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At least 415 records · Page 23Linked to original sources
PubMed2000

Vascular endothelial growth pattern of endochondral bone graft in the presence of demineralized intramembranous bone matrix--quantitative analysis.

OBJECTIVE: To determine the timely ingrowth of new blood vessels of composite endochondral (EC) bone and demineralized bone matrix (DBM) prepared from intramembranous (IM) origin (EC-DBM(IM)) and to compare it with EC bone graft alone. DESIGN: Thirty-two rabbits with 32 critical-size (10 x 5 mm), full-thickness bony defects in rabbit parietal bone were divided into two groups: composite EC-DBM(IM) group-implanted with composite autogenous EC bone and DBM(IM); EC bone group-implanted with EC bone alone. Two rabbits from each group were sacrificed-1, 2, 3, 4, 5, 6, 7, and 14 days after grafting. Neovascularization was assessed by immunohistochemical staining with antihuman angiogenesis-related endothelial cell antibodies (EN 7/44). Quantitative analysis of neovascularization, represented by percentage area of positive immunohistochemical staining, was performed on 320 sections of the experimental groups by a computer-assisted image analyzer. RESULTS: Positive immunohistochemical staining was first identified on day 2 post grafting for the composite EC-DBM(IM) group in comparison with day 4 in the EC bone graft group. The composite EC-DBM(IM) bone graft group showed earlier and almost 100% more neovascularization when compared with the EC bone graft group. CONCLUSION: DBM(IM) enhances healing and integration of EC bone graft by enhancing vascularization as well as increasing the amount of new blood vessels formed. In clinical cases in which EC autogenous bone is used to graft a large defect such as in cleft palate and craniofacial surgery, DBM(IM) should allow better integration and healing of the EC bone graft to the host bone.

Animals↗
PubMed2002

Enhanced guided bone regeneration with a resorbable chamber containing demineralized bone matrix.

BACKGROUND: The effectiveness of a nonporous poly-DL-lactide tubular chamber in guiding bone regeneration through a long bone defect had already been assessed in an experimental model using the rabbit radius. The injection of bone marrow stem cells into the chamber had proven to enhance bone regeneration. METHODS: The present study reports on the development of the above research project in a subsequent stage. Demineralized bone matrix (DBM) obtained by milling New Zealand rabbit femoral and tibial diaphyses was placed into a tubular chamber. A 10-mm defect was bilaterally created in the radii of 10 rabbits. On the left side (chamber side) the defect was treated by means of a poly-DL-lactide chamber filled with DBM, whereas DBM alone was used on the right side (control). RESULTS: Controls were performed at 3 and 6 months by radiographs and histomorphometry and demonstrated better bone growth on the chamber side versus the control side. A comparison with the results previously obtained by stem cell injection into the chamber revealed significant acceleration of bone regrowth in the first 3 months because of the addition of DBM to the chamber. However, no significant difference was found between the two sides after 6 months. CONCLUSION: These results have confirmed the effectiveness of the chamber as a container for the factors promoting bone regeneration, probably because the osteogenetic activity is maintained in situ.

Absorbable Implants↗
PubMed1993

Ultrastructure of calcified muscle fibres at the implantation site of demineralized bone matrix gelatin.

To clarify the mechanism of calcification during new bone formation induced by demineralized bone matrix gelatin (BMG), BMG was implanted into the skeletal muscle of Sprague-Dawley (SD) rats and histological changes were examined 1,2,3,5,7 and 10 days later. From day 2 after implantation, calcification was observed in muscle fibres near the implanted BMG. Calcification of the BMG ('acellular mineral deposition') was first seen on day 3 and in both, calcification increased. The calcification of muscle fibre was first seen in the sarcoplasmic reticulum (SR) and then in mitochondria or lipid droplet-like structures of satellite cells. The muscle mineral deposition occurred without osteogenic cells and matrix vesicles in the same way as 'acellular mineral deposition'.

Animals↗
PubMedDate not supplied

[The dependence of the osteoinductive activity of the bone matrix on the mass and area of the transplant].

