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At least 595 records · Page 33Linked to original sources
PubMed1995

Human osteoblast-like cells respond to mechanical strain with increased bone matrix protein production independent of hormonal regulation.

Exposure of osteosarcoma cell lines to chronic intermittent strain increases the activity of mechano-sensitive cation (SA-cat) channels. The impact of mechano-transduction on osteoblast function has not been well studied. We analyzed the expression and production of bone matrix proteins in human osteoblast-like osteosarcoma cells, OHS-4, in response to chronic intermittent mechanical strain. The OHS-4 cells exhibit type I collagen production, 1,25-Dihydroxyvitamin D-inducible osteocalcin, and mineralization of the extracellular matrix. The matrix protein message level was determined from total RNA isolated from cells exposed to 1-4 days of chronic intermittent strain. Northern analysis for type I collagen indicated that strain increased collagen message after 48 h. Immunofluorescent labeling of type I collagen demonstrated that secretion was also enhanced with mechanical strain. Osteopontin message levels were increased several-fold by the application of mechanical load in the absence of vitamin D, and the two stimuli together produced an additive effect. Osteocalcin secretion was also increased with cyclic strain. Osteocalcin levels were not detectable in vitamin D-untreated control cells. However, after 4 days of induced load, significant levels of osteocalcin were observed in the medium. With vitamin D present, osteocalcin levels were 4 times higher in the medium of strained cells compared to nonstrained controls. We conclude that mechanical strain of osteoblast-like cells is sufficient to increase the transcription and secretion of matrix proteins via mechano-transduction without hormonal induction.

Blotting, Northern↗
PubMed1998

Impaired expression of noncollagenous bone matrix protein mRNAs during fracture healing in ascorbic acid-deficient rats.

In scorbutic patients, fractures are slow to heal because of impaired collagen synthesis. To investigate the influence of impaired collagen synthesis on the differentiation and proliferation of osteogenic and chondrogenic cells, we examined the expression of genes encoding bone matrix proteins, including osteonectin (ON), osteopontin (OPN), osteocalcin (OC), and matrix Gla protein (MGP), as differentiation markers for osteogenic and chondrogenic cells during fracture healing in Osteogenic Disorder Shionogi (ODS) rats, which have a hereditary defect in the ability to synthesize ascorbic acid (Asc). In ODS rats without Asc supplementation, intramembranous ossification was completely inhibited. Although a few fibroblast-like cells expressing ON mRNA were observed, no OPN mRNA-expressing cells were detected. During endochondral ossification, a small amount of metachromatic staining cartilage appeared at the fracture site, but there was no provisional calcification zone in the cartilage. Chondrocytes expressed ON and MGP mRNAs, but not OPN mRNA. When Asc was given to these rats, callus formation was soon detected around the fracture site, while OPN mRNA was expressed by differentiated osteoblasts and hypertrophic chondrocytes. Our data indicate that impaired collagen synthesis due to Asc deficiency inhibited the increase of ON and MGP mRNA-expressing cells as well as the appearance of OPN mRNA-expressing cells. Since OPN is considered to play an important role in normal and pathological mineralization, lack of OPN mRNA expression accompanying impaired collagen synthesis may have a role in defective mineralization and delayed fracture healing in scurvy.

Animals↗
PubMed2005

Effect of high hydrostatic pressure on biological properties of extracellular bone matrix proteins.

