Proliferation Of Human Osteoblasts Research Articles

Importance of melastatin-like transient receptor potential 7 and magnesium in the stimulation of osteoblast proliferation and migration by platelet-derived growth factor

Bone is a dynamic tissue that is continuously being remodeled throughout life. Specialized cells called osteoclasts transiently break down old bone (resorption process) at multiple sites as other cells known as osteoblasts are replacing it with new tissue (bone formation). Usually, both resorption and formation processes are in balance and thereby maintain skeletal strength and integrity. This equilibrium is assured by the coordination of proliferation, migration, differentiation, and secretory functions of the osteoblasts, which are essential for adequate formation and resorption processes. Disturbances of this equilibrium may lead to decreased bone mass (osteoporosis), increased bone fragility, and susceptibility to fractures. Epidemiological studies have linked insufficient dietary magnesium (Mg(2+)) intake in humans with low bone mass and osteoporosis. Here, we investigated the roles of Mg(2+) and melastatin-like transient receptor potential 7 (TRPM7), known as Mg(2+) channels, in human osteoblast cell proliferation and migration induced by platelet-derived growth factor (PDGF), which has been involved in the bone remodeling process. PDGF promoted an influx of Mg(2+), enhanced cell migration, and stimulated the gene expression of TRPM7 channels in human osteoblast MG-63 cells. The stimulation of osteoblast proliferation and migration by PDGF was significantly reduced under culture conditions of low extracellular Mg(2+) concentrations. Silencing TRPM7 expression in osteoblasts by specific small interfering RNA prevented the induction by PDGF of Mg(2+) influx, proliferation, and migration. Our results indicate that extracellular Mg(2+) and TRPM7 are important for PDGF-induced proliferation and migration of human osteoblasts. Thus Mg(2+) deficiency, a common condition among the general population, may be associated with altered osteoblast functions leading to inadequate bone formation and the development of osteoporosis.

Connective tissue growth factor is a downstream mediator for preptin-induced proliferation and differentiation in human osteoblasts

Preptin, a newly isolated 34-amino-acid peptide hormone that is cosecreted with insulin and amylin from pancreatic beta-cells, has emerged as a regulatory element in bone metabolism, but its mechanism remains unclear. We assessed the effects of preptin on proliferation and differentiation of human osteoblasts and investigated the mechanism involved. Our results demonstrated that preptin promoted human osteoblasts proliferation and alkaline phosphatase activity. Suppression of connective tissue growth factor (CTGF), which was upregulated by preptin in a dose- and time-dependent manner, with small interfering RNA (siRNA) abolished the preptin-induced human osteoblasts proliferation and differentiation. Preptin induced activation of ERK mitogen-activated protein kinase (MAPK), but not p38 or JNK in human osteoblasts. Furthermore, pretreatment of human osteoblasts with the ERK inhibitor PD98059 abolished the preptin-induced CTGF secretion and blocked the promoting effect of preptin on osteoblasts proliferation and differentiation. These data demonstrated that preptin is involved in bone anabolism mediated by ERK/CTGF in human osteoblasts and may contribute to the preservation of bone mass observed in hyperinsulinemic states, such as obesity.

Functional α1‐ and β2‐adrenergic receptors in human osteoblasts

Central (hypothalamic) control of bone mass is proposed to be mediated through beta2-adrenergic receptors (beta2-ARs). While investigations in mouse bone cells suggest that epinephrine enhances both RANKL and OPG mRNA via both beta-ARs and alpha-ARs, whether alpha-ARs are expressed in human bone cells is controversial. The current study investigated the expression of alpha1-AR and beta2-AR mRNA and protein and the functional role of adrenergic stimulation in human osteoblasts (HOBs). Expression of alpha1B- and beta2-ARs was examined by RT-PCR, immunofluorescence microscopy and Western blot (for alpha1B-ARs). Proliferation in HOBs was assessed by (3)H-thymidine incorporation and expression of RANKL and OPG was determined by quantitative RT-PCR. RNA message for alpha1B- and beta2-ARs was expressed in HOBs and MG63 human osteosarcoma cells. alpha1B- and beta2-AR immunofluorescent localization in HOBs was shown for the first time by deconvolution microscopy. alpha1B-AR protein was identified in HOBs by Western blot. Both alpha1-agonists and propranolol (beta-blocker) increased HOB replication but fenoterol, a beta2-agonist, inhibited it. Fenoterol nearly doubled RANKL mRNA and this was inhibited by propranolol. The alpha1-agonist cirazoline increased OPG mRNA and this increase was abolished by siRNA knockdown of alpha1B-ARs in HOBs. These data indicate that both alpha1-ARs and beta2-ARs are present and functional in HOBs. In addition to beta2-ARs, alpha1-ARs in human bone cells may play a role in modulation of bone turnover by the sympathetic nervous system.

