Safety of bisphosphonates

Development of a zoledronate-modified functional alginate hydrogel with effects of promoting osteogenesis for potential osteoporosis treatment

Osteoporosis is one of the most prevalent age-related diseases worldwide. It is characterized by a systemic deterioration in bone strength (bone density and bone mass), leading to an increase in fragility fractures. The complex pathological environment of osteoporosis presents a significant challenge to the induction of bone regeneration under osteoporotic conditions. Therefore, the development of a system for local delivery of active substances with osteoinductive effects is of practical significance in the clinical treatment of osteoporosis. In this study, we successfully loaded the anti-osteoporotic small molecule drug zoledronate (ZOL) into calcium alginate to prepare a biologically functional hydrogel, designated as ALG-ZOL-Ca. The prepared ALG-ZOL-Ca hydrogel gels quickly, making the hydrogel easy to inject and adapt to irregularly shaped bone defects, and simultaneously exhibits good bioactivity and osteoconductivity. The RT-qPCR results suggested that this hydrogel effectively promoted the expression levels of β-catenin and Axin2, which indicating a stimulative effect on the Wnt/β-catenin pathway in vitro. Moreover, ALG-ZOL-Ca hydrogel effectively promoted the expression of the OCN and SP7 genes. Therefore, this study proposes a new functional composite hydrogel that provides a potential treatment strategy for osteoporosis.

Additional effects of herbal medicine combined with bisphosphonates for primary osteoporosis: a systematic review and meta-analysis

Background

Osteoporosis (OP) is a significant medical issue associated with population aging. Recent research on herbal medicines (HMs) for OP has been increasing, with these therapies sometimes used in conjunction with bisphosphonates (BPs), the standard treatment for OP. We conducted a systematic review and meta-analysis to evaluate the effects of combining HMs with BPs on improving bone mineral density (BMD) in patients with primary OP.

Methods

We searched nine databases-PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure Wanfang, KISS, Kmbase, Science On, and Oasis-up to 31 August 2023. We selected randomized controlled trials (RCTs) comparing BMD between HMs plus BPs and BPs alone in primary OP. A meta-analysis with BMD as the primary outcome was performed using RevMan version 5.4. Study quality and evidence certainty were assessed through Cochrane's risk of bias2 and GRADE.

Results

Out of 43 RCTs involving 4,470 participants (mean age 65.8 ± 6.6 years), 35 RCTs with 3,693 participants were included in the meta-analysis. The combination of HMs and BPs was found to be more effective in improving BMD compared to BPs alone, with improvements of 0.10 g/cm2 at the lumbar spine (33 RCTs, 95% CI: 0.07-0.12, p < 0.001, I2 = 93%) and 0.08 g/cm2 at the femoral neck (20 RCTs, 95% CI: 0.05-0.12, p < 0.001, I2 = 94%), though this result was associated with high heterogeneity, high risk of bias, and very low certainty of evidence.

Conclusion

Our data suggest the possibility that combining HMs with BPs may improve BMD in primary OP more effectively than using BPs alone. However, the results should be interpreted with caution due to the high heterogeneity and low quality of the studies included in the review. Therefore, further well-designed RCTs are needed to confirm these findings.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023392139.

Crebanine mitigates glucocorticoid-induced osteonecrosis of the femoral head by restoring bone remodelling homeostasis via attenuating oxidative stress

The onset of osteonecrosis of the femoral head (ONFH) is intimately associated with the extensive administration of glucocorticoids (GCs). Long-term stimulation of GCs can induce oxidative stress in both osteoclasts (OCs) and osteoblasts (OBs), resulting in the disturbance of bone remodelling. An alkaloid named crebanine (CN) demonstrates pharmacological properties including anti-inflammation and reactive oxygen species (ROS) modulation. Our objective is to assess the therapeutic potential of CN in treating ONFH and elucidate the associated underlying mechanisms. The network pharmacology analysis uncovered that CN played a role in regulating ROS metabolism. In vitro, CN demonstrated its ability to reduce the dexamethasone (DEX)-stimulated generation of OCs and suppress their resorptive function by downregulating the level of osteoclast marker genes. Concurrently, CN also mitigated DEX-induced damage to OBs, facilitating the restoration of osteoblast marker gene expression, cellular differentiation and function. These effects were achieved by CN augmenting the antioxidant system to reduce intracellular ROS levels. Furthermore, in vitro results were corroborated by micro-CT and histological data, which also showed that CN attenuated MPS-induced ONFH in mice. This study highlights the therapeutic potential of CN in counteracting GCs-induced ONFH.

Clinical challenges and considerations in pharmacotherapy of osteoporosis due to menopause

INTRODUCTION

Osteoporosis is a chronic systemic skeletal disorder characterized by compromised bone strength and an increased risk of fracture, with a high prevalence worldwide. It is associated with a negative quality of life and an increased morbidity and mortality. Postmenopausal women are more prone to develop osteoporosis, and many of them will suffer at least one fragility fracture along their lifetime.

AREAS COVERED

This review starts by summarizing the pathogenesis of postmenopausal osteoporosis (PMO), with focus on the estrogen deficiency-associated bone loss. It continues with the current PMO diagnostic and fracture risk prediction tools, and it finally addresses management of PMO. All the efficacy and safety profiles of the current and future osteoporosis medications are reviewed. Furthermore, strategies to optimize the long-term disease management are discussed. For this review, only publications in English language were selected. References were extracted from PubMed, Embase, and Medline.

EXPERT OPINION

PMO disease management is far from being ideal. Educational and communication programs with the goal of improving disease knowledge and awareness, as well as reducing the health-care gap, should be implemented. In addition, most effective sequential prevention and treatment strategies should be initiated from the early menopause.

An acute phase reaction from zoledronate mimicking symptoms seen in opioid withdrawal: a case report

BACKGROUND

Zoledronate, a bisphosphonate, is a potent first-line treatment for osteoporosis. It is also a preferred treatment for hypercalcemia especially when unresponsive to intravenous fluids. Bisphosphonates can cause acute phase reactions that mimic opioid withdrawal symptoms, which can confound provider decision-making. Our case highlights cognitive bias involving a patient with opioid use disorder who received zoledronate for hypercalcemia secondary to immobilization and significant bone infection.

CASE PRESENTATION

A 41-year-old male is admitted with a past medical history of active intravenous opioid use complicated by group A streptococcal bacteremia with L5-S1 discitis and osteomyelitis, L2-L3 osteomyelitis, and left ankle abscess/septic arthritis status post left ankle washout. His pain was well-controlled by acute pain service with ketamine infusion (discontinued earlier), opioids, acetaminophen, buprenorphine-naloxone, cyclobenzaprine, gabapentin, and naproxen. Intravenous opioids were discontinued, slightly decreasing the opioid regimen. A day later, the patient reported tachycardia, diaphoresis, myalgias, and chills, which the primary team reconsulted acute pain service for opioid withdrawal. However, the patient received a zoledronate infusion for hypercalcemia, on the same day intravenous opioids were discontinued. He had no other medications known to cause withdrawal-like symptoms per chart review. Therefore, it was suspected that an acute phase reaction occurred, commonly seen within a few days of bisphosphonate use.

CONCLUSION

Zoledronate, well known for causing acute phase reactions, was likely the cause of withdrawal-like symptoms. Acute phase reactions with bisphosphonates mostly occur in the first infusion, and the incidence decreases with subsequent infusions. Symptoms typically occur 24-72 h post-infusion, and last at most for 72 h. Cognitive bias led the primary team to be concerned with opioid withdrawal rather than investigating other causes for the patient's presentation. Therefore, providers should thoroughly investigate potential etiologies and rule them out accordingly to provide the best care. Health care providers should also be aware of the implicit biases that potentially impact the quality of care they provide to patients.

Editorial Commentary: Postoperative Zoledronic Acid Improves Tendon Healing but Does Not Affect Outcomes in Rotator Cuff Repair Patients With Postmenopausal Osteoporosis

Understanding the preoperative risk factors for successful rotator cuff repair (RCR) and ways to optimize these factors is an evolving area of study. The Rotator Cuff Healing Index and other proxy risk factors for failed rotator cuff healing have implicated significant fatty infiltration, muscular atrophy, advanced chronological age, tear size and retraction, and ultimately, osteoporosis. Although structural (or biological) augmentation and tendon transfer have been proposed as solutions for the alarmingly high rate of failure after primary RCR, other options may preferentially focus on the enthesis and underlying osseous footprint. Currently, bisphosphonates are frequently used in the treatment of osteoporosis and prevention of fragility fractures. However, burgeoning evidence suggests that postoperative zoledronic acid may have clinical utility after rotator cuff and other tendon repairs. In the cost-conscious world of evidence-based medicine, the added economic burden of additional medications and office visits may or may not improve patient outcomes-much less confer added value. Our advice to fellow shoulder surgeons: Wait for further information, but continue to holistically consider and optimize risk factors for poor soft-tissue healing. Although the addition of postoperative bisphosphonates may improve suture anchor fixation and promote a better foundation for healing, it will not immediately transform your RCR success rates.