In orthopedic surgery, sterilization of bone used for reconstruction of osteoarticular defects caused by malignant tumors is carried out in various ways. At present, to devitalize tumor-bearing osteochondral segments, extracorporal irradiation or autoclaving is mainly used but both methods have substantial disadvantages, for instance, loss of biomechanical and biological integrity of the bone. In particular, after reimplantation, integration of the implant at the autograft-host junction is often impaired due to alteration of osteoinductivity as a result of its irradiation or autoclaving. As an alternative approach, high hydrostatic pressure (HHP) treatment of bone is suggested, a new technology which is in the preclinical testing stage, with the aim to inactivate tumor cells but leaving the biomechanical properties of bone, cartilage, and tendons intact. We investigated the influence of HHP on the major extracellular matrix (ECM) proteins, fibronectin (FN), vitronectin (VN), and type I collagen (Col-I), present in bone tissue, which are accountable for the biological properties within the bone. FN, VN, and Col-I were subjected to HHP < or = 600 MPa prior to coating of cell culture plates with these matrix proteins. Thereafter, the capacity of HHP-pretreated FN, VN, and Col-I to affect cell proliferation, cell adherence, and spreading of human primary osteoblast-like cells and the human osteosarcoma cell line Saos-2, was tested. Interestingly, even at HHP < or = 600 MPa, all three ECM proteins retained their biological properties because no significant changes were observed between HHP-treated and non-treated FN, VN, and Col-I regarding their biological properties to affect cell adherence, spreading, and proliferation. These data encourage further exploration of the potential of HHP to sterilize tumor-affected bone segments prior to reimplantation. While during this treatment eukaryotic cells including tumor cells will be irreversibly impaired, the bone's biomechanical properties and the biological properties of the ECM proteins FN, VN, and Col-I, respectively, are preserved.

Bone Matrix↗
PubMed2001

Tissue responses around polymethylmethacrylate particles implanted into bone: analysis of expression of bone matrix protein mRNAs by in situ hybridization.

Tissue responses around implanted polymethylmethacrylate (PMMA) particles were analyzed by in situ hybridization with digoxigenin-labeled procollagen alpha1(I) (COL), osteonectin, osteocalcin, and osteopontin (OPN) mRNA probes. PMMA particles (150-300 microm in diameter) were implanted into rat tibiae, and specimens were collected at 3, 5, 7, and 10 days after operation. New bone was formed centripetally, and bone-forming osteoblasts expressed all four kinds of mRNAs. A COL signal was expressed most strongly and widely. In the early stage, COL-positive cells were detected on and among particles sporadically. A COL signal was rarely detected in cells on the surfaces of the particles, suggesting that PMMA particles may suppress osteoblast differentiation. Osteonectin and osteocalcin mRNAs were expressed in bone-forming osteoblasts in a similar pattern by day 7. By contrast, an OPN signal was detected mainly on the particles, not only in COL-positive osteoblasts but also in COL-negative round cells. The latter cells had acid phosphatase activity, suggesting that they might be macrophages responding to a foreign body. At day 10, an OPN signal was detected continuously in multinucleated cells on PMMA particles, whereas new bone was formed away from particles. Our approach helped us to understand the initial cellular reaction to materials, which may determine their biocompatibility.

Animals↗
PubMed2001

Cadaveric fibula, locking plate, and allogeneic bone matrix for anterior cervical fusions after cervical discectomy for radiculopathy or myelopathy.

