Effects of intravenous zoledronic acid once yearly on bone remodeling and bone structure

Evaluation of Osteogenic Phenotype in Postmenopausal Women Receiving Anabolic and Antiresorptive Osteoporosis Therapies

Aging of the general population has led to a substantial increase in the prevalence of osteoporosis over the past decades. While there are effective pharmacological agents that increase bone formation, decrease bone resorption, and decrease fracture risk, they do not uniformly cure osteoporosis. This has prompted investigations to examine whether combination therapy (COMBO) with these agents can result in an additive benefit. Since concomitant therapy with denosumab and teriparatide has shown promise in this respect, investigations were undertaken to explore whether the changes in osteogenic phenotype could provide insight into the cellular and molecular mechanism of this effect. Investigations were performed in postmenopausal women receiving denosumab, teriparatide, or both for 3 months. Histomorphometric parameters were the primary outcome, while exploratory studies examined RNA expression in bone biopsies as well as in sorted and cultured bone marrow stromal cells (BMSCs). Osteogenic colony forming units of BMSCs were also evaluated. The studies demonstrated that COMBO results in an increase in osteoprogenitors, evidenced by an increase in osteoblastic colony-forming units. This was associated with an increased in BMSC expression of LGR6 (leucine-rich repeat containing G protein-coupled receptor 6), a stem cell marker and activator of the canonical Wnt signaling pathway. These data suggest that enhancement of canonical Wnt signaling contributes to the increase in osteoprogenitors and consequently an increase in bone density in postmenopausal women receiving COMBO for osteoporosis.

Effects of tibolone combined with zoledronic acid on bone density, bone metabolism, and pain in postmenopausal patients with osteoporosis

OBJECTIVE

To explore the efficacy and safety of tibolone combined with zoledronic acid in the treatment of postmenopausal osteoporosis (PMO).

METHODS

We conducted a retrospective analysis of 121 PMO patients from March 2019 to July 2021. Patients were divided into two groups based on treatment regimen: an observation group (n=62) receiving zoledronic acid combined with tibolone and a control group (n=59) receiving tibolone monotherapy. We evaluated and compared therapeutic efficacy, bone mineral density, bone metabolism markers (osteocalcin, serum C-terminal telopeptide of type I collagen, and bone alkaline phosphatase), pain, knee joint function, incidence of fragility fractures, and adverse reactions. Logistic regression analysis was used to evaluate risk factors affecting treatment efficacy.

RESULTS

The observation group showed a significantly higher therapeutic effect (96.77%) compared to the control group (83.05%), and a lower incidence of fragility fractures (P=0.012). Before treatment, there were no significant differences in bone mineral density, bone metabolism markers, pain status, or knee function between the two groups (all P>0.05). However, after treatment, evaluations showed marked improvements in these parameters in both groups, with more significant enhancements observed in the observation group (all P<0.001). The incidence of adverse reactions did not significantly differ between the groups (20.97% vs 13.56%, P=0.282). Logistic regression analysis identified the use of tibolone combined with zoledronic acid as a protective factor for effective treatment.

CONCLUSIONS

Tibolone combined with zoledronic acid significantly increases bone mineral density, improves bone metabolism, and reduces pain in PMO patients, with a safety profile comparable to that of monotherapy. This regimen should be considered for clinical use in treating PMO.

Differences in bone histomorphometry between White postmenopausal women with and without atypical femoral fracture after long-term bisphosphonate therapy

Bone histomorphometric endpoints in transilial biopsies may be associated with an increased risk of atypical femoral fracture (AFF) in patients with osteoporosis who take antiresorptives, including bisphosphonates (BPs). One way to test this hypothesis is to evaluate bone histomorphometric endpoints in age-, gender-, and treatment time-matched patients who either had AFF or did not have AFF. In this study, we performed transiliac bone biopsies in 52 White postmenopausal women with (n = 20) and without (n = 32) AFFs, all of whom had been treated for osteoporosis continuously with alendronate for 4-17 yr. Despite the matched range of treatment duration (4-17 yr), AFF patients received alendronate for significantly longer time (10.7 yr) than non-AFF patients (8.0 yr) (P = .014). Bone histomorphometric endpoints reflecting microstructure and turnover were assessed in cancellous, intracortical, and endocortical envelopes from transilial biopsy specimens obtained from BP-treated patients 3-6 mo after AFF and from non-AFF patients with similar age-, gender-, and range of BP treatment duration. However, in both cancellous and intracortical envelopes, AFF patients had significantly lower wall thickness (W.Th) and higher osteoclast surface (Oc.S/BS) than non-AFF patients. In addition, AFF patients had significantly higher eroded surface (ES/BS) only in the intracortical envelope. None of the dynamic variables related to bone formation and turnover differed significantly between the groups. In conclusion, in the ilium of BP-treated patients with osteoporosis, AFF patients have lower thickness of superficial bone (lower W.Th) of the cancellous and cortical envelopes than non-AFF patients. AFF and non-AFF patients have a similar bone turnover rate in the ilium. Furthermore, in this population, as in previous work, AFF is more likely to occur in BP-treated patients with longer treatment duration.

Osteoimmunology: The Crosstalk between T Cells, B Cells, and Osteoclasts in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an ongoing inflammatory condition that affects the joints and can lead to severe damage to cartilage and bones, resulting in significant disability. This condition occurs when the immune system becomes overactive, causing osteoclasts, cells responsible for breaking down bone, to become more active than necessary, leading to bone breakdown. RA disrupts the equilibrium between osteoclasts and osteoblasts, resulting in serious complications such as localized bone erosion, weakened bones surrounding the joints, and even widespread osteoporosis. Antibodies against the receptor activator of nuclear factor-κB ligand (RANKL), a crucial stimulator of osteoclast differentiation, have shown great effectiveness both in laboratory settings and actual patient cases. Researchers are increasingly focusing on osteoclasts as significant contributors to bone erosion in RA. Given that RA involves an overactive immune system, T cells and B cells play a pivotal role by intensifying the immune response. The imbalance between Th17 cells and Treg cells, premature aging of T cells, and excessive production of antibodies by B cells not only exacerbate inflammation but also accelerate bone destruction. Understanding the connection between the immune system and osteoclasts is crucial for comprehending the impact of RA on bone health. By delving into the immune mechanisms that lead to joint damage, exploring the interactions between the immune system and osteoclasts, and investigating new biomarkers for RA, we can significantly improve early diagnosis, treatment, and prognosis of this condition.

Alterations in macrophage polarization in the craniofacial and extracranial skeleton after zoledronate application and surgical interventions - an in vivo experiment

Purpose

Medication-related osteonecrosis occurs exclusively in the jaw bones. However, the exact pathogenesis of medication-related osteonecrosis of the jaw (MRONJ) and the unique predisposition of the jaw bones have not been elucidated, making its treatment a challenge. Recent evidence indicates that macrophages might play a pivotal role in MRONJ pathogenesis. The aim of the present study was to compare the macrophage populations between the craniofacial and extracranial skeleton and to investigate the changes induced by zoledronate (Zol) application and surgical interventions.

Materials and methods

An in vivo experiment was performed. 120 wistar rats were randomized to 4 groups (G1, G2, G3, G4). G1 served as an untreated control group. G2 and G4 received Zol injections for 8 weeks. Afterwards, the right lower molar of the animals from G3 and G4 was extracted and the right tibia osteotomized followed by osteosynthesis. Tissue samples were taken from the extraction socket and the tibia fracture at fixed time points. Immunohistochemistry was conducted to determine the labeling indexes of CD68+ and CD163+ macrophages.

Results

Comparing the mandible and the tibia, we observed a significantly higher number of macrophages and a heightened pro-inflammatory environment in the mandible compared to the tibia. Tooth extraction caused an increase of the overall number of macrophages and a shift toward a more pro-inflammatory microenvironment in the mandible. Zol application amplified this effect.

Conclusion

Our results indicate fundamental immunological differences between the jaw bone and the tibia, which might be a reason for the unique predisposition for MRONJ in the jaw bones. The more pro-inflammatory environment after Zol application and tooth extraction might contribute to the pathogenesis of MRONJ. Targeting macrophages might represent an attractive strategy to prevent MRONJ and improve therapy. In addition, our results support the hypothesis of an anti-tumoral and anti-metastatic effect induced by BPs. However, further studies are needed to delineate the mechanisms and specify the contributions of the various macrophage phenotypes.

