Revisión sistemática de los efectos de microvibración de baja magnitud alta frecuencia en osteocitos cultivados / Systematic review of the effects of low intensity high frequency microvibration on osteocytes cultivated

Introducción: El hueso, reservorio de minerales y moléculas orgánicas, es un tejido dinámico que detecta y se adapta a las cargas mecánicas de los órganos y tejidos del cuerpo, el cual mantiene la estructura ósea del esqueleto durante el crecimiento y a través de la vida del ser humano. Las células óseas son sensibles a las cargas mecánicas y microvibra- ciones que recibe el esqueleto. Objetivo: El propósito de este estudio fue realizar una revisión sistemática acerca de los efectos que ejerce la microvibración de alta frecuencia-baja intensidad, en osteocitos cultivados in vitro sobre la síntesis de factores solubles, con el propósito de entender si la microvibración tiene influencia en la aceleración del movimiento dentario. Material y métodos: Se realizó una búsqueda de artículos de revisión de osteocitos y otras células óseas in vitro, a través de la estrategia PICO (Paciente, Intervención, Comparación, Resultado [Outcome]), con el empleo de palabras clave como: «os- teocitos¼, «microvibración¼, «remodelación¼, «osteoclastogénesis¼, «citocinas¼ y «osteoblastos¼. Se estructuró por medio de PRISMA (informe de revisiones sistemáticas y meta-análisis). La captación de datos finales se hizo por medio del método de puntuación de calidad Jadad y Cochrane (modelo de correlación) como herramientas para evaluar el riesgo de sesgo de cada uno de los artículos. Se incluyeron 11 artículos con alta calidad metodológica. Resultados: La mayoría de los experimentos in vitro demostraron que la microvibración tuvo un aumento estadísticamente significativo en la proliferación y dife- renciación de las células madre mesenquimales (MSC), en osteoblastos (MC3T3-E1), en la expresión de proteínas para inducir osteogénesis y en los osteocitos (MLO-Y4). Asimismo, sobrerregularon la expresión de osteoprotegerina (OPG), prostaglandina (PGE2) y óxido nitroso (NO) al alterar y regular los factores solubles como las citocinas, factores de crecimiento y quimiocinas, de las demás células, además de mostrar una disminución en la actividad de los osteoclastos (RAW246.7) en la resorción ósea. Conclusión: La microvibración induce remodelación ósea. Los osteocitos son sensibles a los estímulos mecánicos y producen factores solubles para inducir la remodelación ósea, razón por la cual se emplea la microvibración como una terapia innovadora y prometedora, no invasiva y no farmacológica en la estimulación de la formación ósea de la superficie del hueso (AU)

Citotoxicidade e efeito indutor de mineralização de flavonoides sobre células osteoblásticas / Cytotoxicity and inducing effect of mineralization of flavonoids on osteoblastic cells

A perda óssea dentária e a formação de lesões periapicais surgem como uma consequênc ia do desequilíbrio da homeostase óssea. Os osteoblastos, juntamente com os osteoclastos e osteócitos, atuam na formação e na reabsorção óssea. Vários marcadores de formação óssea são produzidos por osteoblastos ativos e refletem diferentes aspectos da dif erenciação osteoblástica e da remodelação óssea. Com isso, muitos autores têm explorado o uso de fitoterápicos, visando obter novos compostos que apresentem propriedades terapêuticas, como os flavonoides, e que estimulem a neoformação óssea e o reparo da r egião periapical. O objetivo deste estudo foi avaliar in vitro a citotoxicidade e efeito indutor de mineralização de flavonoides sobre células osteoblásticas humanas. Para isso, células osteoblásticas da linhagem Saos expostas aos seguintes flavono2 foram ides: quercetina, miricetina e seus derivados taxifolina, isoquercitrina, rutina, ampelopsina e EGCG, além de pinocembrina, crisina e canferol, de forma isolada e combinada. Foi avaliado o efeito citotóxico, a atividade de fosfatase alcalina e indução de n mé todo de Shapiroódulos de mineralização. Os resultados foram analisados p elo Wilk, e as variáveis foram submetidas à análise de ANOVA seguida pelo teste de Tukey para comparar entre os grupos e/ou concentrações ou teste de Dunnett para comparar entre cada grupo e o controle, com nível de significância de 5%. A viabilidade da cultura de osteoblastos não teve uma redução estatisticamente significativa na presença da maioria dos compostos, exceto crisina a 100µM. Taxifolina, isoquercitrina, rutina, ampelopsina e EGCG foram os compostos que estimularam significativamente a atividade da fosfatase alcalina, juntamente com as combinações taxifolina+isoquercitrina, taxifolina+ampelopsina e taxifolina+rutina a 25/25 µM. Quanto a formação de nódulos de mine ralização, ampelopsina, isoquercitrina, rutina, pinocembrina e miricetina isolados e taxifolina+isoquercitrina, taxifolina+ampelopsina e taxifolina+rutina combinados obtiveram os melhores resultados, variando de acordo com as concentrações. Concluise que a taxifolina, isoquercitrina, rutina e ampelopsina e combinações de taxifolina com esses flavonoides são citocompatíveis e apresentam efeito indutor de mineralização em osteoblastos Saos-2(AU)

