Boston—The activity in age-related macular degeneration (AMD) involves a close association between endothelial cells and pericytes, the latter of which wraps around endothelial cells of the capillaries and venules.
Pericytes regulate blood flow, clear cellular debris, are a key factor in the blood-brain barrier, and stabilize maturation of endothelial cells, explained Elias Reichel, MD, professor of ophthalmology, Tufts University School of Medicine, and vice chairman, New England Eye Center, Boston.
Platelet-derived growth factor (PDGF), a mitogenic factor that is a product of the endothelial cells, fibroblasts, and smooth muscle cells, comes in a few isoforms: A, B, C, and D and there are two receptors, a and b.
PDGF-b is crucial for vasculogenesis, as it initiates proliferation and migration of pericytes, said Dr. Reichel. He added that PDGF-b also is required in cellular division of fibroblasts, and it has roles in wound healing, cancer, and fibrosis.
“PDGF-vascular endothelial growth factor (VEGF) is a vicious cycle,” Dr. Reichel said. “Anti-PDGF drugs and anti-VEGF drugs have different mechanisms of action. Anti-PDGF drugs increase sensitivity to anti-VEGF drugs and have anti-fibrotic activity.