Exosomes derived from M2 macrophages prevent steroid-induced osteonecrosis of the femoral head by modulating inflammation, promoting bone formation and inhibiting bone resorption.

Inflammatory reactions are involved in the development of steroid-induced osteonecrosis of the femoral head(ONFH). Studies have explored the therapeutic efficacy of inhibiting inflammatory reactions in steroid-induced ONFH and revealed that inhibiting inflammation may be a new strategy for preventing the development of steroid-induced ONFH. Exosomes derived from M2 macrophages(M2-Exos) display anti-inflammatory properties. This study aimed to examine the preventive effect of M2-Exos on early-stage steroid-induced ONFH and explore the underlying mechanisms involved. In vitro, we explored the effect of M2-Exos on the proliferation and osteogenic differentiation of bone marrow-derived mesenchymal stem cells(BMMSCs). In vivo, we investigated the role of M2-Exos on inflammation, osteoclastogenesis, osteogenesis and angiogenesis in an early-stage rat model of steroid-induced ONFH. We found that M2-Exos promoted the proliferation and osteogenic differentiation of BMMSCs. Additionally, M2-Exos effectively attenuated the osteonecrotic changes, inhibited the expression of proinflammatory mediators, promoted osteogenesis and angiogenesis, reduced osteoclastogenesis, and regulated the polarization of M1/M2 macrophages in steroid-induced ONFH. Taken together, our data suggest that M2-Exos are effective at preventing steroid-induced ONFH. These findings may be helpful for providing a potential strategy to prevent the development of steroid-induced ONFH.

Anti-sclerostin antibody therapy prevents post-ischemic osteonecrosis bone collapse via interleukin-6 association.

Osteonecrosis of the femoral head (ONFH) is a debilitating condition characterized by subchondral bone necrosis, which frequently culminates in joint destruction. Although total hip arthroplasty is conventionally practiced to remediate ONFH, for patients under the age of 60, the outcomes can be suboptimal. Chronic inflammation, particularly that mediated by interleukin-6 (IL-6), has been conjectured to be a potential mechanism underlying the etiology of ONFH. This study aimed at exploring the interplay between IL-6, the canonical Wnt signaling pathway, and ONFH to provide insights for potential therapeutic interventions. Human ONFH specimens depicted an elevation in ß-catenin expression in the transitional layer, while IL-6 levels were pronounced in the same region. Subsequently, mouse models of ischemic osteonecrosis were treated with an anti-sclerostin antibody to assess its effects on bone metabolism and cellular processes. Histological analysis revealed that the administration of anti-sclerostin antibodies effectuated early recovery from bone necrosis, reduced empty lacunae, and suppressed IL-6 expression. The treatment evidently initiated the activation of the Wnt/ß-catenin signaling pathway, presenting a potential mechanism associated with IL-6-mediated inflammation. Furthermore, the antibody upregulated osteoblast formation, downregulated osteoclast formation, and increased bone volume. Micro-CT imaging demonstrated increased bone volume, prevented epiphyseal deformity, and improved compression strength. Therefore, this study yields significant findings, indicating the potency of anti-sclerostin antibodies in effectively modulating the Wnt/ß-catenin pathway, associating with IL-6 expression, and preventing post-ONFH bone collapse. Additionally, this preclinical investigation in mouse models offers an avenue for prospective research on potential therapeutic interventions against human ONFH.

Oral health, dental treatment, and medication related osteonecrosis of the jaw in multiple myeloma - a longitudinal cohort study.

OBJECTIVE: The objective of the present study was to investigate oral health status, oral health related quality of life, and identify risk factors associated with invasive dental treatment and medication related osteonecrosis of the jaw in patients with multiple myeloma. MATERIAL AND METHODS: Patients newly diagnosed with multiple myeloma (n = 144) referred between January 2015 and September 2022 were retrospectively included. The patients underwent a thorough clinical and radiological oral examination and odontogenic infections were treated before the start of bisphosphonate treatment. The patients were followed annually, including clinical and radiological examinations. The oral health related quality of life was investigated by the OHIP-14 questionnaire. RESULTS: Dental treatment (RR = 7.75), receiving combination antineoplastic therapy≥3 (RR =4.13), periodontitis (RR = 4.21), and reduced number of teeth (RR = 2.87) were associated with an increased risk of medication related osteonecrosis of the jaw. The response rate of the OHIP-14 questionnaire was 70.2%. Oral pain or discomfort in the mouth related to the medical treatment was reported by 30.5%. CONCLUSION: Dental screening and treatment planning in patients with Multiple Myeloma may result in fewer oral infections and fewer interruptions of the medical treatment of myeloma.

