Current Aspects on the Pathophysiology of Bone Metabolic Defects during Progression of Scoliosis in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1), which is the most common phacomatoses, is an autosomal dominant disorder characterized by clinical presentations in various tissues and organs, such as the skin, eyes and nervous and skeletal systems. The musculoskeletal implications of NF1 include a variety of deformities, including scoliosis, kyphoscoliosis, spondylolistheses, congenital bony bowing, pseudarthrosis and bone dysplasia. Scoliosis is the most common skeletal problem, affecting 10–30% of NF1 patients. Although the pathophysiology of spinal deformities has not been elucidated yet, defects in bone metabolism have been implicated in the progression of scoliotic curves. Measurements of Bone Mineral Density (BMD) in the lumbar spine by using dual energy absorptiometry (DXA) and quantitative computer tomography (QCT) have demonstrated a marked reduction in Z-score and osteoporosis. Additionally, serum bone metabolic markers, such as vitamin D, calcium, phosphorus, osteocalcin and alkaline phosphatase, have been found to be abnormal. Intraoperative and histological vertebral analysis confirmed that alterations of the trabecular microarchitecture are associated with inadequate bone turnover, indicating generalized bone metabolic defects. At the molecular level, loss of function of neurofibromin dysregulates Ras and Transforming Growth factor-β1 (TGF-β1) signaling and leads to altered osteoclastic proliferation, osteoblastic activity and collagen production. Correlation between clinical characteristics and molecular pathways may provide targets for novel therapeutic approaches in NF1.

Microstructure, Mechanical Properties, Degradation Behavior, and Implant Testing of Hot-Rolled Biodegradable ZKX500 Magnesium Alloy

Currently, orthopedic metallic implants are mostly made of stainless steel and titanium alloys. After healing, patients are usually required to undergo a secondary surgery for implant removal, which not only poses a medical risk but also costs medical resources. Magnesium-based biodegradable implants that can be absorbed by humans promote osteoblastic activity during the degradation and inhibit the formation of osteoclasts. Moreover, magnesium can be detected by X-ray, and this can help doctors to perform postoperative diagnosis and treatment, which is beneficial for patients. In this study, a ZKX500 Mg alloy bone plate was prepared through rolling. In addition to the microstructure and the mechanical properties of the hot-rolled ZKX500 Mg alloy, its in vitro corrosion behavior under different heat treatment conditions is discussed. A 6-month mini-pig implantation test was conducted using the fabricated ZKX500 Mg alloy bone plate and bone screws. The in vivo degradation mechanism and new bone formation were observed using computed tomography images. The pig recovered well, and the results can serve as an important reference for clinical applications. In addition, another important contribution of this study is that it can help the field of orthopedics to better understand the biodegradable magnesium alloy.

Bone Biopsy for Histomorphometry in Chronic Kidney Disease (CKD): State-of-the-Art and New Perspectives

The use of bone biopsy for histomorphometric analysis is a quantitative histological examination aimed at obtaining quantitative information on bone remodeling, structure and microarchitecture. The labeling with tetracycline before the procedure also allows for a dynamic analysis of the osteoblastic activity and mineralization process. In the nephrological setting, bone biopsy is indicated to confirm the diagnosis of subclinical or focal osteomalacia and to characterize the different forms of renal osteodystrophy (ROD). Even if bone biopsy is the gold standard for the diagnosis and specific classification of ROD, the use of this approach is very limited. The main reasons for this are the lack of widespread expertise in performing or interpreting bone biopsy results and the cost, invasiveness and potential pain associated with the procedure. In this regard, the sedation, in addition to local anesthesia routinely applied in Italian protocol, significantly reduces pain and ameliorates the pain perception of patients. Concerning the lack of widespread expertise, in Italy a Hub/Spokes model is proposed to standardize the analyses, optimizing the approach to CKD patients and reducing the costs of the procedure. In addition, new tools offer the possibility to evaluate the osteogenic potential or the ability to form bone under normal and pathological conditions, analyzing mesenchymal stem cells and their ability to differentiate in the osteogenic lineage. In the same way, circulating microRNAs are suggested as a tool for exploring osteogenic potential. The combination of different diagnostic approaches and the optimization of the bioptic procedure represent a concrete solution to spread the use of bone biopsy and optimize CKD patient management.

