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PubMed1999

Surface roughness modulates the response of MG63 osteoblast-like cells to 1,25-(OH)(2)D(3) through regulation of phospholipase A(2) activity and activation of protein kinase A.

Implant surface roughness influences osteoblast proliferation, differentiation, and local factor production. Moreover, the responsiveness of osteoblasts to systemic hormones such as 1, 25-(OH)(2)D(3) is altered by the effects of surface roughness; on the roughest Ti surfaces the effects of roughness and 1, 25-(OH)(2)D(3) are synergistic. Prostaglandin E(2) (PGE(2)) appears to be involved in mediating the effects of surface roughness on the cells, as well as in the response to 1,25-(OH)(2)D(3). However, it is not yet known through which signaling pathways surface roughness exerts its effects on the response of osteoblasts to 1, 25-(OH)(2)D(3). The present study examined the potential role of protein kinase A (PKA), phospholipase A(2)(PLA(2)), and protein kinase C (PKC) in this process. MG63 osteoblast-like human osteosarcoma cells were cultured on cpTi disks with R(a) values of 0. 54 microm (PT), 4.14 microm (SLA), or 4.92 microm (TPS). PKA was inhibited by adding H8 to the cultures; similarly, PLA(2) was inhibited with quinacrine or activated with melittin, and PKC was inhibited with chelerythrine. Inhibitors or activators were included in the culture media through the entire culture period or for the last 24 h of culture. In addition, cultures were treated for 24 h with inhibitors or activators in the presence of 1,25-(OH)(2)D(3). The effects on cell number and alkaline phosphatase specific activity were determined after 24 h; PKC activity was determined after 9 min and at 24 h. Cell number was reduced on rough surfaces, and alkaline phosphatase activity was increased. 1,25-(OH)(2)D(3) had a synergistic effect with surface roughness on alkaline phosphatase. However, neither surface roughness nor 1,25-(OH)(2)D(3) had an effect on PKC. H8 treatment for 24 h inhibited cell number and alkaline phosphatase on all surfaces; however, when it was present throughout the culture period, the PKA inhibitor had no effect on cell number, but decreased alkaline phosphatase-specific activity. H8 reduced the 1,25-(OH)(2)D(3)-mediated effect on cell number and alkaline phosphatase. Quinacrine inhibited cell proliferation and alkaline phosphatase on all surfaces and further reduced the 1,25-(OH)(2)D(3)-dependent decreases in both parameters. Melittin had no effect when applied for 24 h and did not modify the 1,25-(OH)(2)D(3) effect; however, when present throughout the culture period, it caused a decrease in proliferation and an increase in enzyme activity. Chelerythrine, the PKC inhibitor, only inhibited cell proliferation when it was present throughout the entire culture period. However, it decreased alkaline phosphatase in cultures treated for 24 h, but increased enzyme activity when it was present for the entire culture period. The results indicate that surface roughness and 1,25-(OH)(2)D(3) both mediate their effects through PLA(2) which catalyzes the rate-limiting step in PGE(2) production. Further downstream, PGE(2) activates PKA. Surface roughness-dependent effects are also mediated through PKC, but only after the cells have reached confluence and are undergoing phenotypic maturation. The effect of surface roughness on responsiveness to 1,25-(OH)(2)D(3) is mediated through PLA(2)/PKA and not through PKC.

Bioprosthesis↗

PubMed2005

Improvement of in vitro titanium bioactivity by three different surface treatments.

