3D Bioprinting and Near-Field Electrospinning Composite Scaffolds for the Bone-Ligament Interface

3D bioprinting is an additive manufacturing technique that can utilize a range of bioactive materials to construct specific architectures that mimic native tissue. Near-field electrospinning (NFE) offers precise alignment control to create non-woven mats with high tensile strengths. We built a custom E-spin printer that enables layer-by-layer alternating deposition between 3D bioprinting and NFE to create composite scaffolds for the bone-ligament interface. This complex region is difficult to simulate due to its functionally graded mechanical and biochemical properties. We created NFE poly(caprolactone) highly aligned micro-fibers which formed collagen fibril-like bundles. Poly(ethylene glycol) diacrylate with decellularized bone was encased in the PCL fibers to create bony ligament support structures in a composite scaffold. Cytotoxicity of all materials was determined through a Live/Dead assay (Thermo Fisher) with NIH/3T3 cells. The materials and the composite scaffold were seeded with 3T3 cells and cultured for three days before undergoing an immunocytochemistry staining (ICC) to assess cell adhesion and spreading. Increased adhesion and spreading on decellularized bone scaffolds along with cell elongation in the direction of the fibers suggests the ability of the scaffold to encourage osteoblastic differentiation and ligamentous tissue formation, though a longitudinal study is still underway. Mechanical results suggest that the composite scaffolds have increased compressive strength over PEGDA alone as the PCL fibers constrict horizontal elongation, thus yielding a higher compressive modulus. The PCL fibers demonstrated a tensile strength approaching native ligament (3.96 ± 1.10 MPa), which shows promise as the ligament phase of the scaffold. The E-spin printer’s versatility with materials of disparate viscosities enabled the layer-by-layer fabrication of composite (PCL/PEGDA+bone) scaffolds that begin to mimic the complex nature of the bone-ligament interface