Nitric oxide-driven copper homeostasis and osteogenesis in cranial defect regeneration using l-arginine-loaded HKUST-1.

Copper plays a multifaceted role in bone tissue engineering, including regulating osteogenic and chondrogenic differentiation, exhibiting antibacterial activity, and enhancing mechanical properties. However, excessive copper induces a distinctive form of cell death, termed cuproptosis which compromises the biocompatibility of copper-based biomaterials. Cuproptosis relies on oxidative phosphorylation and can be inhibited by the Warburg effect, which is the characteristic of aerobic glycolysis in tumor cells. Therefore, nitric oxide (NO), an endogenous signaling molecule that promotes glycolysis and osteogenesis, may potentially inhibit cuproptosis and promote bone repair in copper-based biomaterials. In this study, a Cu-MOF encapsulating l-arginine was synthesized, capable of sustaining NO release through NOS catalysis and H2O2 consumption. It was found to inhibit the cuproptosis and synergistically promote osteogenesis. Multi-omics analyses revealed that this effect is primarily mediated by upregulating glutathione (GSH) synthesis, downregulating the GABA shunt, and enhancing aerobic glycolysis. Furthermore, GelMA loaded with LA@HK was shown to enhance bone defect repair and angiogenesis, and inhibit inflammatory response. Meantime, LA@HK also maintained antibacterial activity and mechanical performance. This therapy may serve as a simple but effective strategy to mitigate copper-induced cytotoxicity and promote osteogenesis, which also provides a novel metabolic mechanism for osteogenesis mediated by NO.