Transcriptional reprogramming during human osteoclast differentiation identifies regulators of osteoclast activity

Enhanced osteoclastogenesis and osteoclast activity contribute to the development of osteoporosis, which is characterized by increased bone resorption and inadequate bone formation. As novel antiosteoporotic therapeutics are needed, understanding the genetic regulation of human osteoclastogenesis could help identify potential treatment targets. This study aimed to provide an overview of transcriptional reprogramming during human osteoclast differentiation. Osteoclasts were differentiated from CD14+ monocytes from eight female donors. RNA sequencing during differentiation revealed 8 980 differentially expressed genes grouped into eight temporal patterns conserved across donors. These patterns revealed distinct molecular functions associated with postmenopausal osteoporosis susceptibility genes based on RNA from iliac crest biopsies and bone mineral density SNPs. Network analyses revealed mutual dependencies between temporal expression patterns and provided insight into subtype-specific transcriptional networks. The donor-specific expression patterns revealed genes at the monocyte stage, such as filamin B (FLNB) and oxidized low-density lipoprotein receptor 1 (OLR1, encoding LOX-1), that are predictive of the resorptive activity of mature osteoclasts. The expression of differentially expressed G-protein coupled receptors was strong during osteoclast differentiation, and these receptors are associated with bone mineral density SNPs, suggesting that they play a pivotal role in osteoclast differentiation and activity. The regulatory effects of three differentially expressed G-protein coupled receptors were exemplified by in vitro pharmacological modulation of complement 5 A receptor 1 (C5AR1), somatostatin receptor 2 (SSTR2), and free fatty acid receptor 4 (FFAR4/GPR120). Activating C5AR1 enhanced osteoclast formation, while activating SSTR2 decreased the resorptive activity of mature osteoclasts, and activating FFAR4 decreased both the number and resorptive activity of mature osteoclasts. In conclusion, we report the occurrence of transcriptional reprogramming during human osteoclast differentiation and identified SSTR2 and FFAR4 as antiresorptive G-protein coupled receptors and FLNB and LOX-1 as potential molecular markers of osteoclast activity. These data can help future investigations identify molecular regulators of osteoclast differentiation and activity and provide the basis for novel antiosteoporotic targets.

Bisphosphonates and osteonecrosis of the jaws: Clinical and forensic aspects

OBJECTIVE

This manuscript aims to provide a comprehensive review of the current knowledge in the pathophysiology, diagnosis, prevention, and other relevant clinical and forensic aspects of a potentially severe complication known as medication-related osteonecrosis of the jaw (MRONJ) while synthesizing state-of-the-art information on bisphosphonates and introducing a possible differential diagnosis.

DESIGN

An extensive search was conducted in PubMed (U.S. National Library of Medicine) without a time or language constraint, focusing on the epidemiology, pathophysiology, risk factors, site specificity, signs and symptoms, differential diagnosis, prevention, and forensic aspects of MRONJ. All types of original articles, reviews, case reports, short communications, opinion articles, guidelines, and letters to editors were considered to produce a complete review on this subject.

RESULTS

MRONJ prevention relies on a multidisciplinary approach and is critical since truly effective treatments are lacking. This therapeutic challenge is partly due to uncertainty regarding this condition's pathophysiology. Differential diagnosis of osteonecrosis of the jaws associated with krokodil abuse, one of the most dangerous and homemade psychoactive illicit substances, should be considered.

CONCLUSIONS

Further research into the etiology and site specificity of MRONJ is encouraged, aiming to develop novel treatment prospects. Indeed, comprehending this would allow for increased efficacy and therapeutic options while emphasizing the importance of prevention. In addition, we advocate for greater consensus among the various societies regarding MRONJ's treatment and management.

Bisphosphonates and Atypical Femur Fractures: Is the Relationship Causal or Casual?

Bisphosphonates (BPs) are a time-tested drug class with multivariate use cases. They are used in pathologies ranging from osteoporosis to Paget's disease, and also help in accelerated fracture healing. They have been used to treat both benign and malignant lesions of the skeletal system since a long time. However, there have been reports of increased incidences of atypical femoral fractures (AFFs) in patients exhibiting chronic use of bisphosphonates in the past years. This has led to the widespread dissuasion of physicians and practitioners from using the drug class. By means of this review of the literature, the authors aim to investigate the relationship between BP use and its association with AFFs. The review focuses on and elucidates the basic pharmacology of BPs and goes on to illustrate the indications of BPs in various pathologies of the musculoskeletal system, further exploring the effects of BPs on the healing of various bony fractures. The authors also explore the incidences of other pathologies, such as osteonecrosis of the jaw and nephropathies associated with BP use, and elaborate on their features. Through this review, the authors have tried to educate and induce critical thinking on the part of clinicians and medical professionals in regard to prescribing BPs to patients that need them, by keeping in mind the risk-reward relationship that accompanies their use.

A colloidal hydrogel-based drug delivery system overcomes the limitation of combining bisphosphonates with bioactive glasses: in vitro evidence of a potential selective bone cancer treatment allied with bone regeneration

Bisphosphonates are a class of drugs that induce bone cancer cell death and favor bone regeneration, making them suitable for bone cancer treatment. However, when combined with bioactive glasses to enhance bone regeneration, a chemical bond between biphosphonates and the glass surface inactivates their mechanism of action. A new colloidal hydrogel-based drug delivery system could overcome that limitation once bisphosphonates, such as zoledronic acid (ZA), are incorporated into hydrogel micelles, avoiding their interaction with the glass surface. In this work, we proposed formulations based on a poloxamer 407 thermo-responsive hydrogel matrix containing holmium-doped bioactive glass nanoparticles and different concentrations (0.05 and 5 mg/mL) of ZA. We characterized the influence of the glass and the ZA on the hydrogel properties. In addition, a drug concentration screening was performed, and biological characterizations evaluated the best result. The biological characterization consisted of evaluating cytotoxicity and in vitro bone regeneration ability through cell migration and quantification of genes related to osteogeneses through RT-PCR. The results suggest that the addition of glasses and ZA to the poloxamer did not significantly influence the sol-gel transition of the hydrogels (around 13 °C) regardless of the ZA content. However, the ZA at high concentration (PL-ZA100) decreased the enthalpy of gel formation from 68 to 43 kJ.mol^-1 when compared with the pure hydrogel formulation (PL), suggesting a water structurer role of ZA, which is withdrawn when glass particles are added to the system (PL-BG5Ho-ZA100). Solid-state 31P nuclear resonance spectroscopy results showed that part of the ZA is chemically bonded to the glass surface, which explains the withdrawal in the water structurer role of ZA when the glasses were incorporated into the hydrogel. Besides, based on the drug release results, we proposed a model where part of the ZA is "free," encapsulated in the hydrogel matrix, while another part of the ZA is bonded to the glass surface. Finally, considering the in vitro results and our proposed model, the ratio between "free" and "bonded" ZA in our drug delivery systems showed in vitro evidence of a cancer treatment that selectively kills osteosarcoma cells while still favoring an osteogenic microenvironment. By overcoming the limitation of combining bisphosphonates with bioactive glasses, hydrogel-based drug delivery systems can be a solution for the development of new formulations proposed for bone cancer treatment in conjunction with bone regeneration.

Oral bisphosphonates: Adverse effects on the oral mucosa not related to the jaw bones. A scoping review

BACKGROUND

Oral bisphosphonates are widely used in the treatment of bone resorptive diseases. There is an evidence that oral bisphosphonates can exert adverse effects on the oral mucosa independently of their effects on the jaw bones.

OBJECTIVE

To systematically map the literature on adverse effects of oral bisphosphonates on the oral mucosa of adults with bone resorptive diseases.

DESIGN

Scoping review of the literature, including different study designs.

METHODS

Systematic searches of the PubMed, LILACS, Google Scholar and EMBASE databases were conducted. Two independent reviewers screened titles and abstracts according to predetermined criteria.

RESULTS

The search retrieved 26 unique articles, comprising 22 case reports, one case series and three reviews describing a total of 56 cases of oral adverse events related to oral bisphosphonates. 88% of the reported cases were female suffering from comorbidities other than metabolic bone diseases. The improper use of the oral bisphosphonate was the most suspected cause of the adverse effect on the oral mucosa. Its management mainly involved withdrawal of the medication.

CONCLUSION

Adverse effects on the oral mucosa can develop from using oral bisphosphonates. Standardised registration of these adverse effects in university clinics and private practises could provide additional information about their occurrence and severity.

FAEE exerts a protective effect against osteoporosis by regulating the MAPK signalling pathway

CONTEXT

Ferulic acid ethyl ester (FAEE) is abundant in Ligusticum chuanxiong Hort. (Apiaceae) and grains, and possesses diverse biological activities; but the effects of FAEE on osteoporosis has not been reported.

OBJECTIVE

This study investigated whether FAEE can attenuate osteoclastogenesis and relieve ovariectomy-induced osteoporosis via attenuating mitogen-activated protein kinase (MAPK).

MATERIALS AND METHODS

We stimulated RAW 264.7 cells with receptor activator of NF-κB ligand (RANKL) followed by FAEE. The roles of FAEE in osteoclast production and osteogenic resorption of mature osteoclasts were evaluated by tartrate resistant acid phosphatase (TRAP) staining, expression of osteoclast-specific genes, proteins and MAPK. Ovariectomized (OVX) female Sprague-Dawley rats were administered FAEE (20 mg/kg/day) for 12 weeks to explore its potential in vivo, and then histology was undertaken in combination with cytokines analyses.