Cyasterone has a protective effect on steroid-induced Osteonecrosis of the femoral head.

CONTEXT: Cyasterone alleviated the apoptosis of BMSCs induced by Dexamethasone via the PI3K/AKT signaling pathway. In addition, Cyasterone had a protective effect on SIONFH model rats by reducing the percentage of empty bone lacunae. OBJECTIVE: To study the effect of Cyasterone on apoptosis of rat BMSCs and its function on the SIONFH rat model. METHODS: Rat BMSCs were cultured and divided into Control, DXM and Cyasterone (DXM+Cyasterone) groups. The apoptosis of each group was detected by flow cytometry, the expressions of Caspase-3 and Caspase-9 were detected by immunofluorescence staining, and the mRNA and protein expressions of AKT, BAX, P53, P85, Bcl-2 and Cytochrome C were detected by qPCR and WB. In animal experiments, the femoral head of rats were subjected to HE staining and Micro-CT to observe the necrosis and repair conditions. RESULTS: The apoptosis rate of DXM and Cyasterone groups increased compared with Control group, and the apoptosis rate of Cyasterone group decreased compared with DXM group. Compared with DXM group, the mRNA expression of BAX, P53, P85 and Cytochrome C in Cyasterone group were increased, while the protein expression of AKT and Bcl-2 decreased. The histopathological and morphological analysis showed that Cyasterone promoted the trabecular bone structure in rat, which evenly benefit for the repair of SIONFH. CONCLUSION: Cyasterone can reduce the apoptosis of rat BMSCs induced by Dexamethasone, and help promoting the bone repair in SIONFH rats.

Preventive effect of teriparatide on medication-related osteonecrosis of the jaw in rats.

This study aimed to investigate the preventive effect of teriparatide (TPD) administration on medication-related osteonecrosis of the jaw (MRONJ) before tooth extraction due to periodontal lesions in bilaterally ovariectomized female rats treated with zoledronic acid. Thirty skeletally mature Sprague-Dawley rats were randomly divided into three groups: control (CONT, n = 10), zoledronic acid (ZA, n = 10), and zoledronic acid and teriparatide (ZA-TPD, n = 10). The rats were sacrificed 8 weeks after tooth extraction. Micro-computed tomography analysis of the tibia showed that bone mineral density was highest in the CONT, followed by that in the ZA and ZA-TPD groups (CONT/ZA, p = 0.009; CONT/ZA-TPD, p < 0.001; ZA/ZA-TPD, p < 0.001). In the trabecular bone analysis of the extraction site, significant differences in specific bone surface (CONT/ZA, p = 0.010; CONT/ZA-TPD, p = 0.007; ZA/ZA-TPD, p = 0.002) and trabecular thickness (CONT/ZA-TPD, p = 0.002; ZA/ZA-TPD, p = 0.002) were observed. Histological analyses of the extraction sites revealed characteristic MRONJ lesions in the ZA group. Osteonecrosis, inflammatory cells, and sequestrum were less frequently observed in the ZA-TPD group than in the ZA group. In conclusion, TPD administration before tooth extraction helped reduce the occurrence of MRONJ in rats treated with zoledronic acid, confirming its preventative effects.

The prophylactic effects of naringin on steroid-induced early-stage osteonecrosis in rats: a preliminary study.

The excessive steroid may cause dyslipidaemia and oxidative insult during femoral head osteonecrosis, inducing bone loss and impairment of the intraosseous blood system. In contrast, bio-flavanone naringin has shown antioxidant, antiresorptive and lipid-lowering bioactivities. The present research is an effort to explore the anti-ON potential of naringin in vivo and in vitro. After a 6-week treatment, the femora were dissected for histological examination following bone mineral density assay by X-ray absorptiometry. Blood samples were examined for coagulation, oxidative stress, lipid transportation and endothelial injury. Marrow samples were cultured and assayed for adipogenic and osteogenic alterations by ALP activity, mineralization, RT-qPCR and western blot analysis. The results showed that naringin exerted a dose-dependent effect on reducing ON incidence, with inhibition of osteoporosis, oxidative stress and dyslipidaemia. The mechanism included the suppression of PPARγ2 for adipogenesis of bone marrow stem cells (BMSCs) and the prevention of oxidative stress in endothelium injury. Naringin may restore steroid-impaired osteogenesis by enhancing the mRNA and protein expression of osteogenic markers in a dose-ascending manner and new bone formation can be found in naringin groups. Taken together, our findings showed that naringin may serve as a prophylactic agent and selective PPARγ modulator for the early-stage ON.

