Cellular mechanisms of bone remodeling

Restoration of hydroxyapatite particle thickness and crystalline orientation does not lead to recovery of tissue-scale mechanical properties in regenerating rat calvarial bone defects

Various cellular activities regulate bone healing, causing structural changes and evolving mechanical characteristics during the regeneration process. This pilot study aimed to correlate the time- and space-resolved mechanical behavior of regenerating and related biological processes. While the mechanical properties of bone are known to be based on a nanostructure organization, this study intends to highlight the evolution of the strain distribution induced by the reconstruction process, which is mainly driven by the mineral part (i.e., hydroxyapatite) of the bone architecture. Multiscale mechanical (tensile and nanoindentation tests) and biological (X-ray microtomography measurements and histological observations) characterization methods were applied to 3 mm rat cranial defects, one of the most reproducible animal models used to assess bone regeneration, filled with bone grafts, the gold standard for bone repair. The size and crystallographic orientation of the hydroxyapatite particles as well as their lattice (elastic) strain distribution under tensile loading were investigated through in situ synchrotron wide-angle and small-angle X-ray scattering measurements at various healing stages. Analyses were completed to quantify the elastic properties at the tissue-scale via nanoindentation measurements. The resulting mappings of lattice strain, mean particle thickness and crystallographic orientations revealed how tissue evolves during bone repair. At the early stages of the regeneration process, the microstructural changes consisted of a restored hydroxyapatite platelet shape and crystallographic orientation. At later stages, the hydroxyapatite crystallographic orientation reached that of native bone, and the mechanical function of the tissue in the defect zone was restored at the mineral particle scale. Nevertheless, even for the longest regeneration duration (20 weeks), mechanical properties at the tissue-scale remained ineffective, highlighting the importance of multiscale investigations to address this type of issue.

Effect of microgravity on bone Tissue: Mechanisms of osteodegeneration and advanced treatment modalities

Preeminent human existence in space raises concerns about bone health due to the effect of microgravity on bone tissue degeneration. Space experiments pose logistical challenges, but ground-based research using microgravity simulation provides information about bone loss mechanisms. This review compiles and evaluates data from astronaut, animal, and cellular experiments, emphasizing microgravity-induced skeletal deconditioning. These findings contribute to creating treatment approaches for preventing bone loss risks in space and potentially on Earth. Astronauts experience notable bone loss, up to 1 %-2 % per month in a gravity-less environment, predominantly influencing weight-bearing bones. These necessitate finding efficient treatment approaches for preventing bone loss risks in space and potentially on Earth. There is a significant need to investigate microgravity's impact on various bone compartments and skeletal recovery processes. The current review explores the stages of bone remodeling and the fundamental causes of bone loss in microgravity, including effects on osteoblasts, osteocytes, osteoclasts, hematopoietic stem cells, and bone marrow stromal cells, as well as the impact on calcium levels. The article also explores various treatment options, including general management, recent therapies, supportive therapies, and emerging therapies such as BP-NELL-PEG, melatonin, calcitonin, and molecular therapies, highlighting their therapeutic potential against microgravity-induced bone loss.

The relationship between primate distal fibula trabecular architecture and arboreality, phylogeny and size

The fibula, despite being traditionally overlooked compared to the femur and the tibia, has recently received attention in primate functional morphology due to its correlation with the degree of arboreality (DOA). Highlighting further fibular features that are associated with arboreal habits would be key to improving palaeobiological inferences in fossil specimens. Here we present the first investigation on the trabecular bone structure of the primate fibula, focusing on the distal epiphysis, across a vast array of species. We collected μCT data on the distal fibula for 21 species of primates, with representatives from most of the orders, and we employed a recently developed approach implemented in the R package 'indianaBones' to isolate the entire trabecular bone underlying an epiphysis or articular facet. After extracting both traditional trabecular parameters and novel topological indices, we tested for the posited relationship between trabecular bone and DOA. To disentangle this effect from others related to body size and phylogenetic relationship, we included a body mass proxy as covariate and employed phylogenetic comparative methods. We ran univariate/multivariate and exploratory/inferential statistical analyses. The trabecular structure of the fibular distal epiphysis in primates does not appear to be associated with the DOA. Instead, it is strongly affected by body mass and phylogenetic relationships. Although we identified some minor trends related to human bipedalism, our findings overall discourage, at this stage, the study of distal fibula trabecular bone to infer arboreal behaviors in extinct primates. We further found that body size distribution is strongly related to phylogeny, an issue preventing us from unravelling the influence of the two factors and that we believe can potentially affect future comparative analyses of primates. Overall, our results add to previous evidence of how trabecular traits show variable correlation with locomotor aspects, size and phylogenetic history across the primate skeleton, thus outlining a complex scenario in which a network of interconnected factors affects the morphological evolution of primates. This work may represent a starting point for future studies, for example, focusing on the effect of human bipedalism on distal fibula trabecular bone, or aiming to better understand the effects of body size and phylogenetic history on primate morphological evolution.

The qualitative analysis of trabecular architecture of the proximal femur based on the P45 sectional plastination technique

The primary weight-bearing structure of the proximal femur, trabecular bone, has a complex three-dimensional architecture that was previously difficult to comprehensively display. This study examined the spatial architecture of trabecular struts in the coronal, sagittal, and horizontal sections of the proximal femur using 21 cases prepared with P45 sectional plasticization. The primary compressive strut (PCS) exhibited a "mushroom-like" shape with upper and lower parts. The lower part extended from the medial inferior cortical bone of the femoral neck to the central region of the femoral head, while the upper part radiated from the epiphyseal line to the subchondral cortical bone of the femoral head. The secondary compressive strut (SCS), originated below the distal end of the PCS, ran diagonally upward, and intersected with the secondary tensile strut (STS) within the greater trochanter. The primary tensile strut (PTS) comprised anterior (aPTS) and posterior (pPTS) components originating from the anterior- and posterior-superior cortical bone of the femoral neck. These converged, entered the femoral head, intersected with the PCS beneath the epiphyseal line, forming a dense trabecular center, and terminated at the subchondral cortical bone below the fovea of the femoral head. The secondary tensile strut (STS) originated from the cortical bone around the lower edge of the greater trochanter, converging upwards and medially to terminate at the superior cortical bone of the femoral neck. The trabecular system of the proximal femur consists of two subsystems: one between the femoral head and neck, and another between the femoral neck and shaft. The head-neck system comprises intersecting PCS, aPTS, and pPTS, facilitating stress transmission. The neck-shaft system features intersecting STS and SCS, enabling stress transmission between these regions. These independent systems are separated by Ward's triangle. The findings of this study offer anatomical guidance for the improvement of internal fixation methods, orthopedic implants, and the design of surgical robots.

The roles of natural killer cells in bone and arthritic disease: a narrative review

The skeletal system is responsible for the body's support and motor functions, and can be pathologically affected by factors, such as metabolism, autoimmune inflammation, tumors, and infections. Regarding tissue localization and biological function, the immune system is deeply involved in the physiological and pathological processes of the skeletal system. As a regulator and effector cell of the innate immune system, natural killer (NK) cells can exert cytotoxic effects through cell contact and immunomodulatory effects through cytokine secretion. In the past 30 years, many advances have been made regarding the role of NK cells and their derived cytokines on bone and joints. In this review, the role of NK cells in the physiological activities of bone remodeling is summarized first, focusing on osteoclast differentiation and function. Subsequently, the roles of NK cells in osteoarthritis, bone tumors, and bone diseases caused by microbial infections are described, meanwhile, some conflicting research results are discussed. By reviewing the state-of-the-art progress of NK cells in the above-mentioned bone physiological and pathological processes, it is helpful to clarify the blind spots of current research and provide some references for the integrated evaluation of immune factors in the study of skeletal system diseases.

Targeted disruption of PRC1.1 complex enhances bone remodeling

Polycomb repressive complexes (PRCs) are pivotal epigenetic regulators that preserve cell identity by restricting transcription responses to sub-threshold extracellular signals. Their roles in osteoblast function and bone formation remain unclear. Here in aging osteoblasts, we found marked activation of PRC1.1 complex, with KDM2B acting as a chromatin-binding factor and BCOR and PCGF1 enabling histone H2A monoubiquitylation (H2AK119ub1). Osteoblast-specific Kdm2b inactivation significantly enhances bone remodeling under steady-state conditions and in scenarios of bone loss. This enhancement is attributed to H2AK119ub1 downregulation and subsequent Wnt signaling derepression. Furthermore, we developed a small molecule termed iBP, that specifically inhibits the interaction between BCOR and PCGF1, thereby suppressing PRC1.1 activity. Notably, iBP administration promotes bone formation in mouse models of bone loss. Therefore, our findings identify PRC1.1 as a critical epigenetic brake on bone formation and demonstrate that therapeutic targeting of this complex enhances Wnt pathway activation, offering a promising strategy against skeletal deterioration.

Role of Masticatory Force in Modulating Jawbone Immunity and Bone Homeostasis: A Review

Mastication exerts a significant influence on both the structural and immunological environment of the jawbone. The mechanical stress generated during chewing initiates bone remodeling through the coordinated activities of osteoclasts and osteoblasts, with these processes being modulated by immune cell responses. This review summarizes the interaction between masticatory forces and jawbone immunity, focusing on key mechanisms such as mechanotransduction in osteocytes, macrophage polarization, and the activation of T cells. The review also delves into the role of the receptor activator of nuclear factor κ-B ligand (RANKL), receptor activator of nuclear factor κ-B (RANK), and osteoprotegerin (OPG) signaling pathway, highlighting its critical function in bone resorption and immune regulation. Additionally, the review summarizes how masticatory forces modulate the immune response through changes in immune cells, particularly focusing on cytokines, and the involvement of hormonal and molecular pathways. These findings provide valuable insights into the complex interplay between mechanical forces and immune cells, with implications for bone health.

