Cytological study on rat corneal new blood vessel after alkali burn / 中华实验眼科杂志

ABSTRACT

Background Microvessels are composed of two interacting cell types endothelial cells and pericytes. Over the past decades, studies of corneal angiogenesis have concentrated mainly on endothelial cells, while interest in pericytes has lagged behind. Objective The present study aimed to investigate the recruitment of vascular endothelial cells and pericytes in rat corneas after alkali burn. Methods Corneal alkali burn models were established in the right eyes of 36 adult SPF SD rats by putting 4 mm medicators containing a 1% 1 mol/L NaOH solution at the central corneas for 30 seconds, and 3 matched normal rats were used as controls. Corneas were excised 1,2,3,5,7 and 10 days after surgery. Frozen sections that parallel with the corneoscleral limbus were constructed. Double immunofluorescence staining was used to observe the dynamic expression of CD31 and α-smooth muscle actin (α-SMA) in corneal tissue for the evaluation of the number of endothelial cells and pericytes. The pericyte coverage index (PCI) was calculated to quantify the recruitment of pericytes to neovascular sites. The use of experimental animals followed the Statement of Association for Research in Vision and Ophthalmology. Results CD31 was expressed in the superficial stromal layer of the cornea on the 1 st day, showing the presence of red fluoresence. The positive cell number for CD31 was gradually increased with the passage of time and proceeded into the deep stromal layer from days 2 through 5 but decreased after that. However,α-SMA was positively expressed on the 2nd day in the cornea after alkali burn with the presence of green fluorescence. The positive cell number for α-SMA was less than those of CD31 throughout the experimental period. The PCI was 0, 16.07%, 11.95%, 43.84%, 73.97% and 86. 21% , respectively, 1,2,3,5,7 and 10 days after surgery. Conclusion Pericytes recruitment to corneal new vessels may play a key role in the stabilization and maturation of angiogeneis.