Investigation of immunotherapeutic capabilities of preconditioned human Wharton jelly derived mesenchymal stem cells

Title: Investigation of the Immunotherapeutic Potential of Preconditioned Human Wharton's Jelly-Derived Mesenchymal Stem Cells Objective: The aim of this thesis study is to enhance the immunosuppressive efficacy of Wharton's jelly-derived mesenchymal stem cells (iWJ-MSCs), which possess distinct advantages over other mesenchymal stem cell (MSC) sources in terms of immunomodulatory properties, through preconditioning with interferon-gamma (IFN-γ), a key pro-inflammatory cytokine, and to comprehensively evaluate this effect on human T cells, which serve as an in vitro immune system model. Methods: T cells isolated from peripheral blood and activated with phytohemagglutinin (PHA) to mimic an in vitro immune response were co-cultured with IFN-γ preconditioned iWJ-MSCs. Following preconditioning, the levels of IDO and PGE2 in iWJ-MSCs were quantitatively analyzed using ELISA. To investigate whether IFN-γ contributes to the immunosuppressive effects of iWJ-MSCs on T lymphocytes, various analyses were performed after co-culture, including cell viability and proliferation (CCK-8 assay), apoptosis (Annexin V/PI staining), cell cycle distribution (flow cytometric cell cycle analysis), anti- and pro-inflammatory cytokine levels (TGF-β1, IFN-γ), regulatory T cell (Treg; CD4⁺CD25⁺Foxp3⁺) ratio, T-bet expression, and surface marker/gene expression profiling of T cells (CD3, CD4, CD25, CD45, CD4⁺CD8, and CD69). Results: A significant increase in IDO and PGE2 levels was detected in iWJ-MSCs following IFN-γ preconditioning. After co-culture, T cells exhibited reduced proliferation, an increased rate of apoptosis, and a marked elevation in the proportion of Treg cells. Conclusion: The findings of this study demonstrate that IFN-γ preconditioning enhances the immunomodulatory capacity of iWJ-MSCs and strengthens their ability to suppress T lymphocyte responses. Furthermore, it was observed that this immunosuppressive effect is dependent on both the applied dose and the duration of exposure. Keywords: Human umbilical cord stem cells, ınterferon gamma, preconditioning, cell therapy, immunosuppressive therapy.