Abstract
Purpose :
A clinical need exists for more effective therapeutics and sustained drug delivery systems to promote ocular surface healing. This study tested the hypothesis that a novel biodegradable, thermoresponsive hydrogel loaded with the human recombinant (rh)MG53 protein, which we have demonstrated promotes corneal healing without fibrosis, would exhibit safety and biocompatibility in vitro and in vivo.
Methods :
Hydrogel optimization was done based on varying concentrations of poloxamer 407, poloxamer 188, and hydroxypropyl methylcellulose using a 32 factorial design. In situ forming gels were prepared by mixing components at 4°C prior to gelation at physiologic temperatures. Hydrogel viscoelasticity and gelation temperature were characterized using frequency and temperature sweep tests on a rheometer. Up to 1 mg/mL rhMG53 was loaded into the hydrogels and allowed to gel at 37°C. Release studies were performed by adding preheated artificial tear solution (ATS) to the hydrogel and further incubating for up to 24 hours; at different time intervals, ATS was withdrawn and replaced with fresh ATS. The rhMG53 release profile in the collected ATS was acquired using an ELISA. Using lactate dehydrogenase and water-soluble tetrazolium salt-1 assays, potential hydrogel toxicity was evaluated in vitro in cultured corneal epithelium, fibroblasts, and endothelium. In vivo safety and tolerability was assessed in mice; hydrogel was applied topically twice daily for up to 14 days. Sample size=5; significance was set at P<0.05.
Results :
The optimized hydrogel formulations had a gelation temperature of 27-33°C. A burst release of rhMG53 (70.7±19.4ug/mL) was noted within the first 30 minutes, exceeding minimum dosing of 10ug/mL, and was continuously released for 24 hours (cumulative release=45.4%). No significant changes in cell density or viability were noted in any cultured cells. Clinically, no changes in the murine ocular surface were noted following repeated hydrogel application. As assessed via histology, the hydrogel did not result in any detrimental changes to the globe or adnexa.
Conclusions :
Our poloxamer-based thermoresponsive hydrogel effectively released rhMG53 protein at levels previously shown effective at promoting corneal healing, was not cytotoxic, and was well-tolerated in vivo with repeated application.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.