The effect of mesenchymal stem cells, demineralized bone graft and platelet-rich plasma on osteogenesis in rat tibia defects

Aim: Deformities of the jaw and face are often caused by infection, inflammation, and cystic and neoplastic pathological conditions. Defects with various aetiologies should be repaired promptly using the most appropriate approach to reconstruct the anatomical form. To treat defects, bone grafts with various combinations have been used. In particular, combinations including cellular products to enhance osteogenic properties have been implemented. In this study, we aimed to investigate the effects of different materials and cells on bone defects by using mesenchymal stem cells (MSCs), which are thought to have a positive effect on healing, demineralized bone graft (DMB) and platelet-rich plasma (PRP). Methodology: We used 55 female rats weighing between 200-250 g, four of which were used to obtain platelet-rich plasma. The remaining animals were divided into five groups. Group I (n = 6) was the operative control group, Group II (n = 24) was given DMB, Group III (n = 24) was given DMB+PRP, Group IV (n = 24) was given MSC+DBG and Group V (n = 24) was given DMB+PRP+MSC applied to rat tibial defects (10 mm x 3 mm x 2 mm). Results: Statistically significant differences were observed in bone osteoblastic activity in tibia defects among the groups (p<0.05). Conclusion: Bone regeneration was significantly improved in groups where MSCs were used in combination with DMB and PRP. How to cite this article: Erdoğmuş Z, Gülsün B. The effect of mesenchymal stem cells, demıneralızed bone graft and platelet-rıch plasma on osteogenesıs ın rat tıbıa defects. Int Dent Res 2021;11(Suppl.1):47-55. https://doi.org/10.5577/intdentres.2021.vol11.suppl1.8 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Staphylococcus aureus internalization impairs osteoblastic activity and early differentiation process

Staphylococcus aureus is the most frequent aetiology of bone and joint infections (BJI) and can cause relapsing and chronic infections. One of the main factors involved in the chronicization of staphylococcal BJIs is the internalization of S. aureus into osteoblasts, the bone-forming cells. Previous studies have shown that S. aureus triggers an impairment of osteoblasts function that could contribute to bone loss. However, these studies focused mainly on the extracellular effects of S. aureus. Our study aimed at understanding the intracellular effects of S. aureus on the early osteoblast differentiation process. In our in vitro model of osteoblast lineage infection, we first observed that internalized S. aureus 8325-4 (a reference lab strain) significantly impacted RUNX2 and COL1A1 expression compared to its non-internalized counterpart 8325-4∆fnbAB (with deletion of fnbA and fnbB). Then, in a murine model of osteomyelitis, we reported no significant effect for S. aureus 8325-4 and 8325-4∆fnbAB on bone parameters at 7 days post-infection whereas S. aureus 8325-4 significantly decreased trabecular bone thickness at 14 days post-infection compared to 8325-4∆fnbAB. When challenged with two clinical isogenic strains isolated from initial and relapse phase of the same BJI, significant impairments of bone parameters were observed for both initial and relapse strain, without differences between the two strains. Finally, in our in vitro osteoblast infection model, both clinical strains impacted alkaline phosphatase activity whereas the expression of bone differentiation genes was significantly decreased only after infection with the relapse strain. Globally, we highlighted that S. aureus internalization into osteoblasts is responsible for an impairment of the early differentiation in vitro and that S. aureus impaired bone parameters in vivo in a strain-dependent manner.

Piezoelectric Microvibration Mitigates Estrogen Loss-Induced Osteoporosis and Promotes Piezo1, MicroRNA-29a and Wnt3a Signaling in Osteoblasts

Biophysical stimulation alters bone-forming cell activity, bone formation and remodeling. The effect of piezoelectric microvibration stimulation (PMVS) intervention on osteoporosis development remains uncertain. We investigated whether 60 Hz, 120 Hz, and 180 Hz PMVS (0.05 g, 20 min/stimulation, 3 stimulations/week for 4 consecutive weeks) intervention affected bone integrity in ovariectomized (OVX) mice or osteoblastic activity. PMVS (120 Hz)-treated OVX mice developed fewer osteoporosis conditions, including bone mineral density loss and trabecular microstructure deterioration together with decreased serum resorption marker CTX-1 levels, as compared to control OVX animals. The biomechanical strength of skeletal tissue was improved upon 120 Hz PMVS intervention. This intervention compromised OVX-induced sparse trabecular bone morphology, osteoblast loss, osteoclast overburden, and osteoclast-promoting cytokine RANKL immunostaining and reversed osteoclast inhibitor OPG immunoreactivity. Osteoblasts in OVX mice upon PMVS intervention showed strong Wnt3a immunoreaction and weak Wnt inhibitor Dkk1 immunostaining. In vitro, PMVS reversed OVX-induced loss in von Kossa-stained mineralized nodule formation, Runx2, and osteocalcin expression in primary bone-marrow stromal cells. PMVS also promoted mechanoreceptor Piezo1 expression together with increased microRNA-29a and Wnt3a expression, whereas Dkk1 rather than SOST expression was repressed in MC3T3-E1 osteoblasts. Taken together, PMVS intervention promoted Piezo1, miR-29a, and Wnt signaling to upregulate osteogenic activity and repressed osteoclastic bone resorption, delaying estrogen deficiency-induced loss in bone mass and microstructure. This study highlights a new biophysical remedy for osteoporosis.

