Tissue-engineered skin equivalents based on primary isolated fibroblasts and keratinocytes have been shown to be useful tools for functional in vitro tests, including toxicological screenings and drug development. In this study, a commercially available squamous cell carcinoma (SCC) cell line SCC-25 was introduced into epidermal and full-thickness skin equivalents to generate human-based disease-in-a-dish model systems. Interestingly, when cultured either in the epidermis or dermis of full-thickness skin equivalents, SCC-25 cells formed hyper-keratinized tumor cell nests, a phenomenon that is frequently seen in the skin of patients afflicted with SCC. Raman spectroscopy was employed for the label-free cell phenotype characterization within the engineered skin equivalents and revealed the presence of differential protein patterns in keratinocytes and SCC-25 cells. To conclude, the here presented SSC disease-in-a-dish approaches offer the unique opportunity to model SSC in human skin in vitro, which will allow further insight into SSC disease progression, and the development of therapeutic strategies.

The perspective to transplant grafts derived from pluripotent stem cells has gained much attention in recent years. Parthenogenetic stem cells (PSCs) are an alternative pluripotent stem cell type that is attractive as source of grafts for allogeneic transplantations because most PSCs are haploidentical for the major histocompatibility complex (MHC). This reduced immunogenetic complexity of PSCs could tremendously simplify the search for MHC-matched allogeneic stem cells. In this study, we have characterized immunological properties of the MHC haploidentical PSC line A3 (H2d/d) and the heterologous PSC line A6 (H2b/d). Both PSC lines largely lack MHC class I molecules, which present peptides to cytotoxic T lymphocytes (CTLs) and serve as ligands for inhibitory natural killer (NK) receptors. They express ligands for activating NK receptors, including the NKG2D ligand RAE-1, and the DNAM-1 ligands CD112 and CD155. Consequently, both PSC lines are highly susceptible to killing by IL-2-activated NK cells. In vitro-differentiated cells acquire resistance and downregulate ligands for activating NK receptors but fail to upregulate MHC class I molecules. The PSC line A6 and differentiated A6 cells are largely resistant to CTLs derived from T cell receptor transgenic OT-I mice after pulsing of the targets with the appropriate peptide. The high susceptibility to killing by activated NK cells may constitute a general feature of pluripotent stem cells as it has been also found with other pluripotent stem cell types. This activity potentially increases the safety of transplantations, if grafts contain traces of undifferentiated cells that could be tumorigenic in the recipient.

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Herkunft und Eigenschaften von Stammzellen 1.1.1.1 Embryonale Stammzellen (ESC) 1.1.1.2 Induzierte pluripotente Stammzellen (iPSC) 1.1.1.3 Multipotente adulte Stammzellen der Keimbahn (maGSC) 1.1.1.4 Parthenogenetische Stammzellen (PSC) 1.1.2 Schwierigkeiten in der Arbeit mit Stammzellen 1.2 Zytotoxische T-Zellen, ihre Effektormechanismen und Auswirkungen auf Stammzellen 1.2.1 Entwicklung zytotoxischer T-Lymphozyten 1.2.2 Aktivierung zytotoxischer T-Lymphozyten 1.2.3 Effektormechanismen zytotoxischer T-Lymphozyten 1.2.4 Protektionsmechanismen gegen Effektormechanismen von CTL 1.2.5 Auswirkungen von CTL auf Stammzellen 1.3 NK-Zellen, ihre Effektormechanismen und deren Auswirkungen auf Stammzellen 1.3.1 Herkunft natürlicher Killerzellen 1.3.2 Aktivierung von NK-Zellen 1.3.3 Effektormechanismen natürlicher Killerzellen 1.3.4 Auswirkungen von NK-Zellen auf Stammzellen