Rethinking how the brain removes waste
The brain does not contain the lymphatic vessels that help other organs get rid of toxins and waste products, leading to speculation about precisely how the brain removes its waste. Some of the brain’s waste products enter the fluid that bathes and protects the brain, known as the cerebrospinal fluid, before being disposed of via the bloodstream. However, recent studies in mice have shown the presence of lymphatic vessels inside the outer lining of the brain, called the dura mater.
IRP researchers, led by Daniel S. Reich, M.D., Ph.D., showed that the dura mater of people and marmoset monkeys contains lymphatic vessels. Spotting lymphatic vessels is challenging because they resemble blood vessels, which are much more numerous. In addition, Dr. Reich’s team found a way to see the lymphatic vessels in the dura mater using magnetic resonance imaging (MRI) and confirmed that lymphatic vessels are present in autopsy tissue through special chemical staining methods.
By visualizing the brain’s lymphatic system, this technique makes it possible to study how the brain removes waste products and circulates white blood cells. In addition, the technique allows researchers to examine whether the brain’s waste removal system is impaired by aging or disease.
Absinta M, Ha SK, Nair G, Sati P, Luciano NJ, Palisoc M, Louveau A, Zaghloul KA, Pittaluga S, Kipnis J, Reich DS. (2017). Human and nonhuman primate meninges harbor lymphatic vessels that can be visualized noninvasively by MRI. eLife. 6:E29738.