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Grafting long bone fractures with demineralized bone matrix putty enriched with bone marrow: pilot findings.

In this pilot study, the preliminary effectiveness of a composite graft consisting of demineralized bone matrix (DBM) putty (Grafton DBM) and aspirated bone marrow was evaluated for treating long bone fractures. Patients were ssigned randomly to treatment with the DBM putty composite (n = 10) or iliac crest autograft (n = 8), and had a minimum of 12 months of radiographic follow-up. Ninety percent of DBM patients (9/10) achieved full bone formation compared to 75% of autograft patients (6/8) (P = .41). Additionally, all 10 DBM patients were healed compared with 63% of autograft patients (5/8) (P = .07). These findings suggest that DBM putty enriched with bone marrow may be comparable to autograft for treating long bone fractures.

Adult↗

In search of the ideal bone morphogenetic protein delivery system: in vitro studies on demineralized bone matrix, purified, and recombinant bone morphogenetic protein.

The clinical use of recombinant bone morphogenetic protein (rBMP) is limited by the lack of a suitable delivery system. The bone morphogenetic protein (BMP) delivery system provided by nature is highly effective, and by studying purified BMP (BMP/NCP) and demineralized bone matrix (DBM), it may be possible to learn how to emulate nature's success. The current study used an in vitro muscle cell model to study the activity of BMP/NCP and DBM and the effects of extracellular matrix on BMP activity. C2C12 cells transiently exposed to recombinant human BMP-4 (rhBMP-4) rapidly increased their alkaline phosphatase (AP) activity to day 5, after which it steadily declined. Cells exposed to BMP/NCP or DBM continued to increase their AP activity over the 14-day culture. If BMP/NCP was treated to remove a 22-kd protein, it became water-soluble and exhibited a similar activity pattern to rhBMP-4. Cells cultured on collagen type I, fibronectin, and hyaluronic-coated surfaces demonstrated increased AP activity when exposed to rhBMP-4 or BMP/NCP compared with cells cultured on bovine serum albumin or poly-l-lysine. These results suggest that the natural BMP delivery system operates both by binding to the BMP molecule and slowly releasing it into the extracellular milieu and by interacting with the responding cells through cell-matrix receptors to enhance the cellular response to BMP.

Alkaline Phosphatase↗

Periodontal repair in dogs: effect of allogenic freeze-dried demineralized bone matrix implants on alveolar bone and cementum regeneration.

The objective of this study was to evaluate alveolar bone and cementum regeneration following surgical placement of an allogenic, freeze-dried, demineralized bone matrix (DBM) cortical strip implant. Critical size, supraalveolar periodontal defects were surgically created around the second, third, and fourth mandibular premolar teeth in eight mongrel dogs. Contralateral jaw quadrants in six animals were randomly assigned to receive the DBM implant, or serve as surgical control. Two additional animals received bilateral DBM implants. Flaps were coronally advanced to submerge teeth and implants, and sutured. Three animals were exited from the study due to extensive early wound failure. Remaining animals were sacrificed at 8 weeks postsurgery. Histometric recordings included defect height, bone regeneration/DBM implant height, cementum regeneration height, root resorption, and ankylosis. Large areas of unresorbed DBM exhibiting fragmentation and empty osteocyte lacunae were observed adjacent to new bone formation, or bone formation was observed adjacent to or within the implant, often exhibiting ankylosis. Cementum regeneration appeared enhanced in shelter of the DBM implant. Histometric recordings (mean+/-SD) for DBM and control defects, respectively, were: defect height, 4.8+/-0.2 mm and 4.4+/-0.2 mm; bone regeneration/DBM implant height, 4.0+/-1.3 mm and 1.2+/-0.6 mm; cementum regeneration height, 1.4+/-0.4 mm and 0.7+/-0.2 mm; root resorption, 0.5+/-0.3 mm and 1.2+/-0.3 mm; and ankylosis, 0.5+/-0.2 mm and 0.1+/-0.1 mm without statistically significant differences between experimental conditions (N=3). Within the limitations of this study, the histologic observations suggest that surgical implantation of allogenic, freeze-dried DBM cortical strip implants may have a potential to support cementum regeneration, possibly by providing conditions for guided tissue regeneration, however, alveolar regeneration appears unpredictable.

Alveolar Bone Loss↗

[Bone matrix proteins].

