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At least 433 records · Page 24Linked to original sources
PubMed2000

Immunosuppression with FK506 increases bone induction in demineralized isogeneic and xenogeneic bone matrix in the rat.

The aim of the present study was to investigate a systemic induction of bone formation in rats by immunosuppression with FK506 (1 mg/kg body weight intraperitoneally [ip]) in a model of osteoinduction of isogeneic and xenogeneic demineralized bone matrix (DBM) for a period of 28 days. In particular, alterations of in vitro cytokine synthesis and changes of lymphocyte subsets were studied. DBM was implanted intramuscularly in the abdominal wall of Lewis rats (seven per group). Blood was sampled on days -7, 0, 7, and 28 for determination of in vitro tumor necrosis factor a (TNF-alpha) synthesis and lymphocyte subsets by flow cytometry (CD3+, CD4+, CD8+, CD45+, ED9+, and Ia+ antibodies). Ossicles of de novo formed bone and the tibias were removed on day 28 after double tetracycline labeling for histomorphometric analysis. Immunosuppression with FK506 significantly decreased lipopolysaccharide (LPS)-stimulated in vitro cytokine synthesis after 7 days and 28 days (p < 0.05). Compared with control animals FK506 treatment significantly increased the volume of induced bone in isogeneic (2.1 +/- 0.3 mm3 vs. 10.8 +/- 0.9 mm3) and xenogeneic (O mm3 vs. 4.7 +/- 0.8 mm3) DBM. Bone histomorphometry of the tibias revealed that immunosuppression increased both bone formation and bone resorption, accompanied by a significant reduction in the relative trabecular area (Tb.Ar). FK506 caused a decrease in the counts of CD8+ T cells probably because of destruction or dislocation of these cells. This suggests that the amount of CD8+ cells and the degree of T cell activation in terms of mean fluorescence intensity (MFI) may be associated with bone metabolism. In support of this, statistical analysis revealed a significant positive correlation between parameters of bone formation as well as bone resorption and the CD4+/CD8+ ratio. There was a significant negative correlation between parameters of remodeling of the metaphysis of the tibia and induced bone volume (BV), respectively, and MFI values of CD3+/Ia+ cells. These findings suggest an important role of T lymphocytes in bone formation and bone resorption in vivo. FK506 caused a marked increase of bone formation in DBM. However, the conclusion that immunosuppression increases fracture healing warrants further investigation.

Alkaline Phosphatase↗
PubMed1987

New bone formation and bone marrow differentiation induced in rats by extracellular bone matrix implantation: effect of local preirradiation on the process.

Subcutaneous implantation of demineralized diaphyseal rat bone matrix in ACI rats initiates a developmental cascade that results in the formation of new endochondral bone and an associated hematopoietic bone marrow differentiation. Irradiation (1500 rad, 60Co) of the implantation site 24 h prior to implantation suppresses the formation of endochondral bone and bone marrow. All phases of the developmental cascade, including chemotaxis, proliferation, and differentiation, are arrested by the irradiation. Simultaneous implantation with the extracellular matrix of bone marrow, bone, pieces of a four-day-old implant or of thoracic muscle--but not of brain, liver, or spleen tissue--results in the development of endochondral bone and bone marrow at the irradiated site. Concurrent implantation with the extracellular matrix of in vitro growing fibroblasts of marrow or ossicle origin does not restore the developmental cascade.

Alkaline Phosphatase↗
PubMed2005

[Experimental and clinical substantiation of allogenic cortical bone matrix use for treatment of patients with habitual mandibular dislocation].

Cortical bone matrix (CBM) was fixed under the zygomatic arch of 20 experimental rabbits by the titanium wire. CBM transformed into the organotypic bone tissue during 90-180 days, and the transformation processes were more significant if the cortical layer of the inferior border of the zygomatic arch had been removed and CBM had been miotisized. Taking into account good results of the experiment, CBM was applied in clinic for treatment of habitual mandibular dislocation (HMD). The new operative approach to the TMJ and method for HMD using CBM was developed. It is easy to perform, less traumatic and provides reliable long-term results. Of 36 operated joint only one recurrence of the dislocation was observed.

