Bone Volume/tissue Volume Research Articles

Osseointegration evaluation of UHMWPE and PEEK-based scaffolds with BMP-2 using model of critical-size cranial defect in mice and push-out test

It the present study the push-out mechanical test was adopted for mouse model of implantation in critical-size cranial defects to evaluate the effectiveness of implant-skull fusion. As implants, disks of porous ultra-high molecular weight polyethylene (UHMWPE) and polyetheretherketone (PEEK) with hydroxylapatite (HA) with and without loading of recombinant bone morphogenetic protein-2 (BMP-2) were used. Implantation results were evaluated using histology and micro-computed tomography (micro-CT). In the case of both UHMWPE/HA and PEEK/HA, BMP-2 loading resulted in a significant increase in the amount of bone tissue in the implantation area, especially at the edges of the defect, and an increase in the value of BV/TV (bone volume/tissue volume) during micro-CT. There was a high correlation of BV/TV values with the maximum load and elastic modulus measured during the puch-out test. The maximum load values showed good convergence within the groups and are comparable to the maximum load values obtained by other authors in the rat model of implantation in critical-size cranial defects. An adapted push-out test can be used to evaluate the quality of osseointegration of the implanted materials.

Experimental study on repairing rabbit skull defect with bone morphogenetic protein 2 peptide/functionalized carbon nanotube composite

To observe and compare the effects of peptides on the repair of rabbit skull defects through two different binding modes of non-covalent and covalent, and the combination of carboxyl (-COOH) and amino (-NH 2) groups with materials. Twenty-one 3-month-old male ordinary New Zealand white rabbits were numbered 1 to 42 on the left and right parietal bones. They were divided into 5 groups using a random number table, the control group (group A, 6 sides) and the material group 1, 2, 3, 4 (respectively group B, C, D, E, 9 sides in each group). All animals were prepared with 12-mm-diameter skull defect models, and bone morphogenetic protein 2 (BMP-2) non-covalently bound multiwalled carbon nanotubes (MWCNT)-COOH+poly ( L-lactide) (PLLA), BMP-2 non-covalently bound MWCNT-NH 2+PLLA, BMP-2 covalently bound MWCNT-COOH+PLLA, and BMP-2 covalently bound MWCNT-NH 2+PLLA were implanted into the defects of groups B, C, D, and E, respectively. At 4, 8, and 12 weeks after operation, the samples were taken for CT scanning and three-dimensional reconstruction, the ratio of bone tissue regeneration volume to total volume and bone mineral density were measured, and the histological observation of HE staining and Masson trichrome staining were performed to quantitatively analyze the volume ratio of new bone tissue. CT scanning and three-dimensional reconstruction showed that with the extension of time, the defects in groups A-E were filled gradually, and the defect in group E was completely filled at 12 weeks after operation. HE staining and Masson trichrome staining showed that the volume of new bone tissue in each group gradually increased with time, and regenerated mature bone tissue appeared in groups D and E at 12 weeks after operation. Quantitative analysis showed that at 4, 8, and 12 weeks after operation, the ratio of bone tissue regeneration volume to total volume, bone mineral density, and the volume ratio of new bone tissue increased gradually over time; and at each time point, the above indexes increased gradually from group A to group E, and the differences between groups were significant ( P<0.05). Through covalent binding and using -NH 2 to bound peptides with materials, the best bone repair effect can be achieved.

Interstitial fluid velocity is decreased around cortical bone vascular pores and depends on osteocyte position in a rat model of disuse osteoporosis.

Muscle paralysis induced with botulinum toxin (Botox) injection increases vascular porosity and reduces osteocyte lacunar density in the tibial cortical bone of skeletally mature rats. These morphological changes potentially affect interstitial fluid flow in the lacunar-canalicular porosity, which is thought to play a role in osteocyte mechanotransduction. The aim of this study was to investigate the effects of disuse-induced morphological changes on interstitial fluid velocity around osteocytes in the bone cortex. Micro-CT images from a previous study that quantified the effects of Botox-induced muscle paralysis on bone microarchitecture in skeletally mature rats were used to create high-resolution, animal-specific finite element models that included the vascular pores and osteocyte lacunae within the tibial metaphysis of Botox-injected (BTX, n = 8) and saline-injected control (CTRL, n = 8) groups. To quantify fluid flow, lacunar and canalicular porosities were modeled as fluid-saturated poroelastic materials, and boundary conditions were applied to simulate physiological loading. This modeling approach allowed a detailed quantification of the fluid flow velocities around osteocytes in a relatively large volume of bone tissue. The analysis demonstrated that interstitial fluid velocity at the vascular pore surfaces was significantly lower in BTX compared to CTRL because of the decreased vascular canal separation. No significant differences in average fluid velocity were observed at the osteocyte lacunae and no correlation was found between the fluid velocity and the lacunar density, which was significantly lower in BTX. Instead, the lacunar fluid velocity was dependent on the osteocyte's specific position in the bone cortex and its proximity to a vascular pore.