Kienböck's disease: preventing disease progression in early-stage disease.

Currently Kienböck's disease remains an 'unsolved' problem in hand surgery. Different factors have been associated with the avascular necrosis of the lunate. Mechanical, vascular and biological factors, alone or in combination, may have an influence in the aetiopathogenesis and determine the progress of the disease and even the results of the treatment. This is especially relevant in the early stages, in which conservative or surgical treatment may modify the natural history of the disease, maintaining the lunate structure and thus preserving the joint surfaces. There are multiple surgical treatments for Kienböck's disease in the early stages, before lunate collapse; each one is based on one of the possible factors that can cause avascular necrosis of the lunate. The objective is not only to treat symptoms but to prevent progression. This article is a review of the most frequent treatments used in the early stages and a personal view of the authors.Level of evidence: V.

[Protective effect of Kaempferol on endothelial cell injury in glucocorticoid induced osteonecrosis of the femoral head].

Objective: To explore the effect of Kaempferol on bone microvascular endothelial cells (BMECs) in glucocorticoid induced osteonecrosis of the femoral head (GIONFH) in vitro. Methods: BMECs were isolated from cancellous bone of femoral head or femoral neck donated voluntarily by patients with femoral neck fracture. BMECs were identified by von Willebrand factor and CD31 immunofluorescence staining and tube formation assay. The cell counting kit 8 (CCK-8) assay was used to screen the optimal concentration and the time point of dexamethasone (Dex) to inhibit the cell activity and the optimal concentration of Kaempferol to improve the inhibition of Dex. Then the BMECs were divided into 4 groups, namely, the cell group (group A), the cells treated with optimal concentration of Dex group (group B), the cells treated with optimal concentration of Dex+1 µmol/L Kaempferol group (group C), and the cells treated with optimal concentration of Dex+5 µmol/L Kaempferol group (group D). EdU assay, in vitro tube formation assay, TUNEL staining assay, Annexin Ⅴ/propidium iodide (PI) staining assay, Transwell migration assay, scratch healing assay, and Western blot assay were used to detect the effect of Kaempferol on the proliferation, tube formation, apoptosis, migration, and protein expression of BMECs treated with Dex. Results: The cultured cells were identified as BMECs. CCK-8 assay showed that the optimal concentration and the time point of Dex to inhibit cell activity was 300 µmol/L for 24 hours, and the optimal concentration of Kaempferol to improve the inhibitory activity of Dex was 1 µmol/L. EdU and tube formation assays showed that the cell proliferation rate, tube length, and number of branch points were significantly lower in groups B-D than in group A, and in groups B and D than in group C ( P<0.05). TUNEL and Annexin V/PI staining assays showed that the rates of TUNEL positive cells and apoptotic cells were significantly higher in groups B-D than in group A, and in groups B and D than in group C ( P<0.05). Scratch healing assay and Transwell migration assay showed that the scratch healing rate and the number of migration cells were significantly lower in groups B-D than in group A, and in groups B and D than in group C ( P<0.05). Western blot assay demonstrated that the relative expressions of Cleaved Caspase-3 and Bax proteins were significantly higher in groups B-D than in group A, and in groups B and D than in group C ( P<0.05); the relative expressions of matrix metalloproteinase 2, Cyclin D1, Cyclin E1, VEGFA, and Bcl2 proteins were significantly lower in groups B-D than in group A, and in groups B and D than in group C ( P<0.05). Conclusion: Kaempferol can alleviate the damage and dysfunction of BMECs in GIONFH.

Denosumabe e osteonecrose dos maxilares: o que o cirugião-dentista precisa saber? / Denosumab and osteonecrosis of the jaws: what does the dental surgeon need to know? / Denosumab y osteonecrosis de mandíbulas: ¿qué necesita saber el cirujano dental?

