A patent review of bisphosphonates in treating bone disease

Geranylgeranyl diphosphate synthase inhibition impairs osteoclast differentiation, morphology, and resorptive activity

Nitrogen bisphosphonates, such as zoledronic acid, target the enzyme farnesyl diphosphate synthase (FDPS) in the isoprenoid biosynthetic pathway (IBP), and are the frontline treatment for osteolytic bone diseases. A strong affinity of these agents for bone limits their distribution out of the skeleton. Geranylgeranyl diphosphate synthase (GGDPS) is directly downstream to FDPS in the IBP and novel GGDPS inhibitors such as RAM2061 have been shown to have key drug-like features including prolonged half-life, metabolic stability, and systemic distribution. Furthermore, RAM2061 exerts anti-neoplastic benefits in mouse models of multiple myeloma and Ewing sarcoma. Therefore, we are interested in determining the potential impact of RAM2061 on osteoclast biology and bone remodeling. Studies utilizing undifferentiated RAW264.7 cells demonstrated that treatment with RAM2061 depletes cells of geranylgeranyl diphosphate, impairs protein geranylgeranylation, and induces markers of the unfolded protein response pathway and apoptosis. Differentiation of RAW264.7 cells to mature osteoclasts is disrupted by RAM2061, resulting in decreased numbers of mature osteoclasts, altered morphology, and decreased tartrate-resistant acid phosphatase activity. Treatment of fully differentiated RAW264.7 cells with RAM2061 led to decreased resorptive activity. Confocal microscopy studies revealed that RAM2061 disrupts Cdc42 localization, inhibiting proper actin ring formation in osteoclasts. No significant impact on bone turnover markers or bone histomorphology was observed following a 3-week treatment of CD-1 mice with RAM2061, although decreased numbers of osteoclasts were observed. Liquid chromatography-tandem mass spectrometry studies confirmed accumulation of RAM2061 in bone from the in vivo studies as well as hydroxyapatite binding in vitro. In conclusion, these studies are the first to demonstrate the anti-osteoclastic activity of GGDPS inhibitor treatment and support future studies exploring the therapeutic benefit of this novel therapy in the setting of pathological bone remodeling.

Organoselenium Compounds: Chemistry and Applications in Organic Synthesis

Selenium, originally described as a toxin, turns out to be a crucial trace element for life that appears as selenocysteine and its dimer, selenocystine. From the point of view of drug developments, selenium-containing drugs are isosteres of sulfur and oxygen with the advantage that the presence of the selenium atom confers antioxidant properties and high lipophilicity, which would increase cell membrane permeation leading to better oral bioavailability. In this article, we have focused on the relevant features of the selenium atom, above all, the corresponding synthetic approaches to access a variety of organoselenium molecules along with the proposed reaction mechanisms. The preparation and biological properties of selenosugars, including selenoglycosides, selenonucleosides, selenopeptides, and other selenium-containing compounds will be treated. We have attempted to condense the most important aspects and interesting examples of the chemistry of selenium into a single article.

Prevalence of dental alterations in patients under bisphosphonates therapy: a systematic review

This systematic review aimed to estimate the prevalence and describe dentoalveolar lesions associated with bisphosphonates therapy. A systematic review of the literature was conducted using the following databases: PubMed, Embase, Cochrane, CINAHL, Scopus, Web of Science, Lilacs, SciElo, and Grey Literature. Quality of individual studies analysis was performed by using Newcastle-Ottawa Scale. Certainty of cumulative evidence was achieved by applying Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. The software R Statistics version 4.0.5 (The R Foundation) was used for proportion estimations per study and corresponding confidence intervals were estimated through the Clopper-Pearson method. Four articles were included for the qualitative synthesis. Two studies were considered of good quality, one of fair, and one of poor quality. A total of 231 patients were encompassed. Widening of the periodontal ligament space (22.2-39.7%), periradicular radiolucencies (20-22.9%), and pulp calcifications (33.3-69.2%) were the most frequent alterations. Certainty of evidence was rated as very low. Based on limited evidence, this systematic review reports a variety of dentoalveolar alterations in patients under bisphosphonate therapy. These features might impact on dental clinical practice. However, the level of evidence is considered very low due to important limitations.

