3D Printing of Tissue Engineering Scaffolds with Horizontal Pore and Composition Gradients

This work investigated a new 3D-printing methodology to prepare porous scaffolds containing horizontal pore and composition gradients. To achieve that, a multimaterial printing technology developed in our laboratory was adapted to incorporate pore gradients. Fibers were printed by welding segments with unique material compositions and fiber diameters. Particularly, we focused on the preparation of model composite poly(ε-caprolactone)-based scaffolds with radial gradients of particulate hydroxyapatite (HA) content (higher concentrations in the outer region of the scaffold) and porosity (higher in the inner region). The morphology of the scaffolds revealed that the methodology allowed the fabrication of discrete regions with compressive mechanical properties similar to human bone while maintaining structural integrity. HA distribution was homogeneous within individual regions and no particle aggregation was detected by microCT analysis and Alizarin red S staining. Finally, the incubation of the scaffolds in simulated body fluid resulted in the deposition of significantly higher amounts of calcium deposits in the regions of the scaffolds with higher HA content. This work provides a new tool for the preparation of porous scaffolds containing porosity and composition gradients for complex tissue engineering applications.