Bone Disease Research Articles

Metabolic bone diseases : what's new in 2024

The epidemiology of femoral fractures is changing, with more femoral shaft fractures linked to high-risk physical exercise by an older population. Vitamin D given during pregnancy for the mother's health could benefit the child. Zoledronic acid is the most effective bisphosphonate. It should be given during hospitalization to people suffering from hip fractures. Denosumab should not be used in patients with severe renal failure. When denosumab is discontinued, management of the rebound effect requires bone resorption markers to be kept at very low levels to maintain the bone mass gained as much as possible. Finally, progress continues to be made in the treatment of rare bone diseases.

Is There a Role for Daratumumab Retreatment in Patients with Relapsed/Refractory Multiple Myeloma?

Multiple myeloma (MM) is a hematologic disease characterized by the clonal expansion of malignant plasma cells that accumulate in the bone marrow, leading to osteolytic bone disease, hypercalcemia, anemia, and renal dysfunction. Daratumumab was the first monoclonal anti-CD38 antibody approved for the treatment of MM, initially in relapse/refractory settings and, more recently, for newly diagnosed patients. Increased first-line usage of daratumumab will also substantially change treatment approaches for patients with relapsed/refractory disease. Due to the cost and availability of bispecific T cell redirecting antibodies (BsAbs) and chimeric antigen receptor T cell therapy (CAR-T) in real-life settings in many countries, retreatment with daratumumab in subsequent lines of therapy might be a reasonable choice. Data regarding efficacy and optimal combinations of daratumumab retreatment are lacking, and here we provide a short literature review of available data. We identified only a small number of articles based on retrospective analysis of medical records in real-life settings. A strong consistency in results regarding response rates and treatment duration was noticed among mainly heavily pre-treated MM patients, with approximately half of patients achieving at least partial remission (PR) after retreatment with daratumumab-based protocol. The duration of treatment and time to the next treatment for retreatment episodes were considerable and consistent with clinical expectations for later lines of therapy. The analysis of data in this literature review indicates that daratumumab retreatment may provide meaningful clinical benefit to some patients with relapsed/refractory MM despite having prior exposure. However, further research is needed to identify clinical and biological parameters that may predict favorable responses to daratumumab retreatment.

DAMPs, PAMPs, NLRs, RIGs, CLRs and TLRs - Understanding the Alphabet Soup in the Context of Bone Biology.

The purpose of this review is to summarize the current understanding of cell-autonomous innate immune pathways that contribute to bone homeostasis and disease. Germ-line encoded pattern recognition receptors (PRRs) are the first line of defense against danger and infections. In the bone microenvironment, PRRs and downstream signaling pathways, that mount immune defense, interface intimately with the core cellular processes in bone cells to alter bone formation and resorption. The role of PRR engagement on bone remodeling has been best described as a result of activated macrophages secreting effector molecules that reshape the characteristics of bone-resident cells. However, it is being increasingly recognized that local bone resident-cells like osteoclasts and osteoblasts possess an arsenal of PRRs. The engagement of these PRRs by stimuli in the bone niche can drive cell-autonomous (aka cell-intrinsic) responses that, in turn, impact bone-remodeling dramatically, irrespective of immune cell effectors. Indeed, this vital role for cell-autonomous innate immune responses is evident in how reduced PRR activity within osteoclast progenitors correlates with their reduced differentiation and abnormal bone remodeling. Further, cell-intrinsic PRR activity has now been shown to influence the behavior of osteoblasts, osteocytes and other local immune/non-immune cell populations. However, distinct PRR families have varying impact on bone homeostasis and inflammation, emphasizing the importance of investigating these different nodes of innate immune signaling in bone cells to better identify how they synergistically and/or antagonistically regulate bone remodeling in the course of an immune response. Innate immune sensing within bone resident cells is a critical determinant for bone remodeling in health and disease.

Biomimetic Extracellular Vesicles Containing Biominerals for Targeted Osteoporosis Therapy.