Anti-inflammatory drugs suppress proliferation and induce apoptosis through altering expressions of cell cycle regulators and pro-apoptotic factors in cultured human osteoblasts

It has been reported that anti-inflammatory drugs (AIDs) inhibited bone repair in animal studies, and suppressed proliferation and induced cell death in rat osteoblast cultures. In this study, we further investigated the molecular mechanisms of AID effects on proliferation and cell death in human osteoblasts (hOBs). We examined the effects of dexamethasone (10 −7 and 10 −6 M), non-selective non-steroidal anti-inflammatory drugs (NSAIDs): indomethacin, ketorolac, piroxicam and diclofenac (10 −5 and 10 −4 M), and COX-2 inhibitor: celecoxib (10 −6 and 10 −5 M) on proliferation, cytotoxicity, cell death, and mRNA and protein levels of cell cycle and apoptosis-related regulators in hOBs. All the tested AIDs significantly inhibited proliferation and arrested cell cycle at G0/G1 phase in hOBs. Celecoxib and dexamethasone, but not non-selective NSAIDs, were found to have cytotoxic effects on hOB, and further demonstrated to induce apoptosis and necrosis (at higher concentration) in hOBs. We further found that indomethacin, celecoxib and dexamethasone increased the mRNA and protein expressions of p27 kip1 and decreased those of cyclin D2 and p-cdk2 in hOBs. Bak expression was increased by celecoxib and dexamethasone, while Bcl-XL level was declined only by dexamethasone. Furthermore, the replenishment of PGE1, PGE2 or PGF2α did not reverse the effects of AIDs on proliferation and expressions of p27 kip1 and cyclin D2 in hOBs. We conclude that the changes in expressions of regulators of cell cycle (p27 kip1 and cyclin D2) and/or apoptosis (Bak and Bcl-XL) by AIDs may contribute to AIDs caused proliferation suppression and apoptosis in hOBs. This effect might not relate to the blockage of prostaglandin synthesis by AIDs.

Extracorporeal Shock Wave-Mediated Changes in Proliferation, Differentiation, and Gene Expression of Human Osteoblasts

The goal of this study was to determine whether cell proliferation, differentiation, and gene expression of primary human osteoblasts (hOB) are influenced by shock wave application (SWA). Osteoblast cultures were isolated from cancellous bone fragments and treated with 500 impulses of energy flux densities of 0.06 mJ/mm, 0.18 mJ/mm, 0.36 mJ/mm, and 0.50 mJ/mm. Twenty-four hours and 96 hours after SWA cell proliferation, alkaline phosphatase activity, and mineralization were analyzed. The global gene expression profiling was determined 96 hours after SWA employing Affymetrix HG-U133A microarrays. After 24 hours, hOB showed a dose-dependent increase in cell proliferation from 68.7% (at 0.06 mJ/mm, p = 0.002) up to 81.6% (at 0.5 mJ/mm, p = 0.001), which also persisted after 96 hours. Numbers of alkaline phosphatase-positive hOB increased after SWA treatment with peak levels of response between 0.18 mJ/mm and 0.5 mJ/mm after 24 hours. Mineralization was significantly higher in all groups compared with controls. Microarray analyses revealed SWA-induced differential expression of 94 genes involved in physiologic processes, cell homeostasis, and bone formation. Most intriguing was the up-regulation of multiple genes involved in skeletal development and osteoblast differentiation (e.g., PTHrP, prostaglandin E2-receptor EP3, BMP-2 inducible kinase, chordin, cartilage oligomeric matrix protein, matrillin). We showed that shock waves have direct dose-dependent stimulatory effects on proliferation and differentiation of osteoblasts from normal human cancellous bone. We demonstrated that several genes critical for osteoblast differentiation and function are regulated after SWA. Overall, data presented herein will aid further understanding of the osteogenic effect of shock waves and, in addition, will enhance current knowledge of the SWA-mediated gene expression.

