====== Angiogenic factor ======
Any of a group of substances present in the circulation (most of which are [[polypeptide]]s—e.g., angiogenin, [[fibroblast growth factor]], [[transforming growth factor]]s and some [[lipid]]s) which play a role in blood vessel formation. Angiogenic factors are increased after myocardial ischaemia.

Biological signals known as angiogenic [[growth factor]]s activate receptors on [[endothelial cell]]s present in pre-existing [[blood vessel]]s. Second, the activated endothelial cells begin to release enzymes called [[protease]]s that degrade the basement membrane to allow endothelial cells to escape from the original (parent) vessel walls. The [[endothelial cell]]s then proliferate into the surrounding matrix and form solid sprouts connecting neighboring vessels. As sprouts extend toward the source of the angiogenic stimulus, endothelial cells migrate in tandem, using adhesion molecules called integrins. These sprouts then form loops to become a full-fledged vessel lumen as cells migrate to the site of angiogenesis. Sprouting occurs at a rate of several millimeters per day, and enables new vessels to grow across gaps in the vasculature. It is markedly different from splitting angiogenesis because it forms entirely new vessels as opposed to splitting existing vessels.

Increased levels of angiogenic factors and tumor vessels in [[astrocytoma]] lead to severe [[peritumoral edema]], while vascular normalization substantially alleviates [[brain edema]] in patients with [[glioblastoma]]
((Batchelor TT, Sorensen AG, di Tomaso E, et al. AZD2171, a pan-VEGF receptor tyrosine kinase inhibitor, normalizes tumor vasculature and alleviates edema in glioblastoma patients. Cancer Cell. 2007;11:83–95.))
((Stiver SI. Angiogenesis and its role in the behavior of astrocytic brain tumors. Front Biosci. 2004;9:3105–3123.)).
----
Aberrant expression of angiogenic factors has been anecdotally documented in [[brain arteriovenous malformation]] (AVM) nidus vessels.

[[Cerebral arteriovenous malformation radiosurgery]] for patients significantly reduced the plasma levels of angiogenic factors. The plasma angiogenic factors may be candidate markers for aberrant [[angiogenesis]] of brain AVM and patient response to radiosurgery.
((Xu M, Liu X, Mei G, Zhang J, Wang W, Xu H. Radiosurgery reduces plasma levels 
of angiogenic factors in brain arteriovenous malformation patients. Brain Res
Bull. 2018 May 9. pii: S0361-9230(18)30136-9. doi:
10.1016/j.brainresbull.2018.05.007. [Epub ahead of print] PubMed PMID: 29752992.
)).