Osteoporosis (OP) is a systemic skeletal disorder characterized by decreased bone mineral density and a heightened risk of fractures. Therapies for OP have primarily focused on balancing bone formation and bone resorption, but enhancing the remineralization of osteoporotic bone is also a key strategy for effective repair. Recent insights into biomineralization mechanisms have highlighted the essential role of mineral-containing extracellular vesicles (EVs) secreted by osteoblasts in promoting bone marrow mesenchymal stromal/stem cell (BMSC) differentiation and initiating matrix mineralization. Drawing from these principles, we developed a biomimetic approach to replicate the structure and function of the osteoblast-derived EVs by engineering biomimetic mitochondrial minerals with bone marrow homing cell membranes (CMs). This bone-targeted biomimetic system exhibits excellent biocompatibility, enhancing osteogenic differentiation and stimulating angiogenesis by regulating cellular energy metabolism. Additionally, the CM-coated structure shows affinity for collagen fibrils, effectively enhancing intrafibrillar collagen mineralization, thereby facilitating osteoporotic bone repair. Overall, the biomimetic system offers a safe and efficient therapeutic alternative, positioning it as a platform for bone tissue engineering and regenerative medicine.

Associated diseases and their effects on disease course in patients with chronic non-bacterial osteomyelitis: retrospective experience from a single center.

Chronic non-bacterial osteomyelitis (CNO) is a rare autoinflammatory bone disease associated with other chronic inflammatory diseases such as familial Mediterranean fever (FMF), juvenile idiopathic arthritis (JIA), spondylarthropathies, inflammatory bowel disease (IBD), and pyoderma gangrenosum. We aimed to describe the clinical and follow-up characteristics of patients with CNO and to compare findings between patients with and without comorbidities. The clinical records of patients with CNO who were followed up in our pediatric rheumatology clinic between 2018 and 2023 were reviewed. Patients were divided into two groups according to the presence or absence of comorbidities. The clinical, laboratory, and radiological characteristics and treatments of the groups were compared. The study included 40 patients (65% male) diagnosed with CNO. The median (IQR) age at symptom onset was 10 (6.4) and at diagnosis was 11.5 (5.9) years. Fourteen (35%) patients had comorbidities. The comorbidities were FMF (n = 9), IBD (n = 3), uveitis (n = 3), psoriasis (n = 1) and acne conglabatae (n = 2). The group with comorbidities had higher number of bones involved (3 or more bones) (78.6% versus 42.3%) (p = 0.028), and 78.6% of patients with comorbidities received biologic treatment, while only 23.1% of patients without comorbidities were treated with biologics (p = 0.001). Familial Mediterranean fever, uveitis, IBD, psoriasis and acne conglabata were found to be the clinical conditions associated with CNO. Patients with CNO who had comorbidities appeared to have a more severe phenotype of the disease accompanied with more bone involvement and requiring more biologic treatment. Key Points • Chronic non-bacterial osteomyelitis (CNO), an auto-inflammatory bone disease, can be seen in association with other inflammatory conditions such as familial Mediterranean fever (FMF), uveitis, inflammatory bowel disease (IBD), psoriasis, and acne conglobata. • If CNO is associated with another inflammatory disease, the number of bones involved may be higher and patients may need more intensive treatments, such as biologics. • CNO may coexist with one or more inflammatory diseases, which may exacerbate the disease phenotype.

The effect of LARP7 on gene expression during osteogenesis.

La-related protein 7 (LARP7) is a key regulator of RNA metabolism and is thought to play a role in various cellular processes. LARP7 gene autosomal recessive mutations are the cause of Alazami syndrome, which presents with skeletal abnormalities, intellectual disabilities, and facial dysmorphisms. This study aimed to determine the role of LARP7 in modulating gene expression dynamics during osteogenesis. First, the temporal expression profile of the LARP7 gene during various stages of osteogenesis was examined. Then, RNA interference-mediated knockdown of LARP7 was implemented and high-throughput RNA-seq analysis was performed in order to identify global gene expression changes associated with knockdown of LARP7. The findings show there were significant alterations in the overall gene expression profile. The observed down-regulation in extracellular matrix (ECM) component genes suggests that it might lead to impairments in the structure and function of the bone matrix. Additionally, modulation of alternative splicing events were observed, especially in the RUNX2 and SPP1, indicating the potential contribution of LARP7 to the phenotypic features observed in Alazami syndrome. Overall, the findings clarify the regulatory mechanisms of LARP7 in osteogenic differentiation and illuminate potential avenues for therapeutic interventions in patients with skeletal disorders.