Twelve Months of Denosumab and/or Alendronate Is Associated With Improved Bone Fatigue Life, Microarchitecture, and Density in Ovariectomized Cynomolgus Monkeys

Prolonged use of antiresorptives such as the bisphosphonate alendronate (ALN) and the RANKL inhibitor denosumab (DMAb) are associated with rare cases of atypical femoral fracture (AFF). The etiology of AFF is unclear, but it has been hypothesized that potent osteoclast inhibitors may reduce bone fatigue resistance. The purpose of this study was to quantify the relationship between antiresorptive treatment and fatigue life (cycles to failure) in bone from ovariectomized cynomolgus monkeys. We analyzed humeral bone from 30 animals across five treatment groups. Animals were treated for 12 months with subcutaneous (sc) vehicle (VEH), sc DMAb (25 mg/kg/month), or intravenous (iv) ALN (50 μg/kg/month). Another group received 6 months VEH followed by 6 months DMAb (VEH-DMAb), and the final group received 6 months ALN followed by 6 months DMAb (ALN-DMAb). A total of 240 cortical beam samples were cyclically tested in four-point bending at 80, 100, 120, or 140 MPa peak stress. High-resolution imaging and density measurements were performed to evaluate bone microstructure and composition. Samples from the ALN (p = 0.014), ALN-DMAb (p = 0.008), and DMAb (p < 0.001) groups illustrated higher fatigue-life measurements than VEH. For example, at 140 MPa the VEH group demonstrated a median ± interquartile range (IQR) fatigue life of 1987 ± 10593 cycles, while animals in the ALN, ALN-DMAb, and DMAb groups survived 9850 ± 13648 (+395% versus VEH), 10493 ± 16796 (+428%), and 14495 ± 49299 (+629%) cycles, respectively. All antiresorptive treatment groups demonstrated lower porosity, smaller pore size, greater pore spacing, and lower number of canals versus VEH (p < 0.001). Antiresorptive treatment was also associated with greater apparent density, dry density, and ash density (p ≤ 0.03). We did not detect detrimental changes following antiresorptive treatments that would explain their association with AFF. In contrast, 12 months of treatment may have a protective effect against fatigue fractures. © 2022 American Society for Bone and Mineral Research (ASBMR).

Effect of Mechanical Stimuli and Zoledronic Acid on the Femoral Bone Morphology in Rats with Obesity and Limited Mobility

Our study aimed to compare the impact of zoledronic acid and whole-body vibration (WBV) as a non-pharmacological method of treatment for early obesity/immobility-related osteoporosis in male rat models. In total, 36 male Wistar rats were assigned to the following groups: obese control with immobility (Control, n = 12) and two experimental groups (n = 12 each), including obese and immobile rats subjected to whole-body vibration with an acceleration level of 3 m/s² g (obesity and immobility + WBV) and obese and immobile rats that received an intramuscular injection of zoledronic acid at a dose of 0.025 mg/kg (obesity and immobility + ZOL). After the 8th and 16th week of treatment, n = 6 rats from each group were euthanized and isolated femora were subjected to a histological examination of bone, and analysis of the expression of osteoprotegerin (OPG) and the receptor activator of nuclear factor kappa-B ligand (RANKL) involved in bone turnover and the amount of thin collagen fibers (PSR stain). The obtained results showed that short-term vibrotherapy (up to 8 weeks) can lead to improvement in bone remodeling in rat models with obesity and limited mobility.

Risk factors for new vertebral compression fracture after kyphoplasty and efficacy of osteoporosis treatment: A STROBE-compliant retrospective study

Kyphoplasty (KP) has been widely used to treat vertebral compression fractures (VCFs). However, the issue of new VCFs after KP remains controversial. Identification of risk factors for new VCF after KP may help prevent their occurrence in patients. This study aimed to retrospectively determine the major risk factors for new VCF after KP, including those associated with osteoporosis drugs used after kyphoplasty. We reviewed 117 patients who underwent single-level KP. During the follow-up period of 1 year after KP, the demographic data of these patients were compared by dividing them into two groups: those with new fractures (n = 19) and those without new fractures (n = 98). We investigated the age, sex, fracture location, medical history, steroid use history, bone mineral density (BMD), type of osteoporosis treatment, period from fracture to KP, KP method (unilateral or bilateral), bone cement dose, intradiscal cement leakage, preoperative and postoperative compression ratio, kyphotic angle (KA), and lowest vertebral body height in the fractured vertebrae. Based on these data, the factors related to new VCFs after KP were investigated using univariate and multivariate logistic regression analyses. We also investigated whether there were differences in new VCFs according to the type of osteoporosis treatment. During the 1-year follow-up period after KP, the rate of new VCFs was 16.2%. Factors related to new VCFs were BMD, intradiscal cement leakage, KA recovery rate after 1 day, and baseline height in the univariate and multivariate logistic regression analyses. The group treated with zoledronate after KP tended to show a lower frequency of developing new VCFs than the groups treated with alendronate (P = .07), calcium (P = .05), selective estrogen receptor modulator (SERM) (P = .15), and risendronate (P = .02). This study showed that for patients with new VCFs after KP, lower BMD, greater intradiscal cement leakage, greater KA recovery rate, and lower baseline vertebral height were likely risk factors for the development of new VCFs. Additionally, among the drugs used for the treatment of osteoporosis after KP, zoledronate tends to reduce the development of new VCFs compared with other bisphosphonates, SERMs, or calcium.

Clinical efficacy of bisphosphonates and monoclonal antibodies on bone mineral density following skeletal fractures

Background

Bisphosphonates and monoclonal antibodies are drugs primarily developed to inhibit osteoclast-mediated bone resorption and are used to treat an array of skeletal pathologies. Their use is aimed at increasing bone health and therefore reducing fracture risks. The aim of this study was to evaluate the effectiveness of bone protection therapy on improving bone mineral density (BMD) in patients following a fracture.

Methods

Inclusion criteria consisted of patients who sustained a skeletal fracture and were subsequently commenced on bone protection therapy. Dual-energy X-ray Absorptiometry (DEXA) scans were performed at baseline and following a consented period of drug therapy. Bone health data included T-Scores, Z-Scores, FRAX Major, FRAX Hip and BMD. The clinical effectiveness of four bisphosphonates (alendronate, risedronate, pamidronate and zoledronate) and one monoclonal antibody (denosumab) were evaluated.

Results

A total of 100 patients were included in the study. Overall, bone protection therapy significantly improved Z-score Hip, Z-score Spine, T-score Spine and BMD Spine (p < 0.05). There was a marked difference between drug therapies. Denosumab and zoledronate were associated with the greatest treatment effect size. Alendronate only improved Z-score Spine and Z-score Hip (p < 0.05). Pamidronate and risedronate did not demonstrate any statistically significant improvement across any DEXA parameter.

Conclusion

Overall, bisphosphonates/monoclonal antibodies confer beneficial effects on bone health as measured by DEXA scans in patients following skeletal fractures. However, the magnitude of improvement varies among the commonly used drugs. Alendronate, zoledronate and denosumab were associated with greatest therapeutic benefit. Bone protection therapy did not improve fracture risk of patients (FRAX scores).

