Evaluation of cell-free mtDNA as a predictor of risk to diabetic nephropathy

This project utilises a number of patient cohorts: a) The KingsDiab cohort, currently comprising of >500 blood /urine samples collected by The Malik lab since 2009, The GSTT Diabetes clinics, in collaboration with Professor Gnudi. The plasma and serum samples are being used to evaluate mtDNA as a risk marker b) The Pima Indian cohort from Arizona, USA (Dr Robert Nelson), a longitudinal study of diabetes and its complications. Samples collected between 1965 and 2007, with follow up data available until Dec 2013. Baseline serum and urine samples are being used to determine if cell-free mtDNA correlates with risk of DN progression in this cohort. c) The SURDIAGENE cohort, in Collaboration with Professor Pierre-Jean Saulnier at Université de Poitiers, Paris France, we are analysing blood samples from patients in with diabetic nephropathy to determine the mtDNA content in cross-sectional and longitudinal studies.

Methods to study mitochondrial damage in fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is an increasingly prevalent and underdiagnosed disease affecting more than 29 million Europeans in which diet-induced accumulation of hepatic fat can cause permanent liver damage with serious consequences. NAFLD has a strong association with diabetes, obesity and metabolic syndromes and has been associated with diet. Clinical symptoms only surface at late stages of the disease, when it is no longer treatable. Untreated, NAFLD can lead to cirrhosis and hepatocellular carcinoma, culminating in liver failure. Our lab is part of the mtFoiegras project which is a collaboration between industry and academia based in 7 different EU countries, aiming to develop non-invasive, accurate, detection of NAFLD. Our remit it to develop methods to measure mitochondrial function in healthy and NAFLD patients and model systems. Our lab is developing mtDNA based methods to detect cell-free mtDNA in collaboration with Mediagnost, Germany, and to understand the mechanisms of mitochondrial damage in collaboration with Professor Mariusz Wiecowski, Poland.

• Mitochondrial damage in fatty liver disease

Development of an in-vitro model system to test compounds for the prevention of diabetes induced mtDNA damage in the retina

Funded by an MRC-DTP PhD studentship. Primary and transformed cell lines are being tested for high throughput compound screening by using mtDNA changes as a primary endpoint and mitochondrial respiratory chain damage as a secondary endpoint.

Development of an in-vitro model system to test compounds for the prevention of diabetes induced mtDNA damage in the kidney

Primary glomerular mesangial cells and transformed tubular cells lines are being used to test nutraceuticals for the prevention of mtDNA damage induced by hyperglycemia.

Development of methods to detect mtDNA damage

Ongoing work conducted by existing PhD students, MSC and project students. We have developed a number of methods to measure mtDNA damage including the surveyor nuclease method, a PCR based method and we are currently using next-generation sequencing (Funded by Fight for Sight Charity) to sequence mtDNA from >90 patients.

• Methods to determine mtDNA damage

The role of mitochondrial damage in neonatal brain injury

A collaboration with Dr Claire Thornton (The Royal Veterinary College) and Dr Divyen Shah (Queen Mary University of London), looking at the role of brain mitochondrial damage in neonatal brain injury

The evaluation of NSA2 in diabetic nephropathy

Funded by a China Scholarship Council award. This project will evaluate a novel biomarker for diabetic kidney disease. One of the candidate genes we identified, NSA2, turned out to be very highly conserved and our evidence strongly suggests that it is a novel biomarker of diabetic nephropathy. We postulate that renal NSA2 expression could be a potential therapeutic target as it seems to be a glucose-induced gene which is upstream of the pathogenic TGF-β1 pathway. This project will utilise immunohistochemistry and qPCR from patient samples.

Evaluating mitochondrial DNA mediated mitochondrial dysfunction in the pathology of non-diabetic and diabetic Alzheimer's disease

Diabetes can increase the risk of Alzheimer’s disease (AD) through unknown mechanisms. Mitochondria are cellular organelles which produce energy and contain many copies of mitochondrial DNA (mtDNA), a small DNA molecule needed for correct mitochondrial function. Damage to mtDNA can cause defects in energy production. The brain requires a large amount of energy to function and contains thousands of copies of mtDNA per cell. We recently reported the loss of mtDNA in the brains of Alzheimer’s disease patients, and we found mtDNA changes in brains of people with diabetes. Future work will test the theory that Alzheimer’s disease is a disease of energy deficiency in the brain caused by loss of, or damage to, mtDNA and develop therapeutic strategies to protect brain mitochondria.

• Mitochondrial DNA, Diabetes and Alzheimer's

Mesenchymal stromal cells improve beta cell function through transfer of mitochondria

Mesenchymal stromal cells improve the outcomes of islet transplantation in animal models of diabetes. We are investigating the mechanisms through which MSCs interact with beta cells to help define the most effective ways to utilize MSCs and their secreted products in clinical transplantation protocols. We have recently demonstrated that MSCs transfer mitochondria to islet beta cells and that this is associated with increased islet cell mitochondrial DNA copy number, elevated oxygen consumption and enhanced insulin secretion. We are now using single cell RNAseq analysis to identify the effects of MSCs on islet cell gene expression, and we are exploring the mechanisms through which MSCs physically transfer mitochondria to islet cells.

• MSC-Donated Mitochondria Increase Functional Viability of Islet Beta Cell Transplantation for Treating Diabetes