OBJECT: The authors have previously reported that the results of using cadaveric fibula and locking plate (CF/LP) fusion following anterior cervical discectomy (ACD) for cervical spondylotic radiculopathy and myelopathy are superior to those obtained using autologous iliac crest (AIC) grafts in the short term. The long-term results of using this construct are important in substantiating this improvement. The authors report on 246 consecutive patients (54% smokers) who underwent ACD with CF/LP fusion (175 with allogeneic bone matrix [ABM]) and compare them with 111 consecutive patients in whom AIC fusions (49% smokers) were performed by the same surgeons. METHODS: The study is a retrospective nonrandomized analysis, and chi-square statistics were used. Bone densitometric studies of AIC grafts and CF grafts were performed. A paired t-test was used for statistical analysis of the results. Disease in the group of patients undergoing CF/LP fusion included soft-disc herniation with radiculopathy in 14, soft-disc hemiation with myelopathy in seven, cervical spondylotic radiculopathy in 144, cervical spondylotic myelopathy in 75, AIC graft collapse pseudarthrosis in five, and ACD with no fusion collapse/kyphosis in one. Operations consisted of single-level CF/LP fusion in 142 patients and multilevel CF/LP fusion in 104. Perioperative complications in the CF/LP group included three cases of transient hoarseness. There were no transfusions, infections, neurological injuries, or deaths. The mean hospital length of stay was 1.2 days (28% outpatient and 66% 23-hour stay). The mean follow-up period was 60 months (range 12-94 months). Ten patients were lost to follow up after 1 year. Long-term complications included one traumatic plate fracture and one symptomatic pseudarthrosis with plate fracture. At 1 year and beyond, in 245 (99.6%) of 246 patients radiographically documented fusion with no motion at the fused level on flexion-extension films was demonstrated. There was no kyphosis, no symptomatic screw plate backout, and no CF/LP graft collapse (100% in the ABM group). In the 111 consecutive patients with AIC fusions, however, there was a 17% graft-related complication rate. There were significantly fewer graft-related complications in the CF/LP group (p < 0.001). There was no difference in neurological outcome for any of the groups. In the groups undergoing single-level ACD there was a significantly greater chance of complete relief of neck pain CF/LP fusion compared with those undergoing AIC fusion (p < 0.02). There was a significantly greater chance of AIC collapse with the passage of time compared with CF graft (p < 0.02). Time until return to work was shorter for the CF/LP group by 5 to 6 weeks (p < 0.02). There was a higher rate of radiographically documented pseudarthrosis in the AIC group (p < 0.006). The mean bone densitometry for the CF/LP group was 0.7 g/cm2, significantly greater than that of the AIC group, which was 0.2 g/cm2 (paired t-test p < 0.001). CONCLUSIONS: When fusion is necessary following ACD, the results of CF/LP fusion are significantly superior in the first 5 years after surgery compared with those for AIC fusions. It remains to be determined if demineralized ABM has a significant effect in enhancing fusion.

Adult↗
PubMed1998

Bone matrix proteins: isolation and characterization of a novel cell-binding keratan sulfate proteoglycan (osteoadherin) from bovine bone.

A small cell-binding proteoglycan for which we propose the name osteoadherin was extracted from bovine bone with guanidine hydrochloride-containing EDTA. It was purified to homogeneity using a combination of ion-exchange chromatography, hydroxyapatite chromatography, and gel filtration. The Mof the proteoglycan was 85, 000 as determined by SDS-PAGE. The protein is rich in aspartic acid, glutamic acid, and leucine. Two internal octapeptides from the proteoglycan contained the sequences Glu-Ile-Asn-Leu-Ser-His-Asn-Lys and Arg-Asp-Leu-Tyr-Phe-Asn-Lys-Ile. These sequences are not previously described, and support the notion that osteoadherin belongs to the family of leucine-rich repeat proteins. A monospecific antiserum was raised in rabbits. An enzyme-linked immunosorbent assay was developed, and showed the osteoadherin content of bone extracts to be 0.4 mg/g of tissue wet weight, whereas none was found in extracts of various other bovine tissues. Metabolic labeling of primary bovine osteoblasts followed by immunoprecipitation showed the cells to synthesize and secrete the proteoglycan. Digesting the immunoprecipitated osteoadherin with N-glycosidase reduced its apparent size to 47 kD, thus showing the presence of several N-linked oligosaccharides. Digestion with keratanase indicated some of the oligosaccharides to be extended to keratan sulfate chains. In immunohistochemical studies of the bovine fetal rib growth plate, osteoadherin was exclusively identified in the primary bone spongiosa. Osteoadherin binds to hydroxyapatite. A potential function of this proteoglycan is to bind cells, since we showed it to be as efficient as fibronectin in promoting osteoblast attachment in vitro. The binding appears to be mediated by the integrin alphavbeta3, since this was the only integrin isolated by osteoadherin affinity chromatography of surface-iodinated osteoblast extracts.

