Angiogenesis in brain tumors

Angiogenesis is a complex process regulated by multiple stimulatory and inhibitory factors that are able to modulate the migration and/or proliferation of microvascular cells with the objective of formation of neovasculature from preexisting vessels. It involves well-coordinated steps including production and release of angiogenic factors, proteolytic degradation of extracellular matrix components to allow formation of capillary sprout, proliferation and directional migration of microvascular cells, and the final composition of new vessels [Senger (1996) Am. J. Pathol. 149:1-7]. Angiogenesis is present in a number of hypoxic and/or ischemic conditions in the central nervous system, in particular in infarctions and infectious processes. Angiogenesis also plays an important role in malignant primary tumors. Glioblastomas, the most malignant gliomas in adults, are among the most angiogenic of all human tumors. This review will examine recent data of the role of angiogenic growth factors in the neoplastic and reactive conditions in the brain.