Bone matrix is composed of collagen and non-collagenous proteins. The collagen is mainly type I collagen. Characteristics of bone collagen are in posttranslational modifications and utilization of transcriptional elements in the promoter. The non-collagenous proteins are acidic Ca-binding proteins: bone Gla protein(BGP), bone sialoprotein (BSP), osteopontin, osteonectin etc. BGP and BSP are specific to bone, and other proteins are present also in non-mineralized tissues. BGP functions in suppression of excessive mineralization. BSP and osteopontin are sialoproteins containing a RGD cell-attachment sequence and poly(acidic amino acid) sequences. BSP is present in sites of bone formation. Osteopontin is involved in attachment of osteoclasts to bone surface.

Animals↗

Effect of preimplantation treatment on the bone-forming potential of decalcified allogeneic and xenogeneic bone-matrix implants.

Bone-forming property of 0.6 M HCl decalcified (a) allogeneic bone matrix preserved in 70% alcohol, (b) allogeneic bone matrix preserved in anaesthetic ether, (c) allogeneic 'Ossein' provided by the Leather Research Institute, Madras, and (d) xenogeneic bone-matrix preserved in alcohol was studied by fitting the implants in surgically created complete circumferential osteo-periosteal gaps in the ulna of rabbits. Bone formation was assessed radiologically, macroscopically, histologically, and by tetracycline fluorescence up to 16 postimplantation weeks. Successful bridging of the gap by new bone formation was observed in 75% of (a) and 28.6% of (d) preserved up to 2 weeks. Ether-preserved implants did not induce bone formation. The 'Ossein' implants remained as inert material neither invaded by host cells nor inducing any bone formation. The xenogeneic implants exhibited local immune response which was probably responsible for poor osteogeneic response. Bone forming quality of bone-matrix implants appears to be influenced by the chemical treatment during preparation and preservation, host cellular response and immune reaction invoked by the implant.

Animals↗

The effect of decalcified bone matrix on the osteogenic potential of bone marrow.

Rabbit bone marrow cells were cultured in diffusion chambers with or without decalcified bone matrix. The chambers were assayed after 28 days for alkaline phosphatase activity, deoxyribonucleic acid (DNA), calcium, and phosphorus contents. Morphologically, marrow cells incubated with or without matrix differentiated to form bone and cartilage. With bone matrix, the calcium and phosphorus contents of chambers were significantly higher than control chambers. Alkaline phosphatase activity and DNA content were not influenced by inclusion of bone matrix. These results indicate that bone matrix constituents exert a stimulatory effect on bone formation from marrow cells. This osteogenic stimulation could be due to the influence of an osteoinductive factor and/or to stimulation of osteoprogenitor cells known to be present in the marrow.

Alkaline Phosphatase↗

Effects of fixation and decalcification on the immunohistochemical localization of bone matrix proteins in fresh-frozen bone sections.

To examine the stability of bone matrix proteins for crystal dislocation, the immunolocalization of type I collagen, bone sialoprotein, and osteopontin was investigated during different stages of fixation and decalcification. Four-week-old rat femurs were rapidly frozen, and were sectioned without fixation or decalcification. Thereafter, following or bypassing fixation in 4% paraformaldehyde, these sections were decalcified in 5% EDTA for 0-5 min. Before decalcification, marked radiopacity of bone matrix was observed in contact microradiography (CMR) images, and electron probe microanalysis (EPMA) demonstrated intense localization for phosphorus and calcium. In fixed and unfixed sections without decalcification, immunolocalization of bone matrix proteins were almost restricted to osteoid. After 1 min of decalcification, reduced radiopacity was apparent in the CMR images, and less phosphorus and calcium was observed by EPMA, which completely disappeared by 5 min decalcification. After 3-5 min of decalcification, unfixed sections showed that these proteins were immunolocalized in bone matrix, but were not detectable in osteoid. However, fixed sections demonstrated that these were found in both bone matrix and osteoid. The present findings suggest that bone matrix proteins are embedded in calcified matrix which is separated from the aqueous environment and that they hardly move, probably due to firm bonding with each other. In contrast, matrix proteins in osteoid are subject to loss after decalcification because they may be bound to scattered apatite crystals, not to each other.

Animals↗

Measurement of bone morphogenetic proteins and other growth factors in demineralized bone matrix.

