Objective: Approximately half of chronic spontaneous urticaria (CSU) patients are thought to have an autoimmune pathology, and they are resistant to current treatment approaches. Mesenchymal stem cells (MSCs) are adult cells that have been shown to be useful in many autoimmune pathologies due to their immunomodulation properties. This study aimed to investigate the immunomodulatory effects of MSCs, and exosomes isolated from refractory CSU patients.

Materials and Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from 5 refractory CSU patients and 5 healthy volunteers. The effects of MSCs isolated from CSU patients and healthy MSCs were compared. Co-culture experiments were performed to evaluate the efficacy of Mesenchymal Stem Cells and exosomes on PBMCs of CSU patients and healthy volunteers. To compare the resulting effects, changes in IFN-γ, IL-4, IL-10, IL-17a, and TGF-β cytokines were detected by the ELISA method. Cell proliferations were detected with the CCK-8 kit.

Results: The effects of autologous and allogeneic MSCs on IFN- γ expressions were similar, both providing significant suppression at all cell ratios. However, IL-4 and IL-10 expression of PBMCs co-cultured with allogeneic MSCs significantly decreased while IL-17a and TGF-β expression increased significantly. In addition, our findings indicated that exosomes were capable of significant suppression at low PBMC ratios, regardless of autologous or allogeneic origin, but MSCs were more effective as the number of PBMCs increased.

Conclusion: These preliminary findings from in-vitro experiments suggested that allogeneic MSC, or high-dose exosome administration may be a potential approach for treatment in CSU patients, most of whom are regarded as suffering from an autoimmune disease and resistant to current treatments. However, our findings need to be supported by clinical studies.