The ‘living’ biological bandage : a compact epithelial cell sheet on a hydrogel bandage for management of corneal epithelial injuries

Abstract

The cornea, being the anterior-most structure of the globe, provides transparency to allow transmission of light onto the retina. Corneal epithelial abrasions or chemical injuries to the cornea results in corneal opacity, hence resulting in vision impairment. Current therapeutic strategies for corneal epithelial defects include topical corticosteroids, lubricants, antibiotics, amniotic membrane transplantation, and corneal grafts. However, these come with potential complications. Here we present a cell sheet transplantation method, constructed using the Aqueous Two-Phase System (ATPS), for management of corneal epithelial injuries. We aim to measure the increase in rate of re-epithelialization of the cornea after transplanting a cell sheet onto the wounded surface, using both in vitro and ex vivo porcine models. We also aim to demonstrate the feasibility of the transplantation process, via a hydrogel bandage as the vehicle of delivery of the cell sheet. A primary human corneal epithelial cell line was used for in vitro and ex vivo experiments. The corneal epithelial cell sheet was constructed using the ATPS which comprised of Poly(ethylene glycol)(PEG)-rich phase and the Dextran(DEX)-rich phase. Characterization of cells, viability tests and optimization of cell sheet construction conditions were performed. An in vitro Transwell study was performed over 7 days to demonstrate the increased rate of re-epithelialisation after cell sheet transplantation for both groups using only cell sheet and cell sheet transplanted with a hydrogel bandage, compared with the control group (p < 0.05). Cytokines GM-CSF, IL-1b, IL-6, IL-8 and TNF-𝛼 concentrations were also shown to be elevated in groups with cell sheet transplanted, compared with control group (p < 0.05). In addition, the ex vivo porcine cornea model demonstrated feasibility of the cell sheet transplantation via a hydrogel bandage, and the adherence and proliferation of the cell sheet on the denuded porcine corneal surface for at least 7 days. Our current results demonstrate the potential for the ATPS-constructed cell sheet to re-epithelialise the cornea, by using a hydrogel bandage as the vehicle of delivery, and act as a therapeutic strategy for corneal epithelial injuries. In the future, experiments conducted on in vivo models are required to demonstrate the efficacy and physiological compatibility of this therapeutic strategy for corneal wound repair.