Excessive Bone Formation Research Articles

Dual cross-linked polyurethane-alginate biomimetic hydrogel for elastic gradient simulation in osteochondral structures: Microenvironment modulation and tissue regeneration

The distinctive composition and functions of osteochondral structures result in constrained regeneration. Insufficient healing processes may precipitate the emergence of tissue growth disorders or excessive subchondral bone formation, which can culminate in the deterioration and failure of osteochondral tissue repair. To overcome these limitations, materials designed for osteochondral repair must provide region-specific modulation of the microenvironment and mechanical compatibility. To address these challenges, we propose a method to create continuous hydrogels with distinct structural and functional properties by a precise cross-linking method. We have developed an innovative polyurethane enriched with dimethylglyoxime, facilitating the coordinated loading and precise release of Zn2+. This strategy enables the meticulous control of alginate cross-linking, resulting in an elastic gradient hydrogel that closely resembles the osteochondral interface. The SeSe within the hydrogel effectively modulates the inflammatory microenvironment and fosters the M2 polarization of macrophages. The hydrogel's lower layer is designed to rapidly release Zn2+, thereby enhancing bone regeneration. The upper layer is intended to prevent bone overgrowth and stimulate chondrogenic differentiation. This dual-layer strategy allows targeted stimuli to each region, promoting the seamless integration of neoosteochondral tissue. Our study demonstrates the potential of this stratified hydrogel in achieving uniform and smooth osteochondral tissue regeneration.

Computed tomographic characteristics of craniomandibular osteopathy in 20 dogs.

Craniomandibular osteopathy (CMO) is a proliferative, self-limiting, non-neoplastic disease of growing dogs characterised by excessive new bone formation on the skull and mandible. The radiographic findings of CMO are well described; however, limited reports of the computed tomographic (CT) appearance are available. This paper aims to characterise the spectrum of CT findings that can occur with CMO. The study is retrospective, descriptive, multicenter, and includes 20 cases. Age at presentation ranged from 6 weeks to 12 months, with no sex predisposition. Scottish terriers were overrepresented (65%); other breeds included Cairn terrier, Jack Russell terrier, Staffordshire bull terrier, labrador retriever, golden retriever, akita and Slovakian rough-haired pointer (one of each breed). Terrier breeds represented 80% (16/20) of the patient cohort. Mandibular osteoproliferation was present in all patients (marked in 80%, bilateral in 95%), affecting the rostral mandible in 25%, body in 85%, and ramus in 80%. Tympanic bulla osteoproliferation was present in 60% (12/20) of patients (all marked, bilateral in 75%). Cranial osteoproliferation (frontal, parietal, temporal, occipital bones or maxilla, or combinations of them) was present in 90% (18/20) of patients (40% marked, 27% moderate, 33% mild). Nasopharyngeal narrowing was seen in all 12 patients with tympanic bulla osteoproliferation (67% marked, 27% moderate) and caused nearly complete occlusion in two of them. External ear canal stenosis was seen in 55% (11/20) of patients (63% marked, 37% moderate, all bilateral). Temporomandibular joint (TMJ) impingement was suspected in 83% (10/12) of patients with marked tympanic bulla osteoproliferation (75% bilateral). Osteolysis with a moth-eaten pattern was seen in the mandible of 10/20 dogs, the calvarium of 5/20 dogs, and the maxilla of 1/20 dogs (5%). Lymphadenomegaly (mandibular and medial retropharyngeal) was found in 15/20 patients (70% mild, 30% moderate). The most severe CT changes were seen in Scottish terriers. CT allows for detailed characterisation of the bony changes associated with CMO, including the effects occurring secondary to osteoproliferation surrounding the tympanic bullae such as TMJ impingement, external ear canal stenosis, and nasopharyngeal narrowing. Osteoproliferation affecting the cranium and the presence of osteolysis were seen more frequently in this study than previously reported in CMO.

