Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0265264 (HOS)
 1,119 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hydroxyapatite (HA) is a bioactive dental implant material which accelerates bone formation on its surface. The mechanism of this acceleration is not clear. The elucidation of the cell adhesion might be the key to the understanding of the bioactive mechanism of HA. In this study, we analyzed the adhesion of HOS human osteoblasts onto HA and titanium to find the particular adhesion to HA. In short-term cultures in fetal bovine serum-pre-coated materials, a significantly higher number of cells adhered to HA than to titanium. In addition, serum-free conditions with phosphate-buffered saline pre-coating or bovine serum albumin pre-coating materials were tested. The results were nearly the same among all pre-coating conditions, suggesting that the quantity of cell adhesion was not affected by serum components. However, in the morphological observations by SEM, the form of adhesion was found to differ among pre-coating conditions. The osteoblasts tightly adhered and spread onto both HA and titanium with serum pre-coating, whereas the cells loosely adhered and did not spread without serum. To evaluate the Arg-Gly-Asp (RGD) sequence-specific adhesion, we used synthetic RGD peptides for a competitive inhibition test. The results showed that RGD peptides remarkably inhibited the tight adhesion and spreading of osteoblasts onto HA, whereas they did not strongly inhibit adhesion and spreading onto titanium. These results demonstrate that the regulation of cell adhesion to HA is different from that to titanium. Our study suggests that the RGD-containing serum proteins might have a major role in regulating the specific adhesion of osteoblasts to HA, and in inducing enhanced cell growth and differentiation.
 ...
PMID:RGD peptides regulate the specific adhesion scheme of osteoblasts to hydroxyapatite but not to titanium. 949 21

Periprosthetic osteolysis is a major cause of aseptic loosening in artificial joint replacement. It is assumed to occur in conjunction with the activation of macrophages. We have shown in vitro that human osteoblast-like cells, isolated from bone specimens obtained from patients undergoing hip replacement, phagocytose fine particles of titanium alloy (TiAlV). The human osteoblast-like cells were identified immunocytochemically by the presence of bone-specific alkaline phosphatase (BAP). With increasing duration of culture, a variable number of the osteoblastic cells became positive for the macrophage marker CD68, independent of the phagocytosis of particles, with a fine granular cytoplasmic staining which was coexpressed with BAP as revealed by immunodoublestaining. The metal particles were not toxic to the osteoblastic cells since even in culture for up to four weeks massively laden cells were vital and had a characteristic morphology. Cells of the human osteosarcoma cell line (HOS 58) were also able to phagocytose metal particles but had only a low expression of the CD68 antigen. Fluorescence-activated cell scanning confirmed our immunocytochemical results. Additionally, the cells were found to be negative for the major histocompatibility complex-II (MHC-II) which is a marker for macrophages and other antigen-presenting cells. Negative results of histochemical tests for tartrate-resistant acid phosphatase excluded the contamination by osteoclasts or macrophages in culture. Our observations suggest that the osteoblast can either change to a phagocytosing cell or that the phagocytosis is an underestimated property of the osteoblast. The detection of the CD68 antigen is insufficient to prove the monocytic lineage. In order to discriminate between macrophages and osteoblasts additional markers should be used. To our knowledge, this is the first demonstration of cells of an osteoblastic origin which have acquired a mixed phenotype of both osteoblasts and macrophages.
 ...
PMID:Human osteoblast-like cells phagocytose metal particles and express the macrophage marker CD68 in vitro. 1075 42

Hydroxyapatite (HA) is an osteoconductive implant material. We previously demonstrated that RGD peptides regulate the spreading of HOS cells on HA but not on titanium, speculating that the osteoconductivity of HA might be attributed to this RGD domain-dependent spreading of osteoblasts. To confirm this hypothesis, the molecules which regulate the spreading of HOS cells on HA and on titanium were investigated. The 50% effective dose (ED50) of RGD peptide for the spreading on HA was five fold lower comparing to titanium. Anti-alphaV integrin antibody, vitronectin, and fibronectin inhibited the spreading on HA but not on titanium. In Western blot analysis, vitronectin and fibronectin were found in components adsorbed to HA but not to titanium. Taken together, the spreading of HOS cells on HA but not on titanium requires the interaction of alphaV integrin and its ligands. The ED50 of the RGD peptides on titanium but not on HA was remarkably reduced by neuraminidase treatment, that by itself could not inhibit the spreading on both materials. This phenomenon suggests that RGD domain and sialic acid cooperatively but not independently mediate the spreading of HOS cells on titanium. Collectively, the molecules regulating the spreading on HA are apparently different from those on titanium. The spreading of osteoblasts mediated by RGD domain of vitronectin and fibronectin might contribute to the osteoconductive ability of HA.
 ...
PMID:Diverse mechanisms of osteoblast spreading on hydroxyapatite and titanium. 1081 64