Pendulous crop in broilers: a literature review

Brazilian poultry farming stands out worldwide due to its high level of technological investment in all sectors of the production chain. Brazil is the largest exporter and second largest producer of broiler chickens, only behind the United States, ranked first. Chicken meat is one of the main sources of protein in the human diet and its importance is attributable to the continuous improvement of the zootechnical indices of this species. However, as genetic improvement makes it possible to select for higher production efficiency, it also has undesirable effects on physiological, immunological, welfare characteristics. Different metabolic and skeletal disorders have been described and associated with genetic, management and nutritional causes, such as ascitic syndrome, the etiology of which remains unknown, osteochondrosis of the femoral head, tibial dyschondroplasia and pectoral muscle disorders such as woody breast. In recent years, another metabolic disease has come to the attention: pendulous crop, characterized by temporary or permanent crop distension with the presence of liquid or semi-liquid content. This build-up results in inadequate functioning of the organ, and because it is irreversible, affected animals are discarded, causing serious economic damage. Studies on this disease are scarce in Brazil and around the world, which demonstrates the need for more research to elucidate the factors related to its etiopathogenesis. The aim of this study was to carry out a literature review on the disease, considering aspects related to the history and importance of poultry production, digestive physiology as well findings in birds affected by the disease.

Identification of a global gene expression signature associated with the genetic risk of catastrophic fracture in iPSC-derived osteoblasts from Thoroughbred horses.

Bone fractures are a significant problem in Thoroughbred racehorses. The risk of fracture is influenced by both genetic and environmental factors. To determine the biological processes that are affected in genetically susceptible horses, we utilised polygenic risk scoring to establish induced pluripotent stem cells (iPSCs) from horses at high and low genetic risk. RNA-sequencing on iPSC-derived osteoblasts revealed 112 genes that were significantly differentially expressed. Forty-three of these genes have known roles in bone, 27 are not yet annotated in the equine genome and 42 currently have no described role in bone. However, many of the proteins encoded by the known and unknown genes have reported interactions. Functional enrichment analyses revealed that the differentially expressed genes were overrepresented in processes regulating the extracellular matrix and pathways known to be involved in bone remodelling and bone diseases. Gene set enrichment analysis also detected numerous biological processes and pathways involved in glycolysis with the associated genes having a higher expression in the iPSC-osteoblasts from horses with low polygenic risk scores for fracture. Therefore, the differentially expressed genes may be relevant for maintaining bone homeostasis and contribute to fracture risk. A deeper understanding of the consequences of mis-regulation of these genes and the identification of the DNA variants which underpin their differential expression may reveal more about the molecular mechanisms which are involved in equine bone health and fracture risk.

Cytotoxic Activity of Bisphosphonic Derivatives Obtained by the Michaelis–Arbuzov or the Pudovik Reaction

Background: Methylenebisphosphonic derivatives including hydroxy-methylenebisphosphonic species may be of potential biological activity, and a part of them is used in the treatment of bone diseases. Methods: Methylenebisphosphonates may be obtained by the Michaelis–Arbuzov reaction of suitably α-substituted methylphosphonates and trialkyl phosphites or phosphinous esters, while the hydroxy-methylene variations are prepared by the Pudovik reaction of α-oxophosphonates and different >P(O)H reagents, such as diethyl phosphite and diarylphosphine oxides. Results: After converting α-hydroxy-benzylphosphonates and -phosphine oxides to the α-halogeno- and α-sulfonyloxy derivatives, they were utilized in the Michaelis–Arbuzov reaction with trialkyl phosphites and ethyl diphenylphosphinite to afford the corresponding bisphosphonate, bis(phosphine oxide) and phosphonate–phosphine oxide derivatives. The Pudovik approach led to α-hydroxy-methylenebisphosphonic species and to their rearranged products. A part of the derivatives revealed a significant cytotoxic effect on pancreatic adenocarcinoma or multiple myeloma cells. Conclusions: The new families of compounds synthesized by our novel approaches may be of practical importance due to the significant cytotoxic activity on the cell cultures investigated. Compounds lacking hydroxy groups showed anti-myeloma activity or limited effect on pancreatic cancer (PANC-1) cells unless substituted with para-trifluoromethyl group. Hydroxy-containing bisphosphonates and their rearranged derivatives demonstrated varying effects depending on structural modifications. While myeloma (U266) cells indicated greater sensitivity overall, the most significant reductions in cell viability were observed in PANC-1 cancer cells, raising potential therapeutic applications of bisphosphonates beyond myeloma-associated bone disease, particularly for malignancies like pancreatic ductal adenocarcinoma.

