Why do some platelets become harmful, while others are helpful?

The role of the mitochondrial permeability transition pore in procoagulant platelets

Platelets are small blood cells that are both helpful and harmful to us. Helpful, because they enable our blood to clot after injury, so prevent too much bleeding. Harmful, because they also form clots in diseased arteries, leading to heart attacks and stroke. Platelets have different roles during clotting, but we do not yet know how a platelet decides which role to play. Dr Harper believes that the fate of a platelet may be decided by the levels of calcium ions inside it. Calcium levels change inside lots of different types of cells, but he proposes that a release of calcium into the platelet from a compartment within it – called the mitochondria – makes the key difference. The mitochondria is the power station of the cell, and Dr Harper thinks that the calcium release from here is crucial in making some platelets decide to go “all out” to start blood clotting. In this project Dr Harper will study this theory in more detail, in mice. By uncovering what determines whether a platelet will be helpful or harmful, we could identify a way to prevent dangerous blood clotting. Perhaps, in the future, a drug could be designed to alter this decision, and reduce the number of platelets that might cause a heart attack or stroke in people most at risk.