Which factor plays a central role in regulating retinal angiogenesis and vessel pruning?

• A. TGF-β
• B. EGF
• C. PDGF
• D. VEGF

Answer: (D)

VEGF is the central regulator of retinal angiogenesis and vessel pruning. When neural tissue in the developing retina becomes hypoxic, it increases VEGF expression. VEGF then binds to receptors on endothelial cells, promoting their proliferation, migration, and guided sprouting to form new capillaries. This VEGF-driven growth creates the forming retinal vasculature in a spatial pattern set by VEGF gradients. As perfusion improves and metabolic demand shifts, reduced VEGF signaling in certain sprouts leads to diminished endothelial survival signals, causing regression of those vessels – the pruning process. Other factors like PDGF help mature vessels by recruiting pericytes, and TGF-β or EGF have roles in remodeling, but VEGF is the primary driver of both the creation and selective reduction of retinal vessels.