The effects of silicate ions on human osteoblast adhesion, proliferation, and differentiation

Silicon has been shown to have important effects on skeletal development and repair, and soluble silicate ions have been found to stimulate the expression of type-I collagen in osteoblast-like cell cultures. Furthermore, silicon has been incorporated into the hydroxyapatite lattice and enhanced metabolic activity of human osteosarcoma cells was observed when cells were cultured on this material. In vivo assessments have demonstrated enhanced bioactivity of silicon-substituted hydroxyapatite (Si-HA) over pure HA. However, detailed mechanisms for the stimulative effects of Si-HA have not been described. In this study, we found that silicon substitution into hydroxyapatite affects the adhesion of human osteoblast-like cells (HOBs) in culture, with 0.8 wt % silicon substitution being optimal. In addition, metabolic activity and proliferation of HOBs were increased by supplementation of the growth medium with 30 microM silicon. It was determined that this response may depend on the proportion of cells at different stages of differentiation within the cultures.

Human osteoblasts adhesion and proliferation on magnesium-substituted tricalcium phosphate dense tablets

Tricalcium phosphate (TCP) is recognized as a promising bone replacement material due to its high bioactivity and resorbable properties. To mimic biological apatites, incorporation of magnesium (Mg) in TCP was proposed. Mg-substituted TCP (beta-TCMP) and beta-TCP dense tablets were obtained by pressing and sintering at 1,000 degrees C Mg-substituted calcium deficient apatite (Mg-CDA) and commercial TCP, respectively. The materials were characterized using X-ray diffraction, infrared spectroscopy and electron microscopy. Human osteoblast cells (SaOs2) were seeded onto the sintered tablets for 4 h, 24 h and 7 days. Results showed that Mg-CDA was completely transformed into beta-TCMP. Moreover, beta-TCMP stimulated adhesion and proliferation of human osteoblast cells. Consequently, the magnesium incorporation on calcium deficient apatites followed by sintering at 1,000 degrees C seems to be a useful path to obtain biocompatible and non cytotoxic dense tablets with TCP structure with potential application on bone engineering.

Biocompatibility and In Situ Growth of TiO2 Nanotubes on Ti Using Different Electrolyte Chemistry

Titania nanotube array was grown via anodization using different electrolyte chemistry to understand the influence of solution chemistry and pH on nanotube growth kinetics. One of the electrolytes was selected to evaluate the transformation in the surface morphology as a function of anodization time from 5 to 120 min. Contact angles were measured and surface energies were calculated on selected compositions for various duration of anodization time. It was noticed that contact angle decreased and surface energy increased with the onset of nanotube formation. Human osteoblast cell attachment and proliferation were studied using an osteo precursor cell line. Nanotube surface showed enhanced cell spreading, high cell proliferation, and abundant amount of extracellular matrix formation.

Proliferation and Differentiation of Human Osteoblasts within 3D printed Poly-Lactic-co-Glycolic Acid Scaffolds

Bone repair and regeneration can be enhanced through implantation of biocompatible and biodegradable scaffolds, which serve primarily as osteoconductive moieties. In this study, the mechanical properties and microenviroment of 3D printed poly-lactic-co-glycolic acid (PLGA) scaffolds are examined. Additionally, the proliferation and differentiation of human fetal osteoblasts are evaluated after 3 weeks of in vitro culture on the scaffolds. The results showed that the PLGA scaffolds examined had mechanical properties similar to that of trabecular bone, but was still much weaker compared to cortical bone. In addition to general porosity, the PLGA scaffolds also had micropores within macropore walls. Cultured human osteoblasts could proliferate upon seeding on the PLGA scaffolds. Alkaline phosphatase activity and osteonectin expression of the osteoblasts cultured on the PLGA scaffolds remained stable over three weeks, whilst expression of collagen type I and osteopontin decreased. The alkaline phosphatase activity of osteoblasts cultured on PLGA scaffolds is comparable with that from two commercially-available scaffolds - OPLA and collagen scaffolds (Becton-Dickinson (BD) Inc., Franklin Lakes, NJ, USA). Hence, the results suggested that the PLGA scaffolds examined are conducive for promoting osteogenesis.

