Manufacturing of scaffolds with interconnected internal open porosity and surface roughness

Manufacturing of three-dimensional scaffolds with multiple levels of porosity are an advantage in tis-sue regeneration approaches to influence cell behavior. Three-dimensional scaffolds with surface rough-ness and intra-filament open porosity were successfully fabricated by additive manufacturing combined with chemical foaming and porogen leaching without the need of toxic solvents. The decomposition of sodium citrate, a chemical blowing agent, generated pores within the scaffold filament s, which were in-terconnected and opened to the external environment by leaching of a water-soluble sacrificial phase, as confirmed by micro-CT and buoyancy measurements. The additional porosity did not result in lower elas-tic modulus, but in higher strain at maximum load, i.e. scaffold ductility. Human mesenchymal stromal cells cultured for 24 h adhered in greater numbers on these scaffolds when compared to plain additive -manufactured ones, irrespectively of the scaffold pre-treatment method. Additionally, they showed a more spread and random morphology, which is known to influence cell fate. Cells cultured for a longer period exhibited enhanced metabolic activity while secreting higher osteogenic markers after 7 days in culture. Statement of significanceInspired by the function of hierarchical cellular structures in natural materials, this work elucidates the development of scaffolds with multiscale porosity by combining in-situ foaming and additive manufactur-ing, and successive porogen leaching. The resulting scaffolds displayed enhanced mechanical toughness and multiscale pore network interconnectivity, combined with early differentiation of adult mesenchymal stromal cells into the osteogenic lineage.(c) 2022 The Author(s). Published by Elsevier Ltd on behalf of Acta Materialia Inc. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

Automated summary

This study successfully fabricated three-dimensional scaffolds with surface roughness and intra-filament open porosity using additive manufacturing combined with chemical foaming and porogen leaching. The additional porosity did not affect the elastic modulus but increased the scaffold ductility. Cells adhered and exhibited enhanced metabolic activity and secretion of osteogenic markers on the scaffolds with multiple levels of porosity.