Inflammatory priming of mesenchymal stromal cells enhances its secretome potential through secretion of anti-inflammatory and ECM modulating factors: Insights into proteomic and functional properties

Regenerative properties of stem cells have been an area of intensive research over the past decade. Mesenchymal Stromal Cells (MSCs), known for their immunoevasive nature, are recognized for their immunomodulatory properties and are being explored widely to treat various inflammatory diseases. MSCs are reported to have varied secretome components based on their tissue origin, and secretome is now being explored as a cell-therapy alternative. This study explores the efficiency of priming MSCs with a combination of inflammatory proteins and compares with individual protein priming. MSCs isolated from Wharton's jelly of umbilical cord were characterized by checking surface markers and multi-lineage differentiation potential. MSCs were cultured in presence of IL-1β, TNF-α and IL-17 cocktail. Following priming, WJ-MSCs exhibited elevated gene expression, with TSG-6 increasing 2-7-fold, IL-6 by 27-fold, and CCL-20 reaching up to 720-fold compared to unprimed control, while ELISA demonstrated the absence of residual inflammatory priming proteins in the MSC secretome with <2 ng/mL/5.5 × 10⁶ cells residue in the secretome. Proteomic analysis indicated enhanced tissue regeneration related processes of primed secretome. Functionally, primed secretome was able to polarize macrophages from inflammatory M1 phenotype to anti-inflammatory M2 phenotype, wherein it showed up to 10 folds diminished angiogenic potential and ability to polarize macrophages towards M2 phenotype. This preconditioning strategy can be used to enhance the potential of MSC secretome, having various applications in targeting inflammatory diseases.