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PubMed1998

Prosthesis-bone interface.

In this overview, which is based on selected books and reviews, the microscopic appearances of prosthesis-bone interfaces resulting from clinically relevant implantation techniques are highlighted. The following techniques are distinguished to insert and attach prostheses in the recipient bone: impaction into bone, primary mechanical interlocking, cement fixation, bone ongrowth and secondary mechanical interlocking with bioinert materials, and enhanced bone ongrowth and bone bonding to bioactive materials. The resulting typical histomorphologies of orthopedic and dental prostheses-bone interfaces are described and illustrated from the author's studies employing light, fluorescence, and backscattered electron microscopy, and corresponding microradiographs of undecalcified ground sections of bone and implants. Special emphasis is given to the mineralization-demineralization kinetics of the interfacial bone matrix interacting with specific surface reactions of some implant materials. Consequently, the distinction between bioinert and bioactive prosthetic materials is critically analyzed.

Animals↗
PubMed2001

Prefabricated vascularized bone flap: a tissue transformation technique for bone reconstruction.

In this study, an attempt was made to transform a muscle vascularized pedicle raised on host vessels into a vascularized bone flap, using recombinant human bone morphogenetic protein 2 (rhBMP-2). The purpose of this study was to produce new bone vascularized in nature to increase the survival rate of the subsequently grafted bone and to fabricate the newly formed bone into the desired shape. Silicone molds in the shape of a rat mandible were used to deliver rat bone matrix impregnated with or without rhBMP-2. A muscle pedicle the same size as the mold was raised on the saphenous vessels in the rat thigh and then sandwiched in the center of the silicone molds. The molds were sliced in half and each section was filled with rat bone matrix that was impregnated either with 25 microg of rhBMP-2 for the experimental group or with diluting material alone for the control group. The sandwiched flaps were then secured by tying them to the adjacent muscles and were harvested at 2 and 4 weeks after surgery. Three and six rats were used in the control and experimental groups at each time point, respectively. Bone formation was assessed in the ex vivo specimens by macroscopic, radiologic, and histologic evaluation. Macroscopically, the continuation of the vascular pedicle was clearly visible for both the control and experimental muscle flaps. However, no evidence of muscle-tissue transformation was observed in the control flaps, whereas all the flaps treated with rhBMP-2 produced new bone that replicated the shape of the mold exactly and had saphenous vessels supplying the newly formed bone. This study demonstrates that this experimental model has the potential to be therapeutically applied for effective bone reconstruction.

Animals↗
PubMed2006

P-15 small peptide bone graft substitute in the treatment of non-unions and delayed union. A pilot clinical trial.

Treatment of non-unions and delayed unions often requires osteogenic material. Recently, a biomimetic bone matrix that simulates the cellular environment of hard tissue, identified as P-15, was introduced to the orthopaedic community. A total of 22 patients with mal-union or delayed union fractures was treated from June 2000 to October 2003 with P15- bone graft substitute (P15-BGS) in the site of fracture and mostly with internal fixation. Patients were examined by independent radiographic analysis. Assessment criteria included time elapsed until bone bridging and time to full consolidation. In addition, histological assessment of the callus was done at the time of recovery of metal implants in five patients. Full consolidation was achieved in 90% (20 out of 22) of the patients treated with P15-BGS. The average time for full consolidation was 4.2 months. Histological assessment of the fracture callus in five of the patients confirmed the positive clinical and radiographic results. P15-BGS appears to offer a safe, economical and clinically useful alternative to autograft in the repair of ununited fractures. These results compare favourably with those in the published literature as an alternative to autograft.

Adolescent↗
PubMed1983

The role of calcium in the mechanical behaviour of bone.

Plugs of fresh post mortem human patellar subchondral bone were soaked for three weeks in an organic solvent (ethanol) which contained a chelating agent (EDTA). This technique selectively removes the calcified inorganic component without disrupting the structure of the remaining bone matrix. These plugs, together with untreated plugs as controls, were treated in unconfined compression at a fixed strain rate and allowed to relax to evaluate the contribution made by the calcium component to the physical and time-dependent properties of subchondral bone.

Adolescent↗
PubMed1987

High doses of the diphosphonate EHDP for the prevention of heterotopic ossification. An experimental and clinical study.

