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An ex vivo assay to measure the intravitreal mobility of nanomedicines for retinal gene therapy
Author(s) -
MARTENS TF,
VERCAUTEREN D,
FORIER K,
DESCHOUT H,
REMAUT K,
DEMEESTER J,
DE SMEDT SC,
BRAECKMANS K
Publication year - 2012
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2012.4261.x
Subject(s) - gene delivery , ex vivo , peg ratio , drug delivery , materials science , polystyrene , cationic polymerization , surface modification , polymer , nanoparticle , biomedical engineering , chemistry , biophysics , nanotechnology , transfection , biochemistry , polymer chemistry , organic chemistry , medicine , in vitro , gene , finance , biology , economics
Purpose In retinal gene therapy, intravitreal injection is a promising technique for administering nanomedicines, granted they remain mobile in the vitreous humour. Here, we optimized an ex vivo assay to measure this mobility in intact bovine vitreous. The results from this work and the newly developed methodology are expected to aid in the rational design of nanomedicines for retinal drug delivery. Methods Excised bovine eyes were prepared in such a way to preserve the fragile structure of the vitreous humour, while permitting fluorescence microscopy inside the bovine vitreous. This assay was used to determine by single particle tracking analysis the intravitreal mobility of both model polystyrene beads with different sizes and surface groups, as well as gene nanomedicines composed of poly(amido amine)s and plasmid DNA. Results Cationic nanoparticles were readily immobilized in the vitreous humour, while anionic polystyrene beads remained mobile. Surface modification with the hydrophilic polymer polyethylene glycol (PEG) resulted in the best mobility of the polystyrene beads. In correspondence with these results, the cationic gene nanomedicines were immobilized in the vitreous humour, while modification with PEG resulted in a drastic improvement of their mobility. Conclusion Here an ex vivo assay is presented to study nanoparticle mobility in intact vitreous humour by single particle tracking microscopy, which showed that cationic surface charge limits intravitreal diffusion of nanoparticles by binding to biopolymer structures, while anionic and PEGylated nanoparticles remain mobile. These results should help in the rational design of nanomedicines used for intravitreal drug delivery.