Development of gelatin/ascorbic acid cryogels for potential use in corneal stromal tissue engineering

To offer an ideal hospitable environment for corneal keratocyte growth, the carrier materials can be functionalized with incorporation of signaling molecules to regulate cell biological events. This study reports, for the first time, the development of gelatin/ascorbic acid (AA) cryogels for keratocyte carriers in vitro and in vivo. The cryogel samples were fabricated by blending of gelatin with varying amounts of AA (0-300 mg) and carbodiimide cross-linking via cryogelation technique. Hydrophilic AA content in the carriers was found to significantly affect cross-linking degree and pore dimension of cryogels, thereby dictating their mechanical and biological stability and AA release profile. The cryogel carriers with low-to-moderate AA loadings were well tolerated by rabbit keratocyte cultures and anterior segment eye tissues, demonstrating good ocular biocompatibility. Although higher incorporated AA level contributed to enhanced metabolic activity and biosynthetic capacity of keratocytes grown on cryogel matrices, the presence of excessive amounts of AA molecules could lead to toxic effect and limit cell proliferation and matrix production. The cytoprotective activity against oxidative stress was shown to be strongly dependent on AA release, which further determined cell culture performance and tissue reconstruction efficiency. With the optimum AA content in carrier materials, intrastromally implanted cell/cryogel constructs exhibited better capability to enhance tissue matrix regeneration and transparency maintenance as well as to mitigate corneal damage in an alkali bum-induced animal model. It is concluded that understanding of antioxidant molecule-mediated structure-property-function interrelationships in gelatin/AA cryogels is critical to designing carrier materials for potential use in corneal stromal tissue engineering. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.