Adolescent↗
PubMed2000

Ultrastructural, cytochemical, and biophysical aspects of mechanisms of bone matrix calcification.

Primary calcification in embryonic ossification occurs as follows: crystallization within matrix vesicles, formation of calcified nodules, and finally the establishment of expansive calcified matrix. However, the participation of the matrix vesicles in other types of bone calcification, such as bone formation during bone remodeling in adults has not been examined sufficiently. We introduce our recent observations on the presence of matrix vesicles in aged bones. In addition, although it is well known that the extracellular fluid supersaturates the calcification crystal, hydroxyapatite, the specific mechanisms by which bone matrix calcify remain unclear. In order to further approach the mechanisms of bone matrix calcification, we also review ultrastructural and localizational alterations of the matrix organics according to the progression of calcification, and an evaluation of mineral micro-environment in the calcifying sites by energy-filter transmission electron microscopy.

Animals↗
PubMed1982

Osteoinduction. Part II: Purification of the osteoinductive activities of bone matrix.

Using a previously described experimental model for demonstration of osteoinduction biological activity of variably prepared fractions of demineralized bone matrix was studied. Sequential extraction of matrix using CaCl2, EDTA, LiCl and water results in an acceleration of the induction process and a reduction of immunological host reaction in the case of xenogenic implants. Application of chaotropic reagents such as guanidinium chloride and sodium thiocyanate has the consequency of lowering the inductive signal. From these results it is likely that noncollagenous constituents of bone matrix play a significant role in osteoinduction.

Alkaline Phosphatase↗
PubMed1996

Identification of osteocalcin as a permanent aging constituent of the bone matrix: basis for an accurate age at death determination.

Age at death determination based on aspartic acid racemization in dentin has been applied successfully in forensic odontology for several years now. An age-dependent accumulation of D-aspartic acid has also recently been demonstrated in bone osteocalcin, one of the most abundant noncollagenous proteins of the organic bone matrix. Evaluation of these initial data on in vivo racemization of aspartic acid in bone osteocalcin was taken a step further. After purification of osteocalcin from 53 skull bone specimens, the extent of aspartic acid racemization in this peptide was determined. The D-aspartic acid content of purified bone osteocalcin exhibited a very close relationship to age at death. This confirmed identification of bone osteocalcin as a permanent, 'aging' peptide of the organic bone matrix. Its D-aspartic acid content may be used as a measure of its age and hence that of the entire organism. The new biochemical approach to determination of age at death by analyzing bone is complex and demanding from a methodologic point of view, but appears to be superior in precision and reproducibility to most other methods applicable to bone.

Adult↗
PubMedDate not supplied

Anterior lumbar interbody fusion with titanium mesh cages, coralline hydroxyapatite, and demineralized bone matrix as part of a circumferential fusion.

BACKGROUND CONTEXT: Anterior lumbar interbody fusion (ALIF) has become one of the primary choices for eliminating motion between vertebral segments in patients with severe discogenic pain and other lumbar pathologies. Autograft is the gold standard for spinal fusion. However, multiple authors have reported complication and morbidity rates associated with iliac crest harvesting to be as high as 25%. Drawbacks to the use of allograft in the anterior column include slower incorporation rates, the possibility for disease transmission, increasing cost resulting from stringent processing and unavailability on a worldwide basis resulting from religious and economic concerns. PURPOSE: To determine the clinical and arthrodesis efficacy of coralline hydroxyapatite as an osteoconductive bone graft substitute in the anterior lumbar spine using a titanium mesh cage. STUDY DESIGN: A series of 50 patients returning for long-term prospective follow-up, implanted with titanium mesh cages filled with coralline hydroxyapatite and demineralized bone matrix for ALIF as part of a circumferential fusion. PATIENT SAMPLE: Long-term clinical and radiographic follow-up were examined for the first 50 patients undergoing this technique by one surgeon. OUTCOME MEASURES: Pain was measured with a visual analog scale and function was measured with the Oswestry Disability Index. METHODS: All 50 patients underwent successful ALIF with titanium mesh cages, coralline hydroxyapatite and demineralized bone matrix, as well as an autologous posterolateral fusion with rigid posterior instrumentation. Patients filled out follow-up questionnaires and appropriate radiographs were taken. RESULTS: A solid fusion rate of 96% was achieved. Mean pain decrease was 60% overall. A total of 70% of all patients either returned to work or to full home activities at a mean of 8 months after surgery. Ninety percent felt the surgery was successful. CONCLUSIONS: The combination of titanium mesh cages, coralline hydroxyapatite and demineralized bone matrix is effective for anterior interbody fusion of the lumbar spine when used as part of a rigidly instrumented circumferential fusion.

