Abstract
Corneal blindness is the fourth leading cause of visual impairment. Of specific interest is blindness due to a dysfunctional corneal endothelium which can only be treated by transplanting healthy tissue from a deceased donor. Unfortunately, corneal supply does not meet the demand with only one donor for every 70 patients. Therefore, there is a huge interest in tissue engineering of grafts consisting of an ultra-thin scaffold seeded with cultured endothelial cells. The present research describes the fabrication of such artificial Descemet membranes based on the combination of a biodegradable amorphous polyester (poly (d,l-lactic acid)) and crosslinkable gelatins. Four different crosslinkable gelatin derivatives are compared in terms of processing, membrane quality, and function, as well as biological performance in the presence of corneal endothelial cells. The membranes are fabricated through multi-step spincoating, including a sacrificial layer to allow for straightforward membrane detachment after production. As a consequence, ultrathin (<1µm), highly transparent (>90%), semi-permeable membranes could be obtained with high biological potential. The membranes supported the characteristic morphology and correct phenotype of corneal endothelial cells while exhibiting similar proliferation rates as the positive control. As a consequence, the proposed membranes prove to be a promising synthetic alternative to donor tissue.
Highlights
The cornea is the clear membrane that provides the eye a window to the exterior world
Dimethyl sulfoxide (DMSO) was removed by dialysis (MWCO 12 000–14 000 g mol−1) at 40 °C during 24 h in distilled water followed by freezing and lyophilization. 1H-NMR spectroscopy in deuterium oxide was performed at 40 °C to determine the degree of substitution according to a previously reported protocol.[21]
The carboxylic acid functionalities in 5-norbornene-2-carboxylic acid were converted into an activated succinimidyl ester via reaction with EDC and NHS during 25 h, using a 1.25 times excess of 5-norbornene-2-carboxylic acid to prevent the presence of unreacted EDC molecules which can on the one hand result in the formation of zero-length crosslinks between the primary amines and the carboxylic acids present in gelatin.[22]
Summary
The cornea is the clear membrane that provides the eye a window to the exterior world. Kinoshita et al have treated the very first patients with an injection of a corneal endothelial cell suspension and reported good visual recovery up to 2 years later.[9] currently, the most investigated strategy is to create composite grafts of cells seeded onto a scaffold enabling transplantation similar to the currently applied corneal endothelial grafts Such cell carriers, must exhibit very specific properties, such as transparency, glucose permeability, cytocompatibility, and above all, they must maintain the correct endothelial cell phenotype.[10] To date, attempts have been made to find an ideal corneal endothelial scaffold, which range from biological and biosynthetic to fully synthetic membranes. An underlying PDLLA polyester base should provide the transplant with mechanical strength, thereby enabling corneal endothelial transplantation
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