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.