Viability Of Osteoblast-like Cells Research Articles

Development of Super-Paramagnetic Iron Oxide Nanoparticle-Coated Melt Electrowritten Scaffolds for Biomedical Applications.

Polycaprolactone (PCL) is usually the material chosen for melt electrowriting (MEW) due to its biocompatibility, mechanical strength, and melt processability. This work first investigates the effect of different processing parameters to obtain optimum PCL-MEW scaffolds. Secondly, to increase PCL`s hydrophilicity and cell affinity, and to enable coating with superparamagnetic iron oxide nanoparticles (SPIONs) and silica-coated-SPIONs (Si-SPIONs), the scaffolds are modified with alkaline surface treatment. Finally, SPIONs and Si-SPIONs are successfully coated on MEW scaffolds. Results show that reproducible scaffolds are fabricated. Additionally, the alkaline treatment does not change the three-dimensionalmorphology of scaffolds while reducing fiber diameter. Furthermore, SEM images and ATR-FTIR results confirmed that SPIONs and Si-SPIONs-were coated on scaffolds. A cytocompatibility assay showed a non-toxic effect on MG-63 osteoblast-like cells in all scaffolds. Additionally, higher MC3T3-E1 pre-osteoblastic cell adhesion efficiency and proliferation are achieved for the alkaline-treated scaffolds and SPIONs/Si-SPIONs-coated scaffolds. All samples demonstrated the ability to generate heat, useful for hyperthermia-treatment, when subjected to an alternating magnetic field. Overall, the findings suggest that the strategy of coating PCL-MEW scaffolds with SPIONs/Si-SPIONs has the potential to improve scaffold performance for biomedical applications, especially for producing magnetically responsive MEW scaffolds.

Design and Development of Tantalum and Strontium Ion Doped Hydroxyapatite Composite Coating on Titanium Substrate: Structural and Human Osteoblast-like Cell Viability Studies.

In order to reduce the loosening of dental implants, surface modification with hydroxyapatite (HA) coating has shown promising results. Therefore, in this present study, the sol-gel technique has been employed to form a tantalum and strontium ion-doped hybrid HA layer coating onto the titanium (Ti)-alloy substrate. In this study, the surface modification was completed by using 3% tantalum pent oxide (Ta2O5), 3% strontium (Sr), and a combination of 1.5% Ta2O5 and 1.5% Sr as additives, along with HA gel by spin coating technique. These additives played a prominent role in producing a porous structure layer coating and further cell growth. The MG63 cell culture assay results indicated that due to the incorporation of strontium ions along with tantalum embedded in HA, cell proliferation increased significantly after a 48 h study. Therefore, the present results, including microstructure, crystal structure, binding energy, and cell proliferation, showed that the additives 1.5% Ta2O5 and 1.5% Sr embedded in HA on the Ti-substrate had an optimized porous coating structure, which will enhance bone in-growth in surface-modified Ti-implants. This material had a proper porous morphology with a roughness profile, which may be suitable for tissue in-growth between a surface-modified textured implant and bone interface and could be applicable for dental implants.

Evaluation of indocyanine-mediated photodynamic therapy cytotoxicity in human osteoblast-like cells: an in vitro study.

Antimicrobial photodynamic therapy (aPDT) is an adjunctive non-invasive procedure for the management of periodontal tissue infection and deep periodontal pocket decontamination. However, the effects of this procedure on periodontal cells like osteoblasts that play a role in periodontal tissue repair and regeneration is not yet clear.

Monetite vs. Brushite: Different Influences on Bone Cell Response Modulated by Strontium Functionalization.

Monetite and brushite are regarded with increasing interest for the preparation of biomaterials for applications in the musculoskeletal system. Herein, we investigated the influence of strontium substitution in the structures of these two phosphates on bone cell response. To achieve this aim, co-cultures of human primary osteoclasts and human osteoblast-like MG63 cells were tested on strontium-substituted monetite and strontium-substituted brushite, as well as on monetite and brushite, as controls. In both structures, strontium substitution for calcium amounted to about 6 at% and provoked enlargement of the cell parameters and morphologic variations. Cumulative release in physiological solution increased linearly over time and was greater from brushite (up to about 160 and 560 mg/L at 14 days for Sr and Ca, respectively) than from monetite (up to about 90 and 250 mg/L at 14 days for Sr and Ca, respectively). The increasing viability of osteoblast-like cells over time, with the different expression level of some typical bone markers, indicates a more pronounced trigger toward osteoblast differentiation and osteoclast inhibition by brushite materials. In particular, the inhibition of cathepsin K and tartrate-resistant acid phosphatase at the gene and morphological levels suggests strontium-substituted brushite can be applied in diseases characterized by excessive bone resorption.