White rat experiments have demonstrated that bone matrix osteoinductive activity (the matrix ability to induce ectopic osteogenesis) is in direct proportion with the transplant mass in cases when this mass is within 0 to 0.16% b. m. A higher transplant mass is not associated with elevated osteoinductive activity. When the transplant masses are equal, their osteoinductive activities are in proportion with their sizes. These regularities should be borne in mind when choosing the transplant mass and shape.

Animals↗
PubMed1996

Cytokine-induced inhibition of bone matrix proteins is not mediated by prostaglandins.

Interleukin-1 (IL-1) and tumor necrosis factor (TNF), two pleiotropic cytokines produced in inflammatory processes, inhibit bone matrix biosynthesis and stimulate prostanoid formation in osteoblasts. In the present study, the importance of prostaglandin formation in IL-1 and TNF-induced inhibition of osteocalcin and type I collagen formation has been examined. In the human osteoblastic cell line MG-63, IL-1 alpha (10-1000 pg/ml), IL-1 beta (3-300 pg/ml) and TNF-alpha (1-30 ng/ml) stimulated prostaglandin E2 (PGE2) formation and inhibited 1,25(OH)2-vitamin D3-induced osteocalcin biosynthesis as well as basal production of type I collagen. Addition of PGE2 or increasing the endogenous formation of PGE2 by treating the cells with arachidonic acid, bradykinin, Lys-bradykinin or des-Arg9-bradykinin, did not affect osteocalcin and type I collagen formation in unstimulated or 1,25(OH)2-vitamin D3-stimulated osteoblasts. Four non-steroidal antiinflammatory drugs, indomethacin, flurbiprofen, naproxen and meclofenamic acid, inhibited basal, IL-1 beta- and TNF-alpha-stimulated PGE2 formation in the MG-63 cells without affecting IL-1 beta- or TNF-alpha-induced inhibition of osteocalcin and type I collagen formation. In isolated, non-transformed, human osteoblast-like cells, IL-1 beta and TNF-alpha stimulated PGE2 formation and concomitantly inhibited 1,25(OH)2-vitamin D3-stimulated osteocalcin biosynthesis, without affecting type I collagen formation. In these cells, indomethacin and flurbiprofen abolished the effects of IL-1 beta and TNF-alpha on prostaglandin formation without affecting the inhibitory effects of the cytokines on osteocalcin biosynthesis. These data show that IL-1 and TNF inhibit osteocalcin and type I collagen formation in osteoblasts independently of prostaglandin biosynthesis and that non-steroidal antiinflammatory drugs do not affect the effects of IL-1 and TNF on bone matrix biosynthesis.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Estimation of bone matrix apparent stiffness variation caused by osteocyte lacunar size and density.

The role of osteocyte lacunar size and density on the apparent stiffness of bone matrix was predicted using a mechanical model from the literature. Lacunar size and lacunar density for different bones from different gender and age groups were used to predict the range of matrix apparent stiffness values for human cortical and cancellous tissue. The results suggest that bone matrix apparent stiffness depends on tissue type (cortical versus cancellous), age, and gender, the magnitudes of the effects being significant but small in all cases. Males had a higher predicted matrix apparent stiffness than females for vertebral cancellous bone (p< I0(-7)) and the difference increased with age (p =0.0007). In contrast, matrix apparent stiffness was not different between males and females forfemoral cortical bone and increased with age in both males (p < 0.0001) and females (p < 0.0364). Osteocyte lacunar density and size may cause significant gender and age-related variations in bone matrix apparent stiffness. The magnitude of variations in matrix apparent stiffness was small within the physiological range of lacunar size and density for healthy bone, whereas the variations can be profound in certain pathological cases. It was proposed that the mechanical effects of osteocyte density be uncoupled from their biological effects by controlling lacunar size in normal bone.

Adolescent↗
PubMed1983

Age and sex variations of bone matrix proteins in Wistar rats.