OBJECTIVE: Dental implants are usually made from commercially pure titanium or titanium alloys. The aim of this investigation was to determine the influence of surface treatments of commercially pure titanium samples on in vitro bioactivity. METHODS: Commercially pure (cp) titanium (Ti) sheets were submitted to three different surface treatments, including, for all samples, etching with an HCl/H(2)SO(4) solution. Part of each etched sample was further submitted either to anodic oxidation by using an H(3)PO(4) solution or to thermal oxidation. Treated and non-treated samples were analyzed by using scanning electron microscopy (SEM), profilometry and photoelectron X-ray spectroscopy (XPS). The in vitro assessment was carried out through the immersion of samples in simulated body fluid (SBF). In vitro testing was carried out by SEM and by the determination of calcium (Ca) content in solution by atomic absorption spectrometry (AAS). The non-treated titanium samples were used as the control group. RESULTS: This study has shown that, after up to 7-day exposure, a calcium phosphate layer precipitated only on samples submitted to at least one of the three treatments used. This result, based on SEM images, is in good agreement with Ca content and XPS analysis, in which remarkable effects of surface modifications on Ti samples are highlighted. SIGNIFICANCE: These results suggest that suitable surface treatments, such as employed here, may improve in vitro titanium bioactivity in a SBF solution at 37 degrees C. This behavior suggests a possibility of a further favorable in vivo response.

Acid Etching, Dental↗

PubMed1983

Stiffness and inelastic deformation in acrylictitanium composite implant materials under compression.

A variety of acrylic bone cement-metal composite materials were prepared and tested in simple compression at 37 degrees C in order to evaluate the mechanical behavior of these materials for possible use in bone replacement. The stiffness of the composite was of particular concern, and a simple rule of mixture was used to raise the modulus of acrylic bone cement. The reinforcement of the cement was accomplished by titanium and Ti-6Al-4V in different forms, e.g., wire, sheet, wire mesh, and powder. Test results demonstrated that the stiffness of the bone cement could indeed be increased by a desired amount to that of bone. A 16% volume fraction consisting of 25 0.10 cm diam Ti-6Al-4V wires increased the modulus of the bone cement by 380% to a value comparable to the modulus of cortical bone. Titanium sheet was nearly as effective as wires in increasing the modulus of bone cement, while titanium mesh was not a significantly effective reinforcing material. The amount of titanium powder added to the bone cement did not alter the compliance of the matrix material. In addition, as the flow strength increased, the strain to the point of load instability decreased. It was concluded that the extent of stiffening was governed by nonuniform deformation in the metal and the adjacent matrix which could be explained on the basis of geometrical considerations. Some of the limitations of the test results as well as methods of predicting the composite implant material behavior are also outlined.

Alloys↗

PubMed2005

Differential gene expression of collagen-binding small leucine-rich proteoglycans and lysyl hydroxylases, during mineralization by MC3T3-E1 cells cultured on titanium implant material.

Titanium implants create a unique ultrastructure (composed of a collagenous zone with relatively disorganized fibril morphology) at the bone-implant interface. The objective of this study was to investigate the temporal mRNA expression patterns, using real-time polymerase chain reaction, of type I collagen (COLI) and regulators for collagen fibrillogenesis, collagen-binding small leucine-rich proteoglycans (SLRPs) and lysyl hydroxylases (LHs), during mineralization, by MC3T3-E1 cells cultured on titanium (Ti). Lysates of the cultures on Ti and on plastic wells (Pl) for 10-50 d were used for the quantification of calcium and mRNA. Although the onset of calcium accumulation in the cultures on Ti (30-40 d) was slower than that of cultures on Pl (20-30 d), the gene expression patterns during mineralization were similar in cells cultured on either material. COLI and fibromodulin were up-regulated just before the onset of mineralization and then down-regulated. Lumican and LH1 were up-regulated just before the onset of mineralization and then returned to the baseline level. Decorin and LH2 were up-regulated at the late mineralization stage. Biglycan was down-regulated once at the early mineralization stage and then returned to the original level. LH3 was maintained at a steady level throughout. This study suggests actual but distinct roles of SLRPs and LHs in the formation of a unique ultrastructure at the bone-implant interface.

3T3 Cells↗

PubMed1995

Chemical modification of metallic implant surfaces with biofunctional proteins (Part 1). Molecular structure and biological activity of a modified NiTi alloy surface.

