Biodistribution of Reconstituted High-Density Lipoprotein Nanoparticles for Targeted Delivery to Retinal Ganglion Cells.

Purpose: Nanoparticle-based drug delivery systems offer a promising approach for overcoming the challenges of ocular drug delivery. Our study evaluated the biodistribution and potential targeting of reconstituted high-density lipoprotein nanoparticles (rHDL NPs) loaded with near-infrared dye IR780 to retinal ganglion cells (RGCs) and optic nerve head astrocytes (ONHAs) as a model for neuroprotective drug delivery in glaucoma.

Methods

A stable rHDL-payload complex was formulated using IR780, phosphatidylcholine, and apolipoprotein A-I (Apo A-I) by using a novel preparation method. Fluorescent rHDL (rHDL-IR780) was assessed for cellular uptake in primary human ONHAs in vitro, whereas scavenger receptor class B1 (SR-B1) expression was confirmed by Western blot. Receptor-mediated uptake was examined by SR-B1 receptor blocking. Ex vivo biodistribution was evaluated by intravitreal injection of rHDL into postmortem human donor eyes.

Results

Spectroscopic analysis confirmed IR780 encapsulation in rHDL NPs. Blocking SR-B1 receptors significantly reduced IR780 uptake by ONHAs, supporting an SR-B1-mediated delivery mechanism, in addition to confirming SR-B1 expression in human retinal lysates. In ex vivo experiments, 4 h postinjection, IR780 localized in the retinal nerve fiber and ganglion cell layers. By 24 h, IR780 penetrated deeper retinal layers, achieving RGC uptake.

Conclusions

Our findings demonstrate that rHDL NPs facilitate targeted delivery to retinal tissues through an Apo A-I/SR-B1 pathway, overcoming ocular barriers to reach RGCs. This study supports the potential of rHDL NPs as a platform for neuroprotective drug delivery to treat glaucoma, enhancing both pharmacokinetics and targeted cellular uptake.