The effect of Ethane-1-Hydroxyl-1, 1-Diphosphonate (EHDP) on experimental and clinical heterotopic ossification was studied. Demineralized cortical bone matrix was implanted in the abdominal wall of three groups of adult male rats. Two groups received injections amounting to 5 and 20 mg/kg/day of EHDP, respectively, and a control group received placebo. The lower dose of EHDP had no effect on bone formation, whereas the higher dose resulted in a marked reduction in ash content and 45Ca uptake in the implants. Inhibitory effects on heterotopic bone and serum alkaline phosphatase activity were observed when treating with high doses (50 mg/kg/day) a paraplegic patient following resection of para-articular ossifications around the hips. The effect of EHDP on bone formation is interpreted as reflecting a dose-dependent interference with the deposition of hydroxyapatite crystals in the bone matrix.

Adult↗
PubMed2001

Bisphosphonate acts on osteoclasts independent of ruffled borders in osteosclerotic (oc/oc) mice.

We examined the effects of a third generation bisphosphonate [YM-175; disodium dihydrogen (cycloheptylamino)-methylene-1,1-bisphosphonate] on osteoclasts in osteosclerotic (oc/oc) mice to elucidate the cellular mechanism for incorporation of the bisphosphonate. Osteoclasts of oc/oc mice were in direct contact with bone matrix but devoid of ruffled borders. Tartrate-resistant acid phosphatase (TRAPase) showed spotty localization intercellularly, whereas vacuolar H(+)-ATPase (V-ATPase) immunoreactivity was observed homogeneously in the cytoplasm. Upon injection of bisphosphonate, most osteoclasts lost cell polarity and were detached from bone surfaces. The detached osteoclasts underwent apoptosis as characterized by condensation of chromatin, absence of Golgi apparatus, and formation of many vesicles in the cytoplasm. Both TRAPase and V-ATPase were evenly distributed in the cytoplasm. The pyknotic nuclei of osteoclasts revealed DNA fragments as evidenced by the terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling (TUNEL) method. The results indicate that osteoclasts lacking ruffled borders in oc/oc mice incorporated the bisphosphonate from a site different from ruffled borders and that bisphosphonate may directly affect osteoclasts without mediating its deposition to the bone matrix.

Animals↗
PubMed1999

Comparison of recombinant and purified human bone morphogenetic protein.

Clinically, it would be more convenient to use recombinant than purified preparations of bone morphogenetic protein (BMP). Recently, recombinant human BMP (rhBMP) has attracted the attention of many investigators, but it has not been fully characterized. We examined the bone-inducing activity of rhBMP-2 and compared it with that of purified BMP derived from human bone matrix (phBMP). Two, 10, or 50 microg of rhBMP-2 or phBMP was mixed with 3 mg of atelopeptide type I collagen (carrier), and specimens were implanted in the calf muscles of Wistar rats (n=5 in each group). Four weeks later, new bone had formed in all the rhBMP-2- and phBMP-implanted muscles and was visible radiographically and histologically. The quantitative analysis indicated that the activity of rhBMP-2 was less than one tenth that of phBMP. It is necessary to find out why rhBMP-2 has fewer activities than phBMP.

Alkaline Phosphatase↗
PubMedDate not supplied

Efficacy of allogenic bone implants in a series of consecutive elective foot procedures.

To show the efficacy of an allogenic bone graft in elective foot surgery, the authors report on 39 consecutive procedures in which allograft was implanted in 26 patients during a 30-month period. These procedures were performed for a variety of conditions, including arthrodesis, segmental lengthening, and treatment of nonunion. Allograft material consisted of freeze-dried tricortical iliac crest or demineralized bone matrix used either alone or as a composite. Allograft incorporation in all surgical procedures was retrospectively analyzed. Of 39 consecutive implant procedures, there were 38 healed sites (97%) and 1 nonunion (3%). After radiographic and clinical evaluation of allograft incorporation, the authors conclude that allogenic bone graft is a viable option for a multitude of foot conditions.

Adolescent↗
PubMed2003

Maspin expression inhibits osteolysis, tumor growth, and angiogenesis in a model of prostate cancer bone metastasis.

