Adhesion Of Human Osteoblasts Research Articles

Study on cellular adhesion of human osteoblasts on nano‐structured diamond films

AbstractThe need of new biocompatible materials with superior properties and flexibility in their surface termination and functionalization for medical applications is constantly increasing. Due to the combination of intrinsic properties, chemically deposited diamond thin films are proposed as one of the most promising material in this field. They are chemically/mechanically/physically stable and their surface can be modified by a variety of chemical or plasmatic techniques. In the present work, different diamond nano‐structures, i.e. nano‐rods, ultra nano‐cones and nano‐cones, were prepared by plasma etching process by applying various masking materials (Ni, Au and diamond powder). The impact of these diamond nano‐structures on the growth of human osteoblasts was investigated by fluorescence microscopy. We observed that adhesion of osteoblasts varied, depending upon the diamond nano‐structure as visualized, 1 or 48 h after seeding. Many but very fine focal adhesions are formed on nano‐rods; however, few but large ones are formed on ultra nano‐cones and nano‐cones. The cell adhesion was controlled by the nano‐structuring, thereupon their usage in bio‐medical applications is considered.

Adhesion of human osteoblasts to titanium: A morpho-functional analysis with confocal microscopy

Properties of surface affect the interactions between the implant and osteoblasts and direct the clinical osteointegrative outcome. The aim of this in vitro study was to describe the adhesion of living human osteoblasts to titanium disks with differently prepared surfaces: sand blasted with ZrO 2 particles and acid-etched (Soft-SLA, S-SLA) or with Al 2O 3 particles and acid-etched (Hard-SLA, H-SLA), smooth surface (SS). Confocal microscopy was exploited to follow cell morpho-functional features either on living cells (cell shape with calcein-acethoxymethylester and mitochondria with tetramethylrhodamine methyl ester) or on fixed cells (immunocytochemistry of β1-integrin and of actin) 6 h or 24 h after seeding. The underlying surface was visualized simultaneously on the same field. No cytotoxic effect was detected at any time and on any surface. At 6 h after seeding, osteoblasts showed either a rounded or polygonal shape on both rough surfaces. Several features suggested that adhesion was faster with a higher level of organization on S-SLA than on H-SLA. Indeed osteoblasts grown on S-SLA were wider and with more extended protrusions than those on H-SLA. Active mitochondria on S-SLA occupied perinuclear areas and cellular prolongations, whereas on H-SLA they were mainly focused around nucleus. Organization of integrin β1-subunit and actin, confirmed different kinetics of cell adhesion. At 6 h integrin β1-subunit was distributed along the periphery on the cell-biomaterial focal complexes in cells grown on S-SLA, whereas it was unevenly dispersed in membrane of cells cultured on H-SLA. Stress actin fibers were well defined in cells cultured on S-SLA, whereas they were scarcely evident on H-SLA. Osteoblasts seeded on smooth surface for 6 h had morpho-functional features typical of adhesion, with some elements characterized by an elongated shape with an evident main longitudinal axis. At 24 h osteoblasts were spread-out onto all surfaces. Nonethless, different morphologies were shown in response to the different surfaces tested: polygonal cells prevailed on SLA surfaces, whereas almost all the cells on SS were long with two principal prolongations. At 24 h number of cells adhered to the three kind of surfaces was similar, but during the following three days, cells seeded on S-SLA and on SS proliferated to a greater extent than those cultured on H-SLA. Analysis of morpho-functional parameters performed in living cells, and in particular the study of mitochondria organization, proved to be a valuable tool to follow cell-biomaterial adhesion. A higher level of spreading occurring in osteoblasts grown on S-SLA and SS at early times accounted for a faster subsequent cell proliferation. Nonethless, these comparable activities were exerted by cells showing polygonal or elongated shapes when grown respectively on S-SLA or on SS. The former is typical of osteogenic cells, whereas the latter resumes a fibroblast-like morphology, that would result in an ineffective in vivo osteointegrative process.

