Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “BONE REGENERATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources
PubMed2004

Recruitment of mesenchymal stem cells and expression of TGF-beta 1 and VEGF in the early stage of shock wave-promoted bone regeneration of segmental defect in rats.

Extracorporeal shock wave (ESW) treatment has recently been established as a method to enhance bone repair. Here, we reported that ESW-promoted healing of segmental defect via stimulation of mesenchymal stem cell recruitment and differentiation into bone forming cells. Rats with a segmental femoral defect were exposed to a single ESW treatment (0.16 mJ/mm(2), 1 Hz, 500 impulses). Cell morphology and histological changes in the defect region were assessed 3, 7, 14, and 28 days post-treatment. Presence of mesenchymal stem cell was assayed by immuno-staining for RP59, a recently discovered marker, and also production of TGF-beta 1 and VEGF was monitored. ESW treatment increased total cell density and the proportion of RP59 positive cells in the defect region. High numbers of round- and cuboidal-shaped cells strongly expressing RP59 were initially found. Later, the predominant cell type was spindle-shaped fibroblastic cells, subsequently, aggregates of osteogenic and chondrogenic cells were observed. Histological observation suggested that bone marrow stem cells were progressively differentiated into osteoblasts and chondrocytes. RP59 staining was initially intense and decreased with the appearance of expression depended on the differentiation states of osteogenic and chondrogenic cells during the regeneration phase. Mature chondrocytes and osteoblasts exhibited only slight RP59 immuno-reactivity. Expression of TGF-beta 1 and VEGF-A mRNA in the defect tissues was also significantly increased (P<0.05) after ESW treatment as determined by RT-PCR. Intensive TGF-beta 1 immuno-reactivity was induced immediately, whereas a lag period was observed for VEGF-A. Chondrocytes and osteoblasts at the junction of ossified cartilage clearly exhibited VEGF-A expression. Our findings suggest that recruitment of meseoblasts at the junction of ossified cartilage clearly exhibited mesenchymal stem cells is a critical step in bone reparation that is enhanced by ESW treatment. TGF-beta 1 and VEGF-A are proposed to play a chemotactic and mitogenic role in recruitment and differentiation of mesenchymal stem cells.

Animals↗
PubMed1993

Membrane exposure during bone regeneration before implant placement: management and results. A report of two cases.

Two patients with apical lesions on maxillary central incisors showed large osseous defects of the residual ridge. E-PTFE membranes were used for ridge reconstruction, which allowed for the placement of implants of appropriate diameters. In the two cases described, the membranes were exposed and replaced. This technique facilitated atrophic ridge reconstruction in spite of premature membrane exposure.

Adult↗
PubMed1999

Distraction osteogenesis to achieve mandibular vertical bone regeneration: a case report.

In this case report a surgical technique for vertical ridge augmentation is presented. The procedure, performed in a 30-year-old woman with an atrophied alveolar ridge in the anterior portion of the mandible, is based on the biologic concept of osteogenesis distraction previously introduced in orthopedic and maxillofacial surgery. After elevation of a full-thickness flap a horizontal osteotomy was performed 7 to 8 mm from the top of the ridge. Two vertical osteotomies were prepared with drills of increasing diameter (2, 2.8, and 3.25 mm), tapping was performed for the first 5 to 6 mm, and two distractor base plugs were placed at the base of the osteotomies with a repositioning tool. An intraosseous distraction implant was then inserted and 2 inward vertical cuts were made in the bone to allow proper distraction to take place. Correct functioning of the device was checked by distracting the bone fragment 1 mm using the axial distraction screw. A latency distraction healing screw was inserted in each of the distraction implants and the area was left to heal for 5 days. Once primary healing had occurred, the distraction of the newly formed bone callus was activated each day for 10 days (1 mm per day). At the end of the distraction period a final distraction screw was left in place and a final healing screw was inserted. During this time there were no complications and the patient on no occasion complained of discomfort. The distractor device was removed 30 days later, leaving the base plugs in place. One month later a vertical augmentation of 7 mm had been achieved; the base plugs were removed, 3 intraosseous implants were inserted, and a biopsy of the newly formed tissue was obtained. Histologic evaluation of the biopsy specimen showed woven bone formation approximately 75 days after the initial procedure.

