Pericytes are correlated with the permeability of rat corneal neovascular vessels induced by alkali burn

Background Comeal neovascular leakage can lead to edema and secondary scarring. Previous studies have shown that pericytes play a key role in maturation of angiogenesis. The present studies investigate the relationship between vascular permeability and pericyte coverage of endothelial cells in rat corneal neovascular induced by alkali bums. Methods Corneal neovascular vessels induced by alkali bums was performed in Sprague-Dawley rats. Corneas were excised on 1,2, 3, 5, 7 and 10 days after cauterization. The vascular permeability rate was measured by the Evans blue method. The microvessel pericyte coverage index （MPI） was applied to quantify the pericyte coverage through double immunofluorescent staining of frozen sections of corneas with CD31 as the endothelial and α-smooth muscle actin （α-SMA） as the pericyte markers. The correlation between permeability rate and MPI was analyzed. Pericyte coverage was confirmed ultrastructually using transmission electron microscopy. Results The vascular permeability rate was （1.14±0.17）, （0.24±0.08）, （0.29±0.16）, （0.14±0.10）, （0.09±0.06） and （0.05±0.04）μg· ml^-1 · mm^-2respectively on 1, 2, 3, 5, 7 and 10 days after cauterization. The MPI was 0, 16.07%, 11.95%, 43.84%, 73.97% and 86.21% respectively at the above mentioned time points. The correlation coefficient between MPI and the permeability rate was -0.943 （P=-0.005）. Conclusions Pericyte recruitment was significantly correlated with the permeability of comeal neovascularization induced by alkali bums in rats. Therapeutic strategies aiming at anti-leakage should be most effective if they promote pericytes proliferation in the course of corneal neovascularization.