Effect of Age on Bone Structure Parameters in Laying Hens.

Simple SummaryLaying hens supply calcium to their eggshells via a process of dynamic bone formation and resorption called remodeling. As hens age, their bone becomes weak and brittle due to an imbalance in remodeling, resulting in bone disorders. Osteoporosis, characterized by bone mass loss and increased risk of fractures, is a serious problem in the egg industry, affecting both productivity and animal welfare. Nonetheless, the mechanisms of age-related osteoporosis remain unknown. We evaluated differences in bone structure between age groups, using microscopy and 3D imaging. Bone quality was reduced by an increase in porosity, with loss of volume, contributing to age-related osteoporosis.Changes in medullary and cortical bone structure with age remain unclear. Twenty Hy-Line W36 hens, 25 or 52 weeks of age, were euthanized, and both tibiae were collected when an egg was present in the magnum. Serial cross sections of the tibiae were stained with Alcian blue. The bones were scanned using micro-computed tomography. Trabecular width (Tb.Wi) was significantly higher (p < 0.05) in 25-week-old hens, whereas medullary bone tissue volume (TV) was significantly higher (p < 0.01) in 52-week-old hens. 25-week-old hens had significantly higher (p < 0.01) bone volume fraction (BVF = calcified tissue / TV). Moreover, the cortical bone parameters were significantly higher (TV and bone mineral content (BMC) at p < 0.05, and bone volume (BV) and BVF at p < 0.01) in younger hens. Open porosity and total porosity, which indicate less density, were significantly higher (p < 0.01) in older hens. Older hens showed significantly higher (p < 0.01) tibial diaphysis TV than younger hens. Younger hens had significantly higher (p < 0.01) BV, BVF and bone mineral density (BMD) of the tibial diaphysis. These findings reveal that reductions in medullary bone quality might be associated with age-related low estrogen levels and stimulation of osteoclastic bone resorption by parathyroid hormone. Cortical bone quality decreased with enlargement of the Haversian canals and loss of volume, with a longer egg-laying period leading to osteoporosis.

Особливості заміщення дефектів зубних рядів у осіб із захворюваннями тканин пародонта різного ступеня тяжкості

Resume. The high prevalence of periodontal disease causes the urgency of finding ways to improve methods of diagnosis, treatment and prevention of complications of this disease. The complex clinical picture requires a differentiated approach to the choice of orthopedic rehabilitation of such patients taking into account the patient's age, degree of pathological changes and activity of the pathological process with mandatory immobilization of movable teeth by different types of splints and splint dentures. Depending on the degree of pathological changes in periodontal tissues, the size and topography of dentition defects and the severity of destructive-resorptive processes in the alveolar bone, the replacement of dentition defects should be planned using dental implants and splinttype dentures. The aim of the study. Improving the effectiveness of orthopedic treatment of periodontal diseases, burdened by defects of the dentition through the differentiated use of dental implants and splinting structures. Materials and methods. A comprehensive clinical and laboratory examination of 237 patients with clinically diagnosed periodontitis I–III degree, burdened by partial loss of teeth. From the specified contingent of persons we carried out orthopedic treatment of 98 patients aged from 30 to 69 years with periodontal diseases of various severity, aggravated by defects of dentitions of various size and localization. Cone-beam computed tomography was used for objective quantitative and qualitative assessment of periodontal tissue and bone tissue of the edentulous jaw in individuals with various clinical forms of periodontal disease, to determine the relative densitometric density of bone tissue, when planning dental implantation and for control its results. The localization of supracontacts was determined by occlusion. Diagnosis and elimination of traumatic occlusion were performed according to Jenkelson and Schuller [3]. Evaluation of the stability of dental implants was performed by frequency – resonance analysis of the stability of dental implants using the Osstell ISQ device. Results. According to the results of examination of 237 people and the division of patients into three age groups, the clinical features of the pathological process in the age aspect were established. The results of computed tomography of the dental apparatus of the subjects showed that periodontal disease in the age aspect in the dynamics is accompanied by the severity of destructive-resorptive processes in the alveolar bone, which are manifested in a decrease in the relative densitometric density of bone marrow and bone loss. Orthopedic rehabilitation of this contingent of persons was performed with the use of biologically indifferent structural materials and splinting orthopedic structures, including splinting of abutment teeth, removable prosthetics and dental implantation, as well as accompanying physiotherapy of prostheses. In the case of periodontitis of I–II degree with sufficient volume and density of bone tissue in the area of the dentition defect, high clinical efficacy was shown by the use of dental implantation in the case of gradual loading of the dental implant using a superstructure of own development. In the presence of medium and large defects of the dentition on the background of periodontitis II–III severity in the presence of significant pathological mobility of abutment teeth and insufficient volume and density of bone tissue in the area of the defect sufficient clinical effectiveness showed the use of removable dentures own design. Conclusions. Periodontal diseases in the age aspect in the dynamics are accompanied by pronounced destructive-resorptive processes in the alveolar bone, which are manifested by a decrease in the relative densitometric density of bone tissue and progressive loss of height of the alveolar process. Timely application of dental implantation due to the dosed gradual occlusal load on the alveolar bone helps to preserve the structure of the alveolar bone and the height of the alveolar process. In the presence of medium and large defects of the dentition on the background of periodontitis II–III severity in the presence of significant pathological mobility of abutment teeth and insufficient volume and density of bone tissue in the area of the dentition defect, the use of removable dentures of splinttype design is shown. To prevent complications of prosthetics and prolong the use of orthopedic structures, it is advisable to use photodynamic maintenance therapy. Key words: periodontal tissue disease, dentition defect, dental implantation, splint-type denture.