Pharmacological options in the treatment of osteogenesis imperfecta: A comprehensive review of clinical and potential alternatives

Osteogenesis imperfecta (OI) is a genetically heterogeneous connective tissue disorder characterized by bone fragility and different extra-skeletal manifestations. The severity of these manifestations makes it possible to classify OI into different subtypes based on the main clinical features. This review aims to outline and describe the current pharmacological alternatives for treating OI, grounded on clinical and preclinical reports, such as antiresorptive agents, anabolic agents, growth hormone, and anti-TGFβ antibody, among other less used agents. The different options and their pharmacokinetic and pharmacodynamic properties will be reviewed and discussed, focusing on the variability of their response and the molecular mechanisms involved to attain the main clinical goals, which include decreasing fracture incidence, improving pain, and promoting growth, mobility, and functional independence.

In silico identification of potential phytochemical inhibitors targeting farnesyl diphosphate synthase of cotton bollworm (Helicoverpa armigera)

Helicoverpa armigera (Ha), a polyphagous pest, causes significant damage to several crop plants, including cotton. The control of this cosmopolitan pest is largely challenging due to the development of resistance to existing management practices. The Juvenile Hormone (JH) plays a pivotal role in the life cycle of insects by regulating their morphogenetic and gonadotropic development. Hence, enzymes involved in JH biosynthesis are an attractive target for the development of selective insecticides. Farnesyl diphosphate synthase (FPPS), a member protein of (E)-prenyl-transferases, is one of the most crucial enzymes in the biosynthetic pathway of JHs. It catalyzes the condensation of isopentenyl diphosphate (IPP) with dimethylallyl diphosphate (DMAPP), forming farnesyl diphosphate (FPP), a precursor of JH. The study was designed to identify an effective small inhibitory molecule that could inhibit the activity of Helicoverpa armigera - FPPS (HaFPPS) for an effective pest control intervention. Therefore, a 3D model of FPPS protein was generated using homology modeling. The FooDB database library of small molecules was selected for virtual screening, following which binding affinities were evaluated using docking studies. Three top-scored molecules were analyzed for various pharmacophore properties. Further, molecular dynamics (MD) simulation analysis showed that the identified molecules (mitraphylline-ZINC1607834, chlorogenic acid-ZINC2138728 and llagate-ZINC3872446) had a reasonably acceptable binding affinity for HaFPPS and resulted in the formation of a stable HaFPPS-inhibitor(s) complex. The identified phytochemical molecules may be used as potent inhibitors of HaFPPS thus, paving the way for further developing environment-friendly insect growth regulator(s). Communicated by Ramaswamy H. Sarma.

A 3D-printed molybdenum-containing scaffold exerts dual pro-osteogenic and anti-osteoclastogenic effects to facilitate alveolar bone repair

The positive regulation of bone-forming osteoblast activity and the negative feedback regulation of osteoclastic activity are equally important in strategies to achieve successful alveolar bone regeneration. Here, a molybdenum (Mo)-containing bioactive glass ceramic scaffold with solid-strut-packed structures (Mo-scaffold) was printed, and its ability to regulate pro-osteogenic and anti-osteoclastogenic cellular responses was evaluated in vitro and in vivo. We found that extracts derived from Mo-scaffold (Mo-extracts) strongly stimulated osteogenic differentiation of bone marrow mesenchymal stem cells and inhibited differentiation of osteoclast progenitors. The identified comodulatory effect was further demonstrated to arise from Mo ions in the Mo-extract, wherein Mo ions suppressed osteoclastic differentiation by scavenging reactive oxygen species (ROS) and inhibiting mitochondrial biogenesis in osteoclasts. Consistent with the in vitro findings, the Mo-scaffold was found to significantly promote osteoblast-mediated bone formation and inhibit osteoclast-mediated bone resorption throughout the bone healing process, leading to enhanced bone regeneration. In combination with our previous finding that Mo ions participate in material-mediated immunomodulation, this study offers the new insight that Mo ions facilitate bone repair by comodulating the balance between bone formation and resorption. Our findings suggest that Mo ions are multifunctional cellular modulators that can potentially be used in biomaterial design and bone tissue engineering.