Combining Electrospun Scaffolds with Electrosprayed Hydrogels Leads to Three-Dimensional Cellularization of Hybrid Constructs

A common problem in the design of tissue engineered scaffolds using electrospun scaffolds is the poor cellular infiltration into the structure. To tackle this issue, three approaches to scaffold design using electrospinning were investigated: selective leaching of a water-soluble fiber phase (poly ethylene oxide (PEO) or gelatin), the use of micron-sized fibers as the scaffold, and a combination of micron-sized fibers with codeposition of a hyaluronic acid-derivative hydrogel, Heprasil. These designs were achieved by modifying a conventional electrospinning system with two charged capillaries and a rotating mandrel collector. Three types of scaffolds were fabricated: medical grade poly(epsilon-caprolactone)/collagen (mPCL/Col) cospun with PEO or gelatin, mPCL/Col meshes with micron-sized fibers, and mPCL/Col microfibers cosprayed with Heprasil. All three scaffold types supported attachment and proliferation of human fetal osteoblasts. However, selective leaching only marginally improved cellular infiltration when compared to meshes obtained by conventional electrospinning. Better cell penetration was seen in mPCL/Col microfibers, and this effect was more pronounced when Heprasil regions were present in the structure. Thus, such techniques could be further exploited for the design of cell permeable fibrous meshes for tissue engineering applications.

Progesteron verstärkt die Differenzierung primärer humaner Osteoblasten in Langzeit-Kulturen

PURPOSE: Following the clinical observation of increased bone loss in perimenopausal women with still adequate serum estrogen levels but progesterone deficiency, long-term cultures of human osteoblasts (HOB) were used to investigate the influence of concentration and cyclicity of progesterone (P) on the proliferation and differentiation of human osteoblasts (HOBs) in the presence or absence of estradiol. MATERIAL AND METHODS: Primary HOBs obtained from non-osteoporotic, perimenopausal women were cultured for 14 and 28 days respectively in medium containing either estradiol at a concentration of 10 −10 M or no estradiol. From day eight on, progesterone (P) was added in concentrations between 10 −6 M and 10 −10 M. The proliferation of HOBs was measured by asssaying hexosaminidase; differentiation was determined by measuring alkaline phosphatase (ALP). RESULTS: Seven days of exposure to physiologic levels of progesterone (6.4 × 10 −7 -10 −9 M) led to a significant increase in ALP concentrations of up to 70 % (p = 0.004 - 0.019), while supraphysiologic progesterone concentration (6.4 × 10 −6 M) showed a significant (50 %) reduction of ALP (p = 0.028). After 21 days of P exposure, ALP increased up to 2.7-fold (p = 0.000 - 0.004) in the physiologic progesterone range, while supraphysiologic concentrations showed a decrease of ALP by 80 % (p = 0.03). This effect was independent of pre- or co-treatment with estradiol. Proliferation was also not significantly affected in the absence of estradiol. CONCLUSION: The effect of progesterone in HOBs from perimenopausal women was dose-dependent for progesterone, independent of estradiol, and reached its peak at concentrations of 10 −9 M progesterone, corresponding to known serum levels in the luteal phase of ovulatory cycles. These results support the concept of an osteoanabolic function of progesterone. Supraphysiologic progesterone concentrations suppressed the differentiation marker ALP in vitro. This could explain the clinical observation of decreased bone density after long-term use of premenopausal depot progestins.

Carbonate substituted hydroxyapatite: Resorption by osteoclasts modifies the osteoblastic response

Carbonate substitution within the hydroxyapatite (HA) lattice improves osteoconduction, although the mechanism by which this occurs is unclear. Discs of dense, sintered, phase-pure HA and AB-type carbonate substituted hydroxyapatite (CHA) were cultured for 21 days with human CD14+ cells in the presence of macrophage-colony stimulating factor (M-CSF) and soluble receptor activator of nuclear factor (NF)-kappaB (sRANKL), during which time osteoclasts developed and resorbed the ceramic surface. Discs were then seeded with human osteoblasts (HOBs), and proliferation and collagen synthesis were measured. On some discs, the conditioned proteinaceous layer left behind by the osteoclasts was preserved. Proliferation of HOBs was increased on resorbed compared to control (unresorbed) surfaces on both materials, provided this osteoclast-conditioned layer was left intact. Collagen synthesis by HOBs was increased on previously resorbed surfaces compared to unresorbed surfaces. This effect was seen on both materials but was seen at an earlier time point on CHA. The results suggest that osteoclasts can condition synthetic bioceramic surfaces and alter the responses of osteoblasts that subsequently populate them. Carbonate substitution may enhance osteoconduction indirectly via effects on enhanced bioresorption.