Identification of Novel and Rare GNAS Mutations in Craniofacial Fibrous Dysplasia.

Fibrous dysplasia (FD), caused by activating mutations of GNAS, is a skeletal disorder with considerable clinicopathological heterogeneity. Although prevalent mutations such as R201C and R201H dominate in FD, a limited number of rare mutations, including R201S, R201G, and Q227L, have been documented. The scarcity of information concerning these uncommon mutations motivates our investigation, seeking to enhance comprehension of this less-explored subgroup within FD. This study introduces three cases of craniofacial FD exhibiting rare GNAS mutations. Employing DNA sequencing on fresh frozen lesion tissues, we conducted a thorough analysis of clinical, radiological, and pathological features, delving into genotypic and phenotypic correlations. A comparative assessment with our previous series was also conducted. In the subset of patients subjected to DNA sequencing, a novel GNAS missense mutation (Q227E) was identified in one case, while a rare GNAS mutation (R201S) in exon 8 was found in the other two patients. Although no apparent phenotypic distinctions were observed among those with GNAS hotspot mutations (R201C, R201H), a more severe phenotype was discerned in the case featuring the novel GNAS mutation Q227E. This study marks the first report of the Q227E mutation in the GNAS gene associated with bone disease, enriching our understanding of FD's genetic basis and shedding light on the clinicopathological heterogeneity of craniofacial FD.

Preclinical evaluation of the efficacy and safety of AAV8-TNAP-D10 in Alpl-/- and AlplPrx1/Prx1 mouse models for the treatment of early and late-onset hypophosphatasia.

We previously documented successful resolution of skeletal and dental disease in the infantile and late-onset murine models of hypophosphatasia (HPP), with a single injection of an adeno-associated serotype 8 vector encoding mineral-targeted TNAP (AAV8-TNAP-D10). Here, we conducted dosing studies in both HPP mouse models. A single escalating dose from 4x108 up to 4x1010 (vg/b) was intramuscularly injected into 4-day-old Alpl-/- mice (an infantile HPP model) and a single dose from 4x106 up to 4x109 (vg/b) was administered to 8-week-old AlplPrx1/Prx1 mice (a late-onset HPP model). Wild-type littermates were used as controls. Serum alkaline phosphatase activity was increased, and PPi levels were decreased in a dose-dependent manner in both the Alpl-/- and AlplPrx1/Prx1 models. Radiographic and μCT analysis of long bones of female and male Alpl-/- mice showed full correction of skeletal phenotype at 4x1010 vg/b. We observed full correction of the bone phenotype at 4x108 and 4x109 in female AlplPrx1/Prx1 mice, but bones remained hypomineralized with the 4x106 and 4x107 (vg/b) doses after 70days of treatment. We observed skeletal improvements using the 4x109 (vg/b) dose, but the phenotype was not fully corrected in male AlplPrx1/Prx1. Immunohistochemistry using anti-TNAP and anti-D10 antibodies showed high immunolocalization in the femurs of female AlplPrx1/Prx1 mice, while D10 immunolocalization was high in the liver of male AlplPrx1/Prx1 mice at a dose of 4x109 (vg/b). This sex-dependent difference was not seen in the infantile HPP model. A serum proteome analysis showed enhanced inflammatory pathways in treated AlplPrx1/Prx1 males compared to treated female mice. We also found a few areas of ectopic calcification in soft organs at the highest tested dose of 4x1010 (vg/b) in Alpl-/- or 4x109 (vg/b) in the AlplPrx1/Prx1 model. This pre-clinical study will inform the design of clinical trials to develop gene therapy in early-onset and late-onset HPP patients.

CFTR mutation is associated with bone differentiation abnormalities in cystic fibrosis.

