Abstract
Purpose:
Our lab recently demonstrated that Caveolin 1 (Cav-1), the main structural protein found in caveolae membrane domains, is differentially expressed in basal cells of the limbal epithelium where corneal epithelial stem cells reside. Cav-1 may be responsible for the decreased proliferative capacity of corneal epithelial stem cells found within this niche. The purpose of current studies was to determine the role of Cav-1 in corneal epithelial wound healing and mechanisms by which Cav-1 regulates wound healing.
Methods:
Using an in vivo model of corneal epithelial wound healing, the corneal epithelium was removed from the corneas of wild-type (WT) and global Cav-1 knockout (KO) mice utilizing the Algerbrush II. Wounds were monitored using fluorescein staining and healing was quantitated using ImageJ software. A 33-gauge needle (Hamilton) was used to inject 5 μl of Stealth RNAi (10 μM, Ambion) directed against Cav-1 or Stealth RNAi siRNA Negative Control Med GC (10 μM, Ambion) into the mouse conjunctiva. Twenty-four hours after the subconjunctival injection, the corneas were wounded and quantitated as described above. Knockdown was assessed by Western blot. Cellular proliferation was evaluated in vivo in WT and Cav-1 KO mice utilizing 5-ethynyl-2'-deoxyuridine (EdU, Invitrogen). A CyQUANT (Invitrogen) proliferation assay was used to assess proliferation in vitro in human corneal epithelial cells (HCEC) transfected with siRNA directed against Cav-1 (10 nM, Qiagen) or a negative siRNA control (10 nM, Qiagen).
Results:
Corneal wound healing studies revealed that corneal epithelial wounds healed significantly more quickly over 96 h (P < 0.05) in global Cav-1 KO animals compared to controls. Treatment of corneal epithelial wounds with siRNA directed against Cav-1 resulted in a significant (P < 0.05) increase in wound healing rate than corneas treated with negative control siRNA. In vivo determination of proliferation using EdU indicated a significant (P < 0.05) increase in corneal epithelial cell proliferation in Cav-1 deficient corneas compared to controls. In vitro CyQUANT proliferation studies utilizing HCECs transfected with siRNA against Cav-1 corroborate these in vivo EdU studies.
Conclusions:
These studies strongly indicate that decreased Cav-1 levels lead to an increase in the rate of corneal wound healing. Furthermore, the administration of siRNA directed against Cav-1 may be a viable therapeutic approach for corneal wounds.
Keywords: 482 cornea: epithelium •
765 wound healing •
721 stem cells