Dental bone loss and the formation of periapical lesions arise as a consequence of imbalance of bone homeostasis. Osteoblasts, together with osteoclasts and osteocytes, act in bone formation and resorption. Several markers of bone formation are produced by active osteoblasts and reflect different aspects of osteoblastic differentiation and bone remodeling. Thus, many authors have explored the use of phytotherapics in order to obtain new compounds with therapeutic properties, such as flavonoids, and also stimulate bone neoformation and periapical region repair. The objective of this study was to evaluate in vitro the cytotoxicity and inducing effect of flavonoid mineralization on human osteoblastic cells. For this, osteoblastic cells of the Saos-2 lineage were exposed to the following flavonoids: quercetin, myricetin and its derivatives taxifoline, isoquercitrin, rutin, ampelopsin and EGCG, in addition to pinocembrin, chrysin and kaempferol, in an isolated and combined manner. The cytotoxic effect, the activity of alkaline phosphatase and the induction of mineralization nodules were evaluated. The results were analyzed using the Shapiro-Wilk method, and the variables were submitted to ANOVA analysis followed by the Tukey test to compare between groups and/or concentrations or Dunnett's test to compare between each group and the control, with a level of 5% significance. The viability of the osteoblast culture did not have a statistically significant reduction in the presence of most compounds, except 100 µM chrysin. Taxifoline, isoquercitrin, rutin, ampelopsin and EGCG were the compounds that significantly stimulated the activity of alkaline phosphatase, together with the combinations taxifoline+isoquercitrin, taxifoline+ampelopsin and taxifoline+rutin at 25/25 µM. As for the formation of mineralization nodules, ampelopsin, isoquercitrin, rutin, pinocembrin and myricetin alone and taxifoline+isoquercitrin, taxifoline+ampelopsin and taxifoline+rutin combined obtained the best results, varying according to the concentrations. It is concluded that taxifoline, isoquercitrin, rutin and ampelopsin and combinations of taxifolin with these flavonoids are cytocompatible and have a mineralization-inducing effect on Saos-2 osteoblasts(AU)

Effects of salbutamol, montelukast and prednisone on orthodontic tooth movement in rats / Efeitos do salbutamol, montelucaste e prednisona no movimento dentário ortodôntico em ratos

Objective: To evaluate the effect of salbutamol, montelukast, and prednisone on orthodontic tooth movement in rats. Material and Methods: In vivo experimental preclinical study. The sample consisted of 48 rats randomly distributed in four study groups. Group A was given saline solution; to group B, salbutamol 4 mg/Kg; to group C, montelukast 2.5 mg/Kg and to group D, prednisone 2.5 mg/Kg. All were fitted with orthodontic devices and the medications were administered intraperitoneally every 12 hours for 5 days. The clinical evaluation (variation in the interincisal distance) was performed at one, three, five, and seven days and the histopathological analysis (cell count) at five and seven days. Results: In the clinical evaluation of the variation in the interincisal distance, a significant difference was found in all the evaluations (p <0.05). It was found that the salbutamol group presented higher variation values in the interincisal distance on all the days evaluated. In the histopathological analysis at five and seven days, it was found that the osteoblast and osteocyte count was significantly higher in the salbutamol group compared to the other groups (p <0.05). However, in the subgroup analysis, it was found that there was no significant difference in the osteoblast and osteocyte count between the prednisone, montelukast, and control group (p> 0.05). Conclusion: The administration of salbutamol increased the magnitude of orthodontic tooth movement; nonetheless, the administration of montelukast and prednisone did not modify the magnitude of orthodontic tooth movement in rats. (AU)

Objetivo: Avaliar o efeito do salbutamol, montelucaste e prednisona no movimento dentário ortodôntico em ratos. Material e métodos: Estudo pré-clínico experimental in vivo. A amostra foi composta por 48 ratos distribuídos aleatoriamente em quatro grupos de estudo. O grupo A recebeu solução salina; para o grupo B, salbutamol 4 mg/kg; ao grupo C, montelucaste 2,5 mg/kg e ao grupo D, prednisona 2,5 mg/kg. Todos foram equipados com dispositivos ortodônticos e os medicamentos foram administrados por via intraperitoneal a cada 12 horas por 5 dias. A avaliação clínica (variação da distância interincisal) foi realizada em um, três, cinco e sete dias e a análise histopatológica (contagem de células) em cinco e sete dias. Resultados: Na avaliação clínica da variação da distância interincisal, houve diferença significativa em todas as avaliações (p <0,05). Verificou-se que o grupo salbutamol apresentou maiores valores de variação na distância interincisal em todos os dias avaliados. Na análise histopatológica aos cinco e sete dias, verificou-se que a contagem de osteoblastos e osteócitos foi significativamente maior no grupo salbutamol em comparação aos demais grupos (p<0,05). No entanto, na análise de subgrupos, verificou-se que não houve diferença significativa na contagem de osteoblastos e osteócitos entre os grupos prednisona, montelucaste e controle (p>0,05). Conclusão: A administração de salbutamol aumentou a magnitude do movimento dentário ortodôntico; no entanto, a administração de montelucaste e prednisona não modificou a magnitude do movimento dos dentes ortodônticos em ratos. (AU)

Expression of CD44 in previously grafted alveolar bone / Expresión del marcador óseo CD44 en hueso alveolar previamente injertado

Objetive: To determine the expressions of the bone surface marker CD44 in samples of alveolar bone previously regenerated with allograft, xenograft, and mixed, using the technique of guided bone regeneration. Material and Methods: This exploratory study was approved by the institutional research and ethics committee. By means of intentional sampling and after obtaining informed consent for tissue donation, 20 samples of alveolar bone previously regenerated with guided bone regeneration therapy with particulate bone graft and membrane were taken during implant placement. The samples were stained with hematoxylin-eosin for histological analysis, and by immunohistochemistry for the detection of CD44. Results: Sections with hematoxylin-eosin showed bone tissue with the presence of osteoid matrix and mature bone matrix of usual appearance. Of the CD44+ samples, 80% were allograft and 20% xenograft. The samples with allograft-xenograft were negative. There were no differences in the intensity of CD44 expression between the positive samples. The marker was expressed in osteocytes, stromal cells, mononuclear infiltrate, and some histiocytes. Eighty percent of the CD44+ samples and 100% of the samples in which 60 or more cells were labelled corresponded to allografts (p=0.000). A total of 67% of the samples from the anterior sector, and 40% from the posterior sector were CD44+ (p=0.689). Conclusion: This study shows for the first time that guided bone regeneration using allografts is more efficient for the generation of mature bone determined by the expression of CD44, compared to the use of xenografts and mixed allograft-xenograft, regardless of the regenerated anatomical area.