Permeability of P. gingivalis or its metabolic products through collagen and dPTFE membranes and their effects on the viability of osteoblast-like cells: an in vitro study.

Membrane exposure is a widely reported and relatively common complication in Guided Bone Regeneration (GBR) procedures. The introduction of micro-porous dPTFE barriers, which are impervious to bacterial cells, could reduce the technique sensitivity to membrane exposure, even if there are no studies investigating the potential passage of bacterial metabolites through the barrier. Aim of this study was the in vitro evaluation of the permeability of three different GBR membranes (dPTFE, native and cross-linked collagen membranes) to Porphyromonas gingivalis; in those cases, where bacterial penetration could not be observed, another purpose was the analysis of the viability and differentiation capability of an osteosarcoma (U2OS) cell line in presence of bacteria eluate obtained through membrane percolation. A system leading to the percolation of P. gingivalis broth culture through the experimental membranes was arranged to assess the permeability to bacteria after 24 and 72h of incubation. The obtained solution was then added to U2OS cell cultures which underwent, after 10days of incubation, MTT and red alizarin essays. The dPTFE membrane showed resistance to bacterial penetration, while both types of collagen membranes were crossed by P. gingivalis after 24h. The bacteria eluate filtered through dPTFE membrane didn't show any toxicity on U2OS cells. Results of this study demonstrate that dPTFE membranes can contrast the penetration of both P. gingivalis and its metabolites toxic for osteoblast-like cells. The toxicity analysis was not possible for the collagen membranes, since permeability to bacterial cells was observed within the first period of incubation.

Evaluation of the Effects of Mouthwash on the Morphology and Cell Viability of Osteoblast-Like Cells.

This study evaluated the effects of multiple mouthwashes on the cellular viability or the morphology of preosteoblasts. Mouse calvarial osteoblast-like cells were cultured and treated with mouthwashes of (1) benzydamine hydrochloride; (2) cetylpyridinium chloride and benzalkonium chloride; (3) methyl salicylate, menthol, eucalyptol, and thymol; and (4) sodium fluoride, xylitol, and chitosan. The treatment times were 30 seconds, 90 seconds, and 270 seconds. Cell morphology was evaluated with a microscope, and the viability of the treated cells was analyzed quantitatively using a commercially available kit. The untreated control group exhibited well-stretched fibroblast-like morphology. Treatment with mouthwash resulted in morphological changes in all groups. Treatment with sodium fluoride resulted in more noticeable changes. Treatment with mouthwash for 30 seconds produced a significant decrease in cell viability. An increase in time to 90 and 270 seconds did not produce additional noticeable changes. To conclude, commercially available mouthwashes created changes in cell morphology and decreased the cell viability of osteoblast-like cells irrespective of ingredients and treatment time.

Dose- and time-dependent effects of taxifolin on viability and mineralization markers of osteoblast-like cells

The current study evaluated the effects of taxifolin treatments on the viability of osteoblast-like cells, and on the expression of early mineralization markers, as part of the ongoing search for new endodontic materials able to induce periapical healing without causing cytotoxicity. Saos-2 osteoblast-like cells were exposed to different concentrations of taxifolin (5 and 10 µM), applied as pretreatments either for 24h and 72h, or continuously throughout the experimental protocol. Cell viability using the methylthiazole tetrazolium (MTT) assay, alkaline phosphatase activity using thymolphthalein monophosphate assays, deposition of mineralized nodules using alizarin red staining, and expression of ALP and COL-1 by qPCR were determined after 6 and 13 days of treatment. The data were analyzed statistically (p<0.05). Taxifolin was not cytotoxic in the concentrations tested. Pretreatments with taxifolin for 24h and 72h at 10 µM stimulated ALP activity, and increased mineralized nodule deposition by Saos-2 cells. Continuous treatment with taxifolin was not effective in stimulating ALP activity and mineralization. ALP and COL-1 gene expression increased with taxifolin pretreatments, since the highest mRNA levels were observed after 72h of pretreatment with taxifolin at 10 µM on day 13. In conclusion, taxifolin was cytocompatible, and induced mineralization markers when applied for short periods in osteoblast-like cell culture.

