Effect of Constant Inflammation on In Vitro Expanded Adipose-derived Mesenchymal Stromal Cells.

Human adipose-derived mesenchymal stromal cells (AD-MSCs) are known for their immunomodulatory responses to inflammation, a key trait for their therapeutic use in tissue injury and chronic inflammatory diseases. However, the effects of constant inflammation on their transcriptomic profile, proliferative capacity, and immunosuppressive potential remain largely unexplored. To investigate this, we evaluated the in vitro response of human AD-MSCs from three donors expanded across seven passages under, non-inflamed (DMEM), acute (IFNγ-24 h) and constant (IFNγ-C) inflammatory conditions. Bulk RNA-sequencing results demonstrated that AD-MSCs respond significantly to inflammatory stimuli. Both acute and constant inflammation induced extensive transcriptomic alterations, with differentially expressed genes related to cell cycle regulation, DNA replication, metabolism, and immunomodulation. Notably, constant inflammation was associated with a transcriptomic shift toward oxidative phosphorylation (OXPHOS). Moreover, microscopy analysis revealed a significant reduction in AD-MSCs proliferative capacity under constant inflammation, as evidenced by lower cumulative population doubling and the appearance of senescence-like morphological changes in early passages when compared to non-inflamed (DMEM) and acute inflammatory (IFNγ-24 h) conditions. Despite proliferation being impaired, co-culture assays with PBMCs demonstrated that under constant inflammation AD-MSCs immunosuppressive potential was maintained in early and late passages. Therefore, our results provide novel insights into the dual effects of constant inflammation on AD-MSCs, impairing cell proliferation while maintaining their immunosuppressive capacity. Understanding AD-MSCs' behaviour in chronically inflamed microenvironments is essential for optimizing AD-MSCs' clinical applications.