Treatment of postmenopausal osteoporosis patients with teriparatide for 24 months reverts forming bone quality indices to premenopausal healthy control values

Postmenopausal osteoporosis (PMOP) therapies are frequently evaluated by bone mineral density (BMD) gains against patients receiving placebo (calcium and vitamin D supplementation, a mild bone turnover-suppressing intervention), which is not equivalent to either healthy or treatment-naive PMOP. The aim of the present observational study was to assess the effects of TPTD treatment in PMOP (20 μg, once daily) at 6 (TPTD 6m; n = 28, age 65 ± 7.3 years), and 24 (TPTD 24m; n = 32, age 67.4 ± 6.15 years) months on bone quality indices at actively forming trabecular surfaces (with fluorescent double labels). Data from the TPTD-treated PMOP patients were compared with those in healthy adult premenopausal women (HC; n = 62, age 40.5 ± 10.6 years), and PMOP receiving placebo (PMOP-PLC; n = 94, age 70.6 ± 4.5 years). Iliac crest biopsies were analyzed by Raman microspectroscopy at three distinct tissue ages: mid-distance between the second label and the bone surface, mid-distance between the two labels, and 1 μm behind the first label. Mineral to matrix ratio (MM), mineral maturity/crystallinity (MMC), tissue water (TW), glycosaminoglycan (GAGs), and pyridinoline (Pyd) content were determined. Outcomes were compared by ANCOVA with subject age and tissue age as covariates, and health status as a fixed factor, followed by Sidak's post-hoc testing (significance assigned to p < 0.05). Both TPTD groups increased MM compared to PMOP-PLC. While TPTD 6m had values similar to HC, TPTD 24m had higher values compared to either HC or TPTD 6m. Both TPTD groups had lower MMC values compared to PMOP-PLC and similar to HC. TPTD 6m patients had higher TW content compared to HC, while TPTD 24m had values similar to HC and lower than either PMOP-PLC or TPTD 6m. Both TPTD groups had lower GAG content compared to HC group, while TPTD 6m had higher values compared to PMOP-PLC. Finally, TPTD 6m patients had higher Pyd content compared to HC and lower compared to PMOP-PLC, while TPTD 24m had lower values compared to PMOP-PLC and TPTD 6m, and similar to HC group. The results of the present study indicate that effects of TPTD on forming trabecular bone quality indices depend on treatment duration. At the recommended length of 24 m, TPTD restores bone mineral and organic matrix quality indices (MMC, TW, Pyd content) to premenopausal healthy (HC) levels.

High-Intensity Exercise and Geometric Indices of Hip Bone Strength in Postmenopausal Women on or off Bone Medication: The MEDEX-OP Randomised Controlled Trial

To compare the effects of high-intensity resistance and impact training (HiRIT) to low-intensity, Pilates-based exercise (LiPBE) on proximal femur geometry and explore the influence of antiresorptive medication on those effects. Postmenopausal women with low bone mass, on or off antiresorptive bone medications were randomly allocated, stratified on medication intake, to eight months of twice-weekly, supervised HiRIT (Onero™) or LiPBE (Buff Bones®). 3D hip software was used to analyse proximal femur DXA scans. Outcomes included femoral neck (FN) and total hip (TH), volumetric (e.g. vBMC, vBMD) and geometric (e.g. cortical thickness, cross-sectional area [CSA], section modulus [Z]) indices of bone strength. Data were analysed using analysis of variance. Scans of 102 women were examined: LiPBE, 43; HiRIT, 37; LiPBE-med, 11; HiRIT-med, 11. HiRIT improved TH trabecular vBMC and vBMD (3.1 ± 1.1% versus - 1.2 ± 1.2%, p = 0.008; and 1.5 ± 1.0% versus - 1.6 ± 1.2%, p = 0.042, respectively) and FN and TH total vBMC (2.0 ± 0.8% versus - 0.2 ± 0.7%, p = 0.032; and 0.7 ± 0.4% versus - 0.8 ± 0.6%, p = 0.032, respectively), compared to losses in LiPBE. HiRIT also increased Z while LiPBE did not (p = 0.035). The combination of HiRIT and medication achieved greater improvements in FN total and trabecular vBMD, total BMC, CSA and Z than HiRIT alone. HiRIT improved geometric parameters of proximal femur strength, while LiPBE exercise was largely ineffective. Medication may enhance some HiRIT effects. Findings suggest reduced hip fracture risk in response to HiRIT.Trial registration number ACTRN12617001511325.

Interest of Bone Histomorphometry in Bone Pathophysiology Investigation: Foundation, Present, and Future

Despite the development of non-invasive methods, bone histomorphometry remains the only method to analyze bone at the tissue and cell levels. Quantitative analysis of transiliac bone sections requires strict methodologic conditions but since its foundation more 60 years ago, this methodology has progressed. Our purpose was to review the evolution of bone histomorphometry over the years and its contribution to the knowledge of bone tissue metabolism under normal and pathological conditions and the understanding of the action mechanisms of therapeutic drugs in humans. The two main applications of bone histomorphometry are the diagnosis of bone diseases and research. It is warranted for the diagnosis of mineralization defects as in osteomalacia, of other causes of osteoporosis as bone mastocytosis, or the classification of renal osteodystrophy. Bone biopsies are required in clinical trials to evaluate the safety and mechanism of action of new therapeutic agents and were applied to anti-osteoporotic agents such as bisphosphonates and denosumab, an anti-RANKL, which induces a marked reduction of the bone turnover with a consequent elongation of the mineralization period. In contrast, an increased bone turnover with an extension of the formation site is observed with teriparatide. Romosozumab, an anti-sclerostin, has a dual effect with an early increased formation and reduced resorption. Bone histomorphometric studies allow us to understand the mechanism of coupling between formation and resorption and to evaluate the respective role of bone modeling and remodeling. The adaptation of new image analysis techniques will help bone biopsy analysis in the future.

Alendronate prolongs the reversal-resorption phase in human cortical bone remodeling

Despite their ability to reduce fracture-risk and increase Bone Mineral Density (BMD) in osteoporotic women, bisphosphonates are reported to reduce formation of new bone. Reduced bone formation has been suggested to lead to accumulation of microfractures and contribute to rare side effects in cortical bone such as atypical femur fractures. However, most studies are limited to trabecular bone. In this study, the cortical bone remodeling in human iliac bone specimens of 65 non-treated and 24 alendronate-treated osteoporotic women was investigated using a new histomorphometric classification of intracortical pores. The study showed that only 12.4 ± 11% of the cortical pore area reflected quiescent pores/osteons in alendronate-treated patients versus 8.5 ± 5% in placebo, highlighting that new cortical remodeling events remain to be activated. The percent and size of eroded pores (events in resorption-reversal phase) remained unchanged, but their contribution to total pore area was 1.4-fold higher in alendronate versus placebo treated patients (66 ± 22% vs 48 ± 22%, p < 0.001). On the other hand, the mixed eroded-formative pores (events with mixed resorption-reversal-formation phases) was 2-fold lower in alendronate versus placebo treated patients (19 ± 14% vs 39 ± 23% of total pore area, p < 0.001), and formative pores (event in formation phase) was 2.2-fold lower in alendronate versus placebo treated patients (2.1 ± 2.4% vs 4.6 ± 3.6%, p < 0.01), and their contribution to total pore area was 2.4-fold lower (1.3 ± 2.1% vs 3.1 ± 4.4%, p < 0.05). Importantly, these differences between alendronate and placebo treated patients were significant in patients after 3 years of treatment, not after 2 years of treatment. Collectively, the results support that cortical remodeling events activated during alendronate treatment has a prolonged reversal-resorption phase with a delayed transition to formation, becoming increasingly evident after 3-years of treatment. A potential contributor to atypical femur fractures associated with long-term bisphosphonate treatment.

Bisphosphonates Targeting Ion Channels and Musculoskeletal Effects

Bisphosphonates (BPs) are the most used bone-specific anti-resorptive agents, often chosen as first-line therapy in several bone diseases characterized by an imbalance between osteoblast-mediated bone production and osteoclast-mediated bone resorption. BPs target the farnesyl pyrophosphate synthase (FPPS) in osteoclasts, reducing bone resorption. Lately, there has been an increasing interest in BPs direct pro-survival/pro-mineralizing properties in osteoblasts and their pain-relieving effects. Even so, molecular targets involved in these effects appear now largely elusive. Ion channels are emerging players in bone homeostasis. Nevertheless, the effects of BPs on these proteins have been poorly described. Here we reviewed the actions of BPs on ion channels in musculoskeletal cells. In particular, the TRPV1 channel is essential for osteoblastogenesis. Since it is involved in bone pain sensation, TRPV1 is a possible alternative target of BPs. Ion channels are emerging targets and anti-target for bisphosphonates. Zoledronic acid can be the first selective musculoskeletal and vascular KATP channel blocker targeting with high affinity the inward rectifier channels Kir6.1-SUR2B and Kir6.2-SUR2A. The action of this drug against the overactive mutants of KCNJ9-ABCC9 genes observed in the Cantu’ Syndrome (CS) may improve the appropriate prescription in those CS patients affected by musculoskeletal disorders such as bone fracture and bone frailty.

