Titanium
and its alloys have been widely used as bone implants,
but for reduced treatment span, improvements are urgently needed to
achieve faster and better osteointegration. In this study, we found
that miR-132-3p inhibited bone-marrow-derived stem cell (BMSC) osteogenic
differentiation via targeting BMP2, and that inhibiting miR-132-3p
could significantly improve the osteogenic capability of BMSCs. Moreover,
we fabricated a biocompatible selenomethionine (SEMET)-modified polyethylene
glycol (PEG)/polyethylenimine (PEI) nanoparticle (SeNP) cross-linked
with 0.2% gelatin solutions and delivered miR-132-3p inhibitor to
biofunctionalize alkali heat-treated titanium implants, resulting
in the development of a novel coating for reverse transfection. The
biological performances of PEG/PEI/miR-132-3p inhibitor and SeNP/miR-132-3p
inhibitor-biofunctionalized titanium were compared. The biological
effects, including cell viability, cytotoxicity, adhesion, cellular
uptake, and osteogenic capacity of SeNP/miR-132-3p inhibitor-biofunctionalized
titanium implants, were then assessed. Results showed that SeNPs presented
appropriate morphology, diameter, and positive zeta potential for
efficient gene delivery. The transfection efficiency of the SeNP/miR-132-3p
inhibitor was comparable to that of the PEG/PEI/miR-132-3p inhibitor,
but the former induced less reactive oxygen species (ROS) production
and lower apoptosis rates. Confocal laser scanning microscopy (CLSM)
demonstrated that SeNP/miR-132-3p inhibitor nanoparticles released
from the titanium surfaces and were taken up by adherent BMSCs. In
addition, the release profile showed that transfection could obtain
a long-lasting silencing effect for more than 2 weeks. The cell viability,
cytotoxicity, and cell spreading of SeNP/miRNA-132-3p inhibitor-biofunctionalized
titanium were comparable with those of untreated titanium and the
SeNP/miRNA-132-3p inhibitor negative control (NC)-biofunctionalized
titanium but resulted in higher ALP activity and osteogenic gene expression
levels. In vivo animal studies further certified that SeNP/miRNA-132-3p
inhibitor nanoparticles from titanium surfaces promoted osteointegration,
which was revealed by microcomputed tomography (micro-CT) and histological
observations. Taken together, these findings suggested that selenomethionine-modified
PEI-based nanoparticles could achieve better biocompatibility. Moreover,
titanium implants biofunctionalized by SeNP/miRNA-132-3p inhibitor
nanoparticles might have significant clinical potential for more effective
osteointegration.