POLYCYSTIC OVARY SYNDROME AND BONE TURNOVER IN POSTMENOPAUSAL WOMEN

Considering the metabolic and hormonal changes associated with polycystic ovary syndrome (PCOS), their potential affect bone health has been proposed. The aim of the current study was to evaluate the effect of several hormonal and metabolic alterations associated with polycystic ovary syndrome on bone in postmenopausal women. Materials and methods: The study included 56 patients with PCOS and 42 women without this disease aged 50–65 years. Dual-energy X-ray absorptiometry was used to measure bone mineral density (BMD) of the lumbar spine and femoral neck. Serum levels of amino-terminal propeptide of procollagen 1 (P1NP) and carboxy-terminal telopeptide of type I collagen (b-CTx), as well as levels of parathyroid hormone (PTH), vitamin D (25(OH)D3), anti-Mullerian hormone (AMH), insulin, testosterone (T), 17-hydroxyprogesterone (17-OHP), dehydroepiandrostenedione sulfate (DHEAS), follicle stimulating hormone, luteinizing hormone, and estradiol were determined. The HOMA-IR index and anthropometric indicators were calculated. Statistical data were analyzed by nonparametric testing using BioStat Pro 6.2.2.0 software (AnalystSoft Inc., Walnut, USA). Quantitative data are presented as median and quartiles 1 and 3 (Me [Q1; Q3]); The significance of intergroup differences was established using the Mann–Whitney U test (p<0.05). To identify relationships between indicators, a univariate analysis was carried out with the calculation of the Spearman rank correlation coefficient (r). Results. Women with PCOS had late-onset menopause (p=0.007) and a higher body mass index (BMI, p=0.009) than the control group. Additionally, women with PCOS had higher levels of DHEAS, total T, and 17-OHP than controls. P1NP and b-CTx were significantly different from controls (p=0.028 and p=0.032, respectively). A direct relationship was found between BMI and the activity of the resorption marker b-CTx (r=0.342, p=0.002) and an inverse collinear relationship between AMH values with b-CTx (r=–0.507, p=0.001). BMD in PCOS was higher compared to controls. An inverse relationship exists between BMD of L1–L4 and b-CTx level (r=–0.387, p=0.026) and positive with insulin (r=0.267, p=0.042), AMH (r=0.561, p=0.031) and testosterone (r=0.458, p=0.039). Higher DHEAS levels were associated with higher femoral neck BMD (r=0.473, p=0.035). P1NP was negatively correlated with femoral neck BMD (r=-0.429, p=0.038). Conclusions. Bone mineral density in women with polycystic ovary syndrome declines more slowly with age compared to their peers, possibly due to the effects of excess androgens and insulin. In postmenopausal women with polycystic ovary syndrome, metabolic processes in bone tissue accelerate, while bone resorption exceeds bone formation. Thus, women affected by polycystic ovary syndrome may be considered at risk of developing osteopenic syndrome.

Phillyrin: A potential therapeutic agent for osteoarthritis via modulation of NF-κB and Nrf2 signaling pathways

Osteoarthritis (OA) is the predominant cause of disability among elderly people worldwide and is characterized by cartilage degeneration and excessive bone formation. Phillyrin, derived from forsythia, is a key extract renowned for its pronounced antibacterial and anti-inflammatory effects. Forsythia, deeply integrated into traditional Oriental medicine, has historically been utilized for its various pharmacological effects, including antibacterial, anti-inflammatory, and hepato-protective properties. Nevertheless, the anti-inflammatory impact of phillyrin on the progression of osteoarthritis remains enigmatic. The objective of this research was to assess the anti-inflammatory and anti-aging properties of phillyrin in mouse chondrocytes induced by IL-1β, as well as to elucidate the fundamental mechanisms underlying the phenomenon at play. Additionally, the investigation extends to observing the impact of phillyrin by establishing a murine osteoarthritic model. The ultimate goal was to identify phillyrin as a potential antiosteoarthritic agent. This investigation employs a multifaceted approach. Initially, key action targets of phillyrin, along with its probable action pathways, were identified by molecular docking and network pharmacological techniques. These findings were subsequently confirmed through both in vivo and in vitro studies. Network pharmacological analysis revealed NFE2L2 (NRF2), NFKB1, TLR4, and SERPING1 as pivotal candidate targets for the treatment of osteoarthritis with phillyrin. Molecular docking revealed hydrogen bond interactions between phillyrin and Arg415, Arg483, Ser508, and Asn387 on the Nrf2 receptor, while electrostatic interactions occurred with residues Arg415 and Arg380. Experiments conducted in vitro indicated that phillyrin preconditioning hindered the IL-1β-induced expression of proinflammatory factors which included TNF-α, COX-2, IL-6, and iNOS. Furthermore, phillyrin counteracts the IL-1β-induced degradation of aggrecan and collagen II within the extracellular matrix (ECM). This protective action is caused by the inhibition of the NF-κB pathway by phillyrin. Additionally, the mitigation of chondrocyte aging by phillyrin was observed. Our investigation revealed that phillyrin mitigates inflammation and counteracts cartilage degeneration in osteoarthritis (OA) patients by suppressing inflammation in chondrocytes and impeding aging through suppression of the NF-κB pathway.