Substrate-Induced Assembly of Fibronectin into Networks: Influence of Surface Chemistry and Effect on Osteoblast Adhesion

The influence of surface chemistry-substrates with controlled surface density of -OH groups-on fibronectin (FN) conformation and distribution is directly observed by atomic force microscopy (AFM). FN fibrillogenesis, which is known to be a process triggered by interaction with integrins, is shown in our case to be induced by the substrate (in absence of cells), which is able to enhance FN-FN interactions leading to the formation of a protein network on the material surface. This phenomenon depends both on surface chemistry and protein concentration. The level of the FN fibrillogenesis was quantified by calculating the fractal dimension of the adsorbed protein from image analysis of the AFM results. The total amount of adsorbed FN is obtained by making use of a methodology that employs Western blotting combined with image analysis of the corresponding protein bands, with the lowest sensitivity threshold equal to 15 ng of adsorbed protein. Further, FN adsorption is correlated to human osteoblast adhesion through morphology and actin cytoskeleton formation. Actin polymerization is in need of the formation of the protein network on the substrate's surface. Cell morphology is more rounded (as quantified by calculating the circularity of the cells by image analysis) when the degree of FN fibrillogenesis on the substrate is lower.

Strong influence of hierarchically structured diamond nanotopography on adhesion of human osteoblasts and mesenchymal cells

AbstractWe investigate the influence of different roughnesses (20, 270, and 500 nm) of silicone substrates hermetically coated with the same nanocrystalline diamond (NCD) films on adhesion (1 h) and viability (48 h) of human mesenchymal stromal cells (MSC) and human osteoblasts (SAOS‐2). MSC adhere similarly on all NCD surfaces and control polystyrene (PS), however, their metabolic activity on NCD surfaces is increased. Osteoblasts adhere on NCD in significantly higher numbers than on PS and their adhesion is inversely proportional to increasing substrate roughness. Their metabolic activity is decreased on nano/microrough NCD surfaces in contrast to MSC. The data show that NCD is a suitable biomaterial and can control cell adhesion and growth.

The influence of surface energy on early adherent events of osteoblast on titanium substrates

Surface energy of implant material is one of the important factors in the process of osseointegration. How surface energy regulates the signaling pathway of osteoblasts, however, is not well understood. Cell adhesion is one of the first steps essential to subsequent proliferation and differentiation of bone cells before tissue formation. Our present study was designed to investigate how surface energy may influence the early adhesion of human alveolar osteoblasts (AOBs). Substrates applied were two groups of titanium disks: (1) hydrophobic sandblasted and acid-etched (SLA) surfaces; (2) chemically modified hydrophilic SLA (modSLA) ones. Cell morphology and cell attachment were examined by scanning electron microscopy (SEM). Defined cytoskeletal actin organization was immunohistochemically examined using confocal laser scanning microscopy. RT-PCR was applied to detect and to compare the expression of focal adhesion kinase (FAK) of osteoblasts cultured on the two groups of substrates. The attachment rates of AOBs cultured on modSLA substrates were significantly higher than the cells on SLA ones within 3 h. AOBs on modSLA developed more defined actin stress fibers after 6 h of attachment. FAK expression was comparably higher on modSLA after 6 h. Within the limitation of the current study, higher surface energy of titanium surfaces enhanced the cell adhesion in the early stage of cell response and may work through influencing the expression of adhesion-associated molecules.

Adsorção de fibronectina a arcabouços de polihidroxibutirato aplicáveis à engenharia óssea

Fibronectina sérica humana foi adicionada à superfície de arcabouços de polihidroxibutirato (PHB) a fim de otimizar a adesão de osteoblastos humanos (HOB). Visando a criar sítios para a imobilização de fibronectina (FN), os arcabouços foram previamente tratados por meio de reação com etilenodiamina. O tratamento modificou a morfologia e a composição química dos arcabouços, possibilitando um aumento no teor de FN adsorvido à superfície. Imagens de AFM mostraram que as moléculas de FN assumiram conformações distintas, de acordo com a superfície na qual foi imobilizada. A FN adicionada aos arcabouços não modificados possivelmente assumiu uma conformação estendida, expondo os grupamentos RGD. Com isso, houve um aumento na adesão de HOB a estes materiais. Por outro lado, a FN na superfície dos arcabouços previamente tratados possivelmente apresentou-se na forma compacta, suprimindo a adesão de HOB.

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.

