7 research outputs found
Facet-Specific Mineralization Behavior of Nano-CaP on Anatase Polyhedral Microcrystals
Biomimetic mineralization
of nanocalcium phosphate (CaP) on metal
oxide surfaces has gained great interest because of their relevance
to osseointegration performance of implant materials. However, precisely
controlling the nucleation behavior of mineralized nano-CaP on metal
oxide at selective sites still remains a challenge. Here, we demonstrate
a phenomenon on facet-specific mineralization on anatase TiO<sub>2</sub> polyhedral microcrystals organized by two facets of {101} and {001}
in complete cell culture medium: nano-CaP covers up {101} facets,
while there are a few on {001} facets. The comparative experimental
results indicate that the preadsorbed fetal bovine serum (FBS) protein
on {001} facets might play a barrier role in preventing sequential
nucleation of nano-CaP. This work thus provides insight into the understanding
of mineralization on metal oxides, and a way to control the mineralization
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 TiO<sub>2</sub> 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. <i>In vivo</i> 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
Light-Induced Cell Alignment and Harvest for Anisotropic Cell Sheet Technology
Well-organized
orientation of cells and anisotropic extracellular matrix (ECM) are
crucial in engineering biomimetic tissues, such as muscles, arteries,
and nervous system, and so on. This strategy, however, is only beginning
to be explored. Here, we demonstrated a light-induced cell alignment
and harvest for anisotropic cell sheets (ACS) technology using light-responsive
TiO<sub>2</sub> nanodots film (TNF) and photo-cross-linkable gelatin
methacrylate (GelMA). Cell initial behaviors on TNF might be controlled
by micropatterns of light-induced distinct surface hydroxyl features,
owing to a sensing mechanism of myosin II-driven retraction of lamellipodia.
Further light treatment allowed ACS detachment from TNF surface while
simultaneously solidified the GelMA, realizing the automatic transference
of ACS. Moreover, two detached ACS were successfully stacked into
a 3D bilayer construct with controllable orientation of individual
layer and maintained cell alignment for more than 7 days. Interestingly,
the anisotropic HFF-1 cell sheets could further induce the HUVECs
to form anisotropic capillary-like networks via upregulating VEGFA
and ANGPT1 and producing anisotropic ECM. This developed integrated-functional
ACS technology therefore provides a novel route to produce complex
tissue constructs with well-defined orientations and may have a profound
impact on regenerative medicine
Surface Atomic Structure Directs the Fate of Human Mesenchymal Stem Cells
Stem
cells in contact with materials are able to sense their surface features,
integrate extracellular matrix (ECM) protein cues through a signal
transduction pathway, and ultimately direct cell fate decisions. However,
discovering the interdisciplinary mechanisms of how stem cells respond
to inherent material surface features still remains a challenge due
to the complex, multicomponent signaling milieu present in the ECM
environment. Here, we demonstrate that the fate of human mesenchymal
stem cells (hMSCs) can be regulated by the inherent physical cue of
the material surface down to atomic-scale features. hMSCs on a TiO-terminated
SrTiO<sub>3</sub> {110} substrate tend to differentiate into specific
lineage cells (osteoblast, chondrocyte, adipocyte), whereas on a TiO<sub>2</sub>-terminated SrTiO<sub>3</sub> {100} substrate they are prone
to maintain pluripotency. The experimental observations and molecular
dynamics simulations indicate that the distinct conformations of the
initially adsorbed serum albumin and fibronectin proteins activate
the integrin–focal adhesion cytoskeleton actin transduction
pathway and, subsequently, direct the gene and protein expressions
of hMSCs. Moreover, we demonstrate that the initial protein adsorption
behaviors are dependent on the distinct hydroxyl groups originating
from different surface atomic structures as well as the work functions.