Human plasma fibronectin (pFN), an adhesive protein, was covalently immobilized onto an alkylaminosilane derivative of a NiTi substrate with glutaraldehyde through Schiff's base formation. The surface at different stages of the modification was characterized by X-ray photoelectron spectroscopy (XPS), and the amount of immobilized pFN was determined by a fluorometric method. The spreading behavior of human gingival fibroblasts was examined on the modified surface. The XPS spectra suggested that gamma-aminopropyltriethoxysilane (gamma-APS) was bonded to the surface through metallosiloxane bonds (Ti-O-Si) formed via a condensation reaction between the silanol end of gamma-APS and the surface hydroxyl group, with a highly cross-linked siloxane network formed after heat treatment of the silanized surface at 100 degrees C. The pFN was immobilized at the surface density of 1.1 micrograms.cm-2, and significantly promoted fibroblast spreading, suggesting that this chemical modification offers an effective means of controlling metal/cell interactions. These results may contribute to the development of bioactive metallic implants.

Biocompatible Materials↗

PubMed1994

A new technique for quantitation of metal particulates and metal reaction products in tissues near implants.

Tissue specimens retrieved from four regions adjacent to hip implants during revision surgery were subjected to a novel treatment to make possible the quantitative separation of residual metal particulates and metal reaction products (metal ions and metal-protein complexes). The tissues were exposed to sodium hypochlorite solution that degraded and solubilized them, liberating metal reaction product and leaving behind metal wear particles, which were separated by centrifugation. Atomic absorption spectrophotometry was used to analyze the concentrations of the separated metal ions and wear particles. Co ion concentrations were 0.05 to 0.9 mM, Cr ion concentrations were 0.04 to 2.1 mM, and of Ti ion concentrations were 0.30 to 0.60 mM. The weight of Co metal particles was 0.1 to 4.9 mg/100 mg tissue, of Cr metal particles 0.07 to 2.2 mg/100 mg of tissue, and Ti particles 0.09 to 5.2 mg/100 mg tissue; one black tissue sample contained 3333 mg Ti/100 mg tissue. No correlation was found between the concentrations of these two entities in the samples examined, probably due to the complex and varied processes creating them. The procedures discussed here will result in data that can help elucidate the separate contributions of metal reaction products and metal particulates to implant loosening.

Aged↗

PubMed1999

Histiocyte reaction in rabbit femurs to UHMWPE, metal, and ceramic particles in different sizes.

To assess the histologic reaction caused by biomaterial particles in different sizes around the bone-implant interface, we examined ultra-high molecular weight polyethylene (UHMWPE, average diameter of 11 microm), UHMWPE (99 microm), cobalt-chromium alloy (Co-Cr, 3.9 microm), stainless steel (SUS316L, 3.9 microm), alumina ceramics (3.9 microm), titanium alloy (Ti, 3.5 microm), Co-Cr (0.03 microm), and Ti (0.03 microm). After the longitudinal groove on a polymethylmethacrylate plug was filled with one type of the particles, the plug was inserted into the medullar canal of the distal end of rabbit femurs, and tissue block was resected 4 and 12 weeks after the insertion. Histiocytes were markedly accumulated around the particles of UHMWPE (11 microm), Co-Cr (3.9 microm), SUS316L (3.9 microm), Co-Cr (0.03 microm), and titanium alloy (0.03 microm). Around the UHMWPE particles (99 microm), a slight histiocytic reaction and bone formation were observed. Particles of alumina ceramics (3.9 microm) and titanium alloy (3.5 microm) which were in phagocytosable sizes also had few histiocytic reactions. Statistically, the material difference was more strongly related to the histiocyte reaction than to the particle size and calculated total surface area of particles. Our findings demonstrate that particles of different biomaterials and in different sizes induce different foreign-body histological reactions.

Aluminum Oxide↗

PubMed2005

The effect of surface chemistry modification of titanium alloy on signalling pathways in human osteoblasts.