Insights into the role of histone lysine demethylases in bone homeostasis and skeletal diseases: A review

Histone lysine demethylases (KDMs), as important epigenetic regulators, are involved in various biological processes such as energy metabolism, apoptosis, and autophagy. Recent research shows that KDMs activate or silence downstream target genes by removing lysine residues from histone tails, and participate in the regulation of bone marrow mesenchymal stem cells (BM-MSCs), osteoblasts (OB), osteoclasts (OC), chondrocytes and other skeletal cell development, differentiation and formation. Moreover, several members of the KDM family affect the occurrence and development of bone diseases such as osteoporosis (OP), osteoarthritis (OA), osteosarcoma (OS), by regulating target genes. Specific regulation mechanisms of KDMs suggest new strategies for bone disease treatment and prevention. Despite the unique function and importance of KDMs in the skeletal system, previous studies have never systematically summarized their specific role, molecular mechanism, and clinical treatment in bone physiology and pathology. Therefore, this review summarises the expression pattern, intracellular signal transduction, and mechanism of action of the KDM family in several bone physiological and pathological conditions, aiming to highlight the important role of KDMs in bone diseases and provide a reference for the future treatment of bone diseases.

Effect of eccentric-based resistance exercise on bone (re)modelling markers across the menstrual cycle and oral contraceptive cycle

PURPOSE

To investigate the acute effects of eccentric-based resistance exercise and sex-hormone fluctuations on P1NP and β-CTX-1 concentrations in premenopausal females.

METHODS

Nine eumenorrheic females and ten oral contraceptive (OC) users performed eccentric-based resistance exercise, consisted of 10 × 10 repetitions of parallel back squats with a 4-s eccentric phase, in the early-follicular (EFP), late-follicular (LFP) and mid-luteal (MLP) phases of the menstrual cycle (MC) or in the withdrawal (WP) and active pill-taking (APP) phases of the OC cycle.

RESULTS

17β-oestradiol (pg·ml-1) was lower in EFP (36.63 ± 29.93) compared to LFP (224.81 ± 233.81; p ≤ 0.001) and MLP (161.45 ± 110.08; p < 0.001) and higher in WP (24.857 ± 29.428) compared to APP (12.72 ± 13.36; p = 0.004). Progesterone (ng·ml-1) was higher in MLP (8.30 ± 5.23) compared to EFP (0.33 ± 0.33; p < 0.001) and LFP (0.21 ± 0.18; p < 0.001), no significant differences were observed between the WP and APP. In eumenorrheic females, β-CTX-1 (ng·ml-1) was lower in MLP (0.395 ± 0.126) compared to LFP (0.472 ± 0.137; p = 0.044). Comparing MC vs OC phases, eumenorrheic females had higher P1NP levels (ng·ml-1) compared to OC users: EFP (62.54 ± 13.13) vs APP (50.69 ± 8.91; p = 0.034), LFP (67.32 ± 18.96) vs WP (52.16 ± 10.72; p = 0.047), LFP vs APP (p = 0.025), MLP (67.51 ± 19.34; p = 0.049) vs WP, MLPvsAPP (p = 0.027). Exercise time effect showed lower β-CTX-1 concentrations 2 h post-exercise (MC: 0.376 ± 0.114, p < 0.001; OC: 0.340 ± 0.156, p = 0.030) compared to pre-exercise (MC: 0.485 ± 0.137; OC: 0.428 ± 0.188) in all participants.

CONCLUSIONS

β-CTX-1 concentrations were lower in the mid-luteal phase, emphasising the importance of standardizing bone marker measurements to a specific MC phase. OC users exhibited reduced P1NP levels, underscoring the need to investigate synthetic and endogenous hormones' impact on long-term bone structure and strength. Trial registration The study was registered at Clinicaltrials.gov NCT04458662 on 2 July 2020.

Fibrosis factor CTGF facilitates VCAM‑1‑dependent monocyte adhesion to osteoarthritis synovial fibroblasts via the FAK and JNK pathways

Osteoarthritis (OA) is a long‑term, degenerative joint disease that presents significant clinical challenges and imposes considerable financial burdens. Fibrosis is closely intertwined with the pathogenesis of various degenerative diseases, including OA. Using data from the GDS5401 dataset, the present study determined that expression levels of the fibrosis factor connective tissue growth factor (CTGF) were significantly higher in OA patients than in normal individuals. The present study also identified CTGF elevated expression levels in both OA patients compared with healthy controls and in rats with anterior cruciate ligament transection‑induced OA versus controls. Stimulating OA synovial fibroblasts (OASFs) with CTGF was shown to promote vascular cell adhesion molecule‑1 (VCAM‑1) production, thereby facilitating monocyte adhesion to OASFs. Analysis of a large dataset revealed that monocytes are the only mononuclear cells with significantly elevated levels in OA patients. It also appeared that CTGF‑induced VCAM‑1 production and monocyte adhesion were mediated via the focal adhesion kinase and JNK pathways. These findings suggest that CTGF contributes to OA progression by enhancing monocyte adhesion to the synovial membrane.

Self-assembled water soluble and bone-targeting phosphorylated quercetin ameliorates postmenopausal osteoporosis in ovariectomy mice

Natural compounds have shown promising application prospects in preventing or treating various diseases, including osteoporosis on account of their abundant sources, low price, multi-targeting and multiple biological effects. As a bioactive natural product, quercetin (Que) has previously demonstrated to ameliorate osteoporosis (OP), however, its poor bioavailability resulting from low water solubility, poor stability and lack of bone-targeting largely restricted its efficacy and clinical applications. Inspired by the bone-targeting capability of phosphate compounds, we reported a one-step procedure for synthesis of phosphorylated Que (p-Que) by direct phosphorylating phenol groups of Que for the first time. The phosphate groups on p-Que could not only improve the water dispersibility of Que, but also endow p-Que desirable bioavailability and bone-targeting feature. The results from biological assays suggested that p-Que could inhibit osteoclastogenesis and bone resorption and alleviate trabeculae loss in osteoporotic mice. In conclusion, this work demonstrated that phosphorylation strategy can effectively solve low water solubility, lack of bone-targeting capability and poor bioavailability of natural compounds, providing a novel and efficient approach for development of OP nanomedicines.

Quercetins efficacy on bone and inflammatory markers, body composition, and physical function in postmenopausal women

INTRODUCTION

This study aimed to investigate the effects of quercetin (a plant-based flavonoid) supplementation over 90 days on prominent bone turnover markers (BTMs), inflammatory markers, bone mineral density (BMD), body composition, and physical function in postmenopausal women.

MATERIALS AND METHODS

Thirty-three healthy postmenopausal women were recruited to participate in a double-blind, placebo-controlled investigation. Participants were randomized into one of two supplement groups: (1) 500 mg of quercetin (QUE) once daily or (2) 500 mg of methylcellulose (placebo; PLB) once daily. Pre- and post-testing visits included assessments of BTMs (i.e., osteocalcin [OC], procollagen type I N-terminal propeptide [PINP], and type I collagen cross-linked C-terminal telopeptide [CTX]), inflammatory markers (i.e., interleukin [IL]-6, tumor necrosis factor-alpha [TNF-α], and C-reactive protein [CRP]), BMD measurements, body composition measurements, and physical function including timed up and go and handgrip strength.

RESULTS

The QUE group increased OC (p = 0.016; d = 0.89), PINP (p = 0.030; d = 0.64), and CTX (p = 0.023; d = 0.91) levels and decreased IL-6 (p = 0.045; d = 0.73) and TNF-α (p = 0.021; d = 0.90) levels compared to PLB. CRP (p = 0.448; d = 0.34), body composition (p > 0.05), and physical function (p > 0.05) remained unchanged.

CONCLUSION

The results suggest that QUE may better assist in controlling a normal bone turnover cycle by mediating bone formation and decreasing pro-inflammatory cytokines. However, although within the accepted range, there was an increase in the bone resorption marker and therefore, it is unclear if QUE will protect against future bone loss. Nonetheless, additional research is necessary to evaluate the bone-conserving properties of QUE among postmenopausal women.

CLINICAL TRAIL REGISTRATION

The ClinicalTrials.gov ID number: NCT05371340.

Bone Remodeling in Children with Acute Lymphoblastic Leukemia: A Two-Year Prospective Longitudinal Study

Childhood leukemia survivors are at risk of long-term complications. Data on bone remodeling in childhood acute lymphoblastic leukemia (ALL) are limited. This 2-year prospective longitudinal study investigated bone remodeling and bone turnover markers at diagnosis, during treatment, and until stopping treatment, in ALL patients < 18 years, to clarify the influence of leukemia itself and/or chemotherapy on bone.

METHODS

A total of 22 ALL children (12 males, age 5.5 ± 3.6 years) underwent blood sampling at the 5 time point (T0-T4). Osteoprotegerin (OPG), receptor-activator-NF-B-ligand (RANKL), osteocalcin (OC), C-terminal-telopeptide-type-I-collagen (CTX), bone-alkaline-phosphatase (bALP), tartrate-resistant acid-phosphatase-5b (TRACP5b), procollagen-type-I-N-terminal-propeptide (P1NP), Dickkopf-1 (DKK-1), and sclerostin were assessed. Data from patients at T0 were compared to a control group of healthy children. We used the principal component analysis (PCA) for statistics.

RESULTS

Levels of CTX, OC, P1NP, and bALP resulted lower in ALL children than controls (p = 0.009 for CTX and p < 0.001 for the others), also DKK1 and sclerostin (p < 0.0001 and p = 0.023). RANKL ed OPG were higher in patients. During T0-T4, CTX, OC, P1NP, TRACP5b, and bALP showed a significant increase, in particular at T0-T1 (end-of-induction). Less evident changes were detected onwards.

CONCLUSIONS

The onset of leukemia has been revealed as a key point in determining a slowing of bone remodeling in ALL children.