Mechanisms of Spinal Metastases: New Perspectives

Metastases are considered to be a key mechanism for the spread of malignant tumors, whereby tumor cells separate from the primary site and form new tumor nodes in various parts of the body. Bone tissue, including the spine, is often affected by metastases, which can significantly worsen the prognosis and quality of life of patients. Metastasis comprises a complex multistep process during which tumor cells undergo molecular and phenotypic changes enabling them to migrate and adapt to new conditions in the body. Bone metastases can be osteolytic, causing bone destruction, or osteoblastic, stimulating excessive bone formation. Tumor cells enter the bone and activate osteoclasts or osteoblasts, thereby leading to remodelling of bone tissue and formation of a closed cycle of bone destruction and tumor growth. The characteristics of tumor cells are determined by their genetic and epigenetic changes, as well as interaction with the environment. Understanding the molecular and pathophysiological aspects of spinal metastasis is essential to developing effective treatments and improving therapeutic approaches. The paper considers new therapeutic approaches aimed at overcoming spinal metastasis in order to improve the prognosis and quality of life of patients.

In Vitro Cell Culture Model for Osteoclast Activation during Estrogen Withdrawal.

Estrogen (17β-estradiol) deficiency post-menopause alters bone homeostasis whereby bone resorption by osteoclasts exceeds bone formation by osteoblasts, leading to osteoporosis in females. We established an in vitro model to examine the consequences of estrogen withdrawal (E2-WD) on osteoclasts derived from the mouse macrophage RAW 264.7 cell line and utilized it to investigate the mechanism behind the enhanced osteoclast activity post-menopause. We found that a greater population of osteoclasts that underwent E2-WD contained a podosome belt necessary for osteoclasts to adhere and resorb bone and possessed elevated resorptive activity compared to osteoclasts exposed to estrogen (E2) continuously. Our results show that compared to osteoclasts that received E2 continuously, those that underwent E2-WD had a faster rate of microtubule (MT) growth, reduced RhoA activation, and shorter podosome lifespan. Thus, altered podosome and MT dynamics induced by the withdrawal of estrogen supports podosome belt assembly/stability in osteoclasts, which may explain their enhanced bone resorption activity.

P178 CXCL12/CXCR4-mediated osteogenic precursor cells recruitment: a key mechanism in ankylosing spondylitis-associated pathological bone formation

Abstract Background/Aims Ankylosing spondylitis (AS) is a debilitating condition characterised by severe spinal deformities, inflammation, and excessive bone formation, imposing significant socioeconomic burdens. Current treatments alleviate symptoms but fail to address bone structural damage. Pathological bone formation often occurs at entheses, where tendons and ligaments connect to bone. Osteogenic precursor cells (OPCs) play a crucial role, but their migration to new bone sites is poorly understood. C-X-C motif chemokine ligand 12 (CXCL12) is implicated in cell migration and bone-related processes, but its role in AS remains unclear. This study explores CXCL12/CXCR4 signalling in OPC recruitment and new bone formation, providing insights into AS pathogenesis and potential therapeutic targets. Methods We established mouse models, including the DBA/1 model, lipopolysaccharide-induced spondyloarthritis model, and Achilles tendon semi-transection model to confirm the role of CXCL12-Induced OPCs migration in pathological new bone formation. Additionally, genetically edited mouse models were generated to confirm the underlying mechanism of OPCs migration and their spatiotemporal phenotypes of differentiation, including DBA1;CXCL12 col2 transgenic mice, CXCL12hi/hi;Col2a1-creERT mice, and CXCR4fl/fl;Prx1-creERT mice. Results In this study, we have identified CXCL12 as a crucial contributor to the initiation of pathological new bone formation by recruiting OPCs. CXCL12 was highly expressed in regions predisposed to pathological bone development, attracting OPCs to these upregulated areas. Inhibiting the CXCL12/CXCR4 axis with AMD3100 or the conditional knockout of CXCR4 effectively reduced OPC migration and subsequent pathological bone formation in animal models of AS. Overexpression of CXCL12 in genetically engineered animals with a DBA/1 background demonstrated a stable joint ankylosis phenotype, providing a valuable model for the study of AS. Furthermore, our research revealed the indispensable role of Rac1 in OPC migration and the ensuing pathological bone formation. Conclusion This study elucidates the novel role of CXCL12 in AS and offers potential strategies for targeting the CXCL12/CXCR4-Rac1 axis to prevent the progression of axial skeletal ankylosis. Disclosure H. Cui: None. H. Liu: None.

