Adipose tissue-derived stem cells show both immunogenic and immunosuppressive properties after chondrogenic differentiation.
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.
Technau
Antje
A
Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University of Wuerzburg, Wuerzburg, Germany.
Froelich
Katrin
K
Hagen
Rudolf
R
Kleinsasser
Norbert
N
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
D015415:Biomarkers; D000939:Epitopes; D006684:HLA-DR Antigens; D016753:Interleukin-10; D007371:Interferon-gamma