AAV-mediated anti-VEGF therapeutics increase corneal allograft survival-rate in a model of high-risk corneal transplantation

Abstract

Purpose : Previous studies have shown that pharmacological blockade of vascular endothelial growth factor (VEGF) or VEGF-Receptors (VEGF-Rs) can ameliorate corneal neovascularization and improve allograft survival rates in high-risk keratoplasties. However, repeated injections are required because rejection can occur even years after transplantation. In this study, we aim to determine if a single dose of AAV-mediated anti-VEGF treatment can increase the survival rate of corneal grafts in a model of high-risk keratoplasty.

Methods : The corneal suture paradigm was used to produce a rat model of high-risk keratoplasty. Sutures were placed 14-days prior to keratoplasty. At 5 days prior to keratoplasty, sutures were removed and either an anti-VEGF AAV (5 x 10⁹ genome copies/12μl) or PBS (12μl) was introduced to the cornea via intrastromal injection. CoNV and corneal opacity were assessed post-operatively using slit-lamp microscopy weekly and graft thickness was measured post-operatively using optical coherence tomography (OCT). Corneal graft rejection was defined as moderate stromal opacity with only the pupil margin visible and neovascularization around the peripheral graft. Additionally, intraocular pressure (IOP), as one of ocular safety indicators, was measured once a week. Potential inflammation induced by intrastromal injection of AAV-antiVEGF was also analyzed by measuring the percentage of F4/80+ and CD11b+ cells in the cornea.

Results : We observed a significant reduction in CoNV, corneal opacity, and to a lesser extent, corneal thickness in AAV-treated rats (N=6) compared with the control group (N=6). The survival-rate of the allograft was increased in AAV-anti-VEGF treated animals and the incidence of corneal graft rejection was decreased. IOP remained normal in both groups and no inflammation was noted at 2 weeks post-intrastromal injection at this dosage of AAV (5x 10⁹ genome copies), indicating the treatment of AAV vectored anti-VEGF does not elicit IOP change and inflammation.

Conclusions : Anti-VEGF molecules delivered by AAV vectors are safe and efficacious for the long-term inhibition of corneal neovascularization which increases the survival rate of corneal allografts in high-risk keratoplasty.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.