The dynamin inhibitor, dynasore, prevents zoledronate-induced viability loss in human gingival fibroblasts by partially blocking zoledronate uptake and inhibiting endosomal acidification.

OBJECTIVE: For treatment of medication-related osteonecrosis of the jaw, one proposed approach is the use of a topical agent to block entry of these medications in oral soft tissues. We tested the ability of phosphonoformic acid (PFA), an inhibitor of bisphosphonate entry through certain sodium-dependent phosphate contransporters (SLC20A1, 20A2, 34A1-3) as well as Dynasore, a macropinocytosis inhibitor, for their abilities to prevent zoledronate-induced (ZOL) death in human gingival fibroblasts (HGFs). METHODOLOGY: MTT assay dose-response curves were performed to determine non-cytotoxic levels of both PFA and Dynasore. In the presence of 50 µM ZOL, optimized PFA and Dynasore doses were tested for their ability to restore HGF viability. To determine SLC expression in HGFs, total HGF RNA was subjected to quantitative real-time RT-PCR. Confocal fluorescence microscopy was employed to see if Dynasore inhibited macropinocytotic HGF entry of AF647-ZOL. Endosomal acidification in the presence of Dynasore was measured by live cell imaging utilizing LysoSensor Green DND-189. As a further test of Dynasore's ability to interfere with ZOL-containing endosomal maturation, perinuclear localization of mature endosomes containing AF647-ZOL or TRITC-dextran as a control were assessed via confocal fluorescence microscopy with CellProfiler™ software analysis of the resulting photomicrographs. RESULTS: 0.5 mM PFA did not rescue HGFs from ZOL-induced viability loss at 72 hours while 10 and 30 µM geranylgeraniol did partially rescue. HGFs did not express the SLC transporters as compared to the expression in positive control tissues. 10 µM Dynasore completely prevented ZOL-induced viability loss. In the presence of Dynasore, AF647-ZOL and FITC-dextran co-localized in endosomes. Endosomal acidification was inhibited by Dynasore and perinuclear localization of both TRITC-dextran- and AF647-ZOL-containing endosomes was inhibited by 30 µM Dynasore. CONCLUSION: Dynasore prevents ZOL-induced viability loss in HGFs by partially interfering with macropinocytosis and by inhibiting the endosomal maturation pathway thought to be needed for ZOL delivery to the cytoplasm.

Effect of bisphosphonate on bone microstructure, mechanical strength in osteoporotic rats by ovariectomy.

BACKGROUND: Bisphosphonate (BP) can treat osteoporosis and prevent osteoporotic fractures in clinical. However, the effect of BP on microstructure and mechanical properties of cortical and trabecular bone has been taken little attention, separately. METHODS: In this study, BP was used to intervene in ovariectomized female SD rats. The femoral micro-CT images were used to measure the structural parameters and reconstruct the 3D models in volume of interest. The structural parameters of cortical and trabecular bone were measured, and the mechanical properties were predicted using micro-finite element analysis. RESULTS: There was almost no significant difference in the morphological structure parameters and mechanical properties of cortical bone between normal, ovariectomized (sham-OVX) and BP intervention groups. However, BP could significantly improve bone volume fraction (BV/TV) and trabecular separation (Tb.SP) in inter-femoral condyles (IT) (sham-OVX vs. BP, p < 0.001), and had no significant effect on BV/TV in medial and lateral femoral condyles (MT, LT). Similarly, BPs could significantly affect the effective modulus in IT (sham-OVX vs. BP, p < 0.001), and had no significant difference in MT and LT. In addition, the structural parameters and effective modulus showed a good linear correlation. CONCLUSION: In a short time, the effects of BP intervention and osteoporosis on cortical bone were not obvious. The effects of BP on trabecular bone in non-main weight-bearing area (IT) were valuable, while for osteoporosis, the main weight-bearing area (MT, LT) may improve the structural quality and mechanical strength of trabecular bone through exercise compensation.

Hydroxychloroquine and a low antiresorptive activity bisphosphonate conjugate prevent and reverse ovariectomy-induced bone loss in mice through dual antiresorptive and anabolic effects.

