Table 1.

Myeloid cells employ a number of different mechanisms to facilitate angiogenesis. Specific cell surface proteins allow myeloid cells to congregate efficiently around budding endothelium. Secreted factors include some matrix-degrading enzymes, which degrade the extracellular matrix (ECM), effectively clearing the way for budding vasculature and releasing vascular endothelial growth factor A (VEGFA) from the matrix. Lastly, myeloid cells secrete pro-angiogenic factors that stimulate endothelial cell (EC) migration and proliferation.

Sequestration Proteins	Matrix Degrading Enzymes	Pro-Angiogenic Factors
VE-cadherin (cell surface)	MMP-2,7,9 and 14 (secreted)	VEGFA (secreted)
CD31 (cell surface)	Cathepsin B (secreted)	FGF2 (secreted)
TIE2 (cell surface)		TNFα (secreted)
		TGFβ (secreted)
		PDGF (secreted)
		Neuropilin-1 (secreted)
		CXCL-8,12 (secreted)
		Semaphorin-4D (secreted)