Influence of mucosal tissue height on implant crestal bone: A 10-year follow-up of a controlled clinical trial.

OBJECTIVE: To evaluate the 10-year influence of soft tissue height (STH) on crestal bone level changes (CBC) in bone-level implants with non-matching internal conical connections. MATERIAL & METHODS: From the initial 97 patients, 59 (19 men, 40 women, age 55.86 ± 9.5 years) returned for the recall visit. Based on baseline STH, they were categorized into T1 (thin STH ≤2 mm, n = 33), T2 (thin STH augmented with allogenic tissue matrix (ATM), n = 32), and C (thick STH >2mm, n = 32). Implants were placed in the posterior mandible using a one-stage approach and received single screw-retained restorations. Clinical (PPD, BOP, PI) and radiographic examinations were conducted after 10 years, with CBC calculated mesial and distal to each implant. RESULTS: After 10 years, implants in surgically thickened (T2) or naturally thick STH (C) showed bone gains of 0.57 ± 0.55mm and 0.56 ± 0.40mm, respectively (p < 0.0001) shifting from an initial CBC of -0.21 ± 0.33 mm to 0.36 ± 0.29 mm in the thick STH group and -0.2 ± 0.35 mm to 0.37 ± 0.29 mm in the surgically thickened STH group after 10 years. Implants in naturally thin STH yielded a non-significant trend of bone loss (-0.12 ± 0.41mm; p > 0.05). CONCLUSIONS: Implants in thin STH (≤2 mm) exhibited greater CBC over the study period. Significant bone gains were observed in thick STH cases, indicating that naturally thick STH or STH augmentation with ATM and may contribute to maintaining CBC in long-term around implants. CLINICAL SIGNIFICANCE: This is the first long-term follow-up study suggesting that adequate soft tissue height around implants helps maintain stable peri-implant bone levels. While tissue thickness plays a key role, other factors also interact with peri-implant tissue height to sustain crestal bone stability over time.

Exogenous iron caused osteocyte apoptosis, increased RANKL production, and stimulated bone resorption through oxidative stress in a murine model.

Iron overload is a risk factor for osteoporosis due to its oxidative toxicity. Previous studies have demonstrated that an excessive amount of iron increases osteocyte apoptosis and receptor activator of nuclear factor κ-B ligand (RANKL) production, which stimulates osteoclast differentiation in vitro. However, the effects of exogenous iron supplementation-induced iron overload on osteocytes in vivo and its role in iron overload-induced bone loss are unknown. This work aimed to develop an iron overloaded murine model of C57BL/6 mice by intraperitoneal administration of iron dextran for two months. The iron levels in various organs, bone, and serum, as well as the microstructure and strength of bone, apoptosis of osteocytes, oxidative stress in bone tissue, and bone formation and resorption, were assessed. The results showed that 2 months of exogenous iron supplementation significantly increased iron levels in the liver, spleen, kidney, bone tissue, and serum. Iron overload negatively affected bone microstructure and strength. Osteocyte apoptosis and empty lacunae rate were elevated by exogenous iron. Iron overload upregulated RANKL expression but had no significant impact on osteoprotegerin (OPG) and sclerostin levels. Static and dynamic histologic analyses and serum biochemical assay showed that iron overload increased bone resorption without significantly affecting bone formation. Exogenous iron promoted oxidative stress in osteocytes in vivo and in vitro. Additional supplementation of iron chelator (deferoxamine) or N-acetyl-L-cysteine (NAC) partially alleviated bone loss, osteocyte apoptosis, osteoclast formation, and oxidative stress due to iron overload. These findings, in line with prior in vitro studies, suggest that exogenous iron supplementation induces osteoclastogenesis and osteoporosis by promoting osteocyte apoptosis and RANKL production via oxidative stress.

Effect of Cells Derived from Periodontal Ligament Tissue on Bone Formation.

