Tumor growth for remodeling process: A 2D approach

This paper aims to present a comprehensive framework for coupling tumor-bone remodeling processes in a 2-dimensional geometry. This is achieved by introducing a bio-inspired damage that represents the growing tumor, which subsequently affects the main populations involved in the remodeling process, namely, osteoclasts, osteoblasts, and bone tissue. The model is constructed using a set of differential equations based on the Komarova's and Ayati's models, modified to incorporate the bio-inspired damage that may result in tumor mass formation. Three distinct models were developed. The first two models are based on the Komarova's governing equations, with one demonstrating an osteolytic behavior and the second one an osteoblastic model. The third model is a variation of Ayati's model, where the bio-inspired damage is induced through the paracrine and autocrine parameters, exhibiting an osteolytic behavior. The obtained results are consistent with existing literature, leading us to believe that our in-silico experiments will serve as a cornerstone for paving the way towards targeted interventions and personalized treatment strategies, ultimately improving the quality of life for those affected by these conditions.

DDIT3 deficiency accelerates bone remodeling during bone healing by enhancing osteoblast and osteoclast differentiation through ULK1-mediated autophagy

The coordination of osteoblasts and osteoclasts is essential for bone remodeling. DNA damage inducible script 3 (DDIT3) is an important regulator of bone and participates in cell differentiation, proliferation, autophagy, and apoptosis. However, its role in bone remodeling remains unexplored. Here, we found that Ddit3 knockout (Ddit3-KO) enhanced both bone formation and resorption. The increased new bone formation and woven bone resorption, i.e., enhanced bone remodeling capacity, was found to accelerate bone defect healing in Ddit3-KO mice. In vitro experiments showed that DDIT3 inhibited both osteoblast differentiation and Raw264.7 cell differentiation by regulating autophagy. Cell coculture assay showed that Ddit3-KO decreased the ratio of receptor activator of nuclear factor-κβ ligand (RANKL) to osteoprotegerin (OPG) in osteoblasts, and Ddit3-KO osteoblasts inhibited osteoclast differentiation. Meanwhile, DDIT3 knockdown (DDIT3-sh) increased receptor activator of nuclear factor-κβ (RANK) expression in Raw264.7 cells, and DDIT3-sh Raw264.7 cells promoted osteoblast differentiation, whereas, DDIT3 overexpression had the opposite effect. Mechanistically, DDIT3 promoted autophagy partly by increasing ULK1 phosphorylation at serine555 (pULK1-S555) and decreasing ULK1 phosphorylation at serine757 (pULK1-S757) in osteoblasts, thereby inhibiting osteoblast differentiation. DDIT3 inhibited autophagy partly by decreasing pULK1-S555 in Raw264.7 cells, thereby suppressing osteoclastic differentiation. Taken together, our data indicate that DDIT3 is one of the elements regulating bone remodeling and bone healing, which may become a potential target in bone defect treatment.

Bone remodelling prediction using mechanical stimulus with bone connectivity theory in porous implants

Strain energy density (SED) is considered to be the primary remodelling stimulus influencing the process of bone growth into porous implants. A bone remodelling algorithm incorporating the concept of bone connectivity, that newly formed bone should only grow from existing bone, was developed to provide a more biologically realistic simulation of bone growth. Results showed that the new algorithm prevented the occurrence of unconnected mature bone within porous implants, an unrealistic phenomenon observed using conventional adaptive elasticity theories. The bone connectivity algorithm had minimal effect (0.67% difference) on the final bone density distribution for standard bending and torsional moment cases. For a porous implant model, both algorithms, with and without bone connectivity implementation, reached the same final stiffness, with a difference of less than 0.01%. The bone connectivity algorithm predicted a slower and more gradual bone remodelling process, requiring at least 50% additional time for full remodelling compared to the conventional adaptive elasticity algorithm, which should be accounted for in the planning of rehabilitation strategies. The developed modelling can be employed to improve porous implant designs to achieve better clinical outcomes.

Phf7 has impacts on the body growth and bone remodeling by regulating testicular hormones in male mice

PHD finger protein 7 (Phf7) is a member of the PHF family proteins, which plays important roles in spermiogenesis. Phf7 is expressed in the adult testes and its deficiency causes male infertility. In this study, we tried to find the causal relationship between Phf7 deficiency and reduced growth retardation which were found in null knock-out (Phf7-/-) mice. Phf7-/- mice were born normally in the Mendelian ratio. However, the Phf7-/- males showed decreased body weight gain, bone mineral density, and bone mineral content compared to those in wild-type (WT) mice. Histological analysis for tibia revealed increased number of osteoclast cells in Phf7-/- mice compared with that in WT mice. When we analyzed the expressions for marker genes for the initial stage of osteoclastogenesis, such as receptor activator of nuclear factor kappa B (Rank) in tibia, there was no difference in the mRNA levels between Phf7-/- and WT mice. However, the expression of tartrate-resistant acid phosphatase (Trap), a mature stage marker gene, was significantly higher in Phf7-/- mice than in WT mice. In addition, the levels of testosterone and dihydrotestosterone (DHT), more potent and active form of testosterone, were significantly reduced in the testes of Phf7-/- mice compared to those in WT mice. Furthermore, testicular mRNA levels for steroidogenesis marker genes, namely Star, Cyp11a1, Cyp17a1 and 17β-hsd, were significantly lower in Phf7-/- mice than in WT mice. In conclusion, these results suggest that Phf7 deficiency reduces the production of male sex hormones and thereby impairs associated bone remodeling.

Hypobaric hypoxia aggravates osteoarthritis via the alteration of the oxygen environment and bone remodeling in the subchondral zone

A high prevalence of osteoarthritis (OA) has been observed among individuals living at high altitudes, and hypobaric hypoxia (HH) can cause bone mass and strength deterioration. However, the effect of HH on OA remains unclear. In this study, we aimed to explore the impact of HH on OA and its potential mechanisms. A rat knee OA model was established by surgery, and the rats were bred in an HH chamber simulating a high-altitude environment. Micro-computed tomography (Micro-CT), histological analysis, and RNA sequencing were performed to evaluate the effects of HH on OA in vivo. A hypoxic co-culture model of osteoclasts and osteoblasts was also established to determine their effects on chondrogenesis in vitro. Cartilage degeneration significantly worsened in the HH-OA group compared to that in the normoxia-OA (N-OA) group, 4 weeks after surgery. Micro-CT analysis revealed more deteriorated bone mass in the HH-OA group than in the N-OA group. Decreased hypoxia levels in the cartilage and enhanced hypoxia levels in the subchondral bone were observed in the HH-OA group. Furthermore, chondrocytes cultured in a conditioned medium from the hypoxic co-culture model showed decreased anabolism and extracellular matrix compared to those in the normoxic model. RNA sequencing analysis of the subchondral bone indicated that the glycolytic signaling pathway was highly activated in the HH-OA group. HH-related OA progression was associated with alterations in the oxygen environment and bone remodeling in the subchondral zone, which provided new insights into the pathogenesis of OA.

Exercise and osteoimmunology in bone remodeling

Bones can form the scaffolding of the body, support the organism, coordinate somatic movements, and control mineral homeostasis and hematopoiesis. The immune system plays immune supervisory, defensive, and regulatory roles in the organism, which mainly consists of immune organs (spleen, bone marrow, tonsils, lymph nodes, etc.), immune cells (granulocytes, platelets, lymphocytes, etc.), and immune molecules (immune factors, interferons, interleukins, tumor necrosis factors, etc.). Bone and the immune system have long been considered two distinct fields of study, and the bone marrow, as a shared microenvironment between the bone and the immune system, closely links the two. Osteoimmunology organically combines bone and the immune system, elucidates the role of the immune system in bone, and creatively emphasizes its interdisciplinary characteristics and the function of immune cells and factors in maintaining bone homeostasis, providing new perspectives for skeletal-related field research. In recent years, bone immunology has gradually become a hot spot in the study of bone-related diseases. As a new branch of immunology, bone immunology emphasizes that the immune system can directly or indirectly affect bones through the RANKL/RANK/OPG signaling pathway, IL family, TNF-α, TGF-β, and IFN-γ. These effects are of great significance for understanding inflammatory bone loss caused by various autoimmune or infectious diseases. In addition, as an external environment that plays an important role in immunity and bone, this study pays attention to the role of exercise-mediated bone immunity in bone reconstruction.

Current perspectives on the multiple roles of osteoclasts: Mechanisms of osteoclast-osteoblast communication and potential clinical implications

Bone remodeling is a complex process involving the coordinated actions of osteoblasts and osteoclasts to maintain bone homeostasis. While the influence of osteoblasts on osteoclast differentiation is well established, the reciprocal regulation of osteoblasts by osteoclasts has long remained enigmatic. In the past few years, a fascinating new role for osteoclasts has been unveiled in promoting bone formation and facilitating osteoblast migration to the remodeling sites through a number of different mechanisms, including the release of factors from the bone matrix following bone resorption and direct cell-cell interactions. Additionally, considerable evidence has shown that osteoclasts can secrete coupling factors known as clastokines, emphasizing the crucial role of these cells in maintaining bone homeostasis. Due to their osteoprotective function, clastokines hold great promise as potential therapeutic targets for bone diseases. However, despite long-standing work to uncover new clastokines and their effect in vivo, more substantial efforts are still required to decipher the mechanisms and pathways behind their activity in order to translate them into therapies. This comprehensive review provides insights into our evolving understanding of the osteoclast function, highlights the significance of clastokines in bone remodeling, and explores their potential as treatments for bone diseases suggesting future directions for the field.

