Abstract
Purpose :
Systemic therapies targeted to choroidal neovascular lesions and affected cells can open new avenues for treating back of the eye disorders. We evaluated the ability of hydroxyl dendrimers labelled with indocyanine green (ICG) to target choroidal neovascular (CNV) lesions, and further into macrophages and the retinal pigment epithelium, after systemic administration in a mouse model of laser-induced CNV.
Methods :
Hydroxyl dendrimers (~14000 Da, 4 nm) were covalently conjugated to 2-3 ICG molecules (D-ICG) per dendrimer. Two studies were conducted in C57BL/6 mice (n=5/group) administered IV 100 µL of D-ICG or vehicle control. In the first study, mice were administered D-ICG at 1, 3, 7, or 14 days post-laser and eyes were analyzed by optical coherence tomography (OCT) with ICG imaging at 4 or 24 hr post-dose. The second study evaluated the persistence of D-ICG in the CNV lesion after a single dose of D-ICG 24 hr post-laser. Cellular localization was evaluated by administration of the hydroxyl dendrimer labelled with tetramethylrhodamine (D-TRITC, IV, 100 µL, 1 hr after D-ICG dose). In both studies, flat-mounts of the sclera-choroid/retinal pigment epithelial (RPE) complexes were stained by fluorescently tagged isolectin and IBA-1 in the first study and IBA-1 alone in the second study.
Results :
Systemically administered D-ICG was selectively taken up by cells within the CNV lesions within 24 hr after dosing, whereas the free ICG distributes non-specifically and is typically cleared within hours. IBA-1 signal increased up to 24-48 hr after laser injury. A single systemic D-ICG dose given 24 hr after laser injury localized to the CNV lesion and significant D-ICG was still present at the last time point (28 days; Figure below). D-ICG and D-TRITC appeared to be intracellular and focused in regions of IBA-1 signal consistent with previous studies demonstrating hydroxyl dendrimer uptake in reactive microglia, macrophage and RPE cells.
Conclusions :
Hydroxyl dendrimers (D-ICG) target to CNV lesions after systemic administration and persist for at least 28 days post-dose, with significant implications for sustained, targeted therapies. Previous studies have shown hydroxyl dendrimers are systemically cleared within 24 hr in mice and humans.
This is a 2020 ARVO Annual Meeting abstract.