133 research outputs found
DS_10.1177_0363546518818792 – Supplemental material for Osteointegration of a Novel Silk Fiber–Based ACL Scaffold by Formation of a Ligament-Bone Interface
No full textSupplemental material, DS_10.1177_0363546518818792 for Osteointegration of a Novel Silk Fiber–Based ACL Scaffold by Formation of a Ligament-Bone Interface by Andreas Herbert Teuschl, Stefan Tangl, Patrick Heimel, Uwe Yacine Schwarze, Xavier Monforte, Heinz Redl and Thomas Nau in The American Journal of Sports Medicine</p
Impact of DBBM Fragments on the Porosity of the Calvarial Bone: A Pilot Study on Mice.
No full textDeproteinized bovine bone mineral (DBBM) is brittle and can break into fragments. Here, we examined whether DBBM fragments have an impact on mice calvarial bone during bone augmentation. DBBM was either randomly crushed (DBBM fragments) or left undisturbed (DBBM granules). Then, DBBM fragments or original DBBM granules were placed onto calvarial bone in 20 BALB/c mice. Following random allocation, ten mice received DBBM fragments and ten mice received original DBBM granules. After fourteen days of healing, micro computed tomography (micro-CT) and histological analysis of the augmented sites were performed. The primary outcome was the porosity of the calvarial bone. The micro-CT analysis revealed that DBBM fragments failed to significantly change the porosity of the calvarial bone as compared with original DBBM granules, despite the slightly higher bone resorption in the DBBM fragment group, 10.3% (CI 6.3-11.6) versus 6.1% (CI 4.1-7.8, p = 0.355), respectively. The cortical bone volume was not altered by DBBM fragments as compared with original DBBM granules, i.e., 79.0% (CI 78.9-81.2) versus 81.5% (CI 80.1-83.3, p = 0.357), respectively. The DBBM fragment group revealed similar bone thickness values as compared with the DBBM granules group, i.e., 0.26 mm (CI 0.23-0.29) versus 0.25 mm (CI 0.22-0.27, p = 0.641), respectively. The histological evaluation supported the micro-CT observations, displaying minor signs of porosity and resorption. The particle-size distribution analysis confirmed a shift towards smaller particle sizes in the DBBM fragment group. These findings suggest that DBBM fragments behave similarly to original DBBM granules in terms of bone morphological changes at augmented sites
Bone-Conditioned Medium Obtained From Calvaria, Mandible, and Tibia Cause an Equivalent TGF-β1 Response In Vitro.
No full textBones with different embryological origin and mode of ossification are supposed to vary in their capacity for supporting graft consolidation. The aim of the current pilot study was to assess the TGF-β1 activity of bone chips obtained from distinct anatomic locations. Conditioned medium was prepared from bone chips harvested from pig calvaria, mandible, and tibia. Human oral fibroblasts were exposed to bone-conditioned medium (BCM) followed by reverse transcriptase polymerase chain reaction of the TGF-β1 target genes. Also an immunoassay for interleukin 11 (IL-11) and TGF-β1 was performed. The impact of BCM on alkaline phosphatase activity was determined with murine MC3T3-E1 osteogenic cells. The authors report here that BCM contains TGF-β1 in the ng/mL range. Bone chips prepared from pig calvaria, mandible, and tibia femur had a similar capacity for increasing the expression of the TGF-β1 target genes IL-11, NOX4, and PRG4. Correspondingly, immunoassays revealed similar production of IL-11 by human oral fibroblasts. Furthermore, conditioned medium obtained from the 3 bones decreased alkaline phosphatase activity in MC3T3-E1 osteogenic cells. These preliminary data demonstrate that particulated bone grafts, regardless of embryological origin, mode of ossification and morphology, release a similar TGF-β1 activity
Kontrastverstärktes μCT von peripheren Nerven und Rückenmark