Osteoinductivity of demineralized bone matrix has been attributed to bone morphogenetic proteins (BMP). Other growth factors, including insulin-like growth factor-1 (IGF-1) and transforming growth factor-beta1 (TGF-beta1), have also been detected in demineralized bone matrix. Success of bone graft substitutes containing demineralized bone matrix has been assumed to be closely associated with osteoinductivity of the demineralized bone matrix. Because of differences in bone characteristics between donors and tissue banks, confirmation and measurement of osteoinductivity may play a crucial role in predicting the success of the bone graft substitute. In the current studies, BMP-2, BMP-4, TGF-beta1, and IGF-1 were measured in demineralized bone matrix. A strong association was noted between BMP-2 and TGF-beta1 levels. A strong association was also found between BMP-2 and new bone formation in an ectopic nude rat model.

Bone Demineralization Technique↗

Experimental study on allogenic decalcified bone matrix as carrier for bone tissue engineering.

The biocompatibility and osteogenic activity of allogenic decalcified bone matrix (DBM) used as a carrier for bone tissue engineering were studied. Following the method described by Urist, allogenic DBM was made. In vitro, DBM and bone marrow stromal cell (BMSC) from rabbits were co-cultured for 3-7 days and subjected to HE staining, and a series of histomorphological observations were performed under phase-contrast microscopy and scanning electron microscopy (SEM). In vivo the mixture of DBM/BMSC co-cultured for 3 days was planted into one side of muscules sacrospinalis of rabbits, and the DBM without BMSC was planted into other side as control. Specimens were collected at postoperative week 1, 2 and 4, and subjected to HE staining, and observed under SEM. The results showed during culture in vitro, the BMSCs adherent to the wall of DBM grew, proliferated and had secretive activity. The in vivo experiment revealed that BMSCs and undifferentiated mesenchymal cells in the perivascular region invaded gradually and proliferated together in DBM/BMSC group, and colony-forming units of chondrocytes were found. Osteoblasts, trabecular bone and medullary cavity appeared. The inflammatory reaction around muscles almost disappeared at the second weeks. In pure DBM group, the similar changes appeared from the surface of the DBM to center, and the volume of total regenerate bones was less than the DBM/BMSC group at the same time. The results indicated that the mixture of DBM and BMSC had good biocompatibility and ectopic induced osteogenic activity.

Animals↗

Instrumented posterolateral lumbar fusion using coralline hydroxyapatite with or without demineralized bone matrix, as an adjunct to autologous bone.

BACKGROUND CONTEXT: Autogenous posterolateral fusion with and without instrumentation has been reported with good results. However, difficult-to-fuse patients, such as smokers, elderly patients with poor bone quality and/or quantity, or patients with prior posterior surgeries, may have somewhat lower fusion rates. PURPOSE: To determine the efficacy of coralline hydroxyapatite with or without demineralized bone matrix as a bone graft extender in a human clinical model with long-term follow-up. STUDY DESIGN/SETTING: A retrospective series of 40 patients undergoing instrumented autogenous posterolateral lumbar fusion augmented with coralline hydroxyapatite with or without demineralized bone matrix. PATIENT SAMPLE: Long-term clinical and radiographic follow-up were examined for 40 patients who underwent an instrumented posterolateral fusion only. Patients undergoing anterior lumbar interbody fusion (ALIF) procedures were not considered part of the sample. METHODS: All patients underwent successful transpedicular fixation with autogenous posterolateral lumbar fusion. Fifteen cc of Pro Osteon 500 coralline hydroxyapatite (Interpore Cross International, Irvine, CA) was used at each level. An additional 10 cc of Grafton demineralized bone matrix gel (Osteotech, Eatontown, NJ) was used in 70% of these patients. RESULTS: An overall fusion rate of 92.5% was achieved. Pain and function improvement were good but somewhat age dependent and correlated with the number of comorbidities. Patients with Grafton DBM gel had a lower fusion rate of 89.3%. CONCLUSIONS: Based on this small retrospective review, coralline hydroxyapatite is an effective bone graft extender in difficult-to-fuse patients as an adjunct to autologous bone for posterolateral fusion of the lumbar spine when combined with rigid instrumentation.

Adult↗

Bone matrix therapy for aneurysmal bone cysts.

Aneurysmal bone cysts are unique pathologic entities that cause pain and local osseous destruction. Many surgical treatment modalities have been described. This article reports on the case of a 16-year-old high school athlete with left heel pain due to an aneurysmal bone cyst in the calcaneus. Curettage of the bone cyst was performed, and the void was filled with a commercially available mixture of cancellous bone and demineralized bone matrix. Early return to athletic activity was achieved, with no recurrence noted at 3-year follow-up.

Adolescent↗

Commercially available demineralized bone matrix compositions to regenerate calvarial critical-sized bone defects.

