Development of new lymphatic vessels in alkali‐burned corneas

PURPOSE: Corneal lymphangiogenesis provides an exit route for antigen-presenting cells to regional lymph nodes, inducing immune response. The purpose of this study was to examine the development of corneal lymphatic vessels in alkali-burned corneas. METHODS: Corneal lymphatic vessels were examined by electron microscopy, 5'-nase-alkaline phosphatase (5'-NA-ALP) double enzyme-histochemistry and whole mount immunofluorescence at 6 hr, 1 day, 3 days, and 1, 2, 3, 4, 5, 6, 7 and 8 weeks after rat corneal alkali injury. The expression of vascular endothelial growth factor-C (VEGF-C) protein and mRNA was examined 1, 3, 5, 7, 9, 11 and 14 days after the injury. RESULTS: Corneal lymphangiogenesis developed 3 days after alkaline burns, reached its peak 2 weeks after the injury, decreased gradually and disappeared at the end of the fifth week. The expression of VEGF-C in burned corneas increased dramatically on the third day but disappeared the 14th day after the injury. CONCLUSION: Corneal lymphatic vessels develop after alkaline burns and VEGF-C may play an important role in corneal lymphangiogensis.