Cystic Fibrosis-related Bone Disease is an emerging challenge faced by 50 % of adult people with cystic fibrosis (CF). The multifactorial causes of this comorbidity remain elusive. However, congenital bone defects have been observed in animal models with CFTR mutations, suggesting its importance. The role of CFTR in bone cells development is unknown. Studies from human cells remain somewhat controversial depending on the cells used and the disease state of the patients from which the cells derived. Therefore, we investigated the role of CFTR in osteoblast development using induced pluripotent stem cells generated from homozygous CF donors for F508del and non-CF controls. This approach allows for a clear understanding towards how the CFTR mutation may influence osteoblast differentiation independently from other confounding factors. We observed a lower capacity of differentiation in CF cells as compared to control, already from mesenchymal stem cells (MSC) stage, whereby they retained expression of the pluripotency marker OCT4. Furthermore, our results demonstrated a delayed osteoblast commitment and altered expression of specific markers, such as an increased RANKL/OPG ratio and decreased BMP2, suggesting a potentially perturbed bone homeostasis associated with CFTR mutation. This is the first study of its kind, clearly demonstrating a role for CFTR mutation in delaying osteoblast differentiation and/or regeneration.

Fraxin inhibits ovariectomized-induced bone loss and osteoclastogenesis by suppressing ROS activity.

Osteoporosis is characterized by increased osteoclast activity, which is strongly associated with increased levels of reactive oxygen species (ROS). Fraxin, a natural coumarin glycoside, has shown anti-inflammatory and antioxidant properties, but its effects on bone homeostasis are obscure. The effects of fraxin on osteoclast formation and activation were measured via an in vitro osteoclastogenesis assay. Mitochondrial and total ROS production were evaluated with the aid of MitoSOX Red and DCFH-DA, respectively. Osteoclast-related gene expression analysis was performed via qPCR. Key proteins related to osteoclast formation, ROS scavenging, and ROS-regulated signaling, such as mitogen-activated protein kinases (MAPKs), NF-κB pathways, and nuclear factor of activated T cells 1 (NFATc1) signaling, were detected via western blotting. An ovariectomized mouse model was used to evaluate the therapeutic effects of fraxin in vivo. Fraxin inhibited osteoclastogenesis and osteoclast-related gene expression. Mechanistically, fraxin restored the levels of ROS-scavenging enzymes to inhibit ROS accumulation, eventually downregulating ROS-regulated signaling. The measurement of Micro-CT and histological analyses revealed that fraxin treatment significantly reduced OVX-induced bone loss by decreasing the number of osteoclasts. Fraxin shows promise as a novel therapeutic agent for osteoclast-related bone diseases, especially osteoporosis.

Dectin-2 depletion alleviates osteoclast-induced bone loss in periodontitis via Syk/NOX2/ROS signaling.

Periodontitis is the sixth most common disease worldwide and is closely associated with various systemic diseases, impacting overall health. It is characterized by the over-differentiation and activity of osteoclasts, leading to increased bone resorption and subsequent bone loss. Current treatments for bone loss are not ideal, highlighting the need for new targeted therapeutic strategies. Dectin-2, a member of the C-type lectin receptor (CLR) family, has recently been reported to play an important role in immune regulation, but its role in osteoclastogenesis has not been documented. This study identified a significant upregulation of Dectin-2 expression during osteoclast differentiation through single-cell sequencing and transcriptomic analysis. Knocking down Dectin-2 significantly inhibits the differentiation of RAW264.7 cells and bone marrow-derived macrophages (BMDMs) into osteoclasts, while overexpressing Dectin-2 enhances osteoclast differentiation and function. Mechanistically, transcriptomic analysis indicates that Dectin-2 deficiency disrupts redox homeostasis and affects the MAPK signaling pathway. Furthermore, the study demonstrates that Dectin-2 promotes osteoclastogenesis via the Syk/NOX2/ROS/MAPK signaling axis. In vivo, Dectin-2 knockout mice show reduced osteoclast numbers and decreased alveolar bone resorption in a periodontitis model. In conclusion, these findings suggest that Dectin-2 is a key regulatory factor in osteoclast-mediated bone resorption and may serve as a promising therapeutic target for bone diseases characterized by osteoclast overactivity, such as periodontitis.

Functional Hydrogel Interfaces for Cartilage and Bone Regeneration.

Effective treatment of bone diseases is quite tricky due to the unique nature of bone tissue and the complexity of the bone repair process. In combination with biological materials, cells and biological factors can provide a highly effective and safe treatment strategy for bone repair and regeneration, especially based on these multifunctional hydrogel interface materials. However, itis still a challenge to formulate hydrogel materials with fascinating properties (e.g., biological activity, controllable biodegradability, mechanical strength, excellent cell/tissue adhesion, and controllable release properties) for their clinical applications in complex bone repair processes. In this review, we will highlight recent advances in developing functional interface hydrogels. We then discuss the barriers to producing of functional hydrogel materials without sacrificing their inherent properties, and potential applications in cartilage and bone repair are discussed. Multifunctional hydrogel interface materials can serve as a fundamental building block for bone tissue engineering.

