Effect of liposome encapsulation on diffusion kinetics of ripasudil in the polarized retinal pigment epithelial cells

Abstract

Purpose : We previously reported liposome-encapsulate-ripasudil (Lipo-Ripa) could suppress proliferative vitreoretinopathy progression more efficiently by its prolonged residency in the vitreous compared to ripasudil (Ripa) in a rabbit model (Ji et al ARVO 2021). The purpose of this study was to investigate the permeability of Lipo-Ripa in polarized retinal pigment epithelial (RPE) layer in vitro.

Methods : Human fetal RPE cells were seeded onto fibronectin-coated transwell inserts and cultured in RPE cell growth medium for more than 2 weeks to establish polarized RPE monolayer. To examine the permeability of Ripa and Lipo-Ripa passing through the RPE layer, the drugs diluted by oxiglutatione ocular irrigating solution (BSS) were added to the inserts separately, and BSS were also added to the lower chamber. The medium in the lower chamber was collected at different timepoints and the concentration of Ripa was measured by LC-MS/MS. The permeation ratio of the Ripa was calculated by the following formula: Permeation (%) = amount of Ripa in the lower chamber/ initial amount of total Ripa. The ability to bind to the RPE cells of liposome was also examined using FITC-labeled liposomes.

Results : After 48 hours, the average permeation of Ripa was 48%, while that of Lipo-Ripa was 5%. The permeation of Lipo-Ripa group was significantly lower than Ripa-group within 48h (P < 0.001). The higher FITC-signal could be found within and around the RPE cells after treatment with FITC-labeled liposomes but not with FITC solution.

Conclusions : Liposome encapsulation enhances less permeability of RPE layer by higher affinity to RPE cells, which may contribute to prolonged residency of Lipo-Ripa in the vitreous cavity in vivo.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.