RESULTS

FAEE suppressed RANKL-induced osteoclast formation (96 ± 0.88 vs. 15 ± 1.68) by suppressing the expression of osteoclast-specific genes, proteins and MAPK signalling pathway related proteins (p-ERK/ERK, p-JNK/JNK and p-P38/P38) in vitro. In addition, OVX rats exposed to FAEE maintained their normal calcium (Ca) (2.72 ± 0.02 vs. 2.63 ± 0.03, p < 0.05) balance, increased oestradiol levels (498.3 ± 9.43 vs. 398.7 ± 22.06, p < 0.05), simultaneously reduced levels of bone mineral density (BMD) (0.159 ± 0.0016 vs. 0.153 ± 0.0025, p < 0.05) and bone mineral content (BMC) (0.8 ± 0.0158 vs. 0.68 ± 0.0291, p < 0.01).

DISCUSSION AND CONCLUSIONS

These findings suggested that FAEE could be used to ameliorate osteoporosis by the MAPK signalling pathway, suggesting that FAEE could be a potential therapeutic candidate for osteoporosis.

Drug distribution evaluation using FT-IR imaging on the surface of a titanium alloy coated with zinc titanate with potential application in the release of drugs for osteoporosis

The drugs most commonly used in the treatment of osteoporosis are bisphosphonates. This disease results in low mineral density and a weakened bone microstructure. The delivery methods for these drugs have many disadvantages, and new ones are being searched for. In this work, biocompatible zinc titanate coated titanium implants were obtained as potential new carriers for drugs. Such a material will release the drug, and it will have antibacterial properties. Gradual release of the bisphosphonate will have a positive effect on the recovery process and osteointegration. In addition, the drug will be released around the affected bones. The effectiveness of the modification and attachment of the drug was confirmed by SEM, XPS, EDS, FT-IR imaging, and UV-VIS. It was shown that the risedronate could be almost completely released upon contact with body fluids within a week. The drug is evenly distributed over the entire surface of the alloy as confirmed by FT-IR imaging. The results presented in this work will allow for the preparation of endoprostheses that release the drug and have antibacterial properties.

Bisphosphonates Related Ocular Side Effects: A Case Series and Review of Literature

OBJECTIVE

To describe the clinical features of patients with bisphosphonate related ocular side effects (BROSE).

METHODS

The medical records of all patients with BROSE between January 2009 and December 2019 were reviewed.

RESULTS

Nine cases with BROSE were identified. All subjects were female. Median age at diagnosis was of 69 years. The leading indication for bisphosphonate treatment was osteoporosis (n=7), Paget's disease of bone (n=1) and breast cancer (n=1). Six (66.67%) patients presented with uveitis, one (11%) episcleritis and two (22%) with orbital inflammation. Five events (55.5%) occurred within 10 days of initiating the bisphosphonate and the rest (44.44%) developed within 2 weeks to 3 years later. Four (44.44%) patients had concurrent thyroid disease. An association was found between underlying thyroid disease or autoimmunity.

CONCLUSION

BROSE is an uncommon complication of bisphosphonate therapy occurring more frequently in patients with an autoimmune predisposition.

Acute Effects of Kisspeptin Administration on Bone Metabolism in Healthy Men

CONTEXT

Osteoporosis results from disturbances in bone formation and resorption. Recent nonhuman data suggest that the reproductive hormone kisspeptin directly stimulates osteoblast differentiation in vitro and thus could have clinical therapeutic potential. However, the effects of kisspeptin on human bone metabolism are currently unknown.

OBJECTIVE

To assess the effects of kisspeptin on human bone metabolism in vitro and in vivo.

METHODS

In vitro study: of Mono- and cocultures of human osteoblasts and osteoclasts treated with kisspeptin. Clinical study: Randomized, placebo-controlled, double-blind, 2-way crossover clinical study in 26 men investigating the effects of acute kisspeptin administration (90 minutes) on human bone metabolism, with blood sampling every 30 minutes to +90 minutes. Cells for the in vitro study were from 12 male blood donors and 8 patients undergoing hip replacement surgery. Twenty-six healthy eugonadal men (age 26.8 ± 5.8 years) were included in the clinical study. The intervention was Kisspeptin (vs placebo) administration. The main outcome measures were changes in bone parameters and turnover markers.

RESULTS

Incubation with kisspeptin in vitro increased alkaline phosphatase levels in human bone marrow mesenchymal stem cells by 41.1% (P = .0022), and robustly inhibited osteoclastic resorptive activity by up to 53.4% (P < .0001), in a dose-dependent manner. Kisspeptin administration to healthy men increased osteoblast activity, as evidenced by a 20.3% maximal increase in total osteocalcin (P = .021) and 24.3% maximal increase in carboxylated osteocalcin levels (P = .014).

CONCLUSION

Collectively, these data provide the first human evidence that kisspeptin promotes osteogenic differentiation of osteoblast progenitors and inhibits bone resorption in vitro. Furthermore, kisspeptin acutely increases the bone formation marker osteocalcin but not resorption markers in healthy men, independent of downstream sex steroid levels. Kisspeptin could therefore have clinical therapeutic application in the treatment of osteoporosis.

The Abcc6a Knockout Zebrafish Model as a Novel Tool for Drug Screening for Pseudoxanthoma Elasticum

Pseudoxanthoma elasticum (PXE) is a multisystem ectopic mineralization disorder caused by pathogenic variants in the ABCC6 gene. Though complications of the disease can be treated, PXE itself remains currently intractable. A strategy for rapid and cost-effective discovery of therapeutic drugs would be to perform chemical compound screening using zebrafish, but this approach remains to be validated for PXE. In this paper, we validate a stable CRISPR/Cas9 abcc6a knockout zebrafish model–which has spinal column hypermineralization as its primary phenotypic feature–as a model system for compound screening in ectopic mineralization. We evaluated the anti-mineralization potential of five compounds, which had (anecdotal) positive effects reported in Abcc6 knockout mice and/or PXE patients. Abcc6a knockout zebrafish larvae were treated from 3 to 10 days post-fertilization with vitamin K1, sodium thiosulfate, etidronate, alendronate or magnesium citrate and compared to matching controls. Following alizarin red S staining, alterations in notochord sheath mineralization were semiquantified and found to largely congrue with the originally reported outcomes. Our results demonstrate that the use of this abcc6a knockout zebrafish model is a validated and promising strategy for drug discovery against ectopic mineralization.

In vitro evidence for the involvement of H2S pathway in the effect of clodronate during inflammatory response

Clodronate is a bisphosphonate agent commonly used as anti-osteoporotic drug. Throughout its use, additional anti-inflammatory and analgesic properties have been reported, although the benefits described in the literature could not solely relate to their inhibition of bone resorption. Thus, the purpose of our in vitro study is to investigate whether there are underlying mechanisms explaining the anti-inflammatory effect of clodronate and possibly involving hydrogen sulphide (H₂S). Immortalised fibroblast-like synoviocyte cells (K4IM) were cultured and treated with clodronate in presence of TNF-α. Clodronate significantly modulated iNOS expression elicited by TNF-α. Inflammatory markers induced by TNF-α, including IL-1, IL-6, MCP-1 and RANTES, were also suppressed following administration of clodronate. Furthermore, the reduction in enzymatic biosynthesis of CSE-derived H₂S, together with the reduction in CSE expression associated with TNF-α treatment, was reverted by clodronate, thus rescuing endogenous H₂S pathway activity. Clodronate displays antinflammatory properties through the modulation of H₂S pathway and cytokines levels, thus assuring the control of the inflammatory state. Although further investigation is needed to stress out how clodronate exerts its control on H₂S pathway, here we showed for the first the involvement of H₂S in the additive beneficial effects observed following clodronate therapy.

Osteonecrosis of the Femoral Head: an Updated Review of ARCO on Pathogenesis, Staging and Treatment

Non-traumatic osteonecrosis of the femoral head (ONFH) usually affects adults younger than 50 years and frequently leads to femoral head collapse and subsequent arthritis of the hip. It is becoming more prevalent along with increasing use of corticosteroids for the adjuvant therapy of leukemia and other myelogenous diseases as well as management of organ transplantation. This review updated knowledge on the pathogenesis, classification criteria, staging system, and treatment of ONFH.

The effect of pamidronate delivery in bisphosphonate-naïve patients on neutrophil chemotaxis and oxidative burst

The pathogenesis of medication-related osteonecrosis of the jaw (MRONJ), a morbid condition associated with bisphosphonate administration, has not been fully elucidated. Recent research utilizing a murine model has revealed that the neutrophil becomes dysfunctional following exposure to bisphosphonates. Accordingly, the impairment of neutrophil function could play an important role in the pathogenesis of MRONJ via an infectious mechanism mediated by the suppression of the innate immune system. Currently, the existing human data are insufficient to substantiate this theory. To investigate, we isolated neutrophils from blood and oral rinse samples from bisphosphonate-naïve patients who were recently diagnosed with multiple myeloma both prior to and one month following their initial infusion of pamidronate, an intravenous bisphosphonate agent. Stimulated blood and oral neutrophil superoxide production and chemotactic capabilities were found to be impaired relative to baseline values. These results suggest that impaired neutrophil function may partially contribute to the aetiology underlying the pathophysiological processes linked to the development of MRONJ. Further, as the functional status of circulating neutrophils was reflected in the oral cavity where sampling can be accomplished in a non-invasive fashion, it is conceivable that neutrophil function could serve as a potential biomarker for MRONJ prognostication.