Osteoporosis remains incurable. The most widely used antiresorptive agents, bisphosphonates (BPs), also inhibit bone formation, while the anabolic agent, teriparatide, does not inhibit bone resorption, and thus they have limited efficacy in preventing osteoporotic fractures and cause some side effects. Thus, there is an unmet need to develop dual antiresorptive and anabolic agents to prevent and treat osteoporosis. Hydroxychloroquine (HCQ), which is used to treat rheumatoid arthritis, prevents the lysosomal degradation of TNF receptor-associated factor 3 (TRAF3), an NF-κB adaptor protein that limits bone resorption and maintains bone formation. We attempted to covalently link HCQ to a hydroxyalklyl BP (HABP) with anticipated low antiresorptive activity, to target delivery of HCQ to bone to test if this targeting increases its efficacy to prevent TRAF3 degradation in the bone microenvironment and thus reduce bone resorption and increase bone formation, while reducing its systemic side effects. Unexpectedly, HABP-HCQ was found to exist as a salt in aqueous solution, composed of a protonated HCQ cation and a deprotonated HABP anion. Nevertheless, it inhibited osteoclastogenesis, stimulated osteoblast differentiation, and increased TRAF3 protein levels in vitro. HABP-HCQ significantly inhibited both osteoclast formation and bone marrow fibrosis in mice given multiple daily PTH injections. In contrast, HCQ inhibited marrow fibrosis, but not osteoclast formation, while the HABP alone inhibited osteoclast formation, but not fibrosis, in the mice. HABP-HCQ, but not HCQ, prevented trabecular bone loss following ovariectomy in mice and, importantly, increased bone volume in ovariectomized mice with established bone loss because HABP-HCQ increased bone formation and decreased bone resorption parameters simultaneously. In contrast, HCQ increased bone formation, but did not decrease bone resorption parameters, while HABP also restored the bone lost in ovariectomized mice, but it inhibited parameters of both bone resorption and formation. Our findings suggest that the combination of HABP and HCQ could have dual antiresorptive and anabolic effects to prevent and treat osteoporosis.

Do bisphosphonates and RANKL inhibitors alter the progression of coronary artery calcification? A systematic review.

OBJECTIVES: To determine whether bisphosphonates and NF-κB ligand (RANKL) inhibitors delay coronary artery calcification (CAC). DESIGN: A systematic review was conducted. DATA SOURCES: MEDLINE, EMBASE and CENTRAL. ELIGIBILITY CRITERIA: Longitudinal studies investigating CAC progression in adults (>18 years) taking either a bisphosphonate or denosumab compared with those who did not. DATA EXTRACTION AND SYNTHESIS: Study and participant characteristics, and primary outcome ( ∆ CAC from baseline to follow-up) were extracted. The Risk Of Bias In Non-Randomised Studies-of Interventions (ROBINS-I) and Risk-of-Bias Tool for Randomised Trials (RoB2) tools were used to assess the risk of bias for observational and randomised controlled trials (RCTs), respectively. Outcome measures were reported. RESULTS: Four observational studies and one RCT (n=377) were included. Three studies solely reported the effect of bisphosphonates on ∆ CAC; one study (n=56) demonstrated a statistically significant CAC reduction in the intervention group (-372 mm3/year) compared with control (+159 mm3/year) (p<0.01). One study (n=14) demonstrated a difference in ∆ CAC between intervention (+880 mm3/year) versus control (+2220 mm3/year), however, no p value comparing groups was reported. One study (n=115) found no statistically significant difference between intervention and control.One study (n=42) exclusively investigated the effect of RANKL on ∆ CAC; there was a statistically significant reduction in CAC at 6-month follow-up between intervention (-133±124 modified Agatston unit (AU)) and control (+188±72 modified AU), p=0.03.One study (n=150) compared both bisphosphonates and denosumab to control and found no statistically significant difference between either intervention group and control over 24 months. Meta-analysis was not performed due to limited, heterogeneous studies. CONCLUSIONS: There is insufficient evidence supporting the correlation between bisphosphonate or RANKL inhibitor use and CAC progression. Further research is warranted.

Increased bone mass but delayed mineralization: in vivo and in vitro study for zoledronate in bone regeneration.

