Abstract
Purpose :
The inner limiting membrane (ILM) represents a major bottleneck for the retinal delivery of therapeutics following intravitreal (IVT) injection. Overcoming the ILM barrier could hence signify a great leap forward for many retinal therapies in the pipeline. Making use of the clinically approved dye indocyanine green (ICG) and pulsed laser light, we aim to photoporate the ILM in a safe way, allowing therapeutics to enter the retina in a highly efficient manner. Following up on our proof-of-concept study in bovine explants, this in vivo study further explores the safety and efficacy of ICG-mediated ILM photodisruption.
Methods :
3 New Zealand white rabbits (6 eyes, age 3-6 months) received ILM photodisruption treatment. First, 40 μl of 0.625 mg/mL ICG solution was injected into the vitreous close to the retina to maximize ICG binding to the ILM. To allow unbound ICG to be cleared, laser treatment was performed 4 days following ICG injection. To this end, anesthetized rabbits were placed on a stabilization platform after which a 5 by 5 mm2 area per eye was irradiated with laser pulses (<7 ns, 800 nm) at a fluence of 1.9 J/cm2. After an AAV9 injection (1x1012 vg/mL) on the same day, animals were monitored for 4 weeks with PAM, OCT, color fundus photography, fluorescence imaging (FI) and ERG. 1 rabbit which received an AAV9 injection without ILM photodisruption treatment served as a control.
Results :
Based on the FI imaging, we demonstrated that for all 6 eyes AAV9 transduction in the laser-treated area was substantially higher. Fluorescence intensity measurements of the treated area revealed a 2.4 fold increase at day 7 as compared to the control animal, a trend which persisted for the next 3 weeks. OCT, dark-adapted and light-adapted ERG did not reveal any effect on retinal morphology or function, respectively.
Conclusions :
This study demonstrates that ICG-mediated ILM photoporation is a safe method to overcome the ILM and enhance retinal therapeutic delivery. This technology is able to greatly promote the delivery and hence transduction potency of viral vectors into the retina following IVT injection. Driven by this positive outcome, future plans include exploration of its potential for other therapeutic classes including nanoparticles and cells.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.