Toll-like receptor-2 induced inflammation causes local bone formation and activates canonical Wnt signaling.

It is well established that inflammatory processes in the vicinity of bone often induce osteoclast formation and bone resorption. Effects of inflammatory processes on bone formation are less studied. Therefore, we investigated the effect of locally induced inflammation on bone formation. Toll-like receptor (TLR) 2 agonists LPS from Porphyromonas gingivalis and PAM2 were injected once subcutaneously above mouse calvarial bones. After five days, both agonists induced bone formation mainly at endocranial surfaces. The injection resulted in progressively increased calvarial thickness during 21 days. Excessive new bone formation was mainly observed separated from bone resorption cavities. Anti-RANKL did not affect the increase of bone formation. Inflammation caused increased bone formation rate due to increased mineralizing surfaces as assessed by dynamic histomorphometry. In areas close to new bone formation, an abundance of proliferating cells was observed as well as cells robustly stained for Runx2 and alkaline phosphatase. PAM2 increased the mRNA expression of Lrp5, Lrp6 and Wnt7b, and decreased the expression of Sost and Dkk1. In situ hybridization demonstrated decreased Sost mRNA expression in osteocytes present in old bone. An abundance of cells expressed Wnt7b in Runx2-positive osteoblasts and ß-catenin in areas with new bone formation. These data demonstrate that inflammation, not only induces osteoclastogenesis, but also locally activates canonical WNT signaling and stimulates new bone formation independent on bone resorption.

The complement factor H-related protein-5 (CFHR5) exacerbates pathological bone formation in ankylosing spondylitis.

Ankylosing spondylitis (AS) is a chronic inflammatory disease, characterized by excessive new bone formation. We previously reported that the complement factor H-related protein-5 (CFHR5), a member of the human factor H protein family, is significantly elevated in patients with AS compared to other rheumatic diseases. However, the pathophysiological mechanism underlying new bone formation by CFHR5 is not fully understood. In this study, we revealed that CFHR5 and proinflammatory cytokines (TNF, IL-6, IL-17A, and IL-23) were elevated in the AS group compared to the HC group. Correlation analysis revealed that CFHR5 levels were not significantly associated with proinflammatory cytokines, while CFHR5 levels in AS were only positively correlated with the high CRP group. Notably, treatment with soluble CFHR5 has no effect on clinical arthritis scores and thickness at hind paw in curdlan-injected SKG, but significantly increased the ectopic bone formation at the calcaneus and tibia bones of the ankle as revealed by micro-CT image and quantification. Basal CFHR5 expression was upregulated in AS-osteoprogenitors compared to control cells. Also, treatment with CFHR5 remarkedly induced bone mineralization status of AS-osteoprogenitors during osteogenic differentiation accompanied by MMP13 expression. We provide the first evidence demonstrating that CFHR5 can exacerbate the pathological bone formation of AS. Therapeutic modulation of CFHR5 could be promising for future treatment of AS. KEY MESSAGES: Serum level of CFHR5 is elevated and positively correlated with high CRP group of AS patients. Recombinant CFHR5 protein contributes to pathological bone formation in in vivo model of AS. CFHR5 is highly expressed in AS-osteoprogenitors compared to disease control. Recombinant CFHR5 protein increased bone mineralization accompanied by MMP13 in vitro model of AS.

Periostin Promotes the Proliferation, Differentiation and Mineralization of Osteoblasts from Ovariectomized Rats.

