Stem Cell-Niche Engineering via Multifunctional Hydrogel Potentiates Stem Cell Therapies for Inflammatory Bone Loss

Effective therapies capable of simultaneously inhibiting inflammation and promoting bone healing remain to be developed for inflammatory bone disease. Stem cell therapies hold great promise for a variety of diseases, but their translation is hampered by low cell survival, rapid clearance, and limited functional integration of transplanted stem cells in target tissues. Herein, a multifunctional hydrogel-based stem cell niche engineering strategy is reported for the treatment of inflammatory bone loss. By rationally integrating different functional modules, an injectable hydrogel-based stem niche is engineered, which possesses temperature-triggered gelling performance, inflammation/oxidative stress-resolving activity, stem-cell binding and survival-enhancing capacity, and osteogenesis-promoting capability. Using ectomesenchymal stem cells (EMSCs), effectiveness of this functionally advanced synthetic stem cell niche is demonstrated in rats with periodontitis, a representative inflammatory bone loss disease. Synergistic effects of the multifunctional hydrogel and EMSCs are also confirmed, with respect to normalizing the pathological microenvironment and improving alveolar bone regeneration in the periodontal tissue. Mechanistically, inflammation/oxidative stress-resolving and osteogenic differentiation promoting capacities of the synthetic stem cell niche are mainly achieved by an incorporated nanotherapy via the GDF15/Atf3/c-Fos axis of the MAPK signaling pathway. Besides periodontitis, the newly engineered hydrogel-stem cell therapies are promising for the treatment of other inflammatory bone defects.