Objetivo: Determinar la expresión del marcador de membrana óseo CD44 en muestras de hueso alveolar previamente regenerado con aloinjerto, xenoinjerto y mezcla mediante la técnica de regeneración ósea guiada. Material y Métodos: Con aval del Comité de Investigación y Ética, se realizó un estudio exploratorio. Por muestreo intencional y firma de consentimiento informado de donación, se tomaron durante la colocación del implante, 20 muestras de hueso alveolar previamente regenerado con terapia de regeneración ósea guiada con injerto óseo particulado y membrana. Las muestras fueron teñidas con hematoxilina-eosina para el análisis histológico y por inmunohistoquímica para la detección del CD44. Resultados: : Los cortes con hematoxilina-eosina mostraron tejido óseo con presencia de matriz osteoide y matriz ósea madura de aspecto usual. De las muestras CD44+, 80% fueron de aloinjerto y 20% de xenoinjerto. Las muestras con aloinjerto-xeoninjerto fueron negativas. No hubo diferencias en la intensidad de la expresión del CD44 entre las muestras positivas. El marcador se expresó en osteocitos, células estromales, infiltrado mononuclear y algunos histiocitos. El 80% de las muestras CD44+ y el 100% de las muestras con marcación de 60 o más células correspondían a aloinjertos (p=0,000). El 67% de las muestras del sector anterior y el 40% del sector posterior fueron CD44+ (p=0,689). Conclusión: Este estudio muestra por primera vez que la regeneración ósea guiada usando aloinjertos, es más eficiente para la generación de hueso maduro determinado por la expresión de CD44, comparado con el uso de xenoinjertos y mezcla de aloinjerto-xenoinjerto, independientemente del sector anatómico regenerado.

Micro-ARNs y células óseas / Micro RNAs and bone cells

Los micro-ARNs (miARNs) son pequeñas moléculas de ARN no codificante (de aproximadamente 15-25 nucleótidos), que regulan la expresión de genes involucrados en numerosas funciones biológicas, a través de la inhibición o degradación de un ARN mensajero diana. La homeostasis ósea se mantiene por el balance entre la formación osteoblástica y la resorción osteoclástica. La sobreexpresión o inhibición de miARNs específicos afecta la proliferación, diferenciación y actividad de osteoblastos, osteocitos y osteoclastos. Estas acciones son llevadas a cabo modulando la expresión de distintos factores transcripcionales y moléculas de señalización de las vías esenciales para la osteoblastogénesis u osteoclastogénesis. Estos efectos modifican el balance entre la formación y la resorción, determinando cambios en la homeostasis ósea. Esta revisión enumera una serie de miARNs que participan en la homeostasis ósea. Profundizando en el conocimiento de los mecanismos por medio de los cuales los miARNs actúan sobre el hueso, podrían revelarse nuevos usos potenciales futuros, entre los que se encuentran su utilidad como nuevos biomarcadores óseos o como agentes terapéuticos para el tratamiento de trastornos metabólicos óseos, pérdida de masa ósea o enfermedades óseas. (AU)

MicroRNAs (miRNAs) are endogenous small noncoding RNA molecules (of approximately 15­25 nucleotides), which regulate the expression of genes controlling numerous biological functions, through the inhibition or degradation of the target messenger RNA. Bone homeostasis is maintained by a balance between osteoblastic bone formation and osteoclastic bone resorption. The overexpression or inhibition of specific miRNAs affects cell proliferation, differentiation and activity of osteoblast, osteocytes and osteoclast. This action is done by modulating the expression of different transcription factors and signaling molecules of the most relevant pathways of osteoblastogenesis or osteoclastogenesis. This effect is able to modify the balance between bone formation and resorption, determining changes in bone homeostasis. The present review is an overview of a series of miRNAs involved in bone homeostasis. An in depth knowledge of the mechanisms by which miRNAs act on bone may reveal potential uses in the future as new bone biomarkers or therapeutic agents for treating metabolic bone disorders, bone loss and bone diseases. (AU)

Efeito da administração local e sistêmica da atorvastatina no reparo ósseo de defeitos críticos em calvária de ratos / Effect of local or systemic administration of atorvastatin on bone repair of critical defects in rats' calvaria

