Synergistic
Amelioration
of Osseointegration and Osteoimmunomodulation
with a Microarc Oxidation-Treated Three-Dimensionally Printed Ti-24Nb-4Zr-8Sn
Scaffold via Surface Activity and Low Elastic Modulus
posted on 2024-01-11, 12:03authored byXinyue Yang, Lijun Wu, Cheng Li, Shujun Li, Wentao Hou, Yulin Hao, Yiping Lu, Lei Li
Biomaterial
scaffolds, including bone substitutes, have
evolved
from being primarily a biologically passive structural element to
one in which material properties such as surface topography and chemistry
actively direct bone regeneration by influencing stem cells and the
immune microenvironment. Ti-6Al-4V(Ti6Al4V) implants, with a significantly
higher elastic modulus than human bone, may lead to stress shielding,
necessitating improved stability at the bone–titanium alloy
implant interface. Ti-24Nb-4Zr-8Sn (Ti2448), a low elastic modulus
β-type titanium alloy devoid of potentially toxic elements,
was utilized in this study. We employed 3D printing technology to
fabricate a porous scaffold structure to further decrease the structural
stiffness of the implant to approximate that of cancellous bone. Microarc
oxidation (MAO) surface modification technology is then employed to
create a microporous structure and a hydrophilic oxide ceramic layer
on the surface and interior of the scaffold. In vitro studies demonstrated
that MAO treatment enhances the proliferation, adhesion, and osteogenesis
capabilities on the scaffold surface. The chemical composition of
the MAO-Ti2448 oxide layer is found to enhance the transcription and
expression of osteogenic genes in bone mesenchymal stem cells (BMSCs),
potentially related to the enrichment of Nb2O5 and SnO2 in the oxide layer. The MAO-Ti2448 scaffold,
with its synergistic surface activity and low stiffness, significantly
activates the anti-inflammatory macrophage phenotype, creating an
immune microenvironment that promotes the osteogenic differentiation
of BMSCs. In vivo experiments in a rabbit model demonstrated a significant
improvement in the quantity and quality of the newly formed bone trabeculae
within the scaffold under the contact osteogenesis pattern with a
matched elastic modulus. These trabeculae exhibit robust connections
to the external structure of the scaffold, accelerating the formation
of an interlocking structure between the bone and implant and providing
higher implantation stability. These findings suggest that the MAO-Ti2448
scaffold has significant potential as a bone defect repair material
by regulating osteoimmunomodulation and osteogenesis to enhance osseointegration.
This study demonstrates an optional strategy that combines the mechanism
of reducing the elastic modulus with surface modification treatment,
thereby extending the application scope of β-type titanium alloy.