Table 1.

Factors affecting pericyte migration

Regulators of pericyte biology
Molecule	Effect on migration/recruitment	Effect of deficiency	Other functions	References
PDGF	↑	Loss of pericyte recruitment to vessels, microaneurisms, embryonic lethality	Receptor activation can lead to proliferation, migration, survival, VEGF expression, activation of Ras/Rho/Rac, PKC, FAK, ERK	[1, 12, 33–36]
S1P/EDG-1	↑	Defects in vasculature and discontinuous coverage of blood vessels	Regulates cellular response to PDGF and EGF, enhances ECM production	[37–50]
Ang1	↑	Embryonic lethality due to cardiovascular failure, defective angiogenesis, reduced pericyte coverage	Critical factor for blood vessel stabilization, actin remodeling, migration	[12, 15, 51–54]
Ang2	↓	Normal vascular development, lymphatic defect	Angiogenic sprouting in tumors, inversely correlated with pericyte coverage	[15, 55–57]
Sema3A/Nrp	↑	Reduced vessel density, tortuous vessels	Induces vessel stabilization, enhanced pericyte recruitment and content, reduces tumor growth and angiogenesis	[59, 62, 63]
MMP9	↑	Reduced recruitment and vessel association of pericytes	ECM remodeling, growth factor cleavage, vessel maturation, protection against apoptosis	[12, 65–70, 73–75, 78, 79, 101]
TGFβ	↓	Disruption of the vascular network due to disordered interaction between pericytes and nascent blood vessels, deficiency of pericyte coverage	Ubiquitous, promotes expression and flux of ECM proteins	[87–90, 94–96, 137, 138]
ALK1	↑	Embryonic lethality, flawed vascular development, defective angiogenesis	Induces pericyte proliferation and recruitment to vessels	[97, 138]
ALK5	↓	Embryonic lethality, flawed vascular development, defective angiogenesis	Induces pericyte contractile protein expression, promotes ECM production, stabilization of nascent capillary tube	[97, 138]
SPARC	↑	Reduced vessel association of pericytes	Extracellular chaperone for collagen deposition, influences activity of multiple angiogenic growth factors, regulates MMP9-mediated pericyte recruitment, interferes with activation of latent TGFβ, regulates PDGF receptor activation	[6, 31, 98–103, 137]