All parts of the body generate waste that must be flushed out in order to remove harmful materials, old proteins, and other cellular detritus. Most tissues utilize the lymphatic system to keep clean, but the central nervous system (CNS) does not have lymphatic vasculature and relies instead on a waste clearance pathway known as the glymphatic system. The glymphatic system cleans the cerebrospinal fluid (CSF) that surround the brain and spinal cord and relies on specialized CNS support cells known as glia.
In this issue of the Journal of Clinical Investigation, researchers led by Helene Benveniste at Stony Brook University used MRI to visualize the glymphatic system in rats that had been given a fluorescent tracer. The whole brain images allowed Benveniste and colleagues to identify two key influx nodes in the brain. Additionally, they could measure the rate at which the fluorescent tracer was removed by the glymphatic system. Currently, amyloid plaques and other molecules that accumulate in diseases such as Alzheimer’s and Huntington’s disease cannot be visualized in live patients.
In a companion commentary, Warren Strittmatter of Duke University discusses how this new technology could be used to track the development or progression of diseases in which the clearance of specific proteins is impaired.
TITLE: Brain-wide pathway for waste clearance captured by contrast enhanced MRI
ACCOMPANYING COMMENTARY TITLE: Bathing the brain
Journal of Clinical Investigation