BACKGROUND: Bisphosphonates (BPs) are widely used to inhibit excessive osteoclast activity. However, the potential to compromise bone defect healing has limited their broader application. To better understand the influence of BPs on bone regeneration, we established a bone grafting model with Zoledronate administration, aiming to deepen the understanding of bone remodeling and mineralization processes. METHODS: A bone grafting model was established in the distal femurs of male Sprague-Dawley rats. The experimental group received systemic administration of Zoledronate (ZOL, 0.2 mg/kg, administered twice). Histological analysis and immunohistochemistry (IHC) were employed to assess osteoblastic and macrophage activity, tartrate-resistant acid phosphatase (TRAP) staining was used to evaluate osteoclastogenesis. Mineralization was assessed through Micro-CT analysis, Raman spectroscopy, and back-scatter scanning electron microscopy (BSE-SEM). Additionally, the in vitro effects of ZOL on osteoblast and osteoclast activity were investigated to further elucidate its impact on bone regeneration. RESULTS: In vivo, the ZOL group showed increased bone mass, as observed in histological and radiological assessments. However, Micro-CT, Raman spectroscopy, and BSE-SEM detection revealed lower mineralization levels in ZOL group's regenerated bone. Acid-etched SEM analysis showed abnormal osteocyte characteristics in ZOL-group's regenerated bone. Simultaneously, elevated osteopontin (OPN), F4/80 expression along with reduced TRAP expressing was found in the grafting region of ZOL group. In vitro, ZOL did not negatively impact osteogenetic activity (ALP, BMP4, OCN expression) at the tested concentrations (0.02-0.5 g/ml) but significantly impaired mineralization and inhibited osteoclast formation, even at the lowest concentration. CONCLUSIONS: This study highlights a less recognized negative effect of ZOL on bone mineralization during bone regeneration. More research is needed to elucidate the underlying mechanism.

Impact of anti-fracture medications on bone material and strength properties: a systematic review and meta-analysis.

Background and aims: Reduced bone mineral density (BMD) and microarchitectural deterioration contribute to increased fracture risk. Although the effects of anti-fracture medications (AFMs) on BMD are well-documented, their impact on bone material properties (BMPs) remains poorly characterized. Accordingly, we conducted a systematic review and meta-analysis to evaluate the effects of AFMs on BMPs. Based on data availability, we further categorized AFMs into anti-resorptives, bisphosphonates alone, and strontium ranelate subgroups to perform additional analyses of BMPs in osteoporotic patients. Methods: We did a comprehensive search of three databases, namely, PubMed, Web of Science, and Google Scholar, using various permutation combinations, and used Comprehensive Meta-Analysis software to analyze the extracted data. Results: The 15 eligible studies (randomized and non-randomized) compared the following: (1) 301 AFM-treated patients with 225 on placebo; (2) 191 patients treated with anti-resorptives with 131 on placebo; (3) 86 bisphosphonate-treated patients with 66 on placebo; and (4) 84 strontium ranelate-treated patients with 70 on placebo. Pooled analysis showed that AFMs significantly decreased cortical bone crystallinity [standardized difference in means (SDM) -1.394] and collagen maturity [SDM -0.855], and collagen maturity in cancellous bone [SDM -0.631]. Additionally, anti-resorptives (bisphosphonates and denosumab) significantly increased crystallinity [SDM 0.387], mineral-matrix ratio [SDM 0.771], microhardness [SDM 0.858], and contact hardness [SDM 0.952] of cortical bone. Anti-resorptives increased mineral-matrix ratio [SDM 0.543] and microhardness [SDM 0.864] and decreased collagen maturity [SDM -0.539] in cancellous bone. Restricted analysis of only bisphosphonate-treated studies showed a significant decrease in collagen maturity [SDM -0.650] in cancellous bone and an increase in true hardness [SDM 1.277] in cortical bone. In strontium ranelate-treated patients, there was no difference in BMPs compared to placebo. Conclusion: Collectively, our study suggests that AFMs improve bone quality, which explains their anti-fracture ability that is not fully accounted for by increased BMD in osteoporosis patients.

Evaluation of Methenolone Enanthate Efficacy in Preventing MRONJ: A Randomized Trial on Rats.

BACKGROUND: It is well-known that oral surgical procedures pose a high risk for medication-related osteonecrosis of the jaw in patients taking bisphosphonates. Although some position papers and guidelines have been published with regard to its treatment, few studies have investigated prevention methods. This study investigates the effectiveness of methenolone enanthate, an anabolic steroid, for the prevention of medication-related osteonecrosis of the jaw. METHODS: Thirty-six Wistar rats were divided into three groups. Two experimental groups, Z and ZM, took zoledronic acid for 6 weeks prior to extraction of the left maxillary first molar. The Group ZM also was given methenolone enanthate continuously for 1 week before and 4 weeks after the extraction. The control group was not given any medication. The rats were euthanized 5 weeks after extraction. The extraction socket was evaluated clinically for bone exposure and histologically for inflammation, hyperemia, collagen fibers, epithelialization, number of osteoclasts, and empty lacunae. RESULTS: Six rats died during the experimental research. The bone exposure rate, mean numbers of attached osteoclasts (in 40× magnification), and empty lacunae (in 100× magnification) were 0%, 4%, and 0.8% in Group C; 75%, 1%, and 8% in Group Z; and 10%, 2.1%, and 3% in Group ZM, respectively. Significant differences exist between all groups regarding the number of empty lacunae. There were significant differences between Group C/ZM and Group Z in terms of bone exposure rate, inflammation, hyperemia, collagen fiber organization, and epithelialization. CONCLUSION: In our tested preclinical model, methenolone enanthate has shown potential for preventing medication-related osteonecrosis of the jaw.