Establishing a simple protocol to induce the osteogenic differentiation of MC3T3-E1 cells in 2D and its transfer to 3D spheroid cultures

The murine cell line MC3T3-E1 is used in many in vitro studies in bone-related research, but different protocols to induce its osteogenic differentiation have been reported. The aim of this study was to identify the best mixture of osteogenic supplements to induce osteogenic differentiation of MC3T3-E1 subclone 4 cells in a two-dimensional cell culture setup. As spheroids as three-dimensional cell aggregates are of increasing importance, we also present a simple method to generate osteogenic differ.entiated spheroids on this basis. Three different mixtures of osteogenic supplements were used to induce osteogenic differentiation for up to 28 days. Osteogenic differentiation was monitored by alizarin red and von Kossa staining, energy dispersive X-ray (EDX) analysis, and real-time quantitative PCR analysis of osteogenic marker genes. Spheroids were generated from osteogenic differentiated cells by liquid overlay technique. The use of 5 mM β-glycerophosphate, 10 nM dexamethasone, and 50 µg/mL ascorbic acid was able to induce osteogenic differentiation of MC3T3-E1 cells within 14 days, as shown by strong positive signals in both staining methods. Scanning electron microscopy revealed extracellular secretions on the membranes of differentiated cells with a significantly increased calcium content of 16.4 ± 2.4% and a phosphorus content of 10.1 ± 1.1%, as shown by energy dispersive X-ray analysis. Differentiated MC3T3-E1 cells could be detached by incubation in AccuMax for 10 min and spheroids were generated from this cell suspension on day 14. Significant upregulation of the osteogenic markers Sp7, osteocalcin, and bone sialoprotein was detected by real-time quantitative PCR analysis of these spheroids. In addition to other reports in the literature describing osteogenic differentiation of spheroids, we were able to show that it is also possible to generate spheroids from osteogenically differentiated two-dimensional cell cultures, which are easier to handle. Thus, there are indeed several ways to generate osteogenic differentiated MC3T3-E1 spheroids.

Unraveling the dynamics of osteoblast differentiation in MC3T3-E1 cells: Transcriptomic insights into matrix mineralization and cell proliferation

Unraveling the intricacies of osteoblast differentiation is crucial for advancing our comprehension of bone biology. This study investigated the complicated molecular events orchestrating osteoblast differentiation in MC3T3-E1 cells, a well-established in vitro culture model. Employing longitudinal RNA-sequencing analysis, we explored transcriptomic changes at the pivotal time points of 0, 1, 4, 7, 10, 14, and 21 days and categorized osteogenic differentiation into proliferation, matrix maturation, and mineralization stages. Notably, we observed a simultaneous increase in matrix mineralization and cell proliferation during the mineralization stage, accompanied by a positive correlation between proliferation-associated genes and those enriched in ossification. Additionally, we identified the presence of proliferating cells over the mineralizing matrix layers. These results could serve as a model for understanding the principles by which bone lining cells are formed on the calcified bone matrix and the mechanism by which new osteoblasts are recruited during the bone remodeling process.

Microfabricated Organ-Specific Models of Tumor Microenvironments

Despite the advances in detection, diagnosis, and treatments, cancer remains a lethal disease, claiming the lives of more than 600,000 people in the United States alone in 2024. To accelerate the development of new therapeutic strategies with improved responses, significant efforts have been made to develop microfabricated in vitro models of tumor microenvironments (TMEs) that address the limitations of animal-based cancer models. These models incorporate several advanced tissue engineering techniques to better reflect the organ- and patient-specific TMEs. Additionally, microfabricated models integrated with next-generation single-cell omics technologies provide unprecedented insights into patient's cellular and molecular heterogeneity and complexity. This review provides an overview of the recent understanding of cancer development and outlines the key TME elements that can be captured in microfabricated models to enhance their physiological relevance. We highlight the recent advances in microfabricated cancer models that reflect the unique characteristics of their organs of origin or sites of dissemination.

AI-Assisted Label-Free Monitoring Bone Mineral Metabolism on Demineralized Bone Paper

Effective drug development for bone-related diseases, such as osteoporosis and metastasis, is hindered by the lack of physiologically relevant in vitro models. Traditional platforms, including standard tissue culture plastic, fail to replicate the structural and functional complexity of the natural bone extracellular matrix. Recently, osteoid-mimicking demineralized bone paper (DBP), which preserves the intrinsic collagen structure of mature bone and exhibits semitransparency, has demonstrated the ability to reproduce in-vivo-relevant osteogenic processes and mineral metabolism. Here, we present a label-free, longitudinal, and quantitative monitoring of mineralized collagen formation by osteoblasts and subsequent osteoclast-driven mineral resorption on DBP using brightfield microscopy. A Segment.ai machine learning algorithm is applied for time-lapse bright-field image analysis, enabling identification of osteoclast resorption areas and automated quantification of large image datasets over a three-week culture period. This work highlights the potential of DBP as a transformative platform for bone-targeting drug screening and osteoporosis research.

Probiotics and nanoparticle-mediated nutrient delivery in the management of transfusion-supported diseases

Bone marrow is vital for hematopoiesis, producing blood cells essential for oxygen transport, immune defense, and clotting. However, disorders like leukemia, lymphoma, aplastic anemia, and myelodysplastic syndromes can severely disrupt its function, leading to life-threatening complications. Traditional treatments, including chemotherapy and stem cell transplants, have significantly improved patient outcomes but are often associated with severe side effects and limitations, necessitating the exploration of safer, more targeted therapeutic strategies. Nanotechnology has emerged as a promising approach for addressing these challenges, particularly in the delivery of nutraceuticals-bioactive compounds derived from food sources with potential therapeutic benefits. Despite their promise, nutraceuticals often face clinical limitations due to poor bioavailability, instability, and inefficient delivery to target sites. Nanoparticles offer a viable solution by enhancing the stability, absorption, and targeted transport of nutraceuticals to bone marrow while minimizing systemic side effects. This study explores a range of bone marrow disorders, conventional treatment modalities, and the potential of nanoparticles to enhance nutraceutical-based therapies. By improving targeted delivery and therapeutic efficacy, nanoparticles could revolutionize bone marrow disease management, providing patients with more effective and less invasive treatment options. These advancements represent a significant step toward safer and more efficient therapeutic approaches, ultimately improving patient prognosis and overall health.

Evaluation of the systemic effect of bone formation marker released by endodontic calcium silicate-based sealers in local tissues, the bloodstream, and body organs

Calcium silicate-based sealers are bioactive materials that release ions when in contact with body fluids. Therefore, this study aims mapping/trace bone formation markers released by MTA Fillapex, BioRoot RCS, and experimental tricalcium silicate-based sealer (CEO) into subcutaneous tissues, bloodstream and body organs. Toward, polyethylene tubes filled with sealers were implanted into connective tissue of Wistar rats. On days 7, 15, 30, and 45 after implantation, blood samples were collected to measure calcium (Ca2+), phosphorus (P), and alkaline phosphatase (ALP) levels. Thereafter, the animals were killed, and the brain, liver, kidneys, and subcutaneous tissue were removed and processed to determine the concentrations of Ca2+ and P by ICP-OES. Similar Ca2+ levels were observed in subcutaneous tissue for all groups, although, at 45 days, it was identified a reduction in Ca2+ serum levels of CEO compared to those two other sealers and an increase in Ca2+ levels in the liver compared to those released by MTA Fillapex. In contrast, no trace of P was detected in any tissue; moreover, plasma P and ALP serum levels of MTA Fillapex were higher at day 30. Our findings showed that Ca2+ were identified in local tissues, bloodstream, and organs from all sealers. The up-regulation of bone marker levels promoted by sealers can modify body homeostasis and induce tissue damage. Besides, MTA Fillapex was associated with a raise of bone marker levels, suggesting a possible systemic effect. The sealer composition can affect not only the local repair process but also the systemic health.

Cyclic stretch Promotes osteogenesis of osteoblasts via ACh/α7nAChR pathway

Mechanical loading could affect bone remodeling, which involves the balance between bone resorption and formation. During bone remodeling, osteoblasts act as the primary sensors of mechanical signals, as well as the effectors to translate these signals into bone remodeling. Furthermore, osteoblasts express the Non-Neuronal Cholinergic System (NNCS), including acetylcholine (ACh) and α7 nicotinic Acetylcholine Receptor (α7nAChR), which regulates cellular function. However, the relationship between ACh/α7nAChR pathway and mechanical tension-induced bone remodeling remains unclear. Herein, we explored the effect of mechanical tension on osteoblasts, and the potential role of ACh/α7nAChR pathway in the tension-induced responses in osteoblasts. Specifically, MC3T3-E1 cells were subjected to a cyclic stretch in vitro using the Flexcell-5000™ Tension System. α7nAChR gene was knocked down with small interfering RNA (siRNA). Osteoblast proliferation, osteogenic function and the expression of the cholinergic system were assessed. According to the results, osteoblasts proliferation, osteogenesis-related factors expression [Runt-related Transcription Factor 2 (Runx2), Collagen Type-Ⅰ (Col1), Osteocalcin (Ocn), and Osteopontin (Opn)], and cholinergic system expression [acetylcholine (ACh), Carnitine Acetyltransferase (Carat), Vesicular Acetylcholine Transporter (Vacht), and α7 nicotinic Acetylcholine Receptor (α7nAChR)], these all increased initially, peaked at 8 h of tension, then declined with increasing tension time. Furthermore, mechanical tension with α7nAChR knocked down significantly decreased the early-stage osteogenesis-related genes and proteins expression of RUNX2 and COL1. In conclusion, mechanical tension exerted a time-dependent effect on osteoblasts proliferation, osteogenesis, and cholinergic system, which all increased initially, peaked at 8 h of tension, then declined with increasing tension duration. Furthermore, the ACh/α7nAChR pathway involved in early-stage osteogenesis induced by mechanical tension.

