The repair of tissue damage is a key survival process in all organisms and involves the coordinated activation of several cell types. Cell-cell communication is clearly fundamental to this process, and a great deal is known about extracellular communication within the wound site via cytokines. Here we show that direct cell-cell communication through connexin 43 (Cx43) gap junction channels also plays a major role in the wound healing process. In two different wound healing models, incisional and excisional skin lesions, we show that a single topical application of Cx43 antisense gel brings about a transient downregulation of Cx43 protein levels, and this results in a dramatic increase in the rate of wound closure. Cx43 knockdown reduces inflammation, seen both macroscopically, as a reduction in swelling, redness, and wound gape, and microscopically, as a significant decrease in neutrophil numbers in the tissue around the wound. One long-term consequence of the improved rate of healing is a significant reduction in the extent of granulation tissue deposition and the subsequent formation of a smaller, less distorted, scar. This approach is likely to have widespread therapeutic applications in other injured tissues and opens up new avenues of research into improving the wound healing process.

Wound healing is a complex process requiring communication for the precise co-ordination of different cell types. The role of extracellular communication through growth factors in the wound healing process has been extensively documented, but the role of direct intercellular communication via gap junctions has scarcely been investigated. We have examined the dynamics of gap junction protein (Connexins 26, 30, 31.1 and 43) expression in the murine epidermis and dermis during wound healing, and we show that connexin expression is extremely plastic between 6 hours and 12 days post-wounding. The immediate response (6 h) to wounding is to downregulate all connexins in the epidermis, but thereafter the expression profile of each connexin changes dramatically. Here, we correlate the changing patterns of connexin expression with key events in the wound healing process.

Transforming growth factor (TGF)-beta regulates wound repair and scarring in an isoform-specific fashion. TGF-beta is produced in a latent form, and its activation is a critical regulatory step controlling the bioactivity of this growth factor. To date, it has been impossible to determine latent TGF-beta activation in vivo due to a lack of quantitative assays. We describe here a semiquantitative modification of the plasminogen activator inhibitor-1/luciferase bioassay (PAI/L assay) for TGF-beta, which we used to determine active and latent TGF-beta isoforms in frozen sections of rat wound tissue. We found that significant amounts of latent TGF-beta were rapidly activated upon wounding (38% of the total TGF-beta at 1 hour after wounding). A second peak of active TGF-beta (17% of total) occurred at 5 days after wounding. The predominant isoforms were TGF-beta1 and -2 with only minor amounts of TGF-beta3 present. This is the first TGF-beta bioassay allowing semiquantitative determination of active and latent isoforms present in vivo, and our results document the significance and temporal regulation of latent TGF-beta isoform activation in wound repair.

No abstract

No abstract