Update on Equine Odontoclastic Tooth Resorption and Hypercementosis

Equine odontoclastic tooth resorption and hypercementosis (EOTRH) is a progressive, painful disease, affecting incisors, canines, and cheek teeth. Examination findings include gingival inflammation, gingival recession and/or hyperplasia, subgingival swelling, bulbous enlargement of teeth, associated periodontal disease, pathologic tooth fracture, and/or tooth mobility and loss. Current hypotheses include biomechanical stresses and secondary bacterial involvement. Early recognition allows case management, but it is a progressive disease. Owner education is crucial; horses with complete or multiple extractions have a favorable prognosis. Human oral and dental health may be affected by bisphosophonate use; long-term effects of these drugs are currently unknown in horses.

Incomplete atypical femoral fractures after bisphosphonate use in postmenopausal women

PURPOSE

This study aimed to determine the prevalence of incomplete atypical femoral fractures (iAFFs) in postmenopausal women using bisphosphonates and to investigate the potential risk factors for the development of iAFF.

METHODS

The national health-care records system indicated that 2746 postmenopausal women in our region aged ≥50 years were taking bisphosphonates. Using an assumed iAFF prevalence of 10% and levels of 5% α significance and ±5% precision, we calculated that a sample size of 132 participants was needed for this study. The patients were randomly selected and invited to the hospital. Radiographs and bone scans were used to evaluate each patient for iAFF. Bone mineral density, 25-hydroxy vitamin D, parathyroid hormone, and alkaline phosphatase measurements were performed.

RESULTS

The mean age of the study population was 72.79 ± 7.35 years, and the mean duration of bisphosphonate use was 7.7 ± 3.4 years. We found iAFF in 14 (10.6%) patients, and 3 patients had bilateral involvement. Of the 17 femurs with iAFF, a proximal third location was seen in 2 patients (11.8%), a mid-third location in 14 (82.4%), and a distal third location in 1 (5.9%). The duration of bisphosphonate use was longer, and parathyroid hormone levels were higher in patients with iAFF compared to those without an incomplete fracture.

CONCLUSION

We found a relatively higher prevalence of iAFF in postmenopausal women using bisphosphonate. Early identification and treatment of iAFF is crucial for reducing potential patient morbidity and hospital costs.

Regeneration of Cochlear Synapses by Systemic Administration of a Bisphosphonate

Sensorineural hearing loss (SNHL) caused by noise exposure and attendant loss of glutamatergic synapses between cochlear spiral ganglion neurons (SGNs) and hair cells is the most common sensory deficit worldwide. We show here that systemic administration of a bisphosphonate to mice 24 h after synaptopathic noise exposure regenerated synapses between inner hair cells and SGNs and restored cochlear function. We further demonstrate that this effect is mediated by inhibition of the mevalonate pathway. These results are highly significant because they suggest that bisphosphonates could reverse cochlear synaptopathy for the treatment of SNHL.

Perforation of gastric volvulus within a giant hiatus hernia secondary to alendronate: A rare complication of bisphosphonate use

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A case of perforation due to alendronate in patient with gastric volvulus within giant hiatus hernia.

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Bisphosphonates can have devastating gastrointestinal side effects.

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Gastric or oesophageal perforation due to bisphosphonates is rare but serious.

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Bisphosphonates should be avoided in those with functional or anatomical disorders of the gastrointestinal tract.

Introduction

Bisphosphonates are commonly used in the treatment of metabolic bone disease. However, they are associated with gastrointestinal side effects including acid reflux, mucosal erosion, and oesophageal stricture. We present a rare case of alendronate causing perforated gastric volvulus in a patient with giant hiatus hernia.

Presentation of case

An 82-year-old woman presented to our hospital with central chest pain, palpitations and new onset atrial fibrillation on the background of 2 weeks of vomiting. Computed tomography (CT) imaging revealed a perforated, mixed type organoaxial/mesoenteroaxial gastric volvulus within a giant hiatus hernia, with partial gastric outlet obstruction. The patient underwent laparoscopic reduction of hiatus hernia and gastric volvulus, conversion to laparotomy, and distal gastrectomy with Bilroth II reconstruction. An alendronate tablet was found in the right mediastinum. The patient had a prolonged post-operative course and was discharged home after completing extensive physical rehabilitation.

Discussion

Bisphosphonates are widely used to treat metabolic bone disease, however can have devastating adverse effects on the gastrointestinal tract. There are a number of mechanisms postulated for how these medications cause injury to the gastric and oesophageal mucosa.

Conclusion

This case illustrates the importance of considering the gastrointestinal effects associated with bisphosphonates when prescribing them to patients, especially those with functional or anatomical disorders of the gastrointestinal tract. The presence of a large hiatus hernia should be a contraindication to prescribing alendronate.

HNGF6A Inhibits Oxidative Stress-Induced MC3T3-E1 Cell Apoptosis and Osteoblast Phenotype Inhibition by Targeting Circ_0001843/miR-214 Pathway

Humanin (HN), a mitochondrial derived peptide, plays cyto-protective role under various stress. In this study, we aimed to investigate the effects of HNGF6A, an analogue of HN, on osteoblast apoptosis and differentiation and the underlying mechanisms. Cell proliferation of murine osteoblastic cell line MC3TC-E1 was examined by CCK8 assay and Edu staining. Cell apoptosis was detected by Annexin V assay under H₂O₂ treatment. The differentiation of osteoblast was determined by Alizarin red S staining. We also tested the expression of osteoblast phenotype related protein by real-time PCR and Western blot. The interaction between Circ_0001843 and miR-214, miR-214 and TAFA5 was examined by luciferase report assay. Circ_0001843 was inhibited by siRNA and miR-214 was suppressed by miR-214 inhibitor to determine the effects of Circ_0001843 and miR-214 on cell proliferation, apoptosis, and differentiation. HNGF6A, an analogue of HN, exerted cyto-protection and osteogenesis-promotion in MC3T3-E1 cells. The expression of osteoblast phenotype related protein was significantly induced by HNGF6A. Additionally, HNGF6A treatment decreased Circ_0001843 and increased miR-214 levels, as well as inhibited the phosphorylation of p38 and JNK. We further found that Circ_0001843 directly bound with miR-214, which in turn inhibited the phosphorylation of p38 and JNK. Furthermore, both Circ_0001843 overexpression and miR-214 knockdown significantly decreased the cyto-protection and osteogenic promotion of HNGF6A. In summary, our data showed that HNGF6A protected osteoblasts from oxidative stress-induced apoptosis and osteoblast phenotype inhibition by targeting Circ_0001843/miR-214 pathway and the downstream kinases, p38 and JNK.

Rutin Improves Bone Histomorphometric Values by Reduction of Osteoclastic Activity in Osteoporosis Mouse Model Induced by Bilateral Ovariectomy

Objective

Osteoporosis is a disease of unbalanced bone metabolism that results in low bone mineral density with increased bone fragility and propensity for fractures. The increased rate of bone fracture due to osteoporosis places a significant burden on public health care expenditures. Therefore, numerous studies have been designed and performed to identify the drugs or health foods that can improve the bone quality or quantity. This study was designed to evaluate and analyze the therapeutic effects of rutin on histomorphometric values of the spine and femur in an osteoporotic mouse model induced by bilateral ovariectomy.

Methods

Thirty female ICR mice (8 weeks old) underwent either a sham operation (only abdominal incision, sham group, n=10) or bilateral ovariectomy (n=20). The ovariectomized (OVX) animals were randomly divided into two groups : untreated OVX group (OVX-C, n=10), or rutin-administered group (OVX-R, n=10). The OVX-C group received weight-adjusted doses of saline vehicle and the OVX-R group received 50 mg/kg of rutin intraperitoneally, starting 1 day after surgery. At 4 and 8 weeks after surgery, serum estrogen, osteocalcin, alkaline phosphatase (ALP), and the telopeptide fragment of type I collagen C-terminus (CTX-1) were analyzed. Interleukin (IL)-1β, IL-6, IL-10, and tumor necrosis factor (TNF)-α were also analyzed. Bone histomorphometric parameters of the 4th lumbar vertebra and femur were determined by micro-computed tomography.

Results

In OVX-C group, ALP, osteocalcin, CTX-1, IL-1β, IL-6, and TNF-α levels were significantly increased at 4 and 8 weeks compared to sham operation group. Rutin administration after OVX statistically significantly reduced ALP, CTX-1, IL-1β, IL-6, and TNF-α levels at 4 and 8 weeks. Rutin administration also improves bone histomorphometric parameters including trabecular bone volume fraction, trabecular thickness, and trabecular number. Trabecular separation was also decreased in OVX-R group compared to OVX-C group.