The effects of Fe3+ and Co2+ substitution in Ca10-x-yFexCoy(PO4)6(OH)2 hydroxyapatite nanoparticles: Magnetic, antibacterial, and improved drug release behavior

The mineral constituent of the bone contains non-stoichiometric hydroxyapatite with various substitutional ions. Iron (Fe) and cobalt (Co) are fundamental cofactors, which influence cell respiration and mitosis, respectively. In this study, undoped, Fe3+-, Co2+-, and dually-doped HA nanoparticles (NPs) were synthesized by the hydrothermal method. The Fe+CoCa+Fe+Co molar ratio was varied between 0.02 and 0.2. Samples were analyzed using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), vibrating sample magnetometry (VSM), Fourier-transformed infrared spectroscopy (FT-IR), inductively coupled plasma optical emission spectroscopy (ICP-OES), and biological assessment. XRD results confirmed the formation of the hexagonal HA crystal structure. The crystallite size was reduced from 34.6 nm to 4.4 nm. Also, the c-axis dimension and the degree of crystallinity were reduced in all the doped samples. The FESEM results showed a change of morphology from rod-like in the undoped nHA into a sphere-like morphology in the doped-samples. With the addition of ferromagnetic dopant, the magnetic behavior of samples altered from diamagnetic to paramagnetic-like and ferromagnetic behavior. Bioactivity assessment indicated the formation of the HA particle on the surface of all synthesized materials. The antibacterial test demonstrated antibacterial activity against gram-negative (−) E. coli. Moreover, the antibiotic-impregnated samples had a synergistic effect on both gram (−), E. coli, as well as gram (+), S. aureus, bacteria. The MTT evaluation revealed the enhanced cell viability of osteoblast-like cells in the dually-doped NPs. Based on this survey, we can strongly emphasize the potential for bone bioactivity and antibacterial feature of these newly developed samples.

The beneficial effect of cold atmospheric plasma on parameters of molecules and cell function involved in wound healing in human osteoblast-like cells in vitro

The aim of this study was to analyse the effect of cold atmospheric plasma (CAP) on human osteoblast-like cells in vitro. Additionally, underlying intracellular mechanisms were to be studied. Human osteoblast-like (MG63) cells were exposed to CAP for 60 s. The effects of CAP on key molecules essential for the wound healing response were studied using real-time PCR, ELISA and immunocytochemistry. For studying intracellular signalling pathways, MAP kinase MEK 1/2 was blocked. Cell viability was analysed by an XTT assay and with an EVE automated cell counter. Cell migration was examined by an in vitro wound healing assay.CAP exposition on osteoblast-like cells caused a significant upregulation of interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)α, cyclooxygenase (COX)2, collagen (COL) 1α, matrix metalloproteinase (MMP)1, Ki67, proliferating-cell-nuclear-antigen (PCNA) and chemokine ligand (CCL)2 mRNA expression at 1 day. Interestingly, after blocking of MAP kinase, CAP-induced upregulation of Ki67 was inhibited by 57%. Moreover, CAP treatment improved significantly osteoblast-like cell viability as compared to untreated cells at 1 day. Beneficial effect of CAP treatment was shown by an in vitro wound healing assay, displaying a significant faster wound closure. Our findings provide evidence that CAP exposure effects gene and protein regulation in human osteoblast-like cells. Furthermore, CAP treatment has a positive impact on wound closure in an in vitro setting and might improve existing concepts of hard tissue regeneration in the future.

A radiopaque calcium phosphate bone cement with long-lasting antibacterial effect: From paste to injectable formulation

The development of infections still represents a severe problem in orthopedic field. In this work, we developed an anti-microbial and radiopaque calcium phosphate bone cement with a long-lasting inhibitory activity thanks to the addition of gentamicin sulphate-loaded solid lipid microparticles obtained by spray congealing. Cements containing gentamicin both added into cement powder and loaded into microparticles were prepared and characterized and their properties were compared. The results of structural, morphological, mechanical and in vitro characterizations indicate that inclusion of gentamicin into microparticles is a good approach in order to obtain materials able to display a strong inhibition towards the growth of Gram-negative, as well as Gram-positive bacteria and to enhance the viability of osteoblast-like cells. All the compositions have an excellent activity also against clinical isolates, including multi drug resistant phenotypes. In particular, cements containing gentamicin-loaded microparticles display a strong and long-term inhibitory activity. Suitable modification of the liquid/powder ratio provided injectable formulation, whereas addition of BaSO4 produced radiopacity. All the formulations display good injectability and cohesion, and no evidence of demixing.