Investigating the Molecular Mechanisms of Jiangu Decoction in Treating Type 2 Diabetic Osteoporosis.

Type 2 diabetic osteoporosis (T2DOP) is a metabolic bone disease characterized by impaired bone structure and decreased bone strength in diabetic patients. Jiangu Decoction (JGD), a traditional Chinese poly-herbal formulation, has shown efficacy in mitigating osteoporosis (OP) and fractures caused by osteoporosis in diabetic patients in clinical trials. In addition, JGD has been proven to promote the proliferation of osteoblasts. However, the specific mechanisms underlying these effects remain unclear. This study aimed to elucidate the molecular mechanisms underlying the therapeutic effects of JGD in treating T2DOP. Liquid chromatography-mass spectrometry (LC-MS) was utilized to elucidate the chemical profile of JGD. A T2DOP mouse model (C57BL/6) was established by combining a high-fat diet with streptozotocin (STZ). Micro-computed tomography (micro-CT) imaging, three-point bending tests, and histological staining were utilized to assess alterations in bone mass, bone quality, and bone strength in mice. Mouse Calvaria 3T3-E1 (MC3T3-E1) cells were treated with 33 mmol/L D-glucose (HG), and the protective effect of JGD on the high glucose injury model was observed. Western blotting and qRT-PCR were employed to analyze alterations in biomarkers associated with the Keap1/Nrf2/HO-1 signaling pathway, both in vivo and in vitro. A total of 909 compounds were identified in JGD using LC-MS. Subsequently, the function of JGD was evaluated both in vitro and in vivo. The findings indicated that JGD promoted bone formation, enhanced bone microstructure, and ameliorated diabetic symptoms in T2DOP mice. Additionally, JGD increased alkaline phosphatase (ALP) activity, facilitated bone mineralization, and upregulated the expression levels of osteogenic marker genes such as runt-related transcription factor 2 (Runx2), osteocalcin (Ocn), and collagen type 1 alpha (Col1a1). Importantly, JGD reduced oxidative stress levels and decreased the accumulation of reactive oxygen species by modulating the Keap1/Nrf2/HO-1 axis both in vivo and in vitro. Our study suggests that JGD could alleviate T2DOP impairment, closely linked to the Keap1/Nrf2/HO-1 signaling pathway.

Enhanced Osteoporosis Treatment via Nano Drug Coating Encapsulating Lactobacillus rhamnosus GG.

Osteoporosis is the most common systemic skeletal disorder, particularly associated with aging and postmenopausal women. With the growing knowledge about the gut-bone axis, the therapeutic strategies for osteoporosis have been shifted toward regulating gut microbiota to promote positive bone metabolism. AlthoughLactobacillus rhamnosus GG (LGG) is widely reported to positively regulate bone metabolism by restoring the dysbiotic microbiome, oral administration is associated with sensitivity to gastric fluid and low bioavailability. Other studies also demonstrated that bisphosphonates ameliorate osteoporosis by directly regulating bone metabolism, especially inhibiting osteoclast activity. However, the side effects caused by bisphosphonate treatment still represent a significant problem. In this study, we assembled alendronate, a clinically used bisphosphonate, with DSPE-phospholipid nanoencapsulation and LGG (ADB), to protect LGG from the acidic environment of the stomach, while simultaneously reducing the gastrointestinal side effects associated with the oral administration of alendronate. We further investigated the potential of these DSPE-phospholipid nanoencapsulated bacteria ADB to repair osteoporotic bone deterioration, and their ability to regulate gut microbiota in vivo, which is strongly associated with the intrinsic environment. Compared with the same dosage of LGG and alendronate alone, ADB positively regulated bone metabolism, and osteoporosis was significantly revised in ovariectomized mice models.

Clinically Deployable Electro-Immunosensing Device Comprising Bioactive Glass-MWCNT for Alkaline Phosphatase Detection in Human Serum Samples.

