Osteoinduction by Foamed and 3D-Printed Calcium Phosphate Scaffolds: Effect of Nanostructure and Pore Architecture

• Published in: ACS applied materials & interfaces Vol. 9; no. 48; pp. 41722 - 41736
• Main Authors: Barba, Albert, Diez-Escudero, Anna, Maazouz, Yassine, Rappe, Katrin, Espanol, Montserrat, Montufar, Edgar B, Bonany, Mar, Sadowska, Joanna M, Guillem-Marti, Jordi, Öhman-Mägi, Caroline, Persson, Cecilia, Manzanares, Maria-Cristina, Franch, Jordi, Ginebra, Maria-Pau
• Format: Journal Article Publication
• Language: English
• Published: United States American Chemical Society 06-12-2017
• Subjects: 3D-printing; Biomedical materials; Calcium phosphate; Engineering Science with specialization in Materials Science; Enginyeria de teixits; Enginyeria dels materials; foaming; Fosfat de calci; Impressió 3D; Materials biomèdics; nanostructure; osteoinduction; Teknisk fysik med inriktning mot materialvetenskap; Three-dimensional printing; Tissue engineering; Àrees temàtiques de la UPC; nanostructure; foaming; 3D-printing; calcium phosphate; osteoinduction
• ISSN: 1944-8244; 1944-8252; 1944-8252
• DOI: 10.1021/acsami.7b14175

Some biomaterials are osteoinductive, that is, they are able to trigger the osteogenic process by inducing the differentiation of mesenchymal stem cells to the osteogenic lineage. Although the underlying mechanism is still unclear, microporosity and specific surface area (SSA) have been identified as critical factors in material-associated osteoinduction. However, only sintered ceramics, which have a limited range of porosities and SSA, have been analyzed so far. In this work, we were able to extend these ranges to the nanoscale, through the foaming and 3D-printing of biomimetic calcium phosphates, thereby obtaining scaffolds with controlled micro- and nanoporosity and with tailored macropore architectures. Calcium-deficient hydroxyapatite (CDHA) scaffolds were evaluated after 6 and 12 weeks in an ectopic-implantation canine model and compared with two sintered ceramics, biphasic calcium phosphate and β-tricalcium phosphate. Only foams with spherical, concave macropores and not 3D-printed scaffolds with convex, prismatic macropores induced significant ectopic bone formation. Among them, biomimetic nanostructured CDHA produced the highest incidence of ectopic bone and accelerated bone formation when compared with conventional microstructured sintered calcium phosphates with the same macropore architecture. Moreover, they exhibited different bone formation patterns; in CDHA foams, the new ectopic bone progressively replaced the scaffold, whereas in sintered biphasic calcium phosphate scaffolds, bone was deposited on the surface of the material, progressively filling the pore space. In conclusion, this study demonstrates that the high reactivity of nanostructured biomimetic CDHA combined with a spherical, concave macroporosity allows the pushing of the osteoinduction potential beyond the limits of microstructured calcium phosphate ceramics.