Amino Acid Sequence↗
PubMed1980

Effects of demineralization in an ethanolic solution of triethylammonium EDTA on solubility of bone matrix components and on ultrastructural preservation.

A solution of triethylammonium EDTA in 80% ethanol was evaluated as a demineralizing reagent for bone in comparison with aqueous solutions of EDTA. Biochemical analysis and acrylamide gel electrophoresis of extracts of finely powdered bovine bone showed that most of the macromolecular components of the organic matrix extractable in aqueous EDTA were retained when the triethylammonium EDTA reagent was used. Ultrastructural examination of chick tibias decalcified with the reagents showed a better preservation of cellular morphology, especially the membranous components, and more uniformly distributed ground substance, though slightly less in quantity, when the aqueous reagent was used. Use of the two reagents appears to be complementary, the alkylammonium reagent being more appropriate for use in studies of the organic matrix of bone, including immunohistochemical studies of bone glycoproteins. The aqueous reagent is more appropriate for use in studies of cellular ultrastructure.

Amino Acids↗
PubMedDate not supplied

Low-power laser irradiation improves histomorphometrical parameters and bone matrix organization during tibia wound healing in rats.

The influence of daily energy doses of 0.03, 0.3 and 0.9 J of He-Ne laser irradiation on the repair of surgically produced tibia damage was investigated in Wistar rats. Laser treatment was initiated 24 h after the trauma and continued daily for 7 or 14 days in two groups of nine rats (n=3 per laser dose and period). Two control groups (n=9 each) with injured tibiae were used. The course of healing was monitored using morphometrical analysis of the trabecular area. The organization of collagen fibers in the bone matrix and the histology of the tissue were evaluated using Picrosirius-polarization method and Masson's trichrome. After 7 days, there was a significant increase in the area of neoformed trabeculae in tibiae irradiated with 0.3 and 0.9 J compared to the controls. At a daily dose of 0.9 J (15 min of irradiation per day) the 7-day group showed a significant increase in trabecular bone growth compared to the 14-day group. However, the laser irradiation at the daily dose of 0.3 J produced no significant decrease in the trabecular area of the 14-day group compared to the 7-day group, but there was significant increase in the trabecular area of the 15-day controls compared to the 8-day controls. Irradiation increased the number of hypertrophic osteoclasts compared to non-irradiated injured tibiae (controls) on days 8 and 15. The Picrosirius-polarization method revealed bands of parallel collagen fibers (parallel-fibered bone) at the repair site of 14-day-irradiated tibiae, regardless of the dose. This organization improved when compared to 7-day-irradiated tibiae and control tibiae. These results show that low-level laser therapy stimulated the growth of the trabecular area and the concomitant invasion of osteoclasts during the first week, and hastened the organization of matrix collagen (parallel alignment of the fibers) in a second phase not seen in control, non-irradiated tibiae at the same period. The active osteoclasts that invaded the regenerating site were probably responsible for the decrease in trabecular area by the fourteenth day of irradiation.

Animals↗
PubMed1995

Alterations of bone matrix protein mRNA expression in rat aorta in vitro.

We examined the expression of matrix Gla protein (MGP), osteopontin (OPN), and osteonectin (ON) mRNAs in aortic rings excised from 3-month-, 10-month-, and 2-week-old rats during 72-hour incubations in serum-free media. In the aortic rings from 3-month-old rats, the expression of MGP mRNA was strong before incubation and increased during the 72-hour incubation. The expression of OPN mRNA was first detected after a 5-hour incubation and increased thereafter, and that of ON mRNA was strong before the incubation and decreased during the incubation. The expression of MGP and OPN mRNAs in 10-month- and 2-week-old rats was similar to that in 3-month-old rats. In contrast, expression of ON mRNA in 10-month-old rats and the expression of ON mRNA in 2-week-old rats was stronger than that in 3-month-old rats at every incubation period. In situ hybridization and immunohistochemistry identified the MGP, OPN, and ON mRNA-expressing cells as vascular smooth muscle cells. These results suggest that the expression of these mRNAs was regulated in incubation time-dependent and age-specific ways. We believe that this organ culture model is useful for further studies of the function of these bone matrix proteins and regulation of their expression in the vessel wall.