Surface energy of hydroxyapatite and β-tricalcium phosphate ceramics driving serum protein adsorption and osteoblast adhesion

The main objective of this work was to evaluate the specific role of calcium phosphates surface energy on serum protein adsorption and human osteoblast adhesion, by isolating chemical effects from those caused by topography. Highly dense phosphate ceramics (single-phase hydroxyapatite HA and beta-tricalcium phosphates beta-TCP) presenting two distinct nano roughnesses were produced. Some samples were gold-sputter coated in order to conveniently mask the surface chemical effects (without modification of the original roughness) and to study the isolated effect of surface topography on cellular behavior. The results indicated that the nano topography of calcium phosphates strongly affected the protein adsorption process, being more important than surface chemistry. The seeding efficacy of osteoblasts was not affected nor by the topography neither by the calcium phosphate chemistries but the beta-TCP chemistry negatively influenced cell spreading. We observed that surface hydrophobicity is another way to change protein adsorption on surfaces. The decrease of the polar component of surface energy on gold-coated samples leaded to a decreased albumin and fibronectin adsorption but to an increased cell adhesion. Overall, this work contributes to better understand the role of topography and surface chemistry of calcium phosphates in serum protein adsorption and osteoblast adhesion.

Evaluation of Adhesion and Morphology of Human Osteoblasts to White MTA and Portland Cement.

Osteoblasts and periodontal ligament cells are major cells for wound healing after root end resection. The interaction of osteoblasts with filling materials could play a critical role in healing of surgical lesion. Adhesion and spreading of cells on material surface are the initial phase for cellular function. The purpose of the present study was the evaluation of morphology and attachment of human osteoblasts in present of white MTA, Portland cement (PC) and IRM as root end filling and perforation repair materials. The human osteoblasts (MG-63 cell line) were prepared from Iranian Pasteur Institute; Cellular Bank, were grown in RPMI 1640 medium. The testing materials were mixed according to the manufacture's instruction, inserted in to the wells of 24-well flat-bottomed plate, and condensed to disk of 1mm thickness and 1×1mm diameter. Cells were added to the materials after two weeks. During 1,3,7 days intervals, the disk of materials along with cells were grown on their surface, examined by a scanning electron microscope (SEM). We used of IRM as negative group. Results showed that after 7 days many of osteoblasts were attached on the surface of white MTA and PC and appeared partially round or flat. The cells appeared round with no attachment and spreading in conjunction with IRM. The results indicate that human osteoblasts have a favorable response to white MTA and Portland cement compared with IRM.

Adhesion of eukaryotic cells and Staphylococcus aureus to silicon model surfaces

Silicon wafers modified by silanisation with different functional groups are used to study the bioactivity of surfaces with varying physicochemical properties. Oxidation of the wafers created very hydrophilic surfaces, and moderately wettable surfaces were produced by coating with poly(ethylene glycol) (PEG). Immobilization of hydrocarbon chains to the wafers produced hydrophobic surfaces, and hydrophobicity was further increased by fluorocarbon coatings. The oxidized and the hydrocarbon-modified surfaces supported the adhesion of human MG-63 osteoblasts and 3T3 mouse fibroblasts as well as Staphylococcus aureus 8325-4. Adhesion of osteoblasts and fibroblasts, however, was decreased on highly hydrophobic fluorocarbon surfaces, whereas adhesion of S. aureus was supported. Coating of the fluorocarbon surface with fibronectin increased the number of attached eukaryotic cells, but the accumulation of bacteria remained unchanged. In contrast, surface coatings with PEG-groups inhibited the binding of S. aureus; however, the adhesion of the eukaryotic cells was high. The number of S. aureus on PEG-modified surfaces covered with fibronectin increased about twofold, yet it was still decreased to 25-30% related to the number of bacteria on other surfaces. These findings provide evidence that the PEG-modified surfaces showed selective bioactivity, preventing the attachment of a microbial pathogen but supporting the adhesion of eukaryotic cells.

The effects of nanoscale pits on primary human osteoblast adhesion formation and cellular spreading

Current understanding of the mechanisms involved in ossesoinegration following implantation of a biomaterial has led to an emphasis being placed on the modification of material topography to control interface reactions. Recent studies have inferred nanoscale topography as an important mediator of cell adhesion and differentiation. Biomimetic strategies in orthopaedic research aim to exploit these influences to regulate cellular adhesion and subsequent bony tissue formation. Here experimental topographies of nanoscale pits demonstrating varying order have been fabricated by electron-beam lithography in (poly)carbonate. Osteoblast adhesion to these nanotopographies was ascertained by quantification of the relation between adhesion complex formation and total cell area. This study is specifically concerned with the effects these nanotopographies have on adhesion formation in S-phase osteoblasts as identified by BrdU incorporation. Nanopits were found to reduce cellular spreading and adhesion formation.

