Evaluation of polyesteramide (PEA) and polyester (PLGA) microspheres as intravitreal drug delivery systems in albino rats.
PURPOSE
To study the suitability of injectable microspheres based on poly(ester amide) (PEA) or poly lactic-co-glycolic acid (PLGA) as potential vehicles for intravitreal drug delivery in rat eyes. Dexamethasone-loaded PEA microspheres (PEA + DEX) were also evaluated.


METHODS
Forty male Sprague Dawley rats were divided into four groups that received different intravitreally injected microspheres: PEA group (n = 12); PLGA group (n = 12); PEA + DEX group (n = 8); and control group (no injection, n = 8). Electroretinography (ERG), fundus autofluorescence (FAF), and spectral domain optical coherence tomography (sdOCT) were performed at baseline, weeks 1 and 2, and months 1, 2, and 3 after intravitreal injection. Eyes were histologically examined using light microscopy and transmission electron microscopy at the end of the in vivo study.


RESULTS
There were no statistically significant changes in ERG among the groups. Abnormal FAF pattern and abnormal deposits in OCT were observed after injection but almost completely disappeared between week 2 and month 3 in all injected groups. GFAP staining showed that Müller glia cell activation was most pronounced in PLGA-injected eyes. Increased cell death was not observed by TUNEL staining at month 1. In electron microscopy at month 3, the remnants of microparticles were found in the retinal cells of all injected groups, and loss of plasma membrane was seen in the PLGA group.


CONCLUSIONS
Although morphological changes such as mild glial activation and material remnants were observed histologically 1 month and 3 months after injection in all injected groups, minor cell damage was noted only in the PLGA group at 3 months after injection. No evidence of functional abnormality relative to untreated eyes could be detected by ERG 3 months after injection in all groups. Changes observed in in vivo imaging such as OCT and FAF disappeared after 3 months in almost all cases.
['Peters|Tobias|T|', 'Kim|Seong-Woo|SW|', 'Castro|Vinicius|V|', 'Stingl|Krunoslav|K|', 'Strasser|Torsten|T|', 'Bolz|Sylvia|S|', 'Schraermeyer|Ulrich|U|', 'Mihov|George|G|', 'Zong|MengMeng|M|', 'Andres-Guerrero|Vanessa|V|', 'Herrero Vanrell|Rocio|R|', 'Dias|Aylvin A|AA|', 'Cameron|Neil R|NR|', 'Zrenner|Eberhart|E|']
D016115:Albinism, Oculocutaneous D000577:Amides D000818:Animals D002214:Capsules D003907:Dexamethasone D004058:Diffusion D058449:Intravitreal Injections D019344:Lactic Acid D008297:Male D008422:Materials Testing D008863:Microspheres D011091:Polyesters D011100:Polyglycolic Acid D000077182:Polylactic Acid-Polyglycolic Acid Copolymer D051381:Rats D017207:Rats, Sprague-Dawley D012160:Retina
Poly lactic-co-glycolic acid (PLGA) Transmission electron microscopy TUNEL stain Aliphatic dicarboxylic acids and aliphatic α-ω diols (PEA) Fundus auto-fluorescence Immunohistochemistry Invivo electroretinography Invivo optical coherence tomography Poly ester amide based on α-amino acids