Visible Light Induced DLP-Printed Oxygen-Releasing TPMS Scaffolds Mitigate Early Hypoxia in Bone Defects

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Regenerative Medicine

Background:

• Oxygen deprivation is a major hurdle in bone defect regeneration, particularly before new blood vessels form.
• Current scaffolds often fail to adequately supply oxygen to the defect site.
• Effective oxygen delivery strategies are crucial for enhancing osteogenesis and vascularization.

Purpose of the Study:

• To develop and evaluate a novel 3D-printed hydrogel scaffold (COSnPPOD) for enhanced bone regeneration.
• To investigate the scaffold's ability to provide localized oxygen release and support osteogenic development.
• To assess the scaffold's biocompatibility, degradation, mechanical properties, and efficacy in promoting bone formation in vivo.

Main Methods:

• Development of COSnPPOD: A visible light 3D-printed hydrogel scaffold (gelatin methacrylate-poly(ethylene glycol) diacrylate) incorporating calcium peroxide (CaO2)-loaded hollow silica nanoparticles.
• In vitro characterization: Assessment of degradation kinetics, stiffness, protein adsorption, cell viability, and osteogenic gene expression using preosteoblasts.
• In vivo evaluation: Implantation of COSnPPOD scaffolds in a murine calvarial defect model to assess bone regeneration, collagen deposition, and vascularization via VEGF immunostaining.

Main Results:

• COSnPPOD scaffolds exhibited favorable degradation, tunable stiffness, and increased protein adsorption in vitro.
• The scaffold maintained preosteoblast viability and supported osteogenic gene expression, with a notable increase in Spp1 expression.
• In vivo studies showed significantly enhanced bone formation and collagen deposition in COSnPPOD treated defects compared to controls.
• Increased vascular endothelial growth factor (VEGF) staining indicated a proangiogenic response, with no observed systemic toxicity.

Conclusions:

• COSnPPOD is a promising 3D-printed hydrogel scaffold that effectively delivers oxygen to bone defects.
• The scaffold supports cell viability, osteogenesis, and promotes enhanced bone regeneration and vascularization in vivo.
• COSnPPOD represents a significant advancement in biomaterial design for addressing oxygen deprivation challenges in bone tissue engineering.