The feasibility study of an in situ marine polysaccharide-based hydrogel as the vitreous substitute.

Although various biopolymers and synthetic compounds have been proposed and tested as the vitreous substitutes, no ideal material has been identified yet. In the present study, we developed an in situ-formed hydrogel by crosslinking hydroxypropyl chitosan with alginate dialdehyde. Physical properties of the hydrogel were studied and the cytotoxicity was evaluated using L929 fibroblasts, rabbit corneal endothelial cells and retinal pigment epithelial cells. In a preliminary in vivo study, the hydrogel was employed as vitreous substitute after vitrectomy surgery on rabbits and multiple parameters indicating biosafety and biocompatibility were measured and analyzed postoperatively. Our results showed that the refractive index, transmittance, pH value and density of the hydrogel were similar to those of human vitreous. Cytotoxicity tests demonstrated the hydrogel to be nontoxic to all of the three cell lines selected. Using the rabbit model, we showed that the hydrogel could form in situ and postoperative analysis of slit-lamp observation, intraocular pressure, corneal endothelium examination, B-scan ultrasound and fundus photography showed no significant adverse reactions in the operated eyes during the 90-day follow-up. However, electroretinogram and histopathological examinations indicated minor vision decline and decrease of the densities of cones and rods in the operated rabbit eyes. Collectively, our study suggested that the in situ-formed hydrogel could potentially be used as a vitreous substitute, with its long-term safety and efficacy to be further assessed. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1997-2006, 2018.