Fat mass and obesity-associated protein (FTO) affects midpalatal suture bone remodeling during rapid maxillary expansion

BACKGROUND

The fat mass and obesity-associated protein (FTO) is an RNA demethylase that contributes to several physiological processes. Nonetheless, the impact of FTO on bone remodeling in the midpalatal suture while undergoing rapid maxillary expansion (RME) remains unclear.

METHODS

First, to explore the expression of FTO in the midpalatal suture during RME, six rats were randomly divided into two groups: Expansion group and Sham group (springs without being activated). Then, suture mesenchymal stem cells (SuSCs) were isolated as in vitro model. The expression of FTO was knocked down by small interfering RNA to study the effect of FTO on the osteogenic differentiation of SuSCs. Finally, to evaluate the function of FTO in the process of bone remodeling in the midpalatal suture, ten rats were randomly divided into two groups: FB23-2 group (10 μM, a small molecule inhibitor of FTO) and DMSO group (control).

RESULTS

Increased arch width and higher expression of OCN and FTO in the midpalatal area were observed in expansion group (P < .05). In the in vitro model, the mRNA expression levels of Runx2, Bmp2, Col1a1, Spp1, and Tnfrsf11b were decreased (P < .05) upon knocking down FTO. Additionally, the protein levels of RUNX2 and OPN were also decreased (P < 0.05). Adding FB23-2, a small-molecule inhibitor targeting FTO, to the medium of SuSCs caused a decrease in the mRNA expression levels of Runx2, Bmp2, Col1a1, Spp1, and Tnfrsf11b (P < 0.05). There was a statistically significant difference in evaluating the expression of OCN and OPN on the palatal suture between the FB23-2 and DMSO groups (P < .05).

LIMITATION

The molecular mechanisms by which FTO regulates SuSCs osteogenesis remain to be elucidated. The FTO conditional knock out mouse model can be established to further elucidate the role of FTO during RME.

CONCLUSION

FTO contributes to the osteogenic differentiation of SuSCs and plays a promoting role in midpalatal suture bone remodeling during the RME.

How do the dimensions of peri-implant mucosa affect marginal bone loss in equicrestal and subcrestal position of implants? A 1-year clinical trial

INTRODUCTION

There is evidence that the apico-coronal implant position and the mucosal phenotype can affect the extent of peri-implant bone loss. This clinical trial analyzes the bone remodeling and marginal bone loss that occur around conical-connection implants placed equicrestally and subcrestally, assessing the effect of the peri-implant soft-tissue phenotype.

METHODS

Fifty-one patients received 56 implants of distinct diameters (3.5 mm Ø n = 6; 4.3 mm Ø n = 41; 5 mm Ø n = 9) in the posterior part of the maxilla or mandible. The implants were placed equicrestally, 1 mm subcrestally and >1 mm subcrestally, depending on the initial supracrestal tissue height (STH). After 3 months of non-submerged healing, single metal-ceramic screw-retained implant-supported crowns were placed. Longitudinal measurements of STH, mucosal thickness and keratinized mucosa width (KMW) were made at the time of implant placement (T0), crown placement (T1), and after 3 (T2) and 6 months (T3) of prosthetic loading. At each of these points, a radiographic evaluation of bone remodeling and marginal bone loss was also performed.

RESULTS

STH was significantly greater for implants placed >1 mm subcrestally than for those placed 1 mm subcrestally. After 12 months of follow-up, a very significant (p < 0.001) loss of KMW was observed, in addition to a marginal bone loss of 0.08 ± 0.1, 0.15 ± 0.2, and 0.14 ± 0.2 mm in the groups placed equicrestally, 1 mm subcrestally and >1 mm subcrestally, respectively. After the multiple linear regression, marginal bone loss was found to depend primarily on KMW (β = -0.43), while also being affected by STH (β = 0.32) and implant diameter (β = -0.28).

CONCLUSIONS

Marginal bone loss may be influenced by the position with respect to the bone crest, as well as the KMW, STH, and implant diameter. However, more well-controlled studies are needed to verify these above-mentioned findings with different implant designs and connections.

Sildenafil delays bone remodeling of fractured femora in aged mice by reducing the number and activity of osteoclasts within the callus tissue

The elderly exhibit a reduced healing capacity after fracture, which is often associated with delayed or failed bone healing. This is due to a plethora of factors, such as an impaired bone vascular system and delayed angiogenesis. The phosphodiesterase-5 (PDE-5) inhibitor sildenafil exerts pro-angiogenic and pro-osteogenic effects. Hence, we herein investigated in aged mice whether sildenafil can improve fracture healing. For this purpose, 40 aged CD-1 mice (16-18 months) were daily treated with 5 mg/kg body weight sildenafil (n = 20) or vehicle (control, n = 20) by oral gavage. The callus tissue of their femora was analyzed at 2 and 5 weeks after fracture by X-ray, biomechanics, micro-computed tomography (µCT), histology, immunohistochemistry as well as Western blotting. These analyses revealed a significantly increased bone volume and higher ratio of callus to femoral bone diameter in sildenafil-treated mice at 5 weeks after fracture when compared to controls. This was associated with a reduced number and activity of osteoclasts at 2 weeks after fracture, most likely caused by an increased expression of osteoprotegerin (OPG). Taken together, these findings indicate that sildenafil does not improve fracture healing in the elderly but delays the process of bone remodeling most likely by reducing the number and activity of osteoclasts within the callus tissue.

Associations of Changes in Bone Turnover Markers with Change in Bone Mineral Density in Kidney Transplant Patients

BACKGROUND

Bone loss after kidney transplantation is highly variable. We investigated whether changes in bone turnover markers associate with bone loss during the first post-transplant year.

METHODS

Bone mineral density (BMD) was measured at 0 and 12 months, with biointact parathyroid hormone, bone-specific alkaline phosphatase (BALP), intact procollagen type I N -terminal propeptide (PINP), and tartrate-resistant acid phosphatase isoform 5b (TRAP5b) measured at 0, 3, and 12 months post-transplant ( N =209). Paired transiliac bone biopsies were available in a subset ( n =49). Between-group differences were evaluated by Student's t test, Wilcoxon signed-rank test, or Pearson's chi-squared test.

RESULTS

Changes in BMD varied from -22% to +17%/yr. Compared with patients with no change (±2.5%/yr), patients who gained BMD had higher levels of parathyroid hormone (236 versus 136 pg/ml), BALP (31.7 versus 18.8 μ g/L), and Intact PINP (121.9 versus 70.4 μ g/L) at time of transplantation; a greater decrease in BALP (-40% versus -21%) and Intact PINP (-43% versus -13%) by 3 months; and lower levels of Intact PINP (36.3 versus 60.0 μ g/L) at 12 months post-transplant. Patients who lost BMD had a less marked decrease, or even increase, in Intact PINP (+22% versus -13%) and TRAP5b (-27% versus -43%) at 3 months and higher Intact PINP (83.7 versus 60.0 μ g/L) and TRAP5b (3.89 versus 3.16 U/L) at 12 months compared with patients with no change. If none of the biomarkers decreased by the least significant change at 3 months, an almost two-fold (69% versus 36%) higher occurrence of bone loss was seen at 12 months post-transplant.

CONCLUSIONS

Bone loss after kidney transplantation was highly variable. Resolution of high bone turnover, as reflected by decreasing bone turnover markers, associated with BMD gain, while increasing bone turnover markers associated with bone loss.

Numerical calculation of streaming potential around osteocytes under human gait loading

Streaming potential is a type of stress-generated potential in bone that affects the electrical environment of osteocytes and may play a role in bone remodeling. Because the electrical environment around osteocytes has been difficult to measure experimentally until now, a numerical solid-liquid-streaming potential coupling method was proposed to analyze the streaming potential generated by bone deformation in the lacunae and canaliculus network (LCN) of the bone. Using this method, the cellular shear stress caused by liquid flow on the osteocyte surface was first calculated, and the results were consistent with those reported in the literature. Subsequently, the streaming potentials in the LCN caused by bone matrix deformation under an external gait load were calculated numerically. The results showed that the streaming potential increased slowly in the lacuna and relatively rapidly in the canaliculus and that the streaming potential increased with a decrease in the radius or an increase in the length of the canaliculus. The results also showed that relatively large gaps between the lacunae and osteocytes could induce higher streaming potentials under the same loading.

A retrospective study of alveolar bone remodelling after anterior retraction in orthodontic tooth extraction cases with clear aligners and fixed appliances

OBJECTIVES

To evaluate alveolar bone dimensions and its relationship with tooth movement (retraction, intrusion and torque) during orthodontic treatment with fixed appliance and clear aligners.

METHODS

Thirty-two patients were included in this retrospective clinical study. Cone beam computed tomography (CBCT) was collected before and after treatment to measure the volume of dehiscence and fenestrations in the maxillary anterior region, anterior alveolar bone thickness and height and degree of tooth movement. Rank-sum tests were used to compare the differences in alveolar bone defect volumes between clear aligners and fixed appliance, multiple linear regression analysis was used for study evaluation, and kappa statistics were used to assess internal consistency and test-retest reliability.

RESULTS

Post-operatively, most alveolar bone defects occurred on the labial side. The incidence of bone fenestration was 23.96% in the clear aligner group and 26.18% in the fixed appliance group, which was higher than the incidence of bone dehiscence (5.21%). The labial bone height decreased by 0.272 mm, and the palatal bone height increased by 0.617 mm for every 1 mm downward intrusion of the anterior tooth apex in the fixed appliance group. In the clear aligner group, there was no significant change in the labial bone height, and the palatal bone height decreased by 0.447 mm for every 1 mm of anterior tooth retraction coronally.

CONCLUSIONS

In the fixed appliance group, anterior tooth intrusion and retraction may have led to alveolar bone resorption by its compression at the cervical level. This study provides a three-dimensional tooth movement evaluation method by using CBCT.

