Expression Of CD34,AC133,STRO-1,C-Kit In The Pterygium

PURPOSE: To explore involvement of bone marrow-derived stem and progenitor cells in the pathogenesis of pterygium.PATIENTS AND METHODS: Informed consent was obtained from all patients that the head of pterygium has reached the edge of the pupil. Paraffin-embedded pterygia (primary pterygium, n=8, recurrent pterygium, n=4) were serially sectioned and analysed immunohistochemically to determine the expression level of AC133(marker for the primitive haematopoietic progenitors), CD34(Marker for the haematopoietic progenitor cells and endothelium), C-KIT(marker for haematopoietic and stromal progenitor cells), and STRO-1(a differentiation antigen present on bone marrow fibroblast cells and on various nonhaematopoietic progenitor cells). The normal conjunctival tissues for the control group were obtained from the same pterygium eye and 10mm from the outside of the pterygium. The immunohistochemically staining was performed by Envision.Results: On light microscopic observation, abundant progenitor cells originated from bone marrow were seen in the basal epithelium or stroma of all primary and recurrent pterygia tissues, while there were no progenitor cells originated from bone marrow in the control groups. Most of the positive cell numbers were in the head of pterygium. C-KIT positive cells were observed mainly in the basal epithelium ,but also found in the stroma of the pterygium. Cells shapes were different from their stained sites. Cells observed in the stroma showed fibroblast-like and spindle-shaped morphology, whereas cells in the basal epithelial layer were round to ovoid-shaped. The sites and cell shapes of AC133 and CD34 positive cells were similar to C-KIT, but cell numbers varied. C-KIT, AC133 and CD34 positive cells were co-expressed in basal epithelium, also observed in the vascular endothelium.STRO-1 was found in the stroma, not in the basal epithelium. Positively stained sites, cell shapes and numbers in recurrent pterygium were similar to those of primary cases.Conclusion: Multipotential stem and progenitor cells originated from bone marrow may play a role in the pathogenesis of pterygium.