The Case for Bisphosphonate Use in Astronauts Flying Long-Duration Missions.

Changes in the structure of bone can occur in space as an adaptive response to microgravity and on Earth due to the adaptive effects to exercise, to the aging of bone cells, or to prolonged disuse. Knowledge of cell-mediated bone remodeling on Earth informs our understanding of bone tissue changes in space and whether these skeletal changes might increase the risk for fractures or premature osteoporosis in astronauts. Comparisons of skeletal health between astronauts and aging humans, however, may be both informative and misleading. Astronauts are screened for a high level of physical fitness and health, are launched with high bone mineral densities, and perform exercise daily in space to combat skeletal atrophy as an adaptive response to reduced weight-bearing function, while the elderly display cellular and tissue pathology as a response to senescence and disuse. Current clinical testing for age-related bone change, applied to astronauts, may not be sufficient for fully understanding risks associated with rare and uniquely induced bone changes. This review aims to (i) highlight cellular analogies between spaceflight-induced and age-related bone loss, which could aid in predicting fractures, (ii) discuss why overreliance on terrestrial clinical approaches may miss potentially irreversible disruptions in trabecular bone microarchitecture induced by spaceflight, and (iii) detail how the cellular effects of the bisphosphonate class of drugs offer a prophylactic countermeasure for suppressing the elevated bone resorption characteristically observed during long-duration spaceflights. Thus the use of the bisphosphonate will help protect the bone from structural changes while in microgravity either along with exercise or alone when exercise is not performed, e.g. after an injury or illness.

Calcium-mediated zoledronate loading onto carbon nanohorns.

Previously, we showed that the anti-osteoclast effect of zoledronate (ZOL), a type of bisphosphonate, is enhanced when it is used as a nanocomposite comprising ZOL, an "oxidized single-walled carbon nanohorn (OxCNH) with a spherical shape" and calcium phosphate (CaP). This nanocomposite, termed OxCNH-CaP-ZOL, is a potential therapeutic agent for patients with bone fragility associated with metastatic bone cancer. Because OxCNH-CaP-ZOL contains by-products that comprise CaP-ZOL nanocomposites, the aim of this study was to prepare more sophisticated nanocomposites lacking such by-products; it was achieved by reducing the availability of calcium and phosphate ions during the preparation process. In this new nanocomposite, ZOL loading onto OxCNH was mediated by Ca, and therefore it is referred to as OxCNH-Ca-ZOL. Because the amount of ZOL in OxCNH-Ca-ZOL was about half that in OxCNH-CaP-ZOL and murine macrophages (RAW264.7 cells) took up less OxCNH-Ca-ZOL than OxCNH-CaP-ZOL, the amount of ZOL inside RAW264.7 cells exposed to OxCNH-Ca-ZOL was less than that inside cells exposed to OxCNH-CaP-ZOL. Despite this drawback, OxCNH-Ca-ZOL had suppressive effects similar to OxCNH-CaP-ZOL on the viability of RAW264.7 cells. The reason for these phenomena is not clear; however, it could be due to the differences in the ZOL release rate between OxCNH-Ca-ZOL and OxCNH-CaP-ZOL. In addition, receptor activator of nuclear factor kappa-B ligand (RANKL)-induced differentiation of RAW264.7 cells into osteoclasts was suppressed by co-administration of RANKL with OxCNH-Ca-ZOL as effectively as with OxCNH-CaP-ZOL, and indeed, their effects were greater than those of free ZOL.

[Dynamics of mandibular density during therapy with zolendronic acid]. / Dinamika plotnosti nizhnei chelyusti v protsesse terapii zolendronovoi kislotoi.