Influence of intramedullary pressure on Lacuno-Canalicular fluid flow: A systematic review

While most of current models investigating bone remodelling are based on matrix deformation, intramedullary pressure also plays a role. Bone remodelling is orchestrated by the Lacuno-Canalicular Network (LCN) fluid-flow. The aim of this review was hence to assess the influence of intramedullary pressure on the fluid circulation within the LCN. Three databases (Science Direct, Web of Science, and PubMed) were used. The first phase of the search returned 731 articles, of which 9 respected the inclusion/exclusion criteria and were included. These studies confirm the association between intramedullary pressure and fluid dynamics in the LCN. Among the included studies, 7 experimental studies using animal models and 2 numerical models were found. The studies were then ranked according to the nature of the applied loading, either axial compression or direct cyclic intramedullary pressure. The current review revealed that there is an influence of intramedullary pressure on LCN fluid dynamics and that this influence depends on the magnitude and the frequency of the applied pressure. Two studies confirmed that the influence was effective even without bone matrix deformation. While intramedullary pressure is closely associated with LCN fluid, there is a severe lack of studies on this topic. STATEMENT OF SIGNIFICANCE: Since the 1990's, numerical models developed to investigate fluid flow in bone submicrometric porous network are based on the flow induced by matrix deformation. Bone fluid flow is known to be involved in cells stimulation and hence directly influences bone remodeling. Different studies have shown that intramedullary pressure is also associated with bone mechanosensitive adaptation. This pressure is developed in bone due to blood circulation and is increased during loading or muscle stimulation. The current article reviews the studies investigating the influence of this pressure on bone porous fluid flow. They show that fluid flow is involved by this pressure even without bone matrix deformation. The current review article highlights the severe lack of studies about this mechanism.

Comprehensive functional outcome analysis and importance of bone remodelling on personalized cranioplasty treatment using Poly(methyl methacrylate) bone flaps

Cranioplasty involves the surgical reconstruction of cranial defects arising as a result of various factors, including decompressive craniectomy, cranial malformations, and brain injury due to road traffic accidents. Most of the modern decompressive craniectomies (DC) warrant a future cranioplasty surgery within 6-36 months. The conventional process of capturing the defect impression and polymethyl methacrylate (PMMA) flap fabrication results in a misfit or misalignment at the site of implantation. Equally, the intra-operative graft preparation is arduous and can result in a longer surgical time, which may compromise the functional and aesthetic outcomes. As part of a multicentric pilot clinical study, we recently conducted a cohort study on ten human subjects during 2019-2022, following the human ethics committee approvals from the participating institutes. In the current study, an important aspect of measuring the extent of bone remodelling during the time gap between decompressive craniectomy and cranioplasty was successfully evaluated. The sterilised PMMA bone flaps were implanted at the defect area during the cranioplasty surgery using titanium mini plates and screws. The mean surgery time was 90 ± 20 min, comparable to the other clinical studies on cranioplasty. No signs of intra-operative and post-operative complications, such as cerebrospinal fluid leakage, hematoma, or local and systemic infection, were clinically recorded. Importantly, aesthetic outcomes were excellent for all the patients, except in a few clinical cases, wherein the PMMA bone flap was to be carefully customized due to the remodelling of the native skull bone. The extent of physiological remodelling was evaluated by superimposing the pre-operative and post-operative CT scan data after converting the defect morphology into a 3D model. This study further establishes the safety and efficacy of a technologically better approach to fabricate patient-specific acrylic bone flaps with improved surgical outcomes. More importantly, the study outcome further demonstrates the strategy to address bone remodelling during the patient-specific implant design.

Bomb pulse 14 C evidence for consistent remodeling rates of cortical femur collagen in middle-late adulthood

OBJECTIVES

Bomb pulse (BP) radiocarbon (14 C) dating methods are used by forensic anthropologists to estimate the year-of-death (YOD) of unidentified individuals. Method resolution and accuracy depend on establishing lag times, or the difference between a tissue's BP 14 C-derived year and the YOD, of various tissue types from known deceased persons. Bone lag times span many years and are thought to increase with age as a function of slowing remodeling rates. However, remodeling rates for various skeletal elements, bone structures and phases are not well known.

MATERIALS AND METHODS

Here a simple method is used to estimate bone remodeling rates from a compilation of published cortical femur bone collagen BP 14 C measurements (n = 102). Linear regression models and nonparametric tests are used to detect changes in lag times and remodeling rates with increasing age-at-death.

RESULTS

Remodeling rates and lag times of 3.5%/year and 29 years, respectively, are estimated from individuals aged 40-97 years. In contrast to previous work, the analysis yielded modest and negligible changes in remodeling rates and lag times with advancing age. Moreover, statistically significant differences in remodeling rates and lag times were not found between reported females and males.

DISCUSSION

Implications for the temporal contexts within an individual's lifetime of biogeochemical data in archaeology and forensic anthropology are discussed, warranting additional BP 14 C studies of known individuals and integration with histomorphometric analysis.

The Potential of Exosomes for Osteoporosis Treatment: A Review

As a continuous process comprising bone resorption and formation, bone remodeling, plays an essential role in maintaining the balance of bone metabolism. One type of metabolic osteopathy is osteoporosis, which is defined by low bone mass and deteriorating bone microstructure. Osteoporosis patients are more likely to experience frequent osteoporotic fractures, which makes osteoporosis prevention and treatment crucial. A growing body of research has revealed that exosomes, which are homogenous vesicles released by most cell types, play a major role in mediating a number of pathophysiological processes, including osteoporosis. Exosomes may act as a mediator in cell-to-cell communication and offer a fresh perspective on information sharing. This review discusses the characteristics of exosomes and outlines the exosomes' underlying mechanism that contributes to the onset of osteoporosis. Recent years have seen a rise in interest in the role of exosomes in osteoporosis, which has given rise to innovative therapeutic approaches for the disease prevention and management.

Recent research advances in pain mechanisms in McCune-Albright syndrome thinking about the pain mechanism of FD/MAS

BACKGROUND

The lack of effective understanding of the pain mechanism of McCune-Albright syndrome (MAS) has made the treatment of pain in this disease a difficult clinical challenge, and new therapeutic targets are urgently needed to address this dilemma.

OBJECTIVE

This paper summarizes the novel mechanisms, targets, and treatments that may produce pain in MAS and fibrous dysplasia (polyfibrous dysplasia, or FD).

METHODS

We conducted a systematic search in the PubMed database, Web of Science, China Knowledge Network (CNKI) with the following keywords: "McCune-Albright syndrome (MAS); polyfibrous dysplasia (FD); bone pain; bone remodeling; G protein coupled receptors; GDNF family receptors; purinergic receptors and glycogen synthase kinase", as well as other keywords were systematically searched. Papers published between January 2018 and May 2023 were selected for finding. Initial screening was performed by reading the titles and abstracts, and available literature was screened against the inclusion and exclusion criteria.

RESULTS

In this review, we systematically analyzed the cutting-edge advances in this disease, synthesized the findings, and discussed the differences. With regard to the complete mechanistic understanding of the pain condition in FD/MAS, in particular, we collated new findings on new pathways, neurotrophic factor receptors, purinergic receptors, interferon-stimulating factors, potassium channels, protein kinases, and corresponding hormonal modulation and their respective strengths and weaknesses.

CONCLUSION

This paper focuses on basic research to explore FD/MAS pain mechanisms. New nonneuronal and molecular mechanisms, mechanically loaded responsive neurons, and new targets for potential clinical interventions are future research directions, and a large number of animal experiments, tissue engineering techniques, and clinical trials are still needed to verify the effectiveness of the targets in the future.

Evaluation of Proximal Femoral Bone Mineral Density in Cementless Total Hip Arthroplasty: A 3-Arm Prospective Randomized Controlled Trial

BACKGROUND

Femoral stem design affects periprosthetic bone mineral density (BMD), which may impact long-term survival of cementless implants in total hip arthroplasty (THA). The aim of this study was to examine proximal femoral BMD in 3 morphologically different uncemented femoral stem designs to investigate whether any particular design resulted in better preservation of BMD.

METHODS

A total of 119 patients were randomized to receive a proximally coated collarless dual-taper wedge stem, a proximally coated collarless anatomic stem, or a fully coated collarless triple-taper stem. All surgeries were performed via the posterior approach, with mobilization on the day of surgery. Dual x-ray absorptiometry scans (Lunar iDXA, GE Healthcare) assessed BMD across the 7 Gruen zones preoperatively and at 6 weeks and 2 years postoperatively; if available, the native contralateral femur was also assessed as a control. Patient-reported outcomes of pain, function, and health were also assessed at these follow-ups.

RESULTS

Averaged across all stems, BMD increased in zones 1 (2.5%), 2 (17.1%), 3 (13.0%), 5 (10%), and 6 (17.9%) at 2 years. Greater preservation of BMD was measured on the lateral cortex (zone 2) for both the dual-taper wedge and anatomic stems (p = 0.019). The dual-taper wedge stem also demonstrated preservation of BMD in the medial calcar (zone 7), while the anatomic and triple-taper stems declined in this region; however, the difference did not reach significance (p = 0.059). Averaged across all stems, BMD decreased in the mid-diaphysis region, distal to the stem tip (zone 4). All stems performed similarly at the time of final follow-up with respect to the patient-reported outcomes.

CONCLUSIONS

This study demonstrated maintenance of femoral BMD after use of 3 different cementless femoral stem designs, with all achieving excellent improvements in patient-reported outcomes. The stems designed to load the proximal metaphyseal region resulted in higher BMD in that region. No significant stress-shielding was observed; however, longer follow-up is required to elucidate the impact of this finding on implant survivorship.