Adult↗
PubMed1996

Radiographic evaluation of bone regeneration following periodontal surgery with or without expanded polytetrafluoroethylene barriers.

In 16 patients with advanced periodontitis, 23 teeth exhibiting interproximal intrabony defects were treated by conventional periodontal surgery (n = 10, control) or guided tissue regeneration (GTR) technique using expanded polytetrafluoroethylene (ePTFE) barriers (n = 13, test), respectively. Clinical parameters were assessed before and 6 months after surgery. Presurgically and 3 and 6 months postsurgically standardized bite-wing radiographs were taken. Using a loupe and a computer-assisted system, respectively, the distances from the cemento-enamel junction (CEJ) to alveolar crest (AC) and CEJ to the most apical extension of bony defect (BD) were measured. The average gain of attachment was assessed 2.33 mm in the control group and 3.17 mm in the test group. The bony fill was measured 0.97 mm and 0.97 mm in the control group and 0.93 mm and 1.68 mm in the test group after 3 and 6 months, respectively, using a loupe. Using a computer-assisted system 0.83 mm and 1.82 mm of bone fill could be measured (control) and 0.76 mm and 1.79 mm (test) after 3 and 6 months, respectively. Compared to the gold standard of surgical measurements, the computer-assisted analysis of radiographs underestimated bone loss significantly less than evaluation with a loupe (P < 0.002). Compared to conventional periodontal surgery, the GTR technique resulted in higher attachment gain and bony fill. However, the high variation of surgical results in the test group prevented the calculation of a statistically significant difference.

Adult↗
PubMed2006

Bone regeneration on computer-designed nano-fibrous scaffolds.

The ability to control architectural features in tissue engineering scaffolds is critical to the success of neo-tissue regeneration. In this work, reverse solid freeform fabrication and thermal phase separation of poly(L-lactic acid) (PLLA) solutions were used to create three-dimensional nano-fibrous (NF) scaffolds with complex geometries on the macro- and micro-scales. This approach allows for the fabrication of NF matrices while having precise control of internal pore size and structure, as well as external scaffold shape including architectures generated from computed-tomography scans and histological sections. In vitro cell cultivation experiments with MC3T3-E1 pre-osteoblasts were performed on NF scaffolds and on similarly designed solid-walled (SW) scaffolds that did not have nano-fibers. Proliferation studies showed significantly more cells on NF scaffolds after 7 d. In differentiation studies, the NF scaffolds displayed more uniform matrix and mineral production throughout. Real-time PCR also showed significantly higher expression of osteocalcin and bone sialoprotein mRNAs after 2 and 6 weeks in the NF scaffolds. Expression of type I collagen mRNA was lower in NF scaffolds which possibly indicates quicker differentiation on the NF substrate. In summary, we controlled the geometry of NF PLLA scaffolds at multiple size scales, and the in vitro results showed that these NF scaffolds were advantageous to control scaffolds for bone tissue engineering.

3T3 Cells↗
PubMed2004

Current strategies for cell delivery in cartilage and bone regeneration.

Several cell-based tissue-engineering therapies are emerging to regenerate damaged tissues. These strategies use autologous cells in combination with bioresorbable delivery materials. Major functions of a delivery scaffold are to provide initial mechanical stability, homogenous three-dimensional cell distribution, improved tissue differentiation, suitable handling and properties for delivery and fixation into patients. Delivery of cells can be achieved using injectable matrices, soft scaffolds, membranes, solid load-bearing scaffolds or immunoprotective macroencapsulation. Thus, to expand the clinical potential, next generation therapies will depend on smart delivery concepts that make use of the regenerative potential of stem cells, morphogenetic growth factors and biomimetic materials.

Animals↗
PubMed2006

[Use of native and cross-linked collagen membranes for guided tissue and bone regeneration].