Adult↗
PubMed1991

Pleiotropic effects of vitamin D on osteoblast gene expression are related to the proliferative and differentiated state of the bone cell phenotype: dependency upon basal levels of gene expression, duration of exposure, and bone matrix competency in normal rat osteoblast cultures.

Normal rat osteoblasts in culture undergo a developmental sequence consisting of a proliferation period in which high levels of the histone and collagen type I genes are expressed, followed by periods of matrix maturation [high levels of alkaline phosphatase (AP)] and mineralization that signal a high level of production of osteopontin (OP) and osteocalcin (OC). Since these parameters are regulated by vitamin D, the effects of both short term and chronic treatment with 1,25-dihydroxyvitamin D3 were examined during osteoblast growth and differentiation. In acute studies, during the proliferation period, histone mRNA (reflecting DNA synthesis) was inhibited (20-60%). Matrix Gla protein (MGP) and OP mRNA were significantly elevated during proliferation (30- and 15-fold), in contrast to OC which is not expressed and was not induced by hormone treatment. OP and MGP remained stimulated throughout the developmental sequence, but to a lesser degree (from 6- to 10-fold). Collagen and AP mRNA were inhibited by hormone at their peak levels of expression, but were stimulated at their lowest basal levels in the mineralization period. OC expression, which was initiated at the onset of mineralization, was stimulated 13- to 15-fold when basal levels were low, then from 6- to 8-fold by hormone throughout its period of expression. In chronic studies a different profile of gene expression was observed. When hormone treatment was initiated during the proliferation period on day 6, type I collagen and AP expression were suppressed, mineralized nodules did not develop, and induced levels of OP and OC gene expression did not occur. When chronic treatment was initiated on day 20 after the development of a mineralized matrix, OC, but not collagen and OP, levels were stimulated by the hormone. This observation is consistent with the requirement of a competent or mineralized bone matrix for expression of OC. In contrast, MGP expression was stimulated in the chronic vitamin D-treated cultures similar to acute treatments. Taken together these studies demonstrate that vitamin D, a physiological mediator of bone formation and remodelling, can both positively and negatively regulate expression of osteoblast phenotypic markers as a function of duration of hormone treatment and basal levels of gene expression, which is a reflection of bone matrix competency and the differentiated state of the osteoblast.

Animals↗
PubMed1987

Phenotypic modulation of the swarm rat chondrosarcoma induced by morphogenetic bone matrix.

The recognized similarities between developing embryonic tissues and neoplastic cells have led to a number of experimental demonstrations which indicate that inductive microenvironments can alter the malignant phenotype. In postnatal life a morphogenetic cascade resembling endochondral bone development can be induced by s.c. implantation of demineralized diaphyseal bone matrix. We have examined the ability of this microenvironment to alter the phenotype of the transplantable Swarm rat chondrosarcoma in mixed implants. Neoplastic chondrocytes could be distinguished from host cells by nuclear morphometry since the nuclear area of the neoplastic chondrocytes was 2 to 3 times larger than that of comparable host-derived chondrocytes. Through the first 7 days post-implantation tumor cells in the presence of morphogenetically active matrix are morphologically indistinguishable from those implanted with morphogenetically inactivated matrix or implanted by themselves. With the advent of host cell chondrogenesis, however, adjacent neoplastic cells begin to undergo chondrolysis and calcification. Only those cells in the immediate proximity of host morphogenetic foci appear affected. An average of 26.7 +/- 7.0% (SD) of the implant surface areas examined revealed such changes. Chondrosarcoma cells implanted by themselves or in the presence of morphogenetically inactivated bone matrix underwent no such changes. These results suggest that factors released from host cells induced to undergo bone morphogenesis are capable of altering the differentiated phenotype of neoplastic cells.

