Multi-layered silk film co-culture system for human corneal epithelial and stromal stem cells

With insufficient options to meet the clinical demand for cornea transplants, one emerging area of emphasis is on cornea tissue engineering. In the present study, the goal was to combine the corneal stroma and epithelium into one co-culture system, in order to monitor both human corneal stromal stem cell (hCSSC) and human corneal epithelial cell (hCE) growth and differentiation into keratocytes and differentiated epithelium in these 3D tissue systems in vitro. Co-culture conditions were first optimized, including the medium, air/liquid interface culture, and surface topography and chemistry of biomaterial scaffold films based on silk protein. The silk was used as scaffolding for both stromal and epithelial tissue layers because it is cell compatible, can be surface patterned, and is optically clear. Next, the effects of proliferating and differentiating hCEs and hCSSCs in this in vitro system were studied, including the effects on cell proliferation, matrix formation by immunochemistry, and gene expression by RT-qPCR. The incorporation of both cell types into the co-culture system demonstrated more complete differentiation and growth for both cell types compared to the corneal stromal cells and corneal epithelial cells alone. Silk films for corneal epithelial culture were optimized to combine a 4.0 micron-scale surface pattern with bulk-loaded collagen type IV. Differentiation of each cell type was in evidence based on increased expression of corneal stroma and epithelial proteins and transcript levels after 6 weeks in co-culture on the optimized silk scaffolds. This article is protected by copyright. All rights reserved.