Unique distribution of thrombospondin-1 in human ocular surface epithelium

Invest Ophthalmol Vis Sci. 2006 Apr;47(4):1352-8. doi: 10.1167/iovs.05-1305.


Purpose: The study was conducted to elucidate the detailed expression pattern of angiogenesis-related factors in human ocular surface epithelium. The focus was factors with significantly higher gene expression in corneal epithelium (CE) than in conjunctival epithelium (CJE).

Methods: The relative gene expression of 36 angiogenesis-related factors was compared in human CE and CJE, by using the introduced amplified fragment-length polymorphism (iAFLP) METHOD: Also examined were the expression patterns in the CE, limbal epithelium (LE), and CJE of factors with significantly higher expression in the CE, by using real-time PCR, in situ hybridization, immunohistochemistry, and immunoelectron microscopy.

Results: Only thrombospondin (TSP)-1 exhibited significantly higher expression in the CE. In situ hybridization and real-time PCR showed TSP-1 transcripts in the basal cells of the CE and LE. Compared with the CJE, they were significantly upregulated at those sites. Immunohistochemistry revealed that TSP-1 was strongly expressed in the basal region of the CE. Its expression was faint in LE and absent in CJE. Immunoelectron microscopy revealed that the CE and LE demonstrated TSP-1 labeling just below the epithelium, in the basal region of basal cells, and occasionally in the basal cell membrane. There was little or no labeling in the CJE.

Conclusions: In the human ocular surface epithelium, basal cells of the CE and LE, but not of the CJE, synthesize TSP-1. High levels of TSP-1 are present only just below the CE. Its unique distribution may be related to corneal avascularity and integrity.

Publication types

  • Comparative Study

MeSH terms

  • Angiogenic Proteins / genetics
  • Angiogenic Proteins / metabolism
  • Conjunctiva / metabolism*
  • Conjunctiva / ultrastructure
  • DNA Primers / chemistry
  • Epithelium / metabolism
  • Epithelium / ultrastructure
  • Epithelium, Corneal / metabolism*
  • Epithelium, Corneal / ultrastructure
  • Gene Amplification
  • Gene Expression Regulation
  • Humans
  • Immunohistochemistry
  • In Situ Hybridization
  • Microscopy, Immunoelectron
  • Middle Aged
  • Polymorphism, Restriction Fragment Length
  • Reverse Transcriptase Polymerase Chain Reaction
  • Thrombospondin 1 / genetics*
  • Thrombospondin 1 / metabolism*
  • Thrombospondin 1 / ultrastructure
  • Up-Regulation


  • Angiogenic Proteins
  • DNA Primers
  • Thrombospondin 1