Small vessels are big problem in stroke

Capillaries ― the smallest of blood vessels ― can remain clogged hours after a stroke, worsening brain damage, reports a study in this week's Nature Medicine. The findings could help to identify a new target in the treatment of stroke.

Studying mice, Turgay Dalkara and his colleagues found that, after stroke, pericytes ― cells in the walls of capillaries ― remain contracted hours after blood flow to the brain is restored, obstructing the transit of red blood cells. This effect depends on the production of free radicals by the blood vessel wall; if production of free radicals is blocked, pericyte contraction is relieved, improving survival of the brain tissue.