LEVEL OF EVIDENCE

Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

The critical role of toll-like receptor 4 in bone remodeling of osteoporosis: from inflammation recognition to immunity

Osteoporosis is a common chronic metabolic bone disorder. Recently, increasing numbers of studies have demonstrated that Toll-like receptor 4 (TLR4, a receptor located on the surface of osteoclasts and osteoblasts) plays a pivotal role in the development of osteoporosis. Herein, we performed a comprehensive review to summarize the findings from the relevant studies within this topic. Clinical data showed that TLR4 polymorphisms and aberrant TLR4 expression have been associated with the clinical significance of osteoporosis. Mechanistically, dysregulation of osteoblasts and osteoclasts induced by abnormal expression of TLR4 is the main molecular mechanism underlying the pathological processes of osteoporosis, which may be associated with the interactions between TLR4 and NF-κB pathway, proinflammatory effects, ncRNAs, and RUNX2. In vivo and in vitro studies demonstrate that many promising substances or agents (i.e., methionine, dioscin, miR-1906 mimic, artesunate, AEG-1 deletion, patchouli alcohol, and Bacteroides vulgatus) have been able to improve bone metabolism (i.e., inhibits bone resorption and promotes bone formation), which may partially attribute to the inhibition of TLR4 expression. The present review highlights the important role of TLR4 in the clinical significance and the pathogenesis of osteoporosis from the aspects of inflammation and immunity. Future therapeutic strategies targeting TLR4 may provide a new insight for osteoporosis treatment.

Characteristics of bone metabolism in the male patients with diabetic neuropathy

BACKGROUND

This study aimed to evaluate the characteristics of bone metabolism and fracture risk in the type 2 diabetes mellitus (T2DM) patients with distal symmetric polyneuropathy (DSPN).

METHODS

A total of 198 T2DM individuals were recruited from January 2017 to December 2020. Patients with DSPN were evaluated by strict clinical and sensory thresholds. Biochemical parameters and bone mineral density (BMD) were measured. The BMD, bone turnover markers, and probability of fracture were compared between two groups, and the factors related to BMD and probability of hip fracture in 10 years were further explored.

RESULTS

Compared with type 2 diabetes mellitus without distal symmetric polyneuropathy (T2DN-) patients, type 2 diabetes mellitus with distal symmetric polyneuropathy (T2DN+) patients had lower level of cross-linked C-telopeptide (CTX) (0.32 ± 0.19 vs 0.38 ± 0.21 ng/mL, p = 0.038) and higher level of bone-specific alkaline phosphatase (BALP) (15.28 ± 5.56 vs 12.58 ± 4.41 μg/mL, p = 0.003). T2DN+ patients had higher BMD of lumbar L1-L4 (1.05 ± 0.19 vs 0.95 ± 0.37, p = 0.027) and higher probability of hip fracture (0.98 ± 0.88 vs 0.68 ± 0.63, p = 0.009) as compared to T2DN- individuals. Univariate correlation analysis showed that BALP level (coefficient (coef) = -0.054, p = 0.038), CTX level (coef = -2.28, p = 0.001), and hip fracture risk (coef = -1.02, p < 0.001) were negatively related to the BMD of L1-L4. As for the risk of hip fracture evaluated by WHO Fracture Risk Assessment Tool (FRAX), age (coef = 0.035, p < 0.001), use of insulin (coef = 0.31, p =0.015), and levels of BALP (coef = 0.031, p = 0.017) and CTX (coef = 0.7, p = 0.047) were positively related to the risk of hip fracture. Multivariate regression analysis showed that CTX level (coef = -1.41, p = 0.043) was still negatively related to BMD at the lumbar spine.

CONCLUSION

This study indicates that T2DM patients with DSPN have special bone metabolism represented by higher BALP level and lower CTX level which may increase BMD at the lumbar spine.

Biochemical Clusters as Substitutes of Bone Biopsies in Kidney Transplant Patients

Bone and mineral metabolism abnormalities are frequent in kidney transplant recipients and have been associated with cardiovascular morbidity. The primary aim of this study was to analyse the association between routine clinically available biochemical evaluation, non-routine histomorphometric bone evaluation, and vascular disease in kidney transplanted patients. A cross-sectional analysis was performed on 69 patients, 1-year after kidney transplantation. Laboratory analysis, radiography of hands and pelvis, bone biopsy, bone densitometry, and coronary CT were performed. One-year post-transplantation, nearly one-third of the patients presented with hypercalcemia, 16% had hypophosphatemia, 39.3% had iPTH levels > 150 pg/mL, 20.3% had BALP levels > 40 U/L, and 26.1% had hypovitaminosis D. Evaluation of extraosseous calcifications revealed low Adragão and Agatston scores. We divided patients into three clusters, according to laboratory results routinely used in clinical practice: hypercalcemia and hyperparathyroidism (Cluster1); hypercalcemia and high BALP levels (Cluster2); hypophosphatemia and vitamin D deficiency (Cluster 3). Patients in clusters 1 and 2 had higher cortical porosity (p = 0.001) and osteoid measurements, although there was no difference in the presence of abnormal mineralization, or low volume. Patients in cluster 2 had a higher BFR/BS (half of the patients in cluster 2 had high bone turnover), and most patients in cluster 1 had low or normal bone turnover. Cluster 3 has no differences in volume, or turnover, but 60% of the patients presented with pre-osteomalacia. All three clusters were associated with high vascular calcifications scores. Vascular calcifications scores were not related to higher bone mineral density. Instead, an association was found between a higher Adragão score and the presence of osteoporosis at the femoral neck (p = 0.008). In conclusion, inferring bone TMV by daily clinical biochemical analysis can be misleading, and bone biopsy is important for assessing both bone turnover and mineralization after kidney transplantation, although hypophosphatemia combined with vitamin D deficiency is associated with abnormal mineralization. The presence of hypercalcemia with high levels of PTH or high levels of BALP, or hypophosphatemia and vitamin D deficiency should remind us to screen vascular calcification status of patients.Clinical Research: ClinicalTrials.gov ID NCT02751099.

Features of patients and fracture risk in hypoparathyroidism; a single center study

PURPOSE

Patients with hypoparathyroidism (hypoPT) have low bone turnover and high bone mineral density (BMD). However, data on fracture risk are conflicting. The objectives of this study were: 1. To describe clinical/biochemical characteristics of hypoPT patients followed at a single medical center. 2. To identify postsurgical hypoPT patients and investigate their fracture rate compared with gender/age-matched post-surgical normocalcemic patients.

METHODS

Retrospective analysis of patient's medical records treated at the tertiary medical center in 2010-2021 identified by computerized medical database search.

RESULTS

The cohort included 133 patients (91% women, mean age 64 ± 13 years) of whom 105 (79%) had post-thyroidectomy hypoparathyroidism and the remainder had an autoimmune/idiopathic/other etiology. Mean follow-up time was 21 ± 12 and 27 ± 12 years, respectively. The control group included 142 post-thyroidectomy patients without hypoparathyroidism. Patients in the postsurgical hypoparathyroidism group were older and had higher calcium and PTH levels at diagnosis than the non-surgical hypoPT patients. Comparing the postsurgical hypoPT and postsurgical normocalcemic control patients revealed a significantly higher BMD in the hypoPT group. Yet, fracture rates were 31% in the postsurgical hypoparathyroidism group and 21% in the control group (P = 0.1) over a similar median follow-up period (17 and 18.4 years, respectively). In both groups the most common fracture site was the spine (50% and 70%, respectively; p = 0.33), mainly nonclinical morphometric fractures. Higher phosphorus blood level was associated with increased fracture risk.

CONCLUSIONS

The relatively high BMD in patients with postsurgical hypoparathyroidism is not associated with lower fracture risk. Silent morphometric fractures are quite common in this group of patients.

Effects of bone type and occlusal loading pattern on bone remodeling in implant-supported single crown: A finite element study

PURPOSE

To assess the influence of bone types and loading patterns on the remodeling process over 12 months according to the variations in stress, strain, strain energy density (SED), and density allocation in the bone of implant-supported single crown.

MATERIALS AND METHODS

A three-dimensional finite element of a single crown implant was modeled in five different bone types (D1-D4, and grafted bone). A 200 N load was applied on an implant crown with three occlusal loading patterns (nonfunctional contact, functional contact at center, and at 2-mm offset loading). During the first 12 months after implant placement, the SED was employed as a mechanical stimulus to simulate cortical and cancellous bone remodeling.

RESULTS

Functional contact at 2-mm offset loading led to a higher bone remodeling rate and stress compared to functional contact at center and nonfunctional contact. Under 2-mm offset loading, the greatest remodeling rate after 12 months was achieved with D3 and D4, D2, grafted, and D1 cortical bone with an average peri-implant density of 1.95, 1.77, 1.56, and 1.50 g/cm3 , respectively. Meanwhile, the highest von Mises stresses were found in D4 (22.2 MPa) and D3 (21.9 MPa) bones.

CONCLUSIONS

A greater stress concentration and remodeling rate were found when an off-axial load was applied on an implant placed in low bone density. Although the fastest remodeling processes resulting in increased bone density and strength were found in D3 and D4 bone types with greater off-axial loading that may provide greater bone engagement, it could increase stress concentrations that are susceptible to inducing implant failure.

Effect of high in comparison to low dairy intake intervention on markers of bone and cartilage remodeling and phosphate metabolism in healthy adults with overweight

BACKGROUND

In the ageing population, issues with bone and joint health are highly prevalent. Both beneficial and potential risks of dairy products on bone and joint health are reported in epidemiological studies. Furthermore, the phosphorus (P) load from dairy could potentially lead to unfavorable changes in P metabolism.

OBJECTIVE

To investigate the effect of dairy intake on markers of bone and joint metabolism and P metabolism in an intervention study with high and low dairy intake.