Effects of combined protein and exercise interventions on bone health in middle-aged and older adults - A systematic literature review and meta-analysis of randomized controlled trials

PURPOSE

Osteoporosis has become a global public health concern making prevention and treatment essential to reduce severe consequences for individuals and health systems. This systematic review with meta-analysis aimed to determine the effects of combined protein and exercise interventions compared to (a) exercise alone and (b) protein alone on bone mineral content (BMC) or density (BMD) in middle-aged and older adults.

METHODS

We systematically searched Medline, CINAHL, CENTRAL, Web of Science, and SPORTDiscus until 24th January 2023. Pairwise random-effects meta-analyses were performed to calculate weighted mean differences (WMD) with 95% confidence intervals (95% CI). We evaluated risk of bias (Cochrane RoB2) and certainty of evidence (CoE; GRADE). If pooling was not possible, the results were summarized descriptively.

RESULTS

For the comparison of combined protein supplementation and exercise vs. exercise alone, no meta-analysis for BMD (2 RCTs) was possible. For BMC, little to no intervention effect was found (WMD 0.03 kg; 95% CI - 0.00 to 0.05; 4 RCTs; IG = 97/CG = 98; I2 = 58.4%). In a sensitivity analysis, restricted to combined milk-protein supplementation and exercise, the result remained similar (0.01 kg; 95% CI - 0.01 to 0.03; 4 RCTs; IG = 71/CG = 71; I2 = 0.0%; low CoE). For the comparison of combined protein and exercise interventions vs. protein alone, no RCT on BMC was identified; the results on total or regional BMD (2 RCTs) were inconclusive.

CONCLUSION

Based on our findings, no robust conclusions can be drawn on whether combining protein and exercise interventions is more beneficial for bone health than one component alone. Sufficiently powered studies with longer duration are required to clarify these questions (CRD42022334026).

Alternating electrical fields to stimulate osteogenic cells and biomimetic calcium phosphate-coated titanium substrates-A combinatorial approach to bone regeneration

Biophysical stimuli such as alternating electrical fields can mimic endogenous electrical potentials and currents in natural bone. This can help to improve the healing and reconstruction of bone tissue. However, little is known about the combined influence of biomaterials and alternating electric fields on bone cells. Therefore, this study aimed to investigate the impact of both, biomaterials and alternating electric fields, on osteoblast as well as osteoclast differentiation. Initially, either RAW 264.7 or MC3T3-E1 cells were seeded on Ti6Al4V substrates as a load-bearing implant material, modified with biomimetic calcium phosphate (BCP), or uncoated as a reference. The cells were stimulated towards osteoclastic and osteoblastic differentiation via respective growth factors. The effects of BCP substrate modification on cell differentiation were examined after 7 days for RAW 264.7 and after 14 days for MC3T3-E1 cells. In a further series of tests, either RAW 264.7 or MC3T3-E1 cells were seeded on BCP-modified Ti6Al4V substrates, stimulated towards differentiation using growth factors, and further electrically stimulated via alternating electric fields of different voltages and frequencies. In parallel to the first test series RAW 264.7 and MC3T3-E1 cells were stimulated for 7 and 14 days, respectively. Cell morphology was examined via scanning electron microscopy. Cell viabilities were assessed via WST-8 assay. Electrically stimulated MC3T3-E1 cell orientation was evaluated based on fluorescence microscopy images. Marker genes were examined via qPCR. While BCP increased osteoclast-specific gene expression, it had the opposite effect on osteoblast-related genes compared to respective cells seeded on uncoated Ti6Al4V substrates. ES with different parameters showed a broad cellular response due to electrocoupling. While cell viability assessments and gene expression analyses showed clear differences between ES samples and unstimulated controls, only minor cell morphology and orientation differences were observed. Furthermore, there was no clear trend towards a dominant influence of either voltage or frequency as control parameters. Further studies were initiated to investigate the underlying intracellular mechanisms targeted by ES. This work provides an introduction to the targeted control of cellular processes using defined electric fields. The optimization of voltage and frequency could provide therapeutic windows to control specific cellular functions and potentially improve bone regeneration and remodeling processes.

Sponge Morphology of Osteosarcoma Finds Origin in Synergy Between Bone Synthesis and Tumor Growth

Osteosarcoma is medically defined as a bone-forming tumor with associated bone-degrading activity. There is a lack of knowledge about the network that generates the overproduction of bone. We studied the early stage of osteosarcoma development with mice enduring a periosteum injection of osteosarcoma cells at the proximal third of the tibia. On day 7 (D7), tumor cells activate the over-synthesis of bone-like material inside the medulla. This overproduction of bone is quickly (D13) followed by degradation. Samples were characterized by microfocus small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), optical and electron microscopies, and micro-indentation. This intramedullary apatite-collagen composite synthesis highlights an unknown network of bone synthesis stimulation by extramedullary osteosarcoma cells. This synthesis activation mechanism, coupled with the well-known bone induced osteosarcoma growth activation, produces a rare synergy that may enlighten the final osteosarcoma morphology. With this aim, a 3D cellular automaton was developed that only included two rules. Simulations can accurately reproduce the bi-continuous sponge macroscopic structure that was analyzed from mice tumor micro-tomography. This unknown tumor activation pathway of bone synthesis, combined with the known bone activation of tumor growth, generates a positive feedback synergy explaining the unusual sponge-like morphology of this bone cancer. From a biomaterials point of view, how nature controls self-assembly processes remains an open question. Here, we show how the synergy between two biological growth processes is responsible for the complex morphology of a bone tumor. This highlights how hierarchical morphologies, accurately defined from the nanometer to the centimeter scale, can be controlled by positive feedback between the self-assembly of a scaffold and the deposition of solid material.

Strength training for osteoporosis prevention during early menopause (STOP-EM): a pilot study protocol for a single centre randomised waitlisted control trial in Canada

INTRODUCTION

Women lose up to 10% of their bone mass around menopause and the decade following. There is a need for proactive approaches to preserve bone mass and quality around menopause. Existing work has found that high-intensity resistance and impact training (HiRIT) can improve bone and muscle measures in late postmenopausal women. However, this has not been investigated in perimenopausal and early postmenopausal women who are in the midst of the menopausal transition.

METHODS AND ANALYSIS

This study is a 9-month randomised controlled feasibility trial evaluating a HiRIT programme in perimenopausal and early postmenopausal women. The primary objective of this study is to determine the feasibility of HiRIT in 40 perimenopausal and early postmenopausal women (45-60 years). Participants will be randomised 1:1 into a supervised HiRIT exercise intervention and waitlisted control. The primary outcomes are recruitment, retention and adherence to the exercise intervention. Secondary outcomes include bone (bone mineral density, microarchitecture and strength), muscle (mass, strength and power), physical function (balance and aerobic fitness) and quality of life measures. Feasibility will be assessed based on a priori criterion for success and secondary outcomes will be assessed via multiple linear regressions. The study will be considered feasible if>50% of interested and eligible participants are recruited, if there is>60% adherence to the two times per week, 9-month exercise intervention and if at least 65% of the sample complete the final study visit. Feasibility outcomes will be used to inform a larger, future trial aimed at identifying the efficacy of the exercise intervention for improving various health outcomes, including bone density and muscle mass. Secondary exploratory outcomes will provide insight into the effect of exercise on muscle and bone in perimenopausal and early postmenopausal women.

ETHICS AND DISSEMINATION

This study has been approved by the Conjoint Health Research Ethics Board of the University of Calgary REB22-1632. The results of this study will be disseminated at national and international conferences and published in academic journals.

TRAIL REGISTRATION NUMBER

ClinicalTrials.gov: NCT05961371. (Protocol V.1.2, 28 September 2023).

Antiosteoporosis and Bone Protective Effect of Phyllanthin Against Glucocorticoid-induced Osteoporosis in Rats via Alteration of HO-1/Nrf2 and RANK/RANKL/OPG Pathway

BACKGROUND

Osteoporosis is a condition where bones weaken due to a loss in density and quality, making them fragile and more susceptible to fractures, even from minor stress or injury. In this experimental study, we scrutinized the antiosteoporosis effect of phyllanthin against glycocorticoid (GIOP) induced osteoporosis in rats.

METHODS

SD rats were used in this study and subcutaneous administration of DEX (3 mg/kg) was used for the induction of osteoporosis and rats were treated with phyllanthin and alendronate for 12 weeks. The body weight, femur mass, length, hormones, nutrients, antioxidant, cytokines and bone parameters were estimated. The mRNA expression of HO-1, Nrf2, RANK, RANKL and OPG were estimated.

RESULTS

Phyllanthin treatment significantly (p < 0.001) improved the body weight, femur mass and femur length. Phyllanthin significantly (p < 0.001) altered the level of hormones estrodiol, PTH; nutrients such as calcium, phosphorus, magnesium; Bone mineral content (BMC) and bone mineral density (BMD); Bone formation marker like ALP, TRAP, osteocalcin, β-CTX, BGP, cathepsin K, DPD; Bone parameters viz., Tb.N, BV/TV, Tb.sp, BS/BV, Tb.Th; Bone structure analysis includes maximum load, energy, stiffness, maximum stress, young's modules; oxidative stress parameters such as TBARS, CAT, GPx, GSH, GR; cytokines such as TNF-α, IL-1β, IL-6, IL-10 and antioxidant marker such as HO-1 and Nrf2. Phyllanthin significantly (P < 0.001) altered the mRNA expression of HO-1, Nrf2, RANK, RANKL and OPG.

CONCLUSION

On the basis of result, we can say that phyllanthin exhibited the antiosteoporosis effect against glucocorticoid-induced osteoporosis in rats via alteration of HO-1/Nrf2 and RANK/RANKL/OPG pathway.

Effect of yoga on balance, falls, and bone metabolism: a systematic review of randomized controlled trials in healthy individuals

This systematic review of 18 RCTs assessed the impact of yoga on balance, fall risk, fear of falling, bone mineral density (BMD), and bone turnover markers in healthy individuals. Yoga significantly improved balance but its effects on BMD were inconclusive. Standardised protocols and longer-term studies are needed.