Perimenopausal period causes a significant amount of bone loss, which results in primary osteoporosis (OP). The Periostin (Postn) may play important roles in the pathogenesis of OP after ovariectomized (OVX) rats. To identify the roles of Postn in the bone marrow mesenchymal stem cell derived osteoblasts (BMSC-OB) in OVX rats, we investigated the expression of Wnt/β-catenin signaling pathways in BMSC-OB and the effects of Postn on bone formation by development of BMSC-OB cultures. Twenty-four female Sprague-Dawley rats at 6 months were randomized into 3 groups: sham-operated (SHAM) group, OVX group and OVX+Postn group. The rats were killed after 3 months, and their bilateral femora and tibiae were collected for BMSC-OB culture, Micro-CT Analysis, Bone Histomorphometric Measurement, Transmission Electron Microscopy and Immunohistochemistry Staining. The dose/time-dependent effects of Postn on the proliferation, differentiation and mineralization of BMSC-OB and the expression of osteoblastic markers were measured in in vitro experiments. We found increased Postn increased bone mass, promoted bone formation of trabeculae, Wnt signaling and the osteogenic activity in osteoblasts in sublesional femur. Postn have the function to enhance cell proliferation, differentiation and mineralization at a proper concentration and incubation time. Interestingly, in BMSC-OB from OVX rats treated with the different dose of Postn, the osteoblastic markers expression and Wnt/β-catenin signaling pathways were significantly promoted. The direct effect of Postn may lead to inhibit excessive bone resorption and increase bone formation through the Wnt/β-catenin signaling pathways after OVX. Postn may play a very important role in the pathogenesis of OP after OVX.

Fluid-solid coupling numerical simulation of entire rat caudal vertebrae under dynamic loading

Trabeculae bone undergoes directional growth along the applied force under physiological loading. The growth of bone structure relies on the coordinated interplay among osteocytes, osteoblasts, and osteoclasts. Under normal circumstances, bone remodeling maintains a state of equilibrium. Excessive bone formation can lead to osteosclerosis, while excessive bone resorption can result in osteoporosis and osteonecrosis. The investigation of the structural characteristics of trabeculae and the mechanotransduction between bone cells plays a vital role in the treatment of bone-related diseases. In this study, a fluid-solid coupling model of the entire vertebral bone was established based on micro-CT images obtained from rat tail vertebrae subjected to tensile loading experiments. The flow characteristics of bone marrow and the mechanical response of osteocytes in different regions under physiological loading were investigated. The results revealed a U-shaped distribution of wall fluid shear stress (FSS) along the longitudinal axis in trabecular bone, with higher FSS regions exhibiting greater mechanical stimulation on osteocytes. These findings elucidate a positive correlation between the mechanical microenvironment among osteocytes, osteoblasts, and osteoclasts, providing potential strategies for the prevention and treatment of bone diseases.

VEGF Secretion Drives Bone Formation in Classical MAP2K1+ Melorheostosis.

Patients with classical melorheostosis exhibit exuberant bone overgrowth in the appendicular skeleton, resulting in pain and deformity with no known treatment. Most patients have somatic, mosaic mutations in MAP2K1 (encoding the MEK1 protein) in osteoblasts and overlying skin. As with most rare bone diseases, lack of affected tissue has limited the opportunity to understand how the mutation results in excess bone formation. The aim of this study was to create a cellular model to study melorheostosis. We obtained patient skin cells bearing the MAP2K1 mutation (affected cells), and along with isogenic control normal fibroblasts reprogrammed them using the Sendai virus method into induced pluripotent stem cells (iPSCs). Pluripotency was validated by marker staining and embryoid body formation. iPSCs were then differentiated to mesenchymal stem cells (iMSCs) and validated by flow cytometry. We confirmed retention of the MAP2K1 mutation in iMSCs with polymerase chain reaction (PCR) and confirmed elevated MEK1 activity by immunofluorescence staining. Mutation-bearing iMSCs showed significantly elevated vascular endothelial growth factor (VEGF) secretion, proliferation and collagen I and IV secretion. iMSCs were then differentiated into osteoblasts, which showed increased mineralization at 21 days and increased VEGF secretion at 14 and 21 days of differentiation. Administration of VEGF to unaffected iMSCs during osteogenic differentiation was sufficient to increase mineralization. Blockade of VEGF by bevacizumab reduced mineralization in iMSC-derived affected osteoblasts and in affected primary patient-derived osteoblasts. These data indicate that patient-derived induced pluripotent stem cells recreate the elevated MEK1 activity, increased mineralization, and increased proliferation seen in melorheostosis patients. The increased bone formation is driven, in part, by abundant VEGF secretion. Modifying the activity of VEGF (a known stimulator of osteoblastogenesis) represents a promising treatment pathway to explore. iPSCs may have wide applications to other rare bone diseases. © 2023 American Society for Bone and Mineral Research (ASBMR).