THE AIM OF THE STUDY: Was to investigate the dynamics of mandibular density in cancer patients during therapy with zolendronic acid. MATERIALS AND METHODS: The study comprised 14 patients who received zolendronic acid at a dosage of 4 mg once every 28 days for bone metastases. In all 14 patients, measurements of mandibular density values on CT scans were performed over time. RESULTS: Using multiple linear regression analysis, a model was developed to predict the effect of the number of zolendronic acid injections «X1¼ on the dynamics of mandibular density «Y¼. The resulting formula for predicting mandibular density is Y = 5.9 X1 + 49 HU. CONCLUSION: The model has limitations due to the study design but still can be used by oncologists and dentists to assess mandibular density in patients taking zolendronic acid.

Macrophage Polarization during MRONJ Development in Mice.

Macrophages are important regulators of bone remodeling, and M1 polarization is observed in the setting of medication-related osteonecrosis of the jaws (MRONJ). Here, we characterize the phenotype of macrophages during early stages of MRONJ development in zoledronate (ZA)-treated mice with periodontal disease and explore the role of rosiglitazone, a drug that has been reported to lower the M1/M2 macrophage ratio, in MRONJ burden. Mice received ZA, and experimental periodontal disease (EPD) was induced around their second left maxillary molar. The mice were euthanized 1, 2, or 4 wk later. Micro-computed tomography and histologic and immunohistochemical analyses were carried out. In a separate experiment, mice were treated with ZA in the absence or presence of rosiglitazone, EPD was induced for 5 wk, and the MRONJ burden was assessed. An M1 predilection was noted in ZA versus vehicle (Veh) mice at 1, 2, or 4 wk after ligature placement. M1 cells were found to be positive for MMP-13, and their presence coincided with disruption of the surrounding collagen network in ZA mice. Rosiglitazone caused a reversal in the M1/M2 polarization in Veh and ZA mice. Rosiglitazone did not cause significant radiographic changes 5 wk after EPD in Veh or ZA animals. Importantly, percentage osteonecrosis and bone exposure were decreased in the rosiglitazone-treated versus nontreated ZA sites 5 wk after EPD. Our data point to an important role of M1 macrophage polarization with an overexpression of MMP-13 in the early phases of MRONJ development and provide insight into the use of interventional approaches promoting an M2 phenotype as a preventative means to alleviate MRONJ burden.

Development and Characterization of a Peptide-Bisphosphonate Nanoparticle for the Treatment of Breast Cancer.

In women, breast cancer (BC) is the most common cancer, and despite advancements in diagnosis and treatment, 20-30% of early stage BC patients develop metastatic disease. Metastatic BC is deemed an incurable disease, which accounts for 90% of BC related deaths, with only 26% of metastatic patients reaching a 5 year survival rate. Therefore, there is an unmet need for the prevention or treatment of metastasis in early stage breast cancer patients. Bisphosphonates (BPs) are potent inhibitors of bone resorption and are extensively used for the prevention of osteoporosis and other skeletal disorders, as well as for the treatment of secondary bone cancer in BC patients. Furthermore, the direct anticancer activity of BPs has been established in primary tumor models. However, these studies were limited by the need for dosages far above the clinical range to overcome BPs' high affinity for bones and poor accumulation in the tumor itself, which leads to toxicity, including osteonecrosis of the jaw. To decrease BP dosage, increase bioavailability, and direct anticancer activity, we used the RALA (R-) peptide delivery system to form highly stable NPs with the nitrogen containing BP, risedronate (R-RIS). In vitro studies showed that, in comparison to RIS, R-RIS nanoparticles increased cytotoxicity and reduced metastatic features such as proliferation, migration, invasion, and adhesion of metastatic BC cells to bones. Furthermore, in an in vivo model, R-RIS had increased tumor accumulation while still maintaining similar bone accumulation to RIS alone. This increase in tumor accumulation corresponded with decreased tumor volume and lungs metastasis. R-RIS has great potential to be used in combination with standard of care chemotherapy for the treatment of primary BC and its metastasis while still having its bone resorption inhibiting properties.

Influence of zoledronic acid and low-intensity laser on collagen fibers during the bone repair process.

