Stereolithography 3D Bioprinting Method for Fabrication of Human Corneal Stroma Equivalent

3D bioprinting technology is a promising approach for corneal stromal tissue regeneration. In this study, gelatin methacrylate (GelMA) mixed with corneal stromal cells was used as a bioink. The visible light-based stereolithography (SLA) 3D bioprinting method was utilized to print the anatomically similar dome-shaped structure of the human corneal stroma. Two different concentrations of GelMA macromer (7.5 and 12.5%) were tested for corneal stroma bioprinting. Due to high macromer concentrations, 12.5% GelMA was stiffer than 7.5% GelMA, which made it easier to handle. In terms of water content and optical transmittance of the bioprinted scaffolds, we observed that scaffold with 12.5% GelMA concentration was closer to the native corneal stroma tissue. Subsequently, cell proliferation, gene and protein expression of human corneal stromal cells encapsulated in the bioprinted scaffolds were investigated. Cytocompatibility in 12.5% GelMA scaffolds was observed to be 81.86 and 156.11% at day 1 and 7, respectively, which were significantly higher than those in 7.5% GelMA scaffolds. Elongated corneal stromal cells were observed in 12.5% GelMA samples after 7 days, indicating the cell attachment, growth, and integration within the scaffold. The gene expression of collagen type I, lumican and keratan sulfate increased over time for the cells cultured in 12.5% GelMA scaffolds as compared to those cultured on the plastic tissue culture plate. The expression of collagen type I and lumican were also visualized using immunohistochemistry after 28 days. These findings imply that the SLA 3D bioprinting method with GelMA hydrogel bioinks is a promising approach for corneal stroma tissue biofabrication.