title: In vitro decidualisation of canine uterine stromal cells.
abstract: BACKGROUND
  The uterine response to the presence of embryos is poorly understood in the domestic dog (Canis familiaris). The intimate embryo-maternal cross-talk, which begins following the hatching of blastocysts and embryo attachment leads to strong structural and functional remodelling of the uterus. A part of this process is decidualisation, comprising morphological and biochemical changes that result in formation of maternal stroma-derived decidual cells. These are an integral part of the canine placenta materna, which together with the maternal vascular endothelium are the only cells of the canine endotheliochorial placenta able to resist trophoblast invasion. These cells are also the only ones within the canine placenta expressing the progesterone receptor (PGR). Understanding the decidualisation process thus appears essential for understanding canine reproductive physiology.
  
  
  METHODS
  Here, we investigated the capability of canine uterine stromal cells to decidualise in vitro, thereby serving as a canine model of decidualisation. A dbcAMP-mediated approach was chosen during a time course of 24 - 72 h. Tissue material from six (n = 6) healthy, dioestric bitches was used (approximately 2 weeks after ovulation). Cells were characterized by differential staining, nearly 100 % of which were vimentin-positive. Scanning and transmission electron microscope analyses were applied, and morphological changes were recorded with a live cell imaging microscope. Expression of several decidualisation markers was investigated.
  
  
  RESULTS
  The in vitro cultured stromal cells acquired characteristics of decidual cells when incubated with 0.5 mM dbcAMP for 72 h. Their shape changed from elongated to rounded, while ultrastructural analysis revealed higher numbers of mitochondria and secretory follicles, and an increased proliferation rate. Elevated expression levels of IGF1, IGF2, PRLR and ERα were observed in decidualised cells; PRL and ERβ remained mostly below the detection limit, while PGR remained unaffected. The expression of smooth muscle α actin (αSMA), another decidualisation marker, was strongly induced. Among prostaglandin system members, levels of COX2 (PTGS2) and of PGE2-synthase (PTGES) were upregulated. Expression of the PGE2 receptors, PTGER2 and PTGER4, was clearly detectable.
  
  
  CONCLUSIONS
  An in vitro decidualisation model with canine uterine stromal cells was successfully established, allowing future, more detailed studies to be undertaken on the underlying molecular and endocrine mechanisms of canine decidualisation.
authors.affiliation: Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, CH-8057, Zurich, Switzerland. ewa.kautz@yahoo.com.
authors.forename: Ewa
authors.initials: E
authors.lastname: Kautz
authors.affiliation: Department of Surgery, Faculty of Veterinary Medicine and Animal Sciences, Sector of Anatomy, University of Sao Paulo, Sao Paulo, Brazil. paula.papa1@gmail.com.
authors.forename: Paula
authors.initials: P
authors.lastname: de Carvalho Papa
authors.affiliation: Section of Small Animal Reproduction, Clinic of Reproductive Medicine, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland. ireichler@vetclinics.uzh.ch.
authors.forename: Iris M
authors.initials: IM
authors.lastname: Reichler
authors.affiliation: Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, CH-8057, Zurich, Switzerland. aykutgram@gmail.com.
authors.forename: Aykut
authors.initials: A
authors.lastname: Gram
authors.affiliation: Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, CH-8057, Zurich, Switzerland. boosa@vetanat.uzh.ch.
authors.forename: Alois
authors.initials: A
authors.lastname: Boos
authors.affiliation: Institute of Veterinary Anatomy, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, CH-8057, Zurich, Switzerland. kowalewski@vetanat.uzh.ch.
authors.forename: Mariusz P
authors.initials: MP
authors.lastname: Kowalewski
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology; D003656:Decidua / Q000187:drug effects / Q000378:metabolism*; D004285:Dogs; D010064:Embryo Implantation / Q000502:physiology*; D047628:Estrogen Receptor alpha / Q000378:metabolism; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D010920:Placenta / Q000187:drug effects / Q000378:metabolism*; D011247:Pregnancy; D017526:Receptor, IGF Type 1 / Q000378:metabolism; D011981:Receptors, Prolactin / Q000378:metabolism; D017154:Stromal Cells / Q000187:drug effects / Q000378:metabolism*
chemical_list: D047628:Estrogen Receptor alpha; D011981:Receptors, Prolactin; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D000242:Cyclic AMP; D017526:Receptor, IGF Type 1