Dual-Channel Extrusion-Based 3D Printing of a Gradient Hydroxyapatite Hydrogel Scaffold with Spatial Curved...

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Bioprinting Technology

Background:

• Articular cartilage defects require advanced tissue engineering solutions.
• Mimicking native cartilage's compositional and architectural gradients is crucial for functional regeneration.
• Existing scaffolds often lack the precise control needed for complex, graded structures.

Purpose of the Study:

• To develop a 3D-bioprinted cartilage scaffold with a continuous hydroxyapatite (HA) gradient and curved architecture.
• To mimic the native calcified to non-calcified cartilage transition.
• To evaluate the scaffold's structural integrity, mechanical properties, and biological performance.

Main Methods:

• Utilized a dual-channel extrusion-based 3D bioprinting approach with dynamic bioink feeding rates.
• Achieved a continuous HA gradient decreasing from bottom to top.
• Integrated gradient deposition with multi-axis motion for curved geometry fabrication.
• Performed rheological, swelling, degradation, mechanical, and in vitro cytocompatibility/chondrogenicity assessments.

Main Results:

• Successfully fabricated curved scaffolds with precise, continuous HA gradients mimicking native cartilage.
• Demonstrated stable swelling and degradation, with enhanced compressive performance over step-gradient scaffolds.
• Bioinks exhibited favorable shear-thinning and recovery properties for printability.
• In vitro studies showed good cytocompatibility, supporting bone marrow mesenchymal stem cell (BMSC) adhesion, proliferation, and extracellular matrix synthesis.

Conclusions:

• Presented a controllable and versatile 3D bioprinting strategy for creating curved, compositionally graded cartilage scaffolds.
• The developed scaffold system is biosafety-confirmed and supports cartilage-related matrix production.
• This approach offers a promising platform for advanced biomimetic cartilage tissue engineering.