Animals↗
PubMed2002

Gene expression of bone matrix proteins in a calcified tissue appeared in subcutaneously transplanted rat dental pulp.

Dental pulp self-mineralizes or induces calcified tissue formation, when it is subcutaneously transplanted. This study aims to clarify the nature and process of this tissue calcification by using histochemical techniques and in situ hybridization methods. The dental pulps of incisors from Sprague-Dawley strain rats were homogeneously transplanted into the subcutaneous tissue of the head of another rat. On the 1st day of transplantation, the mRNAs of type I collagen (COL I) and bone sialoprotein (BSP) were expressed in the transplant. On the 5th to 7th days after transplantation, von Kossa-positive, calcified tissues appeared in the transplanted tissues. The mRNAs of COL I, BSP and osteopontin (OPN) were expressed with the same distributions as those of the von Kossa-positive areas, but those of type II collagen (COL II) and bone morphogenic protein 2 (BMP-2) were not expressed in the transplant. When the cellular incorporation of BrdU was examined after its subcutaneous injection into the animals, positive cells were present in the von Kossa-positive calcified foci as well as in their surrounding areas. These results indicate that the transplanted dental pulp possesses the ability to induce cell proliferation resulting in the synthesis of several bone matrix proteins and the formation of calcified tissue. This may give us an insight into the nature and processes of pulp obliteration, which occurs in a human tooth following an episode of trauma.

Animals↗
PubMed2003

Comparison of human bone marrow stromal cells seeded on calcium-deficient hydroxyapatite, beta-tricalcium phosphate and demineralized bone matrix.

The aim of this study was to compare three resorbable biomaterials regarding seeding efficacy with human bone marrow stromal cells (BMSCs), cell penetration into the matrix, cell proliferation and osteogenic differentiation. Calcium-deficient hydroxyapatite (CDHA), beta-tricalcium phosphate (beta-TCP), and demineralized bone matrix (DBM) were seeded with human BMSCs and kept in human serum and osteogenic supplements for 3 weeks. Morphologic and biochemical evaluations were performed on day 1, 7, 14 and 21. The allograft DBM and CDHA exhibited both an excellent seeding efficacy while the performance of beta-TCP was lower when compared. The total protein content and the values for specific alkaline phosphatase (ALP) increased on all matrices and no significant difference was found for these two markers. BMSCs in monolayer had a significant increase of protein, but not of ALP. Osteocalcin (OC) values increased significantly higher for BMSC in cultures on DBM when compared to CDHA and beta-TCP. The OC levels decreased significantly in the BMSC monolayer culture. BMSCs were found inconsistently within the synthetic materials, whereas in DBM they were found more homogeneously distributed throughout the matrix. All three matrices promoted BMSC proliferation and differentiation to osteogenic cells. DBM allografts seem to be more favorable with respect to cell ingrowth tested by histology, and osteogenic differentiation ascertained by an increase of OC. CDHA with its high specific surface area showed more favorable properties than beta-TCP regarding reproducibility of the seeding efficacy.

Biocompatible Materials↗
PubMed2003

GBR using bovine bone matrix and resorbable and nonresorbable membranes. Part 1: histologic results.

Ninety sites were treated with either sinus augmentation therapy using only Bio-Oss (31 sites), or extraction socket and ridge augmentation therapy using only Bio-Oss beneath secured resorbable or titanium-reinforced nonresorbable membranes (59 sites). Core biopsies were taken at intervals ranging from 4 to 13 months. The 12 core biopsies taken 12 to 13 months postoperative (five sinus augmentation sites and seven extraction socket/ridge augmentation sites) demonstrated distinct Bio-Oss particles in an average of only 0.13% of the core biopsy volume. Bone regeneration was evident in all specimens.

