title: Establishment and Characterization of a Tumor Stem Cell-Based Glioblastoma Invasion Model.
abstract: OBJECTIVE
  Glioblastoma is the most frequent and malignant brain tumor. Recurrence is inevitable and most likely connected to tumor invasion and presence of therapy resistant stem-like tumor cells. The aim was therefore to establish and characterize a three-dimensional in vivo-like in vitro model taking invasion and tumor stemness into account.
  
  
  METHODS
  Glioblastoma stem cell-like containing spheroid (GSS) cultures derived from three different patients were established and characterized. The spheroids were implanted in vitro into rat brain slice cultures grown in stem cell medium and in vivo into brains of immuno-compromised mice. Invasion was followed in the slice cultures by confocal time-lapse microscopy. Using immunohistochemistry, we compared tumor cell invasion as well as expression of proliferation and stem cell markers between the models.
  
  
  RESULTS
  We observed a pronounced invasion into brain slice cultures both by confocal time-lapse microscopy and immunohistochemistry. This invasion closely resembled the invasion in vivo. The Ki-67 proliferation indexes in spheroids implanted into brain slices were lower than in free-floating spheroids. The expression of stem cell markers varied between free-floating spheroids, spheroids implanted into brain slices and tumors in vivo.
  
  
  CONCLUSIONS
  The established invasion model kept in stem cell medium closely mimics tumor cell invasion into the brain in vivo preserving also to some extent the expression of stem cell markers. The model is feasible and robust and we suggest the model as an in vivo-like model with a great potential in glioma studies and drug discovery.
authors.affiliation: Department of Pathology, Odense University Hospital, Denmark, Odense C, Denmark.|Department of Clinical Research, University of Southern Denmark, Odense C, Denmark.
authors.forename: Stine Skov
authors.initials: SS
authors.lastname: Jensen
authors.affiliation: Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense C, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Meyer
authors.affiliation: Department of Pathology, Odense University Hospital, Denmark, Odense C, Denmark.|Department of Clinical Research, University of Southern Denmark, Odense C, Denmark.
authors.forename: Stine Asferg
authors.identifier: http://orcid.org/0000-0001-9963-7295
authors.initials: SA
authors.lastname: Petterson
authors.affiliation: Department of Pathology, Odense University Hospital, Denmark, Odense C, Denmark.|Department of Neurosurgery, Odense University Hospital, Odense C, Denmark.
authors.forename: Bo
authors.initials: B
authors.lastname: Halle
authors.affiliation: Department of Pathology, Odense University Hospital, Denmark, Odense C, Denmark.|Department of Clinical Research, University of Southern Denmark, Odense C, Denmark.
authors.forename: Ann Mari
authors.initials: AM
authors.lastname: Rosager
authors.affiliation: Department of Pathology, Odense University Hospital, Denmark, Odense C, Denmark.|Department of Clinical Research, University of Southern Denmark, Odense C, Denmark.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Aaberg-Jessen
authors.affiliation: Department of Clinical Research, University of Southern Denmark, Odense C, Denmark.|Department of Clinical Genetics, Odense University Hospital, Odense C, Denmark.
authors.forename: Mads
authors.initials: M
authors.lastname: Thomassen
authors.affiliation: Department of Clinical Research, University of Southern Denmark, Odense C, Denmark.|Department of Clinical Genetics, Odense University Hospital, Odense C, Denmark.
authors.forename: Mark
authors.initials: M
authors.lastname: Burton
authors.affiliation: Department of Clinical Research, University of Southern Denmark, Odense C, Denmark.|Department of Clinical Genetics, Odense University Hospital, Odense C, Denmark.
authors.forename: Torben A
authors.initials: TA
authors.lastname: Kruse
authors.affiliation: Department of Pathology, Odense University Hospital, Denmark, Odense C, Denmark.|Department of Clinical Research, University of Southern Denmark, Odense C, Denmark.
authors.forename: Bjarne Winther
authors.initials: BW
authors.lastname: Kristensen
mesh_terms: D000818:Animals; D015415:Biomarkers; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology*; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D004195:Disease Models, Animal; D005260:Female; D005909:Glioblastoma / Q000378:metabolism* / Q000473:pathology*; D064593:Heterografts; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D018613:Microscopy, Confocal; D009361:Neoplasm Invasiveness; D014411:Neoplastic Stem Cells / Q000378:metabolism*; D051381:Rats; D018874:Spheroids, Cellular; D014407:Tumor Cells, Cultured
chemical_list: D015415:Biomarkers