Introdução:O Denosumabeé um fármaco antirreabsortivo indicado para o tratamento de osteoporose e doenças ósseas metastáticas. O seu uso está associado ao desenvolvimento de reações adversas em diferentes órgãos, como a osteonecrose dos maxilares, que é o evento adverso de interesseodontológico. Objetivo:Realizar um levantamento bibliográfico sobre o mecanismo de ação do Denosumabe no tecido ósseo e destacar a importância do cirurgião-dentista na prevenção, no diagnóstico e tratamento da osteonecrose nos maxilares.Metodologia:Trata-se de uma revisão integrativa elaboradaem duas etapas: inicialmente realizou-se uma busca de artigos publicados entre os anos 2010a 2022, sobre a osteonecrose em pacientes que fazem uso do Denosumabe nas plataformas de dados Pubmed, ScieloeBiblioteca Virtual em Saúde. Posteriormente, foi feita uma seleção de partes relevantes para a pesquisa, uma leitura analítica e a organização das informações coletadas pertinentes a cada tópico da pesquisa.Resultados:ODenosumabe inibea ligação da citocina RANKL ao seu receptor RANK, tal mecanismo de ação reduz o processo de reabsorção óssea execessiva. As osteonecroses podem apresentar-se em diferentes níveis de estadiamento e caracterizam-se como área de exposição óssea necrótica na região maxilofacial, permanecendo por mais de oito semanas e sem histórico de radioterapia ou doença metastática evidentes nos maxilares. Alguns fatores predispõem o desenvolvimento das osteonecroses, entre eles: procedimentos odontológicos cirúrgicos. Ainda não existe um protocolo de tratamento definitivo, entretanto, modalidades terapêuticas coadjuvantes são administradas de acordo com a condição clínicado paciente.Conclusões:O exame clínico deve ser minucioso, atentando-se a qualquer alteração na cavidade bucal, às doenças preexistentes e às medicações utilizadas pelo paciente. Em todos os casos deve-se, realizar orientações de higiene oral e adequação do meio bucal previamente ao tratamento oncológico e ao uso de drogas antirreabsortivas (AU).

Introduction:Denosumab is an antiresorptive drug indicated for the treatment of osteoporosis and metastatic bone diseases. Its use is associated with the development of adverse reactions in different organs, such as osteonecrosis of the jaws, which is an adverse event ofdentalinterest.Objective:Conducta bibliographic survey on the mechanism of action of Denosumab in bone tissue and to highlight the importance of the dentist in the prevention, diagnosis and treatment of osteonecrosis in the jaws. Methodology: This is an integrative review carried out in two stages: initially, a search was carried out for articles published between the years 2010to 2022, on osteonecrosis in patients using Denosumab in the data platforms Pubmed, Scieloand Virtual Health Library(BVS). Subsequently, a selection of relevant parts for the research was made, an analytical reading and the organization of the collected information pertinent to each research theme was carried out.Results:TheDenosumab inhibitsthe binding of the RANKL cytokine to its RANK receptor, this mechanism of action reduces the process of excessive bone resorption. Osteonecrosis can present at different staging levels and are characterized as an area of necrotic bone exposure in the maxillofacial region, lasting for more than eight weeks and without a history of radiotherapy or evident metastatic disease in the jaws. Some factors predispose the development of osteonecrosis, including: surgical dental procedures. There is still no definitive treatment protocol, however, supporting therapeutic modalities are administered according to the patient's clinical condition.Conclusions:The clinical examination must be thorough, paying attention to any changes in the oral cavity, pre existing diseases and medications used by the patient. In all cases, guidelines on oral hygiene and adequacy of the oral environment should be carried out prior to oncological treatment and the use of antiresorptive drugs (AU).