No full textSpinal cord and peripheral nerve injury are a common result of traumatic injury. The treatment options are still limited and consequences of these injuries can be severe and may result in permanent disability and reduction in quality of life. There is an urgent need for research into new treatment options. Novel imaging modalities may provide new insights into the mechanisms of injury and regeneration. Contrast enhanced computed tomography (CECT) allows the visualization of soft tissues with the use of contrast agents. In this work, we sought to investigate the viability of CECT for use in the context of peripheral nerve and spinal cord injury repair. We investigated the staining mechanisms of Lugol’s iodine staining on rat limbs by comparing repeated staining’s at various concentrations. The knowledge gained was employed to stain a peripheral nerve injury which was regenerated using a silk based nerve guidance conduit. Lugol’s iodine was further used to stain rat spinal cords after impact injury. We further investigated the staining of healthy and injured spinal cords using Lugol’s iodine, Accupaque and hafnium-substituted Wells-Dawson polyoxometalate (Hf-POM). Accupaque was then employed as a contrast agent in a rat spinal cord injury experiment. We were able to optimize Lugol’s iodine staining for a peripheral nerve and spinal cord injury regeneration context. The staining was successfully employed in studies on peripheral nerve and spinal cord injuries in rats. In the peripheral nerve, the degree of bridging and blood supply through macroscopic holes in the nerve guidance conduit could be evaluated. In the spinal cord, the geometry of the cysts and remaining healthy tissue were quantified on the CECT scans. We were further able to demonstrate the use of CECT in both the healthy and injured spinal cord in high resolution scans. In the Accupaque stained spinal cords, both the cyst and damaged tissue volume could be quantified in great detail. The CECT techniques demonstrated in this work enable non-destructive visualization of the healthy and injured spinal cord as well as injured peripheral nerve at a high level of detail. This new tool may provide new insights into the anatomy and injury mechanics of the spinal cord and peripheral nerves.Verletzungen des Rückenmarks und peripherer Nerven sind häufige Folgen von Unfalltraumata. Die verfügbaren Behandlungsmöglichkeiten sind weiterhin begrenzt. Verletzungen können schwerwiegende Folgen haben und eine dauerhafte Behinderung und eine erhebliche Einschränkung der Lebensqualität nach sich ziehen. Es besteht ein dringender Bedarf an Forschung zu neuen Behandlungsoptionen. Neue Bildgebungsverfahren könnten neue Einblicke in die Mechanismen von Verletzungen und Regeneration ermöglichen. Die kontrastverstärkte Computertomographie (CECT) erlaubt durch den Einsatz von Kontrastmitteln die Visualisierung von Weichgeweben. In dieser Arbeit untersuchten wir die Eignung der CECT im Kontext der Reparatur von peripheren Nerven- und Rückenmarksverletzungen. Wir analysierten die Färbemechanismen von Lugol’scher Jodlösung an den Gliedmaßen von Ratten, indem wir wiederholte Färbungen mit unterschiedlichen Konzentrationen verglichen. Das gewonnene Wissen wurde verwendet, um verletzte periphere Nerven zu färben, die mit einer seidenbasierten Nervenleitungsprothese regeneriert wurde. Zusätzlich wurde Lugol’scher Jodlösung zur Färbung von Rattenrückenmark nach einer traumatischen Verletzung eingesetzt. Wir untersuchten weiterhin die Färbung von gesundem und verletztem Rückenmark mit Lugol’scher Jodlösung, Accupaque und Hafnium-substituiertes Wells-Dawson-Polyoxometallat (Hf-POM). Accupaque wurde anschließend als Kontrastmittel in einem Experiment bei Rückenmarksverletzung in Ratten eingesetzt. Es gelang uns, die Kontrastierung mit Lugol’scher Jodlösung für die Anwendung im Kontext der Regeneration von peripheren Nerven- und Rückenmarksverletzungen zu optimieren. Die Färbung wurde erfolgreich in Studien zu peripheren Nerven- und Rückenmarksverletzungen bei Ratten angewendet. Im Bereich der peripheren Nerven konnten der Grad der Überbrückung sowie die Blutversorgung durch makroskopische Öffnungen in der Nervenleitungsprothese evaluiert werden. Im Rückenmark wurden Geometrie der Zysten und verbleibendes gesundes Gewebe auf den CECT-Scans quantifiziert. Darüber hinaus konnten wir die Anwendung der CECT bei gesundem und verletztem Rückenmark in hochauflösenden Scans demonstrieren. Bei den mit Accupaque gefärbten Rückenmarkproben konnten sowohl das Zystenvolumen als auch das Volumen des geschädigten Gewebes detailliert quantifiziert werden. Die in dieser Arbeit demonstrierten CECT-Techniken ermöglichen eine zerstörungsfreie Visualisierung des gesunden und verletzten Rückenmarks sowie des verletzten peripheren Nervs mit einem hohen Detailgrad. Dieses neue Werkzeug ermöglicht neue Einblicke in die Anatomie und Verletzungsmechanismen des Rückenmarks und der peripheren Nerven