Establishing and maintaining mature bone at the bone-device interface is critical to the long-term success of prosthesis. Poor cell adhesion to orthopaedic and dental implants results in implant failure. Considerable effort has been devoted to alter the surface characteristics of these biomaterials in order to improve the initial interlocking of the device and skeleton. We investigated the effect of surface chemistry modification of titanium alloy (Ti-6Al-4V) with zinc, magnesium or alkoxide-derived hydroxy carbonate apatite (CHAP) on the regulation of key intracellular signalling proteins in human bone-derived cells (HBDC) cultured on these modified Ti-6Al-4V surfaces. Western blotting demonstrated that modifying Ti-6Al-4V with CHAP or Mg results in modulation of key intracellular signalling proteins. We showed an enhanced activation of Shc, a common point of integration between integrins and the Ras/Mapkinase pathway. Mapkinase pathway was also upregulated, suggesting its role in mediating osteoblastic cell interactions with biomaterials. The signalling pathway involving c-fos (member of the activated protein-1) was also shown to be upregulated in osteoblasts cultured on the Mg and CHAP modified Ti-6Al-4V. Thus surface modification with CHAP or Mg may contribute to successful osteoblast function and differentiation at the skeletal tissue-device interface.

Alloys↗

PubMed2000

Effect of mechanical surface pretreatment on metal ion release.

The degree of metal ion dissolution from Ti-6Al-4V alloy hip replacement stems subjected to various mechanical and chemical surface pretreatments was analysed in vitro. High-dissolution rates were observed for nitric acid passivated samples that had been mechanically surface treated to increase the implant surface area. Significantly lower ion release levels were observed for mechanically treated samples which had been aged in de-ionised water. The application of an hydroxyapatite coating decreased the metal ion release from the nitric acid passivated samples (compared to the uncoated sample) and increased the metal ion dissolution from the aged samples. The dissolution behaviour of the samples is explained in terms of the diffusion processes occurring at the stem/solution interface and the morphological and chemical characteristics of the surface treated stems.

Alloys↗

PubMed2005

Effects of different titanium alloys and nanosize surface patterning on adhesion, differentiation, and orientation of osteoblast-like cells.

To test nanosize surface patterning for application as implant material, a suitable titanium composition has to be found first. Therefore we investigated the effect of surface chemistry on attachment and differentiation of osteoblast-like cells on pure titanium prepared by pulsed laser deposition (TiPLD) and different Ti alloys (Ti6Al4V, TiNb30 and TiNb13Zr13). Early attachment (30 min) and alkaline phosphatase (ALP) activity (day 5) was found to be fastest and highest, respectively, in cells grown on TiPLD and Ti6Al4V. Osteoblasts seeded on TiPLD produced most osteopontin (day 10), whereas expression of this extracellular matrix protein was an order of magnitude lower on the TiNb30 surface. In contrast, expression of the corresponding receptor, CD44, was not influenced by surface chemistry. Thus, TiPLD was used for further experiments to explore the influence of surface nanostructures on osteoblast adhesion, differentiation and orientation. By laser-induced oxidation, we produced patterns of parallel Ti oxide lines with different widths (0.2-10 microm) and distances (2-20 and 1,000 microm), but a common height of only 12 nm. These structures did not influence ALP activity (days 5-9), but had a positive effect on cell alignment. Two days after plating, the majority of the focal contacts were placed on the oxide lines. The portion of larger focal adhesions bridging two lines was inversely related to the line distance (2-20 microm). In contrast, the portion of aligned cells did not depend on the line distance. On average, 43% of the cells orientated parallel towards the lines, whereas 34% orientated vertically. In the control pattern (1,000 microm line distance), cell distribution was completely at random. Because a significant surplus of the cells preferred a parallel alignment, the nanosize difference in height between Ti surface and oxide lines may be sufficient to orientate the cells by contact guiding. However, gradients in electrostatic potential and surface charge density at the Ti/Ti oxide interface may additionally influence focal contact formation and cell guidance.

