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Recurrent corneal erosion (RCE) is a condition where the superficial corneal epithelial cells sporadically shed because of poor attachment to the underlying basement membrane, resulting in pain and discomfort. RCE-afflicted corneas exhibit elevated biological factors and enzymes, such as matrix metalloproteinase (MMP)-9. Soft bandage contact lenses (BCLs) are a commonly recommended treatment as they permit continued vision during recovery. However, they do not outperform alternative treatments as they currently lack active ingredients for ocular surface repair. Development of BCLs with a sustained release of active ingredients to promote RCE wound healing over an extended period of time would be clinically valuable. We fabricated gelatin methacrylate (GelMA) hydrogels with MMP-9-triggered controlled release for further BCL development. GelMA disks were characterized to determine the optimal concentration and methacrylation degree for sustained release in the presence of MMP-9. The chosen active ingredient, 60 kDa hyaluronic acid (HA), was verified to promote wound healing in rabbit corneal epithelial cell and human corneal epithelial cell wound assays. The active ingredient was loaded into GelMA hydrogels, and the bioavailability of the vehicle was determined. The GelMA hydrogels revealed a tunable profile for diffusion and enzyme-mediated controlled release of a model molecule. The 60 kDa HA-loaded GelMA disks showed improvement in wound healing at HA loadings of 150 and 250 μg by improving the wound healing rates by 28% (68.7% wound closure) and 26% (67.9% wound closure), respectively, compared to the control (50.5% wound closure) at 24 h. The HA-loaded GelMA disks with 150 and 250 μg HA also exhibited shortened wound closure time of 75 h compared to >147 h with a bolus daily delivery of HA for wound closure. Overall, we demonstrated that the fabricated GelMA hydrogels offered an enzyme-triggered option as a sustained release material for future RCE treatments.

Cardiovascular diseases remain the leading cause of death worldwide. Patency rates of clinically-utilized small diameter synthetic vascular grafts such as Dacron® and expanded polytetrafluoroethylene (ePTFE) to treat cardiovascular disease are inadequate due to lack of endothelialization. Sodium trimetaphosphate (STMP) crosslinked PVA could be potentially employed as blood-compatible small diameter vascular graft for the treatment of cardiovascular disease. However, PVA severely lacks cell adhesion properties, and the efforts to endothelialize STMP-PVA have been insufficient to produce a functioning endothelium. To this end, we developed a one-pot method to conjugate cell-adhesive protein via hydroxyl-to-amine coupling using carbonyldiimidazole by targeting residual hydroxyl groups on crosslinked STMP-PVA hydrogel. Primary human umbilical vascular endothelial cells (HUVECs) demonstrated significantly improved cells adhesion, viability and spreading on modified PVA. Cells formed a confluent endothelial monolayer, and expressed vinculin focal adhesions, cell-cell junction protein zonula occludens 1 (ZO1), and vascular endothelial cadherin (VE-Cadherin). Extensive characterization of the blood-compatibility was performed on modified PVA hydrogel by examining platelet activation, platelet microparticle formation, platelet CD61 and CD62P expression, and thrombin generation, which showed that the modified PVA was blood-compatible. Additionally, grafts were tested under whole, flowing blood without any anticoagulants in a non-human primate, arteriovenous shunt model. No differences were seen in platelet or fibrin accumulation between the modified-PVA, unmodified PVA or clinical, ePTFE controls. This study presents a significant step in the modification of PVA for the development of next generation in situ endothelialized synthetic vascular grafts.