BACKGROUND

Yoga's effects on interconnected bone health parameters viz balance, falls, fear of falling (FOF), bone mineral density (BMD), and bone turnover markers (BTMs) in healthy individuals are unclear. We critically evaluated randomized controlled trials (RCTs) that compared yoga to no intervention control (NIC) or comparators such as Tai Chi, on these parameters in healthy individuals.

METHODS

We systematically searched multiple scientific data bases using a predefined protocol. We summarized data qualitatively when there was heterogeneity in reporting. A meta-analysis of those studies comparing yoga to NIC was done. Since the included studies used different scales for the same outcomes, we used standardised mean differences (SMDs) to allow pooling. We assessed the risk of bias with the Cochrane RoB2 tool for randomized trials and graded certainty of evidence using the GRADE approach.

RESULTS

Eighteen RCTs with 1408 participants were evaluated. Fifteen explored yoga's effects on balance and/or falls or FOF, and three RCTs, its effect on BMD and BTMs. Yoga types included Hatha, Vinyasa, Ashtanga, Iyengar, Bikram, and specially designed yoga protocols. Twenty-four kinds of balance assessment tools were used in the studies. Study durations varied from 6 weeks to 14 months. Almost all the studies reported positive effects of yoga on balance compared to NIC, and non-inferiority when compared to active interventions such as Tai Chi. Meta-analysis of four RCTs comparing yoga to NIC demonstrated significant improvements in static balance with yoga (SMD = 2.36; 95% CI 1.13-3.58; P = 0.0002, I2 = 93% ⊕ ⊕ ⊝ ⊝). Yoga's effects on falls and FOF were mixed. Two studies showed a positive effect of yoga on bone formation. Yoga was found to have a positive effect on BMD in only one study. Meta-analysis of two RCTs showed no significant effect on BMD for yoga compared to NIC. The studies exhibited substantial heterogeneity in terms of yoga styles, intervention durations, and assessment methods.

CONCLUSION

In healthy adults, low certainty evidence shows that yoga has a beneficial effect on balance. Its effect on BMD remains unclear. Standardised protocols and longer-term research are necessary to facilitate more definitive conclusions on yoga's role in enhancing skeletal health and preventing falls.

Comparative evaluation of allograft particulate bone and cortical bone blocks combined with xenograft bone for labial bone defects in the aesthetic zone: a prospective cohort study

PURPOSE

This study aimed to evaluate the osteogenic performance of allograft particulate bone and cortical bone blocks combined with xenograft under bovine pericardium membranes, for treating different degrees of labial bone defects in the aesthetic zone.

MATERIALS AND METHODS

Twenty-four patients with bone defects were divided into two groups based on defect severity (Terheyden 1/4 and 2/4 groups). The Terheyden 1/4 group received granular bone grafts alone, while the Terheyden 2/4 group received cortical bone blocks combined with granular bone grafts. Cone beam computed tomography scans were taken preoperatively, immediately postoperatively, and six months postoperatively. Primary outcomes included labial bone formation, alveolar bone formation, bone resorption rate, osteogenic efficiency, and complications.

RESULTS

Labial bone thickness in both groups exceeded 2 mm after six months. Labial bone formation at the implant shoulder in the Terheyden 1/4 group was 2.35 ± 2.68 mm, and 2.26 ± 1.66 mm in the Terheyden 2/4 group (p > 0.05). Labila and alveolar bone formation at 2-5 mm below the implant shoulder was significantly greater in the Terheyden 2/4 group (p < 0.05). Alveolar bone resorption and the bone resorption rate at 2-5 mm below the implant shoulder was lower in the Terheyden 2/4 group (p < 0.05). Osteogenic efficiency was 64.43 ± 2.76%, with no significant difference between groups (p > 0.05). No complications were observed.

CONCLUSION

Both treatment approaches achieved satisfactory bone regeneration, but combining cortical bone blocks with granular grafts provided better outcomes for larger defects, with greater bone formation and less resorption. Further research with longer follow-up is required to confirm long-term stability.

TRIAL REGISTRATION

The study was retrospectively registered in the Chinese Clinical Trial Registry ( http://www.chictr.org.cn/ ) with the registration number ChiCTR2300070538 on April 14, 2023.

Cracking the code: Understanding ESWT's role in bone fracture healing

Bone non-union has always been a research hotspot in the field of orthopedics. Non-unions are often accompanied by symptoms such as pain, deformity, and dysfunction, which can significantly affect patients' quality of life and cause related socioeconomic problems. Clinically, there are various treatments available for non-unions, and the main treatment methods are divided into surgical and non-surgical treatments. At present, surgery is the most widely used treatment for bone non-unions and has a high healing rate. However, even after surgery, some patients still face the problem of bone non-union. Furthermore, a small number of patients have surgical contraindications and could not tolerate surgery. Therefore, alternative treatments are needed to improve outcomes for patients with bone fractures. Extracorporeal shock wave therapy (ESWT) is a non-invasive treatment method with similar efficacy and better safety compared with surgery. Nevertheless, the exact mechanism for ESWT to treat patients with bone non-union are still not well understood. This article reviews the mechanisms of ESWT in promoting bone fracture healing by regulating osteoblasts and osteoclasts, providing a theoretical foundation for the clinical application of ESWT. The Translational Potential of this Article: This review provides a comprehensive overview of the mechanisms underlying ESWT on promoting bone fracture healing by regulating osteoblasts and osteoclasts. The information provided in this article can offer a novel non-invasive method for clinicians to treat bone non-union.

Comparison Between Nano-Hydroxyapatite/Beta-Tricalcium Phosphate Composite and Autogenous Bone Graft in Bone Regeneration Applications: Biochemical Mechanisms and Morphological Analysis

It was assumed that only autogenous bone had appropriate osteoconductive and osteoindutive properties for bone regeneration, but this assumption has been challenged. Many studies have shown that synthetic biomaterials must be considered as the best choice for guided bone regeneration. The objective of this work is to compare the performances of nanohydroxyapatite/β-tricalcium phosphate (n-HA/β-TCP) composite and autogenous bone grafting in bone regeneration applications. The composite was characterized by scanning electron microscopy (SEM) and used as an allograft in bone defects formed in adult Wistar rats. The bone defects in the dorsal cranium were grafted with autogenous bone on one side and the n-HA/β-TCP composite on the other. Histomorphometry evaluation via different staining methods (Goldner trichrome, PAS, and Sirius red) and TRAP histochemistry were performed. Immunohistomorphometries of OPN, Cathepsin K, TRAP, acid phosphatase, VEGF, NFκ-β, MMP-2, MMP-9, and TGF-β were carried out. The RT-PCR method was also applied to to RANK-L, Osteocalcine, Alcaline Phosphatase, Osterix, and Runx2. The results showed that for all morphometric evaluations with the different staining methods, histochemistry, and immunohistochemistry, VEGF and NFκ-β were higher in the n-HA/β-TCP composite group than in the autogenous bone graft group. The RT-PCR markers were higher in the autogenous bone group than in the n-HA/β-TCP composite group. The n-HA/β-TCP composite exhibited enhanced cell-matrix interactions in bone remodeling, higher adhesion, proliferation, and differentiation, and increased vascularization. These results suggest that the n-HA/β-TCP composite induces faster bone formation than autogenous bone grafting.

A review of the current status and future prospects of the bone remodeling process: Biological and mathematical perspectives

This review dives into the complex dynamics of bone remodeling, combining biological insights with mathematical perspectives to better understand this fundamental aspect of skeletal health. Bone, being a crucial part of our body, constantly renews itself, and with the growing number of individuals facing bone-related issues, research in this field is vital. In this review, we categorized and classified most common mathematical models used to simulate the mechanical behavior of bone under different loading and health conditions, shedding light on the evolving landscape of bone biology. While current models have effectively captured the essence of healthy bone remodeling, the ever-expanding knowledge in bone biology suggests an update in mathematical methods. Knowing the role of the skeleton in whole-body physiology, and looking at the recent discoveries about activities of bone cells emphasize the urgency of refining our mathematical descriptions of the bone remodeling process. The underexplored impact of bone diseases like osteoporosis, Paget's disease, or breast cancer on bone remodeling also points to the need for intensified research into diverse disease types and their unique effects on bone health. By reviewing a range of bone remodeling models, we show the necessity for tailor-made mathematical models to decipher their roots and enhance patient treatment strategies. Collaboration among scientists from various domains is pivotal to surmount these challenges, ensuring improved accuracy and applicability of mathematical models. Ultimately, this effort aims to deepen our understanding of bone remodeling processes and their broader implications for diverse health conditions.

Sensing the future: A review on emerging technologies for assessing and monitoring bone health

Bone health is crucial at all stages of life. Several medical conditions and changes in lifestyle affect the growth, structure, and functions of bones. This may lead to the development of bone degenerative disorders, such as osteoporosis, osteoarthritis, rheumatoid arthritis, etc., which are major public health concerns worldwide. Accurate and reliable measurement and monitoring of bone health are important aspects for early diagnosis and interventions to prevent such disorders. Significant progress has recently been made in developing new sensing technologies that offer non-invasive, low-cost, and accurate measurements of bone health. In this review, we have described bone remodeling processes and common bone disorders. We have also compiled information on the bone turnover markers for their use as biomarkers in biosensing devices to monitor bone health. Second, this review details biosensing technology for bone health assessment, including the latest developments in various non-invasive techniques, including dual-energy X-ray absorptiometry, magnetic resonance imaging, computed tomography, and biosensors. Further, we have also discussed the potential of emerging technologies, such as biosensors based on nano- and micro-electromechanical systems and application of artificial intelligence in non-invasive techniques for improving bone health assessment. Finally, we have summarized the advantages and limitations of each technology and described clinical applications for detecting bone disorders and monitoring treatment outcomes. Overall, this review highlights the potential of emerging technologies for improving bone health assessment with the potential to revolutionize clinical practice and improve patient outcomes. The review highlights key challenges and future directions for biosensor research that pave the way for continued innovations to improve diagnosis, monitoring, and treatment of bone-related diseases.