A quantification of regenerated bone tissue in human sinus biopsies: influences of anatomical region, age and sex
No full textObjectives: Sinus augmentation is a standard procedure to increase vertical bone supply for dental implants in the atrophic posterior maxilla. Despite the longstanding application of this method, information about some basic factors that could potentially influence bone regeneration after sinus augmentation is rare. The objective of this study was therefore to quantify the impact of the maxillary region (premolar/molar) and patients' age and sex on bone regeneration after sinus grafting. Material and methods:
Sinus augmentation procedures were performed in 107 patients (66 female: 52.8 ± 11.0 years, 41 male: 50.6 ± 11.3 years). After 6 ± 1 months, 201 sinus biopsies were harvested and histomorphometrically analysed. Height (oldHt) and bone volume fraction of pristine bone (oldBV/TV), as well as the amount of new bone (newBV/TV) and bone‐to‐bone substitute contact (BBSC) in the augmentation area, were assessed. Results: In women, newBV/TV in the augmented sinus decreased significantly by 0.22 ± 0.08% per year. In men, no similar trend was observed. There were strong influences of the maxillary region and the dimensions of the host bone. In the premolar region, newBV/TV was 23.1 ± 7.9% and 25.1 ± 10.1%; in the molar region, newBV/TV averaged 20.4 ± 9.4% and 17.8 ± 8.8% for women and men, respectively. The greater the thickness of the wall of the sinus floor (mainly in the former premolar region), the greater was the amount of new bone tissue formed in the spaces in‐between bone substitute particles. Conclusions: These empirical results derived from a large human sample, link factors that influence the quality of biomaterial integration to the known clinical risks for the success of dental implants.Karoline Maria Reich, Christian Domitian Huber, Patrick Heimel, Christian Ulm, Heinz Redl, Stefan Tang
Osteocyte lacunar density and area in newly formed bone of the augmented sinus
No full textOBJECTIVES
Osteocytes, the most common cells of the bone, are buried in lacunae. Density and area of the osteocyte lacunae change with increasing maturation of the newly formed bone. Evaluation of osteocyte lacunae can therefore provide insights into the process of graft consolidation.
MATERIALS AND METHODS
Here, we determined the osteocyte lacunar density (number of osteocyte lacunae per bone area; N.Ot/BAr) and the osteocyte lacunar area in μm(2) (Lac.Ar) in histological specimens 6 and 12 weeks after the sinuses of 10 minipigs were augmented with Bio-Oss(®) , a deproteinized bovine bone mineral, and Ostim(®) , an aqueous paste of synthetic nanoparticular hydroxyapatite. The region of interest was defined by the following criteria: (i) >1 mm from the host bone, (ii) >0.5 mm from the sinus mucosa, (iii) minimum area of 0.2 mm(2) , and (iv) bone tissue spanning at least two bone substitute particles.
RESULTS
The overall osteocyte lacunar density was significantly higher in the Bio-Oss(®) group than in the Ostim(®) group and decreased during the observation period at a similar range in both groups. The osteocyte lacunar area was smaller in the Bio-Oss(®) group than the Ostim(®) group but there was no significant change within the groups over time.
CONCLUSIONS
These results suggest that bone substitutes affect the osteocyte lacunar density and the osteocyte lacunar area in the newly formed bone within the augmented sinus in this particular model situation. These measures can provide insights into the maturation of newly formed bone in the augmented sinus
Active and Passive Mineralization of Bio-Gide® Membranes in Rat Calvaria Defects.
