The vasa vasorum in diseased and nondiseased arteries.

The vasa vasorum form a network of microvasculature that originate primarily in the adventitial layer of large arteries. These vessels supply oxygen and nutrients to the outer layers of the arterial wall. The expansion of the vasa vasorum to the second order is associated with neovascularization related to progression of atherosclerosis. Immunohistological analysis of human plaques from autopsied aortas have defined plaque progression and show a significant correlation with vasa vasorum neovascularization. Recent technological advances in microcomputed tomography have enabled investigation of vasa vasorum structure and function in nondiseased large arteries from pigs and dogs. Smaller mammals, particularly mice with genetic modifications that enable disease development, have been used extensively to study the vasa vasorum in diseased vessels. Despite the fact that most mouse models that are used to study atherosclerosis are unable to develop plaque to the extent found in humans, studies in both humans and mice underscore the importance of angiogenic vasa vasorum in progression of atherosclerosis. Those who have examined the vasa vasorum in occluded vessels of nondiseased pigs and dogs find that inhibition of the vasa vasorum makes the animals atheroprone. Atherosclerosis is a multifactorial disease. There is increasing evidence that factors, produced in response to changes in the arterial wall, collaborate with the vasa vasorum to enhance the disease process.