Objetivo: O presente estudo teve como objetivo comparar o efeito da Atorvastatina, aplicada de forma local e sistêmica, em defeitos críticos de calotas de ratos. Material e médodos: 36 (trinta e seis) ratos (Rattus norvegicus, albinus, Wistar), adultos foram divididos aleatoriamente em 3 grupos, o grupo aplicação de membrana de colágeno com água destilada (GAD) com defeitos de tamanho crítico contendo água destilada; o grupo aplicação Sistêmica de Atorvastatina (GAS) foram realizado defeitos de tamanho crítico e os animais foram tratados com atorvastatina (3,6mg/kg/dia) por gavagem; e o grupo de aplicação local de Atorvastatina (GAL) com defeitos de tamanho crítico contendo Atorvastatina. Cada grupo foi avaliado através da histometria, mensuração do defeito residual, área de osso néo formado (AON), área de membrana e tecido mole, contagem de células (osteócitos, osteoblastos, células inflamatórias) e imunoistoquímica (OSTEOCALCINA e CD31), nos períodos de 14 e 28 dias. Resultados: Os dados mostraram diminuição do defeito residual para GAS quando comparada ao GAL (p=0,024) e ao GAD (p=0,033), o GAS revelou diminuição de número de osteócitos em comparação ao GAD (p=0,026), e em comparação com GAL (p=0,020). Os osteoblastos não apresentaram diferença entre os grupos (p>0,05), a quantidade de fibroblastos mostrou maiores somente para o GAL de 14 para 28 dias (p=0,019). Aos 28 dias, tanto para GAL quanto GAS, a quantidade de células inflamatórias foram maiores comparadas ao GAD (p< 0,05). A marcação de imunoistoquimica para CD31 não apresentou alteração, e OCN nos osteoblastos mostrou maior imunomarcação aos 14 dias em comparação aos 28 dias somente para o GAS (p=0,026; Holm-Sidak), OCN na marcação da matriz extra celular (MEC) mostrou aumento da imunomarcação aos 14 quando comparado aos 28 dias no GAL e GAS (p=0,041; Holm-Sidak). Conclusão: A Atorvastatina promoveu efeito positivo na osteogênese e sugere-se que ela não exerça função anti-inflamatória(AU)

Objective: This study aimed to compare the effect of Atorvastatin, applied locally and systemically, on critical defects of rat caps. Material and medicaments: 36 (thirty-six) rats (Rattus norvegicus, albinus, Wistar), adults were randomly divided into 3 groups, the collagen membrane application group with distilled water (GAD) with critical size defects containing distilled water; the systemic application group of Atorvastatin (GAS) was performed with critical size defects and the animals were treated with atorvastatin (3.6mg/kg/day) per gavage; and the local application group of Atorvastatin (GAL) with critical size defects containing Atorvastatin. Each group was evaluated by histometry, measurement of the residual defect, area of neo formed bone (AON), area of membrane and soft tissue, cell count (osteocytes, osteoblasts, inflammatory cells) and immunohistochemistry (OSTEOCALCINE and CD31), in periods of 14 and 28 days. Results: The data showed a decrease of residual defect for GAS when compared to GAL (p=0.024) and GAD (p=0.033), GAS showed a decrease of osteocytes in comparison to GAD (p=0.026), and in comparison to GAL (p=0.020). The osteoblasts did not present difference between the groups (p>0.05), the amount of fibroblasts showed higher only for the GAL from 14 to 28 days (p=0.019). At 28 days, both for GAL and GAS, the amount of inflammatory cells were higher compared to GAD (p<0.05). The immunohistochemistry marking for CD31 showed no change, and CSF in osteoblasts showed higher immunomarkings at 14 days compared to 28 days only for GAS (p=0.026; Holm-Sidak), CSF in extra cellular matrix marking (SCM) showed increased immunomarkings at 14 days compared to 28 days in GAL and GAS (p=0.041; Holm-Sidak). Conclusion: Atorvastatin promoted a positive effect on osteogenesis and it is suggested that it does not have an anti-inflammatory function(AU)

Observation of dendrite osteocytes of mice at different developmental stages using Ploton silver staining and phalloidin staining / 南方医科大学学报

OBJECTIVE@#To assess the value of Ploton silver staining and phalloidin-iFlour 488 staining in observation of the morphology of osteocyte dendrites of mice at different developmental stages.@*METHODS@#The humerus and femurs were harvested from mice at 0 (P0), 5 (P5), 15 (P15), 21 (P21), 28 (P28), and 35 days (P35) after birth to prepare cryo-sections and paraffin sections. HE staining of P35 mouse femur sections served as a reference for observing osteocytes in the trabecular bone and cortical bone. The humeral sections at different developmental stages were stained with Ploton silver staining to observe the morphology of osteocytes and canaliculi, and the canalicular lengths in the cortical and trabecular bones of the humerus of the mice in each developmental stage were recorded. The cryo-sections of the humerus from P10 and P15 mice were stained with phalloidin iFlour-488 to observe the morphology of osteocytes and measurement of the length of osteocyte dendrites in the cortical bone.@*RESULTS@#In the trabecular bone of the humerus of P0-P15 mice, Ploton silver staining only visualized the outline of the osteocytes, and the morphology of the canaliculi was poorly defined. In P21 or older mice, Ploton silver staining revealed the morphology of the trabecular bone osteocytes and the canaliculi, which were neatly arranged and whose lengths increased significantly with age (P21 @*CONCLUSIONS@#Mouse osteocyte dendrites elongate progressively and their arrangement gradually becomes regular with age. Ploton silver staining can clearly visualize the morphology of the osteocytes and the canaliculi in adult mice but not in mice in early stages of development. Phalloidin iFlour-488 staining for labeling the cytoskeleton can be applied for mouse osteocytes at all developmental stages and allows morphological observation of mouse osteocytes in early developmental stages.