No full textBio-Gide® is a collagen membrane routinely used in guided bone regeneration. Recent studies have shown that this collagen membrane has osteoconductive properties, meaning that it can support the growth of new bone. However, it has also been observed that the collagen membrane has areas of mineralized fibers which can occur spontaneously and independently of osteoblasts. To better understand how this works, we established a model using minced collagen membranes to reduce the active mineralization of intact collagen membranes in favor of passive mineralization. We thus compared the original intact membrane with a minced collagen membrane in a 5 mm calvarial defect model in Sprague Dawley rats. After three weeks of healing, histology and microcomputed tomography (μCT) were performed. Histological analysis confirmed the osteoconductive properties, with new bone growing inside the intact collagen membrane. However, in minced collagen membranes, the osteoconductive properties were restricted to the defect margins. Interestingly, histology revealed large mineralized areas indicating passive mineralization with no signs of bone formation. In the μCT analysis, the intact collagen membranes caused a higher median mineralized volume (1.5 mm3) compared with the minced group (0.4 mm3), but this lacked significance (p = 0.09). The μCT analysis needs to be interpreted carefully, particularly in defects filled with minced membranes, considering that the mineralized tissue may not necessarily be bone but also the result of passive mineralization. Taken together, the findings suggest that Bio-Gide® collagen membranes support bone formation while also exhibiting potential for passive mineralization
Dental and periodontal phenotype in sclerostin knockout mice.
No full textSclerostin is a Wnt signalling antagonist that controls bone metabolism. Sclerostin is expressed by osteocytes and cementocytes; however, its role in the formation of dental structures remains unclear. Here, we analysed the mandibles of sclerostin knockout mice to determine the influence of sclerostin on dental structures and dimensions using histomorphometry and micro-computed tomography (μCT) imaging. μCT and histomorphometric analyses were performed on the first lower molar and its surrounding structures in mice lacking a functional sclerostin gene and in wild-type controls. μCT on six animals in each group revealed that the dimension of the basal bone as well as the coronal and apical part of alveolar part increased in the sclerostin knockout mice. No significant differences were observed for the tooth and pulp chamber volume. Descriptive histomorphometric analyses of four wild-type and three sclerostin knockout mice demonstrated an increased width of the cementum and a concomitant moderate decrease in the periodontal space width. Taken together, these results suggest that the lack of sclerostin mainly alters the bone and cementum phenotypes rather than producing abnormalities in tooth structures such as dentin
Impact of a Static Magnetic Field on Early Osseointegration: A Pilot Study in Canines
No full textA static magnetic field generated by neodymium–iron–boron (NdFeB) magnets placed in the inner cavity of dental implants can enhance bone regeneration in rabbits. It is, however, unknown whether static magnetic fields support osseointegration in a canine model. We therefore determined the potential osteogenic effect of implants carrying NdFeB magnets inserted in the tibia of six adult canines in the early stages of osseointegration. Here, we report that after 15 days of healing, magnetic and regular implants showed a high variation with a median new bone-to-implant contact (nBIC) in the cortical (41.3% and 7.3%) and the medullary (28.6% and 44.8%) region, respectively. Consistently, the median new bone volume/tissue volume (nBV/TV) in the cortical (14.9% and 5.4%) and the medullary (22.2% and 22.4%) region were not significantly different. One week of healing only resulted in negligible bone formation. These findings suggest that considering the large variation and the pilot nature of this study, magnetic implants failed to support peri-implant bone formation in a canine model
Osteoconductive Properties of a Volume-Stable Collagen Matrix in Rat Calvaria Defects: A Pilot Study
No full textVolume-stable collagen matrices (VSCM) are conductive for the connective tissue upon soft tissue augmentation. Considering that collagen has osteoconductive properties, we have investigated the possibility that the VSCM also consolidates with the newly formed bone. To this end, we covered nine rat calvaria circular defects with a VSCM. After four weeks, histology, histomorphometry, quantitative backscattered electron imaging, and microcomputed tomography were performed. We report that the overall pattern of mineralization inside the VSCM was heterogeneous. Histology revealed, apart from the characteristic woven bone formation, areas of round-shaped hypertrophic chondrocyte-like cells surrounded by a mineralized extracellular matrix. Quantitative backscattered electron imaging confirmed the heterogenous mineralization occurring within the VSCM. Histomorphometry found new bone to be 0.7 mm2 (0.01 min; 2.4 max), similar to the chondrogenic mineralized extracellular matrix with 0.7 mm2 (0.0 min; 4.2 max). Microcomputed tomography showed the overall mineralized tissue in the defect to be 1.6 mm3 (min 0.0; max 13.3). These findings suggest that in a rat cranial defect, VSCM has a limited and heterogeneous capacity to support intramembranous bone formation but may allow the formation of bone via the endochondral route
- …