Gene Expression Modulation of Markers Involved in Bone Formation and Resorption by Bisphenol A, Bisphenol F, Bisphenol S, and Bisphenol AF

BACKGROUND

Bisphenol A (BPA) and its analogs (BPF, BPS, and BPAF) are recognized for inducing detrimental effects on various tissues, including bone.

OBJECTIVES

The aim of this study is to investigate their impact on information and repair processes, specifically focusing on vascular endothelial growth factor (VEGF), transforming growth factor β1 (TGF-β1), and the receptors for transforming growth factor β (TGFR1, TGFR2, and TGFR3).

METHODS

Human osteoblasts isolated through primary culture from bone samples of healthy volunteers were subjected to cultivation in the presence of various dosage levels (10-5, 10-6, or 10-7 M) of BPA, BPF, BPS, or BPAF for 24 h. Gene expressions of RANKL, OPG, TGF-β1, TGFR1, TGFR2, TGFR3, and VEGF were analyzed by real-time polymerase chain reaction (RT-PCR). All experiments included untreated cells as controls.

RESULTS

Expressions of RANKL and OPG were dose-dependently downregulated by the presence of all tested bisphenols (BPs) except for BPAF, whose presence upregulated OPG expression at all three doses. TGF-β1 expression was downregulated by all BP treatments, and TGF-β1 receptor expression was also downregulated as a function of the BP and dose. VEGF expression was downregulated in the presence of BPF and BPAF at all three doses and in the presence of BPA at the two higher doses (10-5, and 10-6 M), but it was not changed by the presence of BPS at any dose.

CONCLUSIONS

The inhibition of both RANKL and OPG by the BPs, with a higher %inhibition of RANKL than of OPG, appears to rule out BP-induced activation of osteoclastogenesis via RANKL/RANK/OPG. Nevertheless, the effect of the BPs on the expression by osteoblasts of TGF-β1, TGF-β receptors, and VEGF indicates that these compounds can be responsible for major molecular changes in this cell population, contributing to their adverse effects on bone tissue.

Methotrexate inhibits glucocorticoids-induced osteoclastogenesis via activating IFN-γR/STAT1 pathway in the treatment of rheumatoid arthritis

OBJECTIVES

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterised by the synovitis and bone erosion. The combination therapy of glucocorticoids (GCs) and methotrexate (MTX) is recommended in early RA management, although the precise underlying mechanism of action remains unclear. This study is aimed to clarify the mechanism of MTX in combined with GC in treating RA.

METHODS

GC-induced osteoporosis (GIOP) mouse model was used to investigate the bone-protective role of MTX. Lipopolysaccharide-induced arthritis mouse model was used to evaluate the anti-inflammatory effects of GCs and MTX. Functional role of MTX on osteoclastogenesis was assessed by trap staining and micro-computer tomography. Western blot, RT-qPCR and coimmunoprecipitation were used to explore the underlying mechanisms.

RESULTS

We demonstrate that GCs, but not MTX, rapidly inhibited synovitis in arthritis model. MTX treatment was observed to inhibit osteoclastogenesis induced by GC in vitro and mitigate bone loss attributed by GIOP. GCs were found to augment the interaction between the membrane GC receptor (mGR) and signal transducer and activator of transcription 1 (STAT1), leading to the suppression of IFN-γR/STAT1 signalling pathways. Interestingly, MTX was found to inhibit osteoclastogenesis induced by GCs through the enhancement of the A2AR and IFN-γR interaction, thereby activating the IFN-γR/STAT1 signalling cascade. Consequently, this process results in a reduction in the mGR and STAT1 interaction.

CONCLUSIONS

Our study provides compelling evidence that MTX can make GCs effectively to suppress synovitis and reduce bone loss induced by GCs. This sheds light on the potential mechanistic insights underlying the efficacy of GCs in conjunction with MTX for treating RA.

Glucocorticoids disrupt longitudinal advance of cortical bone basic multicellular units in the rabbit distal tibia

Glucocorticoids (GCs) are the leading cause of secondary osteoporosis. The emerging perspective, derived primarily from 2D histological study of trabecular bone, is that GC-induced bone loss arises through the uncoupling of bone formation and resorption at the level of the basic multicellular unit (BMU), which carries out bone remodeling. Here we explore the impact of GCs on cortical bone remodeling in the rabbit model. Based upon the rapid reduction of bone formation and initial elevation of resorption caused by GCs, we hypothesized that the rate of advance (longitudinal erosion rate; LER) of cortical BMUs would be increased. To test this hypothesis we divided 20 female New Zealand White rabbits into four experimental groups: ovariohysterectomy (OVH), glucocorticoid (GC), OVH + GC and SHAM controls (n = 5 animals each). Ten weeks post-surgery (OVH or sham), and two weeks after the initiation of dosing (daily subcutaneous injections of 1.5 mg/kg of methylprednisolone sodium succinate in the GC-treated groups and 1 ml of saline for the others), the right tibiae were scanned in vivo using Synchrotron Radiation (SR) in-line phase contrast micro-CT at the Canadian Light Source. After an additional 2 weeks of dosing, the rabbits were euthanized and ex vivo images were collected using desktop micro-CT. The datasets were co-registered in 3D and LER was calculated as the distance traversed by BMU cutting-cones in the 14-day interval between scans. Counter to our hypothesis, LER was greatly reduced in GC-treated rabbits. Mean LER was lower in GC (4.27 μm/d; p < 0.001) and OVH + GC (4.19 μm/d; p < 0.001), while similar in OVH (40.13 μm/d; p = 0.990), compared to SHAM (40.44 μm/d). This approximately 90 % reduction in LER with GCs was also associated with an overall disruption of BMU progression, with radial expansion of the remodeling space occurring in all directions. This unexpected outcome suggests that GCs do not simply uncouple formation and resorption within cortical BMUs and highlights the value of the time-lapsed 4D approach employed.

The Effect of Marginal Zn2+ Excess Released from Titanium Coating on Differentiation of Human Osteoblastic Cells

Composite coatings based on chitosan and zinc nanoparticles (ZnNPs) were successfully produced on Ti13Zr13Nb substrates by cathodic electrophoretic deposition (EPD). The unfavorable phenomenon of water electrolysis-induced nonuniformity was reduced by applying a low voltage (20 V) and a short deposition time (1 min). Surface analysis (roughness and hydrophilicity) reveals the potential of these coatings for enhancing cell attachment and bone-implant integration. However, there is a concern about adhesion and strength; therefore, incorporating ZnNPs shows promise for enhancing mechanical properties, suggesting opportunities for further optimization of the process. The aim of this work was to investigate whether Zn2+ released from coating yields overt cellular impairment. hFOB1.19 osteoblastic cells were used as a model in this study. A subtoxic, 0.125 mmol/L, Zn concentration did not cause significant negative changes in cultured osteoblastic cells, as there was no significant change in their viability and their mitochondrial metabolism. Moreover, the alkaline phosphatase and lactate dehydrogenase activities were aggravated. However, a high, over 0.175 mmol/L, Zn2+ concentration caused total cell death. This was caused by the inhibition of mitochondrial enzymes' activities. Our data indicate that composite coatings releasing Zn2+ may be used as the differentiating factor toward osteoblastic cells.

The age-related effects on orthodontic tooth movement and the surrounding periodontal environment

Orthodontic treatment in adults is often related to longer treatment time as well as higher periodontal risks compared to adolescents. The aim of this review is to explore the influence of age-related chages on orthodontic tooth movement (OTM) from macro and micro perspectives. Adults tend to show slower tooth movement speed compared to adolescence, especially during the early phase. Under orthodontic forces, the biological responses of the periodontal ligament (PDL) and alveolar bone is different between adult and adolescents. The adult PDL shows extended disorganization time, increased cell senescence, less cell signaling and a more inflammatory microenvironment than the adolescent PDL. In addition, the blood vessel surface area is reduced during the late movement phase, and fiber elasticity decreases. At the same time, adult alveolar bone shows a higher density, as well as a reduced osteoblast and osteoclast activation, under orthodontic forces. The local cytokine expression also differs between adults and adolescents. Side-effects, such as excessive root resorption, greater orthodontic pain, and reduced pulpal blood flow, also occur more frequently in adults than in adolescents.

Low-dose radiation-induced SUMOylation of NICD1 negatively regulates osteogenic differentiation in BMSCs

Various biological effects of ionizing radiation, especially continuous exposure to low-dose radiation (LDR), have attracted considerable attention. Impaired bone structure caused by LDR has been reported, but little is known about the mechanism involved in the disruption of bone metabolism. In this study, given that LDR was found to (at a cumulative dose of 0.10 Gy) disturb the serum Mg2+ level and Notch1 signal in the mouse femur tissues, the effects of LDR on osteogenesis and the underlying molecular mechanisms were investigated based on an in vitro culture system for bone marrow stromal cells (BMSCs). Our data showed that cumulative LDR suppressed the osteogenic potential in BMSCs as a result of upregulation of Notch1 signaling. Further analyses indicated that the upregulation of NICD1 (Notch1 intracellular domain), the key intracellular domain for Notch1 signaling, under LDR was a consequence of enhanced protein stabilization caused by SUMOylation (small ubiquitin-like modification). Specifically, the downregulation of SENP1 (sentrin/SUMO-specific protease 1) expression induced by LDR enhanced the SUMOylation of NICD1, causing the accumulation of Notch1 signaling, which eventually inhibited the osteogenic potential of BMSCs. In conclusion, this work expounded on the mechanisms underlying the impacts of LDR on bone metabolism and shed light on the research on bone regeneration under radiation.