Lithium chloride improves bone filling around implants placed in estrogen-deficient rats

ObjectiveThis study evaluated the ability of lithium chloride (LiCl) to increase bone filling (BF) around threaded titanium implants inserted in estrogen-deficient rats and, thein-vitro effects of this drug on osteoblast-like cell viability, proliferation, mineralization and expression of bone-related markers. DesignIn vivo: Rats received sham surgery plus water (Estrogen-sufficient group), ovariectomy plus water (Estrogen-deficient group) or ovariectomy plus LiCl (150 mg/kg/every other day) (LiCl/estrogen-deficient group). On the 21st day after ovariectomy/sham surgeries, a threaded titanium implant was inserted in the rat tibia. BF and the number of TRAP + cells were assessed at 10, 20 and 30 days after implant placement. In vitro: Osteosarcoma SAOS-2 cells were exposed to 0, 0.01, 0.05, and 0.1 mM of LiCl; cell proliferation, viability, mineralization (alizarin red staining) and gene expressions of RUNX-2, OCN, OPN, BSP and ALP (Real Time PCR) were estimated in the cultures. ResultsIn vivo: The estrogen-sufficient and LiCl/estrogen-deficient groups demonstrated higher percentages of BF, within the limits of implant threads, than the estrogen-deficient group at 20 and 30 days (p < 0.05). The number of TRAP + cells was lower in LiCl/estrogen-deficient than in the estrogen-deficient group at all experimental times (p < 0.05). In vitro: Cell cultures exposed to LiCl (0.01 or 0.05 mM) exhibited larger areas of mineralized matrix than the non-exposed cultures (p < 0.05) and demonstrated the highest expressions of the genes investigated. ConclusionLiCl treatment improved BF around threaded titanium implants inserted in estrogen-deficient rats and stimulated matrix mineralization and overexpression of bone-formation markers in osteoblastic cells in culture.

Mechanical, corrosion, and biocompatibility properties of Mg-Zr-Sr-Sc alloys for biodegradable implant applications

Magnesium (Mg) and its alloys are considered promising biodegradable implant materials because of their strength and natural degradation in the human body. However, the high corrosion rate of pure Mg in the physiological environment leads to rapid degradation before adequate bone healing. This mismatch between bone healing and the degradation of Mg implants supports the development of new Mg alloys with the addition of other suitable alloying elements in order to achieve simultaneously high corrosion resistance and desirable mechanical properties. This study systematically investigates the microstructure, mechanical properties, corrosion behavior, and biocompatibility of Mg-based alloys with the addition of different concentrations of scandium (Sc), i.e., Mg-0.6Zr-0.5Sr-xSc (x = 0.5, 1, 2, 3 wt.%). Results indicated that high concentration of Sc in strontium (Sr)-containing Mg alloys can alter their microstructures by suppressing the intermetallic phases along the grain boundaries and improve the corrosion resistance by forming chemically stable Sc oxide layers on the surfaces of the Mg alloys. Cytotoxicity assessment revealed that the Sc containing Mg alloys did not significantly alter the viability of human osteoblast-like SaOS2 cells. This study highlights the advantages of using Sc as an alloying element to simultaneously tune Mg alloys with higher strength and slower degradation. Statement of significanceRare earth elements such as scandium (Sc) with both a high solid-solubility and strong affinity towards oxygen can improve the mechanical and corrosion properties of magnesium (Mg) alloys. However, the feasibility of Sc-containing Mg alloys as biodegradable implant materials is scarcely reported. This study investigates the effects of different Sc concentrations on the mechanical, corrosion, and biocompatibility properties of Mg-Zr-Sr-Sc alloys. Our findings indicated that the addition of Sc significantly improves the mechanical and corrosion properties of Mg-Zr-Sr alloys. Moreover, in vitro cytotoxicity assessment of the Mg-Zr-Sr-Sc alloys did not show any adverse effects on the viability of osteoblast-like cells.

