Evidence that nanoscale surface properties stimulate and guide various molecular and biological processes at the implant/tissue interface is fostering a new trend in designing implantable metals. ...Cutting-edge expertise and techniques drawn from widely separated fields, such as nanotechnology, materials engineering and biology, have been advantageously exploited to nanoengineer surfaces in ways that control and direct these processes in predictable manners. In this review, we present and discuss the state-of-the-art of nanotechnology-based approaches currently adopted to modify the surface of metals used for orthopedic and dental applications, and also briefly consider their use in the cardiovascular field. The effects of nanoengineered surfaces on various in vitro molecular and cellular events are firstly discussed. This review also provides an overview of in vivo and clinical studies with nanostructured metallic implants, and addresses the potential influence of nanotopography on biomechanical events at interfaces. Ultimately, the objective of this work is to give the readership a comprehensive picture of the current advances, future developments and challenges in the application of the infinitesimally small to biomedical surface science. We believe that an integrated understanding of the in vitro and particularly of the in vivo behavior is mandatory for the proper exploitation of nanostructured implantable metals and, indeed, of all biomaterials.
Bone formation around implants is influenced by surface geometry. Since cell/matrix/substrate interactions associated with cell signaling occur in the nanoscale dimension, we have evaluated the ...influence of nanotexturing of titanium-based surfaces on the expression of matrix proteins by cultured osteogenic cells at initial time points. Cells were obtained by enzymatic digestion of newborn rat calvaria and grown on titanium and titanium alloy discs with nanotextured or machined surfaces, and on glass coverslips for periods of 6
h, 1 day, and 3 days, under standard culture conditions. Cultures were processed for single or dual immunolabeling with monoclonal and/or polyclonal antibodies against bone sialoprotein (BSP), fibronectin (FN), osteopontin (OPN), type-I pro-collagen, or tubulin, followed by corresponding fluorophore-conjugated secondary antibodies. Some samples were processed for scanning electron microscope analysis of morphology and immunogold labeling. After 6
h, nanotextured surfaces exhibited up to a nine-fold increase in the proportion of cells with peripheral OPN labeling. At day 3, the proportion of OPN and BSP labeled cells was higher, and the intensity of immunoreactivity dramatically increased. No significant differences were observed in the expression pattern and the proportion of cells immunoreactive for FN or type-I pro-collagen. Our results demonstrate that nanotexturing of titanium-based surfaces upregulates the early expression of BSP and OPN in osteogenic cell cultures.
Aim
To evaluate the effects of AH Plus (Dentsply), Sealer 26 (Dentsply), and Sealer Plus BC (Produtos Médicos e Odontológicos) on cytotoxicity and inflammation in macrophage cultures exposed to ...bacterial lipopolysaccharide (LPS).
Methodology
After initial setting, the sealers were conditioned with serum‐free culture medium for 24 h (1 ml/cm2). Macrophages from the RAW 264.7 strain were exposed to sealer extracts in a 1:16 ratio in a culture medium with or without LPS. Cell morphology, viability, mitochondrial activity, oxidative stress and gene expression of interleukin 1β (IL‐1β) and tumour necrosis factor‐alpha (TNF‐α) were evaluated. Data on mitochondrial activity, oxidative stress and TNF‐α were analysed using a two‐way analysis of variance (anova) test, followed by the Student–Newman–Keuls post‐test. IL‐1β data were analysed using one‐way anova, followed by SNK, and the t‐test was used for intragroup comparison. The significance level was set at 5%.
Results
In the absence of LPS, only AH Plus and Sealer 26 showed a reduction in cell density, while in the presence of LPS, Sealer 26 had the lowest density compared to the other groups. In terms of mitochondrial activity, at 24 and 48 h, Sealer Plus BC had significantly higher mean values than Sealer 26 and AH Plus (p < .05). Sealer 26 exhibited the lowest levels of oxidative stress and IL‐1β and TNF‐α expression, regardless of the presence of LPS (p < .05).
Conclusions
Although all sealers interfere with the response of macrophages to LPS, contact with epoxy resin‐based sealers can impair cell activity in vitro, while bioceramic sealer seems to favour the inflammatory functions of these cells.
In the field of regenerative medicine, nanoscale physical cuing is clearly becoming a compelling determinant of cell behavior. Developing effective methods for making nanostructured surfaces with ...well-defined physicochemical properties is thus mandatory for the rational design of functional biomaterials. Here, we demonstrate the versatility of simple chemical oxidative patterning to create unique nanotopographical surfaces that influence the behavior of various cell types, modulate the expression of key determinants of cell activity, and offer the potential of harnessing the power of stem cells. These findings promise to lead to a new generation of improved metal implants with intelligent surfaces that can control biological response at the site of healing.
Highly porous zirconia (ZrO2) scaffolds fabricated by the replication method were coated with fluorapatite (FA). The FA coating was obtained by dipping the ZrO2 scaffolds into stabilized aqueous FA ...slips having different viscosity values (≤5.0 mPa.s). The influence of the FA slip viscosity and the immersion time on the reduction in the scaffold porosity and microstructure of the coated scaffolds were investigated. Cell spreading and survival of bone marrow‐derived stromal cells (BMSC) and pre‐osteoblastic MC3T3‐E1 cells on the uncoated and coated scaffolds were examined using fluorescence and SEM microscopy, and MTT assay.The FA slip with the lowest viscosity value did not lead to a continuous film along the strut network and the macropores remained uncoated. The slips with the highest viscosity value produced a partial blocking of macropores. The porous structure obtained after coating with slips of 2.2 mPa.s viscosity for 2 seconds exhibited a low reduction in porosity and pore size (400‐420 μm), due to the formation of the FA layer, and a continuous film distributed along the strut surfaces. Morphology, spreading, and survival of BMSC and MC3T3‐E1 cells over a 7‐day culture period evidenced good biocompatibility of FA‐coated ZrO2 scaffolds processed by dip coating.