Gut microbiome-targeted therapies and bone health across the lifespan: a scoping review

Emerging evidence suggests that bone turnover is influenced by the gut microbiome through critical bone signaling pathways. The purpose of this scoping review is to examine prebiotic, probiotic, and synbiotic interventions on bone outcomes in humans across the lifespan. PubMed, Scopus, and EBSCOhost were searched until January 2023 to identify clinical trials examining bone mineral density (BMD) or bone mineral content (BMC) with gut microbiome interventions. Of three prebiotic interventions, one reported higher areal BMD (aBMD) in adolescents. In two studies in postmenopausal women, no changes in aBMD were observed despite decreased biomarkers of bone resorption. Probiotic interventions in perimenopausal or postmenopausal women demonstrated increased aBMD or attenuated bone loss in various bone regions. All studies observed attenuated bone loss (n = 4) or increased aBMD (n = 1). One study assessed a synbiotic intervention on aBMD and observed decreased biomarkers of bone resorption but no changes in aBMD. Results suggest potential for microbiome-targeted therapies (prebiotics, probiotics and synbiotics) to attenuate bone loss. However, changes in biomarkers of bone turnover were not always accompanied by changes in bone mineralization. Future studies should utilize longer duration interventions to investigate the influence of prebiotic, probiotic, and synbiotic interventions across diverse age, sex, and ethnic cohorts.

The Effects of Chronic Psychostimulant Administration on Bone Health: A Review

(1) Background: Methylphenidate (MP) and amphetamine (AMP) are psychostimulants that are widely prescribed to treat Attention Deficit Hyperactivity Disorder (ADHD) and narcolepsy. In recent years, 6.1 million children received an ADHD diagnosis, and nearly 2/3 of these children were prescribed psychostimulants for treatment. The purpose of this review is to summarize the current literature on psychostimulant use and the resulting effects on bone homeostasis, biomechanical properties, and functional integrity. (2) Methods: Literature searches were conducted from Medline/PubMed electronic databases utilizing the search terms "methylphenidate" OR "amphetamine" OR "methylphenidate" AND "bone health" AND "bone remodeling" AND "osteoclast" AND "osteoblast" AND "dopamine" from 01/1985 to 04/2023. (3) Results: Of the 550 publications found, 44 met the inclusion criteria. Data from identified studies demonstrate that the use of MP and AMP results in decreases in specific bone properties and biomechanical integrity via downstream effects on osteoblasts and osteoclast-related genes. (4) Conclusions: The chronic use of psychostimulants negatively affects bone integrity and strength as a result of increased osteoclast activity. These data support the need to take this into consideration when planning the treatment type and duration for bone fractures.

Evaluation of Integrity of Allogeneic Bone Processed with High Hydrostatic Pressure: A Pilot Animal Study

Processing of bone allografts with strong acids and γ-sterilization results in decreased biomechanical properties and reduction in osteogenecity and osteoconductivity. High hydrostatic pressure (HHP) treatment could be a gentle alternative to processing techniques usually applied. HHP is known to induce devitalization of cancellous bone while preserving biomechanical stability and molecules that induce cell differentiation. Here, a specific HHP protocol for devitalization of cancellous bone was applied to rabbit femoral bone. Allogeneic bone cylinders were subsequently implanted into a defect in the lateral condyles of rabbit femora and were compared to autologous bone grafts. Analysis of bone integration 4 and 12 weeks postoperatively revealed no differences between autografts and HHP-treated allografts regarding the expression of genes characteristic for bone remodeling, showing expression niveous comparable to original bone cylinder. Furthermore, biomechanical properties were evaluated 12 weeks postoperatively. Autografts and HHP-treated allografts both showed a yield strength ranging between 2 and 2.5 MPa and an average bone mass density of 250 mg/cm2. Furthermore, histological analysis of the region of interest revealed a rate of 5 to 10% BPM-2 and approximately 40% osteocalcin-positive staining, with no marked differences between allografts and autografts demonstrating comparable matrix deposition in the graft region. A suitable graft integrity was pointed out by μCT imaging in both groups, supporting the biomechanical data. In summary, the integrity of HHP-treated cancellous bone allografts showed similar results to untreated autografts. Hence, HHP treatment may represent a gentle and effective alternative to existing processing techniques for bone allografts.

Changes in RANKL, OPG, and 25(OH)D Levels in Children with Leukemia from Diagnosis to Remission

BACKGROUND

The receptor activator of the nuclear factor-kB (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) pathway is a determining pathway in the balance between bone formation and resorption, and disruptions in this complex can affect bone metabolism.

METHODS

This study analyzes the changes in RANKL, OPG, and 25(OH)D levels; the RANKL/OPG ratio; and other bone turnover markers (BTMs) from diagnosis to complete remission in children with acute lymphoblastic leukemia (ALL). This is a prospective observational cohort study, carried out at the Instituto Mexicano del Seguro Social, Mexico City, including 33 patients (4-17 years) with newly diagnosed B-cell ALL. The patients were treated with the HP09 chemotherapy protocol. Children who had previously been treated with corticosteroids were excluded. A peripheral blood sample at diagnosis and remission was collected to determine the 25(OH)D and BTM concentrations.

RESULTS

Increased RANKL (p = 0.001) and osteocalcin (p < 0.001) levels and RANKL/OPG ratio (<0.001) and a decreased OPG level (p = 0.005) were observed at remission, predominantly in the high-risk (HR) relapse and vitamin D deficiency groups. A negative association between RANKL and OPG (r = -0.454, p = 0.008) was observed.

CONCLUSIONS

we suggest that the RANKL/OPG ratio could serve as a bone remodeling marker in ALL patients.

Femora nutrient foramina and aerobic capacity in giant extinct xenarthrans

Nutrient foramina are small openings in the periosteal surface of the mid-shaft region of long bones that traverse the cortical layer and reach the medullary cavity. They are important for the delivery of nutrients and oxygen to bone tissue and are crucial for the repair and remodeling of bones over time. The nutrient foramina in the femur's diaphysis are related to the energetic needs of the femur and have been shown to be related to the maximum metabolic rate (MMR) of taxa. Here, we investigate the relationship between nutrient foramen size and body mass as a proxy to the aerobic capacity of taxa in living and extinct xenarthrans, including living sloths, anteaters, and armadillos, as well as extinct xenarthrans such as glyptodonts, pampatheres, and ground sloths. Seventy femora were sampled, including 20 from extant taxa and 50 from extinct taxa. We obtained the blood flow rate (Q̇) based on foramina area and performed PGLS and phylogenetic ANCOVA in order to explore differences among mammalian groups. Our results show that, among mammals, taxa commonly associated with lower metabolism like living xenarthrans showed relatively smaller foramina, while the foramina of giant extinct xenarthrans like ground sloths and glyptodonts overlapped with non-xenarthran placentals. Consequently, Q̇ estimations indicated aerobic capacities comparable to other placental giant taxa like elephants or some ungulates. Furthermore, the estimation of the MMR for fossil giant taxa showed similar results, with almost all taxa showing high values except for those for which strong semi-arboreal or fossorial habits have been proposed. Moreover, the results are compatible with the diets predicted for extinct taxa, which indicate a strong consumption of grass similar to ungulates and in contrast to the folivorous or insectivorous diets of extant xenarthrans. The ancestral reconstruction of the MMR values indicated a lack of a common pattern for all xenarthrans, strongly supporting the occurrence of low metabolic rates in extant forms due to their particular dietary preferences and arboreal or fossorial habits. Our results highlight the importance of considering different evidence beyond the phylogenetic position of extinct taxa, especially when extinct forms are exceptionally different from their extant relatives. Future studies evaluating the energetic needs of giant extinct xenarthrans should not assume lower metabolic rates for these extinct animals based solely on their phylogenetic position and the observations on their extant relatives.

Six months of voluntary alcohol consumption in male cynomolgus macaques reduces intracortical bone porosity without altering mineralization or mechanical properties

Chronic heavy alcohol consumption is a risk factor for low trauma bone fracture. Using a non-human primate model of voluntary alcohol consumption, we investigated the effects of 6 months of ethanol intake on cortical bone in cynomolgus macaques (Macaca fascicularis). Young adult (6.4 ± 0.1 years old, mean ± SE) male cynomolgus macaques (n = 17) were subjected to a 4-month graded ethanol induction period, followed by voluntary self-administration of water or ethanol (4 % w/v) for 22 h/d, 7 d/wk. for 6 months. Control animals (n = 6) consumed an isocaloric maltose-dextrin solution. Tibial response was evaluated using densitometry, microcomputed tomography, histomorphometry, biomechanical testing, and Raman spectroscopy. Global bone response was evaluated using biochemical markers of bone turnover. Monkeys in the ethanol group consumed an average of 2.3 ± 0.2 g/kg/d ethanol resulting in a blood ethanol concentration of 90 ± 12 mg/dl in longitudinal samples taken 7 h after the daily session began. Ethanol consumption had no effect on tibia length, mass, density, mechanical properties, or mineralization (p > 0.642). However, compared to controls, ethanol intake resulted in a dose-dependent reduction in intracortical bone porosity (Spearman rank correlation = -0.770; p < 0.0001) and compared to baseline, a strong tendency (p = 0.058) for lower plasma CTX, a biochemical marker of global bone resorption. These findings are important because suppressed cortical bone remodeling can result in a decrease in bone quality. In conclusion, intracortical bone porosity was reduced to subnormal values 6 months following initiation of voluntary ethanol consumption but other measures of tibia architecture, mineralization, or mechanics were not altered.

