Objective Pterygium is a common, benign fibrovascular disease of the human ocular surface that can impair vision and restrict ocular mobility if not removed. Surgical excision is the most common form of treatment; however, non-surgical therapeutics are being developed, which target the angiogenic component of this disease. Nestin is a class VI intermediate filament protein expressed in neuroepithelium with an emerging role in angiogenesis and tumourigenesis. Given the tumour-like and angiogenic features of pterygia, we postulated that nestin partakes in its development.

Methods and Results Formalin-fixed, paraffin-embedded pterygia and donor-matched conjunctiva (n=22) were obtained, sectioned and stained for nestin by immunohistochemistry and immunofluorescence. Immunoreactivity for nestin was semi-quantified and microvessel density counted. Significantly, higher nestin expression was identified in pterygium epithelial cells and blood vessels compared with matched normal conjunctiva. Interestingly, a high proportion of the pterygium specimens displayed nuclear staining for nestin within the basal and suprabasal epithelium. Immunofluorescence was used to simultaneously detect nestin in CD31⁺ blood vessels; however, this protein was absent from Lyve-1⁺ lymphatic vessels. In addition, blood and lymphatic vessel density was significantly higher in pterygia compared with corresponding control conjunctiva.

Conclusions These results demonstrate for the first time the expression of nestin in the pterygium vasculature and indicate that this protein may play a central role in the angiogenic response, which characterises this disease. Targeting nestin pharmacologically could be considered as an alternative or adjuvant therapeutic strategy.