VEGF-C acts as a vasodilator and enhances outflow in the porcine distal outflow tract

VEGF-C is generally not known as a vasodilator, unlike VEGF-A. We investigated how VEGF-C affects the structure and function of the distal outflow tract in a porcine eye model, which has tissue characteristics of both blood and lymphatic vessels. We compared VEGF-C perfused anterior chamber segments of enucleated porcine eyes with or without intact trabecular meshwork ™ to control eyes. In Experiment 1, we used SD-OCT to image the real-time changes in the outflow tract within the first three hours of perfusion initiation. We reconstructed them in 3D and analyzed them for vascular volume changes. VEGF-C caused dilation with a 14% increase in intravascular volume in eyes with and without TM. These changes happened within 140 minutes and then plateaued. In eyes without TM, the volume increase was faster than in eyes with TM. The most significant difference between the two groups was at 40 minutes, and it gradually decreased over the next 100 minutes. In Experiment 2, we measured the changes in outflow tract facility under VEGF-C perfusion over 48 hours. In eyes without intact trabecular meshwork, VEGF-C increased the facility by 29.2% after 24 hours and by 28.8% after 48 hours compared to control eyes without TM. We concluded that VEGF-C can cause dilation of the distal outflow tract vessels and improve aqueous humor drainage, regardless of the presence of trabecular meshwork. More research is needed to identify the precise locations of post-trabecular outflow resistance and to establish accurate correlations between these parameters.