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Diabetic individuals are frequently associated with increased fracture risk and poor bone healing capacity, and the treatment of diabetic bone defects remains a great challenge in orthopedics. In this study, an antioxidant hydrogel was developed using reduced glutathione grafted gelatine methacrylate (GelMA-g-GSH), followed by 3D printing to form a tissue engineering scaffold, which possessed appropriate mechanical property and good biocompatibility. In vitro studies displayed that benefitting from the sustained delivery of reduced glutathione, GelMA-g-GSH scaffold enabled to suppress the overproduction of reactive oxygen species (ROS) and reduce the oxidative stress of cells. Osteogenic experiments showed that GelMA-g-GSH scaffold exhibited excellent osteogenesis performance, with the elevated expression levels of osteogenesis-related genes and proteins. Further, RNA-sequencing revealed that activation of PI3K/Akt signaling pathway of MC3T3-E1 seeded on GelMA-g-GSH scaffold may be the underlying mechanism in promoting osteogenesis. In vivo, diabetic mice calvarial defects experiment demonstrated enhanced bone regeneration after the implantation of GelMA-g-GSH scaffold, as shown by micro-CT and histological analysis. In summary, 3D-printed GelMA-g-GSH scaffold can not only scavenge ROS, but also promote proliferation and differentiation of osteoblasts by activating PI3K/Akt signaling pathway, thereby accelerating bone repair under diabetes.

Reactive oxygen species (ROS) overproduction and oxidative stress increases bone fragility and fracture risk in long-standing diabetes mellitus cases. In this study, a ROS-reactive drug delivery system was prepared to solve this issue by phenyl sulfide mesoporous silica nanoparticles (PMS) loaded with proanthocyanidin (PC). The effect of PMS/PC on new bone formation under diabetic conditions and the underlying mechanism was investigated in-vitro and in-vivo. The results illustrated that the PC was released from the ROS-reactive PMS/PC triggered by peripheral ROS and then eliminated excessive ROS, which achieved dynamic ROS regulation and reached ROS homeostasis finally. Furthermore, we found PMS/PC promoted osteoblastic differentiation in vitro and increased ossification in vivo by promoting the angiogenesis-osteogenesis coupling via down-regulating the expression of nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) to suppress ROS overproduction, preventing vascular oxidative stress. Therefore, our work has proved a therapeutic potential of ROS-reactive PMS/PC in the treatment of diabetic bone disease and indicates excellent prospects of PMS/PC to depress oxidative stress triggered by excessive ROS which is a key pathological factor in many systematic diseases.