Accelerated Development With Increased Bone Mass and Skeletal Response to Loading Suggest Receptor Activity Modifying Protein-3 as a Bone Anabolic Target

Knockout technologies provide insights into physiological roles of genes. Studies initiated into endocrinology of heteromeric G protein-coupled receptors included deletion of receptor activity modifying protein-3, an accessory protein that alters ligand selectivity of calcitonin and calcitonin-like receptors. Initially, deletion of Ramp3-/- appeared phenotypically silent, but it has emerged that mice have a high bone mass phenotype, and more subtle alterations to angiogenesis, amylin homeostasis, and a small proportion of the effects of adrenomedullin on cardiovascular and lymphatic systems. Here we explore in detail, effects of Ramp3-/- deletion on skeletal growth/development, bone mass and response of bone to mechanical loading mimicking exercise. Mouse pups lacking RAMP3 are healthy and viable, having accelerated development of the skeleton as assessed by degree of mineralisation of specific bones, and by microCT measurements. Specifically, we observed that neonates and young mice have increased bone volume and mineralisation in hindlimbs and vertebrae and increased thickness of bone trabeculae. These changes are associated with increased osteoblast numbers and bone apposition rate in Ramp3-/- mice, and increased cell proliferation in epiphyseal growth plates. Effects persist for some weeks after birth, but differences in gross bone mass between RAMP3 and WT mice lose significance in older animals although architectural differences persist. Responses of bones of 17-week old mice to mechanical loading that mimics effects of vigorous exercise is increased significantly in Ramp3-/- mice by 30% compared with WT control mice. Studies on cultured osteoblasts from Ramp3-/- mice indicate interactions between mRNA expression of RAMPs1 and 3, but not RAMP2 and 3. Our preliminary data shows that Ramp3-/- osteoblasts had increased expression β-catenin, a component of the canonical Wnt signalling pathway known to regulate skeletal homeostasis and mechanosensitivity. Given interactions of RAMPs with both calcitonin and calcitonin-like receptors to alter ligand selectivity, and with other GPCRs to change trafficking or ligand bias, it is not clear whether the bone phenotype of Ramp3-/- mice is due to alterations in signalling mediated by one or more GPCRS. However, as antagonists of RAMP-interacting receptors are growing in availability, there appears the likelihood that manipulation of the RAMP3 signalling system could provide anabolic effects therapeutically.

Comparative characteristics of changes in subchondral bone of rats after antenatal glucocorticoid administration and modeling of osteoporosis

Background. Osteoporosis is a progressive systemic bone disease that results in decreased bone mineral density and, as a result, increases the risk of bone fractures. Changes that occur in the subchondral bone in osteoporosis or because of hormones can cause degenerative changes in the articular cartilage that underlie osteoarthritis. Objective. The aim of the study was to identify and compare morphological changes that occur in the subchondral bone in experimental simulations of osteoporosis and in adult rats that were born from females that were exposed to glucocorticoid solution administration in the 3rd trimester of pregnancy. Methods. Tibias of 26 white mature laboratory rats were studied. In serial sections, the relative areas occupied by bone trabeculae and lacunae were calculated. Results. The relative area involving the bone trabeculae (23,2 ± 3,70%) statistically significantly decreased at 21 day in the group of animals that undergone a simulation of osteoporosis in comparison with the control group. Similar changes are observed in the group of experimental animals that were born from females that were exposed to glucocorticoid solution administration in the 3rd trimester of pregnancy. Conclusion. Thus, the results of the study demonstrate the similarity of morphological changes occurring in the subchondral bone in rats that undergone a simulation of osteoporosis and rats that were born from females that were exposed to glucocorticoid solution administration in the 3rd trimester of pregnancy.