Прогнозирование результатов внутрисинусовой имплантации

The study included 564 patients with a deficit in the volume of bone tissue of the alveolar process of the maxillary bone, which did not allow simultaneous installation of crestal implants. The work was carried out relying on modern forecasting systems based on an aggregate and quantitative assessment of the risk of intra- and postoperative complications, anatomical and physiological state of tissues and organs in the area of intervention. In the course of the study, a system for predicting the results of subaxillary augmentation was developed. Factors affecting the nature and frequency of complications in the immediate and long-term postoperative periods are highlighted. A comparative assessment of the functioning of the mucociliary clearance depending on the volume and location of the augmentate is given. Functional methods of investigation – spiral computed tomography and cone-beam computerized tomography – of maxillary bones, video endoscopy of the nasal cavity, study of mucociliary clearance, anterior active rhinomanometry were used. The assessment of the state of the augmentate, pneumatization of the maxillary sinuses, the anatomy of the nasal cavity, paranasal sinuses, the state of the maxillary sinus mucosa, the vertical volume of the walls of the maxillary sinus, and the evacuation capacity of the maxillary sinuses were evaluated. A score was determined for each of the studied parameters. Patterns of preoperative changes in the maxillary sinuses that led to complications in the postoperative period were identified. For each of these parameters, the amount of points collected can range from 1 to 5 points. The higher the score, the higher the probability of successful surgical treatment. If the sum of points is from 1 to 2, forecast of subaxillary augmentation is unfavourable, for 3 points is questionable, with a score of 4–5, the prognosis is favourable.

Overloaded Orthopedic Force Induces Condylar Subchondral Bone Absorption by Stimulating Rat Mesenchymal Stem Cells Differentiating into Osteoclasts via mTOR-Regulated RANKL/OPG Secretion in Osteoblasts.

Appropriate orthopedic force led to bone remodeling of mandibular condyle, while overloaded orthopedic force (OOF) induced condylar bone absorption. Bone absorption is ascribed to the imbalanced activities between osteoclasts (OCs) and osteoblasts (OBs), mechanism of which remains unclear. This study aimed to observe the condylar changes induced by OOF by mandible advancement appliance and to further investigate the role of mammalian target of Rapamycin (mTOR) and RANKL/OPG in osteoclastic differentiation of stem cells in vivo and in vitro. In vivo, the results of micro-CT analysis indicated that condylar bone resorption was induced by OOF through mandibular advancement appliance for 2 weeks and worsened time dependently. Morphologically, cartilage thickness was reduced, subchondral cortical bone line appeared not continuous, and subchondral bone exhibited irregular-shaped and owned uneven surface. The bone mineral density (BMD), bone volume/tissue volume (BV/TV), trabecular number (Tb.N), and trabecular thickness (Tb.Th) were decreased accomplished with the increased trabecular separation (Tb.Sp) determined by micro-CT. In addition, based on immunofluorescent labeling, OOF activated both OCs and OBs, but osteoclastogenesis prevailed over osteogenesis. The mTOR activation and ratio of RANKL/OPG in OBs were elevated by OOF. In vitro, the results of western blot and polymerase chain reaction (PCR) consistently suggested that the mTOR and RANKL/OPG ratio were upregulated by overloaded mechanical stretch. Pretreatment with mTOR inhibitor, rapamycin, could attenuate the activation of mTOR and the secretion of RANKL in OBs. Interestingly, based on the Trap staining, the supernatant of OBs exposed to OOF could promote osteoclastic differentiation of mesenchymal stem cells (MSCs), while its role was weakened by inhibition of mTOR in OBs. Collectively, OOF induced condylar bone absorption; in the process, osteoclastogenesis was prominent than osteogenesis. The activation of mTOR and secretion of RANKL/OPG were enhanced by OOF and were involved in promoting MSCs differentiating into OCs.

