title: Histological assessment of cellular half-life in tissues in vivo.
abstract: The assessment of cellular half-life is of fundamental importance for cell biology and biomedicine. Here, we show that cellular half-life in tissues can be histologically measured under steady state conditions in vivo by analyzing the loss of 5-bromo-2'-deoxyuridine (BrdU)-labeled cells over time after withdrawal of long-term BrdU labeling. To achieve efficient continuous cell labeling, we implanted BrdU-containing subcutaneous slow-release pellets into 12-month-old male Fischer 344 rats, delivering BrdU at a dose of 75 mg/kg per day over 1 (n=20) or 3 weeks (n=20). Four to five rats each were killed directly after the labeling or 1, 3, and 7 weeks post-labeling. Cellular half-life after withdrawal of BrdU was analyzed by nonlinear regression analysis of the labeling index, using a model of one-phase exponential decay. We initially validated our technique in the duodenum, where we determined a half-life of 2.4 days for crypt cells. Next, we applied this method to other tissues, and found a half-life of 2.2 weeks for cardiac endothelial cells, and of 5-6 days for pancreatic duct cells. In conclusion, we believe that this novel approach is an important step forward in the histological assessment of cellular half-life.
authors.affiliation: Department of Biomedical Sciences, Institute of Pathophysiology, University of Veterinary Medicine, Veterinaerplatz 1, 1210, Vienna, Austria. Reinhold.Erben@vu-wien.ac.at
authors.forename: Reinhold G
authors.initials: RG
authors.lastname: Erben
authors.forename: Kathrin I
authors.initials: KI
authors.lastname: Odörfer
authors.forename: Michael
authors.initials: M
authors.lastname: Siebenhütter
authors.forename: Karin
authors.initials: K
authors.lastname: Weber
authors.forename: Sonja
authors.initials: S
authors.lastname: Rohleder
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine / Q000008:administration & dosage*; D049109:Cell Proliferation; D016922:Cellular Senescence; D003331:Coronary Vessels / Q000166:cytology / Q000502:physiology; D004343:Drug Implants; D004386:Duodenum / Q000166:cytology / Q000502:physiology; D042783:Endothelial Cells / Q000502:physiology; D006207:Half-Life; D007150:Immunohistochemistry; D008297:Male; D008954:Models, Biological; D017711:Nonlinear Dynamics; D010183:Pancreatic Ducts / Q000166:cytology / Q000502:physiology; D051381:Rats; D011916:Rats, Inbred F344; D015203:Reproducibility of Results; D013194:Staining and Labeling / Q000379:methods*
chemical_list: D004343:Drug Implants; D001973:Bromodeoxyuridine