Angiogenesis is an important natural process for generation of
new vasculature during embryonic development and in tissue or
wound repair. Angiogenic growth factors, including numerous
cytokines, chemokines and growth factors, activate cells present
in existing blood vessels to proliferate and form new vessels,
as well as to release additional factors into the
microenvironment. While research around this process is
important for diseases characterized by poor vascularisation,
there is ever-increasing research on angiogenic processes in the
development and support of tumorigenesis. Oncogenes can induce
the release of angiogenic factors that recruit and reprogram
other cells, induce cell differentiation, and establish a tumor
microenvironment. Consequently, tumor tissues contain a large
number of endothelial cells, fibroblasts and tumor-infiltrating-
lymphocytes (TILs) that modulate the immune response in the
microenvironment.