Hdac1 and Hdac2 positively regulate Notch1 gain-of-function pathogenic signaling in committed osteoblasts of male mice.

Skeletal development requires precise extrinsic and intrinsic signals to regulate processes that form and maintain bone and cartilage. Notch1 is a highly conserved signaling receptor that regulates cell fate decisions by controlling the duration of transcriptional bursts. Epigenetic molecular events reversibly modify DNA and histone tails by influencing the spatial organization of chromatin and can fine-tune the outcome of a Notch1 transcriptional response. Histone deacetylase 1 and 2 (HDAC1 and HDAC2) are chromatin modifying enzymes that mediate osteoblast differentiation. While an HDAC1-Notch interaction has been studied in vitro and in Drosophila, its role in mammalian skeletal development and disorders is unclear. Osteosclerosis is a bone disorder with an abnormal increase in the number of osteoblasts and excessive bone formation. Here, we tested whether Hdac1/2 contribute to the pathogenesis of osteosclerosis in a murine model of the disease owing to conditionally cre-activated expression of the Notch1 intracellular domain in immature osteoblasts. Importantly, selective homozygous deletions of Hdac1/2 in osteoblasts partially alleviate osteosclerotic phenotypes (Col2.3kb-Cre; TGRosaN1ICD/+ ; Hdac1flox/flox ; Hdac2flox/flox ) with a 40% decrease in bone volume and a 22% decrease in trabecular thickness in 4 weeks old when compared to male mice with heterozygous deletions of Hdac1/2 (Col2.3 kb-Cre; TGRosaN1ICD/+ ; Hdac1flox/+ ; Hdac2flox/+ ). Osteoblast-specific deletion of Hdac1/2 in male and female mice results in no overt bone phenotype in the absence of the Notch1 gain-of-function (GOF) allele. These results provide evidence that Hdac1/2 contribute to Notch1 pathogenic signaling in the mammalian skeleton. Our study on epigenetic regulation of Notch1 GOF-induced osteosclerosis may facilitate further mechanistic studies of skeletal birth defects caused by Notch-related GOF mutations in human patients, such as Adams-Oliver disease, congenital heart disease, and lateral meningocele syndrome.

Lumbar vertebral canal stenosis due to marked bone overgrowth after routine hemilaminectomy in a dog

BackgroundBone overgrowth after decompressive surgery for lumbar stenosis resulting in recurrence of neurological signs has not been reported in veterinary literature. However, there are few cases described in human medicine.Case presentationA 13-month-old entire female dog, a crossbreed between a Springer Spaniel and a Border Collie, weighing 24 kg, was referred with a 5-day history of progressive spastic paraplegia, indicative of a T3-L3 myelopathy. Magnetic resonance (MR) imaging revealed a right-sided L2-L3 compressive extradural lesion, compatible with epidural haemorrhage, which was confirmed by histopathology. The lesion was approached via right-sided L2-L3 hemilaminectomy and was successfully removed. One-year postoperatively the dog re-presented with pelvic limb ataxia. MR and computed tomography (CT) images demonstrated excessive vertebral bone formation affecting the right articular processes, ventral aspect of the spinous process of L2-L3, and contiguous vertebral laminae, causing spinal cord compression. Revision surgery was performed, and histopathology revealed normal or reactive osseous tissue with a possible chondroid metaplasia and endochondral ossification, failing to identify a definitive reason for the bone overgrowth. Nine-month postoperatively, imaging studies showed a similar vertebral overgrowth, resulting in minimal spinal cord compression. The patient remained stable with mild proprioceptive ataxia up until the last follow-up 18 months post-revision surgery.ConclusionThis is the first report in the veterinary literature of bone overgrowth after lumbar hemilaminectomy which resulted in neurological deficits and required a revision decompressive surgery.

Prevalence and Characterization of Dental and Skull-Bone Pathologies of the Raccoon Dog (Nyctereutes procyonoides) in Lithuania.