Benefits and Mechanisms of Exercise Training for Knee Osteoarthritis

Knee osteoarthritis is a chronic degenerative disease. Cartilage and subchondral bone degeneration, as well as synovitis, are the main pathological changes associated with knee osteoarthritis. Mechanical overload, inflammation, metabolic factors, hormonal changes, and aging play a vital role in aggravating the progression of knee osteoarthritis. The main treatments for knee osteoarthritis include pharmacotherapy, physiotherapy, and surgery. However, pharmacotherapy has many side effects, and surgery is only suitable for patients with end-stage knee osteoarthritis. Exercise training, as a complementary and adjunctive physiotherapy, can prevent cartilage degeneration, inhibit inflammation, and prevent loss of the subchondral bone and metaphyseal bone trabeculae. Increasing evidence indicates that exercise training can improve pain, stiffness, joint dysfunction, and muscle weakness in patients with knee osteoarthritis. There are several exercise trainings options for the treatment of knee osteoarthritis, including aerobic exercise, strength training, neuromuscular exercise, balance training, proprioception training, aquatic exercise, and traditional exercise. For Knee osteoarthritis (KOA) experimental animals, those exercise trainings can reduce inflammation, delay cartilage and bone degeneration, change tendon, and muscle structure. In this review, we summarize the main symptoms of knee osteoarthritis, the mechanisms of exercise training, and the therapeutic effects of different exercise training methods on patients with knee osteoarthritis. We hope this review will allow patients in different situations to receive appropriate exercise therapy for knee osteoarthritis, and provide a reference for further research and clinical application of exercise training for knee osteoarthritis.

Morphological and radiological characteristics of experimental bone tissue regeneration

Objective. To study the dynamics of reparative bone tissue regeneration in experimental animals using a native transplantation autosmix (NTA).Materials and methods. Male Wistar rats weighing 180–200 g and aged 6–7 months were used. Bone tissue defects were modelled using a cutter with a diameter of 2 mm (experimental group). A similar defect of the middle third of the right tibia was formed in the control group animals without flling the defects with bone tissue. The animals were removed from the experiment on days 3, 7, 14, 30 and 60 of the experiment (per 6 animals for each observation period). The indicators of defect occupancy, necrosis, the area of bone trabeculae, the area of granulation tissue were determined in the histological sections. All the indicators were presented as percentage of the tested area. Osteoblasts, osteocytes, and osteoclasts were calculated in absolute values on the tested area.Results. The study has showed a higher rate of bone tissue formation in the bone defects in the experimental animals after autotransplantation of the bone mixture. Bone recovery in the experimental group had a higher rate, which was manifested by faster flling of the bone tissue defect, a low percentage of the necrosis area, a higher area of bone trabeculae, its rapid transformation into lamellar bone tissue.Conclusion. Osteogenesis had practically completed by day 30 of the experiment. At the same time, in the control group it had completed by day 60. The results obtained are a theoretical precondition for further research in the feld of bone autoplasty. Advanced development of surgical and minimally invasive technologies of bone mixture application will increase the effciency of modern reconstructive surgery of bones and joints.

PRECISION ASSESSMENT OF THE STATE OF BONE TRABECULAE AND MINERAL SATURATION OF BONE SPONGY STRUCTURES IN WORKERS EXPOSED TO CONTACT ULTRASOUND

A comparative retrospective analysis of the results of a clinical - X-ray examination of 93 women doctors of ultrasound examinations of working age and 60 people was performed. control groups of age and experience comparable work with persons of major groups (nurses not associated with exposure to occupational ultrasound). Degenerative-dystrophic changes were revealed in the form of: osteorthrosis of the shoulder, elbow, wrist and interphalangeal joints, periarthrosis of the shoulder and elbow joints, small cyst-like clearances and enostoses in the bones of the wrists of the most loaded upper limb. The level of decrease in the mineral saturation and thickness of bone trabeculae in the areas of interest of the radius bones and distal phalanges of the hands was dependent on the severity of the clinical picture of vegetative-sensory polyneuropathy. Indicators of bone density and the state of bone trabeculae in the spongy structures of the distal radial bones and distal phalanges can be a kind of marker of the severity of OP. The use of modern methods for assessing the density and structure of bone tissue allows us to reduce the negative role of the so-called "human factor" and thus

Exosomal miR-100-5p inhibits osteogenesis of hBMSCs and angiogenesis of HUVECs by suppressing the BMPR2/Smad1/5/9 signalling pathway