Vascular Calcification in Chronic Kidney Disease: An Update and Perspective

Chronic kidney disease is a devastating condition resulting from irreversible loss of nephron numbers and function and leading to end-stage renal disease and mineral disorders. Vascular calcification, an ectopic deposition of calcium-phosphate salts in blood vessel walls and heart valves, is an independent risk factor of cardiovascular morbidity and mortality in chronic kidney disease. Moreover, aging and related metabolic disorders are essential risk factors for chronic kidney disease and vascular calcification. Marked progress has been recently made in understanding and treating vascular calcification in chronic kidney disease. However, there is a paucity of systematic reviews summarizing this progress, and investigating unresolved issues is warranted. In this systematic review, we aimed to overview the underlying mechanisms of vascular calcification in chronic kidney diseases and discuss the impact of chronic kidney disease on the pathophysiology of vascular calcification. Additionally, we summarized potential clinical diagnostic biomarkers and therapeutic applications for vascular calcification with chronic kidney disease. This review may offer new insights into the pathogenesis, diagnosis, and therapeutic intervention of vascular calcification.

Bisphosphonates: The role of chemistry in understanding their biological actions and structure-activity relationships, and new directions for their therapeutic use

The bisphosphonates ((HO)2P(O)CR1R2P(O)(OH)2, BPs) were first shown to inhibit bone resorption in the 1960s, but it was not until 30 years later that a detailed molecular understanding of the relationship between their varied chemical structures and biological activity was elucidated. In the 1990s and 2000s, several potent bisphosphonates containing nitrogen in their R2 side chains (N-BPs) were approved for clinical use including alendronate, risedronate, ibandronate, and zoledronate. These are now mostly generic drugs and remain the leading therapies for several major bone-related diseases, including osteoporosis and skeletal-related events associated with bone metastases. The early development of chemistry in this area was largely empirical and only a few common structural features related to strong binding to calcium phosphate were clear. Attempts to further develop structure-activity relationships to explain more dramatic pharmacological differences in vivo at first appeared inconclusive, and evidence for mechanisms underlying cellular effects on osteoclasts and macrophages only emerged after many years of research. The breakthrough came when the intracellular actions on the osteoclast were first shown for the simpler bisphosphonates, via the in vivo formation of P-C-P derivatives of ATP. The synthesis and biological evaluation of a large number of nitrogen-containing bisphosphonates in the 1980s and 1990s led to the key discovery that the antiresorptive effects of these more complex analogs on osteoclasts result mostly from their potency as inhibitors of the enzyme farnesyl diphosphate synthase (FDPS/FPPS). This key branch-point enzyme in the mevalonate pathway of cholesterol biosynthesis is important for the generation of isoprenoid lipids that are utilized for the post-translational modification of small GTP-binding proteins essential for osteoclast function. Since then, it has become even more clear that the overall pharmacological effects of individual bisphosphonates on bone depend upon two key properties: the affinity for bone mineral and inhibitory effects on biochemical targets within bone cells, in particular FDPS. Detailed enzyme-ligand crystal structure analysis began in the early 2000s and advances in our understanding of the structure-activity relationships, based on interactions with this target within the mevalonate pathway and related enzymes in osteoclasts and other cells have continued to be the focus of research efforts to this day. In addition, while many members of the bisphosphonate drug class share common properties, now it is more clear that chemical modifications to create variations in these properties may allow customization of BPs for different uses. Thus, as the appreciation for new potential opportunities with this drug class grows, new chemistry to allow ready access to an ever-widening variety of bisphosphonates continues to be developed. Potential new uses of the calcium phosphate binding mechanism of bisphosphonates for the targeting of other drugs to the skeleton, and effects discovered on other cellular targets, even at non-skeletal sites, continue to intrigue scientists in this research field.

