The growth of new blood vessels from existing vessels, familiar to most as angiogenesis or neovascularization, has acquired an importance that would have been difficult to imagine a few years ago. The proven efficacy of recently approved drugs that block angiogenesis in tumours and age-related macular degeneration has heightened the visibility and relevance of research on blood vessel growth and regression. The promise of factors that stimulate functional revascularization of organs, starved of their blood supply by ischaemic vascular disease or other conditions, is also increasing. Success in the clinic has shifted into high gear the search for even more efficacious drugs. How can these agents be identified, screened and tested? How can their mechanism of action be determined? The seemingly ideal approach for evaluating agents would be through pre-clinical models of the targeted diseases. However, few pre-clinical models faithfully mimic human disease. There-fore, the search continues for faster, easier, more relevant ways of assessing agents that stimulate or inhibit angiogenesis