BACKGROUND: Demineralized bone matrix products are often used by surgeons to regenerate bone. Several different types of carriers have been combined with demineralized bone matrix to improve clinical handling and surgical outcome. The aim of the study was to quantitate bone regeneration in standard-sized calvarial defects (a critical-sized defect) in response to commercially available demineralized bone matrix formulations. METHODS: The commercial demineralized bone matrix formulations were tested as received in 8-mm-diameter calvarial critical-sized defects in an athymic rat model. The demineralized bone matrix treatment groups included the following: (1) Allomatrix; (2) demineralized bone matrix plus sodium hyaluronate (DBX); (3) DBX with poly(DL-lactide) mesh; 4) Dynagraft; (5) Grafton; (6) Regenafil; and (7) human demineralized bone matrix without a carrier. An eighth treatment was a poly(DL-lactide) mesh. At designated times of 2, 4, and 8 weeks, the critical-sized defects were recovered and processed for undecalcified histology and histomorphometry. Histomorphometric data were subjected to an analysis of variance and Fisher's protected least significant difference multiple comparison test. Significance was established at p <or= 0.05. RESULTS: Allomatrix, Dynagraft, Regenafil, and poly(DL-lactide) mesh alone had less bone formation than DBX, Grafton, DBX plus mesh, and demineralized bone matrix. CONCLUSIONS: DBX, DBX plus mesh, demineralized bone matrix, and Grafton produced more bone formation than Allomatrix, Dynagraft, mesh alone, and Regenafil.

Animals↗

Comparison of bone healing by demineralized bone matrix and autogenous cancellous bone in horses.

OBJECTIVE: The purpose of this study was to compare bone healing induced by equine demineralized bone matrix (DBM) to autogenous cancellous bone graft (ACB) or no graft (control) in a rib-defect model in horses. STUDY DESIGN: The osteogenic properties of ACB and DBM were evaluated in bilateral 19-mm circular defects created in the outer cortex of the 6th and 8th ribs of each horse. ANIMALS OR SAMPLE POPULATION: Eight mature horses. METHODS: Three rib defects in each horse were randomly treated with each of the 3 treatment groups, and the fourth rib defect received a random treatment. Rib sections, including the defects, were harvested 56 days after implantation and examined for bone mineral density, percent ash and calcium and graded for signs of radiographic and histological healing. RESULTS: All ribs were fractured at the defect site and were classified as nonunion fractures 56 days after implantation. There were no significant differences among groups in bone mineral density and signs of radiographic or histological healing. There was an increased volume of bone in control and ACB-treated sites compared with DBM-treated sites. Rib defects treated with ACB were significantly higher in percent ash and calcium than those treated with DBM. DBM elicited no inflammatory reaction, and remodeling occurred around the periphery and within vascular channels of the decalcified particles. CONCLUSION: DBM particles remodel from the periphery, which may explain the significantly lower percent ash, calcium, and bone when compared with ACB, because 2- to 4-microL pieces of DBM may act as space-occupying masses until completely mineralized. There was no evidence of enhanced healing associated with the use of DBM in this model. CLINICAL RELEVANCE: Particles of 2 to 4 mm DBM should not be used as an aid to fracture repair because particles of this size interfere with normal mineralization. However, our model of nonunion fracture healing may be useful in future studies.

Animals↗

Localization of 99mTc-diphosphonates in newly formed bone matrix as a measure of bone lesion detectability.

The lesion-to-normal-bone ratios of DBA-MDP (dibutylamino-methylene-diphosphonate), DPD (dicarboxypropane-diphosphonate) and MDP (methylene-diphosphonate) each labeled with 99mTc, were evaluated in experimental bone lesions. In 3-day old lesions this ratio was increased twofold for DBA-MDP in comparison with MDP and DPD which showed nearly equal ratios. Later on these differences became negligibly small. It is concluded that 99mTc-DBA-MDP is fixed more strongly in the immature bone matrix and that this will lead to an improvement in the detectability of lesions containing larger amounts of immature bone matrix.

Animals↗

The in vitro chondrogenic response of limb-bud mesenchyme to a water-soluble fraction prepared from demineralized bone matrix.