Titanium (Ti) surface was coated with hydroxyapatite (HA) films via the sol-gel method. The coating properties, such as crystallinity and surface roughness, were controlled and their effects on the osteoblast-like cell responses were investigated. The film crystallinity was controlled with different heat treatment temperatures (400, 500, and 600 degrees C): Also the surface roughness was changed by using different heating rates (1 and 50 degrees C/min). The obtained sol-gel films had a dense and homogeneous structure with a thickness about 1 mum. The film heat-treated at higher temperature had enhanced crystallinity (600>500>>400 degrees C), while retaining similar surface roughness. When heat-treated rapidly (50 degrees C/min), the film became quite rough, with roughness parameters being much higher (4-6 times) than that obtained at a low heating rate (1 degrees C/min). The dissolution rate of the film decreased with increasing crystallinity (400>>500>600 degrees C), and the rougher film had slightly higher dissolution rate. The attachment, proliferation, and differentiation behaviors of human osteosarcoma HOS TE85 cells were affected by the properties of the films. On the films with higher crystallinity (heat treated over 500 degrees C), the cells attached and proliferated well and expressed alkaline phosphatase (ALP) and osteocalcin (OC) to a higher degree as compared to the poorly crystallized film (heat treated at 400 degrees C). On the rough film, the cell attachment was enhanced, but the ALP and OC expression levels were similar as compared to the smooth films.
 ...
PMID:Sol-gel-modified titanium with hydroxyapatite thin films and effect on osteoblast-like cell responses. 1601 54

Biocompatibility is a pre-requisite for all biomaterials used for medical application. During the last two decades significant advances have been made in the development of novel materials and selection and use of these materials has been directly dependent upon their biocompatibility. Several materials containing calcium or titanium cations demonstrate biocompatibility and are routinely used in various forms within the human body. Due to its position in the periodic table, scandium in the form of its oxide scandia (Sc(2)O(3)) was studied as the first stage of a wider exploration of the biocompatibility of ceramics. A commercial human osteoblast-like cell line (HOS TE 85) was used to study the biocompatibility of both sintered and abraded scandia surfaces. Scanning electron microscopy was used to examine cell adhesion, the MTT assay was used to measure cell metabolic function and the alamarBlue for the assessment of proliferation. Although the results are only preliminary findings, qualitative observations showed that both sintered and abraded surfaces favoured cell adhesion to the same extent. Quantitatively, a significant increase in cell proliferation was observed on Sc(2)O(3) compared to Thermanox, tissue culture control. Furthermore, Sc(2)O(3) has been shown to be non-toxic, able to be maintain cell viability and support cell growth and proliferation.
 ...
PMID:Scandia--a potential biomaterial? 1638 87

Hydroxyapatite (Ca10 (PO4)6(OH)2, HAP), a multimineral substituted calcium phosphate is one of the most substantial bone mineral component that has been widely used as bone replacement materials because of its bioactive and biocompatible properties. However, the use of HAP as bone implants is restricted due to its brittle nature and poor mechanical properties. To overcome this defect and to generate suitable bone implant material, HAP is combined with biodegradable polymer (polycaprolactone, PCL). To enhance the mechanical property of the composite, carbon nanofibers (CNF) is incorporated to the composite, which has long been considered for hard and soft tissue implant due to its exceptional mechanical and structural properties. It is well-known that nanofibrous scaffold are the most-prominent material for the bone reconstruction. We have developed a new remarkable CNF/PCL/mineralized hydroxyapatite (M-HAP) nanofibrous scaffolds on titanium (Ti). The as-developed coatings were characterized by various techniques. The results indicate the formation and homogeneous distribution of components in the nanofibrous scaffolds. Incorporation of CNF into the PCL/M-HAP composite significantly improves the adhesion strength and elastic modulus of the scaffolds. Furthermore, the responses of human osteosarcoma (HOS MG63) cells cultured onto the scaffolds demonstrate that the viability of cells were considerably high for CNF-incorporated PCL/M-HAP than for PCL/M-HAP. In vivo analysis show the presence of soft fibrous tissue growth without any significant inflammatory signs, which suggests that incorporated CNF did not counteract the favorable biological roles of HAP. For load-bearing applications, research in various bone models is needed to substantiate the clinical availability. Thus, from the obtained results, we suggest that CNF/PCL/M-HAP nanofibrous scaffolds can be considered as potential candidates for orthopedic applications.
 ...
PMID:Carbon Nanofiber/Polycaprolactone/Mineralized Hydroxyapatite Nanofibrous Scaffolds for Potential Orthopedic Applications. 2812 19

In this study, we evaluated early bone responses to a vitronectin-derived, minimal core bioactive peptide, RVYFFKGKQYWE motif (VnP-16), both in vitro and in vivo, when the peptide was treated on sandblasted, large-grit, acid-etched (SLA) titanium surfaces. Four surface types of titanium discs and of titanium screw-shaped implants were prepared: control, SLA, scrambled peptide-treated, and VnP-16-treated surfaces. Cellular responses, such as attachment, spreading, migration, and viability of human osteoblast-like HOS and MG63 cells were evaluated in vitro on the titanium discs. Using the rabbit tibia model with the split plot design, the implants were inserted into the tibiae of four New Zealand white rabbits. After two weeks of implant insertion, the rabbits were sacrificed, the undecalcified specimens were prepared for light microscopy, and the histomorphometric data were measured. Analysis of variance tests were used for the quantitative evaluations in this study. VnP-16 was non-cytotoxic and promoted attachment and spreading of the human osteoblast-like cells. The VnP-16-treated SLA implants showed no antigenic activities at the interfaces between the bones and the implants and indicated excellent bone-to-implant contact ratios, the means of which were significantly higher than those in the SP-treated implants. VnP-16 reinforces the osteogenic potential of the SLA titanium dental implant.
 ...
PMID:A Vitronectin-Derived Bioactive Peptide Improves Bone Healing Capacity of SLA Titanium Surfaces. 3162 47