In situ engineered silicon-magnesium implants orchestrate sequential immunomodulation, angiogenesis, and osteogenesis...

Area of Science:

• Biomaterials Science
• Orthopedic Engineering
• Regenerative Medicine

Background:

• Magnesium (Mg) shows promise for bone implants due to mechanical properties and biodegradability.
• Rapid Mg corrosion leads to inflammation and limits clinical use.
• Existing Mg implants require strategies to manage degradation byproducts and enhance tissue integration.

Purpose of the Study:

• To develop a multifunctional Mg-based implant (Mg/Mg2SiO4/PDA - MSP) for enhanced bone regeneration.
• To engineer a surface that orchestrates sequential biological responses: anti-infection, immunomodulation, vascularization, and osteogenesis.
• To address the limitations of pure Mg implants by controlling degradation and promoting a regenerative microenvironment.

Main Methods:

• Fabrication of a multilayered Mg implant with an in situ Mg2SiO4 interlayer and polydopamine (PDA) functionalization.
• Assessment of antibacterial activity, immunomodulatory effects (macrophage polarization), and pro-angiogenic properties.
• In vitro cytocompatibility studies with rat adipose-derived stem cells (rADSCs) and in vivo evaluation of new bone formation and osseointegration.

Main Results:

• The MSP implant demonstrated effective antibacterial activity, with bacterial survival rates below 20%.
• PDA-mediated immunomodulation promoted M2 macrophage polarization and suppressed pro-inflammatory cytokines.
• Controlled release of Mg2+ and Si4+ ions, synergized with PDA, enhanced angiogenesis and osteogenesis, leading to a 73% increase in bone volume fraction (BV/TV) compared to Mg.
• The implant exhibited potent antibacterial activity, immunoregulatory capacity, antioxidative properties, and excellent cytocompatibility.

Conclusions:

• The developed Mg/Mg2SiO4/PDA implant offers a multifunctional platform for bone regeneration.
• The sequential, time-windowed effects of the multilayered design enable controlled biological responses, from initial anti-infection to late-stage bone formation.
• This surface engineering strategy presents a promising approach for creating advanced Mg-based implants that overcome degradation challenges and promote healing in inflammatory conditions.