Emerging evidence indicates that tumor-associated proteolytic remodeling of bone matrix may underlie the capacity of tumor cells to colonize and survive in the bone microenvironment. Of particular importance, urokinase-type plasminogen activator (uPA) has been shown to correlate with human prostate cancer (PC) metastasis. The importance of this protease may be related to its ability to initiate a proteolytic cascade, leading to the activation of multiple proteases and growth factors. Previously, we showed that maspin, a serine protease inhibitor, specifically inhibits PC-associated uPA and PC cell invasion and motility in vitro. In this article, we showed that maspin-expressing transfectant cells derived from PC cell line DU145 were inhibited in in vitro extracellular matrix and collagen degradation assays. To test the effect of tumor-associated maspin on PC-induced bone matrix remodeling and tumor growth, we injected the maspin-transfected DU145 cells into human fetal bone fragments, which were previously implanted in immunodeficient mice. These studies showed that maspin expression decreased tumor growth, reduced osteolysis, and decreased angiogenesis. Furthermore, the maspin-expressing tumors contained significant fibrosis and collagen staining, and exhibited a more glandular organization. These data represent evidence that maspin inhibits PC-induced bone matrix remodeling and induces PC glandular redifferentiation. These results support our current working hypothesis that maspin exerts its tumor suppressive role, at least in part, by blocking the pericellular uPA system and suggest that maspin may offer an opportunity to improve therapeutic intervention of bone metastasis.

Animals↗
PubMed2006

Arthroscopic ankle arthrodesis: factors influencing union in 39 consecutive patients.

BACKGROUND: Arthroscopic ankle arthrodesis is an effective alternative to open techniques with established advantages in select patient populations. The purpose of this study was to evaluate patients who had arthroscopic ankle arthrodesis for end-stage arthritis with minimal to no deformity of the ankle and to report factors influencing union. METHODS: Thirty-nine consecutive patients had arthroscopic ankle arthrodesis between 1994 and 2003. Clinical records and radiographs were retrospectively reviewed to evaluate variables that could predispose patients to nonunion. Union outcomes were correlated with etiology of arthritis, ankle deformity, medical co-morbidities, and the use of demineralized bone matrix or platelet-rich plasma. Arthroscopic ankle arthrodesis was accomplished with a consistent technique using crossed transmalleolar cannulated screw fixation. RESULTS: Thirty-four of 39 patients (87.2%) achieved radiographic and clinical union. The average time to fusion was 47 (range 37 to 70) days. Poor bone quality and inherent positional ankle deformity were identified as risk factors for nonunion. Patients who smoked, had diabetes mellitus, peripheral neuropathy, or other medical co-morbidities attained ankle union in nearly all cases. In obese patients, there was an observed trend towards ankle nonunion (relative risk 5.81, p = 0.049, Fisher's Exact test). The addition of demineralized bone matrix or platelet-rich plasma did not improve the rate of ankle union. Aside from nonunion, 10 patients developed minor complications. CONCLUSION: Arthroscopic ankle arthrodesis achieves high union rates, facilitates short time to union, and permits rapid patient mobility. Careful patient selection is important for the procedure. Synthetic allograft or platelet-rich plasma did not enhance the fusion rate. Obese patients showed a trend towards nonunion in this series.

Adult↗
PubMed1997

Cystatin C, and inhibitor of bone resorption produced by osteoblasts.

The effects of human cystatin C on bone resorption, enzyme release, osteoclast generation, bone cell proliferation and bone matrix protein biosynthesis have been examined in different in vitro systems. The effects of cystatin C were compared with those of calcitonin and E 64 (trans-Epoxysuccinyl-L-leucyl-amido-(4-guanidino)butane). Recombinant human cystatin C and E 64 dose dependently inhibited the mobilization of 45Ca and the release of 3H (from [3H]-proline-labelled bones) in mouse calvariae stimulated to resorb by parathyroid hormone (PTH) or 1,25(OH)2-vitamin D3. Cystatin C and E 64 also inhibited the release of 45Ca from bones stimulated by thrombin, interleukin-1 and prostaglandin E2. In PTH-stimulated bones, the inhibitory action of cystatin C and E 64 on 45Ca release was observed after 6-9 h, whereas the inhibitory effect on 3H release was seen after just 2 h. In contrast, calcitonin caused an inhibition of both 45Ca and 3H release which was seen after 2 h. The PTH-stimulated release of the lysosomal enzymes was not affected by cystatin C and E 64, whereas calcitonin caused a significant inhibition. In contrast to calcitonin, cystatin C did not affect PTH-stimulated enhancement of osteoclast generation in the mouse calvariae. Using Western blot analysis and radioimmunoassay, we demonstrated that mouse calvarial bones and MC3T3-E1 cells produce cystatin C. These data show that cystatin C is synthesized by bone cells and that recombinant human cystatin C inhibits bone resorption in vitro without affecting bone cell proliferation, bone matrix formation or osteoclast generation. The mechanism seems to be due primarily to inhibition of the activity of osteoclastic proteolytic enzymes released into the resorption lacunae.

