title: Mesenchymal-epithelial cell interactions and proteoglycan matrix composition in the presumptive stem cell niche of the rabbit corneal limbus.
abstract: OBJECTIVE
  To investigate whether mesenchymal-epithelial cell interactions, similar to those described in the limbal stem cell niche in transplant-expired human eye bank corneas, exist in freshly enucleated rabbit eyes and to identify matrix molecules in the anterior limbal stroma that might have the potential to help maintain the stem cell niche.
  
  
  METHODS
  Fresh limbal corneal tissue from adult Japanese white rabbits was obtained and examined in semithin resin sections with light microscopy, in ultrathin sections with transmission electron microscopy, and in three-dimensional (3D) reconstructions from data sets of up to 1,000 serial images from serial block face scanning electron microscopy. Immunofluorescence microscopy with five monoclonal antibodies was used to detect specific sulfation motifs on chondroitin sulfate glycosaminoglycans, previously identified in association with progenitor cells and their matrix in cartilage tissue.
  
  
  RESULTS
  In the rabbit limbal cornea, while no palisades of Vogt were present, the basal epithelial cells stained differentially with Toluidine blue, and extended lobed protrusions proximally into the stoma, which were associated with interruptions of the basal lamina. Elongate processes of the mesenchymal cells in the superficial vascularized stroma formed direct contact with the basal lamina and basal epithelial cells. From a panel of antibodies that recognize native, sulfated chondroitin sulfate structures, one (6-C-3) gave a positive signal restricted to the region of the mesenchymal-epithelial cell associations.
  
  
  CONCLUSIONS
  This study showed interactions between basal epithelial cells and subjacent mesenchymal cells in the rabbit corneal limbus, similar to those that have been observed in the human stem cell niche. A native sulfation epitope in chondroitin sulfate glycosaminoglycans exhibits a distribution specific to the connective tissue matrix of this putative stem/progenitor cell niche.
authors.affiliation: Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Maindy Road, Cardiff, UK; Department of Ophthalmology, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto-shi, Kyoto, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Yamada
authors.affiliation: Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Maindy Road, Cardiff, UK.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Young
authors.affiliation: Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Maindy Road, Cardiff, UK.
authors.forename: Philip N
authors.initials: PN
authors.lastname: Lewis
authors.affiliation: Department of Ophthalmology, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto-shi, Kyoto, Japan.
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Shinomiya
authors.affiliation: Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Maindy Road, Cardiff, UK.
authors.forename: Keith M
authors.initials: KM
authors.lastname: Meek
authors.affiliation: Department of Ophthalmology, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto-shi, Kyoto, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kinoshita
authors.affiliation: Connective Tissue Biology Laboratories, School of Biosciences, The Sir Martin Evans Building, Cardiff University, Museum Avenue, Cardiff, UK.
authors.forename: Bruce
authors.initials: B
authors.lastname: Caterson
authors.affiliation: Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Maindy Road, Cardiff, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Quantock
mesh_terms: D000818:Animals; D001485:Basement Membrane / Q000378:metabolism / Q000648:ultrastructure; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D019573:Epithelium, Corneal / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D021621:Imaging, Three-Dimensional; D016850:Limbus Corneae / Q000166:cytology* / Q000378:metabolism; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D011509:Proteoglycans / Q000378:metabolism; D011817:Rabbits; D055153:Stem Cell Niche
chemical_list: D011509:Proteoglycans