Alkaline Phosphatase↗

PubMed2006

Chronic peritoneal dialysis in children: catheter related complications. A single centre experience.

Despite advancements in catheter design and dialysis technique, catheter related complications still remain a common clinical problem in paediatric patients on chronic peritoneal dialysis (PD); in particular, infections are a common cause of patient's morbidity and technique failure. In the present paper, data on 89 catheters implanted between January 1986 and December 2002 are reviewed to analyse the major causes of complications and/or PD failure and to ascertain their optimal management. A total of 89 catheters were implanted in 78 patients at the start of chronic PD: 26 in children under 2 years of age, 14 in children aged 2-5 years and 49 in patients over 5 years. Mean age of patients was 76.1 +/- 73.0 months and median treatment time 14.5 +/- 13.1 months. All catheters were surgically implanted and partial omentectomy was performed in 70% of cases. Straight Tenckhoff catheters were used in 70 cases (78%), curled ones in 19 (22%). Sixty-three catheters (71%) had two cuffs, 26 (29%) a single cuff. The entry-site was the midline in 34 patients (38%) and the paramedian line in 55 patients (62%). Catheter survival rate was 80% at 12 months, 62% at 24 months and 58% at 36 and 48 months, respectively. The incidence of catheter-related complications was one episode every 6.4 PD-months, and they were mainly represented by peritonitis (61%), exit-site infections and tunnel infection (ESI + TI: 23%), catheter obstruction (5%), dislocation (3.5%), leakage (2.5%). After the introduction of curled single-cuff catheters, a considerable reduction in the peritonitis incidence was observed during the last 7 years. A more prolonged catheter survival was observed in older children (>5 vs. <2 years: P < 0.05). Leakage was less common in catheters with paramedian entry-site compared with catheters implanted on the midline. In 7 out of 11 (64%) patients with catheter obstruction, omentectomy had not been performed. Single-cuff catheters had a lower infection-rate than double-cuff catheter (P < 0.01). Single cuff-curled Tenckhoff catheter can be considered the first choice catheter. Single cuff-catheters are not associated with an increase of infections. The surgical technique requires a strict adherence to a standardized procedure and a dedicated team, in order to obtain a reduction of the complications, a prolonged catheter duration and a better quality of life.

Analysis of Variance↗

PubMed1997

Effect of electrochemically deposited apatite coating on bonding of bone to the HA-G-Ti composite and titanium.

The surfaces of hydroxyapatite-glass-titanium (HA-G-Ti) functionally gradient composite and titanium bars were treated with electrochemical apatite deposition, and a cathodic current was applied at 62 degrees C in a solution containing calcium and phosphate ions. Specimens with and without the electrochemical surface treatment were implanted in the femurs of Japanese white rabbits. The rabbits were sacrificed at 3, 6, and 9 weeks after implantation, and the bonding strengths of bone to these specimens were determined by a pull-out method. At 3 and 6 weeks after implantation the specimens with the electrochemical surface treatment showed larger values for the Weibull modulus and characteristic strengths than those of untreated specimens, whereas there was no remarkable difference in the results at 9 weeks. Especially the pull-out strengths of surface-treated specimens were significantly larger than the untreated ones at 3 weeks after implantation. Scanning electron microscopy and Fourier transform infrared absorption spectroscopy of the specimen surface after implantation demonstrated that formation of new bone was enhanced by the electrochemical surface treatment. It can be concluded that the electrochemical surface treatment undoubtedly contributes to the early stage fixation between bone and implant.

Animals↗

PubMed2006

[Examination of granuloma of revised cemented or cementless total hip arthroplasties using inductively coupled plasma atomic emission spectrometry (ICP-OES)].

