Preconditioning with Wound Fluid Enhances Immunosuppressive Properties of Mesenchymal Stromal Cells In Vitro

Immunosuppression is one key feature of mesenchymal stromal cells (MSCs) that has high expectations for therapeutic use. The influence of pro-inflammatory stimuli can modify the characteristics of MSCs and enhance immunosuppressive properties. The local postoperative environment contains cytokines, MSCs, and immune cells in high quantities, and their mutual influence is still unclear. Knowledge of in vivo processes is pivotal for potential therapeutic applications, and therefore, the aim of this study was to investigate the influence of wound fluid (WF) on the immunomodulatory potential of MSCs. CD4+ cells were co-cultured with native or WF-preconditioned MSCs for 5 days. CFSE staining revealed significant suppression of T cell proliferation after co-culture that was even more distinct in co-culture with WF-MSCs. The concentration of IDO-1, TGF-β1 and IFN-γ was higher while TNF-α was reduced in co-culture supernatants, indicating a transition to an anti-inflammatory milieu. In summary, the results provide evidence that the influence of WF alters the immunomodulatory potential of MSCs. These findings should serve as the basis for further investigations with a focus on T cell subpopulations.