Collagen and noncollagenous proteins (NCP) have been studied in Wistar rats according to the age and sex. The total amounts of bone matrix proteins, EDTA extracts and the soluble collagenase resistant fraction (SCRF) decreases with aging while the insoluble collagenase resistant fraction (ICRF) increases. No consistent sex-differences have been observed. In the bone matrix, the sialic acid and hexose contents increase with age, the uronic acid value decreases while hydroxyproline does not change. In the EDTA extracts, the collagen extractability decreases markedly with age, the sialic acid content increases while the hexose and uronic acid contents do not vary. Plasma proteins (albumin, orosomucoid and IgG) also do not change with aging. In the collagenase digests, no age and sex differences were found in the collagen and noncollagenous proteins of the SCRF while in the ICRF a decrease was observed for hexoses, uronic acid and sialic acid and an increase for hydroxyproline from the third month onwards.

Age Factors↗
PubMed1983

Osteoinduction within porous polysulfone implants at extraosseous sites using demineralized allogeneic bone matrix.

The objective of this study was to determine if bone induction could occur in implants of porous polysulfone (PPSF) impregnated with particles of demineralized allogeneic bone matrix (DABM). DABM-PPSF composites were fabricated by inserting DABM particles into PPSF specimens. The porous implants were produced by sintering polysulfone particles (850-1180 micron in diameter). DABM particles were prepared by demineralizing rat cortical bone in 0.6N HCl at 4 degrees C for 18-24 h. A composite DABM-PPSF specimen and three "controls" were implanted subcutaneously at abdominal sites in 30 adult Sprague-Dawley rats. The three controls were whole DABM (4 X 4 X 1 mm), particulate DABM (1 X 1 X 1 mm), and porous polysulfone (5 X 5 X 1 mm). Microradiographic and histological evaluation of DABM-PPSF composites revealed chondrogenesis within the pores of the specimens at 10 days, followed by ossification and fatty marrow production at 21 and 43 days. This histological sequence was similar to that seen with DABM controls. The tissue response to porous polysulfone did not prevent the osteoinductive process. These results suggest that an osteoinductive material such as DABM may be useful in augmenting the implantation of porous implants at osseous sites in which the potential for bone regeneration is limited.

Animals↗
PubMed1994

Bone matrix decorin binds transforming growth factor-beta and enhances its bioactivity.

In an effort to clarify the regulation of distribution and actions of transforming growth factor (TGF)-beta in bone, TGF-beta 1 binding to extracted bone matrix proteins and the influence of such binding on TGF-beta 1 actions were examined. In-gel binding of 125I-TGF-beta 1 using extracts from mineralized bovine bone matrix demonstrated that 125I-TGF-beta 1 was almost exclusively bound to a proteoglycan, decorin. The binding was via the core protein of decorin. Scatchard analysis of the binding of 125I-TGF-beta 1 to immobilized decorin purified from osteoblastic MC3T3-E1 cell conditioned medium revealed that there were two specific binding sites with high and low affinities for TGF-beta 1 (Kd = 0.3 and 5 nM, respectively). The addition of decorin along with TGF-beta 1 enhanced the inhibitory effect of TGF-beta 1 on MC3T3-E1 cell proliferation. Decorin in itself did not affect their proliferation. These cells possessed types I and II TGF-beta receptors and betaglycan, and the addition of decorin increased the binding of 125I-TGF-beta 1 to all these receptors. These results demonstrate that the core protein of decorin specifically binds TGF-beta 1 with high affinities and that the binding of TGF-beta 1 to decorin increases TGF-beta 1 binding to its receptors and enhances its bioactivity. Because TGF-beta is released by bone resorption along with matrix proteins, including decorin, and because it stimulates the synthesis of these proteins, it is suggested that the binding and enhancement of the activities of TGF-beta by decorin may play a role in maintaining bone formation during bone remodeling process.

3T3 Cells↗
PubMed1994

Early bone matrix formation during distraction. A biochemical study in sheep.

