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Query: UMLS:C0265264 (HOS)
 1,119 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The osteogenic potential of the two human osteosarcoma cell lines HOS and KHOS; a cell line produced by the transformation of the HOS cells by the Kirsten murine sarcoma virus, was studied in vitro. HOS cells cultured more than 2 weeks formed nodules composed of two morphologically distinct layers, an epithelial-like surface cell layer and a collagen-rich inner cell layer. Alkaline phosphatase (ALPase) activity occurred in the plasma membrane of the surface cell layer, and calcified substances developing along collagen fibers were detected in the collagen-rich inner cell layer. The calcified substances were further examined by analytical electron microscopy and were shown to be hydroxyapatite crystals. In contrast, there was neither ALPase nor the deposition of a calcified substance in the KHOS cells.
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PMID:In vitro differentiation of the human osteosarcoma cell lines, HOS and KHOS. 135 21

The contraction of floating collagen gels is suggested to mimic the reorganization of collagenous matrix during development and tissue healing. Here, we have studied two osteogenic cell lines, namely MG-63 and HOS, and a chemically transformed subclone of HOS cells, HOS-MNNG. Transforming growth factor-beta (TGF-beta), a putative regulator of bone fracture healing, increased collagen gel contraction by MG-63 and HOS-MNNG, but not by HOS cells. Our data show that TGF-beta-induced fibronectin synthesis is not sufficient for the process. Instead, anti-beta 1 integrin antibodies could prevent the contraction. There are three different integrin heterodimers that are known to mediate the cell-collagen interaction, namely alpha 1 beta 1, alpha 2 beta 1, and alpha 3 beta 1. In MG-63 cells TGF-beta increased the expression of alpha 2 beta 1 integrin and decreased the expression of alpha 3 beta 1 integrin, whereas alpha 1 beta 1 integrin is not expressed. HOS cells had no alpha 2 beta 1 integrin, neither did TGF-beta induce its expression. However, HOS-MNNG cells expressed more alpha 2 beta 1 integrin when treated with TGF-beta. Thus, we suggest that the mechanism of the enhanced collagen gel contraction by TGF-beta is the increased expression of alpha 2 beta 1 integrin heterodimer. To further test this hypothesis, we expressed a full-length alpha 2 integrin cDNA in HOS cells and in MG-63 cells. We obtained HOS cell clones that expressed alpha 2 beta 1 heterodimer, and the ability of these cells to contract collagen gels was greatly enhanced. Furthermore, the contraction by MG-63 cells transfected with alpha 2 integrin cDNA was enhanced, and the contraction by cells transfected with antisense oriented alpha 2 integrin cDNA was decreased. Thus, both in MG-63 and HOS cells the increased alpha 2 integrin expression alone was sufficient for the enhanced contraction of collagen gels. Furthermore, the amount of alpha 2 integrin is critical for the process, and its decrease leads to diminished ability to contract gels.
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PMID:Transforming growth factor-beta regulates collagen gel contraction by increasing alpha 2 beta 1 integrin expression in osteogenic cells. 752 33

A classical model for studying the effects of extracellular matrix is to culture cells inside a three-dimensional collagen gel. When surrounded by fibrillar collagen, many cell types decrease the production of type I collagen, and the expression of interstitial collagenase (matrix metalloproteinase-1; MMP-1) is simultaneously induced. To study the role of the collagen-binding integrins alpha 1 beta 1 and alpha 2 beta 1 in this process, we used three different osteogenic cell lines with distinct patterns of putative collagen receptors: HOS cells, which express only alpha 1 beta 1 integrin, MG-63 cells, which express only alpha 2 beta 1 integrin, and KHOS-240 cells, which express both. Inside collagen gels, alpha 1 (I) collagen mRNA levels were decreased in HOS and KHOS-240 cells but not in MG-63 cells. In contrast, MMP-1 expression was induced in KHOS-240 and MG-63 cells but not in HOS cells. Transfection of MG-63 cells with alpha 2 integrin cDNA in an antisense orientation reduced the expression level of alpha 2 integrin. These cell clones showed induction and reduction of mRNA levels for MMP-1, respectively. HOS cells normally lacking alpha 2 beta 1 integrin were forced to express it, and this prevented the down-regulation in the levels of alpha 1 (I) collagen mRNA when cells were grown inside collagen gels. The data indicate that the level of MMP-1 expression is regulated by the collagen receptor alpha 2 beta 1 integrin. The down-regulation of collagen alpha 1 (I) is mediated by another receptor. Integrin alpha 2 beta 1 may compete with it and thus be a positive regulator of collagen synthesis.
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PMID:Integrin alpha 2 beta 1 is a positive regulator of collagenase (MMP-1) and collagen alpha 1(I) gene expression. 776 57

