Watch immune cells ‘glue’ broken blood vessels back together

As we age, tiny blood vessels in the brain stiffen and sometimes rupture, causing ‘microbleeds.’ This damage has been associated with neurodegenerative diseases and cognitive decline, but whether the brain can naturally repair itself beyond growing new blood-vessel tissue has been unknown. A zebrafish study describes for the first time how white blood cells called macrophages can grab the broken ends of a blood vessel and stick them back together.