Inmunopatología de la brucelosis osteoarticular / Immunopathology of osteoarticular brucelosis

La brucelosis es una de las enfermedades zoonóticas más importantes a nivel mundial capaz de producir enfermedad crónica en los seres humanos. La localización osteoarticular es la presentación más común de la enfermedad activa en el hombre. Sin embargo, algunos de los mecanismos moleculares implicados en la enfermedad osteoarticular han comenzado a dilucidarse recientemente. Brucella abortus induce daño óseo a través de diversos mecanismos en los cuales están implicados TNF-α y RANKL. En estos procesos participan células inflamatorias que incluyen monocitos/macrófagos, neutrófilos, linfocitos T del tipo Th17 y linfocitos B. Además, B. abortus puede afectar directamente las células osteoarticulares. La bacteria inhibe la deposición de la matriz ósea por los osteoblastos y modifica el fenotipo de estas células para producir metaloproteinasas de matriz (MMPs) y la secreción de citoquinas que contribuyen a la degradación del hueso. Por otro lado, la infección por B. abortus induce un aumento en la osteoclastogénesis, lo que aumenta la resorción de la matriz ósea orgánica y mineral y contribuye al daño óseo. Dado que la patología inducida por Brucella afecta el tejido articular, se estudió el efecto de la infección sobre los sinoviocitos. Estos estudios revelaron que, además de inducir la activación de estas células para secretar quemoquinas, citoquinas proinflamatorias y MMPs, la infección inhibe la muerte por apoptosis de los sinoviocitos. Brucella es una bacteria intracelular que se replica en el retículo endoplásmico de los macrófagos. El análisis de los sinoviocitos infectados con B. abortus indicó que las bacterias también se multiplican en el retículo endoplasmático, lo que sugiere que la bacteria podría usar este tipo celular para la multiplicación intracelular durante la localización osteoarticular de la enfermedad. Los hallazgos presentados en esta revisión intentan responder a preguntas sobre los mediadores inflamatorios implicados en el daño osteoarticular causado por Brucella. (AU)

Brucellosis is one of the most important zoonotic diseases that can produce chronic disease in humans worldwide. Osteoarticular involvement is the most common presentation of human active disease. The molecular mechanisms implicated in bone damage have started to be elucidated. B. abortus induces bone damage through diverse mechanisms in which TNF-α and RANKL are implicated. These processes are driven by inflammatory cells, including monocytes/macrophages, neutrophils, Th17 lymphocytes and B cells. Also, Brucella abortus (B. abortus) can directly affect osteoarticular cells. The bacterium inhibits bone matrix deposition by osteoblast and modifies the phenotype of these cells to produce matrix methalloproteinases (MMPs) and cytokine secretion that contribute to bone matrix degradation. B. abortus also affects osteoclast increasing mineral and organic bone matrix resorption and contributing to bone damage. Since the pathology induced by Brucella species involves joint tissue, experiments conducted in sinoviocytes revealed that besides inducing the activation of these cells to secrete chemokines, proinflammatory cytokines and MMPS, the infection also inhibits sinoviocyte apoptosis. Brucella is an intracellular bacterium that replicate in the endoplasmic reticulum of macrophages. The analysis of B. abortus infected sinoviocytes indicated that bacteria also replicate in their reticulum suggesting that the bacterium could use this cell type for intracellular replication during the osteoarticular localization of the disease. The findings presented in this review try to answer key questions about the inflammatory mediators involved in osteoarticular damage caused by Brucella. (AU)

Histologic assessment of extraction sockets following tooth extraction: suitability of a rabbit model

This study was aimed at determining the suitability of rabbits for assessment of alveolar bone healing following tooth extraction. Methods: Six (6) adult female New Zealand rabbits were used for this study. They were acclimatized under stand ard laboratory conditions for two weeks before the commencement of the study. Tooth extraction wascarried out in all the rabbits and this was followed by histologic assessment of alveolar bone healing and osteocyte count at week 2 and week 4 post extraction. Results: All the rabbits tolerated the extraction procedure and no complication was recorded. Histo-architecture of alveolar bone was characterized by marked osteoblastic activity at week 2 post extraction and increased osteocyte presence at week 4 post extraction. Average value of osteocyte count (cells/µm2) was 20 ± 4.58 at week 2 post extraction and 32.33 ± 2.08 at week 4 post extraction. Conclusion: The result obtained from this study shows that the rabbit could well serve as an experimental anima l for assessment of alveolar bone healing following tooth extraction

Mechanism of participation of osteocytes in the formation of osteoclasts under hypoxia / 华西口腔医学杂志

OBJECTIVE@#To investigate the mechanism of the participation of osteocytes in the formation of osteoclasts under hypoxia.@*METHODS@#The hypoxia culture system of osteocyte-like cell line MLO-Y4 was established by deferoxamine mesylate (DFO) in vitro. The proliferation of MLO-Y4 cells was examined by CCK-8 cell proliferation/toxicity assay. RAW264.7 cells were induced to osteoclasts by the conditioned medium containing the cultured MLO-Y4. Tartrate-resistant acid phosphatase (TRAP) staining was performed on day 7. Quantitative real-time fluorescence polymerase chain reaction, immunofluorescence, and Western blot were used to detect the expression levels of hypoxia-inducible factor (HIF)-1α and receptor activator of nuclear factor-κB ligand (RANKL) in MLO-Y4 under hypoxia. The effects of siHIF-1α on the expression levels of HIF-1α and RANKL in MLO-Y4 under the same conditions were detected.@*RESULTS@#DFO (100 μmol·L⁻¹) promoted the proliferation of MLO-Y4 at 24 h, which decreased with time (P<0.01). After the addition of soluble sRANKL, the formation of osteoclasts was significantly increased in the DFO group (P<0.001). The expression of RANKL mRNA in MLO-Y4 under 100 μmol·L⁻¹ DFO increased first and then decreased with the duration of hypoxia. This expression reached a peak at 24 h (P<0.01). Hypoxia up-regulated the expression of HIF-1α and RANKL protein (P<0.01). Under hypoxia, siHIF-1α downregulated the expression of HIF-1α and RANKL (P<0.01). siHIF-1α also decreased the number of osteoclasts (P<0.01).@*CONCLUSIONS@#Under hypoxia, MLO-Y4 could facilitate the formation of RANKL through upre-gulating the expression of HIF-1α protein, thereby accelerate the differentiation of RAW264.7 cells into osteoclasts.