The present investigation endeavours to discern dental and non-dental pathologies affecting cranial structures of raccoon dogs, while focusing on cases of periodontitis. Furthermore, the study aims to conduct a comparative analysis based on sex and the nature of the pathologies encountered. The number of investigated skulls amounted to 126, including 76 males and 50 females. The predominant pathology identified was hypodontia, which accounted for 26.7% of males and 20% of females. Notably, the majority of hypodontia cases involved the absence of the mandibular third molar. Another noteworthy pathology was various stages of periodontitis, with rates ranging from 21.3% in males to 8% in females. Other pathologies, like tooth fractures and abrasion, were significantly less encountered. Excessive bone formation was relatively abundant and localized in specific areas-the parietal bone and the occipital regions. This tendency was observed in 8% of male cases and 6% of females. We found that the total number of dental and skull-bone pathologies is significantly more common in males than in females (p = 0.003). Additionally, the total number of various cases of periodontitis is more common in males too (p = 0.04).

Monostotic paget’s bone disease of the pelvis

Pagets disease is a metabolic disorder of the elderly characterized by an excessive bone resorption followed by an excessive and anarchic bone formation responsible for a bone remodeling. It is often asymptomatic of fortuitous discovery.

#3388 ASSOCIATIONS BETWEEN PHYSICAL ACTIVITY, PHYSICAL FUNCTION AND BONE METABOLISM MARKERS IN HAEMODIALYSIS PATIENTS: A PRELIMINARY CROSS-SECTIONAL STUDY

Abstract Background and Aims Chronic kidney disease (CKD) patients suffering from end-stage renal disease often undergo dialysis treatment. Haemodialysis (HD) patients spend most of their time in sedentary behaviour, having therefore poor physical function, as well as frequently develop mineral and bone disorders due to disease-induced systemic alterations such as abnormally high bone resorption rates exceeding bone formation. In healthy individuals, there is considerable evidence highlighting the associations between physical activity (PA), physical function (PF), and bone health. In HD patients, however, evidence on the association between these variables is still scarce. Therefore, the present preliminary study seeks to characterise HD patients in terms of their PA and PF, and to identify any associations between these and markers of bone metabolism. Method A cross-sectional design study recruited 88 adult HD patients (males: 68%, age: 66±14 years, dialysis vintage: 42±52 months) from three clinics in Portugal. Resting blood samples were collected from the patients’ fistula at the start of the second dialysis session of the week. Plasma levels of the bone markers tartrate-resistant acid phosphatase 5b (TRAP-5b) (IDS, Tyne and Wear, UK), and sclerostin (SOST) and receptor activator of nuclear factor kappa-Β ligand (RANKL) (Biomedica Immunoassays, Vienna, Austria) were measured by commercially-available enzyme-linked immunosorbent assays (ELISA), and osteocalcin (OCN) (Biogen, Madrid, Spain) and osteoprotegerin (OPG) (R&D Systems, Abingdon, UK) via DuoSet ELISA kits. PF was assessed by completing the Sit to Stand 60 (STS60), the STS5, the Incremental Shuttle Walk Test (ISWT), the Timed Up and Go (TUG), and handgrip strength (HGS). All participants worn tri-axial accelerometers continuously for a week to estimate PA levels. Results Accelerometers were worn for an average 13±2h/day and data showed that 81±11% of the time was spent in sedentary behaviour, and 18±10% in light PA. Associations between PA, PF and markers of bone metabolism are described in Table 1. Weekly sedentary time was associated with reduced agility (TUG), muscle endurance (STS60, ISWT), and muscle power and strength (STS5), whereas light PA levels were associated with an increment in overall PF. Also, light PA levels were associated with decreased TRAP-5b and OPG, but elevated circulating OCN, supporting a potential modulatory effect of PA on bone turnover. Decreased overall PF were associated with increased concentrations of OPG, with muscle endurance and strength associated with increased circulating TRAP-5b. Conclusion Our data suggests that sedentarism may be responsible for a reduced PF, which in turn was associated with increased inhibition of osteoclastogenesis via OPG activity. Yet, a rather small increase in PA levels may lead to PF gains and could be a trigger for OCN activity and TRAP-5b inhibition. Therefore, increasing PA levels may modulate bone metabolism through mechanisms that favor bone formation.