Non-Invasive Physical Plasma Treatment after Tooth Extraction in a Patient on Antiresorptive Medication Promotes Tissue Regeneration

Postoperative tissue regeneration can be negatively affected by bisphosphonate administration, especially in patients with oncologic diseases. A serious complication of bisphosphonate therapy is the medication-related osteonecrosis of the jaw (MRONJ), which can be observed mainly after dental surgery. MRONJ is a progressive destruction of the bone that requires patients to stay in hospital for extended periods of time. For this reason, primary wound closure is particularly important in surgical procedures. In the case of wound dehiscence, there is a very high risk for MRONJ. In recent years, non-invasive physical plasma (NIPP) has become known for improving wound healing on the one hand, but also for its promising efficacy in cancer therapy on the other hand. We report on a 63-year-old patient with a history of multiple myeloma and receiving zoledronate, who developed wound dehiscence after tooth extraction. NIPP treatment resulted in complete epithelialization of the entire wound dehiscence. In conclusion, the use of NIPP in patients receiving antiresorptive drugs seems to support tissue regeneration and thus could be an important tool for the prevention of MRONJ.

Aromatic Bis[aminomethylidenebis(phosphonic)] Acids Prevent Ovariectomy-Induced Bone Loss and Suppress Osteoclastogenesis in Mice

Osteoporosis is a skeletal disease associated with excessive bone turnover. Among the compounds with antiresorptive activity, nitrogen-containing bisphosphonates play the most important role in antiosteoporotic treatment. In previous studies, we obtained two aminomethylidenebisphosphonates—benzene-1,4-bis[aminomethylidene(bisphosphonic)] (WG12399C) acid and naphthalene-1,5-bis[aminomethylidene(bisphosphonic)] (WG12592A) acid—which showed a significant antiproliferative activity toward J774E macrophages, a model of osteoclast precursors. The aim of these studies was to evaluate the antiresorptive activity of these aminobisphosphonates in ovariectomized (OVX) Balb/c mice. The influence of WG12399C and WG12592A administration on bone microstructure and bone strength was studied. Intravenous injections of WG12399C and WG12592A bisphosphonates remarkably prevented OVX-induced bone loss; for example, they sustained bone mineral density at control levels and restored other bone parameters such as trabecular separation. This was accompanied by a remarkable reduction in the number of TRAP-positive cells in bone tissue. However, a significant improvement in the quality of bone structure did not correlate with a parallel increase in bone strength. In ex vivo studies, WG12399C and WG12592A remarkably bisphosphonates reduced osteoclastogenesis and partially inhibited the resorptive activity of mature osteoclasts. Our results show interesting biological activity of two aminobisphosphonates, which may be of interest in the context of antiresorptive therapy.

Interplay between mineral crystallinity and mineral accumulation in health and postmenopausal osteoporosis

Osteoporosis is characterized by an imbalance between bone formation and resorption rates, resulting in bone loss. For ethical reasons, effects of antiosteoporosis drugs are compared against patients receiving vitamin D and calcium supplementation which is a mild antiresorptive regimen. Bone formation may be resolved into two phases: the initial formation of mineral crystals (primary nucleation) and the subsequent mineral accumulation (secondary nucleation and mineral growth) on them. In this study, we used Raman microspectroscopic analysis of iliac crest biopsies from healthy females (N = 108), postmenopausal osteoporosis patients receiving vitamin D and calcium supplementation (PMOP-S; N = 66), and treatment-naïve postmenopausal osteoporosis patients (PMOP-TN; N = 12) to test the hypothesis that at forming trabecular surfaces, mineral maturity / crystallinity of the youngest crystallites associates with the amount of subsequent mineral accumulation. The surfaces of analysis were chosen based on the presence of fluorescent double labels, defining three distinct tissue ages. The results indicated that when adjusted for age and tissue age, there were no differences in amount of mineral formed between healthy females and either PMOP-S or PMOP-TN, while both PMOP-S and PMOP-TN had larger crystallites compared to healthy females. Moreover, significant differences existed between PMOP-S and PMOP-TN in size of initial crystals formed as well as rate of mineral accumulation and maturation. These findings suggest an additional mechanism that may contribute to the decreased mineral content evident in PMOP, and provide a potential target for the development of new interventions. STATEMENT OF SIGNIFICANCE: We used Raman microspectroscopic analysis of iliac crest biopsies from healthy females and postmenopausal osteoporosis patients (PMOP) receiving placebo to test the hypothesis that at forming trabecular surfaces, mineral maturity / crystallinity (MMC) of the youngest crystallites associates with the amount of subsequent mineral accumulation. This can affect bone mechanical properties as larger crystallites have been shown to result in compromised mechanical attributes; and larger crystallites grow slower compared to smaller ones. The results of the present analysis indicate that increased MMC of the youngest formed mineral may contribute to the bone mineral loss evident in PMOP and the accompanying increased fracture risk independently of bone turnover rate.

Bisphosphonates impair the onset of bone formation at remodeling sites

Bisphosphonates are widely used anti-osteoporotic drugs targeting osteoclasts. They strongly inhibit bone resorption, but also strongly reduce bone formation. This reduced formation is commonly ascribed to the mechanism maintaining the resorption/formation balance during remodeling. The present study provides evidence for an additional mechanism where bisphosphonates actually impair the onset of bone formation after resorption. The evidence is based on morphometric parameters recently developed to assess the activities reversing resorption to formation. Herein, we compare these parameters in cancellous bone of alendronate- and placebo-treated postmenopausal osteoporotic patients. Alendronate increases the prevalence of eroded surfaces characterized by reversal cells/osteoprogenitors at low cell density and remote from active bone surfaces. This indicates deficient cell expansion on eroded surfaces - an event that is indispensable to start formation. Furthermore, alendronate decreases the coverage of these eroded surfaces by remodeling compartment canopies, a putative source of reversal cells/osteoprogenitors. Finally, alendronate strongly decreases the activation frequency of bone formation, and decreases more the formative compared to the eroded surfaces. All these parameters correlate with each other. These observations lead to a model where bisphosphonates hamper the osteoprogenitor recruitment required to initiate bone formation. This effect results in a larger eroded surface, thereby explaining the well-known paradox that bisphosphonates strongly inhibit bone resorption without strongly decreasing eroded surfaces. The possible mechanism for hampered osteoprogenitor recruitment is discussed: bisphosphonates may decrease the release of osteogenic factors by the osteoclasts, and/or bisphosphonates released by osteoclasts may act directly on neighboring osteoprogenitor cells as reported in preclinical studies.

A single dose of zoledronate preserves bone mineral density for up to 2 years after a second course of romosozumab

This phase 2 study evaluated the efficacy and safety of transitioning to zoledronate following romosozumab treatment in postmenopausal women with low bone mass. A single dose of 5 mg zoledronate generally maintained the robust BMD gains accrued with romosozumab treatment and was well tolerated.

INTRODUCTION

Follow-on therapy with an antiresorptive agent is necessary to maintain the skeletal benefits of romosozumab therapy. We evaluated the use of zoledronate following romosozumab treatment.

METHODS

This phase 2, dose-finding study enrolled postmenopausal women with low bone mineral density (BMD). Subjects who received various romosozumab doses or placebo from months 0-24 were rerandomized to denosumab (60 mg SC Q6M) or placebo for 12 months, followed by open-label romosozumab (210 mg QM) for 12 months. At month 48, subjects who had received active treatment for 48 months were assigned to no further active treatment and all other subjects were assigned to zoledronate 5 mg IV. Efficacy (BMD, P1NP, and β-CTX) and safety were evaluated for 24 months, up to month 72.

RESULTS

A total of 141 subjects entered the month 48-72 period, with 51 in the no further active treatment group and 90 in the zoledronate group. In subjects receiving no further active treatment, lumbar spine (LS) BMD decreased by 10.8% from months 48-72 but remained 4.2% above the original baseline. In subjects receiving zoledronate, LS BMD was maintained (percentage changes: - 0.8% from months 48-72; 12.8% from months 0-72). Similar patterns were observed for proximal femur BMD in both groups. With no further active treatment, P1NP and β-CTX decreased but remained above baseline at month 72. Following zoledronate, P1NP and β-CTX levels initially decreased but approached baseline by month 72. No new safety signals were observed.

CONCLUSION

A zoledronate follow-on regimen can maintain robust BMD gains achieved with romosozumab treatment.