METHODS

In a post hoc analysis of a randomized cross-over trial with overweight adults, the effect of a standardized high dairy intake [HDI (5-6 dairy portions per day) versus low dairy intake (LDI, ≤ 1 dairy portion/day)] for 6 weeks on markers of bone and joint health was assessed using enzyme-linked immunosorbent assays and electrochemiluminescence immunoassays. Markers indicative for cartilage breakdown, including urinary CTX-II, serum COMP and 4-hydroxyproline, and markers indicative for bone remodeling, such as serum CTX-I, PTH, 25(OH)D, osteocalcin, P1NP and FGF23, were investigated using linear mixed models. Furthermore, changes in P metabolism, including the main phosphate-regulating hormone FGF23 were explored.

RESULTS

This study was completed by 46 adults (57% female, age 59 ± 4 years, BMI 28 ± 2 kg/m2). Following HDI, markers such as urinary CTX-II excretion, COMP, 25(OH)D, PTH and CTX-I were significantly lower after HDI, as compared to LDI. For example, CTX-II excretion was 1688 ng/24 h at HDI, while it was 2050 ng/24 h at LDI (p < 0.001). Concurrently, P intake was higher at HDI than at LDI (2090 vs 1313 mg/day, p < 0.001). While plasma P levels did not differ (1.03 vs 1.04 mmol/L in LDI, p = 0.36), urinary P excretion was higher at HDI than at LDI (31 vs 28 mmol/L, p = 0.04). FGF23 levels tended to be higher at HDI than at LDI (76.3 vs. 72.9 RU/mL, p = 0.07).

CONCLUSIONS

HDI, as compared to LDI, reduced markers that are indicative for joint and bone resorption and bone turnover. No changes in P metabolism were observed.

CLINICAL TRIAL REGISTRY

This trial was registered at https://trialsearch.who.int/Trial2.aspx?TrialID=NTR4899 as NTR4899.

Dynamic morphometric changes in the mandibular osteocytic lacunae of ovariectomized rats in response to teriparatide, as revealed by three-dimensional fluorescence analyses: Possible involvement of osteocytic perilacunar remodeling

OBJECTIVES

Teriparatide [TPTD; human parathyroid hormone (hPTH1-34)] is an anti-osteoporotic drug with bone anabolic effects. Clinical and preclinical studies have indicated that TPTD has value in oral and maxillofacial bone therapies, including jawbone regeneration, periodontal tissue repair, and the treatment of medication-related osteonecrosis of the jaw. However, it is unclear whether the craniofacial bones respond to TPTD similarly to the axial and appendicular bones. Recent studies showed that TPTD acts on both osteocytes and osteoblasts. This study aimed to characterize distinct craniofacial bone sites, with a focus on morphometric changes in osteocytic lacunae in ovariectomized rats receiving TPTD.

METHODS

Conventional bone histomorphometric analyses of mandibular and parietal bone sections were conducted. High-resolution confocal imaging-based three-dimensional fluorescence morphometric analyses of osteocytic lacunae in distinct mandibular and parietal bone sites were conducted.

RESULTS

We observed dynamic changes in the morphometric characteristics of osteocytic lacunae specifically in alveolar and other mandibular bone sites upon TPTD administration.

CONCLUSIONS

These findings suggest that osteocytes in mandibular bone (specifically, alveolar bone) have unique functional characteristics of osteocytic perilacunar remodeling.

Topology optimization of embracing fixator considering bone remodeling to mitigate stress shielding effect

The embracing fixator is one of the widely used internal fixation implants for bone fracture treatment. However, the stress shielding effect, a stress imbalance between the implant and bone caused by the mismatch in mechanical properties between them, is a significant and critical issue that may lead to treatment failure. Thus, it is of great importance to design the implant with an appropriate stiffness which can mitigate the stress shielding effect and provide the most favorable mechanical environment for bone healing and remodeling. To this end, a time-dependent topology optimization algorithm considering bone remodeling is proposed to optimize an embracing fixator used in the tibia fracture treatment. The change of callus density over time is simulated based on a bone remodeling model, and the callus density after a period of bone remodeling is selected to be the design objective to maximize. The design constraints include volume and the compliance of the whole fixation system. Meanwhile, the influence of the constraints on the regularity of material distribution of the optimized result is also studied. Besides, to test the effectiveness of the consideration of the bone remodeling in the embracing fixator design, a topology optimization concerning the minimization of the compliance of the entire system is also performed to make a comparison. Finally, the safety performance of optimized results considering bone remodeling is also verified by static analysis.

Intracortical remodelling increases in highly loaded bone after exercise cessation

Resorption within cortices of long bones removes excess mass and damaged tissue and increases during periods of reduced mechanical loading. Returning to high-intensity exercise may place bones at risk of failure due to increased porosity caused by bone resorption. We used point-projection X-ray microscopy images of bone slices from highly loaded (metacarpal, tibia) and minimally loaded (rib) bones from 12 racehorses, 6 that died during a period of high-intensity exercise and 6 that had a period of intense exercise followed by at least 35 days of rest prior to death, and measured intracortical canal cross-sectional area (Ca.Ar) and number (N.Ca) to infer remodelling activity across sites and exercise groups. Large canals that are the consequence of bone resorption (Ca.Ar >0.04 mm2 ) were 1.4× to 18.7× greater in number and area in the third metacarpal bone from rested than exercised animals (p = 0.005-0.008), but were similar in number and area in ribs from rested and exercised animals (p = 0.575-0.688). An intermediate relationship was present in the tibia, and when large canals and smaller canals that result from partial bony infilling (Ca.Ar >0.002 mm2 ) were considered together. The mechanostat may override targeted remodelling during periods of high mechanical load by enhancing bone formation, reducing resorption and suppressing turnover. Both systems may work synergistically in rest periods to remove excess and damaged tissue.

Comparative analysis of bone turnover markers in bone marrow and peripheral blood: implications for osteoporosis

INTRODUCTION

This study examines bone turnover marker (BTM) variations between bone marrow and peripheral blood in osteoporotic and non-osteoporotic patients. BTMs offer insights into bone remodeling, crucial for understanding osteoporosis.

METHODS

A total of 133 patients were categorized into osteoporotic and non-osteoporotic cohorts. BTMs-C-telopeptide cross-linked type 1 collagen (β-CTX), serum osteocalcin (OC), Procollagen type I N-propeptide (P1NP), 25(OH)D-were measured in bone marrow and peripheral blood. Lumbar spine bone mineral density (BMD) was assessed.

RESULTS

Osteoporotic patients exhibited elevated β-CTX and OC levels in peripheral blood, indicating heightened bone resorption and turnover. β-CTX levels in osteoporotic bone marrow were significantly higher. Negative correlations were found between peripheral blood β-CTX and OC levels and lumbar spine BMD, suggesting their potential as osteoporosis severity indicators. No such correlations were observed with bone marrow markers. When analyzing postmenopausal women separately, we obtained consistent results.

CONCLUSIONS

Elevated β-CTX and OC levels in osteoporotic peripheral blood highlight their diagnostic significance. Negative β-CTX and OC-BMD correlations underscore their potential for assessing osteoporosis severity. Discrepancies between peripheral blood and bone marrow markers emphasize the need for further exploration. This research advances our understanding of BTM clinical applications in osteoporosis diagnosis and treatment.

Long-term effects of denosumab on bone mineral density and turnover markers in patients undergoing hemodialysis

INTRODUCTION

Denosumab, a fully human anti-RANKL monoclonal antibody, is a widely used osteoporosis treatment that is increasingly being used in patients undergoing dialysis; however, its long-term efficacy and safety in these patients remain unknown.

MATERIALS AND METHODS

This observational study comprised individuals aged ≥ 20 years undergoing hemodialysis and receiving denosumab. After denosumab administration, we analyzed the long-term changes in bone mineral density (BMD) and levels of bone turnover markers (BTMs) and calcium.

RESULTS

The study included 45 patients who have been receiving denosumab for a median duration of 3.8 (interquartile range, 2.5-6.7) years. Tartrate-resistant acid phosphatase 5b (TRACP-5b) levels decreased from a median of 595 (434-778) mU/dL at baseline to 200 (141-430) mU/dL after 6 months of denosumab administration (P < 0.001) and remained low thereafter. Similarly, bone-specific alkaline phosphatase (BAP) levels decreased from a median of 18.2 (15.9-25.8) μg/L at baseline to 12.4 (9.9-15.6) μg/L after 6 months (P < 0.001) and remained low thereafter. Meanwhile, BMD, as assessed with dual energy X-ray absorptiometry and measured at the distal 1/3 of the radius, did not decrease (0.465 ± 0.112 g/cm2 at baseline vs. 0.464 ± 0.112 g/cm2 after administration; P = 0.616). Regarding hypocalcemia, corrected calcium levels reached were the lowest at 7 days after administration and normalized within 30 days.

CONCLUSION

The study showed long-term suppression of TRACP-5b and BAP levels and sustaining BMD after denosumab administration over an extended period in patients undergoing hemodialysis.

Effect of Anamorelin, a Ghrelin Receptor Agonist, on Muscle and Bone in Adults With Osteosarcopenia

CONTEXT

Anamorelin, a ghrelin receptor agonist known to stimulate the pulsatile release of GH from the pituitary, has the potential to improve musculoskeletal health in adults with osteosarcopenia.

OBJECTIVE

To determine the effect of anamorelin treatment for 1 year on muscle mass and strength and on biochemical markers of bone turnover in adults with osteosarcopenia (OS).

DESIGN

Randomized, placebo-controlled, 1-year anamorelin intervention trial.

SETTING

The Bone Metabolism Laboratory at the USDA Nutrition Center at Tufts University.

PARTICIPANTS

26 men and women, age 50 years and older, with OS.