Engineered Sensory Nerve Guides Self-Adaptive Bone Healing via NGF-TrkA Signaling Pathway.

The upstream role of sensory innervation during bone homeostasis is widely underestimated in bone repairing strategies. Herein, a neuromodulation approach is proposed to orchestrate bone defect healing by constructing engineered sensory nerves (eSN) in situ to leverage the adaptation feature of SN during tissue formation. NGF liberated from ECM-constructed eSN effectively promotes sensory neuron differentiation and enhances CGRP secretion, which lead to improved RAOECs mobility and osteogenic differentiation of BMSC. In turn, such eSN effectively drives ossification in vivo via NGF-TrkA signaling pathway, which substantially accelerates critical size bone defect healing. More importantly, eSN also adaptively suppresses excessive bone formation and promotes bone remodeling by activating osteoclasts via CGRP-dependent mechanism when combined with BMP-2 delivery, which ingeniously alleviates side effects of BMP-2. In sum, this eSN approach offers a valuable avenue to harness the adaptive role of neural system to optimize bone homeostasis under various clinical scenario.

Bone mineral density in patients with chronic spinal cord injury: An observational study

Background: Spinal cord injury (SCI) is accompanied by loss of bone mass caused by accelerated bone remodeling, with bone resorption exceeding bone formation which causes net bone loss. The significance of osteoporosis after SCI is that it results in skeletal fragility and an increased risk of fractures. Complications from fractures lead to an increase not only in the associated morbidity and mortality, but also in the health-care costs that they generate. Aims and Objectives: The objective of the study was to evaluate bone mineral density (BMD) in patients with SCI in Indian population and to determine the effects of the neurological level, severity of injury, and mobility status on BMD. Materials and Methods: This study was a prospective and observational study conducted on 52 chronic SCI patients. After detailed history and examination, patients were assessed using American spinal injury association impairment scale following which BMD was assessed by Dual Energy X-ray Absorptiometry Scan. Correlation between the T score and neurological level, severity of injury and mobility status was assessed. P<0.05 was considered statistically significant. Results: Out of 52 patients included, 41 were having complete SCI and 35 were non-ambulatory. T score was significantly (P<0.001) lower in lumbar spine and both femur in complete SCI patients. The T score was indicative of increased osteoporosis in non-ambulatory patients. BMD did not differ significantly (P<0.059) in patients with relation to various neurological levels. Conclusion: From this study, we conclude that osteoporosis is commonly present in patients with complete SCI and non-ambulatory was more affected. Early mobilization of these patients reduces the development of osteoporosis.

Regulation of human ZNF687, a gene associated with Paget's disease of bone.

Mutations in Zinc finger 687 (ZNF687) were associated with Paget's disease of bone (PDB), a disease characterized by increased bone resorption and excessive bone formation. It was suggested that ZNF687 plays a role in bone differentiation and development. However, the mechanisms involved in ZNF687 regulation remain unknown. This study aimed to obtain novel knowledge regarding ZNF687 transcriptional and epigenetic regulation. Through in silico analysis, we hypothesized three ZNF687 promoter regions located upstream exon 1A, 1B, and 1C and denominated promoter regions 1, 2, and 3, respectively. Their functionality was confirmed by luciferase activity assays and positive/negative regulatory regions were identified using promoter deletions constructs. In silico analysis revealed a high density of CpG islands in these promoter regions and in vitro methylation suppressed promoters' activity. Using bioinformatic approaches, bone-associated transcription factor binding sites containing CpG dinucleotides were identified, including those for NFκB, PU.1, DLX5, and SOX9. By co-transfection in HEK293 and hFOB cells, we found that DLX5 specifically activated ZNF687 promoter region 1, and its methylation impaired DLX5-driven promoter stimulation. NFκB repressed and activated promoter regions 1 and 2, respectively, and these activities were affected by methylation. PU.1 induced ZNF687 promoter region 1 which was affected by methylation. SOX9 differentially regulated ZNF687 promoters in HEK293 and hFOB cells that were impaired after methylation. In conclusion, this study provides novel insights into ZNF687 regulation by demonstrating that NFκB, PU.1, DLX5, and SOX9 are regulators of ZNF687 promoters, and DNA methylation influences their activity. The contribution of the dysregulation of these mechanisms in PDB should be further elucidated.