Conclusion

The present study demonstrated that rutin has therapeutic effects on improving bone histomorphometric values in an OVX mouse model. The improvement in histomorphometric values may be associated with the reduction of osteoclastic activity via inhibition of IL-1β, IL-6, and TNF-α. In future studies, the mechanism for the effect of rutin on osteoporosis should be demonstrated more clearly to use rutin in human osteoporosis.

Oral Treatment With Bisphosphonates of Osteoporosis Does Not Increase the Risk of Severe Gastrointestinal Side Effects: A Meta-Analysis of Randomized Controlled Trials

INTRODUCTION

Bisphosphonates (BPs) are first-line therapy for osteoporosis. Adherence is usually low in chronic, asymptomatic diseases, but gastrointestinal (GI) side-effects can also contribute to low adherence in BP therapy and may necessitate a review by a gastroenterologist with or without gastroscopy.

AIMS

Our meta-analysis aims to determine the risk of severe GI adverse events due to oral BP therapy in osteoporotic patients.

METHODS

A systematic search was conducted in three databases up to September 2020 for randomized controlled trials (RCTs) detailing GI adverse events in adults with osteoporosis on BP compared to placebo. Risk ratios (RRs) with 95% confidence intervals (CI) were calculated for non-severe and severe adverse events indicating endoscopic procedure with the random-effects model. Statistical heterogeneity was assessed using chi² and I² statistics.

RESULTS

Forty-two RCTs with 39,047 patients with 9,999 non-severe and 1,503 severe GI adverse events were included. The incidence of non-severe and severe adverse events ranged between 0.3-54.9 and 0-10.3%, respectively. There was no difference between BP and control groups in terms of the risk of non-severe or severe side effects: RR=1.05 (CI: 0.98-1.12), I² = 48.1%, and RR=1.01 (CI: 0.92-1.12), I² = 0.0%, respectively. Subgroup analysis of the most commonly used BP, once-weekly alendronate 70 mg, revealed an association between bisphosphonates and the risk of non-severe GI adverse events, RR=1.16 (CI: 1.00-1.36), I² = 40.7%, while the risk of severe GI side effects was not increased in this subgroup, RR=1.20 (CI: 0.83-1.74), I² = 0.0%.

CONCLUSION

Our results show that bisphosphonates do not increase the risk of severe GI adverse events. However, the marked variability of the screening for side effects in the included studies, and the fact that in most of the studies GI diseases were exclusion criteria limits the strenght of evidence of our results. The conclusions drawn from the meta-analysis are therefore restricted to selected populations, and the results must be interpreted with caution.

Clinical evidence of the effect of bisphosphonates on pregnancy and the infant

Bisphosphonates (BPs) are potent inhibitors of osteoclast mediated bone resorption. These drugs are widely used in the management of osteoporosis and other diseases, characterized by high bone turnover. The effect of BPs on gestation and lactation, when they are used as therapeutic agents in premenopausal women, is yet unknown. We conducted a detailed literature review and identified the cases of BPs use in young women, as well as, the effects of this therapy on the gestation and the embryo. The published data, regarding the use of BPs in premenopausal women and their effects on the pregnancy outcome, are limited. However, we could identify the outcomes of 40 pregnant women, who had received BPs prior to or during pregnancy, that have been documented in the literature. All women had valid indications to receive BPs for serious bone metabolism conditions. We could not identify any prospective trials, which focus on pregnancy outcomes following after the in-utero exposure to BPs. In total, no serious adverse effects were reported. Problems related to the offspring, such as hypocalcemia and a tendency for low body weight (LBW), were self-resolving. In addition, no serious adverse outcomes were reported for women having completed pregnancy. Nevertheless, follow-up was limited for both outcomes suggesting the necessity of national and international registries.

Bisphosphonates-much more than only drugs for bone diseases

α,α-Bisphosphonates (BPs) are well established in the treatment of bone diseases such as osteoporosis and Paget's disease. Their successful application originates from their high affinity to hydroxyapatite. While the initially appreciated features of BPs are already beneficial to many patients, recent developments have further expanded their pleiotropic applications. This review describes the background of the interactions of BPs with bone cells that form the basis of the classical treatment. A better understanding of the mechanism behind their interactions allows for the parallel application of BPs against bone cancer and metastases followed by palliative pain relief. Targeted therapy with bone-seeking BPs coupled with a diagnostic agent in one particle resulted in theranostics which is also described here. For example, in such a system, BP moieties are bound to contrast agents used in magnetic resonance imaging or radionuclides used in positron emission tomography. In addition, another example of the pleiotropic function of BPs which involves targeting the imaging agents to bone tissues accompanied by pain reduction is presented in this work.

Reliability and diagnostic utility of radiographs in patients with incomplete atypical femoral fractures

OBJECTIVE

The aim of this study was to evaluate the sensitivity and specificity of radiographs in identifying incomplete atypical femoral fractures and to determine interobserver and intra-observer reliability.

MATERIALS AND METHODS

Anterior-posterior and lateral radiographs of 10 femurs with incomplete atypical femoral fractures confirmed using bone scintigraphy and magnetic resonance imaging, and 40 femurs without incomplete atypical femoral fractures confirmed using bone scintigraphy, were reviewed by 4 orthopedic surgeons and 4 radiology specialists. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were calculated to determine a diagnosis of incomplete atypical femoral fractures. Interobserver reliability was measured using Fleiss' kappa value, and intra-observer reliability was ascertained using Cohen's kappa statistic.

RESULTS

Mean sensitivity, specificity, accuracy, and the positive and negative predictive values were found to be 89, 89, 89, 67, and 97% respectively, in diagnosing incomplete atypical femoral fractures using radiographs. Interobserver reliability was found to be at a good level (Fleiss' kappa = 0.66, standard error = 0.03, 95% confidence interval = 0.61-0.71). Intra-observer Cohen's kappa values ranged from 0.53 to 0.91.

CONCLUSION

The use of radiography was satisfactory in identifying incomplete atypical femoral fractures, and the level of interobserver agreement was found to be good. As radiographs are associated with low positive predictive values, an advanced imaging method should be used when an increase in femoral cortical thickness is the only contributory factor to suspicion of an incomplete atypical femoral fracture.

Genetically-achieved disturbances to the expression levels of TNFSF11 receptors modulate the effects of zoledronic acid on growing mouse skeletons

Zoledronic acid (ZOL), a nitrogen bisphosphonate (N-BP), is currently used to treat and control pediatric osteolytic diseases. Variations in the intensity of the effects and side effects of N-BPs have been reported with no clear explanations regarding their origins. We wonder if such variations could be associated with different levels of RANKL signaling activity in growing bone during and after the treatment with N-BPs. To answer this question, ZOL was injected into neonate C57BL/6J mice with different genetically-determined RANKL signaling activity levels (Opg^+/+\Rank^Tg-, Opg^+/+\Rank^Tg+, Opg^+/-\Rank^Tg-, Opg^+/-\Rank^Tg+, Opg^-/-\Rank^Tg- and Opg^-/-\Rank^Tg+ mice) following a protocol (4 injections from post-natal day 1 to 7 at the dose of 50 μg/kg) that mimics those used in onco-pediatric patients. At the end of pediatric growth (1 and half months) and at an adult age (10 months), the bone morphometric and mineral parameters were measured using μCT in the tibia and skull for the different mice. A histologic analysis of the dental and periodontal tissues was also performed. At the end of pediatric growth, a delay in long bone and skull bone growth, a blockage of tooth eruption, some molar root alterations and a neoplasia-like structure associated with incisor development were found. Interestingly, the magnitude of these side effects was reduced by Opg deficiency (Opg^-/-) but increased by Rank overexpression (Rank^Tg). Analysis of the skeletal phenotype at ten months confirmed respectively the beneficial and harmful effects of Opg deficiency and Rank overexpression. These results validated the hypothesis that the RANKL signaling activity level in the bone microenvironment is implicated in the modulation of the response to ZOL. Further studies will be necessary to understand the underlying molecular mechanisms, which will help decipher the variability in the effects of N-BPs reported in the human population. SIGNIFICANT STATEMENTS: The present study establishes that in mice the RANKL signaling activity level is a major modulator of the effects and side-effects of bisphosphonates on the individual skeleton during growth. However, the modulatory actions are dependent on the ways in which this level of activity is increased. A decrease in OPG expression is beneficial to the skeletal phenotype observed at the end of growth, while RANK overexpression deteriorates it. Far removed from pediatric treatment, in adults, the skeletal phenotypes initially observed at the end of growth for the different levels of RANKL signaling activity were maintained, although significant improvement was associated only with reductions in OPG expression.

Is There a Role of Pharmacological Treatments in the Prevention or Treatment of Osteonecrosis of the Femoral Head?: A Systematic Review

Background

Various pharmacological treatments have been suggested to treat osteonecrosis of the femoral head. However, their practicability remains a controversial issue.

Methods

We systemically reviewed articles published during last 20 years to assess the efficacy and safety of the pharmacological treatments.

Results

To date, enoxaparin, statins, bisphosphonates, iloprost and acetylsalicylic acid have been practiced for the treatment of osteonecrosis. However, none of them were proven to be effective by high level studies, and most of them have adverse reactions.

