Red blood cells go out with a bang

What is it about?

Red blood cells lose their organelles and nucleus during maturation. This serves to optimise oxygen-transport capacity; however, it also leaves them without the capacity to generate new proteins and limits their capacity to generate molecular energy. As a result, their 120-day lifespan is characterised by progressive loss of membrane and cell volume. It is still mysterious how old red cells get removed at the end of their lifespan, given they lost the tools for controlled self-destruction. Our study shows that when old RBC experience mechanical forces for a prolonged time, such as when they become trapped at sites of cell removal like the spleen, they accumulate calcium-ions. This forces the cell to expend lots of energy to transport calcium-ions back to the exterior medium, until a critical point is reached at which there is no energy left. Then, old red blood cells abruptly swell until they burst, leaving behind only the cell membrane.

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Photo by Aakash Dhage on Unsplash

Photo by Aakash Dhage on Unsplash

Why is it important?

Timely removal of red blood cells is critical for the body because the oxygen-carrying capacity of old red blood cells diminishes, while their fragility and stickiness increases. Sticky red blood cells remaining in circulation would increase the risk of unwanted clot formation and keeping fragile cells in circulation carries the risk of uncontrolled cell destruction within the cardiovascular system. When red cells are destroyed in the vasculature, they release toxic chemicals that are extremely harmful to bodily tissues. Thus, deciphering how red cell death and removal is controlled is key to treating conditions in which red blood cells are removed excessively (e.g., anaemia) or prematurely.

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