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.