Fast shape memory function and personalized PLTMC/SIM/MBG composite scaffold for bone regeneration

Orthopedic clinical practice faces significant challenges in treating critical-sized bone defects due to extensive tissue damage and prolonged healing. To address these limitations, this study integrated shape-memory polymers with 3D printing to engineer bioactive scaffolds composed of poly(l-lactide-co-trimethylene carbonate) (PLTMC), simvastatin (SIM), and mesoporous bioactive glass (MBG) via low-temperature rapid prototyping. The PLTMC/SIM/MBG composite scaffold exhibited exceptional porosity (78.5% ± 1.5%) and load-bearing compressive strength (66.33 ± 1.44 MPa at 30% MBG). In addition, its thermoresponsive shape-memory behavior enabled intraoperative molding to precisely conform to defect geometries, while the sustained release of SIM and MBG ionic exchange together created a bioactive microenvironment. Mechanistically, the scaffold activated the Wnt pathway to enhance the osteogenic differentiation of mesenchymal stem cells, maintaining cytocompatibility. In vivo, directional bone regeneration occurred along the degradable scaffold, driven by synergistic topographical guidance from 3D-printed pores and biochemical cues from SIM and MBG. The shape-adaptive design preserved mechanical continuity with the host bone during remodeling. These results demonstrate a personalized solution for large defects, merging surgical adaptability through shape-memory functionality with bioactive efficacy via structural and biochemical synergy, overcoming the limitations of conventional implants in anatomical matching and regenerative performance. Inspired by the concept of designing functional materials, we have innovatively fabricated a novel PLTMC/SIM/MBG composite scaffold via low - temperature 3D printing technology, endowing it with body temperature - responsive shape memory functionality. This cutting - edge scaffold adopts a multi - pronged strategy to promote bone regeneration: the mesopores of MBG enable the controlled release of SIM and facilitate Ca²⁺/SiO₄⁴⁻ ion exchange; its optimized porosity of 78.5% and compressive strength of 66.33 MPa are tailored to meet the mechanical demands of cancellous bone; activation of the Wnt/β - catenin pathway effectively promotes the osteogenic differentiation of BMSCs; and in the rat femoral defect model, it showcases remarkable performance in achieving orderly bone regeneration and vascularization, embodying the practical application.