Rapid prototyped porous nickel-titanium scaffolds as bone substitutes.
While calcium phosphate-based ceramics are currently the most widely used materials in bone repair, they generally lack tensile strength for initial load bearing. Bulk titanium is the gold standard of metallic implant materials, but does not match the mechanical properties of the surrounding bone, potentially leading to problems of fixation and bone resorption. As an alternative, nickel-titanium alloys possess a unique combination of mechanical properties including a relatively low elastic modulus, pseudoelasticity, and high damping capacity, matching the properties of bone better than any other metallic material. With the ultimate goal of fabricating porous implants for spinal, orthopedic and dental applications, nickel-titanium substrates were fabricated by means of selective laser melting. The response of human mesenchymal stromal cells to the nickel-titanium substrates was compared to mesenchymal stromal cells cultured on clinically used titanium. Selective laser melted titanium as well as surface-treated nickel-titanium and titanium served as controls. Mesenchymal stromal cells had similar proliferation rates when cultured on selective laser melted nickel-titanium, clinically used titanium, or controls. Osteogenic differentiation was similar for mesenchymal stromal cells cultured on the selected materials, as indicated by similar gene expression levels of bone sialoprotein and osteocalcin. Mesenchymal stromal cells seeded and cultured on porous three-dimensional selective laser melted nickel-titanium scaffolds homogeneously colonized the scaffold, and following osteogenic induction, filled the scaffold's pore volume with extracellular matrix. The combination of bone-related mechanical properties of selective laser melted nickel-titanium with its cytocompatibility and support of osteogenic differentiation of mesenchymal stromal cells highlights its potential as a superior bone substitute as compared to clinically used titanium.
Departments of Biomedicine and Surgery, University Hospital Basel, Basel, Switzerland ; University of Applied Sciences Northwestern Switzerland, School of Life Sciences, Institute for Medical and Analytical Technologies, Gründenstrasse 40, 4132 Muttenz, Switzerland.
Waldemar
W
Hoffmann
University of Applied Sciences Northwestern Switzerland, School of Life Sciences, Institute for Medical and Analytical Technologies, Gründenstrasse 40, 4132 Muttenz, Switzerland ; Biomaterials Science Center, University of Basel, Basel, Switzerland.
Therese
T
Bormann
Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Zurich, Switzerland ; Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, Cagliari, Italy.
Antonella
A
Rossi
Biomaterials Science Center, University of Basel, Basel, Switzerland.
Bert
B
Müller
University of Applied Sciences Northwestern Switzerland, School of Life Sciences, Institute for Medical and Analytical Technologies, Gründenstrasse 40, 4132 Muttenz, Switzerland.
Ralf
R
Schumacher
Departments of Biomedicine and Surgery, University Hospital Basel, Basel, Switzerland.
Ivan
I
Martin
University of Applied Sciences Northwestern Switzerland, School of Life Sciences, Institute for Medical and Analytical Technologies, Gründenstrasse 40, 4132 Muttenz, Switzerland.
Michael
M
de Wild
Departments of Biomedicine and Surgery, University Hospital Basel, Basel, Switzerland.
David
D
Wendt
Bone tissue engineering; nickel–titanium; osteogenic differentiation; scaffold; selective laser melting