Abstract
Purpose: :
Poor healing of epithelial wounds in cornea is a major clinical problem, leading to persistent epithelial defects and ulceration. The primary cause is poor cell migration over the wound. Migration involves complex interactions between migrating cells and the extracellular matrix (ECM). Carbohydrate-binding protein galectin-3 (Gal-3) binds to ECMs such as laminin and collagen and promotes lamellipodia formation by cross-linking to α3 integrin. Recombinant Gal-3 also facilitated wound healing in rodent cornea. Wound healing vanished in Gal-3-/- mice because intracellular Gal-3 stimulates production of receptors for Gal-3 that are necessary for cell migration. The purpose of the present experiment was to study Gal-3 in cultured corneal explants from monkey, a model more relevant to man.
Methods: :
n-Heptanol was used to remove the epithelium (7.5 mm diameter) from the central cornea of enucleated monkey eyes. The corneas were then excised, incubated with or without recombinant Gal-3, and stained with 1 % sodium fluorescein. Corneal wound healing was quantified by digital image analysis. Gal-3 in eye tissues was determined by immunoblotting.
Results: :
Relatively high levels of Gal-3 were detected in corneal epithelium. Tear fluid contained minimal levels, and Gal-3 was not detected in the aqueous and vitreous humors. Without Gal-3 treatment, the corneal wound area spontaneously became smaller in a time-dependent manner; and exogenous recombinant Gal-3 enhanced this wound closure.
Conclusions: :
In monkey corneal epithelial cells, the high level of intracellular Gal-3 may induce spontaneous production of plasma membrane receptors, e.g.; integrin. Increased cell migration observed after treatment with exogenous Gal-3 may have been due to extracellular binding between integrin and Gal-3, and possible Gal-3 binding with ECMs. Since tear fluid contained relatively low levels of Gal-3, exogenous Gal-3 may be a candidate drug to enhance epithelial cell wound healing in diseased human cornea.Dr. Shearer receives consulting fees from, and Dr. Azuma and Ms. Fujii are employees of, Senju Pharmaceutical Co, Ltd.
Keywords: wound healing • cornea: epithelium