Mural cells cover the vasculature and control numerous aspects of vascular function, including control of blood flow, vessel growth/integrity, scar formation, and even regulation of inflammation. However, the term “mural cell” is an umbrella term, as it really refers to a number of cell types that we are just learning how to distinguish.
On larger arteries and arterioles of the brain, mural cells are referred to as smooth muscle cells. They are powerful ring-shaped sphincters that contract and relax to regulate blood flow to the brain. On the capillaries, mural cells are referred to as pericytes, and they look completely different, possessing round cell bodies that protrude from the vasculature, and longer processes with varying shades of complexity. Pericytes are important for blood-brain barrier function, and many other roles that have yet to be teased out.
Why do we care? If pericytes serve such diverse roles, they may be a valuable target to modify vascular dysfunction in diseases such as stroke, Alzheimer’s disease, and traumatic brain injury. A recent paper from our laboratory uses advanced imaging techniques to lay the ground work. It helps us understand what shapes and sizes pericytes might come in, and their organization in the native brain environment.