Abstract
Purpose: :
Based on our previous observations of platelet accumulation in the limbus and their apparent contribution to corneal wound repair, we hypothesized that platelet accumulation in the corneal limbus plays an important role in corneal nerve repair after corneal epithelial injury.
Methods: :
A 2mm diameter central epithelial region was mechanically debrided in male C57BL/6J wildtype (WT), P-selectin-/-, TCRdelta-/-, and WT mice with peripheral platelet depletion by platelet-specific antibody (CD42b). Corneas from each group were harvested at different times after wounding. Platelet accumulation and transmigration around vessels in the limbus were examined by deconvolution microscopy. Vertical projections and sub basal nerve density across corneas were measured by objective morphometric techniques.
Results: :
After wounding, significant accumulation of platelets occurred in the corneal limbus at 6 hours, and peaked at 12 hours in the WT. Platelet accumulation in P-selectin-/- and TCRd-/- mice was decreased by 83% and 75%, respectively, at 12 hour (p<0.01). Platelets were evident within limbal vessels as well as in the extravascular space; the percentage of extravascular platelets was 52% in WT, 12% in P-selectin-/- and 19% in TCRd-/- mice. Nerve degeneration from the abraded area to the limbus was evident within the first 24 hours in each strain of mice. In WT mice at 4 days following epithelial abrasion regenerating corneal nerve density was 79% of normal, but just 35%, 34%, and 32% in P-selectin-/-, TCRd-/-, and platelet-depleted animals (p<0.01 for each condition).
Conclusions: :
This study reveals a potential role for platelet accumulation in the limbus in efficient regeneration of corneal nerves after epithelial abrasion.
Keywords: cornea: epithelium • inflammation • nerve fiber layer