Stroke Vs Brain: Harnessing the Brain’s Survival Skills by Ranya Bechara, Feb 27th 2013
Image credit: http://www.vascularinfo.co.uk
Can we use the brain’s inherent survival mechanisms to develop better stroke treatment? In an exciting new study in Nature Medicine, scientists at the University of Oxford reveal a novel way in which the brain protects itself in response to stroke.
Strokes are a major cause of death and disability worldwide, with 150,000 people affected in the UK every year. Most strokes happen when a blood vessel that supplies blood to the brain is blocked due to blood clots or fat deposits. Once blood is cut off from an area of the brain, brain cells are starved for oxygen and nutrients and start to die within minutes. Current treatments for stroke are focussed on breaking up the clots, improving blood flow to the affected area, and ultimately reducing the brain damage caused by the stroke. However, the so called ‘clot-busters’ are only effective if given within one to two hours of the stroke, so other ways of protecting the brain against stroke damage are in high demand.
In this study, the research team from Oxford University (in collaboration with other researchers from Greece, Germany, and Canada, and the UK) decided to try a new approach. They investigated a phenomenon that has been known for years: some brain cells have an inherent defence mechanism that allows them to survive when deprived of oxygen. These cells are located in the part of the brain responsible for forming memories: a pretty sea-horse shaped structure called the hippocampus. The scientists analysed the proteins produced by these cells and found that the key to their survival is a protein called hamartin. This protein is released by the cells in response to oxygen deprivation, and when its production was supressed, the cells became more vulnerable to the effects of stroke.
Interestingly, the scientists were also able to make other cells more resilient by inducing them to produce hamartin. The study suggests that hamartin works by causing the cell to undergo autophagy, a process by which the cell ‘eats itself’ by using its internal machinery to degrade unwanted or troublesome parts. Autophagy is thought to be a way for cells to survive harsh conditions; it reduces the cells’ need for energy, making them more likely to survive for a while without oxygen. The role of autophagy in the brain’s defence against stroke is still quite controversial, but the study does shed some light on what makes certain cells more resistant than others to damage caused by stroke. By better understanding the brain’s inherent survival mechanisms, scientists hope to eventually design new therapeutics for the treatment of stroke, possibly by using molecules that mimic the effect of hamartin.