The large pink spot near the top of the blue blood vessel in this image is a leukocyte (white blood cell). The photo is part of a time-lapse video that scientists at the Novartis Institutes for BioMedical Research shot to determine how quickly leukocytes move through the vessels of a mouse. A slow-rolling or motionless leukocyte spells danger.
The team, part of a group that focuses on cardiovascular and metabolic diseases, studies atherosclerosis, which is characterized by plaque buildup in the arteries that can result in heart attack or stroke. Leukocytes contribute to this hardening and narrowing of the vessels. How? They patrol the circulatory system and survey the vessel walls for signs that something is amiss, launching an investigation in response to an inflammatory stimulus. A leukocyte investigation consists of the cell adhering to the vessel wall, migrating to the other side and hanging out to fight a perceived threat. As leukocytes accumulate, the inflammation gets worse, with a variety of cells, lipids and other material ultimately gumming up the vessel.
“The goal is to keep the leukocytes moving, to keep them rolling along the vessel wall so they don’t investigate and cause the local inflammation that leads to atherosclerosis,” says Gordon Turner, a senior investigator in Cardiovascular and Metabolic Diseases.
The team tests potential drug candidates—molecules identified through screens and other experiments—on mice to determine which ones speed up the rolling. The researchers monitor leukocyte activity in the animals’ ears, which are accessible for non-invasive imaging.