Spatiotemporally controlled calcitonin delivery: Long-term and targeted therapy of skeletal diseases

Bone is a connective tissue that support the entire body and protect the internal organs. However, there are great challenges on curing intractable skeletal diseases such as hypercalcemia, osteoporosis and osteoarthritis. To address these issues, calcitonin (CT) therapy is an effective treatment alternative to regulate calcium metabolism and suppress inflammation response, which are closely related to skeletal diseases. Traditional calcitonin formulation requires frequent administration due to the low bioavailability resulting from the short half-life and abundant calcitonin receptors distributed through the whole body. Therefore, long-term and targeted calcitonin delivery systems (LCDS and TCDS) have been widely explored as the popular strategies to overcome the intrinsic limitations of calcitonin and improve the functions of calcium management and inflammation inhibition in recent years. In this review, we first explain the physiological effects of calcitonin on bone remodeling: (i) inhibitory effects on osteoclasts and (ii) facilitated effects on osteoblasts. Then we summarized four strategies for spatiotemporally controlled delivery of calcitonin: micro-/nanomedicine (e.g. inorganic micro-/nanomedicine, polymeric micro-/nanomedicine and supramolecular assemblies), hydrogels (especially thermosensitive hydrogels), prodrug (PEGylation and targeting design) and hybrid biomaterials. Subsequently, we discussed the application of LCDS and TCDS in treating hypercalcemia, osteoporosis, and arthritis. Understanding and analyzing these advanced calcitonin delivery applications are essential for future development of calcitonin therapies toward skeletal diseases with superior efficacy in clinic.

Understanding the Protective Effect of Phytate in Bone Decalcification Related-Diseases

Myo-inositol hexaphosphate (phytate; IP6) is a natural compound that is abundant in cereals, legumes, and nuts, and it can bind to crystal surfaces and disturb crystal development, acting as crystallization inhibitor. The adsorption of such inhibitors to crystal faces can also inhibit crystal dissolution. The binding of phytate to metal cofactors suggests that it could be used for treatment of osteoporosis. Our in-vitro study showed that phytate inhibits dissolution of hydroxyapatite (HAP). The effect of phytate was similar to that of alendronate and greater than that of etidronate. This led us to perform a cross-sectional study to investigate the impact of consumption of IP6 on bone mineral density (BMD) in post-menopausal women. Our data indicate that BMD and t-score of lumbar spine increased with increasing phytate consumption, and a phytate consumption higher than 307 mg/day was associated with a normal BMD (t-score > −1). These data suggest that phytate may have a protective effect in bone decalcification by adsorbing on the surfaces of HAP, and a daily consumption of phytate-rich foods (at least one serving/day of legumes or nuts) may help to prevent or minimize bone-loss disorders, such as osteoporosis. However, further studies are needed to gain a better understanding about the mechanism of inhibition of phytate in bone-related diseases (see graphical abstract).

Bisphosphonates in Dentistry – State of the Art

Bisphosphonates remain the most used and most effective drugs for the treatment of systemic bone diseases followed by bone resorption. Although their side effects in a form of alveolar bone osteonecrosis have been reported, bisphosphonates have a potential of being used in the treatment of the most common oral diseases followed by alveolar bone resorption such as peri-implantitis, periapical lesions, and periodontitis. The aim of this article was to review the most recent research regarding the use of bisphosphonates in the field of dentistry. The results of studies indicate that bisphosphonate use in the treatment of peri-implantitis, periapical lesions, and periodontitis can reduce alveolar bone resorption and contribute to bone preservation. However, the most beneficial way of their application in the treatment of these oral diseases remain to be determined.

