Alterations in connexin expression and cell communication in healing corneal epithelium

The aim of this study was to examine cell-to-cell metabolite transfer and connexin distribution in the rabbit corneal epithelium, in the stationary state, and during wound healing.

Rabbit corneas were wounded with a surgical tool, producing a 3-mm-wide elongated debridement. Corneas were allowed to heal in vivo for up to 45 hours. Monoclonal antibodies against connexins Cx 26, Cx 32, Cx 43, and Cx 50 were used to stain cryostat sections. Cell-to-cell metabolite transfer capacity was assessed by a modification of the scrape-loading technique using lucifer yellow as the organic ion tracer.

The rabbit corneal epithelium contains Cx 43 and Cx 50, localized in the cell's plasma membrane, as shown previously for other species. Cx 26 and Cx 32 are not detectable. Tracer transfer occurred in both basal and suprabasal cell layers. After wounding, the migrating epithelial monolayer lacked Cx 43 and Cx 50. This change was apparent 6 hours after injury and persisted until complete wound closure (approximately 24 hours). The Cx 50 membrane stain was increased elsewhere, in particular in the transition zone between monolayered and multilayered epithelium. Consistent with the expression changes, migrating cells displayed no or minimal cell-to-cell tracer transfer, whereas in the periphery of the wound, tracer transfer was enhanced in comparison to the control specimen.

Corneal epithelial healing involves biphasic changes in the expression of connexins and cell-to-cell communications. These alterations may be critical for the optimization of the healing response.