A material which is used as a barrier for GBR/GTR procedures has to satisfy several physicochemical characteristics such as biocompatibility, tissue integration, barrier function, and dimensional stability. Recently, many investigations reported on the use of products derived from type I and type III porcine or bovine collagen. Collagen membranes are predominantly resorbed by enzymatic activity (protease and collagenase). To decrease resorption, various physical and chemical cross-linking techniques have been used. Although nowadays cross-linking of collagen seems to be a commonly used procedure, its impact on physicochemical properties of the membrane is still unknown. The aim of the present literature review is to evaluate the potential use of different collagen membranes for GBR/GTR procedures.

Absorbable Implants↗
PubMed1996

Histological evaluation of freeze-dried dura mater (FDDMA) used in guided bone regeneration (GBR): a time course study in man.

In 26 patients freeze-dried dura mater (FDDMA) membranes were used in fenestrations and dehiscences around dental implants, in implants inserted into postextraction sockets, in vertical ridge augmentation and in sinus lifting procedures. A re-entry procedure was carried out after 6, 9 and 12 months. In all patients a small portion of the membrane was removed and examined. No inflammatory infiltrate was present in the tissues around the membranes. No cells were present inside the membranes and only in the most peripheral portions was it possible to observe a few cells positive to acid phosphatase. The FDDMA membranes appeared to resorb slowly, did not seem to elicit an inflammatory reaction, and at 12 months they still appeared to play a role in cell occlusion.

Adult↗
PubMed2004

Influence of beta-radiation sterilisation in properties of new chitosan/soybean protein isolate membranes for guided bone regeneration.

Novel chitosan (cts) and soybean protein isolate (SI) blended membranes were prepared. These membranes were produced by solvent casting. Besides combining the advantages of both materials, cts/SI membranes exhibit a biphasic structure that will eventually originate in situ porous formation, through a two-step degradation mechanism. In this particular work the effect of beta-radiation over the properties of these membranes was evaluated. beta-radiation sterilisation was performed at three different doses (25, 50 and 100 kGy) and eventual surface chemical changes were evaluated by Fourier transformed infrared--with attenuated total reflection and contact angle measurements. Moreover, eventual bulk properties changes due to beta-radiation were assessed by means of mechanical tensile tests and water uptake measurements. In general, no substantial changes were detected on the studied properties, with the exception of the surface energy that was found to be slightly increased for higher applied doses.

Beta Particles↗
PubMed2006

Poly-epsilon-caprolactone/hydroxyapatite composites for bone regeneration: in vitro characterization and human osteoblast response.

Polycaprolactone (PCL), a semicrystalline linear resorbable aliphatic polyester, is a good candidate as a scaffold for bone tissue engineering, due to its biocompatibility and biodegradability. However, the poor mechanical properties of PCL impair its use as scaffold for hard tissue regeneration, unless mechanical reinforcement is provided. To enhance mechanical properties and promote osteoconductivity, hydroxyapatite (HA) particles were added to the PCL matrix: three PCL-based composites with different volume ratio of HA (13%, 20%, and 32%) were studied. Mechanical properties and structure were analysed, along with biocompatibility and osteoconductivity. The addition of HA particles (in particular in the range of 20% and 32%) led to a significant improvement in mechanical performance (e.g., elastic modulus) of scaffold. Saos-2 cells and osteoblasts from human trabecular bone (hOB) retrieved during total hip replacement surgery were seeded onto 3D PCL samples for 1-4 weeks. Following the assessment of cell viability, proliferation, morphology, and ALP release, HA-loaded PCL was found to improve osteoconduction compared to the PCL alone. The results indicated that PCL represents a potential candidate as an efficient substrate for bone substitution through an accurate balance between structural/ mechanical properties of polymer and biological activities.

Alkaline Phosphatase↗
PubMed1985

[Histogenesis of skeletogenic tissue in bone regeneration during distraction].

