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PubMed1992

Acidic phosphoproteins from bone matrix: a structural rationalization of their role in biomineralization.

Osteopontin, bone sialoprotein, and bone acidic glycoprotein-75 are three acidic phosphoproteins that are isolated from the mineralized phase of bone matrix, are synthesized by osteoblastic cells, and are generally restricted in their distribution to calcified tissues. Although each is a distinct gene product, these proteins share aspartic/glutamic acid contents of 30-36% and each contains multiple phosphoryl and sialyl groups. These properties, plus a strict relationship of acidic macromolecules with cell-controlled mineralization throughout nature, suggest functions in calcium binding and nucleation of calcium hydroxyapatite crystal formation. However, direct proof for such roles is still largely indirect in nature. The purpose of this review is to present two speculative hypotheses regarding acidic phosphoprotein function. The goal was to use new sequence information along with database comparisons to develop a structural rationalization of how these proteins may function in calcium handling by bone. For example, our analysis has identified a conserved polyacidic stretch in all three phosphoproteins which we propose mediates metal binding. Also, conserved motifs were identified that are analogous with those for casein kinase II phosphorylation sites and whose number correlates well with that of phosphoryl groups/protein. A two-state conformational model of calcium binding by bone matrix acidic phosphoproteins is described which incorporates these findings.

Amino Acid Sequence↗
PubMed1986

Osteogenesis promoted by bone matrix combined with marrow. Titanium implants studied in rats.

We evaluated the bone-forming potential of isogeneic bone marrow combined with antigen-extracted, autolyzed allogeneic bone matrix (AAA bone a.m. Urist). The purpose of the experiment was to evaluate bone-inducing materials for application in orthopaedic devices designed for fixation by bone ingrowth into a porous surface. The bone-forming materials were packed into tubes of porous fiber titanium and placed in the back musculature of rats for 12 or 25 days. At 12 days the combination of bone marrow and AAA bone had produced more bone than marrow only. At 25 days, however, there was no difference. The bone-inducing materials produced substantial amounts of new bone, and may become an adjuvant for achieving fixation by bone ingrowth. In particular, a combination of AAA bone and marrow might enhance fixation at a very early postoperative stage.

Animals↗
PubMed1997

[The use of human lyophilized bone matrix gelatin in oral surgery (preliminary report)].

Clinical application of human freeze-dried bone matrix gelatin (BMG) in the bone-cysts is reported. The BMG is produced at the West Hungarian Regional Tissue Bank in Gyór under principles of the American and European Association of Tissue Banks. BMG was applied to fill bone cysts in maxilla and mandible. The BMG has many advantages in comparison to other materials in the management of maxillofacial cysts. Of 31 cases 28 primary bone-heating have been detected clinically assessed by X-ray and histologically in three cases there was secondary restoration. In the favourable courses very fast and effective restorations have been found. The authors possess very favorable experience on the field of implantation of human bone matrix gelatin and recommend its clinical application at the maxillofacial surgery.

Bone Cysts↗
PubMed2005

The efficacy of different commercially available demineralized bone matrix substances in an athymic rat model.

OBJECTIVE: Bone graft substitutes have been developed because there is a limited supply of autogenous graft and the harvesting of iliac crest bone graft is associated with significant morbidity. Currently, there are a number of different commercially available demineralized bone matrix (DBM) products available that have been prepared by different methods and have different carriers. The objective of this study was to compare eight different commercially available DBM products. METHODS: Eight different DBMs were used to attempt a spinal fusion between the L4-L5 transverse processes in athymic rats. There were 10 rats in each group, and 5 rats were killed at both 4 and 8 weeks. Radiographic and histologic analyses were performed. Manual palpation testing was also performed. RESULTS: At 4 weeks, Osteofil Paste had the highest radiographic scores, whereas Grafton Putty had the best radiographic scores at 8 weeks. Conversely, the spines implanted with Allomatrix had the lowest radiographic scores at both 4 and 8 weeks. In regard to forming a spinal fusion confirmed by manual palpation, Osteofil Paste was the most effective at 4 weeks, whereas Grafton Flex and Grafton Putty had the highest rate of fusion at 8 weeks. Conversely, the lowest rates of fusion were seen in the Allomatrix and Grafton Crunch groups. Statistical analysis showed that there were significant differences among the groups seen on radiographs and by manual palpation. Qualitative differences could be appreciated between the groups histologically. CONCLUSION: Significant differences exist among commercially available DBMs in forming a spinal fusion in an athymic rat.

