A metamaterial scaffold beyond modulus limits: enhanced osteogenesis and angiogenesis of critical bone defects
Yu Qin, Zehao Jing, Da Zou, Youhao Wang, Hongtao Yang, Kai Chen, Weishi Li, Peng Wen, Yufeng Zheng
Abstract
Metallic scaffolds have shown promise in regenerating critical bone defects. However, limitations persist in achieving a modulus below 100 MPa due to insufficient strength. Consequently, the osteogenic impact of lower modulus and greater bone tissue strain ( > 1%) remains unclear. Here, we introduce a metamaterial scaffold that decouples strength and modulus through two-stage deformation. The scaffold facilitates an effective modulus of only 13 MPa, ensuring adaptability during bone regeneration. Followed by a stiff stage, it provides the necessary strength for load-bearing requirements. In vivo, the scaffold induces > 2% callus strain, upregulating calcium channels and HIF-1α to enhance osteogenesis and angiogenesis. 4-week histomorphology reveals a 44% and 498% increase in new bone fraction versus classic scaffolds with 500 MPa and 13 MPa modulus, respectively. This design transcends traditional modulus-matching paradigms, prioritizing bone tissue strain requirements. Its tunable mechanical properties also present promising implications for advancing osteogenesis mechanisms and addressing clinical challenges. Metallic bone scaffolds can’t be soft and strong. Here, the authors design a two-stage metamaterial scaffold with decoupled strength and modulus. By inducing greater tissue strain, it enhances osteogenesis and angiogenesis in ulnar defects model.