Light and electron microscopy were employed to study the histogenesis of the skeletogenous tissue during stable distraction osteosynthesis according to G. A. Ilizarov. Osteosynthesis proceeded on the basis of the invariably existing fibrillar connective tissue growth plate situated in the medium part of the distraction regenerate. Osteogenesis was continuously accompanied by angiogenesis. Preservation of the connective tissue plate is accounted for by the stimulating influence of distraction on fibrillogenesis. The authors suggest the common character of the histogenesis of the vascular and bone tissues in the connective tissue blastema of the interfragmental distraction regenerate.

Animals↗
PubMed2005

Patterns and localization of gene expression during intramembranous bone regeneration in the rat femoral marrow ablation model.

Tissue formation and repair are dependent upon cascades of biological events, but the signals involved and the possible gene coexpression patterns during intramembranous bone repair are only poorly understood. We sought to place this mode of regeneration in context by profiling quantitative gene expression for a panel of 39 genes between days 1 and 14 following rat femoral marrow ablation. In situ hybridization was employed to localize a subset of genes. Additionally, principal components analysis was conducted to identify underlying factors suggestive of coexpression patterns. During inflammation (days 1-5), several genes, including cyclooxygenase-1 and -2, showed downregulation. Other proinflammatory cytokines, tumor necrosis factor-alpha and interleukin-1beta, exhibited increasing levels around day 5. During repair (days 3-10), growth factors, receptors, and inhibitor genes for transforming growth factor- beta; basic fibroblast growth factor; bone morphogenetic proteins 2, 4, and 7; vascular endothelial growth factor; and insulin-like growth factor-I were upregulated. In addition, the gene for core binding factor-alpha1 and markers of osteoblast function such as alkaline phosphatase, collagen type I, osteonectin, osteopontin, and osteocalcin had peak expression at day 5 or 7. The remodeling phase (days 10-14) was characterized by peaks for cytokines associated with osteoclastic activity including receptor activator of nuclear factor-kappaB, receptor activator of nuclear factor-kappaB ligand (RANKL), cathepsin K, tumor necrosis factor-alpha, interleukin-6, and cyclooxygenase-2. In situ hybridization showed that the most common sites of increased signal were within osteoblastic cells on trabecular and endosteal surfaces. Principal components analysis identified eight underlying factors that together explained over 80% of the variance in the data.

Animals↗
PubMed2000

Tissue regeneration in bone defects adjacent to endosseous implants: an experimental pilot study.

Extraction socket defects or alveolar ridge defects may limit or restrict placement of implants. The present study assessed the efficacy of inducing bone formation with demineralized freeze-dried bone (DFDB), osteoinduction with hydroxyapatite (HA), and guided bone regeneration with expanded polytetrafluoroethylene (e-PTFE) in bone defects adjacent to endosseous implants in an animal model. Twenty-four implants were placed in the long bones of 3 pigs. After preparation of 24 cylindric acute defects adjacent to the coronal 5 mm of each implant, 18 of the defects were treated by DFDB, HA, or e-PTFE. The 6 remaining defects healed spontaneously with no treatment (controls). In each pig, one tibia received 4 commercially pure titanium screw implants (3.75 mm x 15 mm), while the contralateral tibia received 4 HA-coated cylindric implants (3.25 mm x 15 mm). Bone formation in response to the 3 treatments and control cases was evaluated using computer-assisted densitometric image analysis. The results showed that a higher density of tissue formed under e-PTFE membranes. A significantly greater increase in bone density was noticed in bone defects treated with an e-PTFE membrane vs DFDB (P = 0.04), in e-PTFE vs control sites (P = 0.04), and in defects treated with HA vs DFDB (P = 0.04) in HA-coated implants. In titanium implants the differences observed were not significant. It was also observed that bone regeneration in defects treated with HA differs with the type of implant used (titanium vs HA-coated implants), but such differences were not significant.

Analysis of Variance↗
PubMedDate not supplied

[Formation of an organic matrix in the traction method of bone regeneration and characteristics of its mineralization in experimental tibia lengthening].

