The brain has its own inbuilt processes for mopping up damaging cellular waste — and these processes may provide protection from stroke and dementia. University of Queensland scientists discovered a new type of lymphatic brain "scavenger" cell by studying tropical freshwater zebrafish — which share many of the same cell types and organs as humans.
"It is rare to discover a cell type in the brain that we didn't know about previously, and particularly a cell type that we didn't expect to be there.
"The brain is the only organ without a known lymphatic system, so the fact that these cells are lymphatic in nature and surround the brain makes this finding quite a surprise.
"These cells appear to be the zebrafish version of cells described in humans called "mato" or lipid laden cells, which clear fats and lipids from the system, but were not known to be lymphatic in nature.
"Zebrafish are naturally transparent, which means we can use advanced light microscopes to see directly into the zebrafish brain," Dr. Hogan said.
"Examining the zebrafish brain up close allowed us to find these cells and see how they form and function in detail.
"Normally, lymphatic endothelial cells will group together to form lymphatic vessels to carry fluid, but impressively, in the adult zebrafish brain these cells exist individually, independent of vessels, and collect waste that enters the brain from the bloodstream.
The study was published in Nature Neuroscience and involved researchers from UQ's Institute for Molecular Bioscience, the University of Melbourne, Monash University, and Japan's National Cerebral and Cardiovascular Center.