Repair and remodeling of partial-weightbearing, uninstrumented long bone fracture model in mice treated with low intensity vibration therapy

BackgroundWhile vibration therapy has shown encouraging results across many fields of medicine in the last decade, its role as originally envisioned for bone health remains uncertain. Especially regarding its efficacy in promoting fracture healing, mixed and incomplete outcomes suggest a need to clarify its potential. In particular, the definitive effect of vibration, when isolated from the confounding mechanical inputs of gait and stabilizing instrumentation, remains largely unknown. MethodsFour cohorts of C57BL/6 male mice underwent single-leg, open fibula fracture. Vibration was applied at 0.3 g to two groups for 20 min/d. At 3 and 6 weeks, fibulae were harvested for microcomputed tomography and 3-point bending to failure. FindingsIn bone volume and tissue volume, the groups at each healing time point were statistically not different. At 3 weeks, however, the ratio of bone-to-tissue volume was lower for the vibrated group than control. Likewise, while bone mineral density did not differ, tissue volume density was lowest with vibration. At 6 weeks, mean differences were nominal. Biomechanically, vibration consistently trended ahead of control in strength and stiffness, but did not achieve statistical significance. InterpretationAt this stage of therapeutic development, vibration therapy in isolation does not demonstrate a clear efficacy for bone healing, although further treatment permutations and translational uses remain open for investigation.

Nanostructured Carbonated Hydroxyapatite Associated to rhBMP-2 Improves Bone Repair in Rat Calvaria.

Many biomaterials are used for Bone Morphogenetic Proteins (BMPs) delivery in bone tissue engineering. The BMP carrier system’s primary function is to hold these growth factors at the wound’s site for a prolonged time and provide initial support for cells to attach and elaborate the extracellular matrix for bone regeneration. This study aimed to evaluate the nanostructured carbonated hydroxyapatite microspheres (nCHA) as an rhBMP-2 carrier on rats calvaria. A total of fifteen male Wistar rats were randomly divided into three groups (n = 5): clot (control group), rhBMP-2 associated with collagen membrane (COL/rhBMP-2) or associated with the microspheres (nCHA/rhBMP-2). After 45 days, the calvaria defect samples were evaluated through histological, histomorphometric, and SR-µCT analyses to investigate new-formed bone and connective tissue volume densities. The descriptive histological analysis showed that nCHA/rhBMP-2 improved bone formation compared to other groups. These results were confirmed by histomorphometric and SR-µCT analysis that showed substantially defect area filling with a higher percentage of newly formed (36.24 ± 6.68) bone than those with the COL/rhBMP-2 (0.42 ± 0.40) and Clot (3.84 ± 4.57) (p < 0.05). The results showed that nCHA is an effective carrier for rhBMP-2 encouraging bone healing and an efficient alternative to collagen membrane for rhBMP-2 delivery.

Rehabilitation of the alveolar bone after tooth extraction. Analysis of methods

Resorption of the alveolar bone after tooth extraction is an irreversible process due to biological bone remodeling. It will greatly complicate the further treatment of patients for dental implantation, since for the latter a prerequisite is a sufficient volume of bone tissue. It leads to a protracted treatment process: the volume and timing of interventions increases. The literature review has shown possible methods of preservation of the alveolar ridge after tooth extraction and the results of their application.

Less mechanical loading attenuates osteoarthritis by reducing cartilage degeneration, subchondral bone remodelling, secondary inflammation, and activation of NLRP3 inflammasome.