Stretching of dog crus was carried out using transbone distractional osteosynthesis method by Ilizarov. Distribution of calcium, phosphorus and organic substances in zones of regenerating tissue was studied within 1 and 2 months after stretching and within 2 months after the subsequent fixation of the leg in the apparatus. Zones of non-mineralized osteoids were not found already during destruction. In the zones content of minerals varied only slightly and the less mineralized middle zone contained about 66% of calcium and phosphorus as compared with their level in mature compact bone tissue. Crystals of hydroxyapatite were found in zones close to bone fragments using electron microscopy. The data obtained suggest that under optimal conditions of regeneration provided by the method the newly formed bone matrix is partially mineralized during its synthesis. Reverse correlation was detected between contents of minerals and glycosaminoglycans. Middle zones with a slightly higher concentration of glycosaminoglycans were less mineralized. Within 2 months after stopping of distraction differences between zones were decreased, content of glycosaminoglycans was lowered as minerals accumulated; content of minerals became higher than in spongy bone tissue but slightly lower as compared with compact bone.

Animals↗
PubMed1988

Regenerating bone marrow produces a potent growth-promoting activity to osteogenic cells.

It is well documented that injury to bone marrow is followed by an osteogenic phase that precedes the complete tissue regeneration. We have recently shown that postablation healing of bone marrow in rat tibiae is associated with a systemic increase in osteogenesis. It was hypothesized that a growth factor(s) with an effect on osteogenic cells is produced in the healing limb, is transferred to the blood circulation, and enhances osteogenesis systemically. To test growth factor production, healing bone marrow-conditioned medium was prepared with tissue separated from rat tibias during the osteogenic phase and assayed for enhancement of mitogenic activity in culture of osteogenic rat osteosarcoma cells (ROS 17/2). Partial purification of healing bone marrow-conditioned medium-derived growth factor(s) consisted of gel filtration on Sephadex G-25, boiling, chromatography on heparin-Sepharose, and gel filtration on Sephadex G-75. Mitogenic activity eluted in the void volume of the Sephadex G-25 column (mol wt greater than 5,000). Potent activity resolved from heparin-Sepharose with PBS, and on filtration by Sephadex G-75 this activity recovered in 3 peaks with mol wt estimates of 35,000, 19,000, and less than 10,000. The partially purified factor also showed considerable stimulatory effect on DNA synthesis in osteoblastic fetal rat calvarial cells and on in vitro elongation of fetal long bone; it had only a small effect on nonosteoblastic ROS and fetal rat calvarial cells. These data indicate that healing bone marrow produces growth factor activity with a preferential effect on osteogenic cells. It is suggested that local growth factors have a role as mediators in the sequence of events whereby bone marrow expresses its osteogenic potential. During postablation healing of bone marrow these factors may also function as systemic promoters to osteogenic cells.

Animals↗
PubMed1992

Biodegradable guide for bone regeneration. Polyurethane membranes tested in rabbit radius defects.

Segmental, 1-cm osteoperiosteal defects were produced in both radii of 10 rabbits. One defect was covered with a biodegradable polyurethane membrane formed as a tube. The contralateral defect served as an untreated control. Healing was analyzed by radiographic and histologic studies after 5 weeks. Nine out of 10 control defects displayed nonunion, whereas membrane-treated defects consistently healed by forming callus external to the membrane fusing the bone fragments. Loose connective tissue was predominant in the bone gap underneath the membrane. Presumably, the membrane has served as a scaffold for regenerating periosteum.

Animals↗
PubMed1997

Periodontal and peri-implant bone regeneration: clinical and histologic observations.

The principle of guided tissue regeneration by barrier membranes to restore lost periodontal tissue around natural teeth has also been used around osseointegrated implants in an attempt to restore alveolar ridge defects. While most periodontal procedures in the literature describe root coverage by mucogingival surgery, which achieves healing through soft tissue attachment, regeneration of denuded root surfaces is performed by guided tissue regeneration using expanded polytetrafluoroethylene barrier membranes and demineralized freeze-dried bone allografts as inductive/conductive materials. In this study the technique is applied in two partially exposed cylindrical hydroxyapatite-coated implants in extraction sites in one patient. Surgical reentry in both sites is presented, with histologic examination revealing new bone formation on the exposed root surface and the hydroxyapatite-coated implants.

Alveolar Bone Loss↗