Demineralized adult bone matrix initiates de novo ectopic endochondral ossification 2-3 weeks following its intramuscular implantation into adult animals. This phenomenon appears to be similar, in some ways, to inductive cell-matrix interactions which regulate cartilage and bone formation during development. In the present study, we used embryonic chick limb-bud mesenchymal-cell cultures to bioassay extracts of demineralized bone matrix for chondrogenic activity. Guanidinium-chloride (4 M) extracts of demineralized bovine bone were dialyzed against buffers of decreasing ionic strength and then cold water. The cold-water-soluble fraction was found to stimulate chondrogenesis in intermediate-density limb-bud cell cultures (2.2 X 10(6) cells per 35-mm dish), as revealed by visual inspection with phase optics, toluidine-blue staining of fixed plates, and [35S] sulfate incorporation in the cell layer. Further fractionation of this material by anion-exchange, carbohydrate-affinity, and molecular-sieve chromotography produced a semipurified preparation possessing chondrogenic-stimulating activity at doses ranging from 3 to 10 micrograms/ml. The in vitro chondrogenic response of limb-bud mesenchymal cells was dose-dependent, required a minimal initial plating density of 2.08 X 10(5) cells/mm2 of culture dish, and developed gradually over 8-10 days. At an optimal dose of extract, a continuous exposure period of at least 2-3 days was necessary to produce detectable chondrogenic stimulation. In addition, the amount of cartilage formed following an 8-day exposure was markedly influenced by the culture 'age' of the mesenchymal cells (i.e., the time between plating and the start of treatment).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Decreased osteoinductive potential of bone matrix from ovariectomized rats.

The effect of estrogen deficiency on matrix-induced bone formation was investigated. Female rats were ovariectomized and given demineralized bone matrix (DBM) intramuscularly 3 weeks before termination. The DBM was taken from previously ovariectomized and from sham-operated on rats. The animals were killed at various times after ovariectomy (6-27 weeks). Implants were processed undemineralized for histologic and biochemical studies. Normal DBM implanted in ovariectomized or normal rats induced extensive bone formation 6 weeks postovariectomy. The amount of newly formed bone decreased with the age of host rats. Bone matrix taken from ovariectomized rats was incompletely resorbed in both ovariectomized and normal hosts, therefore reducing the extent of osteogenesis and bone-marrow formation. Instead, chondrogenesis was intensive, but delayed. The calcium, magnesium, and zinc contents were decreased in implants taken from ovariectomized rats when compared with implants taken from normal animals. Normal osteoinduction with DBM taken from normal rats and implanted in ovariectomized rats and the absence of osteogenesis with DBM taken from ovariectomized rats indicate that an estrogen-deficient environment is not crucial for altered matrix-induced endochondral bone formation in ovariectomized rats. An altered composition of matrix from ovariectomized rats and a subsequent abnormality in the cell-matrix interaction should be considered responsible.

Animals↗

BAPN dose dependence of mature crosslinking in bone matrix collagen of rabbit compact bone: corresponding variation of sonic velocity and equatorial diffraction spacing.

Crosslinking density in demineralized bone matrix collagen was found to depend on the beta-aminopropionitrile (BAPN) dose level for compact bone from rabbit femurs. The dependence was demonstrated for the hydroxypyridinium (HP) concentration, a mature crosslink. A more consistent dependence on BAPN dosage was observed for the fraction of the demineralized bone matrix insoluble in 0.5 M acetic acid (AIF) corresponding to the remaining crosslinked collagen. The average HP concentration in 21 week old controls was 0.24 moles HP/mole collagen which decreased to 0.13 +/- 0.04 for the same age rabbits dosed with 1 gm BAPN/kg/day for 13 wks. The comparable mean AIF values were 0.91 for controls and 0.75 for maximum dose level. Most of the effect of BAPN on crosslinking was observed at the lower dosages below 0.2 g/kg/day. On the other hand, overt osteolathyritic symptoms are seen only for BAPN dosages greater than 0.2 g/kg/day. The mean sonic plesio-velocity was previously found to decrease from 3.4 to 3.03 km/sec as the BAPN dosage was increased. A similar close relationship was discovered for the equatorial diffraction spacing in fully mineralized bone which increased from 1.235 for normal rabbit bone to 1.28 nm for maximum dose. Most of the effect on these physical properties is exhibited at the highest BAPN dosage after much of the decrease in mature crosslinking density has been observed and when the further decrease in mature crosslinking density proceeds very slowly with increased drug dosage. These observations suggest that osteolathyrism does not become manifest until practically all mature crosslinking that can be affected has been inhibited. The mineralization process apparently can be maintained in the newly laid collagen even in the presence of severe osteolathyritic conditions. Intermolecular crosslinking in bone collagen appears to play an important role in the development of bone properties whether by direct or indirect processes. Much of the effects on bone properties occur at the higher BAPN dosages where overt osteolathyrism is observed and where there seem to be only small changes in crosslinking density.

Acetates↗