AimsOsteoarthritis (OA) is a disabling joint disorder and mechanical loading is an important pathogenesis. This study aims to investigate the benefits of less mechanical loading created by intermittent tail suspension for knee OA.MethodsA post-traumatic OA model was established in 20 rats (12 weeks old, male). Ten rats were treated with less mechanical loading through intermittent tail suspension, while another ten rats were treated with normal mechanical loading. Cartilage damage was determined by gross appearance, Safranin O/Fast Green staining, and immunohistochemistry examinations. Subchondral bone changes were analyzed by micro-CT and tartrate-resistant acid phosphatase (TRAP) staining, and serum inflammatory cytokines were evaluated by enzyme-linked immunosorbent assay (ELISA).ResultsOur radiographs showed that joint space was significantly enlarged in rats with less mechanical loading. Moreover, cartilage destruction was attenuated in the less mechanical loading group with lower histological damage scores, and lower expression of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-5, matrix metalloproteinase (MMP)-3, and MMP-13. In addition, subchondral bone abnormal changes were ameliorated in OA rats with less mechanical loading, as reduced bone mineral density (BMD), bone volume/tissue volume (BV/TV), and number of osteophytes and osteoclasts in the subchondral bone were observed. Finally, the level of serum inflammatory cytokines was significantly downregulated in the less mechanical loading group compared with the normal mechanical loading group, as well as the expression of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3), caspase-1, and interleukin 1β (IL-1β) in the cartilage.ConclusionLess mechanical loading alleviates cartilage destruction, subchondral bone changes, and secondary inflammation in OA joints. This study provides fundamental insights into the benefit of non-weight loading rest for patients with OA.Cite this article: Bone Joint Res 2020;9(10):731–741.

Inflammation-mediated age-dependent effects of casein kinase 2-interacting protein-1 on osteogenesis in mesenchymal stem cells.

BackgroundThe casein kinase 2-interacting protein-1 (CKIP-1) is important in the development of osteoblasts and cardiomyocytes. However, the effects of CKIP-1 on osteoblast precursor mesenchymal stem cells (MSCs) remain unclear. This study aimed to determine whether CKIP-1 affects osteogenic differentiation in MSCs and explore the relationship of CKIP-1 and inflammation.MethodsBone marrow MSCs of CKIP-1 wild type (WT) and knockout (KO) mice were cultivated in vitro. Cell phenotype was analyzed by flow cytometry, colony formation was detected to study the proliferative ability. Osteogenic and adipogenic induction were performed. The osteogenic ability was explored by alizarin red staining, alkaline phosphatase (ALP) staining and ALP activity detection. Quantitative real-time polymerase chain reaction (qRT-PCR) was carried out to determine the mRNA expression levels of osteoblast marker genes. The adipogenic ability was detected by oil red O staining. Content of the bone was analyzed to observe the differences of bone imaging parameters including trabecular bone volume/tissue volume (BV/TV), bone surface area fraction/trabecular BV, trabecular number (Tb.N), and trabecular spacing (Tb.sp). Interleukin (IL)-1β was injected on WT mice of 2 months old and 18 months old, respectively. Difference in CKIP-1 expression was detected by RT-PCR and western blot. The relationship between CKIP-1 and inflammation was explored by RT-PCR and western blot.ResultsALP assays, alizarin red staining, and qRT-PCR showed that MSCs derived from CKIP-1 KO mice exhibited a stronger capability for osteogenesis. Micro-computed tomography detection showed that among 18-month-old mice, CKIP-1 KO mice presented significantly higher bone mass compared with WT mice (P = 0.02). No significant difference was observed in 2-month-old mice. In vivo data showed that expression of CKIP-1 was higher in the bone marrow of aging mice than in young mice (4.3-fold increase at the mRNA level, P = 0.04). Finally, the expression levels of CKIP-1 in bone marrow (3.2-fold increase at the mRNA level, P = 0.03) and cultured MSCs were up-regulated on chronic inflammatory stimulation by IL-1β.ConclusionsCKIP-1 is responsible for negative regulation of MSC osteogenesis with age-dependent effects. Increasing levels of inflammation with aging may be the primary factor responsible for higher expression levels of CKIP-1 but may not necessarily affect MSC aging.