In the course of attempting to define the bone “secretome” using a signal‐trap screening approach, we identified a gene encoding a small membrane protein novel to osteoblasts. Although previously ...identified in silico as ifitm5, no localization or functional studies had been undertaken on this gene. We characterized the expression patterns and localization of this gene in vitro and in vivo and assessed its role in matrix mineralization in vitro. The bone specificity and shown role in mineralization led us to rename the gene bone restricted ifitm‐like protein (Bril). Bril encodes a 14.8‐kDa 134 amino acid protein with two transmembrane domains. Northern blot analysis showed bone‐specific expression with no expression in other embryonic or adult tissues. In situ hybridization and immunohistochemistry in mouse embryos showed expression localized on the developing bone. Screening of cell lines showed Bril expression to be highest in osteoblasts, associated with the onset of matrix maturation/mineralization, suggesting a role in bone formation. Functional evidence of a role in mineralization was shown by adenovirus‐mediated Bril overexpression and lentivirus‐mediated Bril shRNA knockdown in vitro. Elevated Bril resulted in dose‐dependent increases in mineralization in UMR106 and rat primary osteoblasts. Conversely, knockdown of Bril in MC3T3 osteoblasts resulted in reduced mineralization. Thus, we identified Bril as a novel osteoblast protein and showed a role in mineralization, possibly identifying a new regulatory pathway in bone formation.
A quantity of 3 mol% yttria‐partially stabilized zirconia (Y‐TZP) with 10.5 and 19.9 vol% 64S bioglass compacts was sintered at different temperatures up to 1500°C. The influence of 64S glass ...addition on the sintering kinetic, flexural strength, and osteoblast cell response of Y‐TZP ceramics was investigated. The addition of 64S glass increased the initial sintering rate through the decrease in the activation energy and the increase on the order of diffusion with respect to those previously reported for Y‐TZP. Y‐TZP at 1500°C exhibited the highest flexural strength. Within Y‐TZP ceramics with 64S additions, a maximum flexural strength occurred for 10.5 vol% 64S at 1400°C, its flexural strength was able to approach that of Y‐TZP at 1500°C. The polished sintered surfaces became rougher as the 64S content increased. Cell viability experiments on the less nanoroughness Y‐TZP and Y‐TZP with 10.5 vol% 64S surfaces revealed their good biocompatibility; on the contrary, the high level of nanoroughness of Y‐TZP with 19.9 vol% 64S significantly reduced cell survival. However, the matrix mineralization was not adversely affected by the surface roughness; larger amounts of calcium phosphate phases on Y‐TZP‐19.9 vol% 64S surfaces appeared to promote the osteogenic potential of UMR‐106 cells.
Y‐TZP containing Ca2P2O7 are promising bioceramics with potential applications in dental implants and dentistry. These ceramics were developed by the introduction of a refractory sol‐gel derived ...CaO‐P2O5‐SiO2 bioglass into Y‐TZP; Ca2P2O7, and ZrSiO4 phases were formed in situ after sintering. The aging process of Y‐TZP with different glass additions was studied. The effect of glass addition on the flexural strength and osteoblastic cell response of non‐aged and aged Y‐TZP was investigated. Y‐TZP exhibited the most pronounced tetragonal (t) to monoclinic (m) transformation of zirconia (ZrO2) during aging; the addition of glass contents between 5 and 20 vol% improved the aging resistant of Y‐TZP. Y‐TZP flexural strength markedly decreased with increasing aging time; in contrast, the ceramics with glass did not alter their flexural strength upon aging. An increase in the Ca2P2O7 content with increasing glass up to 10 vol%, promoted both the cell viability and the osteogenic differentiation of UMR‐106 cells on non‐aged and aged samples. The high micro‐roughness of Y‐TZP with 20 vol% glass after aging, limited the proliferation and the osteogenic potential of the cultures. Y‐TZP with 10 vol% glass had the best combination of properties in terms of flexural strength and osteoblast cell response.
Calcium aluminate cement (CAC) has been highlighted as a promising alternative for endodontic use aiming at periapical tissue repair. However, its effects on dental pulp cells have been poorly ...explored.
This study assessed the impact of calcium chloride (CaCl2) and bismuth oxide (Bi2O3) or zinc oxide (ZnO) additives on odontoblast cell response to CAC.
MDPC-23 cells were exposed for up to 14 d: 1) CAC with 2.8% CaCl2 and 25% ZnO (CACz); 2) CAC with 2.8% CaCl2 and 25% Bi2O3 (CACb); 3) CAC with 10% CaCl2 and 25% Bi2O3 (CACb+); or 4) mineral trioxide aggregate (MTA), placed on inserts. Non-exposed cultures served as control. Cell morphology, cell viability, gene expression of alkaline phosphatase (ALP), bone sialoprotein (BSP), and dentin matrix protein 1 (DMP-1), ALP activity, and extracellular matrix mineralization were evaluated. Data were compared using ANOVA (α=5%).
Lower cell density was detected only for MTA and CACb+ compared with Control, with areas showing reduced cell spreading. Cell viability was similar among groups at days one and three (p>0.05). CACb+ and MTA showed the lowest cell viability values at day seven (p>0.05). CACb and CACb+ promoted higher ALP and BSP expression compared with CACz (p<0.05); despite that, all cements supported ALP activity. Matrix mineralization were enhanced in CACb+ and MTA.
In conclusion, CAC with Bi2O3, but not with ZnO, supported the expression of odontoblastic phenotype, but only the composition with 10% CaCl2 promoted mineralized matrix formation, rendering it suitable for dentin-pulp complex repair.
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