Sustaining Intravitreal Residence With L-Arginine Peptide-Conjugated Nanocarriers

Abstract

PurposeIntravitreal injection of antiangiogenic agents is becoming a standard treatment for neovascular retinal diseases. Sustained release of therapeutics by injecting colloidal carriers is a promising approach to reduce the injection frequency, which reduces treatment burdens and the risk of complications on patients. Such sustained release often requires carriers to have micrometer-scale dimension that, however, can potentially promote glaucoma and inflammation. Small, polycationic particles can be immobilized in vitreous through multiple cooperative ionic interactions with hyaluronic acid of the vitreous interior, but such particles are generally toxic. Here, we synthesized and examined a biocompatible dextran-based nanocarrier (<50 nm in diameter) conjugated with cationic peptides containing L-arginine with minimal toxicity, aiming to provide sustained release of therapeutic drugs in vitreous.MethodsWe synthesized the nanocarriers with condensed cholesteryl dextran (CDEX) as core material. Cationic peptides containing 1 to 4 arginine groups, along with fluorescence tags, were conjugated to the CDEX surface. We monitored the carrier diffusion rate ex vivo and half-lives in vivo in rodent vitreous using fluorescence imaging. We evaluated the toxicity by histological examinations at the second, third, eighth, and thirty-sixth week.ResultsThe diffusion rate of nanocarriers was inversely related to zeta potential values in freshly isolated vitreous humor. We observed increased half-lives in vivo with increasing zeta potential (up to 240 days). Histological examinations confirmed no adverse effects on ocular morphology and organization.ConclusionsWe demonstrated the potential of L-arginine peptide-conjugated nanocarriers toward safe and sustained therapeutic release system for posterior eye diseases.

Extended Intravitreal Rabbit Eye Residence of Nanoparticles Conjugated With Cationic Arginine Peptides for Intraocular Drug Delivery: In Vivo Imaging

“…Peptides with 2, 3, or 4 R per peptide, as their only charged groups , had increased zeta potential, which inversely affected NPC diffusion. 17 Here we focus on 2R and 3R anchor peptide amides, each with just five total amino acids, duplicating natural sequences to minimize immunogenicity. For 2R and 3R peptides, we respectively used the natural sequences: YRVRS-amide from pigment epithelium–derived factor (PEDF, residues 66–70), 19 and RRYRL-amide, a sequence conserved in both Hsp 20 and in A-type α-Crystallin (residues 121–125) 20 ; these proteins are all intraocular.…”

“…CDEX was prepared from 70 kDa Dextran (Dex-70), essentially as described by Li et al 17 Briefly, the condensed nanocarrier was formed by reaction of 4 g Dex-70 with 4 mol % cholesterol, (based on 365 glycosyl monomers per 70 kDa, 4 g = 21 mmol), attached to polymer hydroxyl groups. Dextran was first dried by twice repeated rotary evaporation from anhydrous pyridine, then high vacuum over P 2 O 5 .…”

“…Cholesteryl chloroformate (0.4 g, 0.88 mmol) and one equivalent of triethylamine (TEA) in anhydrous dimethyl sulfoxide (DMSO) formed CDEX. 17 Exhaustively dialyzed product was sonicated to maximize internalization of hydrophobic groups. Cloudy CDEX solution was sequentially filtered through filter paper, then through syringe filters of 0.80 μm, 0.45 μm and 0.20 μm pore size, final filtrate lyophilized.…”

“…1,1′-Carbonyldiimidazole, previously used 17 for CDEX-OH group activation, cannot be sensitively quantified to confirm complete discharge upon reaction with amines. Improved activation here with p -nitrophenylchloroformate ( p -nPCOCl) formed a mixed carbonate between sugar OH groups and p -nitrophenol ( p -nP).…”

“…We recently described a NP system based on condensed dextran (CDEX) for extended IVT drug delivery, where small PEG peptides, having 1 to 4 l -Arg per peptide, were stably conjugated to carrier OH groups. Higher Arg per peptide increased NPC zeta-potential, 17 with concomitant slowing of vitreal diffusion, as monitored by rhodamine tag. NPC (approx.…”