Osseous evidence behind micro-osteoperforation technique in accelerating orthodontic tooth movement: A 3-month study

The study aimed to investigate the effects of micro-osteoperforations (MOPs) on the mandibular bone volume/tissue volume (BV/TV) ratio changes and the rate of orthodontic tooth movement using cone-beam computed tomography images. Another objective was to evaluate the effects of MOP frequency intervals (4weeks, 8weeks, and 12weeks) on the BV/TV ratio and rate of tooth movement. In 24 participants, 140-200g of force was applied for mandibular canine retraction. Three MOPs were made according to the scheduled intervals of the 3 different groups: group 1 (MOP 4weeks), group 2 (MOP 8weeks), and group 3 (MOP 12weeks) directly at the mandibular buccal cortical bone of extracted first premolars sites. Cone-beam computed tomography scans were obtained at the 12th week after MOP application. Computed tomography Analyzer software (version 1.11.0.0; Skyscan, Kontich, Belgium) was used to compute the trabecular alveolar BV/TV ratio. A significant difference was observed in the rate of canine movement between control and MOP. Paired t test analysis showed a significant difference (P=0.001) in the mean BV/TV ratio between control and MOP sides in all the frequency intervals groups. However, the difference was significant only in group 1 (P=0.014). A strong negative correlation (r=-0.86) was observed between the rate of canine tooth movement and the BV/TV ratio at the MOP side for group 1 and all frequency intervals together (r=-0.42). The rate of orthodontic tooth movement can be accelerated by the MOP technique with frequently repeated MOPs throughout the treatment.

Crossfibrillar mineral tessellation in normal and Hyp mouse bone as revealed by 3D FIB-SEM microscopy

In bone, structural components such as mineral extend across length scales to provide essential biomechanical functions. Using X-ray micro-computed tomography (µCT), and focused ion beam scanning electron microscopy (FIB-SEM) in serial-surface-view mode, together with 3D reconstruction, entire mouse skeletons and small bone tissue volumes were examined in normal wildtype (WT) and mutant Hyp mice (an animal model for X-linked hypophosphatemia/XLH, a disease with severe hypomineralization of bone). 3D thickness maps of the skeletons showed pronounced irregular thickening and abnormalities of many skeletal elements in Hyp mice compared to WT mice. At the micro- and nanoscale, near the mineralization front in WT tibial bone volumes, mineralization foci grow as expanding prolate ellipsoids (tesselles) to abut and pack against one another to form a congruent and contiguous mineral tessellation pattern within collagen bundles that contributes to lamellar periodicity. In the osteomalacic Hyp mouse bone, mineralization foci form and begin initial ellipsoid growth within normally organized collagen assembly, but their growth trajectory aborts. Mineralization-inhibiting events in XLH/Hyp (low circulating serum phosphate, and increased matrix osteopontin) combine to result in decreased mineral ellipsoid tessellation – a defective mineral-packing organization that leaves discrete mineral volumes isolated in the extracellular matrix such that ellipsoid packing/tessellation is not achieved. Such a severely altered mineralization pattern invariably leads to abnormal compliance, other aberrant biomechanical properties, and altered remodeling of bone, all of which indubitably lead to macroscopic bone deformities and anomalous mechanical performance in XLH/Hyp. Also, we show the relationship of osteocytes and their cell processes to this mineralization pattern.

Effect of periosteal resection on longitudinal bone growth in a mouse model of achondroplasia

Achondroplasia (ACH) is the most common form of short-limbed skeletal dysplasia. Patients with ACH sometimes undergo lower limb lengthening to get functional and psychological achievements. The periosteal resection (PR) is a known mechanism to increase longitudinal bone growth without osteotomy, although the results are not predictable. It could be alternative for limb lengthening in a minimally invasive technique. The purpose of this study is to evaluate the effect of PR on acceleration of bone growth in a mouse model of ACH (Fgfr3ach). We performed a circumferential resection of periosteum on the proximal tibia to both wild-type and Fgfr3ach mice at the age of four weeks. The second PR was done one week later in each mouse, which was subsequently sacrificed at the age of six weeks for micro-computed tomography (micro-CT) scan and histological examinations. We measured tibial bone length, bone volume, and metaphyseal trabecular bone parameters, including bone volume/tissue volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N) by reconstructed micro-CT images. We also quantified the entire width of the growth plate of the proximal tibial from the sections stained with hematoxylin and eosin. Tibial bone length and bone volume of the PR side were significantly larger than the sham side in wild-type mice, while they were not statistically significant in Fgfr3ach mice. The BV/TV and Tb.N in the metaphysis were significantly decreased in the PR side of both mice. The histological analysis revealed that the growth plate of the proximal tibia was significantly wider in the PR side of wild-type mice while it showed no difference in width between the PR side and the sham side in Fgfr3ach mice. PR promoted longitudinal bone growth in wild-type mice, but it exhibited only a marginal effect on bone growth in Fgfr3ach mice.