Introducción: Denosumab es un fármaco antirresortivo indicado para el tratamiento de la osteoporosis y enfermedades óseas metastásicas. Su usoestá asociado al desarrollo de reacciones adversas en diferentes órganos, comola osteonecrosis de los maxilares, que es un evento adverso de interés odontológico. Objetivo: Realizar un levantamiento bibliográfico sobre el mecanismo de acción de Denosumab en el tejido óseo y resaltar la importancia del odontólogo en la prevención, diagnóstico y tratamiento de la osteonecrosis en los maxilares. Metodología: Esta es una revisión integradora realizada en dos etapas: inicialmente se realizó una búsqueda de artículos publicados entre los años 2010 a 2022, sobre osteonecrosis en pacientes usuarios de Denosumab en las plataformas Pubmed, ScieloyBiblioteca Virtual en Salud(BVS).Posteriormente, se realizó una selección de partes relevantes para la investigación, se realizó una lectura analítica y la organización de la información recolectada relevante para cada tema de investigación. Resultados:Denosumab inhibela unión de la citoquina RANKL a su receptor RANK, este mecanismo de acción reduce el proceso de reabsorción ósea excesiva. La osteonecrosis puede presentarse en diferentes nivelesde estadificación y se caracterizan por un área de exposición ósea necrótica en la región maxilofacial, con una duración mayor a ocho semanas y sin antecedentes de radioterapia o enfermedad metastásica evidente en los maxilares. Algunos factores predisponen al desarrollo de osteonecrosis, entre ellos: procedimientos quirúrgicos dentales. Aún noexiste un protocolo de tratamiento definitivo, sin embargo, se administran modalidades terapéuticas de apoyo de acuerdo a la condición clínica del paciente.Conclusiones: El examen clínico debe ser minucioso, prestando atención a cualquier cambio en la cavidad bucal, enfermedades preexistentes y medicamentos utilizados por el paciente. En todos los casos se deben realizar pautas de higiene bucal y adecuación del medio bucal previo al tratamiento oncológico y al uso de fármacos antirresortivos (AU).

Bisphosphonates: how to proceed in orthodontics / Bisphosphonates : conduite à tenir en orthodontie

Introduction: Bisphosphonates are mainly used in the treatment of osteoporosis and in oncology. They bind to bone and inhibit the action of osteoclasts, leading to a decrease in bone remodeling and thus hindering tooth movement. The main objective was to present, through a review of the literature, the indications and therapeutic modalities for orthodontic treatment of patients who are or have been treated with bisphosphonates. The second objective was to propose a decisional organization chart for medical care. Materials and Methods: The search was done by keywords on PubMed. Results: 189 articles were found, mostly case reports. 1) Intravenous treatment is a contraindication to ODF treatment. 2) Per os treatment is possible with precautions: to be in accordance with the prescribing practitioner, avoid major travels, avoid surgical procedures (extractions...) which must be as atraumatic as possible. A delay in healing is to be expected. The benefit-risk ratio must be taken into account. The risks - the patient must be informed of them - are slowed movement and osteonecrosis. Clinical and radiological follow-up is necessary and may warrant re-evaluation of treatment at any time: excessive tooth mobility, molar furcation damage, unusually persistent periodontal pain and symptoms, fistulas, exposed areas of necrotic bone. Discussion: The articles are of low grade. Most of the articles are studies made on animals. Conclusion: Research is ongoing to evaluate the value of bisphosphonates as anchorage reinforcement.

Introduction: Indiqués essentiellement dans le traitement de l'ostéoporose et en oncologie, les bisphosphonates se lient à l'os et inhibent l'action des ostéoclastes, entraînent une diminution du remodelage osseux et inhibent donc le déplacement dentaire. L'objectif principal de cet article était de présenter, via une revue de littérature, les indications et les modalités thérapeutiques orthodontiques pour les patients sous ou ayant été sous bisphosphonates. L'objectif secondaire était de proposer un organigramme décisionnel de prise en charge. Matériels et méthodes: La recherche a été faite par mots-clés sur PubMed. Résultats: Au total, 189 articles ont été trouvés, majoritairement des rapports de cas. On peut en déduire : 1) Un traitement par voie intraveineuse en cours est une contre-indication au traitement ODF. 2) En per os, le traitement est possible avec des précautions : se mettre d'accord avec le médecin prescripteur, éviter les gros déplacements, éviter les gestes chirurgicaux (avulsions…) qui doivent être le plus atraumatiques possibles. Un retard de cicatrisation est à prévoir. Le rapport bénéfice/risque doit être pesé. Les risques ­ dont le patient doit être informé ­ sont le ralentissement de déplacement et l'ostéonécrose. Un suivi clinique et radiologique est nécessaire et peut justifier à tout moment une réévaluation du traitement : mobilité excessive des dents, atteinte de la furcation des molaires, douleurs et symptômes parodontaux inhabituellement persistants, fistules, zones exposées d'os nécrotique. Discussion: Les articles sont de faible grade. La majorité des articles sont des études sur l'animal. Conclusion: Des recherches sont en cours pour évaluer l'intérêt des bisphosphonates en renfort d'ancrage.

Decrease in dysbaric osteonecrosis severity as a result of 45-minute oxygen pre-breathe.