Influence of Ag alloying on the antibacterial properties, bio-corrosion resistance and biocompatibility of α-Nb5Si3 nanocrystalline coating

To improve the corrosion resistance and impart the bioactivity and antibacterial functionalities to titanium alloys for biomedical applications, α-(Nb1-xAgx)5Si3 compounds, with three different Ag contents, were deposited on Ti–6Al–4V by double cathode glow discharge method. The new α-(Nb1-xAgx)5Si3 coatings, each about 16 μm in thickness, exhibited a compact uniform structure, composed of equiaxed nanocrystalline grains. Nanoindentation measurements revealed that Ag alloying reduced the hardness (H) and elastic modulus (E) values of the α-(Nb1-xAgx)5Si3 coatings. Compared to Ti–6Al–4V, the α-(Nb1-xAgx)5Si3 coatings exhibited improved corrosion resistance in Ringer’s physiological solution, as well as newly added in-vitro bioactivity and antibacterial ability against both E. coli and S. aureus. A MTT assay experiment shows that the two α-(Nb1-xAgx)5Si3(x = 0 and 0.05) coatings were as non-cytotoxic as bare Ti-6Al-4V. However, the MC3T3-E1 osteoblast-like cell viability for the α-(Nb0.9Ag0.1)5Si3 coating was slightly reduced, suggesting that the proliferation of MC3T3-E1 osteoblast-like cell was affected to some degree by excess Ag added to α-Nb5Si3. Overall, the α-(Nb0.95Ag0.05)5Si3 coating provides an attractive combination of good bioactivity, high corrosion resistance and new antibacterial function, and thus demonstrates great potential for applications in orthopedic devices.

Anti-inflammatory and antimicrobial activity of bioactive hydroxyapatite/silver nanocomposites

Biomaterials are often used in orthopedic surgery like cavity fillings. However, related complications often require long-term systemic antibiotics, device removal, and extended rehabilitation. Hydroxyapatite/silver (HA/Ag) composites have been proposed as implantation biomaterials owing to the osteogenic properties of hydroxyapatite and to the antimicrobial efficiency of silver. Nevertheless, higher silver concentrations induce cytotoxic effects. The aim of this study was to synthesize and characterize HA/Ag nanocomposites that will allow us to use lower concentrations of silver nanoparticles with better antimicrobial efficiency and anti-inflammatory properties. The characterization of HA/Ag was performed by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Fourier-transform infrared spectra, X-ray photoelectron spectroscopy, and laser diffraction. Bioactivity was evaluated under a simulated body fluid. The viability of osteoblast like-cells (MG-63) was determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) and the antimicrobial activity was evaluated by the standard McFarland method. The detection of nitric oxide was measured by a colorimetric assay and the inflammatory cytokines by flow cytometry. We obtained particulate composites of calcium phosphates identified as hydroxyapatite and silver nanoparticles. The bioactivity of the HA/Ag nanocomposites on SFB was confirmed by apatite formations. The viability of MG-63 cells was not affected. We also found antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans owing to the presence of silver nanoparticles at non-cytotoxic concentrations. HA/Ag reduced the release of nitric oxide and decreased the secretion of IL-1 and TNF-α in cells stimulated with Lipopolysaccharide (LPS). In conclusion, the inflammatory and antimicrobial capacity of the HA/Ag nanocomposites, as well as its bioactivity and low cytotoxicity make it a candidate as an implantation biomaterial for bone tissues engineering and clinical practices in orthopedic, oral and maxillofacial surgery.

Silver-loaded chitosan coating as an integrated approach to face titanium implant-associated infections: analytical characterization and biological activity.

The present work focuses on the idea to prevent and/or inhibit the colonization of implant surfaces by microbial pathogens responsible for post-operative infections, adjusting antimicrobial properties of the implant surface prior to its insertion. An antibacterial coating based on chitosan and silver was developed by electrodeposition techniques on poly(acrylic acid)-coated titanium substrates. When a silver salt was added during the chitosan deposition step, a stable and scalable silver incorporation was achieved. The physico-chemical composition of the coating was studied by X-ray photoelectron spectroscopy (XPS), while atomic force microscopy in intermittent contact mode (ICAFM) was used to explore the coating morphology. The amount of silver released from the coating up to 21days was evaluated by inductively coupled plasma mass spectrometry (ICP-MS). The capability of the proposed coating to interact in vitro with the biological environment in terms of compatibility and antibacterial properties was assessed using MG-63 osteoblast-like cell line and S. aureus and P. aeruginosa strains, respectively. These studies revealed that a coating showing a silver surface atomic percentage equal to 0.3% can be effectively used as antibacterial system, while providing good viability of osteoblast-like cells after 7days. The antibacterial effectiveness of the prepared coating is mainly driven by a contact killing mechanism, although the low concentration of silver released (below 0.1ppm up to 21days) is enough to inhibit bacterial growth, advantaging MG-63 cells in the race for the surface.

