title: Identification of adult stem cells in Schwalbe's line region of the primate eye.
abstract: OBJECTIVE
  To identify stem cells in the chamber angle of the monkey eye by detection of 5-bromo-2'-deoxyuridine (BrdU) long-term retention.
  
  
  METHODS
  Four cynomolgus monkeys were treated with BrdU via subcutaneous pumps for 4 weeks. The eyes of two animals were processed immediately thereafter (group 1) while in the other animals, BrdU treatment was discontinued for 4 weeks to allow identification of cells with long-term BrdU retention (group 2). The number of BrdU-positive nuclei was quantified, and the cells were characterized by immunohistochemistry and transmission electron microscopy (TEM).
  
  
  RESULTS
  The number of BrdU-positive cells was higher at Schwalbe's line covering the peripheral end of Descemet's membrane than in Schlemm's canal (SC) endothelium, trabecular meshwork (TM), and scleral spur (SS). Labeling with BrdU in SC, TM, and SS was less intense and the number of labeled cells was smaller in group 2 than in group 1. In contrast, in cells of Schwalbe's line the intensity of BrdU staining and the number of BrdU-positive cells was similar when group 1 and 2 monkeys were compared with each other, indicating long-term BrdU retention. Cells that were BrdU-positive in Schwalbe's line region stained for the stem cell marker OCT4. Details of a stem cell niche in Schwalbe's line region were identified by TEM.
  
  
  CONCLUSIONS
  We provide evidence for a niche in the Schwalbe's line region harboring cells with long-term BrdU retention and OCT4 immunoreactivity. The cells likely constitute a population of adult stem cells with the capability to compensate for the loss of TM and/or corneal endothelial cells.
authors.affiliation: Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany.
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Braunger
authors.affiliation: Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany.
authors.forename: Bahar
authors.initials: B
authors.lastname: Ademoglu
authors.affiliation: Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany.
authors.forename: Sebastian E
authors.initials: SE
authors.lastname: Koschade
authors.affiliation: Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Fuchshofer
authors.affiliation: Department of Ophthalmology & Visual Sciences, University of Wisconsin School of Medicine & Public Health, Madison, Wisconsin, United States.
authors.forename: B'Ann T
authors.initials: BT
authors.lastname: Gabelt
authors.affiliation: Department of Ophthalmology & Visual Sciences, University of Wisconsin School of Medicine & Public Health, Madison, Wisconsin, United States.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Kiland
authors.affiliation: Department of Ophthalmology & Visual Sciences, University of Wisconsin School of Medicine & Public Health, Madison, Wisconsin, United States.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Hennes-Beann
authors.affiliation: Wisconsin National Primate Research Center, University of Wisconsin, Madison, Wisconsin, United States.
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Brunner
authors.affiliation: Department of Ophthalmology & Visual Sciences, University of Wisconsin School of Medicine & Public Health, Madison, Wisconsin, United States.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Kaufman
authors.affiliation: Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany.
authors.forename: Ernst R
authors.initials: ER
authors.lastname: Tamm
mesh_terms: D053687:Adult Stem Cells / Q000378:metabolism / Q000648:ultrastructure*; D000818:Animals; D000867:Anterior Chamber / Q000166:cytology* / Q000378:metabolism; D001973:Bromodeoxyuridine / Q000493:pharmacokinetics; D008252:Macaca fascicularis; D008253:Macaca mulatta; D046529:Microscopy, Electron, Transmission; D015203:Reproducibility of Results; D041623:Tomography, Optical Coherence
chemical_list: D001973:Bromodeoxyuridine
keywords: BrdU retention; Schwalbe's line; monkey eye; stem cells