Acetylglucosaminidase↗
PubMedDate not supplied

Case report: massive osteolysis in a case of rheumatoid arthritis: clinical, histologic and biochemical findings.

A 54-year-old male with a 10-year history of seropositive rheumatoid arthritis subsequently developed generalized osteoporosis, multiple cervical spine subluxation, vertebral collapses, and massive osteolysis of the humeral and femoral heads and carpal bones. These lesions were accompanied by neurologic manifestations in both the upper and lower extremities. Bone matrix collagen and noncollagenous proteins in this rare syndrome were analyzed. The pathogenesis of this rare phenomenon is discussed.

Arthritis, Rheumatoid↗
PubMed1993

Bone remodeling and the osteoclast.

Bone remodeling is a process initiated by the osteoclast, and thus, its understanding is prerequisite to regulation of bone turnover. The last decade has witnessed major advances in our understanding of osteoclast biology, specifically as relates to the ontogeny of the cell and the mechanisms by which it degrades bone. It is now possible to isolate and generate osteoclasts and maintain them in relative purity. Using these models, a number of laboratories have shown that ion transport by the osteoclast plays a major role in its ability to resorb bone. Furthermore, osteoclast-bone matrix attachment, mediated at least in part by integrins, is pivotal to the resorptive process. These discoveries are likely to lead to insight into control of the remodeling process.

Animals↗
PubMed1983

Immunohistochemical demonstration of parathyroid hormone binding to specific cell types in fixed rat bone tissue.

Deparaffinized sections of fixed decalcified neonatal rat radii were incubated in bovine PTH (bPTH; 1-10 MRC units/ml) or in PTH-solvent. They were then stained for PTH by the peroxidase-antiperoxidase method using guinea pig antiserum to bPTH and the substrate 3,3'-diaminobenzidine-H2O2. Staining caused by nonspecific binding of PTH to the bone matrix and the glass slides supporting the sections was eliminated completely by preincubation of the sections in 100% normal goat serum. Cross-reactivity of the antiserum to erythrocytes was eliminated by preabsorption of the antiserum with fixed rat erythrocytes. After the cross-reactivity of the anti-PTH antiserum to erythrocyte components and the nonspecific binding of PTH to bone matrix were eliminated, we were able to demonstrate intense staining over the cytoplasm of the osteoclasts in rat radii sections incubated with PTH. Less intense staining was observed over the osteocytes, periosteal osteoblasts, and, possibly, the endosteal osteoblasts. An explanation for this differential staining could be that osteoclasts have a greater receptor number and/or a greater receptor affinity for the bPTH than do osteocytes and osteoblasts. This study demonstrates that binding of PTH to bone tissue can be localized in all identifiable osteoclasts, osteocytes, and osteoblasts, and thus suggests that all three cell types can interact directly with PTH.

Animals↗
PubMed1980

Effect of 1 alpha-hydroxycholecalciferol on the skeletal mineral metabolism and bone morphogenesis.

Administered 1 alpha-OH-D3 is hydrolyzed in liver and then converted to active 1 alpha, 25-(OH)2-D3. An increased serum calcium content was observed in rats administered 1 alpha-OH-D3. No calcium and magnesium increase was noticed in cortical bone due to 1 alpha-OH-D3 administration. Morphogenesis of bone and cartilage in implanted bone matrix in a group of 1 alpha-OH-D3 administered host rats seemed relatively increased to a slight extent.

Aging↗
PubMed2005

Differential regulation of osteoblast activity by Th cell subsets mediated by parathyroid hormone and IFN-gamma.