Skeletal mineralization: mechanisms and diseases

Skeletal mineralization is initiated in matrix vesicles (MVs), the small extracellular vesicles derived from osteoblasts and chondrocytes. Calcium and inorganic phosphate (Pi) taken up by MVs form hydroxyapatite crystals, which propagate on collagen fibrils to mineralize the extracellular matrix. Insufficient calcium or phosphate impairs skeletal mineralization. Because active vitamin D is necessary for intestinal calcium absorption, vitamin D deficiency is a significant cause of rickets/osteomalacia. Chronic hypophosphatemia also results in rickets/osteomalacia. Excessive action of fibroblast growth factor 23 (FGF23), a key regulator of Pi metabolism, leads to renal Pi wasting and impairs vitamin D activation. X-linked hypophosphatemic rickets (XLH) is the most common form of hereditary FGF23-related hypophosphatemia, and enhanced FGF receptor (FGFR) signaling in osteocytes may be involved in the pathogenesis of this disease. Increased extracellular Pi triggers signal transduction via FGFR to regulate gene expression, implying a close relationship between Pi metabolism and FGFR. An anti-FGF23 antibody, burosumab, has recently been developed as a new treatment for XLH. In addition to various forms of rickets/osteomalacia, hypophosphatasia (HPP) is characterized by impaired skeletal mineralization. HPP is caused by inactivating mutations in tissue-nonspecific alkaline phosphatase, an enzyme rich in MVs. The recent development of enzyme replacement therapy using bone-targeting recombinant alkaline phosphatase has improved the prognosis, motor function, and quality of life in patients with HPP. This links impaired skeletal mineralization with various conditions, and unraveling its pathogenesis will lead to more precise diagnoses and effective treatments.

Correlation of spontaneous adipocyte generation with osteogenic differentiation of porcine skin-derived stem cells

The objective of this study was to examine effects of spontaneous adipocyte generation on osteogenic differentiation of porcine skin-derived stem cells (pSSCs). Correlation between osteogenic differentiation and adipocyte differentiation induced by osteocyte induction culture was determined using different cell lines. Osteogenic differentiation efficiency of pSSCs was then analyzed by controlling the expression of adipocyte-specific transcription factors during osteogenic induction culture. Among four cell lines, pSSCs-II had the lowest lipid droplet level but the highest calcium content (p < 0.05). It also expressed significantly low levels of peroxisome proliferator-activated receptor gamma 2 (PPARγ2) and adipocyte protein 2 (aP2) mRNAs but very high levels of runt-related transcription factor 2 (Runx2) and alkaline phosphatase (ALP) mRNAs as osteogenic makers (p < 0.05). Oil red O extraction was increased by 0.1 µM troglitazone (TGZ) treatment but decreased by 50 µM bisphenol A diglycidyl ether (BADGE) (p < 0.05). Calcium content was drastically increased after BADGE treatment compared to that in osteogenic induction control and TGZ-treated pSSCs (p < 0.05). Relative expression levels of PPARγ2 and aP2 mRNAs were increased by TGZ but decreased by BADGE. Expression levels of Rucx2 and ALP mRNAs, osteoblast-specific marker genes, were significantly increased by BADGE treatment (p < 0.05). The expression level of BCL2 like 1 was significantly higher in BADGE-treated pSSCs than that in TGZ-treated ones (p < 0.05). The results demonstrate that spontaneous adipocyte generation does not adversely affect osteogenic differentiation. However, reducing spontaneous adipocyte generation by inhibiting PPARγ2 mRNA expression can enhance in vitro osteogenic differentiation of pSSCs.

Linkage of Fibroblast Growth Factor 23 and Phosphate in Serum: Phosphate and Fibroblast Growth Factor 23 Reduction by Increasing Dose of Sevelamer

BACKGROUND: High serum phosphate and fibroblast growth factor-23 (FGF-23) levels are well-recognized independent risk factors of mortality and morbidity in patients with chronic kidney diseases (CKDs). Sevelamer, as a phosphate chelating agent, reduces serum phosphate and FGF-23 levels produced by bone osteocytes. This study aimed to determine the best dose at which sevelamer could successfully reduce serum phosphate and FGF-23 levels in rat models of adenine-induced CKD. METHODS: CKD was induced using adenine. Healthy and CKD-induced rats were divided into 6 groups as follows: healthy controls; CKD controls; rats treated with 1%, 2%, and 3% sevelamer for CKDs; and healthy rats administered 3% sevelamer. Biochemical factors and serum FGF-23 levels were measured using spectrophotometry and enzyme-linked immunosorbent assay methods. RESULTS: Serum phosphate levels were best decreased in rats receiving 3% sevelamer in their diet (5.91±1.48 mg/dL vs. 8.09±1.70 mg/dL, P < 0.05) compared with the CKD control rats. A dose-dependent decrease in serum FGF-23 levels was observed, and the most significant results were obtained in rats receiving 3% sevelamer compared with the CKD control rats (142.60±83.95 pg/mL vs. 297.15±131.10 pg/mL, P < 0.01). CONCLUSIONS: Higher sevelamer doses significantly reduced serum phosphate and FGF-23 levels in adenine-induced CKD rats.