Animals↗
PubMed1989

[Relevant laboratory diagnostic methods for the evaluation of the osteoinductivity of bone matrix implants].

For the valuation of the osteoinductive efficacy of different bone grafts bears upon increasing the determination of the alkaline phosphatase, the content of calcium, hydroxyproline and protein. We could prove the quantitative differentiation of different prepared bone matrix implants being possible, nevertheless the histological examination is an unavoidable, full of good sense completion.

Alkaline Phosphatase↗
PubMed1975

Reversible extinction of the morphogen in bone matrix by reduction and oxidation of disulfide bonds.

Beta-Mercaptoethanol (beta-ME) or dithiothreitol (DTT) reduction extinguishes the capacity of bone matrix gelatin to produce new bone following implantation in a muscle pouch. If the reducing solution is used in concentrations of 50 mmoles/l or less, the extinction can be partially reversed by bubbling of oxygen through the solution for one hour. Sulfhydryl group blocking reagents prevent reoxidation of reduced bone gelatin, and restoration of the bone morphogenetic property (BMP). Unspecific borohydride reduction at 37 degrees destroys bone yield irreversibly, but at 2 degrees reduction of free aldehyde groups in bone gelatin does not prevent beta-ME and DTT reversible extinction. These observations are interpreted to suggest that the disulphide linkage may be an essential part of the biologically active conformation of either a non-collagenous bone morphogenetic polypeptide firmly bound to collagen or a collagen by-product entrapped within a water insoluble gel matrix.

Animals↗
PubMed2002

Medial artery calcification in ESRD patients is associated with deposition of bone matrix proteins.

BACKGROUND: In non-ESRD patients, recent studies have demonstrated that the process of vascular calcification resembles developmental osteogenesis. Patients with ESRD are known to have excessive vascular calcification, but this has previously been attributed to the non-cell-mediated process of metastatic calcification. METHODS: To determine if the calcification observed in patients with ESRD is related to a cell-mediated process, we removed a piece of inferior epigastric artery at the time of renal transplant. Calcium content of the entire vessel was quantified with spiral computed tomography (CT). The vessel was then examined histologically for calcification and the presence of bone matrix proteins by immunohistochemistry, and medial and intimal thickness quantified by histomorphometry. These findings were correlated with demographic, clinical and laboratory values. RESULTS: The proximal inferior epigastric artery was obtained from 41 patients undergoing renal transplantation, but two were inadequate for histologic examination. Twenty-seven of the remaining vessels had no evidence of calcification by MacNeal's or Alizarin red pH 4.2 staining, five vessels had mild/moderate calcification, and seven had severe calcification, all in the medial layer. Calcification assessed histologically was closely correlated with calcification score as assessed by spiral CT, normalized for vessel weight (P=0.027). Positive immunostaining for the bone matrix proteins osteopontin, type I collagen, bone sialoprotein, and alkaline phosphatase was strongly correlated with calcification (all P < or = 0.001), as was a history of coronary artery disease (P < 0.001), and diabetes (P=0.034). The calcification score by spiral CT correlated with these same factors and the serum phosphorus and calcium x phosphorus product (P=0.032 and 0.037). The location of immunostaining for the bone proteins was strongly associated with the presence of calcification. However, positive immunostaining also was observed in association with disorganization of the vascular smooth muscle cells in the medial layer due to deposition of a matrix-like substance, prior to overt calcification. CONCLUSIONS: In patients with ESRD undergoing renal transplantation, vascular calcification of the medial layer of the inferior epigastric artery is common (44%), can be detected by spiral CT, and is associated with deposition of bone matrix proteins. This implies an active cell-mediated process, raising hope that directed intervention can arrest this process.