Sudden decompression can result in bubble formation as the result of nitrogen gas (N2) dissolved in tissue during disabled submarine escape (DISSUB). This may cause dysbaric osteonecrosis (DON), a condition in long bones where bubbles in fatty marrow result in ischemia and necrosis. Previous research has shown that oxygen (O2) pre-breathe of two hours resulted in a reduction of DON; however, effects of shorter O2 pre-breathe remain uncertain. This study's aim was to understand the effect of shorter lengths of O2 pre-breathe. Eight adult Suffolk ewes (89.5± 11.5 kg) were exposed to 33 feet of seawater (fsw) for 24 hours. They were placed randomly into four groups and exposed to either 45, 30 or 15 minutes of O2 (91-88%) pre-breathe; the controls received none. They were then rapidly decompressed. Alizarin complexone was later injected intravenously to visualize the extent of DON in the right and left long bones (radii, tibiae, femur and humeri). The 30- and 15-minute pre-breathe groups saw the greatest deposition. There was significant decrease of variance in the 45-minute group when compared with all other treatments, suggesting that 45 minutes of O2 pre-breathe is required to effectively increase confidence in the reduction of DON. Similar confidence was not reflected in the 30-minute and 15-minute groups: 45 minutes of pre-breathe was the minimum amount needed to effectively prevent against DON in DISSUB escape at 33 fsw. However, future research is needed to determine how to calculate effective dosages of O2 pre-breathe to prevent DON in any given scenario.

Osteonecrosis of the jaw: a rare but possible side effect in thyroid cancer patients treated with tyrosine-kinase inhibitors and bisphosphonates.

Osteonecrosis of the jaw (ONJ) is a rare but very serious disease that can affect both jaws. It is defined as exposed bone in the maxillofacial region that does not heal within 8 weeks after a health care provider identification. ONJ can occur spontaneously or can be due to drugs like bisphosphonates (BPS) and anti-RANK agents, in patients with no history of external radiation therapy in the craniofacial region. Although in phase 3 trials of tyrosine kinase inhibitors (TKIs) used in thyroid cancer (TC) the ONJ was not reported among the most common side effects, several papers reported the association between ONJ and TKIs, both when they are used alone and in combination with a bisphosphonate. The appearance of an ONJ in a patient with metastatic radio-iodine refractory differentiated TC, treated with zoledronic acid and sorafenib, has put us in front of an important clinical challenge: when a ONJ occurred during TKIs treatment, it really worsens the patients' quality of life. We should consider that in the case of ONJ a TKI discontinuation becomes necessary, and this could lead to a progression of neoplastic disease. The most important aim of this review is to aware the endocrinologists/oncologists dealing with TC to pay attention to this possible side effect of BPS and TKIs, especially when they are used in association. To significantly reduced the risk of ONJ, both preventive measures before initiating not only antiresorptive therapy but also antiangiogenic agents, and regular dental examinations during the treatment should always be proposed.

Inhibition of MAGL activates the Keap1/Nrf2 pathway to attenuate glucocorticoid-induced osteonecrosis of the femoral head.

Glucocorticoids (GCs) are used in treating viral infections, acute spinal cord injury, autoimmune diseases, and shock. Several patients develop GC-induced osteonecrosis of the femoral head (ONFH). However, the pathogenic mechanisms underlying GC-induced ONFH remain poorly understood. GC-directed bone marrow mesenchymal stem cells (BMSCs) fate is an important factor that determines GC-induced ONFH. At high concentrations, GCs induce BMSC apoptosis by promoting oxidative stress. In the present study, we aimed to elucidate the molecular mechanisms that relieve GC-induced oxidative stress in BMSCs, which would be vital for treating ONFH. The endocannabinoid system regulates oxidative stress in multiple organs. Here, we found that monoacylglycerol lipase (MAGL), a key molecule in the endocannabinoid system, was significantly upregulated during GC treatment in osteoblasts both in vitro and in vivo. MAGL expression was positively correlated with expression of the NADPH oxidase family and apoptosis-related proteins. Functional analysis showed that MAGL inhibition markedly reduced oxidative stress and partially rescued BMSC apoptosis. Additionally, in vivo studies indicated that MAGL inhibition effectively attenuated GC-induced ONFH. Pathway analysis showed that MAGL inhibition regulated oxidative stress in BMSCs via the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. The expression of Nrf2, a major regulator of intracellular antioxidants, was upregulated by inhibiting MAGL. Nrf2 activation can mimic the effect of MAGL inhibition and significantly reduce GC-induced oxidative damage in BMSCs. The beneficial effects of MAGL inhibition were attenuated after the blockade of the Keap1/Nrf2 antioxidant signaling pathway. Notably, pharmacological blockade of MAGL conferred femoral head protection in GC-induced ONFH, even after oxidative stress responses were initiated. Therefore, MAGL may represent a novel target for the prevention and treatment of GC-induced ONFH.