Animals↗
PubMed1985

Induction of endochondral bone by demineralized bone matrix from diabetic rats.

In this investigation we examined the osteoinductive potential of demineralized bone matrix derived from chronically diabetic (streptozotocin-induced) rats. Long-Evans rats (28-31 days) were made diabetic with a single injection of streptozotocin (65 mg/kg) and provided food and water ad lib for 2 months. Diaphyseal shafts of femurs and tibias removed from the diabetic rats and their sibling controls were dehydrated, pulverized, sieved to 74-420 micron particles, and demineralized. Matrix was then bioassayed for its ability to induce endochondral bone on day 11 following subcutaneous implantation over the thorax of Long-Evans rats. The resulting plaques of tissue were subjected to histological analysis, determination of alkaline phosphatase activity, and calcium content. Bone matrix derived from diabetic animals proved to be a significantly better inducer of endochondral bone than did control matrix.

Animals↗
PubMed2003

The ratio of osteocytic incorporation to bone matrix formation in femoral neck cancellous bone: an enhanced osteoblast work rate in the vicinity of hip osteoarthritis.

Recently it has been shown that an inactivating mutation in the TGFb-SMAD3 signaling pathway, which increases the conversion of osteoblasts to osteocytes, is accompanied by bone loss combined with increased osteocyte density. We hypothesized that increased matrix TGFb, known to occur in osteoarthritis, might cause the reverse of these effects in man. Because coxarthrosis (cOA) is associated with a reduced risk of femoral neck fracture, whole cross-section femoral neck biopsies were obtained from 11 patients with femoral neck fracture, 14 patients with cOA, and 22 age-and sex-matched controls. Lacunar density (Lc x mm2), osteocyte density (Ot x mm2), and cancellous wall width (Cn x W x Wi), were compared between cases of coxarthrosis, femoral neck fracture (FNF) and controls. In cOA, Lc.mm2 was reduced by 24% (P <0.001) while in FNF it was increased by 20% (P <0.001). Cn x W x Wi was increased in cOA by 22% (P <0.05) and in FNF was reduced by 27% (P <0.001). Lc x mm2 was inversely related to percentage cancellous bone area (adj. r2 = 0.373; P <0.01) and wall widths, r2 = 0.382, P <0.001. The reduction in osteocyte lacunar density coupled with increased wall width is consistent with a model of cOA effects on bone in which increased levels of matrix TGFb might prolong the effective lifespan or work rate of the osteoblast and delay its incorporation into the matrix as an osteocyte. One possible approach to strengthening bone in osteoporosis might be to enhance the effective lifespan of the osteoblast by modulating TGFb-related pathway activity in its local environment.

Aged↗
PubMed1994

Recombinant human bone morphogenetic protein-2 is superior to demineralized bone matrix in repairing craniotomy defects in rats.

The purpose of this study was to measure bone-regenerative effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) in rat calvarial critical-size defects (CSDs). CSDs (8 mm in diameter) were treated with either 1) 2.2 micrograms rhBMP-2 combined with insoluble collagenous bone matrix (ICBM), 2) 6.5 micrograms rhBMP-2 plus ICBM, 3) ICBM alone, or 4) demineralized bone matrix (DBM), for 7, 14, or 21 days. Multiple linear regression showed that rhBMP-2 had a significant time- and dose-dependent effect on bone regeneration (P < .05). After 7 days, new calcifying cartilage and remineralizing ICBM, with an occasional zone of new woven bone, was evident in defects treated with rhBMP-2/ICBM. By 14 days, both doses of rhBMP-2 reconstituted with ICBM had induced more bone formation than ICBM alone or DBM, and 6.5 micrograms was superior to 2.2 micrograms. There was no evidence of adverse cellular response. This study shows for the first time that rhBMP-2 could restore osseous form to a calvarial defect. In addition, osteoregeneration was accelerated by the higher dose of rhBMP-2.

