3D Plotted Biphasic Bone Scaffolds for Growth Factor Delivery: Biological Characterization In Vitro and In Vivo.

Area of Science:

• Biomaterials Engineering
• Regenerative Medicine
• Tissue Engineering

Background:

• 3D bioprinting allows precise integration of biological components into scaffolds.
• Scaffolds offer advantages in loading efficiency and controlled release/spatial positioning of bioactive factors.
• Calcium phosphate cement (CPC) and alginate/gellan gum (AlgGG) hydrogels are promising biomaterials for bone regeneration.

Purpose of the Study:

• To investigate the biological response of a biphasic scaffold fabricated via 3D bioprinting for bone regeneration.
• To evaluate the osteogenic potential and angiogenic effects of the scaffold in vitro and in vivo.
• To assess the efficacy of sustained vascular endothelial growth factor (VEGF) release for enhanced bone defect repair.

Main Methods:

• Fabrication of a biphasic scaffold using extrusion-based 3D multichannel plotting of CPC and VEGF-laden AlgGG hydrogel.
• In vitro assessment of rat mesenchymal stromal cell adhesion, growth, and osteogenic differentiation.
• In vitro evaluation of VEGF release kinetics and its effect on endothelial cell proliferation and angiogenesis.
• In vivo implantation of the scaffold into a rat femoral bone defect model to assess bone regeneration and vascularization.

Main Results:

• Mesenchymal stromal cells adhered, grew, and differentiated toward osteoblasts on both CPC and AlgGG components.
• Sustained VEGF release from the hydrogel maintained its biological activity, stimulating endothelial cell proliferation and angiogenesis in vitro.
• In vivo, the biphasic scaffold facilitated significant bone regeneration within the defect over 12 weeks.
• The CPC component demonstrated excellent osteoconductivity, while VEGF release enhanced vascularization of the defect area.

Conclusions:

• 3D bioprinting of biphasic scaffolds offers a promising strategy for bone regeneration.
• The combination of osteoconductive CPC and angiogenic VEGF-loaded hydrogel promotes effective bone defect repair.
• This approach contributes to developing novel therapeutic concepts for enhanced bone regeneration through advanced bioprinting techniques.