Increased expression of nestin in human pterygial epithelium

Abstract

Aim: To investigate the distribution of nestin-positive cells in pterygium, as well as the relationship between nestin-positive cells and proliferative cells in the pathogenesis of pterygium.

Methods: Nine pterygium specimens and 5 normal conjunctiva specimens were investigated. All explanted specimens were immediately immersed in 5-Ethynyl-2'-deoxyuridine, and were subjected to hematoxylin and eosin staining, as well as immunostaining to detect nestin.

Results: Small sub-populations of nestin-expressing cells in both normal and pterygial conjunctiva epithelium were found. These were located at the superficial layer of the epithelium, and were significantly increased (P=0.007) and spread out in the pterygial conjunctiva epithelium, even though these cells were mitotically quiescent.

Conclusion: In pterygium, more nestin-positive cells were present at the superficial layer of the epithelium. With growing scientific evidence that nestin plays an important role in defining various specialized cell types, such as stem cells, cancer cells and angiogenic cells, further investigations on the roles of nestin-expressing cells in pterygium may help to uncover the mechanisms of initiation, development and the prognosis of this disease.

Keywords: distribution; human; nestin; proliferation; pterygium.

Figure 1. Nestin expression in eye epithelium

A: HE stained sections of pterygial epithelium; B: Normal conjunctiva epithelium; C and D: The corresponding fluorescent staining images of Hoechst 33342, nestin as well as the overlay of both Hoechst 33342 and nestin staining for A and B respectively. Nestin staining on pterygium specimens C was significantly brighter and broader than corresponding staining on normal epithelial specimens D. The black lines in A and B indicate the borders of nestin-positive areas observed under microscopy; E: The method of measuring the thickness of fluorescence-stained sections. The ‘1’ represents thickness of Hoechst 33342 stained section, while the ‘2’ represents thickness of nestin-stained section; F: The percentage of thickness of nestin-stained section with respect to thickness of Hoechst 33342 stained section. The percentage of nestin-positive staining area depth=100×1/2. There was significantly thicker nestin-positive area in pterygial epithelium compared to normal epithelium (P=0.007). A, B: ×40; C, D: ×100; E: ×400.

Figure 2. Relationship between EdU-positive and nestin-positive cells in pterygium

A: EdU-positive cells are located in close proximity to the stratumbasale of the pterygium epithelium (×200). Yellow circles represent the capillary area. Arrows indicate EdU-positive cells; B: A blow-up of the EdU-stained areas within the yellow square box inset of A, with and without overlap with the Hoechst 33342-stained nuclei (×400); C: EdU-positive cells were interspersed with nestin-positive cells (×600), while nestin-stained cells did not overlap with Hoechst 33342-stained nuclei.