Animals↗
PubMed1991

Osteoinductive property of fluoride impregnated decalcified allogeneic bone matrix.

Present study was carried out in order to explore the ability of a bone graft-decalcified as well as fluoridated to form new bone when put in the rectus abdominis muscle of rabbit. A total of 66 implants placed inside the pouches created in rectus abdominis muscle of rabbits were followed for 2 to 20 weeks. Radiologically decal implants formed bone in 74% cases and fluoridated implants in 68%; whereas histologically 86% of decalcified and 80% of fluoride impregnated decal bone matrix showed evidence of bone induction. It is concluded that fluoride impregnation does not enhance the osteogenic potential of a decal bone matrix.

Abdomen↗
PubMed1982

Autoradiographic study of the effect of 1,25-dihydroxyvitamin D3 on bone matrix synthesis in vitamin D replete rats.

An autoradiographic technique using pulse labels of [3H]proline was developed to assess the early effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on bone matrix synthesis in vitamin D replete rats. Rats, 7 days old, were given 0.25 2.5, or 25 ng of 1,25(OH)2D3 for vehicle alone subcutaneously on days 1, 3, and 5 of the experiment. Rats received a subcutaneous injection of 100 microCi [3H]proline on days 2 and 6 and were killed on day 7. Calvaria and tibia were processed for autoradiography, and morphometric methods were developed to measure the rate and amount of bone matrix formed during the experimental period. When compared to control values, the amount and rate of formation of new bone matrix were both signifIcantly decreased in rats receiving 25 ng of 1,25(OH)2D3 and slightly, but not significantly, decreased in rats receiving 2.5 ng. We conclude that administration of pharmacologic doses of 1,25(OH)2D3 to vitamin D replete rat pups impairs the formation of collagenous bone matrix.

Animals↗
PubMed2000

Optimizing human demineralized bone matrix for clinical application.

The use of human demineralized bone matrix (DBM) powder in periodontal and orthopedic applications is limited by the variability in the osteoinductive or osteoconductive properties of the material. The goal of the present study was to establish simple in vitro and in vivo assays of DBM that would allow us to screen different lots of the material prior to testing in more rigorous animal models. The results demonstrate a wide variability in the performance of individual lots of DBM powder obtained from a single tissue bank. The studies also demonstrate that relatively simple screening can be used to establish the quality of the different lots, and that performance and ease of handling can be improved by using relatively small particle sizes delivered in a fibrin sealant matrix.

Animals↗
PubMed1992

Incorporation of type I collagen molecules that contain a mutant alpha 2(I) chain (Gly580-->Asp) into bone matrix in a lethal case of osteogenesis imperfecta.

To understand more directly the tissue defect in osteogenesis imperfecta (OI), bone matrix was analyzed from an infant with lethal OI (type II) of defined mutation (collagen alpha 2(I)Gly580-->Asp). Pepsin-solubilized alpha 1(I) and alpha 2(I) chains and derived CNBr-peptides migrated more slowly on sodium dodecyl sulfate-polyacrylamide gel electrophoresis compared with normal human controls. The peptide alpha 2(I)CB3,5, predicted to contain the mutation site, ran as a retarded doublet band and was purified by high performance liquid chromatography and digested with V8 protease. Two peptides with amino-terminal sequences beginning at residue 576 of the alpha 2(I) chain were isolated. One had the normal sequence. The other differed in that aspartic acid replaced glycine at residue 580 as predicted from cDNA analysis, and in having an unhydroxylated proline at residue 579. From yields on microsequencing and the relative intensities of the two forms of alpha 2(I)CB3,5 on SDS-polyacrylamide gel electrophoresis, the ratio of mutant to normal alpha 2(I) chains in the infant's bone matrix was 0.7/1. Although the effects of an efficient incorporation of mutant chains on the properties of the bone matrix are unknown, it may be that in this OI case the tissue abnormalities result more from the presence of mutant protein than from an underexpression of matrix.