Conclusions

No pharmacological prevention or treatment of osteonecrosis is recommendable at this moment.

Catalpol promotes the osteogenic differentiation of bone marrow mesenchymal stem cells via the Wnt/β-catenin pathway

Background

Rehmanniae Radix is a traditional herbal medicine in East Asia that has been widely used to treat patients with osteoporosis. However, the effect of catalpol, the primary active principle component of Rehmanniae Radix, on the function of bone marrow mesenchymal stem cells (BMSCs) and the underlying molecular mechanisms associated with its activity remain poorly understood.

Methods

The effect of catalpol on the proliferation of BMSCs was evaluated using a Cell Counting Kit-8 assay. Alkaline phosphatase (ALP) staining, ALP activity and Alizarin Red staining were performed to elucidate the effect of catalpol on the osteogenesis of BMSCs. qRT-PCR, Western blotting and immunofluorescence were performed to evaluate the expression of osteo-specific markers and the Wnt/β-catenin signalling-related genes and proteins. Moreover, a rat critical-sized calvarial defect model and a rat ovariectomy model were used to assess the effect of catalpol on bone regeneration in vivo.

Results

Catalpol significantly enhanced osteoblast-specific gene expression, alkaline phosphatase activity and calcium deposition in BMSCs in vitro. This phenomenon was accompanied by an upregulation of Wnt/β-catenin signalling. In addition, the enhanced osteogenesis due to catalpol treatment was partially reversed by a Wnt/β-catenin antagonist. Furthermore, catalpol increased the bone healing capacity of BMSCs in a rat critical-sized calvarial defect model and attenuated bone loss in a rat ovariectomy model.

Conclusions

These data suggest that catalpol enhances the osteogenic differentiation of BMSCs, partly via activation of the Wnt/β-catenin pathway. Catalpol may provide a new strategy for bone tissue engineering and can be a potential agent for the treatment of postmenopausal osteoporosis.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1143-y) contains supplementary material, which is available to authorized users.

The Prevention of Medication-related Osteonecrosis of the Jaw

BACKGROUND

Medication-related osteonecrosis of the jaw (MRONJ) is a preventable complication of antiresorptive treatment. It arises in 1-20% of patients with bone metastases of solid tumors and hematologic malignancies and in 0.1-2% of patients being treated for osteoporosis with bisphosphonates. Depending on the underlying disease and medication dosage, the risk of MRONJ can be elevated even in the first year of antiresorptive treatment. The treatment of MRONJ is difficult and often involves surgery of the jaw.

METHODS

We systematically reviewed publications retrieved by a selective search for literature on the prevention of MRONJ in the PubMed and Cochrane Library databases and with the aid of the Google Scholar search engine.

RESULTS

15 of 559 retrieved publications were included in the analysis. The quality of the evidence in the studies was generally moderate to low, with most of them being case series. In one case series of over 1200 patients with multiple myeloma, the incidence of MRONJ was lowered from 4.6% to 0.8% through regular dental checkups and improved oral hygiene. Tooth extraction, in particular, is associated with a high risk of MRONJ. In a retrospective study, 57% of patients who underwent tooth extraction without antibiotic prophylaxis developed MRONJ, compared to 0% with antibiotic prophylaxis.

CONCLUSION

Before antiresorptive medication is begun, oral hygiene should be improved. Moreover, it seems that perioperative antibiotic prophylaxis and adequate plastic wound closure can often prevent MRONJ. In view of the fact that bisphosphonates can persist in bone for more than 15 years, patients should be thoroughly informed of the risk that antiresorptive treatment can cause MRONJ, and the measures discussed should be initiated.

Bisphosphonate conjugation for bone specific drug targeting

Bones provide essential functions and are sites of unique biochemistry and specialized cells, but can also be sites of disease. The treatment of bone disorders and neoplasia has presented difficulties in the past, and improved delivery of drugs to bone remains an important goal for achieving effective treatments. Drug targeting strategies have improved drug localization to bone by taking advantage of the high mineral concentration unique to the bone hydroxyapatite matrix, as well as tissue-specific cell types. The bisphosphonate molecule class binds specifically to hydroxyapatite and inhibits osteoclast resorption of bone, providing direct treatment for degenerative bone disorders, and as emerging evidence suggests, cancer. These bone-binding molecules also provide the opportunity to deliver other drugs specifically to bone by bisphosphonate conjugation. Bisphosphonate bone-targeted therapies have been successful in treatment of osteoporosis, primary and metastatic neoplasms of the bone, and other bone disorders, as well as refining bone imaging. In this review, we focus upon the use of bisphosphonate conjugates with antineoplastic agents, and overview bisphosphonate based imaging agents, nanoparticles, and other drugs. We also discuss linker design potential and the current state of bisphosphonate conjugate research progress. Ongoing investigations continue to expand the possibilities for bone-targeted therapeutics and for extending their reach into clinical practice.

Inhibitory effects of CP on the growth of human gastric adenocarcinoma BGC-823 tumours in nude mice

Objective

To investigate the potential antitumour effects of [2-(6-amino-purine-9-yl)-1-hydroxy-phosphine acyl ethyl] phosphonic acid (CP) against gastric adenocarcinoma.

Methods

Human BGC-823 xenotransplants were established in nude mice. Animals were randomly divided into control and CP groups, which were administered NaHCO₃ vehicle alone or CP dissolved in NaHCO₃ (200 µg/kg body weight) daily, respectively. Tumour volume was measured weekly for 6 weeks. Resected tumours were assayed for proliferative activity with anti-Ki-67 or anti-proliferating cell nuclear antigen (PCNA) antibodies. Cell apoptosis was examined using terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assays and with caspase-3 immunostaining. Proteins were measured by Western blotting.

Results

There was a significant reduction in tumour volume and a reduced percentage of Ki-67-positive or PCNA-positive cells in the CP group compared with the control group. The percentage of TUNEL-positive or caspase 3-positive cells significantly increased following CP treatment compared with the control group. Tumours from the CP group had higher levels of phosphorylated-extracellular signal-regulated kinase (p-ERK) and phosphorylated-AKT (p-AKT) compared with control tumours.

Conclusion

CP treatment inhibited tumour growth and induced tumour cell apoptosis in a nude mouse model of BGC-823 gastric adenocarcinoma. Activation of the AKT and ERK signalling pathways may mediate this antitumour activity.

Calcium Phosphates as Delivery Systems for Bisphosphonates

Bisphosphonates (BPs) are the most utilized drugs for the treatment of osteoporosis, and are usefully employed also for other pathologies characterized by abnormally high bone resorption, including bone metastases. Due to the great affinity of these drugs for calcium ions, calcium phosphates are ideal delivery systems for local administration of BPs to bone, which is aimed to avoid/limit the undesirable side effects of their prolonged systemic use. Direct synthesis in aqueous medium and chemisorptions from solution are the two main routes proposed to synthesize BP functionalized calcium phosphates. The present review overviews the information acquired through the studies on the interaction between bisphosphonate molecules and calcium phosphates. Moreover, particular attention is addressed to some important recent achievements on the applications of BP functionalized calcium phosphates as biomaterials for bone substitution/repair.

Role of Periapical Diseases in Medication-Related Osteonecrosis of the Jaws

Objective

The present study aimed to investigate the role of periapical diseases in inducing medication-related osteonecrosis of the jaws (MRONJ) using an ovariectomized (OVX) mice model.

Materials and Methods

Twenty C57BL/6N female mice were randomly assigned to two groups. All mice were subjected to bilateral ovariectomy and then treated with oncologic dose of zoledronic acid (ZA) or vehicle for twelve weeks. Eight weeks after commence of drug administration, a pulpal exposure (PE) operation was performed on the first right lower molar to induce periapical periodontitis; the contralateral non-PE tooth was used as control. All animals were sacrificed four weeks after pulpal exposure, and the mandibles were harvested for radiological and histomorphometrical analysis.

Results

Micro computed tomography (μ-CT) examination demonstrated that periapical diseases significantly increased alveolar bone resorption, and the resorption was greatly attenuated by ZA treatment. Concurrent ZA therapy significantly increased bone density and histological osteocyte necrosis in the presence of periapical lesions.

Conclusion

ZA treatment reduced bone absorption resulting from periapical disease but increased the risk of developing MRONJ in the ovariectomized mouse model.

Identification of a vesicular ATP release inhibitor for the treatment of neuropathic and inflammatory pain

Despite the high incidence of neuropathic and inflammatory pain worldwide, effective drugs with few side effects are currently unavailable for the treatment of chronic pain. Recently, researchers have proposed that inhibitors of purinergic chemical transmission, which plays a key role in the pathological pain response, may allow for targeted treatment of pathological neuropathic and inflammatory pain. However, such therapeutic analgesic agents have yet to be developed. In the present study, we demonstrated that clodronate, a first-generation bisphosphonate with comparatively fewer side effects than traditional treatments, significantly attenuates neuropathic and inflammatory pain unrelated to bone abnormalities via inhibition of vesicular nucleotide transporter (VNUT), a key molecule for the initiation of purinergic chemical transmission. In vitro analyses indicated that clodronate inhibits VNUT at a half-maximal inhibitory concentration of 15.6 nM without affecting other vesicular neurotransmitter transporters, acting as an allosteric modulator through competition with Cl^- A low concentration of clodronate impaired vesicular ATP release from neurons, microglia, and immune cells. In vivo analyses revealed that clodronate is more effective than other therapeutic agents in attenuating neuropathic and inflammatory pain, as well as the accompanying inflammation, in wild-type but not VNUT ^-/- mice, without affecting basal nociception. These findings indicate that clodronate may represent a unique treatment strategy for chronic neuropathic and inflammatory pain via inhibition of vesicular ATP release.