BACKGROUND/AIM: Recent reports indicate that sclerostin is secreted by periodontal ligament tissue-derived (PDL) cells during orthodontic force loading and that the secreted sclerostin contributes to bone metabolism. However, the detailed mechanism is poorly understood. The aim of this study was to determine how PDL cells affect bone formation. MATERIALS AND METHODS: Rat periodontal ligament tissue was immunohistochemically stained for sclerostin. Cultured primary PDL cells, osteoblasts, and skin fibroblasts (Sfbs) isolated from rat periodontal ligament tissue, calvaria, and skin, respectively, were examined. Osteoblasts were cultured with control conditioned medium (Cont-CDM) and PDL cell culture conditioned medium (PDL-CDM) for up to 21 days. Cultured osteoblasts were then stained with alkaline phosphatase and von Kossa stain. Osteoblasts cultured in each conditioned medium were analyzed by real-time quantitative PCR for bone Gla protein (Bgp), Axin2, and Ki67 expression. PDL cells used to obtain conditioned medium were analyzed for Sost, Ectodin and Wnt1 expression and compared with expression in Sfbs. RESULTS: Expression of sclerostin was observed in periodontal ligament tissue by immunohistochemical staining. The formation of mineralization nodules was inhibited in PDL-CDM compared with Cont-CDM in osteoblast culture. In PDL-CDM, the expression levels of Bgp and Axin2 in osteoblasts were decreased compared with Cont-CDM. In PDL cells, expression levels of Sost and Ectodin were much higher than in Sfbs; however, expression of Wnt1 was lower in PDL cells compared with Sfbs. CONCLUSION: PDL cells secrete various proteins, including sclerostin and suppress osteogenesis in osteoblasts through the canonical Wnt pathway.

The high-bone-mass phenotype of novel transgenic mice with LRP5 A241T mutation.

Gain-of-function mutations in the low-density lipoprotein receptor-related protein 5 (LRP5) can cause high-bone-mass (HBM) phenotype, with 19 identified mutations so far. The A242T mutation in LRP5 has been found in 9 families, making it one of the most prevalent mutations. However, the correlation between the A242T mutation and HBM phenotype remains unverified in animal models. This study aimed to investigate the bone properties in a new transgenic mouse model carrying the LRP5 A241T missense mutation, equivalent to A242T in humans. Heterozygous Lrp5A241T mice were generated using CRISPR/Cas9 genome editing. Body weight increased with age from 4 to 16 weeks, higher in males than females, with no difference between Lrp5A241T mice and wild-type control. Micro-CT showed slightly longer femur and notably elevated trabecular bone mass of the femur and fifth lumbar spine with higher bone mineral density, bone volume fraction, and trabecular thickness in Lrp5A241T mice compared to wild-type mice. Additionally, increased cortical bone thickness and volume of the femur shaft and skull were observed in Lrp5A241T mice. Three-point bending tests of the tibia demonstrated enhanced bone strength properties in Lrp5A241T mice. Histomorphometry confirmed that the A241T mutation increased bone formation without affecting osteoblast number and reduced resorption activities in vivo. In vitro experiments indicated that the LRP5 A241T mutation enhanced osteogenic capacity of osteoblasts with upregulation of the Wnt signaling pathway, with no significant impact on the resorptive activity of osteoclasts. In summary, mice carrying the LRP5 A241T mutation displayed high bone mass and quality due to enhanced bone formation and reduced bone resorption in vivo, potentially mediated by the augmented osteogenic potential of osteoblasts. Continued investigation into the regulatory mechanisms of its bone metabolism and homeostasis may contribute to the advancement of novel therapeutic strategies for bone disorders.

UBE2C orchestrates bone formation through stabilization of SMAD1/5.