PURPOSE: To evaluate collagen fibers during the bone repair process in critical defects created in the tibias of rats, treated with zoledronic acid (AZ) associated with low-level laser therapy (LLLT). METHODS: Ten rats were distributed according to treatment: group 1) saline solution; group 2) LLLT; group 3) AZ; group 4) AZ and LLLT. AZ was administered at the dose of 0.035 mg/kg at fortnightly intervals over eight weeks. Next, 2-mm bone defects were created in the tibias of all animals. The bone defects in groups 2 and 4 were irradiated LLLT in the immediate postoperative period. After periods 14 and 28 of application, the animals were euthanized, and birefringence analysis was performed. RESULTS: Approximately 90% of the total area was occupied by collagen fibers within the red color spectrum, this area being statistically larger in relation to the area occupied by collagen fibers within the green and yellow spectrum, in the four groups. Over the 14-day period, there was no statistically significant difference between the groups. In the 28-day period, group 2 (14.02 ± 15.9%) was superior in quantifying green birefringent fibers compared to group 1 (3.06 ± 3.24%), with p = 0.009. CONCLUSIONS: LLLT associated with ZA is effective in stimulating the neoformation of collagen fibers. The LLLT group without the association with ZA showed a greater amount of immature and less organized matrix over a period of 28 days.

Determination of bisphosphonate properties in terms of bioavailability, bone affinity, and cytotoxicity.

BACKGROUND: The study aimed to evaluate the therapeutic potential of fourteen newly synthesized bisphosphonates by assessing their bioavailability, bone affinity, and cytotoxicity. These bisphosphonates included a series of aminomethylenebisphosphonates and standard compounds such as risedronate and tiludronate. METHODS: Drug permeability was determined using Parallel Artificial Membrane Permeability Assays (PAMPA), while bone affinity was assessed by sorption on hydroxyapatite. Bacterial cell response to the bisphosphonates was also examined using Lactobacillus paracasei cells as a model. RESULTS: Several tested compounds, including BP3 to BP8 and BP11, which feature substituents in the pyridine ring such as methyl groups, iodine, bromine, chlorine, or hydroxyl groups, demonstrated potentially more beneficial therapeutic properties than commercially used bisphosphonates. These compounds showed stronger bone affinity and higher gastrointestinal absorption with comparable or lower cytotoxic effects. Specifically, BP11 exhibited the highest bone affinity, while BP8 and BP11 showed the greatest permeability. CONCLUSIONS: The findings suggest that BP3 BP8, and BP11 are promising candidates for further research. These results highlight the importance of comprehensively evaluating bisphosphonates' therapeutic properties to identify effective treatments for osteoporosis and other bone diseases.

LL-37 and bisphosphonate co-delivery 3D-scaffold with antimicrobial and antiresorptive activities for bone regeneration.

This study introduces a novel 3D scaffold for bone regeneration, composed of silk fibroin, chitosan, nano-hydroxyapatite, LL-37 antimicrobial peptide, and pamidronate. The scaffold addresses a critical need in bone tissue engineering by simultaneously combating bone infections and promoting bone growth. LL-37 was incorporated for its broad-spectrum antimicrobial properties, while pamidronate was included to inhibit bone resorption. The scaffold's porous structure, essential for cell infiltration and nutrient diffusion, was achieved through a freeze-drying process. In vitro assessments using SEM and FTIR confirmed the scaffold's morphology and chemical integrity. Antimicrobial efficacy was tested against pathogens of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa). In vivo studies in a murine model of infectious bone defect revealed the scaffold's effectiveness in reducing inflammation and bacterial load, and promoting bone regeneration. RNA sequencing of treated specimens provided insights into the molecular mechanisms underlying these observations, revealing significant gene expression changes related to bone healing and immune response modulation. The results indicate that the scaffold effectively inhibits bacterial growth and supports bone cell functions, making it a promising candidate for treating infectious bone defects. Future studies should focus on optimizing the release of therapeutic agents and evaluating the scaffold's clinical potential.

Farnesyl pyrophosphate synthase inhibitors with antiosteoporosis efficacy in ovariectomized rats: A mixed binding approach beyond bisphosphonates.