Spark anodization of titanium-zirconium alloy: surface characterization and bioactivity assessment.

Titanium (Ti) and its alloys have been popularly used as implant biomaterial for decades. Recently, titanium-zirconium (TiZr) alloy has been developed as an alternative implant material with improved strength in load bearing areas. Surface modification is one of the key factors to alter the surface properties to hasten osseointegration. Spark anodic oxidation (anodization) is one such method that is reported to enhance the bone formation around implants. This study aims to anodize TiZr and study its surface characteristics and cytocompatibility by cell culture experiments using osteoblast-like cells. Titanium (Ti) and TiZr discs were anodized in an electrolyte containing DL-α-glycerophosphate and calcium acetate (CA) at 300 V. The surface characteristics were analyzed by scanning electron microscopy, electron dispersive spectroscopy, X-ray diffraction (XRD), atomic force microscopy and goniometry. Using osteoblast-like cells viability, proliferation, differentiation and mineralization was assessed. The anodized surfaces demonstrated increased oxygen, entrapped calcium and phosphorous from the electrolyte used. XRD analysis confirmed the presence of anatase in the oxide layer. Average roughness increased and there was a significant decrease in contact angle (P < 0.01) following anodization. The anodized TiZr (aTiZr) surfaces were more nano-porous compared to anodized Ti (aTi). No significant difference was found in the viability of cells, but after 24 h the total number of cells was significantly higher (P < 0.01). Proliferation, alkaline phosphatase activity and calcium deposits were significantly higher on anodized surfaces compared to machined surfaces (P < 0.05, ANOVA). Anodization of TiZr resulted in a more nanoporous and hydrophilic surface than aTi, and osteoblast biocompatibility appeared comparable to aTi.

Osteoarticular cells tolerate short-term exposure to nitisinone-implications in alkaptonuria.

Alkaptonuria (AKU) is a rare genetic disease resulting in severe, rapidly progressing, early onset multi-joint osteoarthropathy. A potential therapy, nitisinone, is being trialled that reduces the causative agent; homogentisic acid (HGA) and in a murine model has shown to prevent ochronosis. Little is currently known about the effect nitisinone has on osteoarticular cells; these cells suffer most from the presence of HGA and its polymeric derivatives. This led us to investigate nitisinone's effect on chondrocytes and osteoblast-like cells in an in vitro model. Human C20/A4 immortalized chondrocytes, and osteosarcoma cells MG63 cultured in DMEM, as previously described. Confluent cells were then plated into 24-well plates at 4 × 10(4) cells per well in varying concentrations of nitisinone. Cells were cultured for 7 days with medium changes every third day. Trypan blue assay was used to determine viability and the effect of nitisinone concentration on cells. Statistical analysis was performed using analysis of variance, and differences between groups were determined by Newman-Keuls post-test. Analysis of C20/A4 chondrocyte and MG63 osteoblast-like cell viability when cultured in different concentrations of nitisinone demonstrates that there is no statistically significant difference in cell viability compared to control cultures. There is currently no literature surrounding the use of nitisinone in human in vitro models, or its effect on chondrocytes or osteoblast like cells. Our results show that nitisinone does not appear detrimental to cell viability of chondrocytes or osteoblast-like cells, which adds to the evidence that this therapy could be useful in treating AKU.

