiling post processing tools do not provide reliable analysis and adequate resolution.
Recently, Prof Gail McConnell (GM) has built an innovative optical lens system (Mesoscope, MRC MR/K015583/1, £1.5M) for 3D imaging of objects up to 6 mm wide and 3 mm thick with depth resolution of only a few microns instead of the tens of microns currently attained, allowing sub-cellular detail to be resolved throughout the volume (McConnell et al., eLife, 2016, DOI: 10.7554/eLife.18659.001). The study will provide a rapid, imaging technique able to image and analyse large groups of pancreatic islets either natural or synthetic (through 3D bioprinting), providing unprecedented detailed analysis for quality control of transplantable islets or the development of 3D bioprinted tissues.
Islets of Langerhans are extracted by enzymatic digestion of human donor pancreata. The process results in islets of varying size and quality and current methods of assessing these isolated islets do not accurately predict post transplant function.
Human islets prepared at by the Scottish Islet Isolation laboratory will undergo imaging by standard 2D microscopy and 3D mesoscopy and characteristics of the islets recorded. Each prep will then undergo in vitro functional assessment at multiple time points to confirm early and late viability. Follow up microscopy and mesoscopy will also be carried out at these subsequent time points to look for structural changes to the islets that correspond with functional changes. In this way we aim to build a predictive model of islet function based on 3D imaging. Uniquely, we will also correlated 3D structural characteristics with post transplant metabolic outcomes in human recipients of the sampled preps.
In addition, this experimental model will also be used to assess 3D printed, encapsulated islets and compare with standard islolated islets.
Supervisors: Prof Stephen Marshall / Prof Duncan Graham / Prof Karen Faulds / Prof Chris Gregory
Conventional Confocal Raman microscopy is able to generate clear images of biological samples based on the molecular vibrations. The technique is a powerful one but the resolution in these images has historically been limited by the diffraction limit of light.
This means that any biological cell structures which exist at a smaller resolution than this limit are currently inaccessible by Raman Imaging.
Recent work between Departments of EEE and Chemistry at Strathclyde has demonstrated that it is possible to go beyond the diffraction limit and this project aims at further developing this super-resolution approach and applying it to biological samples to identify and differentiate sub-cellular structure with molecular detail.
By combining sophisticated state of the art digital image processing algorithms with highly performing Raman instrumentation on a key biological sample, we will demonstrate the ability of our approach to go well beyond current, commonly obtainable spatial resolution using a Raman microscope. We see this as a key technological development to provide a simple and easy to use tool for use in the life sciences. We also envision the application of this tool to bioimaging to open new lines of investigation currently unimaginable due to technical limitations.
The project will be initiated on samples – experimental and clinical – containing extracellular vesicles (EVs) as these subcellular structures hold much promise as diagnostic and therapeutic targets for a variety of diseases and are difficult to image by conventional means. The project will be extended to include imaging of additional cell/tissue structures of potential clinical as appropriate. The technology will allow imaging at a scale not previously accessible by Raman Spectroscopy but which can now be observed, with all of the medical benefits that follow.