Bone is a dynamic tissue that serves several purposes in the human body, including storing calcium, forming blood cells, and protecting and supporting the body's organs. Alkaline phosphatase (ALP) is secreted into the circulation by osteoblasts, the cells responsible for making bone. It attaches to the surface of osteoblast cells or matrix vesicles. Accordingly, ALP is present in serum and is a popular biomarker for the evaluation of bone disease and other disorders in clinical evaluations. In this study, a composite probe made of bioactive glass (BG) and multiwalled carbon nanotubes (MWCNT) was used to detect ALP through electrochemical impedance spectroscopy (EIS) without the need for labels. By combination of physical methods with electrochemical analysis, the biosensor probe was characterized. The analytical performance of the biosensor was evaluated using EIS, and the results revealed that it has a limit of detection (LOD) of 2.29 ± 0.35 U/L and a linear dynamic range (LDR) of 25-600 U/L; both of which are within the acceptable range for ALP detection in clinics. When tested against serum interfering chemicals, the biosensor probe that was designed shows a strong selectivity for ALP (Ksel < 0.06). In addition, human serum and fetal bovine serum were used to test the system's ability to detect ALP in biological samples.

Administration of Bisphosphonate Preparations to Mice with Mild-type Hypophosphatasia Reduces the Quality of Spontaneous Locomotor Activity

Hypophosphatasia (HPP) is a congenital bone disease caused by tissue-nonspecific mutations in the alkaline phosphatase gene. It is classified into six types: severe perinatal, benign prenatal, infantile, pediatric, adult, and odonto. HPP with femoral hypoplasia on fetal ultrasonography, seizures, or early loss of primary teeth can be easily diagnosed. In contrast, pediatric, adult, and odonto types of HPP over 4 years of age are less likely to be diagnosed because they do not have typical symptoms. Consequently, it may be misdiagnosed as common osteoporosis, and treatments incompatible with HPP may be implemented. The purpose of this study was to analyze the effects of bisphosphonate preparations administration on the femur of Akp2+/− mice, a mild-type HPP mice model. Zoledronic acid (Zol) was subcutaneously administered to 4-week-old Akp2+/− mice at 1 mg/kg (volume: 200 μL) once a week for a total of 5 times. Afterward, spontaneous locomotor activity analysis was performed, and serum and femur bones were collected at 9 weeks of age. Additionally, micro-computed tomography (CT) analysis, histological analysis, and analysis of the expression levels of various marker proteins and genes were performed. Age-matched Akp2+/+ mice served as controls. The results demonstrated that the administration of Zol to Akp2+/− mice, compared to Akp2+/+ mice, insufficiently promotive bone formation, torn femoral head cartilage, and decreased spontaneous locomotor activity. Therefore, it is important to accurately diagnose patients with mild-type HPP.

Signaling Dynamics in Osteogenesis: Unraveling Therapeutic Targets for Bone Generation.

Diseases affecting bone encompass a spectrum of disorders, from prevalent conditions such as osteoporosis and Paget's disease, collectively impacting millions, to rare genetic disorders including Fibrodysplasia Ossificans Progressiva (FOP). While several classes of drugs, such as bisphosphonates, synthetic hormones, and antibodies, are utilized in the treatment of bone diseases, their efficacy is often curtailed by issues of tolerability and high incidence of adverse effects. Developing therapeutic agents for bone diseases is hampered by the fact that numerous pathways regulating bone metabolism also perform pivotal functions in other organ systems. Consequently, the selection of an appropriate target is a complicated process despite the significant demand for novel medications to address bone diseases. Research has shown the role of various cell signaling pathways, including Wnt, PTHR1, CASR, BMPRs, OSCAR, and TWIST1, in the regulation of osteogenesis, bone remodeling, and homeostasis. Disruptions in bone homeostasis can result in decreased bone density and the onset of osteoporosis. There remains a need for the development of drugs that can enhance bone remodeling with improved side effects profiles. The exploration of promising targets to stimulate bone formation has the potential to significantly advance the field of bone-related medical care, thereby improving the quality of life for millions. Additionally, a deeper understanding of anabolic and catabolic pathway mechanisms could enable future studies to explore synergistic effects between unrelated pathways. Herein, we explore potential drug targets that may be exploited therapeutically using small molecule agonists or antagonists to promote bone remodeling and discuss their advantages and limitations.