Intravitreal delivery of VEGF-A₁₆₅-loaded PLGA microparticles reduces retinal vaso-obliteration in an in vivo mouse model of Retinopathy of Prematurity

Abstract

Purpose : Retinopathy of prematurity (ROP) is a disease of abnormal retinal vascularization in preterm infants which can result in negative visual outcomes, including blindness. Vascular endothelial growth factor (VEGF) is a potent angiogenic factor in ROP pathogenesis, and has several isoforms with the pro-angiogenic VEGF-A₁₆₅ predominant in the eye. We hypothesize that intravitreal VEGF-A₁₆₅ in a sustained release vehicle would promote retinal revascularization in an in vivo mouse model of oxygen-induced retinopathy (OIR).

Methods : VEGF-A₁₆₅-loaded poly(lactide-co-glycolide) (PLGA) microparticles were fabricated using a water-in-oil-in-water double emulsion method. 39 neonatal mice were exposed to 77% oxygen from postnatal day 7 (P7) to P12 (OIR mice), and received intra-vitreal injections of VEGF-A₁₆₅-loaded (n=15) or empty (n=14) PLGA microparticles to their right eyes. The left eyes of each mouse were controls. After anesthesia, retinal fluorescein angiography (FA) was performed at P20, and vascular parameters were quantified.

Results : VEGF-A₁₆₅-loaded PLGA microparticles with an average diameter of 4.2 μm were fabricated. VEGF loading level was 8.6 wt%. Retinal avascular area was significantly reduced in VEGF-treated right eyes (VEGF-RE) (39.5±9.0%) compared to eyes treated with empty PLGA microparticles (empty-RE) (52.4±6.7%) or left eye controls (empty-LE (49.5±5.4%), VEGF-LE (52.6 ±6.1%)) (P<0.0001). Retinal vein dilation (P=0.0001) and retinal artery tortuosity (P=0.0007) were reduced in VEGF-treated eyes compared to empty-RE and LE controls.

Conclusions : Our results agree with our hypothesis that intravitreal injection of selective pro-angiogenic VEGF-A₁₆₅ encapsulated in PLGA microparticles, capable of sustained release, in OIR mice reduces ischemia-induced vaso-obliteration and promotes recovery from retinal vein dilation and arterial tortuosity, which may prevent pathologic neovascularization. This technique may alleviate the concerns of the systemic effect of non-selective-VEGF blockade on developing organs in current ROP therapy and the need for multiple treatments due to their short-lived effects. Further studies are needed to optimize the pharmacokinetics, dosage, and efficacy of the VEGF-loaded microparticles.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

FA in OIR Mice Treated with VEGF-loaded and empty microparticles

 

Quantitfication of Vascular Parameters