Involvement of Endothelial Precursors from Bone Marrow in Pterygium

Abstract

Abstract: : Purpose: We evaluated the involvement of endothelial precursors and its related activating factors in pterygium, then measured chemotactic factors both locally and systemically before and after operation. And also we confirmed increased mobilization of endothelial progenitors from bone marrow. Methods: Primary (n=15), recurrent pterygium (n=10) and normal control cases (n=5) were selected for this research. Immunohistochemical staining with endothelial precursor markers (CD31, CD34, c–kit, VEGF–R1(Flt–1) and VEGF–R2(Flk–1)) and related factors (hypoxia inducible factor–1α (HIF–1α), NF–ΚB and VEGF) were performed. Their producing site was examined, too. Chemotactic factors (IL–1ß, GM–CSF, VEGF and substance–P) were measured in patient’s tear and serum by using ELISA on pre operation and post operation 1^st, 3^rd and 5^th day. To confirm the mobilization of endothelial precursors systemically, flowcytometry of peripheral blood with CD34 and c–kit was also done. Results: The CD31, c–kit and Flt–1 positive endothelial precursor cells were revealed coincidently in stroma, which were clustered around small vessels and formed rosette pattern. These foci were increased remarkably in recurrent pterygium compared to in primary pterygium. HIF–1α, as producing factor of VEGF was observed mainly in epithelium. NF–ΚB was expressed co–localized with HIF–1α in nucleus. Substance–P was increased on 1^st day and VEGF was elevated from 3^rd day of operation in ELISA with serum and tear. These activating factors were increased more significantly in recurrent pterygium. The CD34 and c–kit positive endothelial precursors were increased on 3^rd∼5^th day of operation especially in recurrent cases. Conclusions: Co–expressed CD31, c–kit and Flt–1 could be applied as marker of endothelial precursor. Above results demonstrate that endothelial precursors from bone marrow were involved in pathogenesis and recurrence of pterygium. This involvement was mediated by chemotactic factors in both locally and systemically.

Keywords: Pterygium • immunohistochemistry • flow cytometry