While previous studies have demonstrated the role of ubiquitin-conjugating enzyme 2C (UBE2C) in promoting ß-cell proliferation and cancer cell lineage expansion, its specific function and mechanism in bone marrow mesenchymal stem/stromal cells (BMSCs) growth and differentiation remain poorly understood. Our findings indicate that mice with conditional Ube2c deletions in BMSCs and osteoblasts exhibit reduced skeletal bone mass and impaired bone repair. A significant reduction in the proliferative capacity of BMSCs was observed in conditional Ube2c knockout mice, with no effect on apoptosis. Additionally, conditional Ube2c knockout mice exhibited enhanced osteoclastic activity and reduced osteogenic differentiation. Furthermore, human BMSCs with stable UBE2C knockdown exhibited diminished capacity for osteogenic differentiation. Mechanistically, we discovered that UBE2C binds to and stabilizes SMAD1/5 protein expression levels. Interestingly, UBE2C's role in regulating osteogenic differentiation and SMAD1/5 expression levels appears to be independent of its enzymatic activity. Notably, UBE2C regulates osteogenic differentiation through SMAD1/5 signaling. In conclusion, our findings underscore the pivotal role of UBE2C in bone formation, emphasizing its contribution to enhanced osteogenic differentiation through the stabilization of SMAD1/5. These results propose UBE2C as a promising target for BMSC-based bone regeneration.

Sinusoidal alternating electromagnetic field accelerates fracture healing in rats. / æ­£å¼¦äº¤å˜ç”µç£åœºå¯åŠ é€Ÿå¤§é¼ éª¨æŠ˜æ„ˆåˆ.

OBJECTIVES: To investigate the effect of sinusoidal alternating electromagnetic field (SEMF) on fracture healing and its mechanism. METHODS: Femoral fracture model was established using SPF male Wistar rats, 30 model rats were randomly divided into model control (MC) and SEMF groups with 15 rats in each group. The SEMF group was given 50 Hz 1.8 mT for 90 min every day, and the MC group was not treated. X-ray examinations were performed every two weeks to determine the formation of bone scabs in each group of rats. Three rats were sacrificed after 2 and 4 weeks of treatment in both groups. Protein was extracted from the fractured femurs, and the expression of type Ⅰ collagen (COL-1), Osterix (OSX), Runt-related transcription factor 2 (RUNX2), and vascular endothelial growth factor (VEGF) protein level was detected by immunoblotting. After 8 weeks, the femur on the operated side was taken for micro-CT scanning to observe fracture healing, angiography to observe blood vessel growth, and organs such as hearts, livers, spleens, lungs, and kidneys were taken for safety evaluation by hematoxylin-eosin staining (HE staining). RESULTS: The bone scab scores of the SEMF group were significantly higher than those of the MC group after 2, 4, 6, and 8 weeks of treatment (all P<0.01); the fracture healing of the SEMF group was better than that of the MC group after 8 weeks, and the bone volume scores of the two groups were 0.243±0.012 and 0.186±0.008, respectively, with statistically significant differences (P<0.01); and the number of blood vessels in the SEMF group was also more than that of the MC group after 8 weeks. The results of protein blotting method showed that the protein expression of VEGF, COL-1, RUNX2, and OSX was higher in the SEMF group than in the MC group after 2 and 4 weeks of treatment (all P<0.05), and the HE staining showed that there was no abnormality in histopathological observation of examined organs in both groups. CONCLUSIONS: SEMF can accelerate fracture healing by promoting the expression of osteogenic factors and vascular proliferation without significant adverse effects.

Disease-specific definitions of new bone formation on spine radiographs: a systematic literature review.

Objectives: We aimed to explore the radiographic definitions of types of New Bone formation (NBF) by focusing on the terminology, description and location of the findings. Methods: Three systematic literature reviews were conducted in parallel to identify the radiographic spinal NBF definitions for spondyloarthritis (SpA), Diffuse Idiopathic Skeletal Hyperostosis (DISH) and Osteorathritis (OA). Study characteristics and definitions were extracted independently by two reviewers. Definitions were analysed and collated based on whether they were unique, modified or established from previous research. Results: We identified 33 studies that indicated a definition for the NBF in SpA, 10 for DISH and 7 for spinal OA. In SpA, the variations in syndesmophytes included the description as well as the subtypes and locations. The differentiation of syndesmophytes from osteophytes were included in 12 articles, based on the origin and the angle of the NBF and associated findings. The definitions of DISH varied in the number of vertebrae, level and laterality. For OA, five articles indicated that osteophytes arose from the anterior or lateral aspects of the vertebral bodies, and two studies required a size cut-off. Discussion: Our ultimate aim is to create formal NBF definitions for SpA, DISH and OA guided by an atlas, through a Delphi exercise with international experts. The improved ability to differentiate these conditions radiographically will not only allow the clinicians to accurately approach patients but also will help the researchers to better classify patient phenotypes and focus on accurate radiographic outcomes.