INTRODUCTION: Aseptic loosening is the most common problem in total hip arthroplasty (THA). One main aspect is inflammatory reaction against wear particles of the prosthesis materials. Analysing failure mechanisms in THA analysis of the particles and their element distribution of revised granulomatous tissue is essential to improve materials used in THA. MATERIALS AND METHODS: 23 granulomas of revised THA due to aseptic loosening, 13 of which with metal on metal bearing (M/M), were analysed using inductively coupled plasma atomic emission spectrometry (ICP-OES). RESULTS: Elements Cr, Mn, Ni, Al, Cu, Zn, Cd, Ti, V, Zr, Nb and Fe could be detected. The maximum value of Cr was 23.88 ppb (parts per billion), Al 191.02 ppb, Ni 64.95 ppb and Zr 9.96 ppb. The highest value of Al could be found in cementless implants. The maximum value of the elements Cr and Ni could be detected in M/M. In cemented implants the highest value of Zr was found. DISCUSSION: The origin of Zr was the used bone cement in cemented THA. The elements Cr and Ni were significantly higher in M/M bearings. The highest value of Al was detected in granulomas of revised corund rough blasted cementless implants. The histopathologic findings of the revised M/M bearings have been published recently. Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-OES) could not show any differences of the alloying constituents in cases with or without allergic reactions. ICP-OES analysis seems to be not useful examination of histologic sections using SEM with cryotransfer unit.

Arthroplasty, Replacement, Hip↗

PubMed2004

Fluor-hydroxyapatite sol-gel coating on titanium substrate for hard tissue implants.

Hydroxyapatite (HA) and fluor-hydroxyapatite (FHA) films were deposited on a titanium substrate using a sol-gel technique. Different concentrations of F- were incorporated into the apatite structure during the sol preparation. Typical apatite structures were obtained for all coatings after dipping and subsequent heat treatment at 500 degrees C. The films obtained were uniform and dense, with a thickness of approximately 5 microm. The dissolution rate of the coating layer decreased with increasing F- incorporation within the apatite structure, which demonstrates the possibility of tailoring the solubility by a functional gradient coating of HA and FHA. The cell proliferation rate on the coating layer decreased slightly with increasing F- incorporation. The alkaline phosphatase (ALP) activity of the cells on all the HA and FHA coated samples showed much higher expression levels compared to pure Ti. This confirmed the improved activity of cell functions on the substrates with the sol-gel coating treatment.

Adsorption↗

PubMed2002

Ti4+ to Ti3+ conversion of TiO2 uppermost layer by low-temperature vacuum annealing: interest for titanium biomedical applications.

Because of the Ti(3+) defects responsibility for dissociative adsorption of water onto TiO(2) surfaces and due to the hydroxyls influence on the biological behavior of titanium, controlling the Ti(3+) surface defects density by means of low-temperature vacuum annealing is proposed to improve the bone/implant interactions. Experiments have been carried out on Ti-6Al-4V alloys exhibiting a porous surface generated primarily by chemical treatment. XPS investigations have shown that low-temperature vacuum annealing can create a controlled number of Ti(3+) defects (up to 21% Ti(3+)/Ti(4+) at 573 K). High Ti(3+) defect concentration is linked to surface porosity. Such surfaces, exhibiting high hydrophilicity and microporosity, would confer to titanium biomaterials a great ability to interact with surrounding proteins and cells and hence would favor the bone anchorage of as-treated implants.

Journal Article↗

PubMed2002

Diffusion studies in non-oxide ceramics: analytical aspects of the use of ion implanted stable tracers and SIMS.

The physical and chemical properties of complex non-oxide ceramic materials require advanced methods of diffusivity determination. In this study, we present a method based on the high-dose ion implantation of stable tracers in combination with secondary ion mass spectroscopy for depth profiling. The analytical basics, advantages and problems of the method are discussed for two examples of complex materials, the Si-B-C-N precursor ceramics and the Ti-based transition metal diborides. We demonstrate that is possible to measure the temperature dependence of diffusivities, especially for ceramic systems with low diffusivities, for systems that contain elements for which no suitable radioactive tracers exist for extended measurements.

Ceramics↗

PubMed1999

Structure and properties of cast binary Ti-Mo alloys.

