Synthesis and characterization of a chondroitin sulfate-polyethylene glycol corneal adhesive.

PURPOSE: To describe the synthesis of a chondroitin sulfate-polyethylene glycol (CS-PEG) adhesive and characterize its physical and biological properties in vitro and in vivo. SETTING: Johns Hopkins University and a research facility, Baltimore, Maryland, USA. METHODS: Metabolic activity (WST-1 reagent) was used to evaluate the cytocompatibility of the adhesive with rabbit primary epithelial, stromal, and endothelial cells. Full-thickness corneal incisions (3.0 mm) in ex vivo porcine eyes were sealed with the adhesive, and burst pressure was evaluated to determine the effectiveness of the material in maintaining intraocular pressure (IOP). Finally, a partial-thickness incision was made in a swine cornea and then sealed using the adhesive. Two weeks postoperatively, both eyes were enucleated and examined grossly and histologically. RESULTS: In vitro results showed cytocompatibility of the tissue adhesive with corneal cells and an ability to seal full-thickness corneal incisions exposed to IOPs of 200 mm Hg and higher. Histological evidence from in vivo data confirmed that the CS-PEG material is biodegradable, induces minimal inflammatory response, resists epithelial cell ingrowth, and does not induce scar formation. CONCLUSIONS: The new adhesive was effective in restoring IOP and withstanding pressures greater than 200 mm Hg after being applied to a full-thickness corneal incision. The adhesive material was biocompatible with the 3 types of cells found in corneal tissue. When the adhesive was implanted in a live swine model, no adverse side effects were observed.

Collagen Vitrigel membranes for the in vitro reconstruction of separate corneal epithelial, stromal, and endothelial cell layers.

The goal of this study was to evaluate the potential suitability of collagen Vitrigel (CV) membrane as a substrate for the separate reconstruction of the three main cellular layers of the cornea. Limbal explants, keratocytes, and endothelial cells were cultured on transparent membranes made of type I collagen. The resulting cell sheets were evaluated using RT-PCR, in addition to light and electron microscopy. Tensile testing was also performed to examine the mechanical properties of CV. Limbal explant cultures resulted in partially stratified epithelial sheets with upregulation of the putative stem cell marker p63. Keratocytes cultured in serum on CV exhibited stellate morphology along with a marked increase in expression of corneal crystallin ALDH and keratocan, (a keratan sulphate proteoglycan: KSPG), compared to identical cultures on tissue culture plastic. Endothelial cells formed dense monolayers with uniform cell size, tight intercellular junctions, and expression of voltage-dependent anion channels VDAC2 and VDAC3, chloride channel protein CLCN2, and sodium bicarbonate transporter NBC1. Epithelial and endothelial cells exhibited adhesive structures (desmosomes and hemidesmosomes) and evidence of apical specialization (microplicae), while endothelial cells also produced a Descemet's membrane-like basal lamina. CV was found to possess ultimate tensile strengths of 6.8 +/- 1.5 MPa when hydrated and 28.6 +/- 7.0 MPa when dry. Taken together, these results indicate that CV holds promise as a substrate for corneal reconstruction.