Osteoblast/Osteoclast and Immune Cocktail Therapy of an Exosome/Drug Delivery Multifunctional Hydrogel Accelerates Fracture Repair

The osteoblast/osteoclast and M1/M2 macrophage ratios play critical roles in delayed fracture healing. Robust osteoblast differentiation and M2 macrophage polarization can substantiality promote fracture repair; however, the combined effect of these strategies has not been previously studied. In this study, we constructed a cocktail therapy to simultaneously regulate the osteoblast/osteoclast and M1/M2 macrophage balance. The cocktail therapy composed of a natural polymer hyaluronic-acid-based hydrogel (HA hydrogel, which has a tissue-adhesive, injectable, self-healing, anti-inflammation profile), engineered endothelial cell-derived exosomes (EC-Exos^miR-26a-5p), and APY29, an IRE-1α inhibitor. This allowed for specific delivery of EC-Exos^miR-26a-5p and APY29 for osteoblast/osteoclast and macrophage regulation, respectively. The results suggested that the cocktail therapy exerted pro-fracture repair effects with each of its components established as indispensable. The assessed cocktail therapy provides insight into synergistic strategies and is useful for developing more suitable pro-fracture repair therapy.