Surface‐dependent modulation of proliferation, bone matrix molecules, and inflammatory factors in human osteoblasts

Surface properties affect the biological properties of cells modulating the expression of different factors. Osteoblasts contribute both to new bone formation and controlling haematopoiesis through cytokines and growth factors. We analyzed the effect of bone (calcium-phosphate bone slides), cartilaginous (hyaluronan-based scaffold), and plastic substrate culture on human osteoblast proliferation, bone matrix molecule, and inflammatory factor expression. Osteoblast proliferation increased to a greater extent when the cells were grown for 14 days on plastic and bone slides, whereas hyaluronan-based scaffold (HA-scaffold) induced only a minimal increase. Collagen type I, osteonectin, alkaline phosphatase and osteocalcin were expressed on osteoblasts grown on plastic and bone slides and down-modulated at mRNA and protein level by HA-scaffold. Bone slides showed the ability to increase osteopontin mRNA expression. The expression of CXCR4 and CXCL13 was upregulated by bone slides and HA-scaffold, while CXCL12 and CXCR5 expression was down-modulated. These data suggest a substrate-dependent modulation of human osteoblast proliferation, bone matrix and inflammatory factor expression, which might help to understand the active role played by osteoblasts in bone microenvironment by coupling bone extracellular matrix, chemokines and the haematopoietic system.

In vitro response of hFOB cells to pamidronate modified sodium silicate coated cellulose scaffolds

The aim of the present study was to evaluate the suitability of cellulose-based scaffolds coated with pure sodium silicate gel and sodium silicate gels accumulated with different concentrations of the bisphosphonate pamidronate as scaffolds for attachment, proliferation and differentiation of human fetal osteoblasts (hFOB 1.19). Human osteoblasts were cultured in vitro for a period up to 14 days on different cellulose scaffolds. Unmodified and sodium silicate coated cellulose scaffolds were used as control. Two surface-coated modifications of cellulose were applied. The scaffolds were coated in a modified two-step dip coating process with pure sodium silicate gel and pamidronate enriched sodium silicate gel, respectively. In order to investigate the influence of the pamidronate, concentrations of 0.667 mg Na-pamidronate/ml sodium silicate solution, 0.333 mg Na-pamidronate/ml sodium silicate solution and 3.33 × 10 −3 mg Na-pamidronate/ml sodium silicate solution were used for the coating process. Cell proliferation, vitality and attachment were examined by means of cell counting, WST-1 test, fluorescence and scanning electron microscopy. The relative grade of differentiation of hFOB cells was examined by using quantitative real-time polymerase chain reaction (qRT-PCR) analysis for the gene expression of alkaline phosphatase and osteocalcin. Proliferation and differentiation of human osteoblasts was enhanced by the sodium silicate coatings accumulated with pamidronate compared to pure sodium silicate coatings. There was a reciprocal correlation of vitality with the concentration of pamidronate. The highest vitality was found on surfaces with the lowest pamidronate accumulation. Alkaline phosphatase, an early differentiation marker, was overexpressed after 7 days in cells on all pamidronate-containing surfaces (up to 350% compared to untreated cellulose). Osteocalcin, a late differentiation marker, was overexpressed after 14 days in cells on all coated surfaces (up to 300,000% compared to untreated cellulose). The results indicate that due to the modified coating procedure a homogeneous coating and thus, an enhancement of cell attachment and subsequent cellular functions can be achieved. Low concentrations of pamidronate seem to have a relevant effect on cell proliferation and vitality and, therefore, can be recommended for the improvement of the properties of a biomaterial.