Influence of physicochemical characteristics of calcium phosphate-based biomaterials in cranio-maxillofacial bone regeneration. A systematic literature review and meta-analysis of preclinical models.

Objectives: Calcium phosphate-based biomaterials (CaP) are the most widely used biomaterials to enhance bone regeneration in the treatment of alveolar bone deficiencies, cranio-maxillofacial and periodontal infrabony defects, with positive preclinical and clinical results reported. This systematic review aimed to assess the influence of the physicochemical properties of CaP biomaterials on the performance of bone regeneration in preclinical animal models. Methods: The PubMed, EMBASE and Web of Science databases were searched to retrieve the preclinical studies investigating physicochemical characteristics of CaP biomaterials. The studies were screened for inclusion based on intervention (physicochemical characterization and in vivo evaluation) and reported measurable outcomes. Results: A total of 1532 articles were retrieved and 58 studies were ultimately included in the systematic review. A wide range of physicochemical characteristics of CaP biomaterials was found to be assessed in the included studies. Despite a high degree of heterogeneity, the meta-analysis was performed on 39 studies and evidenced significant effects of biomaterial characteristics on their bone regeneration outcomes. The study specifically showed that macropore size, Ca/P ratio, and compressive strength exerted significant influence on the formation of newly regenerated bone. Moreover, factors such as particle size, Ca/P ratio, and surface area were found to impact bone-to-material contact during the regeneration process. In terms of biodegradability, the amount of residual graft was determined by macropore size, particle size, and compressive strength. Conclusion: The systematic review showed that the physicochemical characteristics of CaP biomaterials are highly determining for scaffold's performance, emphasizing its usefulness in designing the next generation of bone scaffolds to target higher rates of regeneration.

In Vivo feature of the regenerative potential of chitosan and alginate based osteoplastic composites doped with calcium phosphates, zinc ions, and vitamin D2.

PURPOSE: In vivo comparison of the regenerative potential of two calcium phosphate-biopolymer osteoplastic composites: а) based on alginate (Alg) and hydroxyapatite (HA) - Alg/HA/CS/Zn/D2, b) based on chitosan (CS) and brushite (DCPD) - CS/DCPD/D2. MATERIALS AND METHODS: 36 white male laboratory rats aged six months were used. A defect to the bone marrow canal in the middle of the femur diaphysis was made with a dental bur of 2 mm. The bone defect healed under the blood clot (control) in the different animal groups and was filled with Alg/HA/CS/Zn/D2 and CS/DCPD/D2. The regeneration of the bone defect was studied on the 30th, 90th, and 140th days by computer tomography (CT). RESULTS: On the 30th day, all groups' implantation site optical density (OD) was significantly lower than that of the adjacent maternal bone (MB). Intensity of bone formation for Alg/HA/CS/Zn/D2 exceeds CS/DCPD/D2. On the 90th day, the bone trauma site OD with Alg/HA/CS/Zn/D2 (1725.4 ± 86 HU) and CS/DCPD/D2 (1484.9 ± 69 HU) exceeded the OD of the control (942.5 ± 55 HU). On the 140th day, the OD of Alg/HA/CS/Zn/D2 and CS/DCPD/D2 implantation sites was higher than Control and MB OD. Visually, the area of the past injury with the Alg/HA/CS/Zn/D2 could be detected only by the presence of an endosteal bone callus and in the case of CS/DCPD/D2 - by the shadow of the remaining biomaterial in the bone marrow canal. CONCLUSIONS: According to CT data, Alg/HA/CS/Zn/D2 and CS/DCPD/D2 contribute to the complete healing of the femoral diaphysis defect in 140 days, but the regenerative potential of Alg/HA/CS/Zn/D2 from 30 days to 140 days is higher than CS/DCPD/D2 biomaterial.

Transition of endochondral bone formation at the normal and botulinum-treated mandibular condyle of growing juvenile rat.