Absorbable Implants↗
PubMed1986

Regional variation of bone matrix components in osteoarthrotic and normal femoral heads.

Three regios of cancellous bone, two subchondral and one central, from the femoral heads of five normal and ten osteoarthrotic individuals were analysed for their content of collagen, sialoprotein, proteoglycan and carbohydrate. Confirming previous findings in osteoarthrotic bone this study shows that there are significant quantitative changes in matrix composition consisting of a decrease in collagen content and increase in noncollagenous proteins in osteoarthrosis. Since these matrix alterations were present in all areas of the femoral head, also at areas distal from the subchondral area, it is unlikely that these changes are secondary to bone remodeling near the joint destruction. Difference in matrix composition according to the area of the femoral head was also found in the controls, indicating that bone matrix proteins are related to mechanic properties of the bone. The more stress the bone has to withstand, the lower the collagen/noncollagenous protein ratio in its matrix. These observations suggest that in osteoarthrosis, the bone is stiffer and can therefore absorb less well impact loading and by transmitting it back to the cartilage provokes cartilage dysfunction.

Aged↗
PubMed2006

The mechanisms of uremic serum-induced expression of bone matrix proteins in bovine vascular smooth muscle cells.

We have previously found that uremic human serum upregulates RUNX2 in vascular smooth muscle cells (VSMCs), and that RUNX2 is upregulated in areas of vascular calcification in vivo. To confirm the role of RUNX2, we transiently transfected a dominant-negative RUNX2 (DeltaRUNX2) construct in bovine vascular smooth muscle cells (BVSMCs). Blocking RUNX2 transcriptional activity significantly decreased uremic serum induced alkaline phosphatase (ALP) activity (268+/-34 vs 188+/-9.5 U/g protein, P<0.05) and osteocalcin expression (172+/-17 vs 125+/-9 ODU, P<0.05). To determine the mechanism by which uremic serum upregulates RUNX2, we examined cell signaling pathways. BVSMCs were incubated in the presence or absence of inhibitors and RUNX2 expression and ALP activity were determined. The results demonstrate that the cyclic AMP (cAMP)/protein kinase A (PKA), but not protein kinase C, signaling pathway is involved in uremic serum-induced RUNX2 expression and ALP activity in BVSMCs. To examine potential uremic 'toxins', we measured bone morphogenetic protein (BMP)-2 concentration and found that uremic serum contained increased BMP-2 (uremic serum=169+/-33 pg/ml, normal serum=117+/-15 pg/ml, P<0.05). The incubation of BVSMCs with noggin, an inhibitor of BMP, decreased RUNX2 expression. In addition, BMP-2 secretion progressively increased during calcification and uremic serum enhanced its secretion compared to normal serum. In conclusion, this study demonstrates that RUNX2 transcriptional activity is critical in uremic serum-induced bone matrix protein expression in BVSMCs and that the cAMP/PKA pathway is involved. BMP-2 is also increased in uremic serum and can upregulate RUNX2 and calcification in vitro in VSMCs.

Alkaline Phosphatase↗
PubMed2003

GBR using bovine bone matrix and resorbable and nonresorbable membranes. Part 2: Clinical results.

Ninety sites were treated by sinus augmentation therapy using only Bio-Oss (31 sites) or extraction socket and ridge augmentation therapy using only Bio-Oss beneath secured resorbable or titanium-reinforced nonresorbable membranes (59 sites). The results of core biopsies taken at different intervals were discussed in part 1 of this study. A discussion of the use of resorbable versus reinforced nonresorbable membranes as a function of defect morphology is undertaken in part 2. Secured titanium-reinforced membranes were shown to be the most ideal means by which to ensure the final morphology of the regenerated hard tissues.

Absorbable Implants↗