Interaction of Galectin-9 With Lipid Rafts Induces Osteoblast Proliferation Through the c-Src/ERK Signaling Pathway

Galectin-9 is a beta-galactoside-binding lectin expressed in various tissues, including bone. The role of galectin-9 in human osteoblasts, however, remains unclear. This study showed that galectin-9 interacts with lipid rafts and induces osteoblast proliferation through the c-Src/ERK signaling pathway. Galectin-9 is a beta-galactoside-binding lectin that modulates many biological functions by interacting with particular carbohydrates attached to proteins and lipids. However, the role of galectin-9 in bone metabolism and osteoblast proliferation remains unclear. This study investigated the effects of galectin-9 on osteoblast proliferation and its signaling mechanisms. The effect of galectin-9 on osteoblast proliferation was tested by measuring the conversion of tetrazolium salt WST-8 to formazan. Protein phosphorylation was assayed by western blotting and confocal microscopy was used to localize lipid rafts. Galectin-9-induced proliferation of the obtained osteoblasts in a dose-dependent manner, whereas galectin-1, -3, and -4 did not. Galectin-9-induced phosphorylation of c-Src and subsequent ERK1/ERK2 in the osteoblasts. The galectin-9-induced phosphorylation and proliferation were inhibited by PP2, a selective inhibitor of c-Src. Galectin-9-induced clustering of lipid rafts detected by cholera toxin B (CTB; binding the raft-resident ganglioside GM1) using confocal microscopy. Cross-linking of the GM1 ganglioside with CTB by anti-CTB antibody-induced phosphorylation of c-Src, whereas disruption of galectin-9-induced lipid rafts by beta-methylcyclodextrin reduced c-Src phosphorylation and proliferation of the cells. These results suggest that galectin-9, but not other galectins, induced proliferation of human osteoblasts through clustering lipid rafts on membrane and subsequent phosphorylation of the c-Src/ERK signaling pathway.

Effects of Activated and Nonactivated Platelet-Rich Plasma on Proliferation of Human Osteoblasts In Vitro

The purpose of this study was to evaluate the effect of progressively increasing concentrations of activated and nonactivated platelet-rich plasma (PRP) on proliferation of human osteoblasts in vitro. Human osteoblasts (hFOB 1.19) obtained from the American Type Culture Collection (ATCC, Manassas, VA) were used in the experiment. PRP was obtained from a 28-year-old healthy male volunteer by means of a Haemonetics gradient density cell separator (Haemonetics, Munich, Germany). Human thrombin was used to activate PRP. Three independent experiments were conducted. Samples containing 10% (0.38x increase in platelet count), 25% (0.95x increase in platelet count), 50% (1.95x increase in platelet count), and 75% (2.86x increase in platelet count) of activated PRP and nonactivated PRP were prepared including controls. After culture periods of 24, 48, and 72 hours osteoblast proliferation was evaluated by counting the number of cells using a Multisizer 3 Coulter Counter (Beckman Coulter, Inc, Fullerton, CA). After 24, 48, and 72 hours of incubation, the number of cells in the control group (without PRP) was higher than that of cells in samples containing activated or nonactivated PRP. Osteoblasts with 10% activated PRP (0.38x increase in platelet count) had the highest viability of all samples containing PRP. Activated PRP resulted in higher proliferation of osteoblasts compared with nonactivated PRP at concentrations of 10% (0.38x increase in platelet count) and 25% (0.95x increase in platelet count) in culture. This study failed to show significant increases in proliferation of human osteoblasts treated with activated or nonactivated PRP compared with controls in vitro.

Potential effects of a low-molecular-weight fucoidan extracted from brown algae on bone biomaterial osteoconductive properties.

In this work, we first tested the influence of low-molecular-weight (LMW) fucoidan extracted from pheophicae cell wall on bidimensional cultured normal human osteoblasts' behaviors. Second, by impregnation procedure with LMW fucoidan of bone biomaterial (Lubboc), we explored in this bone extracellular matrix context its capabilities to support human osteoblastic behavior in 3D culture. In bidimensionnal cultures, we evidenced that LMW fucoidan promotes human osteoblast proliferation and collagen type I expression and favors precocious alkaline phosphatase activity. Furthermore, with LMW fucoidan, von Kossa's staining was positive at 30 days and positive only at 45 days in the absence of LMW fucoidan. In our three-dimensional culture models with the biomaterial pretreated with LMW fucoidan, osteoblasts promptly overgrew the pretreated biomaterial. We also evidenced that osteoblasts increased proliferation with pretreated biomaterial when compared with untreated biomaterial. Osteoblasts secreted osteocalcin and expressed BMP2 receptor on control material as well as with LMW fucoidan impregnated biomaterial. In conclusion, in our experimental conditions, LMW fucoidan stimulated expression of osteoblastic markers differentiation such as alkaline phosphatase activity, collagen type I expression, and mineral deposition; furthermore, cell proliferation was favored. These findings suggest that fucoidan could be clinically useful for bone regeneration and bone substitute design.

