The endothelium – a thin layer of cells lining every blood vessel – plays a pivotal role in regulating blood flow, blood clotting, and inflammatory responses. Research suggests that ME/CFS may involve damage to the endothelium leading to endothelial dysfunction (improper functioning of the endothelium), which contributes to disease manifestations. Below are articles we have written on endothelial dysfunction in ME/CFS – https://www.meresearch.org.uk/endothelial-dysfunction-in-me-cfs-our-articles/