Osteotomy of the distal radius and gradual distraction were performed on 20 sheep. Bone matrix synthesized between the osteotomized bone ends was biochemically characterized at 3, 5, 7, and 14 days after the start of distraction. The deposition of mineral was negligible during the 14-day period. No change was observed in the amount of organic matrix, which comprised 15 +/- 1.4 percent of the wet weight of the tissue. The amount of total protein of the wet weight in the matrix increased from 4.6 to 7.6 percent between 5 and 7 days of distraction. During the first 7 days, the nonprotein component decreased from 11 to 7.3 percent. The proportion of collagen of the total matrix protein increased gradually from 29 to 59 percent. In view of the patterns of the cyanogen bromide peptides of the matrix proteins, the heteropolymer type I[1(I)2(2)(I)1] collagen was consisted to be the principle fibrillar collagen synthesized in the distraction gap. The results suggest that tension-stress markedly affects the synthesis of fibrillar collagen towards the formation of mature bone matrix. In this process, a preliminary lag phase probably exists during which the capacity for protein synthesis is low while the synthesis of Type I collagen has started. In the secondary phase an augmented synthesis of Type I collagen takes place.

Animals↗
PubMed2003

Osteogenesis by guided tissue regeneration and demineralized bone matrix.

AIM: To evaluate in a discriminating capsule model whether bone formation by guided tissue regeneration (GTR) may be influenced by concomitant implantation of demineralized bone matrix (DBM). MATERIALS AND METHODS: Thirty 4-month-old male albino rats of the Wistar strain were used in the study. Following surgical exposure of the mandibular ramus, a hemispherical, Teflon capsule (5.0 mm in diameter), loosely packed with a standardized amount of DBM, was placed with its open part facing the lateral bone surface of the ramus. At the contralateral side, an empty capsule was placed, serving as control. After healing periods of 15, 30, and 120 days, groups of 10 animals were sacrificed and 40-70 microm thick undecalcified sections of the capsules were produced. In the sections, the cross-sectional areas of (1) the space created by the capsule, (2) newly formed bone, (3) DBM particles, (4) loose connective tissue as well as the (5) height of the capsules, and (6) that of the newly formed bone were measured. RESULTS: Increasing bone fill was observed in both test and control sites from 30 to 120 days. After 30 days of healing, the mean amount of bone was approx. 3% of the cross-sectional area of the capsules at the test sites while it was 8% in the control sites (p<0.05). However, no statistically significant differences were observed between the test (46%) and control (64%) sites after 120 days regarding any of the measured parameters (p>0.05). The newly formed bone in the DBM group at 120 days, on the other hand, appeared more dense than that in the control capsules. CONCLUSION: DBM used as an adjunct to GTR did not provide any added effect on bone formation but increased the density of the newly formed bone.

Animals↗
PubMed1987

[Purification and properties of a growth factor from human bone matrix].

A growth factor was isolated from demineralized human bone-matrix and purified approximately 2,300-fold with 5.6% yield by the procedures of acetone treatment, Blue-A matrix gel chromatography, Sephadex G-75 gel filtration and Mono-Q fast protein liquid chromatography. The final preparation was homogeneous and a single polypeptide of 18,000 daltons as judged by SDS-polyacrylamide gel electrophoresis. The purified growth factor stimulated DNA synthesis in embryonic chick osteoblast in a dose-dependent manner and was saturated at the concentration of 4 ng/ml. By comparing various properties of the final preparation with those of other growth factors derived from bone, it appears to be a novel growth factor, and may be one of the important local regulators of bone remodeling.

Animals↗
PubMed1997

Sequential expression of bone matrix proteins during rat calvaria osteoblast differentiation and bone nodule formation in vitro.

