Hierarchical porosity inherited by natural sources affects the mechanical and biological behaviour of bone scaffolds

A 3-D porous apatite scaffold (B-HA), recently obtained through biomorphic transformation of a natural wood, isinvestigated on its multi-scale porous structure determining superior biological and mechanical behaviour. B-HAshows a hierarchically organized architecture with wide aligned channels interconnected with smaller tubules,thus recapitulating in detail the lymphatic network of the original wood template. As induced by its biomimeticarchitecture, B-HA displays values of tensile/compressive strengths and stiffness, higher than values usuallymeasured in sintered ceramics with isotropic porosity. Furthermore, B-HA shows uncommon toughness for apure ceramic body, plus a tensile/compressive-strength ratio higher than one, so that the material occupies azone in the Ashby map where ceramics are normally absent. From biological viewpoint, cell co-culture tests inbioreactor are shown to report encouraging results in enhancing the complex tissue regeneration process, thusmaking B-HA promising as a scaffold able to promote bone regeneration, particularly for large bone defects.