Honokiol-Loaded Methoxy Poly (Ethylene Glycol) Polycaprolactone Micelles for the Treatment of Age-Related Macular Degeneration

Age-related macular degeneration (AMD), a multifactorial age-related retinal hypoxic disorder resulting in irreversible loss of vision, is the foremost cause of blindness in the United States. Current treatment strategies involve multiple intraocular injections of antivascular endothelial growth factor (VEGF) agents into the vitreous of eye. In addition to the challenges of drug localization and targeted delivery, the need of frequent injections into the eye raises patient compliance issues, and thus call for development of sustained drug delivery systems. In this study, a sustained drug delivery system was prepared by loading an antihypoxia-induced factor (HIF) agent, honokiol (HON), into methoxy poly (ethylene glycol) polycaprolactone (MPEG-PCL) polymer. These HON-MPEG-PCL micelles were characterized by evaluating size, ζ potential, in vitro drug release profile, and morphology by transmission electron microscopy. The cytotoxic nature of developed micelles was assessed on human retinal pigment epithelial cell line (ARPE-19) cells by cytotoxicity assay. The cellular uptake and HIF and VEGF expression levels were determined in in vitro settings. Micelles formed had a particle size of 30.8 ± 0.8 nm with the poly dispersity index of 0.19 ± 0.0004 and ζ potential was found to be -5.46 ± 0.49 mv. Entrapment efficiency was calculated to be 64 ± 0.135%. In vitro drug release showed sustained release of drug from the formulation. Result from in vitro cytotoxicity study confirmed noncytotoxic nature of HON-MPEG-PCL micelles compared to HON drug solution. Furthermore, enzyme-linked immunosorbent assay studies performed showed the periodic downregulation of HIF and VEGF, which are major growth factors involved in underlying mechanism of AMD. The results showed successful development of HON-MPEG-PCL micelles, which may be useful for the effective treatment of AMD.