Image shows a cluster of mitochondria under the microscope

Under the microscope: mitochondria

Mitochondria. A word you might remember from school biology and probably put in a box with the Pythagorean theorem and the French word for pencil case – a box labelled ‘never to be used again’.

Well here we are, again, and mitochondria look like they might be worth revisiting.

Mito-what?

! Mitochondria, described in every text book as ‘the powerhouse of the cell’, can be thought of as microscopic digestive systems. They take in nutrients, break them down and create energy rich molecules for the cell to use.

Just like any cell in the body, nerves contain mitochondria to generate energy. In progressive MS, dysfunction of the mitochondria and a resulting depleted energy supply is thought to contribute to degeneration of nerves and subsequent disability.

Let’s take a closer look

Nerves are surrounded by a fatty protective coating called myelin. In MS, immune cells attack the myelin causing damage. This is referred to as demyelination and it is responsible for MS symptoms. In progressive MS, the amount of myelin being damaged outweighs that being repaired. When myelin is damaged, the energy demand of the nerve increases and the cell body (the brain of the nerve), which is responsible for producing mitochondria, sends more to the area of damage to compensate.

The problem is that in MS, it seems the immune system’s attack also results in mitochondrial damage. The cell body starts to produce faulty mitochondria which get sent to the area of damage where they don’t work as well as they should. These mutants produce harmful molecules which cause further damage.

If a cell body is no longer capable of supplying the nerve with healthy mitochondria then the nerve may not be able to meet the increased energy demand imposed by demyelination. So in effect the immune system is launching a double attack which can eventually lead to nerve damage and disability.

Targeting mitochondria for treatment

So can we target mitochondria with a treatment to help people with progressive MS?

This is a question Dr Don Mahad at the University of Edinburgh and researchers from America, Canada and Italy will be trying to answer. They have received funding from the Progressive MS Alliance (PMSA), an international collaboration whose sole aim is to speed up the development of treatments for progressive MS. Over the next five years the alliance will be investing £17.5 million into this collaborative effort.

Dr Mahad’s project will be exploring nerve damage in relation to mitochondrial injury and a transition to progressive MS. If the study finds mitochondrial dysfunction is linked to the onset of progressive MS then the next step will be to develop therapies targeting mitochondria to test in a clinical trial in the future.

Dr Mahad said the work of the Progressive MS Alliance is really exciting: “The Alliance is giving a great deal of hope to people with progressive MS in that it is being recognised as a research priority. It is also offering an opportunity for collaborations between international groups". We look forward to seeing this study progress and, for now, we’ll be moving mitochondria into a box labelled ‘might come in useful’.