Endothelial-Pericyte Interactions Regulate Angiogenesis Via VEGFR2 Signaling During Retinal Development and Disease.

PURPOSE: Endothelial-pericyte interaction disruption causes vascular dropout and pathological angiogenesis, severely impacting visual function in ocular microvascular diseases. This study examines VEGF receptor 2 (VEGFR2) signaling in endothelial-pericyte interactions, highlighting VEGFR2 as a potential therapeutic target for promoting pericyte coverage and decreasing vascular leakage in diseased retinas.

METHOD: Cell-cell interactions with VEGFR2 signaling were assessed using isogenic endothelial cells and pericytes from induced pluripotent stem cells. We investigated changes in VEGFR2 signaling resulting from endothelial-pericyte interactions using quantitative Reverse Transcription PCR, western blot analysis, immunofluorescence staining, migration assays, permeability assays, transendothelial electrical resistance measurements, flow cytometry, and three-dimensional collagen gel vascular networks. We validated VEGFR2 as a therapeutic target via intravitreal injection in the oxygen-induced retinopathy mouse model. Treatment effects were evaluated using western blot analysis, immunofluorescence staining, and an FITC-dextran permeability assay to assess protein expression, pericyte recruitment, and retinal vascular function in response to VEGFR2 modulation.

RESULTS: We demonstrate that direct endothelial-pericyte contact, mediated by N-cadherin, downregulates phosphorylated VEGFR2 in endothelial cells, thereby enhancing pericyte migration and promoting endothelial cell barrier function. Intravitreal injection of a VEGFR2 inhibitor in mouse models of the developing retina and oxygen-induced retinopathy increased pericyte recruitment and decreased vascular leakage. The VEGFR2 inhibitor further rescued ischemic retinopathy by enhancing vascularization and tissue growth.

CONCLUSIONS: Our findings uncover a novel mechanism by which VEGFR2 signaling is regulated through endothelial-pericyte interactions, promoting pericyte migration and strengthening endothelial barrier function. These results suggest a pathway that could be harnessed to support the growth of functional and mature microvasculature in ocular microvascular diseases and tissue regeneration overall.