Inhibition of the mevalonate pathway improves myocardial fibrosis

The mevalonate (MVA) pathway serves an important role in ventricular remodeling. Targeting the MVA pathway has protective effects against myocardial fibrosis. The present study aimed to investigate the mechanism behind these effects. Primary cultured cardiac fibroblasts from C57BL/6 mice were treated in vitro in 5 groups: i) negative control; ii) angiotensin II (Ang II) model (1x10^-5 mol/l); iii) Ang II + rosuvastatin (ROS); iv) Ang II + alendronate (ALE); and v) Ang II + fasudil (FAS). Collagen and crystal violet staining were used to assess morphological changes in cardiac fibroblasts. Reverse transcription quantitative PCR and western blotting were used to analyze the expression of key signaling molecules involved in the MVA pathway. Collagen staining in the ALE, FAS, and ROS groups was weak compared with the Ang II group, while the rate of cell proliferation in the ROS, ALE, and FAS groups was slower compared with that in the Ang II group. In addition, the expression of key signaling molecules in the MVA pathway, including transforming growth factor-β1 (TGF-β1), heat shock protein 47 (HSP47), collagen type I α1 (COL1A1), vascular endothelial growth factor 2 (VEGF2) and fibroblast growth factor 2 (FGF2), was decreased in the FAS and ROS groups compared with the Ang II model. Compared with the Ang II group, 3-Hydroxy-3-Methylglutaryl-CoA reductase (HMGCR) gene expression was significantly lowered in the drug intervention groups, whereas farnesyl pyrophosphate synthase (FDPS) expression was downregulated in the ALE group, but elevated in the FAS and ROS groups. Compared with that in the Ang II group, ras homolog family member A (RhoA) expression was downregulated in the FAS and ROS groups, whilst mevalonate kinase expression was reduced in the ROS group. Protein expression of TGF-β1, COL1A1 and HSP47 were decreased following intervention with each of the three drugs compared with the Ang II group. Overall, rosuvastatin, aledronate and fasudil decreased the proliferation of myocardial fibroblasts and inhibited collagen synthesis. Rosuvastatin had the strongest protective effects against myocardial fibrosis compared with the other drugs tested, suggesting this to be a potential agent for the clinical treatment of cardiovascular disease.

The biology of vascular calcification

Vascular calcification (VC), characterized by different mineral deposits (i.e., carbonate apatite, whitlockite and hydroxyapatite) accumulating in blood vessels and valves, represents a relevant pathological process for the aging population and a life-threatening complication in acquired and in genetic diseases. Similarly to bone remodeling, VC is an actively regulated process in which many cells and molecules play a pivotal role. This review aims at: (i) describing the role of resident and circulating cells, of the extracellular environment and of positive and negative factors in driving the mineralization process; (ii) detailing the types of VC (i.e., intimal, medial and cardiac valve calcification); (iii) analyzing rare genetic diseases underlining the importance of altered pyrophosphate-dependent regulatory mechanisms; (iv) providing therapeutic options and perspectives.

Osteoblastic and anti-osteoclastic activities of strontium-substituted silicocarnotite ceramics: In vitro and in vivo studies

Osteoporosis bone defect is a refractory orthopaedic disease which characterized by impaired bone quality and bone regeneration capacity. Current therapies, including antiosteoporosis drugs and artificial bone grafts, are not always satisfactory. Herein, a strontium-substituted calcium phosphate silicate bioactive ceramic (Sr-CPS) was fabricated. In the present study, the extracts of Sr-CPS were prepared for in vitro study and Sr-CPS scaffolds were used for in vivo study. The cytocompatibility, osteogenic and osteoclastogenic properties of Sr-CPS extracts were characterized in comparison to CPS. Molecular mechanisms were also evaluated by Western blot. Sr-CPS extracts were found to promote osteogenesis by upregulating Wnt/β-catenin signal pathways and inhibit osteoclastogenesis through downregulating NF-κB signal pathway. In vivo, micro-CT, histological and histomorphometric observation were conducted after 8 weeks of implantation to evaluate the bone formation using calvarial defects model in ovariectomized rats. Compared with CPS, Sr-CPS significantly promoted critical sized ovariectomy (OVX) calvarial defects healing. Among all the samples, Sr-10 showed the best performance due to a perfect match of bone formation and scaffold degradation rates. Overall, the present study demonstrated that Sr-CPS ceramic can dually modulate both bone formation and resorption, which might be a promising candidate for the reconstruction of osteoporotic bone defect.

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Easy-to-perform and cost-effective fabrication of Sr-CPS scaffold.

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Dual modulation of bone formation and resorption.

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Outstanding performances in the osteoporotic bone defect healing process.

Natural protein bioinspired materials for regeneration of hard tissues

This review describes the protein bioinspired materials for the repair of hard tissues such as enamel, dentin and bone.