Evaluation of antibacterial activity and osteoblast-like cell viability of TiN, ZrN and (Ti1-xZrx)N coating on titanium

PURPOSEThe aim of this study was to evaluate antibacterial activity and osteoblast-like cell viability according to the ratio of titanium nitride and zirconium nitride coating on commercially pure titanium using an arc ion plating system.MATERIALS AND METHODSPolished titanium surfaces were used as controls. Surface topography was observed by scanning electron microscopy, and surface roughness was measured using a two-dimensional contact stylus profilometer. Antibacterial activity was evaluated against Streptococcus mutans and Porphyromonas gingivalis with the colony-forming unit assay. Cell compatibility, mRNA expression, and morphology related to human osteoblast-like cells (MG-63) on the coated specimens were determined by the XTT assay and reverse transcriptase-polymerase chain reaction.RESULTSThe number of S. mutans colonies on the TiN, ZrN and (Ti1-xZrx)N coated surface decreased significantly compared to those on the non-coated titanium surface (P<0.05).CONCLUSIONThe number of P. gingivalis colonies on all surfaces showed no significant differences. TiN, ZrN and (Ti1-xZrx)N coated titanium showed antibacterial activity against S. mutans related to initial biofilm formation but not P. gingivalis associated with advanced periimplantitis, and did not influence osteoblast-like cell viability.

Hyaluronic Acid as a Matrix for Increased Functionality of Biomedical Alloys

Despite extensive knowledge on the various methods for surface modification and interface formation, many questions still remain unresolved, especially regarding the relationships between composition of the bio-environment and biomechanical, structural and chemical properties of metal surface. In vitro corrosion studies were mostly carried out is simple solutions of inorganic salts, which can be regarded only as first tests of in vivo behavior of a metal, but not sufficient for deeper understanding of in vivo behavior (1-3). Some studies were performed in biologically more relevant media like MEM and serum; some investigated the effect of addition of protein or amino acids to solution of inorganic salts (2). Hyaluronic acid (HA) is a component of synovial joint fluid that regulates many important physiological and pathophysiological reactions. It is a glycosaminoglycan (GAG) or mucopolysaccharide, a long, unbranched polysaccharide composed of repeating units of disaccharide N-acetyl-D-glucosamine and D-glucuronic acid ‒ the only non-sulfated GAG and a high molecular mass polymer in excess of 106Da. It affects cell proliferation and migration and is responsible for the viscosity and resistance to compressive stress of synovial fluid. The behaviour of orthopaedic alloys in its presence is scarcely known and needs to be assessed.It was recently reported (4) that the addition of HA significantly affect the behavior of CoCrMo alloy, especially in simulated Hanks’ physiological solution containing inorganic salts. It results in the formation of a thick layer of calcium phosphate, which is approximately ten times thicker than that in the absence of hyaluronic acid. This layer is homogeneous at the nano-level. Due to its formation, the underlying layer of chromium oxide cannot be detected. The presence of Ca2+ and PO4 3 -ions is essential for the interaction between the chromium oxide surface and the hyaluronic chain. Under the experimental conditions used the addition of hyaluronic acid does not statistically significantly affect the viability of osteoblast-like cells but does increase the activity of alkaline phosphatase, indicating its beneficial effect on osteogenic activity.In addition to osseointegration ability, another important functional property of biomedical, especially orthopaedic alloy, is its ability to resist infection. The antimicrobial effect of silver salts has been well known; recently the use of silver nanoparticles as effective microbial growth inhibitor has been reported and recognized for possible applications for diverse medical devices (5). The combination of HA and silver nanoparticles will be presented as a way of increasing functional performance of orthopaedic alloy. Method of preparation includes green synthesis of silver nanoparticles where HA plays a role of reducing and stabilizing agent (6). Synthesized complex was characterized using several experimental methods (UV/Vis, FTIR, XPS, SEM, TEM). When deposited onto metal plates, its antimicrobial activity was assessed for resistance to attachment of common bacterial strains.

Characterization and cytocompatibility of an antibiotic/chitosan/cyclodextrins nanocoating on titanium implants

A novel ciprofloxacin loaded chitosan nanoparticle-based coating onto titanium substrates has been developed and characterized to obtain an orthopaedic implant surface able to in situ release the antibiotic for the prevention of post-operative infections. Ciprofloxacin loaded chitosan nanoparticles were obtained using the combination of sulfobutyl ether-beta-cyclodextrin and gamma-cyclodextrin. The resulting nanoparticulate system was characterized by TEM, HPLC and XPS. Particle size was in the range 426–552nm and zeta potential values were around +30mV. This antibacterial coating was able to in vitro inhibit two nosocomial Staphylococcus aureus strains growth, with a reduction of about 20 times compared to controls. No impairment in MG63 osteoblast-like cells viability, adhesion and gene expression were detected at 48h, 7 and 14 days of culture. Overall, the investigated coating represents a promising candidate for the development of a new antibiotic carrier for titanium implants.