Skeletal Fragility in Type 2 Diabetes Mellitus

Type 2 diabetes (T2D) is associated with an increased risk of fracture, which has been reported in several epidemiological studies. However, bone mineral density in T2D is increased and underestimates the fracture risk. Common risk factors for fracture do not fully explain the increased fracture risk observed in patients with T2D. We propose that the pathogenesis of increased fracture risk in T2D is due to low bone turnover caused by osteocyte dysfunction resulting in bone microcracks and fractures. Increased levels of sclerostin may mediate the low bone turnover and may be a novel marker of increased fracture risk, although further research is needed. An impaired incretin response in T2D may also affect bone turnover. Accumulation of advanced glycosylation endproducts may also impair bone strength. Concerning antidiabetic medication, the glitazones are detrimental to bone health and associated with increased fracture risk, and the sulphonylureas may increase fracture risk by causing hypoglycemia. So far, the results on the effect of other antidiabetics are ambiguous. No specific guideline for the management of bone disease in T2D is available and current evidence on the effects of antiosteoporotic medication in T2D is sparse. The aim of this review is to collate current evidence of the pathogenesis, detection and treatment of diabetic bone disease.

Evaluation of apoptosis and osteopontin expression in osteocytes exposed to orthodontic forces of different magnitudes

The in vivo response of osteocytes to different force magnitudes soon after they are applied remains to be elucidated. The aim of this study was to examine the early effects of applying a very light (LF: 0,16 N) and a very strong (SF: 2,26 N) orthodontic force during one hour on apoptosis and osteopontin (OPN) expression on alveolar bone osteocytes, in rats. Results: LF: compared to the control group, they showed a significant increase in OPN expression, and a significant decrease in the number of TUNELpositive osteocytes. SF: compared to the control group, they showed a significant increase in OPN expression and a significant decrease in the number of TUNELpositive osteocytes. Our results show that osteocytes respond very early to the application of tension and pressure forces of different magnitudes, and application of forces decreases the number of apoptotic osteocytes and increases OPN expression. These results allow concluding that osteocytes activate rapidly when subjected to locally applied forces, whether these forces be pressure or tension, light or strong forces. Grants: UBACyT 200201301002270 BA and School of Dentistry, University of Buenos Aires (AU)

Hasta el momento no se ha dilucidado la respuesta temprana in vivo de los osteocitos a la aplicación de fuerzas de diferentes magnitudes sobre el hueso. El objetivo de este estudio fue examinar la respuesta temprana de la aplicación de una fuerza ortodóncica muy liviana (FL: 0,16 N) y muy fuerte (FF: 2,26 N) durante una hora sobre la expresión de apoptosis y osteopontina (OPN) en los osteocitos del hueso alveolar, en ratas. Resultados: FL: en comparación con el grupo control, mostraron un aumento significativo en la expresión de OPN y una disminución significativa en el número de osteocitos TUNELpositivos. FF: en comparación con el grupo control, mostraron un aumento significativo en la expresión de OPN y una disminución signi ficativa en el número de osteocitos TUNELpositivos. Nuestros resultados muestran que los osteocitos responden muy temprano a la aplicación de fuerzas de tensión y presión de diferentes magnitudes, y la aplicación de fuerzas disminuye el número de osteocitos apoptóticos y aumenta la expresión de OPN. Estos resultados permiten concluir que los osteocitos se activan rápidamente cuando se los somete a fuerzas aplicadas localmente, ya sean estas fuerzas de presión o tensión, livianas o fuertes (AU)

Effects of the photobiomodulation using different energy densities on the periodontal tissues under orthodontic force in rats with type 2 diabetes mellitus

Abstract To evaluate the impact of the GaAlAs diode laser with energy densities of 160 J/cm2, 320 J/cm2, and 640 J/cm2 on the periodontal tissues under continuous orthodontic force application and on the rate of orthodontic tooth movement in rats with type-2 diabetes mellitus. The intensity of primary alveolar bone formation was also investigated through the immune-positive osteocytes for OPN antibody. Forty adult male Wistar rats were divided into eight groups of 5 rats: normoglycemic (N), 160 J-laser-normoglycemic (160 J-LN), 320 J-laser-normoglycemic (320 J-LN), 640 J-laser-normoglycemic (640 J-LN), diabetic (D), 160 J-laser-diabetic (160 J-LD), 320 J-laser-diabetic (320 J-LD), and 640 J-laser-diabetic (640 J-LD) rats. Diabetes mellitus was induced by a single intravenous injection of 40 mg/kg monohydrated-alloxan. An orthodontic force magnitude of 20cN was applied. The laser parameters were continuous emission of 780-nm wavelength, output power of 20mW, and fiber probe with a spot size of 0.04 cm in diameter. Radiographic, histomorphological, and immunohistochemical analysis were performed after a period of 21 days. The photobiomodulation using the energy density of 640 J/cm2 strongly stimulated the alveolar bone formation and contributed the reorganization of the soft periodontal tissues, followed by the 320 J/cm2. Extensive alveolar bone loss, intense infiltration of inflammatory cells, and degradation of the PDJ tissue were mainly found in the D and 160 J-LD groups. The rate of orthodontic tooth movement was represented by the interdental distance between the cementoenamel junctions of the right mandibular first and second molars . This distance was larger in the diabetic groups (D: 39.98±1.97, 160 J-LD: 34.84±6.01, 320 J-LD: 29.82±1.73, and 640 J-LD: 35.47±4.56) than in the normoglycemic groups (N: 21.13±1.19; 160 J-LN: 22.69±0.72, 320 J-LN: 22.28±0.78, and 640 J-LN: 24.56±2.11). The number of osteopontin-positive osteocytes was significantly greater in the 640 J-LD (14.72 ± 0.82; p < 0.01) and 640 J-LN (13.62 ± 1.33; p < 0.05) groups than with D (9.82 ± 1.17) and 160 J-LD (9.77 ± 1.10) groups. Therefore, the energy density of 640 J/cm2 provided the best maintenance and integrity of the periodontal tissue microarchitecture under continuous orthodontic force when compared with the other dosages, mainly in the uncontrolled diabetic rats. The interdental distance was greater in the D and 160 J-LD groups due to presence of severe periodontitis caused by diabetes plus the mechanical stress generated by continuous orthodontic forces, implying, thus, an insufficient biostimulatory effect for the dosage of 160 J/cm2.