TGF‐β1 calcium signaling in osteoblasts

Transforming growth factor-beta1 (TGF-beta1) action is known to be initiated by its binding to multiple cell surface receptors containing serine/threonine kinase domains that act to stimulate a cascade of signaling events in a variety of cell types. We have previously shown that TGF-beta1 and BMP-2 treatment of primary human osteoblasts (HOBs) enhances cell-substrate adhesion. In this report, we demonstrate that TGF-beta1 elicits a rapid, transient, and oscillatory rise in the intracellular Ca(2+) concentration, [Ca(2+)](i), that is necessary for enhancement of cell adhesion in HOBs but does not alter the phosphorylation state of Smad proteins. This rise in [Ca(2+)](i) in HOB is not observed in the absence of extracellular calcium or when the cells are treated with the L-type Ca(2+) channel blocker, nifedipine, but is stimulated upon treatment with the L-type Ca(2+) channel agonist, Bay K 8644, or under high K(+) conditions. The rise in [Ca(2+)](i) is severely attenuated after treatment of the cells with thapsigargin, a selective endoplasmic reticulum Ca(2+) pump inhibitor. TGF-beta1 enhancement of HOB adhesion to tissue culture polystyrene is also inhibited in cells treated with nifedipine. These data suggest that intracellular Ca(2+) signaling is an important second messenger of the TGF-beta1 signal transduction pathway in osteoblast function.

Regulation of implant surface cell adhesion: characterization and quantification of S‐phase primary osteoblast adhesions on biomimetic nanoscale substrates

Integration of an orthopedic prosthesis for bone repair must be associated with osseointegration and implant fixation, an ideal that can be approached via topographical modification of the implant/bone interface. It is thought that osteoblasts use cellular extensions to gather spatial information of the topographical surroundings prior to adhesion formation and cellular flattening. Focal adhesions (FAs) are dynamic structures associated with the actin cytoskeleton that form adhesion plaques of clustered integrin receptors that function in coupling the cell cytoskeleton to the extracellular matrix (ECM). FAs contain structural and signalling molecules crucial to cell adhesion and survival. To investigate the effects of ordered nanotopographies on osteoblast adhesion formation, primary human osteoblasts (HOBs) were cultured on experimental substrates possessing a defined array of nanoscale pits. Nickel shims of controlled nanopit dimension and configuration were fabricated by electron beam lithography and transferred to polycarbonate (PC) discs via injection molding. Nanopits measuring 120 nm diameter and 100 nm in depth with 300 nm center-center spacing were fabricated in three unique geometric conformations: square, hexagonal, and near-square (300 nm spaced pits in square pattern, but with +/-50 nm disorder). Immunofluorescent labeling of vinculin allowed HOB adhesion complexes to be visualized and quantified by image software. Perhipheral adhesions as well as those within the perinuclear region were observed, and adhesion length and number were seen to vary on nanopit substrates relative to smooth PC. S-phase cells on experimental substrates were identified with bromodeoxyuridine (BrdU) immunofluorescent detection, allowing adhesion quantification to be conducted on a uniform flattened population of cells within the S-phase of the cell cycle. Findings of this study demonstrate the disruptive effects of ordered nanopits on adhesion formation and the role the conformation of nanofeatures plays in modulating these effects. Highly ordered arrays of nanopits resulted in decreased adhesion formation and a reduction in adhesion length, while introducing a degree of controlled disorder present in near-square arrays, was shown to increase focal adhesion formation and size. HOBs were also shown to be affected morphologicaly by the presence and conformation of nanopits. Ordered arrays affected cellular spreading, and induced an elongated cellular phenotype, indicative of increased motility, while near-square nanopit symmetries induced HOB spreading. It is postulated that nanopits affect osteoblast-substrate adhesion by directly or indirectly affecting adhesion complex formation, a phenomenon dependent on nanopit dimension and conformation.