Effects of zoledronic acid on osteonecrosis and acute lymphoblastic leukemia treatment efficacy in preclinical models.

BACKGROUND: Osteonecrosis is a devastating side effect of acute lymphoblastic leukemia (ALL) therapy. Associations between bone density loss and osteonecrosis have sparked interest in using bisphosphonates to reduce this complication. PROCEDURE: We assessed the impact of zoledronic acid (ZA) on the development of osteonecrosis in murine models when used either throughout therapy (continuous administration) or late in therapy after vascular lesions have developed but before osteonecrosis has occurred. Effects on bone density were measured using microcomputed tomography (µCT)-assessed tibial cortical thickness, while osteonecrosis was assessed histologically in the distal femur. Effects on antileukemic efficacy of chemotherapy were evaluated in both immunocompetent/syngeneic and patient-derived xenograft (PDX) models. RESULTS: Continuous administration of ZA with chemotherapy prevented chemotherapy-associated bone loss (p < .001) and reduced osteonecrosis (p = .048). Late initiation of ZA diminished bone loss (p < .001) but had no impact on the development of osteonecrosis (p = .93). In the immunocompetent murine ALL model, mice treated with ZA and chemotherapy succumbed to leukemia sooner than mice treated with chemotherapy alone (p = .046). Analysis using PDX showed a nonsignificant decrease in survival with ZA (p = .17). CONCLUSION: Our data indicate ZA may prevent osteonecrosis if begun with chemotherapy but showed no benefit when administered later in therapy. However, ZA may also reduce the antileukemic efficacy of chemotherapy.

Proposal for a preventive protocol for medication-related osteonecrosis of the jaw / Propuesta de protocolo preventivo para la osteonecrosis de la mandíbula relacionada con medicamentos

Background: Medication-related osteonecrosis of the jaw (MRONJ) is a severe adverse reaction experienced by somepatients exposed to certain drugs (antiresorptives such as bisphosphonates or denosumab, and antiangiogenic drugs).From a review of the literature it appears that there is no uniform criterion when selecting preventive measures;these vary according to author. Likewise, the measures recommended are usually general, so that in few cases theyresult in specific actions to be applied depending on the different variables involved such as the type of drug used,the duration of its application, the underlying pathology, the presence or absence of risk factors, etc. The aim of thisstudy has been to design a preventive protocol which can be easily applied in any clinic or by any dental care service.Material and Methods: We undertook an exhaustive literature review to find any articles related to the topic of study,namely, preventive measures for medication-related osteonecrosis of the jaw, on the one hand generically and on theother focusing on dental implant treatment. The most part the criteria of the Preferred Reporting Items for SystematicReviews and Meta-Analyses (PRISMA) guidelines were followed. From 3946 items, we selected a total of 21 items.Results: From the analysis of the selected articles, several protocols have been developed that are easy to applyin a dental clinic.: Protocol 1. Before starting treatment with antiresorptives (Patients who are going to be treatedfor osteoporosis / Patients who are going to be treated for cancer). Protocol 2. Once treatment is initiated withantiresorptives (Patients being treated for osteoporosis / Patients being treated for cancer)...(AU)

C-Nail versus plate osteosynthesis in displaced intra-articular calcaneal fractures-a comparative retrospective study.