Zoledronate

Zoledronate is the most potent and most long-acting bisphosphonate in clinical use, and is administered as an intravenous infusion. Its major uses are in osteoporosis, Paget's disease, and in myeloma and cancers to reduce adverse skeletal related events (SREs). In benign disease, it is a first- or second-line treatment for osteoporosis, achieving anti-fracture efficacy comparable to that of the RANKL blocker, denosumab, over 3 years, and it reduces fracture risk in osteopenic older women. It is the preferred treatment for Paget's disease, achieving higher rates of remissions which are much more prolonged than with any other agent. Some trials have suggested that it reduces mortality, cardiovascular disease and cancer, but these findings are not consistent across all studies. It is nephrotoxic, so should not be given to those with significant renal impairment, and, like other potent anti-resorptive agents, can cause hypocalcemia in patients with severe vitamin D deficiency, which should be corrected before administration. Its most common adverse effect is the acute phase response, seen in 30-40% of patients after their first dose, and much less commonly subsequently. Clinical trials in osteoporosis have not demonstrated increases in osteonecrosis of the jaw or in atypical femoral fractures. Observational databases are currently inadequate to determine whether these problems are increased in zoledronate users. Now available as a generic, zoledronate is a cost-effective agent for fracture prevention and for management of Paget's disease, but wider provision of infusion facilities is important to increase patient access. There is a need to further explore its potential for reducing cancer, cardiovascular disease and mortality, since these effects could be substantially more important than its skeletal actions.

Early changes in bone turnover predict longer-term changes in bone mineral density but not trabecular bone score in frail older women

Clinicians and patients want to know if therapy is working early in their course of treatment. We found that early changes in bone turnover markers at 6 months were associated with long-term changes in bone mineral density but not trabecular bone score at 12 and 24 months.

PURPOSE

We sought to examine the association between shorter-term changes in markers of bone turnover and longer-term changes in bone mineral density (BMD) and microstructure in a cohort of frail elderly women with multiple comorbid conditions including osteoporosis.

METHODS

We performed a secondary analysis of a 2-year zoledronic acid trial for osteoporosis in 155 women residents of long-term care communities (mean age 86.9 years). We examined the association of the 6-month change in serum C-terminal crosslinking telopeptide of type I collagen (CTX) and serum intact procollagen type I N propeptide (PINP) with the 12- and 24-month changes in BMD at the spine and hip and the trabecular bone score (TBS), an indirect measure of bone microstructure.

RESULTS

For every 0.2-ng/ml 6-month CTX decrease, the corresponding increase in spine BMD at 12 and 24 months was 0.2% (p = 0.7210) and 1.1% (p = 0.0396), respectively; total hip BMD 1.1% (p = 0.0279) and 0.9% (p = 0.0716); and femoral neck BMD 1.7% (p = 0.0079) and 0.9% (p = 0.1698). Similarly, for every 20-ng/ml 6-month PINP decrease, the corresponding increase in spine BMD at 12 and 24 months was 0.9% (p = 0.0286) and 1.4% (p = 0.0012), respectively; total hip BMD 1.4% (p = 0.0005) and 1.4% (p = 0.0006); and femoral neck BMD 2.3% (p < 0.0001) and 2.0% (p < 0.0001). Bone marker changes were not consistently associated with TBS changes.

CONCLUSION

Shorter-term 6-month changes in bone turnover markers are associated with the long-term changes in BMD over 1-2 years in the spine and hip but not with TBS.

Synergistic effect of graphene oxide and zoledronic acid for osteoporosis and cancer treatment

Zoledronic acid (ZOL) is a third generation bisphosphonate which can be used as a drug for the treatment of osteoporosis and metastasis. In this study, graphene oxide (GO) is conjugated with ZOL, and the nanostructured material is evaluated in terms viability, proliferation and differentiation. Furthermore, the associated morphological changes of bone marrow-derived mesenchymal stem cells (BM-MSC), and Michigan Cancer Foundation-7 (MCF-7) breast cancer cells, as well as the effect of the drugs on mineralization of BM-MSCs are investigated using a variety of characterization techniques including Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM) as well as alamar blue, acridine orange, and alizarin red assays. Nanostructured ZOL-GO with an optimum performance is synthesized using ZOL and GO suspensions with the concentration of 50 µM and 2.91 ng/ml, respectively. ZOL-GO nanostructures can facilitate the mineralization of BM-MSC cells, demonstrated by the formation of clusters around the cells. The results obtained confirm the performance of ZOL-GO nanostructures as promising drug complexes for the treatment of osteoporosis and metastasis.

Zoledronic acid for the treatment of pregnancy-associated femoral head necrosis: A case report

Introduction

The management of pregnancy-associated femoral necrosis is controversial. Conservative management may eventually lead to hip replacement.

Case

A 40-year-old woman developed necrosis of the left hip during her first pregnancy. Treatment with zoledronic acid three months after delivery resulted in rapid reduction of the necrotic area. The patient's second pregnancy shortly afterwards had no complications. A magnetic resonance scan three years later documented complete resolution.

Conclusion

Femoral head necrosis should be suspected in the differential diagnosis of pain in pregnancy. Zoledronic acid given in the early stages prevented progression to hip arthritis in this case.

•

Osteonecrosis of the femoral head must always be taken into account in the differential diagnosis of hip pain in pregnancy.

•

Conservative treatment of pregnancy-associated osteonecrosis may lead to hip replacement.

•

A prompt treatment may be essential to prevent arthroplasty.

•

We report for the first time a case of femoral osteonecrosis treated with zoledronate in a primigravid woman.

•

Zoledronic acid proved safe and effective and the outcome persisted throughout the duration of a second pregnancy.

Osteoporosis Therapeutics 2020

Numerous safe and efficient drug therapies are currently available to decrease risk of low trauma fractures in patients with osteoporosis including postmenopausal, male, and secondary osteoporosis. In this chapter, we give first an overview of the most important outcomes regarding fracture risk reduction, change in bone mineral density (BMD by DXA) and/or bone markers of the phase III clinical studies of well-established therapies (such as Bisphosphonates, Denosumab or Teriparatide) and also novel therapies (such as Romosozumab or Abaloparatide) and highlight their mechanisms of action at bone tissue/material level. The latter understanding is not only essential for the choice of drug, duration and discontinuation of treatment but also for the interpretation of the clinical outcomes (in particular of eventual changes in BMD) after drug administration. In the second part of this chapter, we focus on the management of different forms of osteoporosis and give a review of the respective current guidelines for treatment. Adverse effects of treatment such as atypical femoral fractures, osteonecrosis of the jaw or influence of fracture healing are considered also in this context.

Update on Menopausal Hormone Therapy for Fracture Prevention

PURPOSE OF REVIEW

The goal of the review is to assess the appropriateness of menopausal hormone therapy (MHT) for the primary prevention of bone loss in women at elevated risk in the early years after menopause.

RECENT FINDINGS

Estrogen alone or combined with progestin to protect the uterus from cancer significantly reduces the risk of osteoporosis-related fractures. MHT increases type 1 collagen production and osteoblast survival and maintains the equilibrium between bone resorption and bone formation by modulating osteoblast/osteocyte and T cell regulation of osteoclasts. Estrogens have positive effects on muscle and cartilage. Estrogen, but not antiresorptive therapies, can attenuate the inflammatory bone-microenvironment associated with estrogen deficiency. However, already on second year of administration, MHT is associated with excess breast cancer risk, increasing steadily with duration of use. MHT should be considered in women with premature estrogen deficiency and increased risk of bone loss and osteoporotic fractures. However, MHT use for the prevention of bone loss is hindered by increase in breast cancer risk even in women younger than 60 years old or who are within 10 years of menopause onset.

Nitrogen Containing Bisphosphonates Impair the Release of Bone Homeostasis Mediators and Matrix Production by Human Primary Pre-Osteoblasts

Bisphosphonates (BPs) represent the first-line treatment for a wide array of bone disorders. Despite their well-known action on osteoclasts, the effects they induce on osteoblasts are still unclear. In order to shed light on this aspect we evaluated the impact of two nitrogen containing bisphosphonates, Alendronate (ALN) and Zoledronate (ZOL), on human primary pre-osteoblasts. At first, we showed an inhibitory effect on cell viability and alkaline phosphatase activity starting from µM concentrations of both drugs. In addition, an inhibitory trend on mineralized nodules deposition was observed. Then low doses of both ALN and ZOL rapidly increased the release of the pro-inflammatory mediators TNFα and IL-1β, while increased DKK-1 and Sclerostin, both inhibitors of osteoblastogenesis. Finally, ALN and 10^-7M ZOL decreased the expression of type I Collagen and Osteopontin, while both drugs slightly stimulated SPARC production. With these results, we would like to suggest a direct inhibitory action on bone-forming cells by nitrogen containing bisphosphonates.