Inflammatory Effects of Nitrogen-Containing Bisphosphonates (N-BPs): Modulation by Non-N-BPs

Bisphosphonates (BPs) are used against diseases with enhanced bone resorption. Those classed as nitrogen-containing BPs (N-BPs) exhibit much stronger anti-bone-resorptive effects than non-nitrogen-containing BPs (non-N-BPs). However, N-BPs carry the risk of inflammatory/necrotic side effects. Depending on their side-chains, BPs are divided structurally into cyclic and non-cyclic types. We previously found in mice that etidronate and clodronate (both non-cyclic non-N-BPs) could reduce the inflammatory effects of all three N-BPs tested (cyclic and non-cyclic types), possibly by inhibiting their entry into soft-tissue cells via SLC20 and/or SLC34 phosphate transporters. Tiludronate is the only available cyclic non-N-BP, but its effects on N-BPs' side effects have not been examined. Here, we compared the effects of etidronate, clodronate, and tiludronate on the inflammatory effects of six N-BPs used in Japan [three cyclic (risedronate, zoledronate, minodronate) and three non-cyclic (pamidronate, alendronate, ibandronate)]. Inflammatory effects were evaluated in mice by measuring the hind-paw-pad swelling induced by subcutaneous injection of an N-BP (either alone or mixed with a non-N-BP) into the hind-paw-pad. All of six N-BPs tested induced inflammation. Etidronate, clodronate, and the SLC20/34 inhibitor phosphonoformate inhibited this inflammation. Tiludronate inhibited the inflammatory effects of all N-BPs except ibandronate and minodronate, which have higher molecular weights than the other N-BPs. The mRNAs of SLC20a1, SLC20a2, and SLC34a2 (but not of SLC34a1 and SLC34a3) were detected in the soft-tissues of hind-paw-pads. These results suggest that etidronate, clodronate, and phosphonoformate may act non-selectively on phosphate transporter members, while tiludronate may not act on those transporting N-BPs of higher molecular weights.

Immobilization of alendronate on titanium via its different functional groups and the subsequent effects on cell functions

Immobilization of alendronate on orthopedic implants offers the possibility of enhancing osteogenesis without potentially adverse effects associated with systemic administration of this drug. In this work, alendronate was immobilized on titanium (Ti) via either its phosphate (Method 1) or amino (Method 2) groups, and responses of osteoblasts and human mesenchymal stem cells (hMSCs) on these surfaces were investigated. These modified substrates have similar surface roughness and are negatively charged. With similar amounts of immobilized alendronate, these two types of modified substrates showed comparable osteogenic stimulating effects in enhancing osteoblasts' alkaline phosphatase (ALP) activity and calcium deposition for the first 10days. However, alendronate immobilized via its phosphate groups was less stable, and gradually leached into the medium. As a result, its stimulating effect on osteoblast differentiation diminished with time. On the other hand, alendronate immobilized via its amino group stimulated osteoblast differentiation over 21days, and with 1655ng/cm2 of immobilized alendronate on the Ti substrate, calcium deposition by osteoblasts and hMSCs increased by 30% and 69%, respectively, compared to pristine Ti after 21days. The expressions of runt-related transcription factor 2, osterix, osteopontin and osteocalcin in hMSCs cultured on this substrate were monitored. The up-regulation of these genes is postulated to play a role in the acceleration of osteogenic differentiation of hMSCs cultured on the alendronate-modified substrate over those on pristine Ti.

The Bisphosphonates Clodronate and Etidronate Exert Analgesic Effects by Acting on Glutamate- and/or ATP-Related Pain Transmission Pathways

Bisphosphonates (BPs) are typical anti-bone-resorptive drugs, with nitrogen-containing BPs (N-BPs) being stronger than non-nitrogen-containing BPs (non-N-BPs). However, N-BPs have inflammatory/necrotic effects, while the non-N-BPs clodronate and etidronate lack such side effects. Pharmacological studies have suggested that clodronate and etidronate can (i) prevent the side effects of N-BPs in mice via inhibition of the phosphate transporter families SLC20 and/or SLC34, through which N-BPs enter soft-tissue cells, and (ii) also inhibit the phosphate transporter family SLC17. Vesicular transporters for the pain transmitters glutamate and ATP belong to the SLC17 family. Here, we examined the hypothesis that clodronate and etidronate may enter neurons through SLC20/34, then inhibit SLC17-mediated transport of glutamate and/or ATP, resulting in their decrease, and thereby produce analgesic effects. We analyzed in mice the effects of various agents [namely, intrathecally injected clodronate, etidronate, phosphonoformic acid (PFA; an inhibitor of SLC20/34), and agonists of glutamate and ATP receptors] on the nociceptive responses to intraplantar injection of capsaicin. Clodronate and etidronate produced analgesic effects, and these effects were abolished by PFA. The analgesic effects were reduced by N-methyl-D-aspartate (agonist of the NMDA receptor, a glutamate receptor) and α,β-methylene ATP (agonist of the P2X-receptor, an ATP receptor). SLC20A1, SLC20A2, and SLC34A1 were detected within the mouse lumbar spinal cord. Although we need direct evidence, these results support the above hypothesis. Clodronate and etidronate may be representatives of a new type of analgesic drug. Such drugs, with both anti-bone-resorptive and unique analgesic effects without the adverse effects associated with N-BPs, might be useful for osteoporosis.

NF-κB as a Therapeutic Target in Inflammatory-Associated Bone Diseases

Inflammation is a defensive mechanism for pathogen clearance and maintaining tissue homeostasis. In the skeletal system, inflammation is closely associated with many bone disorders including fractures, nonunions, periprosthetic osteolysis (bone loss around orthopedic implants), and osteoporosis. Acute inflammation is a critical step for proper bone-healing and bone-remodeling processes. On the other hand, chronic inflammation with excessive proinflammatory cytokines disrupts the balance of skeletal homeostasis involving osteoblastic (bone formation) and osteoclastic (bone resorption) activities. NF-κB is a transcriptional factor that regulates the inflammatory response and bone-remodeling processes in both bone-forming and bone-resorption cells. In vitro and in vivo evidences suggest that NF-κB is an important potential therapeutic target for inflammation-associated bone disorders by modulating inflammation and bone-remodeling process simultaneously. The challenges of NF-κB-targeting therapy in bone disorders include: (1) the complexity of canonical and noncanonical NF-κB pathways; (2) the fundamental roles of NF-κB-mediated signaling for bone regeneration at earlier phases of tissue damage and acute inflammation; and (3) the potential toxic effects on nontargeted cells such as lymphocytes. Recent developments of novel inhibitors with differential approaches to modulate NF-κB activity, and the controlled release (local) or bone-targeting drug delivery (systemic) strategies, have largely increased the translational application of NF-κB therapy in bone disorders. Taken together, temporal modulation of NF-κB pathways with the combination of recent advanced bone-targeting drug delivery techniques is a highly translational strategy to reestablish homeostasis in the skeletal system.

Novel therapeutic intervention for osteoporosis prepared with strontium hydroxyapatite and zoledronic acid: In vitro and pharmacodynamic evaluation

Osteoporosis therapeutics has been monopolized mainly by bisphosphonates, which are potent anti-osteoporotic drugs, while they do not promote bone formation or replenish the already resorbed bone. Although strontium substituted hydroxyapatite (SrHA) has been proclaimed to improve bone properties in an osteoporotic animal model, there is no published data on direct delivery of SrHA nanoparticles by bisphosphonate-like zoledronic acid (ZOL) to the bone. Therefore, this study was designed to investigate the potential of using SrHA/ZOL nanoparticle-based drug formulation in an ovariectomized rat model of postmenopausal osteoporosis. SrHA and SrHA/ZOL nanoparticles were prepared and characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Twelve weeks after ovariectomy, rats were treated with either single intravenous dose of SrHA/ZOL (100, 50 or 25μg/kg); ZOL (100μg/kg); or SrHA (100μg/kg). Saline-treated OVX and SHAM-OVX groups served as controls. The energy-dispersive X-ray (EDX) microanalysis of bone specimen obtained from SrHA/ZOL groups yielded range between 64.3±6.7 to 66.9±6.8 of calcium weight (wt) % and 1.64±0.6 to 1.74±0.8 of calcium/phosphorus (Ca/P) ratio which was significantly higher when compared with 39.7±9.3 calcium and 1.30±0.2 Ca/P ratio for OVX group. Moreover, the strontium wt% in SrHA/ZOL group (between 3.1±0.5 and 6.8±0.4) was significantly higher than SrHA group (1.8±0.9). These results confirmed targeted delivery of SrHA nanoparticles by ZOL to the bone. Therapy with SrHA/ZOL showed significant improvements in trabecular bone microarchitecture and mechanical strength as compared to ZOL or SrHA (p<0.05). Moreover, treatment with SrHA/ZOL significantly precluded an increase in serum bone-specific alkaline phosphatase and tartrate-resistant acid phosphatase than either ZOL or SrHA (p<0.05). These results strongly implicate that SrHA/ZOL nanoparticle-based drug formulation showed better efficacy at a much lower dose of ZOL. SrHA/ZOL drug formulation has a therapeutic advantage over ZOL or SrHA monotherapy for experimental osteoporosis.

