Tiny blood vessels expel clots by force
Mouse study uncovers new way capillaries keep flow going
Tiny blood vessels in the brains of mice have a novel way of dealing with clots — they pack them up and shove them out, right through the vessel wall. This never-before-seen clearance maneuver, reported May 27 in Nature, gets blood flowing again and prevents cell death in nearby brain tissue.
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The new study also found that as mice age, their ability to evict clots deteriorates. Unchecked blockages in small vessels can cause tiny areas of damage to the brain, a process that may be related to the onset of age-related dementia.
Researchers suspect the same kind of clot clearance might happen in humans. “Our vessels are being cleared up on a minute-by-minute basis, which is a great new finding and very exciting,” comments neurologist Costantino Iadecola of the Weill Cornell Medical College in New York City, who was not involved in the study.
Until now, researchers knew of only two ways for blood vessels to dispel clots: Pulsing blood could simply wash the clot away or clot-busting enzymes could dissolve it. These tactics usually work well in large vessels, but small vessels have a harder time pushing clots along. Microvessels, which include capillaries, have diameters of about 20 micrometers or less, leaving them vulnerable to blockages by just a few dead blood cells, a little chunk of cholesterol or a calcium plaque.