Updates in CKD-Associated Osteoporosis

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is associated with bone loss and fractures. The purpose of this review is to provide clinicians with an overview of the underlying pathogenesis of CKD-associated osteoporosis, and a summary of the current diagnostic and therapeutic approaches to this disease.

RECENT FINDINGS

In 2017, the Kidney Disease Improving Global Outcomes Committee on Bone Quality updated their guidelines to include screening for osteoporosis and fracture risk by dual energy X-ray absorptiometry in patients with CKD. Once a diagnosis of osteoporosis and/or fracture risk is established, it is not clear how nephrologists should manage their patients. Patients with CKD should be screened for CKD-associated osteoporosis and considered for strategies that prevent bone loss and fractures. Assessment of bone turnover via imaging, biochemical testing, or bone biopsy can help guide the choice of therapy. Randomized controlled trials are needed to assess safety and efficacy of treatments to prevent bone loss and fractures.

Does zoledronate therapy make mandibular bone susceptible to fracture? A radiographical and biomechanical study in rats

INTRODUCTION

The aim of this study was to evaluate the effect of zoledronate therapy on susceptibility of mandibular bone to fracture in rats.

METHODS

Fifty rats were randomly allocated to two groups of 25 animals. The rats in group Z received monthly intravenous infusion of 0.06 mg/kg zoledronate for 6 months. The rats in the group C were injected with an equal volume of saline in the same manner. A month after the last zoledronate/saline administration, all 50 rats were euthanized. Using a cone beam computed tomography, the cortical thickness of inferior border of mandible and the mandibular bone mineral density were calculated, and using a three-point bending test, the peak load failure and the ultimate stress of mandibular bone were determined.

RESULTS

The mean mandibular inferior cortical bone thickness and the mean bone mineral density were significantly larger in zoledronate-treated rats (0.30 ± 0.02 mm and 1045.00 ± 185.79, respectively) compared to control rats (0.21 ± 0.01 mm and 878.66 ± 166.53, respectively). The peak load and the ultimate stress were lower in the zoledronate-treated hemimandibles (84.61 ± 33.62 N and 1.76 ± 0.72 MPa, respectively) compared to the control hemimandibles (98.36 ± 16.5 9 N and 2.03 ± 0.44 MPa, respectively).

CONCLUSION

Zoledronate therapy reduced the mechanical strength of the mandibles, implying an increased risk of mandibular fracture in rats.

Immediate implant placement following 1-year treatment with oral versus intravenous bisphosphonates: a histomorphometric canine study on peri-implant bone

OBJECTIVES

Bisphosphonates (BPs) are anti-resorptive medications with inhibitory effects on osteoclasts which decrease bone turnover. The present study aimed to assess the early effects of BPs on peri-implant bone.

MATERIALS AND METHODS

Twelve female mongrel dogs were assigned to one control and two experimental groups as follows: 12 months of oral alendronate (ALN, 3.5 mg/kg/week) or intravenous (IV) pamidronate (PAM, 1 mg/kg/week) for experimental groups. Following 8 weeks after implant insertion, the specimens were sacrificed, histological evaluation was performed, and C-terminal telopeptide of collagen I (CTx) analysis was performed on serums.

RESULTS

PAM demonstrated the greatest marginal bone level (MBL), 2.64 ± 0.48, followed by ALN and control, 2.5 ± 0.4 and 0.66 ± 0.5 respectively. The least bone-implant contact was observed in PAM group (%39 ± 0.03) while it was significantly greater in the control group (p < 0.05). PAM and ALN demonstrated < 10 CTx levels versus > 300 in controls.

CONCLUSION

It is assumed that long-term oral or IV BP therapy decreases marginal bone resorption and osseointegration. These changes were more accentuated in IV BP administration. CTx does not seem to be a precise predictor for bisphosphonate-related osteonecrosis of the jaw.

CLINICAL RELEVANCE

BPs impair peri-implant bone remodeling and this phenomena may be effective for reducing resorption at esthetic zone implants; however, decrease in osseointegration may be a concern for implant treatment in patients receiving BPs.

The MEK5/ERK5 mitogen-activated protein kinase cascade is an effector pathway of bone-sustaining bisphosphonates that regulates osteogenic differentiation and mineralization

Bisphosphonates play an important role in the treatment of metabolic bone diseases such as osteoporosis. In addition to their anti-resorptive activity by triggering osteoclast apoptosis, nitrogen-containing bisphosphonates (N-BP) may also influence osteogenic differentiation, which might rely on their capacity to inhibit the mevalonate pathway. In vascular endothelial cells inhibition of this pathway by cholesterol-lowering statins activates the MEK5/ERK5 mitogen-activated protein kinase cascade, which plays an important role in cellular differentiation, apoptosis or inflammatory processes. Here we evaluated whether N-BP may also target the MEK5/ERK5 pathway and analysed the consequences of ERK5 activation on osteogenic differentiation. We show that N-BP dose-dependently activate ERK5 in primary human endothelial cells and osteoblasts. The mechanism likely involves farnesyl pyrophosphate synthase inhibition and subsequent functional inhibition of the small GTPase Cdc42 since siRNA-mediated knockdown of both genes could reproduce N-BP-induced ERK5 activation. ERK5 activation resulted in regulation of several bone-relevant genes and was required for calcification and osteogenic differentiation of bone marrow-derived mesenchymal stems cells as evident by the lack of alkaline phosphatase induction and alizarin-red S staining observed upon ERK5 knockdown or upon differentiation initiation in presence of a pharmacological ERK5 inhibitor. Our data provide evidence that N-BP activate the MEK5/ERK5 cascade and reveal an essential role of ERK5 in osteogenic differentiation and mineralization of skeletal precursors.

Bisphosphonates hinder osteoblastic/osteoclastic differentiation in the maxillary sinus mucosa-derived stem cells

OBJECTIVES

Although bisphosphonates (BPs) are known to be associated with osteonecrosis of the maxilla, the precise effects of BPs on bone metabolism in human maxillary sinus mucosal cells (HMSMCs) are not yet known. The purposes of this study were to examine the effects of the BPs zoledronate (ZOL) and alendronate (ALN) on osteoblastic and osteoclastic differentiation in HMSMCs and to investigate the signaling pathways involved.

MATERIALS AND METHODS

The effects of ZOL and ALN were assessed for osteoblast differentiation by alkaline phosphatase (ALP) activity, alizarin red staining, and RT-PCR for genes encoding Runx2 and osterix. Receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclast differentiation in bone marrow macrophages (BMMs) was also examined.

RESULTS

ZOL and ALN both suppressed osteoblastic differentiation, as evidenced by their effects on ALP activity, mineralization nodule formation, and the mRNA expression levels of osteoblastic transcript factors. The RANKL/osteoprotegerin ratio in HMSMCs was increased by ALN, whereas ZOL had the opposite effect. Conditioned medium obtained from ALN-treated HMSMCs stimulated osteoclast formation and upregulated NFATc1 expression, whereas conditioned medium from ZOL-treated cells did not. ALN was more cytotoxic and stimulated apoptosis more strongly than ZOL. BPs decreased the protein levels of the non-canonical Wnt signaling protein Wnt5a and calmodulin-dependent kinase II. Moreover, recombinant human Wnt5a reversed the effects of BPs on osteoblastic and osteoclastic differentiation.

CONCLUSION

This study is the first demonstration that BPs exert negative effects on osteoblastic and osteoclastic processes via the non-canonical Wnt pathway in HMSMSCs.

CLINICAL RELEVANCE

It suggests that patients taking BPs during the period of maxillary sinus lifting and amentation should be given special attention.

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.

Osseous changes in patients with medication-related osteonecrosis of the jaws

OBJECTIVES

Medication-related osteonecrosis of the jaw (MRONJ) is a severe side effect of antiresorptive agents. The aim of this study was to investigate the osseous changes in patients with MRONJ.

