Galectins-3 and -7, but not Galectin-1, Play a Role in Re-epithelialization of Wounds

Disorders of wound healing characterized by impaired or delayed re-epithelialization are a serious medical problem. These conditions affect many tissues, are painful, and are difficult to treat. In this study, using cornea as a model, we demonstrate for the first time the importance of carbohydrate-binding proteins galectins-3 and -7 in re-epithelialization of wounds. In two different models of corneal wound healing, re-epithelialization of wounds was significantly slower in galectin-3-deficient (gal3 −/− ) mice compared with wild-type (gal3 +/+ ) mice. In contrast, there was no difference in corneal epithelial wound closure rates between galectin-1-deficient and wild-type mice. Quantitation of the bromodeoxyuridine-labeled cells in gal3 +/+ and gal3 −/− corneas revealed that corneal epithelial cell proliferation rate is not perturbed in gal3 −/− corneas. Exogenous galectin-3 accelerated re-epithelialization of wounds in gal3 +/+ mice but, surprisingly, not in the gal3 −/− mice. Gene expression analysis using cDNA microarrays revealed that healing corneas of gal3 −/− mice contain markedly reduced levels of galectin-7 compared with those of gal3 +/+ mice. More importantly, unlike galectin-3, galectin-7 accelerated re-epithelialization of wounds in both gal3 −/− and gal3 +/+ mice. In corresponding experiments, recombinant galectin-1 did not stimulate the corneal epithelial wound closure rate. The extent of acceleration of re-epithelialization of wounds with both galectin-3 and galectin-7 was greater than that observed in most of the published studies using growth factors. These findings have broad implications for developing novel therapeutic strategies for treating nonhealing wounds.