MAIN OUTCOME MEASURES

Muscle mass by D3-creatine dilution and lean body mass (LBM) and bone mineral density (BMD) by dual-energy X-ray absorptiometry, muscle strength, serum IGF-1, and bone turnover markers, serum procollagen 1 intact N-terminal (P1NP), and C-terminal telopeptide (CTX).

RESULTS

Anamorelin did not have a significant effect on muscle mass or LBM; it significantly increased knee flexion torque at 240°/s by 20% (P = .013) and had a similar nonstatistically significant effect on change in knee extension; it increased bone formation (P1NP) by 75% (P = .006) and had no significant effect on bone resorption (CTX) or BMD. Serum IGF-1 increased by 50% in the anamorelin group and did not change in the placebo group (P = .0001 for group difference).

CONCLUSION

In this pilot study, anamorelin did not significantly alter muscle mass; however, it may potentially improve lower extremity strength and bone formation in addition to increasing circulating IGF-1 levels in adults with OS. Further study of anamorelin in this population is warranted.

Effects of Multispecies Probiotic Supplementation on Serum Bone Turnover Markers in Postmenopausal Women with Osteopenia: A Randomized, Double-Blind, Placebo-Controlled Trial

Probiotics have been found to have beneficial effects on bone metabolism. In this randomized, double-blind, placebo-controlled trial, the effects of multispecies probiotic supplementation on bone turnover markers were evaluated after 12 weeks. Forty postmenopausal women with osteopenia were included and randomly divided into two groups. The intervention group received multispecies probiotics, while the control group received identical placebo sachets daily. The baseline characteristics of both groups were similar. Still, the median serum bone resorption marker C-terminal telopeptide of type I collagen (CTX) was slightly higher in the multispecies probiotic group than in the placebo group (0.35 (0.12, 0.53) vs. 0.16 (0.06, 0.75); p-value = 0.004). After 12 weeks, the mean difference in serum CTX at baseline versus 12 weeks was significantly different between the multispecies probiotic and placebo groups (-0.06 (-0.29, 0.05) vs. 0.04 (-0.45, 0.67); p-value < 0.001). The multispecies probiotic group showed a significant decrease in serum CTX at 12 weeks compared with baseline (p-value 0.026). However, the placebo group showed no significant change in serum CTX (p-value 0.18). In conclusion, multispecies probiotics may have a preventive effect on bone through their antiresorptive effect in osteopenic postmenopausal women.

Bone Remodelling, Vitamin D Status, and Lifestyle Factors in Spanish Vegans, Lacto-Ovo Vegetarians, and Omnivores

Sustainable healthy diets are promoted, and consequently vegetarian diets are currently increasing. However, scientific information on their effects on bone health is scarce. A cross-sectional study was performed in adults (66% women) classified into three groups: omnivores (n = 93), lacto-ovo vegetarians (n = 96), and vegans (n = 112). Nutrient intake, body composition, physical activity, vitamin D status (25-hydroxycholecalciferol, 25-OHD), parathormone (PTH), and bone formation (bone alkaline phosphatase, BAP) and resorption (N-telopeptides of type I collagen, NTx) markers were determined. Lacto-ovo vegetarians and especially vegans showed lower protein, fat, calcium, phosphorous, vitamin D, retinol, iodine, and zinc intakes, and higher carbohydrate, fibre, carotenes, magnesium, and vitamin K intakes compared to omnivores. Body composition was similar in the three groups that performed vigorous physical activity regularly. Body bone mass and muscle mass were positively correlated with BAP, and time performing physical activity with 25-OHD. The prevalence of vitamin D deficiency or insufficiency (25-OHD < 75 nmol/L) was 93.7% in the studied population, and vitamin D deficiency (25-OHD < 25 nmol/L) was significantly higher in vegans. Vegetarians of both groups had increased PTH and NTx with vegans showing significantly higher PTH and NTx than omnivores. Conclusion: Adult vegetarians, especially vegans, should reduce the risk of bone loss by appropriate diet planning and vitamin D supplementation.

Understanding basic multicellular unit activity in cortical bone through 3D morphological analysis: New methods to define zones of the remodeling space

The activity of basic multicellular units (BMU) in cortical bone is classically described as a sequential order of events- resorption, reversal and formation. This simplified portrayal of the remodeling process is pervasive despite the reported variability in remodeling space morphology. These variations may reflect meaningful nuances in BMU activity but methods to quantify 3D remodeling space morphology within the context of the cellular activity are currently lacking. This study developed new techniques to define zones of BMU activity based on the 3D morphology of remodeling spaces in rabbit cortical bone and integrated morphological data with the BMU longitudinal erosion rate (LER) to elucidate the spatial-temporal coordination of BMUs and estimate mineral apposition rate (MAR). The tibiae of New Zealand white rabbits (n = 5) were imaged in vivo using synchrotron radiation and two weeks later ex vivo with desktop microCT. The in vivo and ex vivo datasets were co-registered, and 27 remodeling spaces were identified at both timepoints. A radial profile representing the 3D morphology was the platform for partitioning the remodeling spaces into resorption, reversal and formation zones. Manual, automated and semi-automated partitioning approaches were compared, and the zone-segmentations were used to calculate the length, change in radius and slope of each zone. The manual approach most accurately defined the zones of idealized remodeling spaces with known dimensions (relative error = 0.9-9.2 %) while the semi-automated method reliably defined the zones in rabbit remodeling spaces (ICC = 0.85-1.00). Combining LER and the manually derived zone dimensions indicated that a BMU passes through a cross-section in approximately 18.8 days with resorption, reversal and formation taking 4.1, 2.2, and 12.5 days, respectively. MAR estimated by the 3D analysis was not significantly different than that determined with classic histomorphometry (p = 0.48). These techniques have the potential to assess dynamic parameters of bone resorption and formation, eliminate the need for fluorochrome labeling and provide a more comprehensive perspective of the remodeling process.

Osteoprotegerin and receptor activator of the nuclear factor kappa B ligand (RANKL) in healthy pubertal girls - relationships with physical growth and classical bone turnover markers

Osteoprotegerin (OPG) is a trap receptor for the receptor activator of the nuclear factor kappa B ligand (RANKL). We aimed to determine the OPG and free soluble RANKL (sRANKL) concentrations in girls during puberty and their relationships with pubertal stage, growth rate and serum concentrations of estradiol, as well as classical bone formation (N-terminal propeptide of type I collagen (PINP), bone-specific alkaline phosphatase (BALP), osteocalcin (OC)) and bone resorption (C-terminal telopeptide of type I collagen (CTX)) markers. The semi-longitudinal study involved 88 healthy girls, aged 11.8-13.2 years. Their weight and height were measured twice at one-year intervals. Pubertal stages were assessed using the Tanner (T) scale. Blood samples were taken at the first examination. Serum concentrations of OPG, sRANKL, CTX and BALP were determined by enzyme-linked immunosorbent assay, estradiol and PINP by radioimmunoassay and osteocalcin by immunoradiometric assay. The one-year increase in height and weight of girls in the T2 and T3 pubertal stages was greater than that of girls in the T4 stage (p=0.000, p<0.03). OPG concentrations (T2: 4.04±0.62; T3: 4.31±0.79; T4: 4.46±0.84 pmol/L) sRANKL concentrations (T2: 0.22 (IQR 0.09-0.54); T3: 0.42 (IQR 0.22-0.79); T4: 0.35 (IQR 0.16-1.04) pmol/L) and sRANKL/OPG ratios (T2: 0.05 (IQR 0.03-0.13); T3: 0.11 (IQR 0.05-0.19); T4: 0.09 (IQR 0.05-0.19) did not differ significantly between pubertal stages. Concentrations of PINP, CTX, BALP and OC were higher in girls at T3 stage than at the T4 stage (p=0.000, p=0.001, p=0.046, p=0.038; respectively). Concentrations of sRANKL and OPG did not correlate with body weight, height, growth rate, or concentrations of estradiol, PINP, CTX, BALP and OC. There were correlations between the increase in height over one year and the concentrations of PINP (r=0.499, p=0.000), CTX (r=0.311, p=0.003) and BALP (r=0.224, p=0.036), as well as of estradiol (r=-0.473, p=0.000). Unlike PINP, OC, BALP, CTX or estradiol concentrations, sRANKL and OPG concentrations do not change in girls during puberty. Neither OPG nor sRANKL concentrations correlate with somatic characteristics and classical bone turnover markers concentrations.

Serum Markers of Bone Turnover Following Controlled Administration of Two Medical Cannabis Products in Healthy Adults

Introduction: Cannabidiol (CBD) has been shown to maintain bone integrity in pre-clinical models, but little is known about the effects of delta-9-tetrahydrocannabinol (THC) on bone turnover. In this study we explored the effects of two oral medical cannabis products on normal bone homeostasis through evaluation of markers of bone resorption (carboxyl-terminal collagen crosslinks, CTx) and bone formation (procollagen type 1 N-terminal propeptide, P1NP; alkaline phosphatase, ALP). Methods: This study is an analysis of secondary data from two Phase 1 double-blind, placebo-controlled trials of Spectrum Yellow (0.9 mg THC, 20 mg CBD/mL of oil) and Spectrum Red (2.5 mg THC, 0.3 mg CBD/softgel). Healthy participants (n=38 men, 45 women) were randomized to receive 5-20 mg THC (CBD levels varied as a function of administered product) or placebo daily (BID) for 7 days. Bone markers were assessed at baseline, upon completion of product administration (day 8), and after a 5-day washout (day 13). Results: All bone markers were significantly higher in men at baseline (p≤0.008). For CTx, there was a significant day×group interaction (F=3.23, p=0.04); CTx levels were significantly lower in participants treated with Spectrum Red (b=-164.28; 95% confidence interval [CI], -328 to -0.29; p=0.04) and marginally lower in participants treated with Spectrum Yellow (b=-157.31; 95% CI, -323 to 8.68; p=0.06) versus placebo on day 8. For P1NP and ALP, there were no significant differences between treatments across study days. Bone marker values outside the reference range (RR) were observed; CTx > RR (n=71) was predominantly (85.9%) observed in male participants, whereas P1NP > RR (n=100) was more evenly distributed between sexes (53.0% in men). These were not considered clinically significant and did not differ between treatment groups. Conclusions: These are the first interventional human data on the effect of cannabinoids on biomarkers of bone turnover. Short-term treatment with CBD- or THC-dominant medical cannabis products resulted in attenuation of a marker of bone resorption. Although the attenuation was not clinically significant, this finding may be indicative of protective properties of cannabinoids in bone. Further research over longer dosing durations in individuals exhibiting bone-specific conditions (e.g., osteoporosis) is warranted. ClinicalTrials.gov IDs: ACTRN12619001723178 and ACTRN12619001450101.