Background Nontraumatic osteonecrosis of the femoral head (NONFH) is a common, progressive, and refractory orthopaedic disease. Decreased osteogenesis and angiogenesis are considered the main factors in the pathogenesis of NONFH. We aimed to figure out whether exosomes and exosomal miRNA from necrotic bone tissues of patients with NONFH are involved in the pathogenesis of NONFH and reveal the underlying mechanisms. Methods RT-PCR and western blotting (WB) were used to detect the expression of osteogenic, adipogenic, and angiogenic markers. ALP staining and Alizarin Red S (ARS) staining were used to evaluate osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs). Oil Red O staining was performed to assess the adipocyte deposition. A tube formation assay was used to study angiogenesis of human umbilical vascular endothelial cells (HUVECs). H&E staining and immunohistochemistry (IHC) staining were used to detect the effect of the NONFH exosomes in vivo. MicroRNA sequencing was conducted to identify potential regulators in the NONFH exosomes. The target relationship between miR-100-5p and BMPR2 was predicted and confirmed by a dual luciferase reporter assay and WB. Results The NONFH exosomes reduced the osteogenic differentiation of hBMSCs and angiogenesis of HUVECs. In addition, the injection of the NONFH exosomes caused thinning and disruption of bone trabeculae in the femoral heads of rats. MiR-100-5p expression was upregulated in the NONFH exosomes and inhibited the osteogenesis of hBMSCs and angiogenesis of HUVECs by targeting BMPR2 and suppressing the BMPR2/SMAD1/5/9 signalling pathway. Silencing miR-100-5p expression rescued the reduction in osteogenesis and angiogenesis caused by the NONFH exosomes by activating the BMPR2/SMAD1/5/9 signalling pathway. Conclusion The NONFH exosomal miR-100-5p can lead to NONFH-like damage by targeting BMPR2 and suppressing the BMPR2/SMAD1/5/9 signalling pathway, which may be involved in the pathophysiological mechanisms of nontraumatic osteonecrosis of the femoral head (NONFH).

Anti-osteoporosis effect of Notopterygium incisum Ting ex H. T. Chang extract in rats

Purpose: To investigate the effect of Notopterygium incisum Ting ex H.T. Chang extract (NICE) on ovariectomy-induced osteoporosis in rats. Methods: Female Sprague-Dawley rats were randomly assigned to a normal group (control) and five ovariectomy (OVX) subgroups: OVX with vehicle (OVX), OVX with positive control drug alendronate sodium tablets (1.8 mg/kg/week), and OVX with varying NICE doses (45, 90, or 180 mg/kg/day). After rats were subjected to ovariectomy for 4 weeks, alendronate or NICE were administered orally daily for 16 weeks. The bone mineral density (BMD) of the L4 vertebrae and right femurs of all rats was estimated. The serum hormones estradiol (E2), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels and serum alkaline phosphatase (ALP), osteocalcin (OC) and telopeptides of collagen type I (CTx) levels of rats were detrmined. Results: The results show that NICE dose-dependently inhibited bone mineral density (BMD) reduction of L4 vertebrae and femurs (p < 0.05). Compared with OVX group, serum E2, FSH and LH levels was significantly increased in osteoporosis rats (p < 0.01), but serum ALP, CTx, and OC concentrations were significantly lower (p < 0.05). On the other hand, bone trabeculae in the three NICE groups and nilestriol group were all wider, while the space and connections increased. Conclusion: These findings indicate that NICE mitigates OVX-induced osteoporosis in rats, and hence can potentially be developed for the management of osteoporosis.

Rickets in a Thoroughbred-cross foal: case report and review of the literature

Rickets is a metabolic bone disease associated with failure of endochondral ossification and impaired osteoid mineralization in growing animals. As a consequence, affected individuals can develop gross and microscopic bone malformations. The most common causes of rickets in domestic species include vitamin D and phosphorus deficiency. Rickets has been described in multiple species; however, comprehensive postmortem characterizations with confirmatory histopathology in equids have not been published. A 6-mo-old, Thoroughbred-cross foal was diagnosed with rickets based on gross autopsy findings and microscopic examination of the ribs and long bones. Grossly, all costochondral junctions of the ribs were enlarged with a “rachitic rosary” appearance, and there were multiple fracture calluses in the rib bodies. Epiphyses and metaphyses of the long bones appeared widened on sagittal section, and their physes were irregularly thickened. Histologically, there were poorly organized columns of hypertrophic chondrocytes within the physes of affected bones, islands of chondrocytes embedded within the primary and secondary spongiosa, and faintly eosinophilic seams of poorly mineralized osteoid within the bone trabeculae. Areas of focally increased osteoclastic activity were observed in some of the sections, perhaps pointing to a more complex metabolic bone disease in a growing animal. Low serum concentrations of calcium and 25-hydroxyvitamin D were detected in an antemortem sample. The pathogenesis of these imbalances was not definitively established, but lack of sunlight exposure, low concentration of vitamin D precursors in the diet (perhaps secondary to malnutrition), or both, were suspected; a genetic basis cannot be ruled out.