Bone morphogenetic proteins (BMPs) are members to the transforming growth factor-beta superfamily. They induce ectopic bone formation in rat and are pleiotropic initiators of inducible osteogenic precursor cells. A lot of reports have studied the presence of BMPs and their effects on bone marker expression in many different cell lines, however none describe the regulation of BMP3 by different factors and expression conditions. When a human bone marrow stromal cell (HBMSC) culture was treated simultaneously with 1,25(OH)2D3 (10(-8) M) and BMP3 (2.5 ng/ml), the total osteocalcin content in the cell layer and in the culture medium was higher than when the culture was treated with either factor alone (162%). To elucidate this synergistic activity, Northern blot analysis was done to study the effect of 1,25(OH)2D3 on BMP3 mRNA expression. Several human cell lines (MNNG, U-2OS, MG-63, KHOS, TE85, HOS) and HBMSC were treated by 1,25(OH)2D3 (10(-8) M for 24 h). Purified mRNA from treated and untreated cells were denatured using glyoxal and dimethylsulfoxide, and were fractionated on a 1% agarose gel. After electrophoresis, RNA were blotted onto a nylon membrane and incubated with 32P-labeled BMP3 and GAPDH riboprobes. Northern blot analysis revealed that, the BMP3 mRNA level was increased in a few cell lines (MG-63, HBMSC, HOS) after the addition of 1,25(OH)2D3 when compared to the untreated cells (127%+/-1; 130.5%+/-19.5; 207%+/-14). An higher stimulation was observed in HBMSC primary culture when compared to differentiated HBMSC. In view of these results, we now investigate the following hypothesis: does the BMP3 promoter exhibit the vitamin D receptor response like the osteocalcin gene?
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PMID:Effect of 1,25(OH)2D3 on bone morphogenetic protein-3 mRNA expression. 1008 19

An osteoblastic cell line (HOS cells) produces a prominent osteoid matrix with mineralization. Fibroblasts, on the other hand, do not exhibit this mineralization. To evaluate the degree of mineralization, we added calcein to the culture medium and then observed the culture wells by using an image analyzer. The calcein uptake into the cell/matrix layer was detected in the HOS cells but not in the fibroblasts. The calcein uptake was also quantified in situ by using an image analyzer, which revealed high levels in the HOS cells, which correlated well with the calcium content of the mineralized matrix. Rat marrow cells were also cultured in media containing calcein, fetal bovine serum, beta-glycerophosphate, L-ascorbic acid 2-phosphate, and with or without dexamethasone. With the dexamethasone, the cells exhibited osteogenic differentiation that resulted in mineralized matrix formation after about 10 days. The matrix formation coincided with the appearance of calcein uptake into the cell/matrix layer, with the amount of calcein uptake increasing with time. By contrast, the culture without the dexamethasone did not exhibit matrix formation and the calcein uptake was negligible. In the case of both HOS cell and rat marrow cell cultures in vitro, calcein did not affect expressions of their alkaline phosphatase activity or osteocalcin production. Furthermore, histologic observation revealed that rat marrow cells subcultured with calcein could show osteogenic ability after in vivo implantation. These results suggest that the current method of detecting calcein uptake in a culture allows the monitoring of the osteogenic capacity of cultured cells, as well as the measurement of the amount of mineralization produced by the osteogenic cells. Given that osteogenic cultured cells/mineralized matrices are used in bone reconstruction surgery, the in situ monitoring method is invaluable in that it allows us to evaluate the osteogenic capacity of in vitro constructs.
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PMID:In-situ visualization and quantification of mineralization of cultured osteogenetic cells. 1295 91

