Enhanced Osteointegration of Hierarchical Structured 3D-Printed Titanium Implants

Three-dimensional
(3D) printing technology has been widely used
to fabricate of various titanium and its alloy implants. However,
engineering the 3D printing nanoscaled feature to realize a hierarchical
micronano structured surface topography still remains a challenge.
On one hand, enhanced bioactivity is always expected on micronano-hybrid
biomimetic topography; on the other hand, a typical functional protein
in extracellular matrix (ECM) is nanoscaled; therefore, nanoscaled
features might affect its binding to specific receptor and subsequent
cell response. Here, we engineered a novel hierarchical structure
with microparticles and rutile TiO2 nanorods topography
that fabricated by 3D printing of pure titanium followed by a hydrothermal
process. Although there was no difference on the microscaled feature
before/after nanonization, cellular behaviors including adhesion,
proliferation, and osteogenic differentiation of mesenchymal stem
cells (MSCs) were significantly upregulated on the hierarchical micronano
structured topography. Moreover, we demonstrated that the distinct
conformation of the initially fibronectin proteins adsorbed on nanorods
was more beneficial to cellular adhesion. In vivo test in a rabbit femur model also demonstrated the favorable for
new bone formation on the novel hierarchical micronano structured
implant–bone interface. These results therefore suggest that
the hierarchical micronano structured topography might be a promising
surface feature for the new generation of bone implants.