Effect of occlusal stabilisation splint with or without arthroscopic disc repositioning on condylar bone remodelling in adolescent patients

The aim of this study was to investigate the treatment effects of a stabilisation splint (SS) with and without arthroscopic disc repositioning (ADR) on condylar bone remodelling in adolescent patients with anterior disc displacement without reduction (ADDwoR). Cone beam computed tomography and magnetic resonance imaging were used to analyse condylar bone remodelling, condyle position, and disc position. Twenty-two temporomandibular joints of 14 patients who underwent ADR (age range 12-20 years; mean follow-up 12.5 ± 7.8 months) and 21 temporomandibular joints of 14 patients who did not undergo ADR (age range 13-20 years; mean follow-up 11.1 ± 5.1 months) were included. The change in bone volume (P < 0.001), rate of bone volume change (P < 0.001), and change in condyle height (P = 0.031) were significantly greater in patients with ADR than in those without ADR. The changes in posterior joint space (P = 0.013), superior joint space (P = 0.020), and ratio of condyle sagittal position (P = 0.013) were significantly greater in patients with ADR than in those without ADR. All discs in patients who underwent ADR and one disc in those who did not undergo ADR were backward repositioned. In conclusion, in adolescent patients with ADDwoR, ADR with SS therapy achieved better condyle and disc position than SS therapy alone, and also induced bone generation.

Cytokines: The links between bone and the immune system

Osteoporosis results from an imbalance in a highly balanced physiological process called bone remodeling, in which osteoclast-mediated bone resorption and osteoblast-mediated bone formation play important roles. Osteoimmunology is a newly discovered interdisciplinary research field that focuses on the relationship between bone and the immune system. Specifically, bone and the immune system interact through cytokines, immune cells secrete cytokines, and cytokines finely regulate bone metabolism by mediating the differentiation and activity of osteoclasts and osteoblasts. Therefore, understanding the influence of cytokines on bone metabolism is conducive for the development of novel targeted drugs against immune-related bone diseases. This review summarizes the pathophysiological functions of various common cytokines in bone and discusses the potential clinical value of multiple cytokines in immune-mediated bone diseases.

Callus formation and bone remodeling in a tibial nonunion after minimal invasive percutaneous screw fixation followed by extracorporeal shockwave therapy 17-months after initial trauma - A case report

INTRODUCTION

The treatment of tibial nonunion is challenging and treatment may be conservative or surgical. Conservative strategies include functional braces and weight bearing, or focused extracorporeal shockwave therapy (fESWT).

CASE DESCRIPTION

A 45-year-old male patient sustained spiral tibial shaft fractures and was treated surgically within 24 hours after the initial accident with intramedullary nails. The tibial fracture was later classified as nonunion after 11 months. Radiologic evaluation 17 months after the initial trauma demonstrated clinical nonunion, and subsequently the patient was offered a conservative approach with fESWT to facilitate an increase in callus formation. The handpiece was fitted with a stand-off II (long), penetration depth of 15 mm. Three cycles were administered in month 17, 19 and 20 after baseline. Each cycle consisted of three treatments sessions spaced with 6-8 days apart, and consisted of 3000 to 4000 impulses each given at 0.25-0.84 mJ/mm2. The number of impulses and the power at the focus point varied according to the pain response.

OUTCOMES

The patient achieved union 23 months after fracture. A clinical important improvement was observed with both Lower Extremity Functional Scale (LEFS) (18-point difference) and Patient Specific Functional Scale (PSFS) (average: 4.7 points,) The "worst pain last 24 hours" was reduced by 5 points. These values express minimal clinically important difference (MCID) values in these functional patient-reported outcome measures.

CONCLUSION

This treatment strategy may be viable in a broader setting, including private practice physiotherapy thereby treating the patient in close proximity to the patient's everyday life.

Three-dimensional bone remodelling of glenoid fossa in patients with skeletal Class III malocclusion after bimaxillary orthognathic surgery

This study aimed to characterize three-dimensional quantitative morphological changes of glenoid fossa in patients with skeletal Class III malocclusion treated with bimaxillary orthognathic surgery. Ninety-five eligible patients (50 male, 45 female; mean age 22.09 years) were enrolled retrospectively. Cone beam computed tomography obtained at 1 week preoperatively (T0), immediately after surgery (T1), and at ≥ 12 months postoperatively (T2) were registered based on cranial base using voxel-based registration in 3D Slicer. Glenoid fossa surface was divided spatially into four regions, and bone modelling in these regions was visualized with color maps. Our data revealed that the mean surface variations of glenoid fossa were small, with modest bone formation as a whole. No significant associations between anteroposterior or vertical mandibular displacement and overall glenoid fossa remodeling were found (P > 0.05). Moreover, bone deposition was frequently observed in the anterior-lateral region of glenoid fossa in patients with a larger mandibular movement during T0-T1 (P < 0.001). Paired bone formation in the anterior-lateral region of glenoid fossa and bone resorption in the anterior-lateral region of condylar head was frequently observed. Collectively, our results revealed that glenoid fossa underwent complex but modest bone remodeling after bimaxillary surgery in skeletal Class III patients.

Macrophage Activation in Synovitis and Osteoarthritis of Temporomandibular Joint and Its Relationship with the Progression of Synovitis and Bone Remodeling

This study investigates the regulatory mechanisms of synovial macrophages and their polarization in the progression of temporomandibular joint osteoarthritis (TMJOA). Macrophage depletion models were established by intra-articular injection of clodronate liposomes and unloaded liposomes. TMJOA was induced by intra-articular injection of 50 μL Complete Freund's Adjuvant and the surgery of disc perforation. The contralateral joint was used as the control group. The expression of F4/80, CD86, and CD206 in the synovium was detected by immunofluorescence staining analysis. Hematoxylin and eosin staining and TMJOA synovial score were detected to show the synovial changes in rat joints after TMJOA induction and macrophage depletion. Changes in rat cartilage after TMJOA induction and macrophage depletion were shown by safranin fast green staining. The bone-related parameters of rats' joints were evaluated by micro-computed tomography analysis. The TMJOA model induced by Complete Freund's Adjuvant injection and disc perforation aggravated synovial hyperplasia and showed a significant up-regulation of expression of F4/80-, CD86-, and CD206-positive cells. F4/80, CD86, and CD206 staining levels were significantly decreased in macrophage depletion rats, whereas the synovitis score further increased and cartilage and subchondral bone destruction was slightly aggravated. Macrophages were crucially involved in the progression of TMJOA, and macrophage depletion in TMJOA synoviocytes promoted synovitis and cartilage destruction.

The impact of antiseizure medication on bone heath: A systematic review of animal studies

BACKGROUND

Antiseizure medications (ASMs) are known to potentially impact bone health, but existing literature presents conflicting results regarding their specific effects on bone mineralization, metabolism, and quality.

OBJECTIVE

This systematic review aims to establish a consensus regarding the influence of ASMs on bone health based on existing preclinical studies.

METHODS

Following SYRCLE and PRISMA guidelines, we conducted a systematic search in PubMed, Science Direct, and Google Scholar to identify relevant studies. Ultimately, 21 articles were selected for inclusion in this review.

RESULTS

Among the chosen studies, approximately half involved Wistar rats as experimental subjects. Levetiracetam and sodium valproate were the most frequently investigated drugs, with a typical treatment duration of 10-12 weeks. These studies exhibited a low risk of bias in aspects like sequence generation, random housing, random outcome assessment, and reporting bias. However, blinding in performance, allocation concealment, and detection were often rated as having a high risk of bias. The collective findings suggest that prolonged ASM use leads to reduced bone mineral density, altered bone turnover marker levels (including hypovitaminosis D, hypocalcemia, and secondary hyperparathyroidism), deterioration of bone microarchitecture, and decreased mechanical strength.

CONCLUSION

The adverse effects on bone associated with ASMs are not limited to enzyme-inducing drugs, as newer generation ASMs may also contribute to these effects. Hypovitaminosis D alone may not be solely responsible for ASM-induced bone issues, suggesting the involvement of other mechanisms. Furthermore, substantial variations were observed in the results of different preclinical studies on individual ASMs, highlighting the need to standardize animal study methodologies to enhance reproducibility and reduce variation.