Adult↗
PubMed1981

Effect of 1 alpha-hydroxyvitamin D3 on cancellous bone matrix. An experimental study on adult rats.

Two groups of adult male rats were treated perorally for 6 weeks with 0.1 microgram and 1.0 microgram of 1a-hydroxyvitamin D3 (1a-OH-D3), respectively. The effect of the treatment on cancellous bone matrix was studied by chemical analysis and morphometric measurements. The effect of the 1.0 microgram dose on the inorganic composition, and on the calcification of the cancellous bone matrix, was significantly more pronounced, decreasing the amount of glycosaminoglycans. The lower dose level, 0.1 microgram of 1a-OH-D3, increased the collagen metabolism, whereas the higher dose level did not. The amount of cancellous bone determined morphometrically increased significantly during treatment with both dose levels. 1a-OH-D3, converted in the organism to the hormonal form 1.25 (OH)2D3, induces new bone formation, probably by direct influence on the cancellous bone tissue itself.

Animals↗
PubMed1988

Response of bone marrow stroma cells to demineralized cortical bone matrix in experimental spinal fusion in rabbits.

The effect of autogeneic bone marrow (BM) cells and allogeneic demineralized bone matrix (DBM), alone or combined, as transplantation materials was studied in an experimental posterior thoracic spinal fusion model in rabbits. Transplantation of composite grafts composed of BM and DBM showed the first signs of fusion between two spinal segments after four weeks, reaching 86% after 20 weeks. Late fusion results achieved with DBM alone were similar. The capacity of BM per se to build up a spinal fusion was insignificant. Calcified tissue, documented roentgenographically, was shown to develop locally with time, and the earliest bridging of an interspace was noted after four weeks. Histologically, formation of new bone and cartilage was observed after two weeks, showing mature lamellar bone formation between thoracic segments after 20 weeks. Furthermore, increased 45Ca activity was still observed in the fused tissues after 20 weeks. Although, with grafting materials used, this model for experimental spinal fusion gave promising results, further investigations with other fusion techniques could give still better effects.

Animals↗
PubMed1992

Trans-differentiation of hypertrophic chondrocytes into cells capable of producing a mineralized bone matrix.

Trans-differentiation of hypertrophic chondrocytes into bone-forming cells was observed when femurs from 14-day-old chick embryos were cut through the region of hypertrophic cartilage and the separated pieces were cultured for 2-18 days. Inside many chondrocytic lacunae a new matrix was present which had the staining characteristics of bone matrix including birefringence and the capacity to mineralize. The cells within the lacunae had the characteristics of osteoblasts, such as alkaline phosphatase activity and positive immunocytochemical staining for osteocalcin, osteonectin, osteopontin and type I collagen. Chondrocyte necrosis and empty lacunae were only observed immediately at the cut edge, and in that region no bone-forming cells were present inside the lacunae. Where bone-matrix was present, the lacunae had remained intact, the cells were viable and no evidence of cell migration was observed. This suggested that the bone-forming cells had originated from the hypertrophic chondrocytes. The temporal sequence of events was followed closely. Two days following the cut only a few chondrocytes showed a positive reaction for osteocalcin, osteonectin, osteopontin and the type I collagen. At that time no such reaction product was observed in the chondrocytes of uncut femurs. Many hypertrophic chondrocytes divided, as shown by tritiated thymidine incorporation. The rate of cell division increased between 2-6 days, when several smaller basophilic cells were present inside the lacuna instead of the single hypertrophic chondrocyte. These cells expressed alkaline phosphatase activity, were positive for fibronectin, the above non-collagenous bone proteins and type I collagen. The bone matrix that was observed after 6-18 days was initially confined to the inside of the chondrocytic lacunae, but later spread beyond the lacunar confines. The bone proteins were still associated with the bone-forming cells, but fibronectin was absent when matrix formation was evident. Mineralization of the intra-lacunar osteoid took place after 12-18 days. It is speculated that the trans-differentiation was initiated by disruptions of the normal cell-cell associations.

