Purpose:
Neural crest-derived cells (NCC) give rise to the stroma and endothelium of the cornea, an avascular organ whose transparency is critical for vision. However, the basic mechanisms of how pro-angiogenic and anti-angiogenic factors are regulated in the corneal stroma remain unknown. Mutations in human FOXC1 are associated with autosomal-dominant Axenfeld-Rieger Syndrome. In this study, we investigate the NCC-specific roles of Foxc1 in corneal avascularity.
Methods:
Conditional mutant mice for Foxc1 were generated by crossing Foxc1F/F mice with Wnt1-Cre mice to make tissue-specific deletion of Foxc1 specifically in the neural crest lineage. Corneal flat mounts in NCC-specific Foxc1 mutant embryos and adult mice were performed to analyze the blood and lymphatic vessel formation using CD31 and LYVE1 antibodies, respectively. In alkali-burn induced cornea neovascularization (CNV) model, VEGF inhibitor (SU5416; 25 mg/kg body weight) was i.p. injected daily to control and mutant mice for 7 days, and the effects of the VEGF inhibitor on CNV were subsequently examined by corneal flat mounts.
Results:
NCC-specific Foxc1 mutants exhibit CNV (E14.5 to E15.5). NCC-specific Foxc1 mutants also show corneal lymphangiogenesis (E17.5 to E18.0). In the alkali-burn model without VEGF inhibition, corneas of adult Foxc1+/- and NCC-specific Foxc1F/+ mutant mice have increased CNV and lymphangiogenesis, compared with those of wild-type and control mice, respectively. By contrast, CNV and lymphangiogenesis were significantly reduced in corneas of adult Foxc1+/- and NCC-specific Foxc1F/+ mutant mice by treatment of the VEGF inhibitor.
Conclusions:
The cell-autonomous function of Foxc1 in the neural crest is essential for inhibition of vascular formation in the cornea.
Keywords: cornea: stroma and keratocytes • anterior segment • transcription factors