METHODS

Cone beam CT (CBCT) images of 25 patients with MRONJ and controls were retrospectively evaluated. Buccal, lingual, apical cortical bone thicknesses; buccal, lingual, apical intracortical and cancellous bone density; diameter of mental foramen and incisive canal, and width of mental foramen were measured.

RESULTS

Buccal and apical cortical bone thicknesses were increased; however intracortical radiodensity values decreased in the Study Group when compared with the Control Group (p = 0.007, p = 0.001). Narrowing of incisive canal was observed in patients with MRONJ (p = 0.000).

CONCLUSIONS

Clinician should have awareness about narrowing of incisive canal, apical and buccal cortical bone thickening, decreasing in cancellous bone radiodensity, and the lingual cortex destruction in patients with MRONJ.

Preclinical Models for Skeletal Research: How Commonly Used Species Mimic (or Don’t) Aspects of Human Bone

Preclinical studies play an indispensable role in exploring the biological regulation of the musculoskeletal system. They are required in all drug development pipelines where both small and large animal models are needed to understand efficacy and side effects. This brief review highlights 4 aspects of human bone, longitudinal bone growth, intracortical remodeling, collagen/mineral interface, and age-related changes, and discusses how various animal models recapitulate (or don’t) these aspects of human skeletal physiology.

Zoledronic acid improves bone histomorphometry in a murine model of Rett syndrome

Rett syndrome (RTT) is a neurodevelopmental disorder predominately affecting young females, caused by deficiency of the global transcriptional protein methyl CpG binding protein 2 (MeCP2). Osteoblasts express MeCP2 and girls with RTT experience early onset osteoporosis, decreased bone mass and an increased fracture risk. There is no defined treatment for osteoporosis associated with RTT. The present study evaluated the effects of zoledronic acid (ZA), a third generation nitrogen-containing bisphosphonate with primarily anti-osteoclastic activity, in a mouse model of MeCP2 deficiency. Mice received weekly injections of 20μg/kg ZA for six weeks. Due to the shortened lifespan of hemizygous male (Mecp2-null) mice, treatment began at 3weeks of age for this group and corresponding wildtype (WT) male mice. Treatment for heterozygous (HET) and WT female mice began at 8weeks of age. Micro-computed tomography (micro-CT) and dynamic analyses of bone turnover were performed. ZA treatment led to significant increases in bone volume fraction, number, connectivity density and apparent density of trabecular bone in all genotypes of mice. In contrast, cortical bone generally was unaffected by ZA injections. Parameters of bone turnover, including mineral apposition rate, labeled bone surface and bone formation rate decreased after treatment with ZA. Mecp2-null mice had reduced labeled bone surface and bone formation rate compared to WT male mice. The results indicate that ZA treatment significantly improved trabecular bone mass in a murine model of RTT with little effect on cortical bone.

Effects of abaloparatide-SC (BA058) on bone histology and histomorphometry: The ACTIVE phase 3 trial

There are a number of effective treatments for osteoporosis but most are in the antiresorptive class of compounds. Abaloparatide-SC is a new osteoanabolic agent, which increased bone mineral density and lowered the risk of osteoporosis-related fractures in the phase 3 ACTIVE trial. The objective of this report is to describe the effects of abaloparatide-SC 80μg on bone histology and histomorphometry in iliac crest bone biopsies from this trial in which participants were randomized to receive blinded daily subcutaneous injections of placebo or abaloparatide-SC 80μg/d or open-label teriparatide 20μg/d for 18months. Iliac crest bone biopsies were obtained between 12 and 18months. Qualitative histological analysis of biopsies from abaloparatide-SC-treated patients revealed normal bone microarchitecture without evidence of adverse effects on mineralization or on the formation of normal lamellar bone. There were no bone marrow abnormalities, marrow fibrosis nor was there presence of excess osteoid or woven bone. There were few significant differences among the three treatment groups in a standard panel of static and dynamic histomorphometric indices. The mineral apposition rate was higher in the teriparatide-treated group than in the placebo-treated group. The eroded surface was lower in the abaloparatide-SC-treated group than in the placebo-treated group. Cortical porosity was higher in both the abaloparatide-SC- and the teriparatide-treated groups than in the placebo-treated group. We conclude that histological and histomorphometric analysis of iliac crest bone biopsies from subjects who were treated for up to 18months with abaloparatide-SC showed no evidence of concern for bone safety.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT01343004.

Reactive oxygen species are required for zoledronic acid-induced apoptosis in osteoclast precursors and mature osteoclast-like cells

Inhibiting osteoclasts and osteoclast precursors to reduce bone resorption is an important strategy to treat osteoclast-related diseases, such as osteoporosis, inflammatory bone loss, and malignant bone metastasis. However, the mechanism by which apoptosis is induced in the osteoclasts and their precursors are not completely understood. Here, we used nitrogen-containing bisphosphonate zoledronic acid (ZA) to induce cell apoptosis in human and murine osteoclast precursors and mature osteoclast-like cells. Caspase-3-mediated cell apoptosis occurred following the ZA (100 μM) treatment. Reactive oxygen species (ROS) were also generated in a time-dependent manner. Following knock-down of the p47^phox expression, which is required for ROS activation, or co-treatment with the ROS inhibitor, N-acetyl-L-cysteine, ZA-induced apoptosis was significantly suppressed in both osteoclast precursors and mature osteoclast-like cells. The ROS-activated mitogen-activated protein kinases pathways did not trigger cell apoptosis. However, a ROS-regulated Mcl-1 decrease simultaneously with glycogen synthase kinase (GSK)-3β promoted cell apoptosis. These findings show that ZA induces apoptosis in osteoclast precursors and mature osteoclast-like cells by triggering ROS- and GSK-3β-mediated Mcl-1 down-regulation.

Vitamin D and calcium supplementation for three years in postmenopausal osteoporosis significantly alters bone mineral and organic matrix quality

Prospective, controlled clinical trials in postmenopausal osteoporosis typically compare effects of an active drug with placebo in addition to vitamin D and calcium supplementation in both treatment arms. While clinical benefits are documented, the effect of this supplementation in the placebo arm and in clinical practice on bone material composition properties is unknown. The purpose of the present study was to evaluate these bone quality indices (specifically mineral/matrix, nanoporosity, glycosaminoglycan content, mineral maturity/crystallinity, and pyridinoline content) in patients that either received long-term vitamin D (400-1200IU) and calcium (1.0-1.5g) supplementation, or did not. We have analyzed by Raman microspectroscopy the bone forming trabecular surfaces of iliac crest in pre-treatment samples of a teriparatide study and the endpoint biopsies of the control arm obtained from the HORIZON trial. In general, the mineral/matrix ratio and the glycosaminoglycan (GAG) content was higher while nanoporosity, (a surrogate for tissue water content), the mineral maturity/crystallinity (MMC) and the pyridinoline (Pyd) content was lower in patients without long-term supplementation. Moreover, all indices were significantly dependent on tissue age. In conclusion, vitamin D and calcium supplementation is associated with altered mineral and organic matrix properties.

Zoledronic acid in vivo increases in vitro proliferation of rat mesenchymal stromal cells

Background and purpose - Bisphosphonates are widely used in the treatment of bone loss, but they might also have positive effects on osteoblastic cells and bone formation. We evaluated the effect of in vivo zoledronic acid (ZA) treatment and possible concomitant effects of ZA and fracture on the ex vivo osteogenic capacity of rat mesenchymal stromal cells (MSCs). Methods - A closed femoral fracture model was used in adult female rats and ZA was administered as a single bolus or as weekly doses up to 8 weeks. Bone marrow MSCs were isolated and cultured for in vitro analyses. Fracture healing was evaluated by radiography, micro-computed tomography (μCT), and histology. Results - Both bolus and weekly ZA increased fracture-site bone mineral content and volume. MSCs from weekly ZA-treated animals showed increased ex vivo proliferative capacity, while no substantial effect on osteoblastic differentiation was observed. Fracture itself did not have any substantial effect on cell proliferation or differentiation at 8 weeks. Serum biochemical markers showed higher levels of bone formation in animals with fracture than in intact animals, while no difference in bone resorption was observed. Interestingly, ex vivo osteoblastic differentiation of MSCs was found to correlate with in vivo serum bone markers. Interpretation - Our data show that in vivo zoledronic acid treatment can influence ex vivo proliferation of MSCs, indicating that bisphosphonates can have sustainable effects on cells of the osteoblastic lineage. Further research is needed to investigate the mechanisms.

