Persistence of vascular empty sleeves in choroidal neovascularization after VEGF therapy in both animal models and humans

Choroidal neovascularization (CNV) often recurs during anti-vascular endothelial growth factor (VEGF) therapy; however, little is known about the mechanism of vascular regrowth. Vascular regrowth along the empty sleeves of basement membranes was proposed as a mechanism for recurrence after the reversal of VEGF inhibition in tumors. This study investigated whether the proposed mechanism is involved in CNV during VEGF therapy.

We made two observations using a mice model, as well as patients with CNV. Laser-induced CNV mice were used to examine the vascular empty sleeves of the basement membrane and CNV with the immunohistochemistry of type IV collagen and CD31, respectively. A retrospective cohort study included 17 eyes from 17 patients with CNV treated with anti-VEGF treatment. Vascular regrowth during anti-VEGF treatment was assessed using optical coherence tomography angiography (OCTA).

In the CNV mouse model, the CD31⁺ vascular endothelium area was decreased during anti-VEGF treatment compared with the IgG control (33516.7 ± 10864.7 vs. 10745.9 ± 5755.9 μm², P < 0.05), whereas a significant difference was not observed in the area of type IV collagen⁺ vascular empty sleeve after the treatment compared with the control (29135.0 ± 7432.9 vs. 24592.0 ± 5935.3 μm², P = 0.7). The proportions of CD31⁺ to type IV collagen⁺ areas were significantly decreased after the treatment (38.7 ± 7.4% vs. 17.1 ± 5.4%, P < 0.05). In the OCTA observations, the follow-up period in the retrospective cohort study was 58.2 ± 23.4 months. CNV regrowth was observed in 682 neovessels of the 17 eyes. In group 1, CNV regression and regrowth are in the same form (129 neovessels, 18.9%). In group 2, CNV regression and regrowth are in a different form (170 neovessels, 24.9%). In group 3, CNV regrowth is with a different form without the regression (383 neovessels, 56.2%).

Parts of CNV regrowth may occur along the vascular empty sleeve, which remain after anti-VEGF treatment.