BACKGROUND: Locking plate osteosynthesis via an L-shaped lateral approach is the gold standard in treating displaced intra-articular calcaneal fractures. High complication rates are known for this approach. The most frequent complications are wound edge necrosis and superficial wound infections. To reduce complication rates, a locking intramedullary nail (C-Nail) was developed that can be implanted minimally invasively via a sinus tarsi approach. We compared the postoperative complication rate and the outcome of plate osteosynthesis versus C-Nail in displaced intra-articular calcaneal fractures. METHODS: All patients with calcaneal fractures who received osteosynthesis with either plate or C-Nail between January 2016 and October 2019 in our institution were retrospectively analyzed. A subgroup analysis was performed with matched pairs (matching Sanders type, age, Böhler's angle postoperative in normal range, 33 pairs). Endpoints were postoperative complication rate, bone healing, full weight-bearing and functional outcome. Treatment groups were compared using Fisher's exact test for binary data, and Mann-Whitney U-test for continuous data. A p-value < 0.05 was considered statistically significant. RESULTS: One hundred and one calcaneal fractures were included (C-Nail n = 52, plate n = 49). Patients with C-Nail developed significantly less postoperative complications (p = 0.008), especially wound edge necrosis (p < 0.001). Screw malposition was found more often in the C-Nail group. The rates of achieving full weight-bearing as well as bone healing were comparable in both groups, but in each case significant faster in the C-nail subgroup. The results of the matched-pairs analysis were comparable. CONCLUSIONS: The postoperative complication rate was significantly lower in the C-Nail group. The C-Nail appears to be a successful alternative in the treatment of calcaneal fractures, even in Sanders IV fractures because of the minimal-invasive implantation as well as the high primary stability. Long-term analysis of this new implant including elaboration on functional outcome is planned. TRIAL REGISTRATION: Deutsches Register Klinischer Studien (DRKS) DRKS00020395 . Date of registration 3 January 2020.

Oral Rehabilitation With Dental Implants and the Importance of a Preventive Evaluation for Osteonecrosis of the Jaws Associated With Medications.

Osteonecrosis of the jaw is a possible oral complication resulting from antiresorptive therapies, such as bisphosphonates (Bfs). Although the etiology is not entirely clear, it has been shown to be dependent on several factors, with the traumatic stimulation caused by the placement of teeth implants indicated as one of the predisposing factors to this pathology. The indications and preventive methods for performing these procedures have been questioned, making it essential to determine the proper protocols. Thus, the present study aims to discuss the risks of the development of osteonecrosis in patients undergoing dental implant surgery who use Bfs as well as to discuss related local and systemic factors and possible methods for preventing this side effect. The study also aims to present a clinical case of an osteopenic patient who used Bfs and underwent rehabilitation through implants according to specific protocols, which resulted in successful treatment.

Taurine Inhibits Glucocorticoid-Induced Bone Mitochondrial Injury, Preventing Osteonecrosis in Rabbits and Cultured Osteocytes.

Mitochondrial injury has recently been implicated in the pathogenesis of glucocorticoid-induced osteonecrosis. Using cultured osteocytes and a rabbit model, we investigated the possibility that taurine (TAU), which is known to play a role in the preservation of mitochondrial function, might also prevent the development of osteonecrosis. To reduplicate the intraosseous environment seen in glucocorticoid-induced osteonecrosis, dexamethasone (Dex) was added to MLO-Y4 cultured in 1% hypoxia (H-D stress environment). An in vitro study was conducted in which changes in mitochondrial transcription factor A (TFAM), a marker of mitochondrial function, and ATP5A produced by mitochondria, induced by the presence/absence of taurine addition were measured. To confirm the effect of taurine in vivo, 15 Japanese White rabbits were administered methylprednisolone (MP) 20 mg/kg as a single injection into the gluteus muscle (MP+/TAU- group), while for 5 consecutive days from the day of MP administration, taurine 100 mg/kg was administered to 15 animals (MP+/TAU+ group). As a control 15 untreated rabbits were also studied. The rabbits in each of the groups were sacrificed on the 14th day after glucocorticoid administration, and the bilateral femora were harvested. Histopathologically, the incidence of osteonecrosis was quantified immunohistochemically by quantifying TFAM and ATP5A expression. In the rabbits exposed to an H-D stress environment and in MP+/TAU- group, TFAM and ATP5A expression markedly decreased. With addition of taurine in the in vitro and in vivo studies, the expression of TFAM and ATP5A was somewhat decreased as compared with Dex-/hypoxia- or MP-/TAU- group, while improvement was noted as compared with Dex+/hypoxia+ or MP+/TAU- group. In rabbits, the incidence of osteonecrosis was 80% in MP+/TAU- group, in contrast to 20% in the taurine administered group (MP+/TAU+), representing a significant decrease. Since taurine was documented to exert a protective effect on mitochondrial function by inhibiting the mitochondrial dysfunction associated with glucocorticoid administration, we speculated that it might also indirectly help to prevent the development of osteonecrosis in this context. Since taurine is already being used clinically, we considered that its clinical application would also likely be smooth.