We investigated the expression of osteocalcin (OC), bone sialoprotein (BSP), osteonectin (ON), and alkaline phosphatase (ALP) during cell differentiation and bone nodule formation by fetal rat calvaria cells, using immunofluorescent and immunogold techniques at light and electron microscopic levels. Six hours after plating all proteins were expressed in calvaria cells. However, expression was not detected during the proliferation phase after plating. Cell morphological modifications were observed in osteoblastic cells expressing ALP, OC, and BSP, but not ON. During the matrix formation phase, all proteins were expressed with various intensities and OC was limited to differentiated osteoblastic cells. EM observations demonstrated that BSP was selectively associated with clusters of needle-like crystals, but not with collagen fibers, in mineralization foci and in the mineralized matrix. OC was localized intracellularly and in all the extracellular compartments, and was concentrated at the mineralization front. ON was distributed uniformly throughout the osteoid and mineralized matrix, which was intensely labeled. The results show that the expression of bone matrix proteins during differentiation of calvaria cells and nodule formation in vitro duplicate what is observed during osteogenesis in vivo.

Alkaline Phosphatase↗
PubMed2007

Bone matrix formation in osteogenic cultures derived from human embryonic stem cells in vitro.

Bone matrix production and mineralization involves sophisticated mechanisms, including the initial formation of an organic extracellular matrix into which inorganic hydroxyapatite crystals are later deposited. Human embryonic stem (hES) cells offer a potential to study early developmental processes and provide an unlimited source of cells. In this study, four different hES cell lines were used, and two different approaches to differentiate hES cells into the osteogenic lineage were taken. Undifferentiated cells were cultured either in suspension, facilitating the formation of embryoid bodies (EBs), or in monolayer, and both methods were in the presence of osteogenic supplements. Novel to our osteogenic differentiation study was the use of commercially available human foreskin fibroblasts to support the undifferentiated growth of the hES cell colonies, and their propagation in serum replacement-containing medium. Characterization of the osteogenic phenotype revealed that all hES cell lines differentiated toward the mesenchymal lineage, because T-Brachyury, Flt-1, and bone morphogenetic protein-4 could be detected. Main osteoblastic marker genes Runx2, osterix, bone sialoprotein, and osteocalcin were up-regulated. Alizarin Red S staining demonstrated the formation of bone-like nodules, and bone sialoprotein and osteocalcin were localized to these foci by immunohistochemistry. Cells differentiated in monolayer conditions exhibited greater osteogenic potential compared to those from EB-derived cells. We conclude that in vitro hES cells can produce a mineralized matrix possessing all the major bone markers, the differentiation of pluripotent hES cells to an osteogenic lineage does not require initiation via EB formation, and that lineage potential is not dependent on the mode of differentiation induction but on a cell line itself.

Bone Matrix↗
PubMed1997

New aspects of endochondral ossification in the chick: chondrocyte apoptosis, bone formation by former chondrocytes, and acid phosphatase activity in the endochondral bone matrix.

A detailed histological study of the growth plates from 9- to 20-day-old embryonic chick long bones was carried out with the aim of clarifying the long-debated question of the fate of the hypertrophic chondrocytes. Since resorption in chick bones does not occur synchronously across the plate as it does in mammals, specialized regions develop and the fate of the chondrocyte depends on its location within the growth plate. Where resorption took place, as at the sites of primary vascular invasion or at the main cartilage/marrow interface, chondrocytes underwent apoptosis before the lacunae were opened. In addition, spontaneous apoptosis of chondrocytes occurred at apparently random sites throughout all stages of chondrocyte differentiation. In older chick bones, a thick layer of endochondral bone matrix covered the cartilage edge. This consisted of type I collagen and the typical noncollagenous bone proteins but, in addition, contained tartrate-resistant acid phosphatase in the mineralized matrix. Where such matrix temporarily protected the subjacent cartilage from resorption, chondrocytes differentiated to bone-forming cells and deposited bone matrix inside their lacunae. At sites of first endochondral bone formation, some chondrocytes underwent an asymmetric cell division resulting in one daughter cell which underwent apoptosis, while the other cell remained viable and re-entered the cell cycle. This provided further support for the notion that chondrocytes as well as marrow stromal cells give rise to endochondral osteoblasts.

Acid Phosphatase↗