Effect of a gold–palladium coating on the long-term adhesion of human osteoblasts on biocompatible metallic materials

Our ambition for several years is to study the in vitro interface between human bone cells and biomedical metals in order to improve dental and orthopaedic implant's surface. The long-term adhesion of human osteoblasts cultured on pure titanium, titanium alloy and stainless steel substrates presenting 4 different surface morphologies and 2 different roughness amplitudes (obtained by sand-blasting, acid-etching, electro-erosion and polishing) was quantified from 24 h to 21 days. The half part of the samples was sputter-coated with gold–palladium. The coating by a nanometric gold–palladium layer influenced differently the long-term adhesion of human osteoblasts as a function of the composition of the substrate. This influence was either positive, neutral or negative but was significantly demonstrated only three times. In all the three cases, the coating improved the long-term adhesion of osteoblasts. Consequently, it appears that a gold–palladium coating could be a good way to improve cell adhesion, and perhaps tissue adhesion, on metallic surfaces with low biocompatibility like polished stainless steel substrates or acid-etched pure titanium substrates.

Interaction of human osteoblasts with bioinert and bioactive ceramic substrates

The objective of this study was to compare adhesion, replication, and differentiation of human osteoblasts (OPC1 cell line) on two different ceramic substrates: a bioinert alumina (A1(2)O(3)), and a bioactive hydroxyapatite (HAp). Scanning electron microscopy (SEM) and confocal scanning microscopy were used to assess production and distribution of specific osteoblast proteins. Cells grew readily on HAp and alumina. On alumina and HAp, OPC1 cells produced distinctive cell-to-cell and cell-to-scaffold filopodia and microextensions. OPC1 cells proliferated faster on HAp than on alumina substrates. Adhesion was further assessed by observing production of the protein vinculin. On alumina, vinculin was detected throughout the cytoplasm, with some peripheral punctate regions. On HAp, OPC1 cells developed few punctate peripheral regions of vinculin; rather, the protein was strongly localized within the cytoplasm. Finally, we measured accumulation of the marker osteopontin (OPN). OPN was first detectable on day 5 and increased through day 11 of culture on alumina. OPC1 cells on HAp produced substantial amounts of OPN beginning at day 5, with apparent secretion from the cells by culture day 11. These results suggest that the function of osteoblasts is strongly affected by the properties of ceramic surfaces, and rapid attachment of osteoblasts may result in earlier differentiation on HAp than on alumina.

αvβ Integrins Play an Essential Role in BMP-2 Induction of Osteoblast Differentiation

Both integrins and BMP-2 exert similar effects on osteoblasts. We examined the relationship between the alphav-containing integrins (alphavbeta) and BMP-2 in osteoblast function. BMP-2 stimulates alphavbeta expression. BMP-2 receptors co-localize/overlap with alphavbeta integrins, and the intact function of alphavbeta is essential in BMP-2 activity. Bone morphogenetic protein (BMP)-2 not only induces osteoblast differentiation and bone matrix mineralization, but also stimulates osteoblast migration on and adhesion to bone matrix proteins. The alphavbeta- and beta1- (alphabeta1) containing integrins mediate osteoblast interaction with many bone matrix proteins and play important roles in osteoblast adhesion, migration, and differentiation. Because alphavbeta integrins and BMP-2 share common effects on osteoblasts, we analyzed their relationship in osteoblast function. The effects of BMP-2 on integrin expression were determined by surface labeling/immunoprecipitation and cell adhesion to matrix proteins. Confocal analysis of the immunostained cells and co-immunoprecipitation of cell extracts were used to study the spatial relationship between integrins and BMP-2 receptors. A function-blocking anti-alphavbeta integrin antibody (L230) was employed to investigate the roles of alphavbeta integrins in BMP-2 function. Human osteoblasts (HOBs) express alphabeta1, alphavbeta3, alphavbeta5, alphavbeta6, and alphavbeta8 integrins at focal adhesion sites. BMP-2 increases the levels of these integrins on osteoblast surface and enhances HOB adhesion to osteopontin and vitronectin. Immunoprecipitation and immunostaining analyses show that BMP-2 receptors co-localize or overlap with alphavbeta and alphabeta1 integrins. Incubation of HOBs with L230 abolishes the antiproliferative effect of BMP-2 and reduces the capacity of BMP-2 to stimulate alkaline phosphatase activity and the expression of osteocalcin, osteopontin, and bone sialoprotein. Furthermore, L230 prevents BMP-2 induction of matrix mineralization. Although BMP-2 retains its receptor-binding capability in the presence of L230, BMP-2 stimulation of Smad signaling is abolished by L230. BMP-2 upregulates the expression of alphavbeta integrins, and these integrins, in turn, play a critical role in BMP-2 function in osteoblasts.