Amino Acid Sequence↗
PubMed1985

Contrasting effects of 1,25-dihydroxyvitamin D3 on bone matrix and mineral appositional rates in the mouse.

In order to determine the effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on bone matrix appositional rate (Ma AR) and bone mineral appositional rate (Mi AR), three doses (0.06, 0.13 and 0.20 microgram/kg/d) of 1,25(OH)2D3 were continuously infused for seven days in young mice. Histologic parameters of bone formation and resorption were evaluated by morphometric and autoradiographic methods. All doses of 1,25(OH)2D3 increased serum calcium and produced a dose-related increase in the metaphyseal osteoclastic surface and in the number of acid phosphatase-stained osteoclasts. The Mi AR evaluated by double tetracycline labeling was enhanced at all dosage levels. By contrast the Ma AR evaluated by double 3H-proline labeling was decreased at the two highest doses of 1,25(OH)2D3 which also produced growth impairment. We concluded that the continuous administration of 1,25(OH)2D3 in the mouse produces contrasting effects on bone matrix synthesis and calcification, resulting in a dose-related reduction in the amount of osteoid.

Animals↗
PubMed1989

[Treatment of post-osteomyelitic circular defects in shin bones by the method of compression-distraction osteosynthesis with the use of allogenic bone matrix].

The authors propose to stimulate distraction osteogenesis by means of implanting bone matrix both into the resection area after removing the suppurative necrotic focus and into the region of the osteotomized fragment. The suggested method of treatment of post-osteomyelitic defects of the tibia reduces the duration of the period of treatment 2-3-fold as compared with the commonly accepted terms in compression and distraction osteosynthesis without bone matrix.

Bone Matrix↗
PubMed1979

Degradation of bone matrix morphogenetic activity by pulverization.

The yield of new bone from implants of pulverized demineralized whole matrix and bone matrix gelatin declines as the particle size decreases in diameter below 125 microns. The corresponding increase in surface area and mechanically-induced free radicals is associated with an increase in solubility of bone matrix proteins. These changes in physiocochemical properties and the concomitant reduction in bone yield suggest that prolonged pulverization denatures a bone morphogenetic protein (BMP).

Animals↗
PubMed1977

The effect of bone matrix on young connective tissue cells in culture.

Human and rat decalcified bone matrix preparations were shown to be active in inducing cartilage formation by subcutaneous implantation in the rat. When young rat fibroblastic cells were grown in cultures, which also contained bone matrix preprations in particulate form, the fibroblastic cells underwent a uniform and consistent morphological alteration. These altered cells showed higher rates of synthesis of hyaluronic acid and chondroitin sulfate than the controls and exhibited very active amino-sugar-nucleotide metabolism. It is suggested that this approach to the culture of connective tissue cells will allow a more precise definition of the early steps of connective tissue differentiation.

Animals↗
PubMed1988

Inhibition of the inductive activity of demineralized bone matrix by different percutaneous implants.

Teflon tubes with either Gore-Tex (PTFE) or Dacron felt sleeves were implanted percutaneously in rats, in conjunction with demineralized bone matrix. This resulted in different inflammatory reactions, as well as in chondrogenesis and osteogenesis in the subcutaneous tissues. Although induction of osteogenesis by the demineralized bone matrix in the vicinity of the foreign material was inhibited, circumferential bone formation was highly reproducible. The prospect of utilizing demineralized bone matrix in order to enhance acceptance of percutaneous tubes is discussed.

Animals↗