Predicting the Role of Osteal Macrophages and Osteocytes in Bone Tissue Network Using a Mathematical Modeling / 치위생과학회지

The aim of this study was to investigate the role of osteal macrophages (osteomac) and osteocytes in bone remodeling using a mathematical model. We constructed the bone system with pre-osteoblasts, osteoclasts, osteocytes, and osteomac. Each link of the parameters and ordinary differential equations followed the Graham's model in 2013 except for the parameters of osteomac signaling and osteocytes signaling to link preosteoblasts and osteoblasts. We simulated the changes in each cell and bone volume according to the changes in the parameters of osteomac signaling and osteocytes signaling. The results showed bone volume was unstable and decreased gradually when the effectiveness of osteocytes and osteomac dropped below a certain level. When the parameters of osteomac signaling and osteocytes signaling to link preosteoblasts and osteoblasts had a value less than 1, bone volume increased with the increase in the parameter of osteomac signaling to link preosteoblasts and osteoblasts. Moreover, although the parameter of osteocytes signaling to link preosteoblasts and osteoblasts, increased in case of a small parameter of osteomac signaling, bone volulme decreased. If the parameters of osteomac signaling to link preosteoblasts and osteoblasts were over a certain level, bone volume was positively maintained, despite the parameter of osteocyte signaling to link preosteoblasts and osteoblasts. We suggested the osteomac may affect bone remodeling and may play an important role in bone cell network.

TCP wear particles causes injury of periprosthetic osteocytes in the mouse calvaria / 中国应用生理学杂志

OBJECTIVE@#To study whether tricalcium phosphate(TCP) wear particles cause injuries of periprosthetic osteocytes in the mouse calvaria, and to explain its molecular mechanism.@*METHODS@#Thirty six-week(ICR)male mice were randomly divided into sham group, model (TCP) group and 3-methyladenine (3-MA) group. A murine calvarial model of osteolysis was established by 30 mg of TCP wear particles implantation over the periosteum around the middle suture of calvaria in mice. On the second postoperative day, the autophagy specific inhibitor 3-MA (1.0 mg/kg) was subcutaneously injected to the calvaria in the 3-MA-treated mice every other day. After 2 weeks, blood and the calvaria were obtained. Micro-CT was used to detect bone mineral density(BMD), bone volume fraction (BVF) and porosity number. HE staining and flow cytometry were performed to analyze the viability and apoptosis of periprosthetic osteocytes. The serum levels of dentin matrix protein 1(DMP-1) and sclerostin (SOST) were determined by ELISA. The proteins expressions of DMP-1, SOST, Beclin-1 and microtuble-associated protein 1 light chain 3 (LC-3) were detected by Western blot in the calvaria osteocytes.@*RESULTS@#Compared with the sham group, the mice in the TCP group showed that a significant decrease in the viability of periprosthetic osteocytes, but obvious increases in number of osteocytes death and osteocytes apoptosis (<0.05), and in serum level and protein expression of SOST; significant decreases in serum level and protein expression of DMP-1 (<0.05), and remarkable up-regulation of autophagy-related factors beclin-1 and the conversion of LC3-Ⅱ from LC3-I in the calvaria osteocytes. Compared with TCP group, the mice in the 3-MA group showed that injuries of calvaria osteocytes were obviously aggravated, and osteocytes apoptosis was significantly increased (<0.05).@*CONCLUSIONS@#TCP wear particles can cause injuries of periprosthetic osteocytes via activation of apoptosis and autophagy, which promotes osteolysis around the prosthesis osteolysis and joint aseptic loosening.

Osteocyte morphology and orientation in relation to strain in the jaw bone / 国际口腔科学杂志·英文版

Bone mass is important for dental implant success and is regulated by mechanoresponsive osteocytes. We aimed to investigate the relationship between the levels and orientation of tensile strain and morphology and orientation of osteocytes at different dental implant positions in the maxillary bone. Bone biopsies were retrieved from eight patients who underwent maxillary sinus-floor elevation with β-tricalcium phosphate prior to implant placement. Gap versus free-ending locations were compared using 1) a three-dimensional finite-element model of the maxilla to predict the tensile strain magnitude and direction and 2) histology and histomorphometric analyses. The finite-element model predicted larger, differently directed tensile strains in the gap versus free-ending locations. The mean percentage of mineralised residual native-tissue volume, osteocyte number (mean ± standard deviations: 97 ± 40/region-of-interest), and osteocyte shape (~90% elongated, ~10% round) were similar for both locations. However, the osteocyte surface area was 1.5-times larger in the gap than in the free-ending locations, and the elongated osteocytes in these locations were more cranially caudally oriented. In conclusion, significant differences in the osteocyte surface area and orientation seem to exist locally in the maxillary bone, which may be related to the tensile strain magnitude and orientation. This might reflect local differences in the osteocyte mechanosensitivity and bone quality, suggesting differences in dental implant success based on the location in the maxilla.