Modified Two-Stage Split Technique for Controlled Ridge Augmentation in Horizontally Atrophic Posterior Mandible: the First Stage of Research.

Various bone grafting methods are applied to eliminate horizontal atrophy of the jaws. However, problem complexity brings about ongoing research and development of new ways to achieve the predicted stable and long-term results of implantological treatment.The aim of the study was to evaluate the results of the developed method for bone grafting, a modified two-stage split technique for controlled ridge augmentation in horizontally atrophic posterior mandible, using radiological analysis data.Materials and Methods.The study group included 18 patients with horizontally atrophic posterior mandible. According to cone beam computed tomography, 39 jaw segments were assessed before plastic surgery and after applying the two-stage split-crest technique for controlled ridge augmentation. The alveolar ridge width was estimated in the area of its top and at a distance of 1, 3, 5 mm from it using the vector of future implant position and taking into account the angle of inclination of the atrophic region of the mandible.Results.When analyzing edentulous areas in the posterior mandible before treatment, there was rather a large angle of lingual inclination of the alveolar ridge. After 6 months, the average increase in bone tissue width in the region of the alveolar ridge top was 82%, it was 50.6% at a height of 1 mm from the top of the crest, 58.8% at 3 mm height, 46.7% at 5 mm (p≤0.05). Certain patterns of bone tissue growth were revealed depending on the structure of the reconstructed area. The most significant results were obtained in the molar segments of the mandible.Conclusion.The developed modified two-stage split technique for alveolar ridge augmentation allows achieving the required volume of bone tissue in the posterior mandible for successful implant treatment.

The loss of STAT3 in mature osteoclasts has detrimental effects on bone structure.

Signal Transducer and Activator of Transcription 3 (STAT3) has recently been shown to be involved in bone development and has been implicated in bone diseases, such as Job’s Syndrome. Bone growth and changes have been known for many years to differ between sexes with male bones tending to have higher bone mass than female bones and older females tending to lose bone mass at faster rates than older males. Previous studies using conditional knock mice with Stat3 specifically deleted from the osteoblasts showed both sexes exhibited decreased bone mineral density (BMD) and strength. Using the Cre-Lox system with Cathepsin K promotor driving Cre to target the deletion of the Stat3 gene in mature osteoclasts (STAT3-cKO mice), we observed that 8-week old STAT3-cKO female femurs exhibited significantly lower BMD and bone mineral content (BMC) compared to littermate control (CN) females. There were no differences in BMD and BMC observed between male knock-out and male CN femurs. However, micro-computed tomography (μCT) analysis showed that both male and female STAT3-cKO mice had significant decreases in bone volume/tissue volume (BV/TV). Bone histomorphometry analysis of the distal femur, further revealed a decrease in bone formation rate and mineralizing surface/bone surface (MS/BS) with a significant decrease in osteoclast surface in female, but not male, STAT3-cKO mice. Profiling gene expression in an osteoclastic cell line with a knockdown of STAT3 showed an upregulation of a number of genes that are directly regulated by estrogen receptors. These data collectively suggest that regulation of STAT3 differs in male and female osteoclasts and that inactivation of STAT3 in osteoclasts affects bone turnover more in females than males, demonstrating the complicated nature of STAT3 signaling pathways in osteoclastogenesis. Drugs targeting the STAT3 pathway may be used for treatment of diseases such as Job’s Syndrome and osteoporosis.

Bone defect reconstruction with a novel biomaterial containing calcium phosphate and aluminum oxide reinforcement

BackgroundReconstruction of metaphyseal fractures represents a clinical challenge for orthopedic surgeons. Especially in osteoporotic bone, these fractures are frequently accompanied by osseous substance defects. In order to ensure rapid mobilization of patients, high stability requirements must be met by osteosynthesis. Various bone graft materials have been introduced in the past, such as autologous bone or exogenous bone substitute materials. These are used as bone void fillers or as augmentation techniques to ensure safe fixation of osteosynthesis. New calcium phosphate-based bone void-filling materials could be a promising alternative to autologous bone or to the currently and widely used polymethylmethacrylate (PMMA)-based cement. The aim of this study was to evaluate a novel paste-like bone void filler in vivo and in vitro with regard to biocompatibility and osteoconductivity.MethodsIn addition to in vitro testing of cell compatibility using pre-osteoblasts (MC3T3-E1), 35 Wistar rats were treated in vivo with implantation of various material mixtures based on calcium phosphate and aluminum oxide reinforcement in a metaphyseal drill hole defect. After 4 weeks, an examination by micro-computed tomography (μCT) and histology was performed.ResultsThe in vitro analysis showed good biocompatibility with a high cell survival of osteoblasts. In the in vivo experiments, a significantly higher bone ingrowth compared to the empty defect was shown by μCT and histological analysis. Here, the group receiving material reinforced with aluminum oxide (Al2O3) showed a bone volume/tissue volume (BV/TV) of 89.19% compared to a BV/TV of 83.14% for the empty defect (p = 0.0013). In the group treated with a polysaccharide matrix, no increase in BV/TV was observed given a mean ratio of 80.14%. Scoring of histological sections did not reveal a significant difference between CaP and CaP that was substituted with Al2O3.ConclusionThe results of this study show an encouraging first step towards the development of new pasty, bone void-filling materials. We demonstrated that a new paste-like bone-filling material, based on calcium phosphate granulates and aluminum oxide to provide strength, exhibits good biocompatibility and osteoconductivity. Further biomechanical test in an osteoporotic animal model will have to be performed, to prove feasibility in metaphyseal defects.

