Inflammatory niche: Mesenchymal stromal cell priming by soluble mediators

Figure 1 Influence of inflammatory priming on regenerative features of mesenchymal stromal/stem cells under in vitro conditions. Soluble factors in the inflammatory microenvironment, including pro-inflammatory cytokines secreted by immune cells and alarmins released by damaged cells, influence mesenchymal stromal/stem cells’ (MSCs) ability to regenerate tissue by affecting their proliferation, migration and differentiation potential (osteogenic, chondrogenic, adipogenic). When applied in vitro, indicated inflammatory factors differently affect the regenerative properties of MSCs depending on the species or tissue origin of MSCs. Symbols: ↑ and ↓ represent stimulatory or inhibitory activity of priming factor, respectively; ↔ indicates no effects of priming factor. The term ’dual’ indicates the data where priming factor dually affected MSCs function depending on applied concentration or MSCs donor age. The numbers in square brackets indicate the references. IFN-γ: Interferon gamma; TNF-α: Tumor Necrosis Factor alpha; IL: Interleukin; HMGB1: High mobility group box 1; Hsp: Heat shock proteins; MSCs: Mesenchymal stromal/stem cells; h: Human; WJ: Warthon jelly; BM: Bone marrow; r: Rat; UC: Umbilical cord; AT: Adipose tissue; DP: Dental pulp; PDL: Periodontal ligament; SHED: Exfoliated deciduous teeth.

Figure 2 Improved in vivo therapeutic potential of inflammatory primed mesenchymal stromal/stem cells. The inflammatory niche mediators, including proinflammatory cytokines and alarmins, play a key role in triggering the reparative functions of mesenchymal stromal/stem cells, influencing their paracrine secretion, proliferation, differentiation, migration and immunomodulatory potential. When applied in vivo, the improved therapeutic efficiency of inflammatory primed MSCs has been detected in various experimental models. The numbers in square brackets indicate the references. TNF-α: Tumor Necrosis Factor alpha; IL: Interleukin; IFN-γ: Interferon gamma; HMGB1: High mobility group box 1; Hsp: Heat shock proteins; BM: Bone marrow; MSCs: Mesenchymal stromal/stem cells; UC: Umbilical cord; AT: Adipose tissue; DSS: Dextran sulfate sodium.