title: Mouse beta cell proliferation is inhibited by thymidine analogue labelling.
abstract: OBJECTIVE
  Long-term labelling of mice with halogenated thymidine analogues is an established method for quantifying the contribution of beta cell proliferation to in vivo beta cell mass expansion in (re)generation models. The method is believed to give accurate information on the accrued number of cycling beta cells over a period of time. Multiple thymidine analogue labelling is applied for evaluating the duration of postmitotic quiescence in beta cells. We hypothesise, however, that long-term labelling by thymidine analogues hampers beta cell proliferation.
  
  
  METHODS
  Thymidine analogues were administered for 7-14 days via the i.p. route to neonatal mice, or via drinking water to young mice with normal pancreases or adult mice with injured pancreases. The proliferation of insulin-positive cells was assessed by their expression of the proliferation markers Ki67 or phosphorylated histone H3 and by their incorporation of nucleotide analogues.
  
  
  RESULTS
  In the mouse models of beta cell proliferation investigated herein, long-term administration of thymidine analogues decreased the percentage of Ki67(+) and phosphorylated histone H3(+) beta cells as compared with administration of normal drinking water. Proliferation was restored by washout of the analogue. Labelling with one analogue decreased the subsequent incorporation of another analogue by beta cells.
  
  
  CONCLUSIONS
  Long-term labelling with halogenated thymidine analogues is a biased method that underestimates the proliferation and re-division potential of mouse beta cells.
authors.affiliation: Diabetes Research Center, Vrije Universiteit Brussel, Laarbeeklaan 103, B1090, Brussels, Belgium.
authors.forename: Mark
authors.initials: M
authors.lastname: Van de Casteele
authors.forename: Ying
authors.initials: Y
authors.lastname: Cai
authors.forename: Gunter
authors.initials: G
authors.lastname: Leuckx
authors.forename: Harry
authors.initials: H
authors.lastname: Heimberg
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D006657:Histones / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism*; D019394:Ki-67 Antigen / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008940:Mitotic Index; D023421:Models, Animal; D013194:Staining and Labeling / Q000379:methods; D013936:Thymidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology*
chemical_list: D006657:Histones; D019394:Ki-67 Antigen; D013936:Thymidine
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