Single-Step Extrusion Printing of Microgrooved Annulus Fibrosus Scaffolds via Patterned Nozzles

Area of Science:

• Biomaterials Engineering
• Tissue Engineering
• Regenerative Medicine

Background:

• Intervertebral disk pathology, such as herniation and degeneration, is a primary cause of chronic low back pain.
• Current surgical treatments for disk pathology often result in residual annulus fibrosus (AF) defects, leading to reherniation and further degeneration.
• Existing biomaterial scaffolds struggle to replicate the complex, hierarchical, angle-ply architecture of the native AF.

Purpose of the Study:

• To develop a novel, single-step 3D-printing approach for fabricating polycaprolactone (PCL) scaffolds with microscale surface grooves.
• To investigate the ability of these scaffolds to mimic the AF's angle-ply structure and promote organized cellular infiltration and extracellular matrix deposition.
• To explore the influence of topographical cues and growth factor supplementation on cell behavior and gene expression for potential AF regeneration.

Main Methods:

• Utilized an extrusion-based 3D-printing technique with custom patterned nozzles to create PCL scaffolds featuring uniaxial concave microgrooves.
• Cultured human bone marrow-derived mesenchymal stem cells on the patterned scaffolds to assess cellular alignment and organization.
• Performed gene expression analysis to evaluate the impact of topographical cues and TGF-β3 supplementation on cellular behavior and matrix production.

Main Results:

• The 3D-printing method successfully fabricated PCL scaffolds with aligned microscale surface grooves, mimicking the angle-ply architecture of the AF.
• Mesenchymal stem cells cultured on the patterned scaffolds exhibited longitudinal alignment within the microgrooves, forming organized arrays and guiding extracellular matrix deposition.
• Topographical cues primarily influenced cellular organization without significantly altering gene expression profiles, while TGF-β3 upregulated specific outer AF markers. TAGLN expression increased on patterned scaffolds without TGF-β3, suggesting a link to microgroove-guided organization.

Conclusions:

• A novel single-step extrusion-printing approach enables scalable fabrication of multilamellar, angle-ply scaffolds with concave microgrooves.
• These scaffolds effectively induce aligned cellular organization, mimicking native tissue structures and showing promise for annulus fibrosus repair.
• The findings support the potential application of these scaffolds in regenerative strategies for the annulus fibrosus and for mechanobiological studies of anisotropic musculoskeletal tissues.