title: Label retaining and stem cell marker expression in the developing rat urinary bladder.
abstract: OBJECTIVE
  To identify potential stem cells in urinary bladder by label-retaining cell (LRC) strategy and immunostaining for putative stem cell markers.
  
  
  METHODS
  Newborn rats were intraperitoneally injected with 5-ethynyl-2-deoxyuridine (EdU) and their bladders harvested at 4 different time points afterward. The bladders were processed for EdU staining and immunofluorescence staining for stem cell markers Lgr5, CD34, SSEA-1, and c-kit. EdU-positive cells were counted and colocalization with stem cell markers determined.
  
  
  RESULTS
  At day 1 post-EdU injection, 1804.0 ± 227.7 bladder cells were labeled in each cross-section. As time increased, fewer bladders remained labeled, dropping to 236.5 ± 53.0 cells per field. In the 1-day bladders, 27.5% ± 4.9% of the epithelial cells were labeled as compared to 12.1% ± 2.8% in the detrusor. The labeling rates in these 2 tissue compartments gradually equalized, reaching at approximately 5.5% in the 8-week samples. Distribution of LRC was random, without preferential labeling of basal cells. Lgr5 and SSEA-1 were detectable in the urothelium, and CD34 and c-kit in the lamina propria and detrusor. Approximately 30%-40% of c-kit-positive cells were EdU positive.
  
  
  CONCLUSIONS
  Labeling of bladder cells by EdU occurred randomly, and label retaining was not associated with expression of Lgr5, CD34, or SSEA-1. The strong association between label retaining and c-kit expression appears to relate to interstitial cells of Cajal, not stem cells.
authors.affiliation: Knuppe Molecular Urology Laboratory, Department of Urology, School of Medicine, University of California, San Francisco, California 94143-0738, USA.
authors.forename: Haiyang
authors.initials: H
authors.lastname: Zhang
authors.forename: Guiting
authors.initials: G
authors.lastname: Lin
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Qiu
authors.forename: Hongxiu
authors.initials: H
authors.lastname: Ning
authors.forename: Lia
authors.initials: L
authors.lastname: Banie
authors.forename: Tom F
authors.initials: TF
authors.lastname: Lue
authors.forename: Ching-Shwun
authors.initials: CS
authors.lastname: Lin
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D018952:Antigens, CD34 / Q000096:biosynthesis / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D003857:Deoxyuridine / Q000031:analogs & derivatives* / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D016256:Lewis X Antigen / Q000096:biosynthesis / Q000378:metabolism*; D009092:Mucous Membrane / Q000166:cytology; D009130:Muscle, Smooth / Q000166:cytology; D019009:Proto-Oncogene Proteins c-kit / Q000096:biosynthesis / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D013234:Stem Cells / Q000378:metabolism*; D001743:Urinary Bladder / Q000166:cytology* / Q000378:metabolism; D019459:Urothelium / Q000166:cytology
chemical_list: D018952:Antigens, CD34; D015415:Biomarkers; D016256:Lewis X Antigen; D043562:Receptors, G-Protein-Coupled; D019009:Proto-Oncogene Proteins c-kit; C031086:5-ethynyl-2'-deoxyuridine; D003857:Deoxyuridine