メディエイゴ

Spitting(1) can be a good thing when it comes to(2) blood vessels(3).

Scientists at Northwestern University Feinberg School of Medicine have discovered capillaries(4) have a unique method of expelling(5) debris(6), such as blood clots(7), cholesterol(8) or calcium(9) plaque(10), that blocks the flow of essential nutrients(11) to brain cells(12). The capillaries spit out(13) the blockage(14) by growing a membrane(15) that envelopes(16) the obstruction(17) and then shoves(18) it out of the blood vessel.

Scientists also found this critical process is 30 to 50 percent slower in an aging(19) brain and likely results in(20) the death of more capillaries.

“The slowdown(21) may be a factor in age-related(22) cognitive decline(23) and may also explain why elderly patients who get strokes(24) do not recover as well as younger patients,” said Jaime Grutzendler, MD, senior author(25) and principal investigator(26) of the study and assistant professor(27) of neurology(28) and of physiology(29) at Feinberg. “Their recovery is much slower.”

The study with mice(30), funded by the National Institute on Aging(31) (NIA), will be published May 27 in the journal Nature.

Scientists have long understood how large blood vessels clear blockages: blood pressure(32) pushes against the clot and may eventually break(33) it down and flush(34) it away, or clot busting(35) enzymes(36) rush to(37) the scene to dissolve(38) a blockage.

But very little was previously known about how capillaries clear blockages. The Northwestern study first demonstrated that enzymes and blood pressure aren’t efficient at clearing capillary clots within the critical 24 to 48 hours. Those mechanisms only work half the time and only when blood clots are involved, not other types of debris, particularly cholesterol, which is difficult to dissolve.