Biodegradable Microsphere-Hydrogel Ocular Drug Delivery System for Controlled and Extended Release of Bioactive Aflibercept In Vitro

Abstract

Purpose: Current standard of care for neovascular eye diseases require repeated intravitreal bolus injections of anti-vascular endothelial growth factors (anti-VEGFs). The purpose of this study was to validate a degradable microsphere-thermoresponsive hydrogel drug delivery system (DDS) capable of releasing bioactive aflibercept in a controlled and extended manner for 6 months. Materials and Methods:The DDS was fabricated by suspending aflibercept-loaded poly(lactic-coglycolic acid) microspheres within a biodegradable poly(ethylene glycol)-co-(Llactic acid) diacrylate/N-isopropylacrylamide (PEG-PLLA-DA/NIPAAm) thermoresponsive hydrogel. Encapsulation efficiency of DDSs and in vitro release profiles were characterized by iodine-125 radiolabeled aflibercept. The degradation of hydrogel was determined by dry weight changes. The cytotoxicity from degraded DDS byproducts was investigated by quantifying cell viability using LIVE/DEAD® assay. In addition, dot blot and enzyme-linked immunosorbent assay were used to determine the bioactivity of released drug. Finally, morphology of microspheres and hydrogel were investigated by cryo-scanning electron microscopy before and after thermal transformation. Results:The microsphere-hydrogel DDS was capable of releasing bioactive aflibercept in a controlled and extended manner for 6 months. The amount and rate of aflibercept release can be controlled by both the cross-linker concentration and microspheres load amount. The initial burst (release within 24 h) was from 37.35 ± 4.92 to 74.56 ± 6.16 μg (2 and 3 mM hydrogel, each loaded with 10 and 20 mg/ml of microspheres, respectively), followed by controlled drug release of 0.07-0.15 μg/day. Higher PEG-PLLA-DA concentration (3 mM) degraded faster than the lower concentration (2 mM). No significant cytotoxicity from degraded DDS byproducts was found for all investigated time points. Bioactivity of released drug was maintained at therapeutic level over entire release period.

PCL microsphere/PEG‐based composite hydrogels for sustained release of methadone hydrochloride

“…Therefore, these carriers can be incorporated in the hydrogel to avoid a burst release of bioactive molecules from hydrogel because the hydrogel provide an extra diffusion barrier for drug release which increases the drug release period. There are many research based on the utilization of composite systems (microparticle embedded hydrogels) for control the drug or growth factor release . Delie and coworkers developed an easily applicable drug delivery system for the prevention of intimal hyperplasia, through a single administration of a cross‐linked hyaluronic acid hydrogel/poly‐lactic‐co‐glycolic acid (PLGA) microparticle formulation loaded with atorvastatin.…”

Use of biomaterials for sustained delivery of anti-VEGF to treat retinal diseases

“…The hydrogel is currently being validated for biocompatibility in in vivo models of choroidal neovascularization. Another strategy attempted was to embed a NP/MP-based delivery system into a hydrogel system [103,104]. By embedding anti-VEGF filled PLGA microspheres in a thermo-responsive PNIPAAm-PEG-diacrylate hydrogel, Osswald et al were able to achieve a sustained release of Ranibizumab (Lucentis™) and Aflibercept (Eylea™) for almost 200 days in vitro [105].…”

Safety and Biocompatibility of Aflibercept-Loaded Microsphere Thermo-Responsive Hydrogel Drug Delivery System in a Nonhuman Primate Model

“…This is consistent with a decrease in stability and release as reported in our previous studies. 23 However, all the detected vitreous aflibercept concentrations were well above the reported IC 50 for human umbilical vein endothelial cells (HUVECs) in vitro (0.003 ng/μL). 29…”

“…The results of the present study using a nonhuman primate model are consistent with our previous studies using aflibercept-DDS in cell-based models and rodents. 18,20,23,30,31 In support of the current study, we have done detailed physicochemical characterization of the DDS formulation in our previous publications. 17,23,24 We have also previously demonstrated in vitro drug release 17,18,20,23,31 and in vivo safety and efficacy of the DDS in a small rodent model.…”

“…18,20,23,30,31 In support of the current study, we have done detailed physicochemical characterization of the DDS formulation in our previous publications. 17,23,24 We have also previously demonstrated in vitro drug release 17,18,20,23,31 and in vivo safety and efficacy of the DDS in a small rodent model. 20,30 Specifically, the aflibercept-DDS and its degraded products showed no toxicity to any cells within the eye consistent with the lack of cytotoxicity observed in HUVECs when the aflibercept-DDS was washed for more than three times, identical to the protocol used in this study.…”