Bone morphogenetic protein-6 (BMP-6) is a potent inducer of osteogenic differentiation and its expression is stimulated by 17beta-estradiol. The existence of a regulatory loop between sex steroids and BMP-6 is therefore reasonable to hypothesize. Here we determined whether the sex steroids 17beta-estradiol and dihydrotestosterone, and the phytoestrogen resveratrol can modulate BMP-6-induced alkaline phosphatase activity and osteocalcin expression. Mesenchymal cells of murine (osteoblastic MC3T3-E1 cells, preadipogenic ST2 cells, prechondrogenic ATDC5 cell) and human origin (osteosarcoma SaOS and HOS cells, primary bone marrow stromal cells) were cultured in the presence of recombinant BMP-6 under serum-free conditions. BMP-6 dose-, and time-dependently increased alkaline phosphatase activity in murine cell lines, but not in human cells. Osteocalcin expression was also increased upon stimulation with BMP-6. The presence of 17beta-estradiol, dihydrotestosterone, and resveratrol had no effect on BMP-6-induced alkaline phosphatase activity and osteocalcin expression. These data suggest that osteogenic differentiation in response to BMP-6 occurs independent of steroid hormones and resveratrol in mesenchymal cells that express basal receptor levels.
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PMID:BMP-6-induced osteogenic differentiation of mesenchymal cell lines is not modulated by sex steroids and resveratrol. 1296 49

The cells in bone grow on a composite matrix made up of mineral and organic (mainly type-I collagen) components. In this study, anorganic bone mineral (ABM) particles were coated with a cell-binding domain of type-I collagen (P-15 peptide) to mimic the bone matrix components and suspended in injectable hyaluronate (Hy) hydrogels. The ABM/P-15/Hy was compared to ABM/Hy-the same matrix without P-15 peptide. Osteoblast-like HOS cells migrated through the hydrogels around ABM/P-15 or ABM particles; however, more cells adhered to ABM/P-15/Hy particles, and the cells formed better surface coverage and had more stress fibers on ABM/P-15/Hy. HOS cells cultured on ABM/P-15/Hy had increased osteogenic gene expression for alkaline phosphatase and bone morphogenetic proteins, and deposited more mineralized matrix. Studies with two different hydrogels (carboxymethylcellulose and sodium alginate) showed similar enhanced cell attachment and mineralization. The studies suggest that the ABM/P-15 in hydrogels can be used as an injectable biomimetic matrix to facilitate bone repair.
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PMID:Enhanced cell attachment and osteoblastic activity by P-15 peptide-coated matrix in hydrogels. 1457 11

In this article we describe the expansion of in vitro osteogenic capability of human osteoblasts (HOS cells) after sorting by fluorescence-activated cell sorting (FACS) with the osteoblastic marker of human bone alkaline phosphatase (AP) monoclonal antibody. After culturing for 7 days, the HOS cells were incubated with fluorescein isothiocyanate (FITC)-labeled AP monoclonal antibody. The antibody recognized the cells with high AP activity (high AP cells), which were about 76% of the total cells. After the HOS cells were sorted, the high AP cells could be recovered, and almost all of them reacted strongly with the AP antibody. Therefore, we were able to condense the high AP cells about 1.3 times. We further cultured the sorted cells as well as the unsorted control cells. After the initial seeding, the culturing periods for both groups of cells were 20 days. At the end of this period, we measured AP activity per DNA and osteocalcin contents. In contrast to the low condensation ratio of the high AP cells in the sorted fraction, the AP activity and osteocalcin contents were about nine times and four times greater than those of the unsorted cells, respectively. These results demonstrated that using the sorting technique to isolate the high AP cells might be a useful method for applications in bone tissue engineering.
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PMID:Enhancement of in vitro osteoblastic potential after selective sorting of osteoblasts with high alkaline phosphatase activity from human osteoblast-like cells. 1546 79

