Purpose: To study the role played by HB-EGF in corneal epithelial wound healing.
Methods: A 2-mm corneal epithelial wound was created in keratinocyte-specific, HB-EGF-deficient mice--HB(lox/lox):K-5Cre (HB(-/-))--and the speed of wound healing was compared with that in wild-type (WT) mice. Cultured confluent mouse corneal epithelial cells (MCECs) from WT and HB(-/-) mice were scraped, and the bare area was measured. The proliferation of MCECs was determined by BrdU incorporation. The degree of attachment of WT and HB(-/-) MCECs was also determined. The mRNA expression of EGF family and cell adhesion molecules was determined by real-time PCR.
Results: Corneal epithelial wound healing was significantly delayed in HB(-/-) mice, and the expression of HB-EGF was detected at the leading edge of the wound in HB(lox/+):K5-Cre (HB(+/-)) mice by the presence of lacZ staining. The wound closure was significantly impaired in HB(-/-) MCECs and was improved by adding HB-EGF. The number of BrdU-positive MCECs of WT and HB(-/-) mice was not significantly different, and both increased to different degrees when HB-EGF was added. The adhesion of isolated HB(-/-) MCECs was lower than that of WT MCECs, but the degree of adhesion was restored by adding HB-EGF. The expression of epiregulin was upregulated in HB(-/-) MCECs, and α6- and β1-integrin were upregulated by adding HB-EGF.
Conclusions: HB-EGF plays an important role in corneal epithelial cell healing by enhancing cellular attachment and part of cell proliferation.