Alkaline Phosphatase↗
PubMed1991

The concept of osseointegration and bone matrix expression.

Osseointegration has been defined as the direct structural and functional connection between ordered, living bone and the surface of a load-carrying implant. To date, this concept has been described by descriptive histological and ultrastructural criteria but not by biochemical means. This review evaluates the basic science work performed on this concept and then applies the concept to the principle of osseous healing. Specific studies are cited where alterations in the healing response are due to clinical management of implant placement and how studies of surface properties may lead to further insights on implant design and prognosis. In addition, a review of bone expression as a function of in vitro stress applications is given. This is followed by an indepth review of the collagens and noncollagenous proteins, described to date, within isolated bone matrix. It is this collagenous matrix (especially type I) that is described as being close to and oriented with a glycoprotein component next to the implant surface. In turn, the large family of noncollagenous proteins are important in mediating bone proliferation, matrix accumulation, orientation, mineralization, and turnover. This section is followed by a discussion of specific growth factors as they may relate to osseous healing around an implant.

Animals↗
PubMed1999

Noncollagenous bone matrix proteins, calcification, and thrombosis in carotid artery atherosclerosis.

Advanced atherosclerosis is often associated with dystrophic calcification, which may contribute to plaque rupture and thrombosis. In this work, the localization and association of the noncollagenous bone matrix proteins osteonectin, osteopontin, and osteocalcin with calcification, lipoproteins, thrombus/hemorrhage (T/H), and matrix metalloproteinases (MMPs) in human carotid arteries from endarterectomy samples have been determined. According to the recent American Heart Association classification, 6 of the advanced lesions studied were type V (fibroatheroma) and 16 type VI (complicated). Osteonectin, osteocalcin, and osteopontin were identified by monoclonal antibodies IIIA(3)A(8), G12, and MPIIIB10(1) and antiserum LF-123. Apolipoprotein (apo) AI, B, and E; lipoprotein(a); fibrinogen; fibrin; fragment D/D-dimer; MMP-2 (gelatinase A); and MMP-3 (stromelysin-1) were identified with previously characterized antibodies. Calcium phosphate deposits (von Kossa's stain) were present in 82% of samples (3 type V and 15 type VI). Osteonectin was localized in endothelial cells, SMCs, and macrophages and was associated with calcium deposits in 33% of type V and 88% of type VI lesions. Osteopontin was distributed similarly to osteonectin and was associated with calcium deposits in 50% of type V and 94% of type VI lesions. Osteocalcin was localized in large calcified areas only (in 17% of type V and 38% of type VI lesions). ApoB colocalized with cholesterol crystals and calcium deposits. Lipoprotein(a) was localized in the intima, subintima, and plaque shoulder. Fibrin (T/H) colocalized with bone matrix proteins in 33% of type V and 69% of type VI lesions. MMP-3 was cytoplasmic in most cells and colocalized with calcium and fibrin deposits. MMP-2 was less often associated with calcification. The results of this study show that osteonectin, osteopontin, and osteocalcin colocalized with calcium deposits with apoB, fibrin, and MMP-3 in advanced, symptomatic carotid lesions. These data suggest that the occurrence of T/H might contribute to dystrophic arterial calcification in the progression and complications of atherosclerosis.

Arteriosclerosis↗
PubMed2004

The effect of chicken, pigeon, and turkey demineralized bone matrix (DBM) implanted in ulnar defects fixed with the intramedullary-external skeletal fixator (IM-ESF) tie-in in pigeons (Columba livia): histological evaluations.

Avian demineralized bone matrix (ADBM) powder prepared from chicken, pigeon, and turkey sources induced bone formation via endochondral and intramembranous processes, as in mammalian studies. There were no significant differences in percentage of new bone, percentage of cartilage, surface-forming osteoblast area, or osteoclast count between gaps treated with chicken, pigeon, and turkey DBM. However, there was a significantly (p<0.05) higher percentage of inflammatory area in gaps treated with chicken DBM than in gaps treated with pigeon DBM.

Animals↗