Lymphatic cells are the body’s garbage-disposal system: When fats and other waste products leak out of blood vessels, they mop them up so they don’t damage organs. These types of cells have not been seen in the brain, however, so scientists at the University of Queensland in Australia were surprised when they found a new type of lymphlike cell there.
By studying transparent zebrafish, the scientists observed scavenger cells surrounding the brain that clear out cellular waste. The cells are similar to "mato," or lipid-laden, cells in people, which were not previously known to be lymphatic, according to a press release. Ben Hogan, Ph.D., an associate professor in the university’s Institute for Molecular Bioscience, believes similar cells may be active in the human brain as well, protecting it against stroke and dementia by keeping harmful substances out.
Normally, lymphatic cells clump together, forming vessel-like structures that carry fluid, Hogan explained. But in zebrafish brains, “these cells exist individually, independent of vessels and collect waste that enter the brain from the bloodstream,” he said in the release.
Because zebrafish have many of the same cells and organs as people do, the discovery could enhance the study of brain disorders and treatments, Hogan added. The study was published in the journal Nature Neuroscience.
Zebrafish are being deployed in research for a range of diseases, from cancer to diabetes. Last year, scientists at Boston Children’s Hospital used the transparent creatures to visualize the spread of melanoma from a single cell, and in so doing identified genes involved in metastasis that they believe could be targets for new treatments. Researchers at the University of Oregon found a protein in zebrafish that seems to boost insulin production. And a team at Johns Hopkins has developed genetically modified zebrafish embryos that can be used in high-throughput screening for potential new drugs.
The University of Queensland team plans to expand upon their findings by studying how the cells they discovered function in people and how they influence neurological diseases such as stroke and dementia. They are also interested in learning whether existing drugs can directly control the scavenger cells in the brain, Hogan said.