Exercise Training in Mitochondrial Myopathy Patients

In last week’s WCMR ‘Research in Progress’ meeting, 1st year PhD student Valeria Di Leo talked to us about her research project that aims to understand the effects of exercise in mitochondrial myopathy patients. Here, Valeria tells us more.

Skeletal muscle is a high energy-demanding tissue, requiring huge amounts of energy for muscle contraction. Energy production is orchestrated through different processes in skeletal muscle, the most efficient of which takes place within the mitochondria. Mitochondria have their own DNA (mtDNA) which tells the cell how to produce important structures needed for this energy production.

Problems with energy production can lead to mitochondrial myopathies, a heterogeneous group of adult-onset progressive disease. A number of different ‘spelling mistakes’ within mtDNA can lead to mitochondrial myopathy. However, patients tend to present with common symptoms that can include progressive paralysis of the extraocular muscle (CPEO), weakness, myopathy and inability to exercise because of a reduced oxygen uptake capability. Unfortunately, there is no current treatment for patients affected by this disease.

Over the last decade, exercise training has been investigated as a potential way to improve mitochondrial function, giving benefits to patients with muscle weakness and exercise intolerance. My project will look at the effects of resistance exercise training on the muscle cells in a group of patients with a deletion in their mitochondrial DNA. The clinical benefit of training has been assessed by members of the WCMR clinical team and skeletal muscle biopsies taken from each patient both before and after training.

Two of the structures important for energy production are more commonly affected in patients with mitochondrial myopathy. This is because the information needed to make these structures is often lost when there is a deletion within the mtDNA. I will look at these structures within skeletal muscle (an example of which is shown in the image above) both before and after exercise to understand whether exercise induces an improvement in mitochondrial function. In addition, my project aims to use powerful technology to gather large amounts of information, in order to identify what improves with exercise, so that we may be able to find a drug that can generate the same effect.