Structure and properties of a series of binary Ti-Mo alloys with molybdenum contents ranging from 6 to 20 wt% have been investigated. Experimental results indicated that crystal structure and morphology of the cast alloys were sensitive to their molybdenum contents. The hexagonal alpha' phase c.p. Ti exhibited a feather-like morphology. When Mo content was 6 wt%, a fine, acicular martensitic structure of orthorhombic alpha" phase was observed. When Mo content was 7.5 wt%, the entire alloy was dominated by the martensitic alpha" structure. When Mo content was increased to 10 wt% or higher, the retained beta phase became the only dominant phase. Among all Ti-Mo alloys, the alpha" phase Ti-7.5Mo alloy had the lowest hardness. The bending strength of Ti-7.5Mo was similar to that of Ti-15Mo and Ti-13Nb-13Zr, and higher than c.p. Ti by nearly 60%. The bending modulus of the alpha"-dominated Ti-7.5Mo alloy was lower than that of Ti-15Mo by 22%, of Ti-6A1-4V by 47%, of Ti-13Nb-13Zr by 17%, and of c.p. Ti by 40%.

Alloys↗

PubMed2000

Phagocytosis of wear debris by osteoblasts affects differentiation and local factor production in a manner dependent on particle composition.

Wear debris is considered to be one of the main factors responsible for aseptic loosening of orthopaedic endoprostheses. Whereas the response of cells in the monocytic lineage to foreign materials has been extensively studied, little is known about cells at the bone formation site. In the present study, we examined the hypothesis that the response of osteoblasts to wear debris depends on the chemical composition of the particles. We produced particles from commercially pure titanium (cpTi), Ti-6Al-4V (Ti-A), and cobalt-chrome (CoCr) and obtained ultrahigh molecular weight polyethylene (UHMWPE; GUR 4150) particles from a commercial source. The equivalent circle diameters of the particles were comparable: 1.0 +/- 0.96 microm for UHMWPE; 0.84 +/- 0.12 microm for cpTi; 1.35 +/- 0.09 microm for Ti-A, and 1.21 +/- 0.16 microm for CoCr. Confluent primary human osteoblasts and MG63 osteoblast-like cells were incubated in the presence of particles for 24 h. Harvested cultures were examined by transmission electron microscopy to determine if the cells had phagocytosed the particles. Particles were found intracellularly, primarily in the cytosol, in both the primary osteoblasts and MG63 cells. The chemical composition of the particles inside the cells was confirmed by energy-dispersive X-ray analysis. Morphologically, both cell types had extensive ruffled cell membranes, less-developed endoplasmic reticulum, swollen mitochondria, and vacuolic inclusions compared with untreated cells. CpTi, Ti-A, and CoCr particles were also added to cultures of MG63 cells to assess their effect on proliferation (cell number) and differentiation (alkaline phosphatase activity), and PGE2 production. All three types of particles had effects on the cells. The effect on cell number was dependent on the chemical composition of the particles; Ti-A and CoCr caused a dose-dependent increase, while cpTi particles had a biphasic effect with a maximal increase in cell number observed at the 1:10 dilution. Alkaline phosphatase specific activity was also affected and cpTi was more inhibitory than Ti-A or CoCr. PGE2 production was increased by all particles, but the magnitude of the effect was particle-dependent: CoCr > cpTi > Ti-A. This study demonstrates clearly that human osteoblast-like cells and MG63 cells can phagocytose small UHMWPE, CoCr, Ti-A, and cpTi particles. Phagocytosis of the particles is correlated with changes in morphology, and analysis of MG63 response shows that cell proliferation, differentiation, and prostanoid production are affected. This may have negative effects on bone formation adjacent to an orthopaedic implant and may initiate or contribute to the cellular events that cause aseptic loosening by inhibiting bone formation. The effects on alkaline phosphatase and PGE2 release are dependent on the chemical composition of the particles, suggesting that both the type and concentration of wear debris at an implant site may be important in determining clinical outcome.

Aged↗