Purpose. The antimicrobial effect of a silver-coated tumor endoprosthesis has been proven in clinical and experimental trials. However, in the literature there are no reports concerning the effect of elementary silver on osteoblast behaviour. Therefore, the prosthetic stem was not silver-coated because of concerns regarding a possible inhibition of the osseointegration. The aim of the present study was to investigate the effect of 5-25 mg of elementary silver in comparison to Ti-6Al-4V on human osteosarcoma cell lines (HOS-58, SAOS). Methods. Cell viability was determined by measuring the MTT proliferation rate. Cell function was studied by measuring alkaline phosphatase (AP) activity and osteocalcine production. Results. In the HOS-58 cells, the AP activity was statistically significant (P < 0.05) higher at a supplement of 5-10 mg of silver than of Ti-6 Al-4V at the same doses. For both cell lines, a supplement above 10 mg of silver resulted in a reduced AP activity in comparision to the Ti-6 Al-4V group, but a statistically significant difference (P < 0.05) was observed at a dose of 25 mg for the SAOS cells only. At doses of 20-25 mg in the HOS-58 cells and 10-25 mg in the SAOS cells, the reduction of the proliferation rate by silver was statistically significant (P < 0.05) compared to the Ti-6 Al-4V supplement. Discussion. In conclusion, elementary silver exhibits no cytotoxicity at low concentrations. In contrast, it seems to be superior to Ti-6 Al-4V concerning the stimulation of osteogenic maturation at these concentrations, whereas at higher doses it causes the known cytotoxic properties.
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PMID:The influence of elementary silver versus titanium on osteoblasts behaviour in vitro using human osteosarcoma cell lines. 1768 31

The aim of this work was to study the in vitro biocompatibility of glass-ceramic scaffolds based on 45S5 Bioglass, using a human osteosarcoma cell line (HOS-TE85). The highly porous scaffolds were produced by the foam replication technique. Two different types of scaffolds with different porosities were analysed. They were coated with a biodegradable polymer, poly(3-hydroxybutyrate) (P(3HB)). The scaffold bioactivity was evaluated by soaking in a simulated body fluid (SBF) for different durations. Compression strength tests were performed before and after immersion in SBF. These experiments showed that the scaffolds are highly bioactive, as after a few days of immersion in SBF a hydroxyapatite-like layer was formed on the scaffold's surface. It was also observed that P(3HB)-coated samples exhibited higher values of compression strength than uncoated samples. Biocompatibility assessment was carried out by qualitative evaluation of cell morphology after different culture periods, using scanning electron microscopy, while cell proliferation was determined by using the AlamarBlue assay. Alkaline phosphatase (ALP) and osteocalcin (OC) assays were used as quantitative in vitro indicators of osteoblast function. Two different types of medium were used for ALP and OC tests: normal supplemented medium and osteogenic medium. HOS cells were seeded and cultured onto the scaffolds for up to 2 weeks. The AlamarBlue assay showed that cells were able to proliferate and grow on the scaffold surface. After 7 days in culture, the P(3HB)-coated samples had a higher number of cells on their surfaces than the uncoated samples. Regarding ALP- and OC-specific activity, no significant differences were found between samples with different pore sizes. All scaffolds containing osteogenic medium seemed to have a slightly higher level of ALP and OC concentration. These experiments confirmed that Bioglass/P(3HB) scaffolds have potential as osteoconductive tissue engineering substrates for maintenance and normal functioning of bone tissue.
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PMID:In vitro biocompatibility of 45S5 Bioglass-derived glass-ceramic scaffolds coated with poly(3-hydroxybutyrate). 1917 Feb 50


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