Topography effects of pure titanium substrates on human osteoblast long-term adhesion

Classically various treatments are applied to increase the roughness of titanium implants and improve their integration in the tissues. Many in vitro studies have been performed to better understand the mechanisms underlying the adhesion of cells on materials. Frequently, the adhesion is related to the attachment of cells during the first hours of contact with the substrate. For several years, our objective has been to develop experimental methods to evaluate the long-term adhesion of human osteoblasts from some hours to several weeks in order to model in vitro a tissue-like interface. This culture model allows for the formation over 21 days of a complex osteoblast/extracellular matrix/material interface. We recently developed a new parameter called adhesion power (AP) to evaluate this long-term adhesion. In this study, our objective is to check its efficiency in discriminating the long-term adhesion of human osteoblasts on pure titanium substrates with seven different surface morphologies obtained by electro-erosion, sandblasting, polishing, acid-etching and machine-tooling. By scanning electron microscopy, we observed that the human osteoblasts did spread more intimately on surface with low roughness amplitude than on rough ones. However, the AP was higher on rough isotropic surfaces obtained by electro-erosion, sandblasting or acid-etching and lower on smoother surfaces obtained by polishing and machine-tooling. We demonstrated that the AP was pertinent for evaluating human osteoblast’s long-term adhesion on pure titanium surfaces with various roughness parameters. Its correlation with the order parameter, which describes the organization of the roughness, confirmed once more that human osteoblasts are more sensitive to the organization and morphology of the roughness than to its amplitude.

Statistical correlation between cell adhesion and proliferation on biocompatible metallic materials

Our ambition for several years is to appreciate and quantify the long-term adhesion of cells on materials at times where the interface between cells and substrate becomes more complex, more closed to the cell/matrix/substrate interface existing in vivo. With this objective, we quantified the long-term adhesion and proliferation of human osteoblasts cultured from 24 h to 21 days on pure titanium, titanium alloy, and stainless-steel substrates presenting six different surface morphologies and two different roughness amplitude. Hence, we did proceed to the statistical correlation of cell adhesion and cell proliferation on 30 different substrates. Additionally, we described surface topography not only by the roughness amplitude but also by the roughness morphology using new specific parameters. By multiple analysis of variance, we demonstrated that nor material composition nor surface roughness amplitude did influence cell proliferation, whereas a very significant influence of the process used to produce the surface was observed meaning that the main influent factor on cell proliferation was the surface morphology. The long-term adhesion and proliferation capacity of cells were positively correlated on 23 types of substrates on 30, this positive correlation being statistically asserted on 13 types of substrates on 23. This study is the first demonstration of the existence of a statistical correlation between long-term adhesion and proliferation capacity of human bone cells on substrates with various chemical composition, surface chemistry, and surface topography.

Porous titanium obtained by a new powder metallurgy technique: Preliminary results of human osteoblast adhesion on surface polished substrates

This study concerns a novel powder metallurgy method for producing porous titanium (pTi) exhibiting high mechanical properties. The preparation procedure consisted of the following stages: first, the preparation of Ti and titanium hydride (TiH2) powder mixtures and their consolidation with a cold isostatic press, followed by a sintering of the green bodies performed with hot isostatic press (HIP) equipment. Thermal decomposition in controlled environment of the TiH2 phase results in the foam structure. The resulting porosity percolates with a volume fraction of approximately 20%. The final material exhibits interesting mechanical properties, comparable to those of full density titanium (between grade 2 and grade 3), with the advantage of a minor density. The samples produced were tested to verify their biological response by studying the effectiveness of osteoblast adhesion and growth. In this preliminary study, osteoblastic cell morphology was investigated and compared to that observed on fully dense commercially pure titanium (Ti-cp) (ASTM, grade 3). The preliminary results were promising regarding cellular adhesion and spreading. (Journal of Applied Biomaterials & Biomechanics 2003; 1: 172-7).