This work, therefore, provides new insights into the fundamental understanding
of cell–material interactions and will have a profound impact
on further designing materials to direct the stem cell fate
Harnessing Cell Dynamic Responses on Magnetoelectric Nanocomposite Films to Promote Osteogenic Differentiation
The
binding of cell integrins to proteins adsorbed on the material
surface is a highly dynamic process critical for guiding cellular
responses. However, temporal dynamic regulation of adsorbed proteins
to meet the spatial conformation requirement of integrins for a certain
cellular response remains a great challenge. Here, an active CoFe<sub>2</sub>O<sub>4</sub>/polyÂ(vinylidene fluoride-trifluoroethylene)
nanocomposite film, which was demonstrated to be an obvious surface
potential variation (Δ<i>V</i> ≈ 93 mV) in
response to the applied magnetic field intensity (0–3000 Oe),
was designed to harness the dynamic binding of integrin-adsorbed proteins
by in situ controlling of the conformation of adsorbed proteins. Experimental
investigation and molecular dynamics simulation confirmed the surface
potential-induced conformational change in the adsorbed proteins.
Cells cultured on nanocomposite films indicated that cellular responses
in different time periods (adhesion, proliferation, and differentiation)
required distinct magnetic field intensity, and synthetically programming
the preferred magnetic field intensity of each time period could further
enhance the osteogenic differentiation through the FAK/ERK signaling
pathway. This work therefore provides a distinct concept that dynamically
controllable modulation of the material surface property fitting the
binding requirement of different cell time periods would be more conducive
to achieving the desired osteogenic differentiation
Controlled Release of Naringin in Metal-Organic Framework-Loaded Mineralized Collagen Coating to Simultaneously Enhance Osseointegration and Antibacterial Activity
Two
important goals in orthopedic implant research are to promote osseointegration
and prevent infection. However, much previous effort has been focused
on the design of coatings to either enhance osseointegration while
ignoring antibacterial activity or vice versa, to prevent infection
while ignoring bone integration. Here, we designed a multifunctional
mineralized collagen coating on titanium with the aid of metal-organic
framework (MOF) nanocrystals to control the release of naringin, a
Chinese herbal medicine that could promote osseointegration and prevent
bacterial infection. The attachment, proliferation, osteogenic differentiation,
and mineralization of mesenchymal stem cells on the coating were significantly
enhanced. Meanwhile, the antibacterial abilities against Staphylococcus aureus were also promoted. Furthermore,
release kinetics analysis indicated that the synergistic effect of
a primary burst release stage and secondary slow release stage played
a critical role in the performance and could be controlled by the
relative concentrations of MOF and naringin. This work thus provides
a novel strategy to engineer multifunctional orthopedic coatings that
can enhance osseointegration and simultaneously inhibit microbial
cell growth
Light-Induced Cell Alignment and Harvest for Anisotropic Cell Sheet Technology
Well-organized
orientation of cells and anisotropic extracellular matrix (ECM) are
crucial in engineering biomimetic tissues, such as muscles, arteries,
and nervous system, and so on. This strategy, however, is only beginning
to be explored. Here, we demonstrated a light-induced cell alignment
and harvest for anisotropic cell sheets (ACS) technology using light-responsive
TiO<sub>2</sub> nanodots film (TNF) and photo-cross-linkable gelatin
methacrylate (GelMA). Cell initial behaviors on TNF might be controlled
by micropatterns of light-induced distinct surface hydroxyl features,
owing to a sensing mechanism of myosin II-driven retraction of lamellipodia.
Further light treatment allowed ACS detachment from TNF surface while
simultaneously solidified the GelMA, realizing the automatic transference
of ACS. Moreover, two detached ACS were successfully stacked into
a 3D bilayer construct with controllable orientation of individual
layer and maintained cell alignment for more than 7 days. Interestingly,
the anisotropic HFF-1 cell sheets could further induce the HUVECs
to form anisotropic capillary-like networks via upregulating VEGFA
and ANGPT1 and producing anisotropic ECM. This developed integrated-functional
ACS technology therefore provides a novel route to produce complex
tissue constructs with well-defined orientations and may have a profound
impact on regenerative medicine