Bone loss is a typical pathological feature of chronic inflammatory bone diseases including rheumatoid arthritis, in which CD4 effector T cells play critical roles. We found that activated mouse Th2 and not Th1 cells produced the parathyroid hormone (PTH). Unlike in the parathyroid cells, PTH expression in Th2 cells was not regulated by the fluctuation of calcium level, but rather it required the full activation of the T cells. Although PTH was expressed in immature Th2 cells, and its receptor was transiently expressed during Th1 and Th2 cell differentiation, PTH did not significantly affect the outcome of the differentiation. In primary osteoblasts cultured in Th2 cell condition medium, the alkaline phosphatase (ALP) activity was maintained at a basal level. However, antagonizing PTH in the condition medium resulted in a significant reduction of the ALP activity. These results demonstrated an important role of the Th2 cell-derived PTH in maintaining the bone-forming activity of the osteoblasts under inflammatory conditions. In osteoblasts cultured in the Th1 cell condition medium, the ALP activity was significantly suppressed. Neutralizing IFN-gamma alleviated the suppression. Conversely, treatment of osteoblasts with IFN-gamma suppressed the ALP activity. Unlike ALP, expression of the major bone matrix proteins by the osteoblasts was only minimally affected by either Th1 or Th2 cytokine environment. In addition, the Th2 cytokine environment also regulated to expression of receptor activator of NF-kappaB ligand and osteoprotegerin through both PTH-dependent and -independent mechanisms. Our study therefore identified new regulatory events in bone remodeling under inflammatory conditions.

Alkaline Phosphatase↗
PubMed2006

Nicotine treatment induces expression of matrix metalloproteinases in human osteoblastic Saos-2 cells.

Tobacco smoking is an important risk factor for the development of severe periodontitis. Recently, we showed that nicotine affected mineralized nodule formation, and that nicotine and lipopolysaccharide stimulated the formation of osteoclast-like cells by increasing production of macrophage colony-stimulating factor (M-CSF) and prostaglandin E2 (PGE2) by human osteoblastic Saos-2 cells. In the present study, we examined the effects of nicotine on the expression of matrix metalloproteinases (MMPs), tissue inhibitors of matrix metalloproteinases (TIMPs), the plasminogen activation system including the component of tissue-type plasminogen activator (tPA), urokinase-type PA (uPA), and PA inhibitor type 1 (PAI-1), alpha7 nicotine receptor, and c-fos. We also examined the effect of the nicotine antagonist D-tubocurarine on nicotine-induced expression of MMP-1. Gene expression was examined using real-time polymerase chain reaction (PCR) to estimate mRNA levels. In addition, expression of the MMP, TIMP, uPA, tPA, and PAI-1 proteins was determined by Western blotting analysis. Nicotine treatment caused expression of MMP-1, 2, 3, and 13, but not MMP-14, to increase significantly after 5 or 10 d of culture; MMP-14 expression did not change through day 14. Enhancement of MMP-1 expression by nicotine treatment was eliminated by simultaneous treatment with D-tubocurarine. In the presence of nicotine, expression of uPA, PAI-1, or TIMP-1, 2, 3, or 4 did not change over 14 d of culture, whereas expression of tPA increased significantly by day 7. Nicotine also increased expression of the alpha7 nicotine receptor and c-fos genes. These results suggest that nicotine stimulates bone matrix turnover by increasing production of tPA and MMP-1, 2, 3, and 13, thereby tipping the balance between bone matrix formation and resorption toward the latter process.

Cell Line, Tumor↗
PubMed2006

Comparative study of cryopreserved bone tissue and tissue preserved in a 98% glycerol solution.

OBJECTIVE: To compare the bone graft cryopreservation method (at -80 degrees C) with a preservation method using a 98% glycerol solution at room temperature (10 degrees C-35 degrees C), by testing the antibacterial and fungal effects of 98% glycerol and comparatively analyzing the observed histological changes resulting from the use of both methods. METHOD: This study was of 30 samples of trabecular bone tissue from 10 patients undergoing total hip arthroplasty. Each femoral head provided 3 samples that were randomized into 3 groups, namely, the control group, the cryopreserved group, and the group preserved in a 98% glycerol at room temperature for 1 year. The samples were submitted to histomorphologic, cell feasibility, and microbiologic analyses. The results were statistically analyzed using the McNemar test, with a statistical significance index of 0.05. RESULTS: Values obtained using the McNemar test to compare probability distributions of histomorphologic variables (mature or lamellar bone, immature bone, and necrosis) and cell feasibility (osteoblasts and osteoclasts) indicated that there is no difference between the distributions of variables under the 3 experimental conditions. Microbiological analysis of the 98% glycerol solution and bone fragments from samples stored for 1 year at room temperature did not show bacterial or fungal growth. The histological and microbiological investigation were performed at 2 different time points: immediately after the sample processing and after 1 year. CONCLUSION: The method used to preserve bone grafts kept in 98% glycerol at room temperature (10 degrees C-35 degrees C) was similar to cryopreservation in terms of bone matrix preservation; no bacteria or fungi were found in the samples.

Bone Matrix↗