Novel meningeal lymphatic vessels for drainage of cerebrospinal fluid

Abstract

fluid and macromolecules were instead thought to be cleared from the CNS by other routes, such as through absorption into the bloodstream, or through channels running along the outside of blood vessels or nerves to reach the lymphatic system outside the CNS. A few years ago, lymphatic vessels were discovered in the dura mater, the outermost of the three meningeal membranes that envelop the CNS. They were reported to provide a route for immune cells trafficking from the CNS and for clearing CNS waste, and to thus represent potential therapeutic targets for neurological diseases. However, exactly how they might ena-ble drainage from the brain has remained unclear, and whether they even have a role in drain-age has been questioned. Here I demonstrate that meningeal lymphatic vessels at the base of the rodent skull provide a direct route for the clearance of proteins and other large molecules from the CNS to the peripheral lymphatic system. I further characterize age-related changes in these vessels that impair their drainage function and that might contribute to ageing-associated neurological diseases.

Lymphatic vessels around the body drain excess fluid and protein from tissues and serve as a conduit for trafficking immune cells. The central nervous system (CNS) was long thought to lack lymphatic drainage