Self-emulsifying formulation of Spinacia oleracea reduces the dose and escalates bioavailability of bioactive compounds to accelerate fracture repair in rats

BackgroundSpinach (Spinacia oleracea) is a rich source of flavonoids and therefore widely used therapeutically as an antioxidant agent in traditional medicine. The present study was undertaken to study the bone regenerating property of dried Spinacia oleracea extract (DSE) and self-emulsifying formulation of the extract (FDSE) on drill-hole model of fracture repair in rats.Methods0.8 mm hole was drilled in the diaphyseal region of femur in adult SD rats. DSE and formulated extract (FDSE) was administered orally and fractured femur was collected after treatment regimen. Micro-CT, transcriptional analysis and measurement of calcein intensity of callus formed at the injured site was performed to study the efficacy of the extract and formulation on bone regeneration. Further, compounds from extract were assessed for in-vitro osteoblast activity.ResultsMicro-architecture of the regenerated bone at injured site exhibited 26% (p < 0.001) and 35% (p < 0.01) increased BV/TV (bone volume /tissue volume) and Tb.N. (trabecular number) for DSE (500 mg.kg− 1). Further, FDSE exhibited similar augmentation in BV/TV (p < 0.01) and Tb. N (p < 0.01) parameters at dose of 250 mg.kg− 1. Analogous results were obtained from transcriptional analysis and calcein intensity at the fractured site. 3-O-Methylpatuletin, one of the compound isolated from the extract stimulated the differentiation and mineralization of primary osteoblast and depicted concentration dependent antagonizing effect of H2O2 in osteoblast apparently, minimizing ROS generation thus affectivity in fracture repair.ConclusionsThe present study showed that bone regenerating property of spinach was augmented by formulating extract to deliverable form and can be further studied to develop as therapeutic agent for fracture repair.Graphical abstract

Pyk2 deficiency enhances bone mass during midpalatal suture expansion.

To determine if Pyk2 deficiency increases midpalatal suture bone mass and preserves sutural integrity after maxillary expansion. Thirty-six male Pyk2 knockout (KO) and control (WT) mice at 6weeks of age. Mice received nickel-titanium spring expanders delivering 0g (no intervention control), 10 or 20g force for 14days. High-resolution micro-CT was used to determine bone volume/tissue volume (BV/TV), sutural width and intermolar width. Effects on osteoclasts, chondrocytes and suture morphology were determined by histomorphometry. Pyk2-KO controls (0g) had 7% higher BV/TV compared with WT controls. Expanded Pyk2-KO maxillae also exhibited 12% (10g) and 18% (20g) higher BV/TV than WT mice. Although bone loss following expansion occurred in both genotypes, BV/TV was decreased to a greater extent in WT maxillae (-10% at 10g; -22% at 20g) compared with Pyk2-KO maxillae (-11% only at 20g). Expanded WT maxillae also showed a greater increase in sutural width, intermolar width and fibrous connective tissue width compared with expanded Pyk2-KO maxillae. Moreover, osteoclast number was increased 77% (10g) and 132% (20g) in expanded WT maxillae, but remained unchanged in expanded Pyk2-KO, compared to their respective controls. Cartilage area and chondrocyte number were increased to the same extent in expanded WT and Pyk2-KO sutures. These findings suggest that midpalatal suture expansion increases osteoclast formation in WT but not Pyk2-KO mice, leading to higher BV/TV in expanded Pyk2-KO maxillae. These studies suggest Pyk2-targeted strategies may be beneficial to increase bone density and preserve sutural integrity during maxillary expansion.