Periprosthetic Electrochemical Corrosion of Titanium and Titanium-Based Alloys as a Cause of Spinal Fusion Failure

Posterior lumbar spine implants retrieved from patients affected by periprosthetic osteolysis were analyzed to identify corrosion and to investigate the electromagnetic fields (EMF) generated by corrosion currents and their effect on human osteoblasts proliferation. OBJECTIVE.: Analysis of retrieved instrumentation to better understand periprosthetic osteolysis and correlation of this information with clinical factors. Recent studies have pointed out that mechanically assisted crevice corrosion represents the initial failure of spinal implants, resulting in the local decrease in pH, which leads to osteolysis. Electrochemical analysis was performed to characterize the corrosion currents and the EMF generated around the implants retrieved. Human primary osteoblasts cultures were used to determine the effect of continued EMF stimulation on cell growth. Cultures were exposed to the EMF stimulation for 48 hours, 72 hours, 7 days, and 14 days. During the electrochemical corrosion tests both the screws and the bar showed a passivation current of 0312 and 0.05 muA/cm, respectively. Osteoblasts exposed to an EMF of 12.1 x 10 T displayed a decreased proliferation rate. At each observation time, there were differences in cell numbers between the unexposed cells and the exposed cells. Aseptic periprosthetic bone loss can be due in part to the generation of electric and electromagnetic phenomena generated around metal devices, which inhibit osteoblasts growth and might hamper periprosthetic bone formation. This mechanism is of clinical significance and should be more deeply evaluated.

Nanocrystalline Diamond as a Coating for Joint Implants: Cytotoxicity and Biocompatibility Assessment

Nanocrystalline diamond (NCD) coatings combine a very low surface roughness with the outstanding diamond properties, such as superlative hardness, low self‐friction coefficient, high wear and corrosion resistance, and biotolerance, which are ideal features for applications in medicine (knee and hip replacement) and surgical tools. The present work presents a comprehensive study of the cytotoxicity and biocompatibility of NCD films grown by hot‐filament chemical vapour deposition (HFCVD) technique, aiming such future applications. Cytotoxicity was evaluated in vitro by seeding human gingival fibroblasts on the NCD surface for 14 days, while specific biocompatibility was assessed on samples seeded with human bone marrow‐derived osteoblasts during 21 days. The NCD coatings proved to be noncytotoxic in the preliminary human gingival fibroblast cell cultures, as denoted by a notable sequence of cell attachment, spreading, and proliferation events. In the specific biocompatibility assay envisaging bone tissue applications, NCD coatings induced human osteoblast proliferation and the stimulation of differentiation markers, compared to standard polystyrene tissue culture plates.

Nanocrystalline diamond: In vitro biocompatibility assessment by MG63 and human bone marrow cells cultures

Nanocrystalline diamond (NCD) has a great potential for prosthetic implants coating. Nevertheless, its biocompatibility still has to be better understood. To do so, we employed several materials characterization techniques (SEM, AFM, micro-Raman spectroscopy) and cell culture assays using MG63 osteoblast-like and human bone marrow cells. Biochemical routines (MTT assays, Lowry's method, ALP activity) supported by SEM and confocal microscopy characterization were carried out. We used silicon nitride (Si3N4) substrates for NCD coatings based on a previous demonstration of the superior adhesion and tribological performance of these NCD coated ceramics. Results demonstrate an improved human osteoblast proliferation and the stimulation of differentiated markers, like ALP activity and matrix mineralization, compared with standard polystyrene tissue culture plates. The nanometric featuring of NCD, associated to its chemical affinity are key points for bone regeneration purposes.