Cellular gatekeepers of inflammation

When a tissue in the body becomes injured or infected, white blood cells rush from nearby blood vessels to launch an immune response, generally a positive first step in the healing process. But if too many of these first responders arrive on the scene, inflammation can result, so it’s vital that the response is tightly regulated.

A team of scientists led by Anjelica Gonzalez, Ph.D., assistant professor of biomedical engineering, and Jordan S. Pober, M.D., Ph.D., the Bayer Professor of Translational Medicine and professor of immunobiology, dermatology, and pathology, suspected that cells called pericytes, which form the outermost layer of blood vessels, might act as gatekeepers that manage the release of white blood cells into tissue.

The team created a model of blood vessels with discrete layers of human pericytes and endothelial cells, which line the interior of vessels. They found that pericytes precisely and selectively restrict the number of white blood cells that exit vessels into injured tissues. The finding will help researchers build better in vitro models of blood vessels, and could lead to new drugs to treat inflammatory diseases, especially those that affect the lungs, eyes, and skin, which have high levels of pericytes.