OBJECTIVE: The aim of this study was to understand the temporal and spatial distribution of canonical endochondral ossification (CEO) and non-canonical endochondral ossification (NCEO) of the normal growing rat condyle, and to evaluate their histomorphological changes following the simultaneous hypotrophy of the unilateral masticatory closing muscles with botulinum toxin (BTX). DESIGN: 46 rats at postnatal 4 weeks were used for the experiment and euthanized at postnatal 4, 8, and 16 weeks. The right masticatory muscles of rats in experimental group were injected with BTX, the left being injected with saline as a control. The samples were evaluated using 3D morphometric, histological, and immunohistochemical analysis with three-dimensional regional mapping of endochondral ossifications. RESULTS: The results showed that condylar endochondral ossification changed from CEO to NCEO at the main articulating surface during the experimental period and that the BTX-treated condyle presented a retroclined smaller condyle with an anteriorly-shifted narrower articulating surface. This articulating region showed a thinner layer of the endochondral cells, and a compact distribution of flattened cells. These were related to the load concentration, decreased cellular proliferation with thin cellular layers, reduced extracellular matrix, increased cellular differentiation toward the osteoblastic bone formation, and accelerated transition of the ossification types from CEO to NCEO. CONCLUSION: The results suggest that endochondral ossification under loading tended to show more NCEO, and that masticatory muscular hypofunction by BTX had deleterious effects on endochondral bone formation and changed the condylar growth vector, resulting in a retroclined, smaller, asymmetrical, and deformed condyle with thin cartilage.

Histological evaluation of osseointegration between conventional and novel bone-level tapered implants in healed bone-A preclinical study.

AIMS: To histologically compare osseointegration and crestal bone healing between newly introduced tapered, self-cutting bone-level test implants and tapered bone-level control implants in sites with fully healed sites. METHODS: Sixty-six implants (33 test, 33 control) were placed 1 mm subcrestally in a minipig model and underwent qualitative histologic and quantitative histometric analyses after 3, 6 and 12 weeks of submerged healing. The primary and secondary outcomes were the bone-to-implant contact (BIC) and first bone-to-implant contact (fBIC). Outcomes between the test and control implants were statistically compared. RESULTS: The BIC values of the test implants were comparable and non-inferior over the time points studied, except for the 12 weeks time point which showed statistically significantly higher BIC values of the test (88.07 ± 5.35%) compared to the control implants (80.88 ± 7.51%) (p = .010). Similarly comparable and non-inferior were the fBIC values, except for the 6-week outcome, which showed statistically higher values for the test (-546.5 ± 450.80 µm) compared to the control implants (-75.7 ± 100.59 µm). fBIC results for the test implants were qualitatively more stable and consistent between test time points. CONCLUSION: Novel self-cutting bone-level test implants demonstrated superior osseointegration and similar bone levels compared to conventional bone-level implants after a healing period of 12 weeks in healed ridges.

A Biodegradable Nano-Drug Delivery Platform for Co-Delivery of Minocycline and Chitosan to Achieve Efficient and Safe Non-Surgical Periodontitis Therapy.

INTRODUCTION: Mesoporous silica nanoparticles (MSN) are widely used as ideal nanovehicles for the delivery of chemotherapeutic drugs. However, the balance between high anti-periodontitis activity and low biotoxicity has been challenging to maintain in most relevant studies owing to the slow degradation of silica in living organisms. METHOD: In this study, -responsive hydroxyapatite (HAP) was doped into the MSN skeleton, and the chemotherapeutic drug minocycline hydrochloride (MH) was loaded into the pores of MSN, forming a negatively charged drug delivery system. Cationic chitosan (COS) is a biodegradable material with high antibacterial performance and good biosafety. In this study, COS was immobilized on the surface of the drug-loaded particles through stable charge interaction to construct a composite drug delivery system (MH@MSNion@COS). RESULTS: In vitro and cellular experiments demonstrated effective degradation of the nanocarrier system and synchronized controlled release of the drug. Notably, compared with single MH administration, this system, in which MH and COS jointly regulated the expression levels of periodontitis- associated inflammatory factors (TNF-α, IL-6, IL-1ß, and iNOS), better inhibited the progress of periodontitis and induced tissue regeneration without showing significant toxic side effects in cells. CONCLUSION: This system provides a promising strategy for the design of intelligent, efficient, and safe anti-periodontitis drug delivery systems.