Atypical femoral fractures and current management

With the rapid increase in patients receiving bisphosphonates (BPs) for treating osteoporosis, one of the clinical complications associated with its long-term use is atypical femoral fractures (AFFs). Although the absolute risk for AFFs is low and it was a consensus that AFFs were acceptable compared with the amount of osteoporotic fractures BPs have prevented, epidemiological studies have proved that BPs had a strong association with AFFs and possibly more people were going to suffer from this adverse effect with wide prescriptions of this drug. In addition, AFFs seemed to have impaired ability to heal. Thus, to understand the mechanism(s) behind AFFs is important and desirable for considering preventive measures. This article reviewed the clinical features of AFFs as well as potential underlining pathological characteristics, such as the decreased turnover rate caused by BPs that led to multiple-level alternations, e.g., changes not only at cellular and tissue levels, but also related to changes in bone micro- and macrostructure and organic/inorganic contents, leading to potentially compromised mechanical properties of cortical bone when exposed to prolonged BP therapy. Severely suppressed bone turnover may also be the underlying mechanism for impaired fracture healing in patients with AFFs. The rising concerns about the risk for AFFs in nonosteoporotic patients receiving high-dose BPs to treat cancers were also discussed. Detailed investigation will help develop potential targeted pharmacological treatments such as parathyroid hormone. In addition, potential innovative internal fixation implants were discussed with regard to dynamic and biological fixation for enhancing AFF repair.

Computed tomographic assessment of early changes of the mandible in bisphosphonate-treated patients

OBJECTIVES

To compare the computed tomography (CT) features of mandibular cancellous and cortical bones between patients with bisphosphonate (BP) administration and those without and to assess the early changes of the mandible in BP-treated patients.

STUDY DESIGN

Twenty-four BP-treated patients suffering from medication-related osteonecrosis of the jaw (MRONJ) were enrolled in this study. For comparison, 20 patients suffering from osteomyelitis and 20 patients without pathology in the jaw were also enrolled, all of whom did not receive BP treatment. The CT values of the cancellous and cortical bone and the cortical bone widths were measured.

RESULTS

In the MRONJ and osteomyelitis groups, there were significant differences in the CT values of cancellous and cortical bones between the affected and unaffected areas. In patients with stage 0 MRONJ, a significant difference was noted in the cancellous bone CT values between these areas. The cancellous bone CT values at the affected and unaffected areas in the BP-treated group were significantly higher than in the control groups. In patients with stage 0 MRONJ, the cancellous bone CT values at the affected area were also significantly higher than in the healthy patients. The cortical bone widths in the unaffected areas in the BP-treated patients were significantly larger than in healthy patients.

CONCLUSIONS

The cancellous bone CT values were higher in the BP-treated group, including in patients with stage 0 MRONJ, and CT may provide useful quantitative information.

Effects of zoledronic acid on bone fusion in osteoporotic patients after lumbar fusion

Treatment with zoledronic acid in osteoporotic patients with spinal fusion shortens the duration of time to fusion, improves the fusion rate, prevents the subsequent adjacent vertebral compression fractures, improves the clinical outcomes, and prevents immobilization-induced bone loss in the hip.

INTRODUCTION

The objective of the study was to explore the effects of zoledronic acid on the healing process in osteoporotic patients following spinal fusion in a randomized, placebo-controlled, and triple-blinded study.

METHODS

Seventy-nine osteoporotic patients with single-level degenerative spondylolisthesis were randomly assigned to receive either zoledronic acid infusion (zoledronic acid group) or saline infusion (controls) after spinal fusion. Functional radiography and CT scans were used to evaluate fusion status. Bone formation was graded into three categories: Grade A (bridging bone bonding with adjacent vertebral bodies), Grade B (bridging bone bonding with either superior or inferior vertebral body), or Grade C (incomplete bony bridging). A solid fusion was defined as less than 5° of angular motion with Grade A or B bone formation. Adjacent vertebral compression fractures (VCF) were assessed on MRI at 12 months after surgery. Serum level of carboxy terminal cross-linked telopeptide of type I collagen (β-CTX) and amino-terminal propeptide of type I procollagen (PINP) was measured. Bone mineral density (BMD) was measured by DXA. Oswestry Disability Index (ODI) was used to assess the clinical outcomes.

RESULTS

Grade A or B bridging bone was more frequently observed in zoledronic acid group at 3, 6, and 9 months post-operation compared to the control group (p < 0.05). At 12 -months post-operation, bridging bone and solid fusion were not significantly different between groups. No patients in zoledronic acid group showed aVCF, whereas six patients (17 %) in the control group did (p < 0.05). Both β-CTX and PINP were suppressed in zoledronic acid group. BMD at the femoral neck decreased rapidly and did not return to the preoperative level in the controls at 3 (-1.4 %), 6 (-2.5 %), and 12 (-0.8 %) months after surgery. Zoledronic acid prevented this immobilization-induced bone loss and increased BMD. ODI showed the improved clinical outcomes compared with controls at 9 and 12 months post-surgery.

CONCLUSION

Treatment with zoledronic acid in osteoporotic patients with spinal fusion shortens the time to fusion, improves the fusion rate, prevents subsequent aVCFs, and improves clinical outcomes.

Dose-dependent inhibitory effects of zoledronic acid on osteoblast viability and function in vitro

Zoledronic acid (ZA), which is one of the most potent and efficacious bisphosphonates, has been commonly used in clinical practice for the treatment of various bone disorders. The extensive use of ZA has been associated with increasing occurrence of jaw complications, now known as bisphosphonate-associated osteonecrosis of the jaw (BRONJ). However, the mechanism underlying BRONJ remains to be fully elucidated. The aim of the present study was to investigate the effects of different concentrations of ZA on the MC3T3-E1 murine preosteoblast cell line cells and examine the possible pathogenesis of BRONJ. In the present study, the effect of ZA on the viability, apoptosis, differentiation and maturation of MC3T3-E1 cells, as well as its relevant molecular mechanism, were examined The results of a Cell Counting Kit 8 assay, a flow cytometric Annexin-V/propidium iodide assay and western blot analysis demonstrated that ZA exhibited a significant inhibition of cell viability and induction of apoptosis at concentrations >10 µM. Subsequently, the effect of ZA on cell differentiation at concentrations <1 µM were investigated. In this condition, ZA inhibited bone nodule formation and decreased the activity of alkaline phosphatase. The results of reverse transcription-quantitative polymerase chain reaction and western blot analyses indicated that ZA downregulated the expression levels of the marker genes and proteins associated with osteogenic differentiation. Further investigation revealed that the suppression of differentiation by ZA was associated with decreased expression of bone morphogenetic protein-2 (BMP-2) and downregulation of the phosphorylation levels in the downstream extracellular signal-regulated kinase 1/2 and p38 pathways. These adverse effects of ZA were observed to be concentration-dependent. The results from the present study suggested that ZA at higher concentrations induces cytotoxicity towards osteoblasts, and ZA at lower concentrations suppresses osteoblast differentiation by downregulation of BMP-2. These results assist in further understanding the mechanisms of BRONJ.

Mandibular inferior cortical bone thickness on panoramic radiographs in patients using bisphosphonates

OBJECTIVE

The goal of this study was to detect dimensional changes in the mandibular cortical bone associated with bisphosphonate (BP) use and to correlate measurements of the cortical bone with the cumulative dose of BPs.

STUDY DESIGN

Mandibular inferior cortical bone thickness (MICBT) was measured under the mental foramen on panoramic radiographs of patients with and without bisphosphonate-related osteonecrosis of the jaws (BRONJ) taking BPs and controls.

RESULTS

Patients with BRONJ had the highest mean MICBT (6.81 ± 1.35 mm), compared with patients without BRONJ taking BPs (5.44 ± 1.09 mm) and controls (4.79 ± 0.85 mm) (P < .01). Mean MICBT of patients with BRONJ was significantly higher than that of patients without BRONJ taking BPs. There was a correlation between MICBT and cumulative dose of zolendronate.

CONCLUSIONS

Measurement of MICBT on panoramic radiographs is a potentially useful tool for the detection of dimensional changes associated with BP therapy.