New blood vessels are how disease grows. They're also how it heals.

Angiogenesis is the formation of new blood vessels from existing vasculature. It is essential for embryonic development, wound healing, and reproduction. When dysregulated, it becomes one of the central engines of disease.

In cancer, tumors recruit new vessels to deliver oxygen and nutrients — a hallmark of malignancy first described by Judah Folkman in 1971. In wet age-related macular degeneration, abnormal choroidal vessels destroy central vision. Conversely, in ischemic heart disease, the body's inability to grow new vessels leaves tissue starved of oxygen.