Effect of implants of hydroxyapatite with tricalcium phosphates alloyed with Si on histomorphological and biochemical parameters in cases of bone defects of rabbits

Complex comminuted fractures are accompanied by development of bone defects and loss of reparative potential of the bone tissue in the region of the trauma. This brings the necessity of using implants with optimum osteoconductive and osteointegration properties. The objective of the study was determining the condition of biochemical bone markers and peculiarities of histomorphological changes under the influence of ceramic hydroxyapatite (HA) implants with various physical-chemical properties in the conditions of diaphyseal bone defects in rabbits. We composed control and experimental groups of rabbits with 10 individuals in each with diaphyseal bone defects (3 mm) of the radial bones formed under general anesthesia. In one experimental group, they were filled with granules of hydroxyapatite with α-tricalcium phosphate, and in the second group – with β-tricalcium phosphate, alloyed with Si. In the control rabbits, the defects healed under a blood clot. Blood was analyzed on the 3rd, 7th, 14th, 21st and 42nd days, and as reference we used biochemical parameters of blood of clinically healthy rabbits (n = 10). Bone biopsied materials were taken on days 21–42 under general anesthesia. When using hydroxyapatite with β-tricalcium phosphate, alloyed with Si, we determined early intensification of the levels of nitrogen oxide, angiogenesis and development of bone regenerate in conditions of shortening of inflammatory resorption phase, which was verified according to the level of tartrate-resistant acid phosphatase. According to the level of bone isoenzyme of alkaline phosphatase in the blood serum of animals of the control group, the reparative osteogenesis developed slowly and peaked on day 42, whereas in animals implanted with α-tricalcium phosphate, its development peaked peaked on days 14–42, and when using Si-alloy – on days 7–14. Histomorphologically, on the 21st day, in the case of replacement of bone defect with hydroxyapatite with α-tricalcium phosphate, coarse-fibered type of bone regenerate developed with no dense contact with the elements of the regenerate, while spongy bone trabeculae occurred when hydroxyapatite was applied with β-tricalcium phosphate alloyed with Si, and the control rabbits were observed to be in the stage of cartilaginous callus. On the 42nd day, under the influence of implants of hydroxyapatite with α-tricalcium phosphate, the spongy bone tissue transformed into compact tissue with further mineralization. With implants alloyed with Si, there occurred compact bone tissue, and bone regenerates of the control animals were regions of coarse-fibered and spongy bone tissue without dense contact with the parent bone. This study revealed that hydroxyapatite with β-tricalcium phosphate alloyed with Si had notable osteoinductive and osteointegrating properties, as indicated by early angiogenesis and osteoblast reaction, positive dynamics of the marker biochemical parameters with faster and better development of bone regenerate as spongy bone trabeculae.

Osteitis fibrosa cystica mimicking bone tumor, a case report

Background We report a case of osteitis fibrosa cystica, a rare benign resorptive bone lesion caused by hyperparathyroidism, that presented on imaging as an aggressive bone tumor. Case presentation The patient is a 51-year-old male complaining of severe sustained pain of the right hip region. Imaging studies were suspicious for a malignant tumor of the right iliac bone. Biopsy under CT guidance was performed and showed remodeled bone trabeculae with numerous osteoclasts, excluding bone tumor and raising the possibility of osteitis fibrosa cystica. Complementary tests disclosed elevated blood level of parathyroid hormone and a partially cystic enlarged left inferior parathyroid gland consistent with adenoma. After parathyroidectomy, the clinical symptoms were relieved and the radiological findings were significantly improved, which confirmed the diagnosis. Conclusions Metabolic diseases-associated bone lesions should always be considered in the differential diagnosis of bone tumors, to avoid unnecessary surgeries and treatments.