Effects of Endocrine-Disrupting Chemicals on Bone Health

This comprehensive review critically examines the detrimental impacts of endocrine-disrupting chemicals (EDCs) on bone health, with a specific focus on substances such as bisphenol A (BPA), per- and polyfluoroalkyl substances (PFASs), phthalates, and dioxins. These EDCs, by interfering with the endocrine system's normal functioning, pose a significant risk to bone metabolism, potentially leading to a heightened susceptibility to bone-related disorders and diseases. Notably, BPA has been shown to inhibit the differentiation of osteoblasts and promote the apoptosis of osteoblasts, which results in altered bone turnover status. PFASs, known for their environmental persistence and ability to bioaccumulate in the human body, have been linked to an increased osteoporosis risk. Similarly, phthalates, which are widely used in the production of plastics, have been associated with adverse bone health outcomes, showing an inverse relationship between phthalate exposure and bone mineral density. Dioxins present a more complex picture, with research findings suggesting both potential benefits and adverse effects on bone structure and density, depending on factors such as the timing and level of exposure. This review underscores the urgent need for further research to better understand the specific pathways through which EDCs affect bone health and to develop targeted strategies for mitigating their potentially harmful impacts.

A Mathematical Model for Fibrous Dysplasia: The Role of the Flow of Mutant Cells

Fibrous dysplasia (FD) is a mosaic non-inheritable genetic disorder of the skeleton in which normal bone is replaced by structurally unsound fibro-osseous tissue. There is no curative treatment for FD, partly because its pathophysiology is not yet fully known. We present a simple mathematical model of the disease incorporating its basic known biology, to gain insight on the dynamics of the involved bone-cell populations, and shed light on its pathophysiology. We develop an analytical study of the model and study its basic properties. The existence and stability of steady states are studied, an analysis of sensitivity on the model parameters is done, and different numerical simulations provide findings in agreement with the analytical results. We discuss the model dynamics match with known facts on the disease, and how some open questions could be addressed using the model.

Osteostaticytes: A novel osteoclast subset couples bone resorption and bone formation

BACKGROUND

Osteomyelitis (OM) is an inflammatory condition of bone characterized by cortical bone devascularization and necrosis. Dysregulation of bone remodelling is triggered by OM. Bone remodelling is precisely coordinated by bone resorption and formation via a reversal phase. However, the cellular and molecular mechanisms underlying bone remodelling failure after osteomyelitis remain elusive.

METHODS

To elucidate the cellular and molecular mechanism underlying bone healing after osteomyelitis, we employed single-cell RNA sequencing (scRNA-seq) to depict the atlas of human cortical bone in normal, infected and reconstructed states. Dimensionality reduction by t-stochastic neighbourhood embedding (t-SNE) and graph-based clustering were applied to analyse the detailed clusters of osteoclast lineages. After trajectory analysis of osteoclast lineages over pseudotime, real-time PCR and immunofluorescence (IF) staining were applied to identify marker gene expression of various osteoclast lineages in the osteoclast induction model and human bone sections, respectively. The potential function and communication of osteoclasts were analysed via gene set enrichment analysis (GSEA) and CellChat. The chemotactic ability of mesenchymal stem cells (MSCs) and osteoclast lineage cells in various differentiation states was determined by transwell assays and coculture assays. The effects of various osteoclast lineages on the osteogenic differentiation potential of MSCs were also determined by using this coculture system. A normal mouse tibia fracture model and an osteomyelitis-related tibia fracture model were generated via injection of luciferase-labelled Staphylococcus aureus to verify the relationships between a novel osteoclast lineage and MSCs. Then, the infection was detected by a bioluminescence imaging system. Finally, immunofluorescence staining was used to detect the expression of markers of MSCs and novel osteoclast lineages in different remodelling phases in normal and infected bone remodelling models.

RESULTS

In this study, we constructed a cell atlas encompassing normal, infected, and reconstructed cortical bone. Then, we identified a novel subset at the earlier stage of the osteoclast lineage that exhibited increased expression of IDO1, CCL3, and CCL4. These IDO1highCCL3highCCL4high cells, termed osteostaticytes (OSCs), were further regarded as the reservoir of osteoclasts in the reversal phase. Notably, OSCs exhibited the highest chemotactic activity, surpassing other lineage subsets. We also discovered that cells at the earlier stage of the osteoclast lineage play a significant role in recruiting mesenchymal stem cells (MSCs). Finally, the data revealed that OSCs might be positively related to the occurrence of bone MSCs and the contribution of bone remodelling.

CONCLUSION

Collectively, our findings revealed a novel stage (OSC) within the osteoclast lineage, potentially representing elusive bone reversal cells due to its increased chemotactic ability towards MSCs and potential contribution to bone remodelling. This study provides valuable insights into the intricate mechanisms of the reversal phase during bone remodelling and unveils potential therapeutic strategies for diseases associated with bone uncoupling.

TRANSLATIONAL POTENTIAL OF THIS ARTICLE

This study identified a new subset, referred to as IDO1(plus symbol) CCL3(plus symbol) CCL4(plus symbol) osteostaticytes which displayed the highest chemotactic activity among all osteoclast lineages and may serve as reversal cells in bone remodelling. These findings offer new insights and insights for understanding bone reversal-related diseases and may serve as novel therapeutic targets for conditions such as osteomyelitis and delayed bone healing.

Hormonal Control of Bone Architecture Throughout the Lifespan: Implications for Fracture Prediction and Prevention

BACKGROUND

Skeletal modeling in childhood and adolescence and continuous remodeling throughout the lifespan are designed to adapt to a changing environment and resist external forces and fractures. The flux of sex steroids in men and women, beginning from fetal development and evolving through infancy, childhood, puberty, young adulthood, peri/menopause transition, and postmenopause, is critical for bone size, peak bone mass, and fracture resistance.

OBJECTIVE

This review will highlight how changes in sex steroids throughout the lifespan affect bone cells and the consequence of these changes on bone architecture and strength.

METHODS

Literature review and discussion.

RESULTS

The contributions of estrogen and testosterone on skeletal development have been difficult to study due to the reciprocal and intertwining contributions of one on the other. Although orchiectomy in men renders circulating testosterone absent, circulating estrogen also declines due to testosterone being the substrate for estradiol. The discovery of men with absent estradiol or resistance to estrogen and the study of mouse models led to the understanding that estrogen has a larger direct role in skeletal development and maintenance in men and women. The mechanistic reason for larger bone size in men is incompletely understood but related to indirect effects of testosterone on the skeleton, such as higher muscle mass leading to larger mechanical loading. Declines in sex steroids during menopause in women and androgen deprivation therapies in men have profound and negative effects on the skeleton. Therapies to prevent such bone loss are available, but how such therapies can be tailored based on bone size and architecture remains an area of investigation.

CONCLUSION

In this review, the elegant interplay and contribution of sex steroids on bone architecture in men and women throughout the lifespan is described.

Cigarette smoke promotes IL-6-dependent lung cancer migration and osteolytic bone metastasis

Lung cancer stands as a major contributor to cancer-related fatalities globally, with cigarette smoke playing a pivotal role in its development and metastasis. Cigarette smoke is also recognized as a risk factor for bone loss disorders like osteoporosis. However, the association between cigarette smoke and another bone loss disorder, lung cancer osteolytic bone metastasis, remains largely uncertain. Our Gene Set Enrichment Analysis (GSEA) indicated that smokers among lung cancer patients exhibited higher expression levels of bone turnover gene sets. Both The Cancer Genome Atlas (TCGA) database and our clinic samples demonstrated elevated expression of the osteolytic factor IL-6 in ever-smokers with bone metastasis among lung cancer patients. Our cellular experiments revealed that benzo[α]pyrene (B[α]P) and cigarette smoke extract (CSE) promoted IL-6 production and cell migration in lung cancer. Activation of the PI3K, Akt, and NF-κB signaling pathways was involved in cigarette smoke-augmented IL-6-dependent migration. Additionally, cigarette smoke lung cancer-secreted IL-6 promoted osteoclast formation. Importantly, blocking IL-6 abolished cigarette smoke-facilitated lung cancer osteolytic bone metastasis in vivo. Our findings provide evidence that cigarette smoke is a risk factor for osteolytic bone metastasis. Thus, inhibiting IL-6 may be a valuable therapeutic strategy for managing osteolytic bone metastasis in lung cancer patients who smoke.

Enhancing Guided Bone Regeneration with a Novel Carp Collagen Scaffold: Principles and Applications

Bone defects resulting from trauma, surgery, and congenital, infectious, or oncological diseases are a functional and aesthetic burden for patients. Bone regeneration is a demanding procedure, involving a spectrum of molecular processes and requiring the use of various scaffolds and substances, often yielding an unsatisfactory result. Recently, the new collagen sponge and its structural derivatives manufactured from European carp (Cyprinus carpio) were introduced and patented. Due to its fish origin, the novel scaffold poses no risk of allergic reactions or transfer of zoonoses and additionally shows superior biocompatibility, mechanical stability, adjustable degradation rate, and porosity. In this review, we focus on the basic principles of bone regeneration and describe the characteristics of an "ideal" bone scaffold focusing on guided bone regeneration. Moreover, we suggest several possible applications of this novel material in bone regeneration processes, thus opening new horizons for further research.

Targeted delivery of anti-osteoporosis therapy: Bisphosphonate-modified nanosystems and composites

Osteoporosis (OP) constitutes a significant health concern that profoundly affects individuals' quality of life. Bisphosphonates, conventional pharmaceuticals widely employed in OP treatment, encounter limitations related to inadequate drug targeting and a short effective duration, thereby compromising their clinical efficacy. The burgeoning field of nanotechnology has witnessed the development and application of diverse functional nanosystems designed for OP treatment. Owing to the bone tissue affinity of bisphosphonates, these nanosystems are modified to address shortcomings associated with traditional drug delivery. In this review, we explore the potential of bisphosphonate-modified nanosystems as a promising strategy for addressing osteoporotic conditions. With functional modification, these nanosystems exhibit a targeted and reversible effect on osteoporotic remodeling, presenting a promising solution to enhance precision in drug delivery. The synthesis methods, physicochemical properties, and in vitro/in vivo performance of bisphosphonate-modified nanosystems are comprehensively examined in this review. Through a thorough analysis of recent advances and accomplishments in this field, we aim to provide insights into the potential applications and future directions of bisphosphonate-modified nanosystems for targeted and reversible osteoporotic remodeling.