Bisphosphonates for steroid-induced osteoporosis

BACKGROUND

This is an update of a Cochrane Review first published in 1999. Corticosteroids are widely used in inflammatory conditions as an immunosuppressive agent. Bone loss is a serious side effect of this therapy. Several studies have examined the use of bisphosphonates in the prevention and treatment of glucocorticosteroid-induced osteoporosis (GIOP) and have reported varying magnitudes of effect.

OBJECTIVES

To assess the benefits and harms of bisphosphonates for the prevention and treatment of GIOP in adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE and Embase up to April 2016 and International Pharmaceutical Abstracts (IPA) via OVID up to January 2012 for relevant articles and conference proceedings with no language restrictions. We searched two clinical trial registries for ongoing and recently completed studies (ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) search portal). We also reviewed reference lists of relevant review articles.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) satisfying the following criteria: 1) prevention or treatment of GIOP; 2) adults taking a mean steroid dose of 5.0 mg/day or more; 3) active treatment including bisphosphonates of any type alone or in combination with calcium or vitamin D; 4) comparator treatment including a control of calcium or vitamin D, or both, alone or with placebo; and 4) reporting relevant outcomes. We excluded trials that included people with transplant-associated steroid use.

DATA COLLECTION AND ANALYSIS

At least two review authors independently selected trials for inclusion, extracted data, performed 'risk of bias' assessment and evaluated the certainty of evidence using the GRADE approach. Major outcomes of interest were the incidence of vertebral and nonvertebral fractures after 12 to 24 months; the change in bone mineral density (BMD) at the lumbar spine and femoral neck after 12 months; serious adverse events; withdrawals due to adverse events; and quality of life. We used standard Cochrane methodological procedures.

MAIN RESULTS

We included a total of 27 RCTs with 3075 participants in the review. Pooled analysis for incident vertebral fractures included 12 trials (1343 participants) with high-certainty evidence and low risk of bias. In this analysis 46/597 (or 77 per 1000) people experienced new vertebral fractures in the control group compared with 31/746 (or 44 per 1000; range 27 to 70) in the bisphosphonate group; relative improvement of 43% (9% to 65% better) with bisphosphonates; absolute increased benefit of 2% fewer people sustaining fractures with bisphosphonates (5% fewer to 1% more); number needed to treat for an additional beneficial outcome (NNTB) was 31 (20 to 145) meaning that approximately 31 people would need to be treated with bisphosphonates to prevent new vertebral fractures in one person.Pooled analysis for incident nonvertebral fractures included nine trials with 1245 participants with low-certainty evidence (downgraded for imprecision and serious risk of bias as a patient-reported outcome). In this analysis 30/546 (or 55 per 1000) people experienced new nonvertebral fracture in the control group compared with 29/699 (or 42 per 1000; range 25 to 69) in the bisphosphonate group; relative improvement of 21% with bisphosphonates (33% worse to 53% better); absolute increased benefit of 1% fewer people with fractures with bisphosphonates (4% fewer to 1% more).Pooled analysis on BMD change at the lumbar spine after 12 months included 23 trials with 2042 patients. Eighteen trials with 1665 participants were included in the pooled analysis on BMD at the femoral neck after 12 months. Evidence for both outcomes was moderate-certainty (downgraded for indirectness as a surrogate marker for osteoporosis) with low risk of bias. Overall, the bisphosphonate groups reported stabilisation or increase in BMD, while the control groups showed decreased BMD over the study period. At the lumbar spine, there was an absolute increase in BMD of 3.5% with bisphosphonates (2.90% to 4.10% higher) with a relative improvement of 1.10% with bisphosphonates (0.91% to 1.29%); NNTB 3 (2 to 3). At the femoral neck, the absolute difference in BMD was 2.06% higher in the bisphosphonate group compared to the control group (1.45% to 2.68% higher) with a relative improvement of 1.29% (0.91% to 1.69%); NNTB 5 (4 to 7).Pooled analysis on serious adverse events included 15 trials (1703 participants) with low-certainty evidence (downgraded for imprecision and risk of bias). In this analysis 131/811 (or 162 per 1000) people experienced serious adverse events in the control group compared to 136/892 (or 147 per 1000; range 120 to 181) in the bisphosphonate group; absolute increased harm of 0% more serious adverse events (2% fewer to 2% more); a relative per cent change with 9% improvement (12% worse to 26% better).Pooled analysis for withdrawals due to adverse events included 15 trials (1790 patients) with low-certainty evidence (downgraded for imprecision and risk of bias). In this analysis 63/866 (or 73 per 1000) people withdrew in the control group compared to 76/924 (or 77 per 1000; range 56 to 107) in the bisphosphonate group; an absolute increased harm of 1% more withdrawals with bisphosphonates (95% CI 1% fewer to 3% more); a relative per cent change 6% worse (95% CI 47% worse to 23% better).Quality of life was not assessed in any of the trials.

AUTHORS' CONCLUSIONS

There was high-certainty evidence that bisphosphonates are beneficial in reducing the risk of vertebral fractures with data extending to 24 months of use. There was low-certainty evidence that bisphosphonates may make little or no difference in preventing nonvertebral fractures. There was moderate-certainty evidence that bisphosphonates are beneficial in preventing and treating corticosteroid-induced bone loss at both the lumbar spine and femoral neck. Regarding harm, there was low-certainty evidence that bisphosphonates may make little or no difference in the occurrence of serious adverse events or withdrawals due to adverse events. We are cautious in interpreting these data as markers for harm and tolerability due to the potential for bias.Overall, our review supports the use of bisphosphonates to reduce the risk of vertebral fractures and the prevention and treatment of steroid-induced bone loss.

Wedelolactone enhances osteoblastogenesis by regulating Wnt/β-catenin signaling pathway but suppresses osteoclastogenesis by NF-κB/c-fos/NFATc1 pathway

Bone homeostasis is maintained by formation and destruction of bone, which are two processes tightly coupled and controlled. Targeting both stimulation on bone formation and suppression on bone resorption becomes a promising strategy for treating osteoporosis. In this study, we examined the effect of wedelolactone, a natural product from Ecliptae herba, on osteoblastogenesis as well as osteoclastogenesis. In mouse bone marrow mesenchymal stem cells (BMSC), wedelolactone stimulated osteoblast differentiation and bone mineralization. At the molecular level, wedelolactone directly inhibited GSK3β activity and enhanced the phosphorylation of GSK3β, thereafter stimulated the nuclear translocation of β-catenin and runx2. The expression of osteoblastogenesis-related marker gene including osteorix, osteocalcin and runx2 increased. At the same concentration range, wedelolactone inhibited RANKL-induced preosteoclastic RAW264.7 actin-ring formation and bone resorption pits. Further, wedelolactone blocked NF-kB/p65 phosphorylation and abrogated the NFATc1 nuclear translocation. As a result, osteoclastogenesis-related marker gene expression decreased, including c-src, c-fos, and cathepsin K. In ovariectomized mice, administration of wedelolactone prevented ovariectomy-induced bone loss by enhancing osteoblast activity and inhibiting osteoclast activity. Together, these data demonstrated that wedelolactone facilitated osteoblastogenesis through Wnt/GSK3β/β-catenin signaling pathway and suppressed RANKL-induced osteoclastogenesis through NF-κB/c-fos/NFATc1 pathway. These results suggested that wedelolacone could be a novel dual functional therapeutic agent for osteoporosis.

Ethanol Extract of Cissus quadrangularis Enhances Osteoblast Differentiation and Mineralization of Murine Pre-Osteoblastic MC3T3-E1 Cells

Traditional medicinal literature and previous studies have reported the possible role of Cissus quadrangularis (CQ) as an anti-osteoporotic agent. This study examines the effectiveness of CQ in promoting osteoblast differentiation of the murine pre-osteoblast cell line, MC3T3-E1. Ethanolic extract of CQ (CQ-E) was found to affect growth kinetics of MC3T3-E1 cells in a dosage-dependent manner. High concentrations of CQ-E (more than 10 μg/ml) have particularly adverse effects, while lower concentrations of 0.1 and 1 µg/ml were non-toxic and did not affect cell viability. Notably, cell proliferation was significantly increased at the lower concentrations of CQ-E. CQ-E treatment also augmented osteoblast differentiation, as reflected by a substantial increase in expression of the early osteoblast marker ALP activity, and at later stage, by mineralization of extracellular matrix compared to the control group. These findings suggest dose-dependent effect of CQ-E with lower concentrations exhibiting anabolic and osteogenic properties. J. Cell. Physiol. 232: 540-547, 2017. © 2016 Wiley Periodicals, Inc.