The primary focus of bisphosphonate medications is on targeting human farnesyl pyrophosphate synthase (hFPPS), an essential regulator of mammalian isoprenoids. Yet, these drugs encounter limitations due to their restricted "druglike" properties and their effectiveness primarily in treating skeletal disorders. In this study, we synthesized novel non-bisphosphonate compounds, using 4,4'-(ethane-1,2-diylbis(oxy))bis(3-methoxybenzaldehyde) (1) as a starting compound, with the aim of targeting hFPPS through a mixed binding approach. Among the various compounds tested, compounds 4a and 4b exhibited significant inhibition of hFPPS activity, with IC50 values of 1.108 and 1.24 µM, respectively. Docking studies further revealed that both compounds bound within the allylic binding site and near the isopentenyl diphosphate (IPP) site within the hFPPS pocket. Molecular dynamic simulations were performed on the best docking pose of the most potent compound 4a to confirm the formation of a stable complex with hFPPS. In an in vivo study conducted on ovariectomized rats, various biochemical markers including osteocalcin, estradiol, osteoprotegerin, bone mineral content, and density were negatively impacted, while levels of bone specific alkaline phosphatase, receptor activator of nuclear factor kappa-Β ligand, serum/urinary calcium, and phosphate increased. Notably, compound 4a exhibited antiresorptive properties similar to zoledronate, effectively restoring most of the perturbed biochemical estimations. These findings suggest the potential of compound 4a, a non-bisphosphonate compound, as alternative therapeutic agents for combating osteoporosis.

Role of sclerostin deletion in bisphosphonate-induced osteonecrosis of the jaw.

PURPOSE: Bone resorption inhibitors, such as bisphosphonates (BP) and denosumab, are frequently used for the management of osteoporosis. Although both drugs reduce the risk of osteoporotic fractures, they are associated with a serious side effect known as medication-related osteonecrosis of the jaw (MRONJ). Sclerostin antibodies (romosozumab) increase bone formation and decrease the risk of osteoporotic fractures: however, their anti-resorptive effect increases ONJ. Thus, this study aimed to elucidate the role of sclerostin deletion in the development of MRONJ. METHODS: Sclerostin knockout (SostΔ26/Δ26) mice were used to confirm the development of ONJ by performing tooth extractions. To confirm the role of sclerostin deficiency in a more ONJ-prone situation, we used the BP-induced ONJ model in combination with severe periodontitis to evaluate the development of ONJ and bone formation in wild-type (WT) and SostΔ26/Δ26 mice. Wound healing assay using gingival fibroblasts with or without sclerostin stimulation and tooth extraction socket healing were evaluated in the WT and SostΔ26/Δ26 mice. RESULTS: ONJ was not detected in the extraction socket of SostΔ26/Δ26 mice. Moreover, the incidence of ONJ was significantly lower in the SostΔ26/Δ26 mice treated with BP compared to that of the WT mice. Osteogenic proteins, osteocalcin, and runt-related transcription factor 2, were expressed in the bone surface in SostΔ26/Δ26 mice. Recombinant sclerostin inhibited gingival fibroblast migration. The wound healing rate of the extraction socket was faster in SostΔ26/Δ26 mice than in WT mice. CONCLUSION: Sclerostin deficiency did not cause ONJ and reduced the risk of developing BP-induced ONJ. Enhanced bone formation and wound healing were observed in the tooth extraction socket. The use of romosozumab (anti-sclerostin antibody) has proven to be safe for surgical procedures of the jaw.

Preventing bisphosphonate induced osteonecrosis of the jaw with a polyguanidine conjugate (GuaDex): A promising new approach.

Osteonecrosis of the jaw (ONJ) is a relatively rare side effect after prolonged use of bisphosphonates, which are drugs used to treat bone resorption in osteoporosis and certain cancers. This study introduces a novel ONJ model in rats by combining exposure to bisphosphonates, oral surgery, and bacterial inoculation. Potential ONJ preventive effects of polyguanidine (GuaDex) or antibiotics were evaluated. The study consisted of twenty-four male Wistar rats were divided into four groups. Groups 1 to 3 were given weekly doses of i.v. Zoledronic acid (ZA), four weeks before and two weeks after an osteotomy procedure on their left mandibular first molar. Group 4 was a negative control. Streptococcus gordonii bacteria were introduced into the osteotomy pulp chamber and via the food for seven days. On day eight, the rats were given different treatments. Group 1 was given a GuaDex injection into the osteotomy socket, Group 2 was given an intramuscular (i.m.) injection of clindamycin, Group 3 (positive control) was given an i.m. injection of saline, and Group 4 was given an i.m. injection of saline. Blood samples were taken two weeks after the osteotomy procedure, after which the rats were euthanized. Bone healing, bone mineral density, histology, and blood status were analyzed. The results showed that Group 1 (GuaDex) had no ONJ, extensive ongoing bone regeneration, active healing activity, vascularization, and no presence of bacteria. Group 2 (clindamycin) showed early stages of ONJ, avascular areas, and bacteria. Group 3 showed stages of ONJ, inflammatory infiltrates, defective healing, and bacterial presence, and Group 4 had normal healing activity and no bacterial presence. Conclusion: ZA treatment and bacterial inoculation after tooth extraction inhibited bone remodeling/healing and induced ONJ characteristic lesions in the rats. Only GuaDex apparently prevented ONJ development, stimulated bone remodeling, and provided an antimicrobial effect.