Effect of Zoledronic Acid Combined With Metformin on Bone of Db/db Mice

Background Diabetic Osteoporosis (DO) is a complication of diabetes. As a first-line medication for diabetes, metformin combined with the anti-osteoporosis drug zoledronic acid is still unclear whether it is effective in treating DO. In this work, we explored the effect of metformin combined with zoledronic acid in the treatment of DO.Methods 12-week-old db/db mice were randomly divided into db/db group, ZA (zoledronic acid) group, MET (metformin) group, CMT (combination therapy group) group, Set WT (wild-type) mice of the same strain and age as the blank control group. Body weight and blood glucose were measured every 2 weeks. After 10 weeks, samples were taken for pathology and imaging related tests.Results (1) The body weight of db/db mice treated with metformin was stable and blood glucose was decreased. (2) After HE staining, db/db mice treated with metformin showed decreased adipocytes, increased blood cells and blood vessels in bone marrow cavity; db/db mice treated with zoledronic acid showed increased trabeculae. The number of bone trabeculae and blood vessels in the bone increased after the combined use of the two drugs. (3) By OPG staining and semi-quantitative analysis, db/db mice had the lowest osteoblastic activity. db/db mice treated with metformin had higher osteoblastic activity than those treated with zoledronic acid, and the osteoblastic activity of CMT was higher than that treated with ZA group or MET group. (4) After TE staining, semi-quantitative analysis showed that the number of bone lacunae in WT group was the least, the number of bone lacunae in ZA group and CMT group was significantly lower than that in db/db group, but the number of bone lacunae in MET group was not significant. (5) The bone morphological analysis of db/db mice in the CMT group was significantly better than that of MET or ZA alone by micro-CT scanning and bone tissue parameters determination.Conclusion ZA combined with MET has better anti-bone loss effect than zoledronic acid or metformin alone in db/db mice.

18F-Sodium Fluoride PET as a Diagnostic Modality for Metabolic, Autoimmune, and Osteogenic Bone Disorders: Cellular Mechanisms and Clinical Applications

In a healthy body, homeostatic actions of osteoclasts and osteoblasts maintain the integrity of the skeletal system. When cellular activities of osteoclasts and osteoblasts become abnormal, pathological bone conditions, such as osteoporosis, can occur. Traditional imaging modalities, such as radiographs, are insensitive to the early cellular changes that precede gross pathological findings, often leading to delayed disease diagnoses and suboptimal therapeutic strategies. 18F-sodium fluoride (18F-NaF)-positron emission tomography (PET) is an emerging imaging modality with the potential for early diagnosis and monitoring of bone diseases through the detection of subtle metabolic changes. Specifically, the dissociated 18F- is incorporated into hydroxyapatite, and its uptake reflects osteoblastic activity and bone perfusion, allowing for the quantification of bone turnover. While 18F-NaF-PET has traditionally been used to detect metastatic bone disease, recent literature corroborates the use of 18F-NaF-PET in benign osseous conditions as well. In this review, we discuss the cellular mechanisms of 18F-NaF-PET and examine recent findings on its clinical application in diverse metabolic, autoimmune, and osteogenic bone disorders.

Genistein acts in bone metabolism and improves peri-implant healing in rats with estrogen deficiency

The present study aimed to evaluate the peri-implantar bone healing in the presence of genistein treatment in ovariectomized rats. Thirty female rats with 4 months old were divided into 3 groups according to the experimental condition and the drug treatment: SHAM (rats submitted to the fictional surgery and gavage with 0.9% saline solution); OVX (rats submitted to bilateral ovariectomy and gavage with 0.9% saline solution); OVX GEN (rats submitted to bilateral ovariectomy and gavage with 1mg/day of genistein). 60 implants were installed, with two implants in each animal. The calcified group was subjected microcomputerized tomography and the parameters analysed was bone volume per tissue volume (BV/TV) and connective density (Cnn.Dn). The decalcified samples were evaluated through immunolabeling analysis, in order to detect the presence of RUNX2, Alkaline Phosphatase, Osteocalcin, Osteopontin and TRAP. All the quantitative data were submitted to the normality curve to determine the most adequate test. The significance level of p<0.05 was considered for all tests. The morphometric analysis of the OVX GEN group showed higher percentage of bone volume and lower connective density when compared with OVX. Immunohistochemical analysis favors expression. For the markers that positively label osteoblastic activity. This study shows that genistein therapy improves peri-implant bone healing in ovariectomized rats.