Morphologic Approaches to the Assessment of Angiogenesis

Angiogenesis, the formation of new blood vessels from pre-existing capillaries, plays an important role in tumor progression. The most widely used method of quantifying neovascularity is immunohistochemistry, by which microvessel density is determined using endothelial markers, such as CD34, CD31, and factor VIII. Lectin staining for U. europeus agglutinin also permits visualization of endothelium. Aside from method and antibody selection, clearly defining the object studied (randomly chosen fields vs ‘hot spots’; number of vessels vs number of endothelial cells, etc) and the statistical methods applied are also of fundamental importance. Since many published studies have reached disparate, even opposite conclusions, a consensus agreement on the techniques is needed. In this article, we highlight the current immunohistochemical and morphometric methods currently applied to the study of angiogenesis. The potentials and limitations, as well as the challenges posed by each of these methods are also discussed.