Effects of daily teriparatide, weekly high-dose teriparatide, or bisphosphonate on cortical and trabecular bone of vertebra and proximal femur in postmenopausal women with fragility fracture: Sub-analysis by quantitative computed tomography from the TERABIT study.

PURPOSE: The effects of daily teriparatide (D-PTH, 20 µg/day), weekly high-dose teriparatide (W-PTH, 56.5 µg/week), or bisphosphonate (BP) on the vertebra and proximal femur were investigated using quantitative computed tomography (QCT). METHODS: A total of 131 postmenopausal women with a history of fragility fractures were randomized to receive D-PTH, W-PTH, or bisphosphonate (oral alendronate or risedronate). QCT were evaluated at baseline and after 18 months of treatment. RESULTS: A total of 86 participants were evaluated by QCT (Spine: D-PTH: 25, W-PTH: 21, BP: 29. Hip: PTH: 22, W-PTH: 21, BP: 32. Dropout rate: 30.5 %). QCT of the vertebra showed that D-PTH, W-PTH, and BP increased total vBMD (+34.8 %, +18.2 %, +11.1 %), trabecular vBMD (+50.8 %, +20.8 %, +12.2 %), and marginal vBMD (+20.0 %, +14.0 %, +11.5 %). The increase in trabecular vBMD was greater in the D-PTH group than in the W-PTH and BP groups. QCT of the proximal femur showed that D-PTH, W-PTH, and BP increased total vBMD (+2.8 %, +3.6 %, +3.2 %) and trabecular vBMD (+7.7 %, +5.1 %, +3.4 %), while only W-PTH and BP significantly increased cortical vBMD (-0.1 %, +1.5 %, +1.6 %). Although there was no significant increase in cortical vBMD in the D-PTH group, cortical bone volume (BV) increased in all three treatment groups (+2.1 %, +3.6 %, +3.1 %). CONCLUSIONS: D-PTH had a strong effect on trabecular bone of vertebra. Although D-PTH did not increase cortical BMD of proximal femur, it increased cortical BV. W-PTH had a moderate effect on trabecular bone of vertebra, while it increased both cortical BMD and BV of proximal femur. Although BP had a limited effect on trabecular bone of vertebra compared to teriparatide, it increased both cortical BMD and BV of proximal femur.

Lead Acetate-Injected Mice is an Animal Model for Extrapolation of Calcifying Response to Humans Due to Low Involvement of Bone Resorption.

Vascular calcification affects the prognosis of patients with renal failure. Bisphosphonates are regarded as candidate anti-calcifying drugs because of their inhibitory effects on both calcium-phosphate aggregation and bone resorption. However, calcification in well-known rodent models is dependent upon bone resorption accompanied by excessive bone turnover, making it difficult to estimate accurately the anti-calcifying potential of drugs. Therefore, models with low bone resorption are required to extrapolate anti-calcifying effects to humans. Three bisphosphonates (etidronate, alendronate, and FYB-931) were characterised for their inhibitory effects on bone resorption in vivo and calcium-phosphate aggregation estimated by calciprotein particle formation in vitro. Then, their effects were examined using two models inducing ectopic calcification: the site where lead acetate was subcutaneously injected into mice and the transplanted, aorta obtained from a donor rat. The inhibitory effects of bisphosphonates on bone resorption and calcium-phosphate aggregation were alendronate > FYB-931 > etidronate and FYB-931 > alendronate = etidronate, respectively. In the lead acetate-induced model, calcification was most potently suppressed by FYB-931, followed by alendronate and etidronate. In the aorta-transplanted model, only FYB-931 suppressed calcification at a high dose. In both the models, no correlation was observed between calcification and bone resorption marker, tartrate-resistant acid phosphatase (TRACP). Results from the lead acetate-induced model showed that inhibitory potency against calcium-phosphate aggregation contributed to calcification inhibition. The two calcification models, especially the lead acetate-induced model, may be ideal for the extrapolation of calcifying response to humans because of calcium-phosphate aggregation rather than bone resorption as its mechanism.