title: Adipose tissue-derived stem cells show both immunogenic and immunosuppressive properties after chondrogenic differentiation.
abstract: OBJECTIVE
  The chondrogenic differentiation potential of mesenchymal stromal cells (MSC), as well as their immunosuppressive properties, have been studied extensively. So far, only a few studies have addressed the question of whether MSC still retain their immunosuppressive qualities after transdifferentiation. In particular, the expression of immunogenic markers, such as human leukocyte antigen (HLA)-DR, after differentiation has never been investigated.
  
  
  METHODS
  Chondrogenic transdifferentiation was induced in human adipose tissue-derived stem cell (ADSC) pellet cultures derived from 10 different patients, using 10 ng/mL transforming growth factor (TGF)-β3. Samples were harvested over a time-course of 28 days and analyzed by immunohistochemistry and reverse transcription (RT)-polymerase chain reaction (PCR). The cytokine levels in the supernatants of the samples were measured semi-quantitatively by dot-blots and quantitatively by enzyme-linked immunosorbant assays (ELISA).
  
  
  RESULTS
  Undifferentiated ADSC were negative for chondrogenic markers, as well as HLA-ABC and HLA-DR epitopes in immunofluorescence. In contrast, TGF-β3-induced pellet cultures showed both expression of chondrogenic differentiation markers, such as transcription factor 9 (Sox 9), collagen type IIa and aggrecan, and an up-regulation of HLA-DR, beginning at day 7 after induction. Interferon-γ (INF-γ) is known to up-regulate HLA-DR. Therefore we measured INF-γ levels in the supernatants of TGF-β3-induced pellets and, indeed, INF-γ was up-regulated during chondrogenesis in ADSC pellet cultures. However, both undifferentiated and TGF-β3-induced ADSC also showed expression of immunosuppressive HLA-G and interleukin (IL)-10 up-regulation.
  
  
  CONCLUSIONS
  These results suggest that the immunogenicity of adult stem cell-derived tissue should be tested in animal models before clinical trials for allogeneic engineered tissue are considered.
authors.affiliation: Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University of Wuerzburg, Wuerzburg, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Technau
authors.forename: Katrin
authors.initials: K
authors.lastname: Froelich
authors.forename: Rudolf
authors.initials: R
authors.lastname: Hagen
authors.forename: Norbert
authors.initials: N
authors.lastname: Kleinsasser
mesh_terms: D000273:Adipose Tissue / Q000166:cytology*; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000276:immunology*; D002478:Cells, Cultured; D020219:Chondrogenesis / Q000276:immunology*; D000939:Epitopes / Q000235:genetics / Q000276:immunology; D006684:HLA-DR Antigens / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology*; D007118:Immunoassay; D007371:Interferon-gamma / Q000378:metabolism; D016753:Interleukin-10 / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000276:immunology*; D013347:Subcellular Fractions / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; D000939:Epitopes; D006684:HLA-DR Antigens; D016753:Interleukin-10; D007371:Interferon-gamma