Sleep characteristics and parameters of bone turnover and strength in the adult population: results from the Study of Health in Pomerania-TREND

Poor sleep quality or sleep deprivation may be related to decreased bone mineral density. We aimed to assess whether associations of sleep characteristics and bone turnover or strength are present in adults from the general population and whether these are independent of common risk factors such as sex, age, and obesity. A total of 1037 participants from the Study of Health in Pomerania-TREND underwent laboratory-based polysomnography and quantitative ultrasound measurements at the heel. Of these participants, 804 completed standardised questionnaires to assess daytime sleepiness, insomnia, and sleep quality. Serum concentrations of two bone turnover markers, intact amino-terminal propeptide of type 1 procollagen (P1NP) and carboxy-terminal telopeptide of type 1 collagen (CTX) were measured. Cross-sectional associations of polysomnography variables (total sleep time, sleep efficiency, time spent wake after sleep onset, oxygen desaturation index, apnea-hypopnea index, and obstructive sleep apnea [OSA]), as well as sleep questionnaire scores with the bone turnover markers and the ultrasound-based stiffness index were assessed in linear regression models. In adjusted models, higher insomnia scores and lower sleep quality scores were related to a higher bone turnover in women but not in men. However, associations between polysomnography variables or questionnaire scores and the stiffness index were absent. Our study provides limited evidence for relationships between sleep characteristics and bone turnover and strength independent of common risk factors for OSA and osteoporosis. Nevertheless, women reporting poor sleep or insomnia in combination with risk factors for osteoporosis might benefit from an evaluation of bone health.

The Role of Osteocytes in Pre-metastatic Niche Formation

PURPOSE OF REVIEW

The formation of a pre-metastatic niche (PMN), in which primary cancer cells prime the distant site to be favorable to their engraftment and survival, may help explain the strong osteotropism observed in multiple cancers, such as breast and prostate. PMN formation, which includes extracellular matrix remodeling, increased angiogenesis and vascular permeability, enhanced bone marrow-derived cell recruitment and immune suppression, has mostly been described in soft tissues. In this review, we summarize current literature of PMN formation in bone. We also present evidence of a potential role for osteocytes to be the primary mediators of PMN development.

RECENT FINDINGS

Osteocytes regulate the bone microenvironment in myriad ways beyond canonical bone tissue remodeling, including changes that contribute to PMN formation. Perilacunar tissue remodeling, which has been observed in both bone and non-bone metastatic cancers, is a potential mechanism by which osteocyte-cancer cell signaling stimulates changes to the bone microenvironment. Osteocytes also protect against endothelial permeability, including that induced by cancer cells, in a loading-mediated process. Finally, osteocytes are potent regulators of cells within the bone marrow, including progenitors and immune cells, and might be involved in this aspect of PMN formation. Osteocytes should be examined for their role in PMN formation.

Effect of acute resistance exercise on bone turnover in young adults before and after concurrent resistance and interval training

Weight-bearing physical activity can stimulate bone adaptation. This investigation explored the effect of an acute bout of resistance exercise before and after resistance+interval training on circulating biomarkers of bone metabolism and muscle-bone crosstalk. Healthy young male and female participants (n = 21 male, 28 ± 4 years; n = 17 female, 27 ± 5 years) performed a 6 × 10 squat test (75% 1RM) before and after a 12-week resistance+interval training program. Before and after completion of the training program, blood samples were collected at rest, immediately postexercise, and 2 h postexercise. Blood samples were analyzed for βCTX, P1NP, sclerostin, osteocalcin, IGF-1, and irisin. Significant effects of acute exercise (main effect of time) were observed as increases in concentrations of IGF-1, irisin, osteocalcin, and P1NP from rest to postexercise. A sex*time interaction indicated a greater decline in βCTX concentration from rest to 2 h postexercise and a greater increase in sclerostin concentration from rest to immediately postexercise in male compared with female participants. Sex differences (main effect of sex) were also observed for irisin and P1NP concentrations. In summary, changes in concentrations of biochemical markers of bone metabolism and muscle-bone crosstalk were observed in males and females after an acute bout of resistance exercise and following 12 weeks of resistance+interval training.

Clinical application of bone turnover markers in osteoporosis

Bone turnover markers (BTM) are highly responsive to initiation and changes in anti-osteoporotic therapy. In contrast to the slow treatment-induced changes in bone mineral density, the fast changes in BTM enable the clinician to adjust treatment management within a short timeframe. This review describes how BTM can be used for treatment monitoring, including monitoring during discontinuation of alendronate and denosumab therapy. In addition, sources of errors and pitfalls when using BTM monitoring will be described.

A pilot feasibility randomised controlled trial of bone antiresorptive agents on bone turnover markers in critically ill women

Critical illness is associated with increased bone turnover, loss of bone density, and increased risk of fragility fractures. The impact of bone antiresorptive agents in this population is not established. This trial examined the efficacy, feasibility, and safety of antiresorptive agents administered to critically ill women aged fifty years or greater. Women aged 50 years or greater admitted to an intensive care unit for at least 24 h were randomised to receive an antiresorptive agent (zoledronic acid or denosumab) or placebo, during critical illness and six months later (denosumab only). Bone turnover markers and bone mineral density (BMD) were monitored for 1 year. We studied 18 patients over 35 months before stopping the study due to the COVID-19 pandemic. Antiresorptive medications decreased the bone turnover marker type 1 cross-linked c-telopeptide (CTX) from day 0 to 28 by 43% (± 40%), compared to an increase of 26% (± 55%) observed with placebo (absolute difference - 69%, 95% CI - 127% to - 11%), p = 0.03). Mixed linear modelling revealed differences in the month after trial drug administration between the groups in serum CTX, alkaline phosphatase, parathyroid hormone, and phosphate. Change in BMD between antiresorptive and placebo groups was not statistically analysed due to small numbers. No serious adverse events were recorded. In critically ill women aged 50-years and over, antiresorptive agents suppressed bone resorption markers without serious adverse events. However, recruitment was slow. Further phase 2 trials examining the efficacy of these agents are warranted and should address barriers to enrolment.Trial registration: ACTRN12617000545369, registered 18th April 2017.

[Advances in Molecular Regulatory Mechanisms of Jaw Repair and Reconstruction]

Jawbone injuries resulting from trauma, diseases, and surgical resections are commonly seen in clinical practice, necessitating precise and effective strategies for repair and reconstruction to restore both function and aesthetics. The precise and effective repair and the reconstruction of jawbone injuries pose a significant challenge in the field of oral and maxillofacial surgery, owing to the unique biomechanical characteristics and physiological functions of the jawbone. The natural repair process following jawbone injuries involves stages such as hematoma formation, inflammatory response, ossification, and bone remodeling. Bone morphogenetic proteins (BMPs), transforming growth factor beta (TGF-β), vascular endothelial growth factor (VEGF), and other growth factors play crucial roles in promoting jawbone regeneration. Cytokines such as interleukins and tumor necrosis factor play dual roles in regulating inflammatory response and bone repair. In recent years, significant progress in molecular biology research has been made in the field of jawbone repair and reconstruction. Tissue engineering technologies, including stem cell therapy, bioactive scaffolds, and growth factor delivery systems, have found important applications in jawbone repair. However, the intricate molecular regulatory mechanisms involved in the complex jawbone repair and reconstruction methods are not fully understood and still require further research. Future research directions will be focused on the precise control of these molecular processes and the development of more efficient combination therapeutic strategies to promote the effective and functional reconstruction of the jawbone. This review aims to examine the latest findings on the molecular regulatory mechanisms of the repair and reconstruction of jawbone injuries and the therapeutic strategies. The conclusions drawn in this article provide a molecular-level understanding of the repair of jawbone injuries and highlight potential directions for future research.

Sema3A secreted by sensory nerve induces bone formation under mechanical loads

Bone formation and deposition are initiated by sensory nerve infiltration in adaptive bone remodeling. Here, we focused on the role of Semaphorin 3A (Sema3A), expressed by sensory nerves, in mechanical loads-induced bone formation and nerve withdrawal using orthodontic tooth movement (OTM) model. Firstly, bone formation was activated after the 3rd day of OTM, coinciding with a decrease in sensory nerves and an increase in pain threshold. Sema3A, rather than nerve growth factor (NGF), highly expressed in both trigeminal ganglion and the axons of periodontal ligament following the 3rd day of OTM. Moreover, in vitro mechanical loads upregulated Sema3A in neurons instead of in human periodontal ligament cells (hPDLCs) within 24 hours. Furthermore, exogenous Sema3A restored the suppressed alveolar bone formation and the osteogenic differentiation of hPDLCs induced by mechanical overload. Mechanistically, Sema3A prevented overstretching of F-actin induced by mechanical overload through ROCK2 pathway, maintaining mitochondrial dynamics as mitochondrial fusion. Therefore, Sema3A exhibits dual therapeutic effects in mechanical loads-induced bone formation, both as a pain-sensitive analgesic and a positive regulator for bone formation.

Age estimation in the combined long bones and ribs by histomorphometry: Past, present, and future

Numerous age estimation methods in unidentified bone have been a long time developing for application in forensic anthropology. The histomorphometric technique is one of the alternative methods that relied upon the evaluation of the cortical bone microstructure over the lifespan as a result of the remodeling process in bone. Remodeling is a sophisticated event occurring from the coupled function of bone formation and resorption cells for maintaining mineral homeostasis and repairment of microdamage in bone tissue. Products derived from remodeling are primary changes in the osteon or haversian system in various regions in the cortical bone, including periosteum, endosteum, and trabecular bone. Throughout life, bone remodeling rate with osteon alteration can be predictable. In the forensic field, histological methods are getting more attention due to the unavailability of macroscopic methods. Histomorphometry approach can be accomplished in fragmentary or incomplete bone remains indicating the limited use of gross morphological methods. In addition, the microscopic methods can aid to increase the more accuracy of analyses and diminish the biased subjective assessment for determining age. Most histomorphometry method utilizes a cross-section of the midshaft of the long bones including the mandible, rib, and clavicle. This review provides the basic knowledge of bone biology and anatomy, several age-estimating methods of histology, and crucial factors for age methods. Studies regarding overall age determination methods from the past until now contribute to obtaining more benefits for developing methods of histomorphometry using human bone in forensic identification.