Symptomatic Heterotopic Bone Formation after 1,2 ICSRA in Scaphoid Nonunions.

Background We observed several cases of heterotopic bone formation after a 1,2 intercompartmental supraretinacular artery (1,2 ICSRA) distal radius vascularized bone graft (VBG) for the treatment of scaphoid nonunion. This adverse event seems underreported. Knowledge about factors associated with the formation of heterotopic bone after VBGs might help reduce this adverse event. Purpose What factors are associated with resected heterotopic bone formation after 1,2 ICSRA distal radius graft for the treatment of scaphoid nonunion? Patients and Methods We retrospectively reviewed all patients with a scaphoid nonunion treated with a 1,2 ICSRA distal radius graft between 2008 and 2019 in an urban level 1 trauma center in the Netherlands. We included 42 scaphoid nonunions in 41 people treated with the 1,2 ICSRA graft. We assessed potential correlation with patient, fracture, and treatment demographics. Results Heterotopic bone developed in 23 VBGs (55% [23/42]), of which 5 (12% [5/42]) were resected. Heterotopic bone was located radially (at the pedicle side) in all participants. Except a longer follow-up time ( p = 0.028), we found no variables associated with the development of heterotopic bone formation. Conclusion The location of the heterotopic bone at the pedicle site in all cases suggests a potential association with the periosteal strip. Surgeons might consider not to oversize the periosteal strip as a potential method to prevent heterotopic ossification after VBG. Level of Evidence Level II, prognostic study.

SIRT1 maintains bone homeostasis by regulating osteoblast glycolysis through GOT1.

The silent information regulator T1 (SIRT1) is linked to longevity and is a crucial mediator of osteoblast function. We investigated the direct role of Sirt1 during bone modeling and remodeling stages in vivo using Tamoxifen-inducible osteoblast-specific Sirt1 conditional knockout (cKO) mice. cKO mice exhibited lower trabecular and cortical bone mass in the distal femur. These phenotypes were coupled with lower bone formation and bone resorption. Metabolomics analysis revealed that the metabolites involved in glycolysis were significantly decreased in cKO mice. Further analysis of the quantitative acetylome revealed 11 proteins with upregulated acetylation levels in both the femur and calvaria of cKO mice. Cross-analysis identified four proteins with the same upregulated lysine acetylation site in both the femur and calvaria of cKO mice. A combined analysis of the metabolome and acetylome, as well as immunoprecipitation, gene knockout, and site-mutation experiments, revealed that Sirt1 deletion inhibited glycolysis by directly binding to and increasing the acetylation level of Glutamine oxaloacetic transaminase 1 (GOT1). In conclusion, our study suggested that Sirt1 played a crucial role in regulating osteoblast metabolism to maintain bone homeostasis through its deacetylase activity on GOT1. These findings provided a novel insight into the potential targeting of osteoblast metabolism for the treatment of bone-related diseases.

Primary stability and osseointegration comparing a novel tapered design tissue-level implant with a parallel design tissue-level implant. An experimental in vivo study.

OBJECTIVES: The aim of the present study was to compare a novel tapered, double-threaded self-tapping tissue-Level design implant (TLC) to a well-established parallel walled tissue-level (TL) implant in terms of primary and secondary stability over time. MATERIALS AND METHODS: Test TLC (n = 10/per timepoint) and control TL (n = 10/per timepoint) implants were placed in the mandible of minipigs and left for submerged healing for 3, 6, and 12 weeks. Maximum insertion torque and implant stability quotient (ISQ) were measured for each implant at placement. Osseointegration and cortical bone maintenance were histologically evaluated by measuring total bone-to-implant contact (BIC) and first bone-to-implant contact (fBIC). RESULTS: A significantly higher maximum insertion torque was measured for the test implant TLC compared to the control TL implant (57.83 ± 24.73 Ncm and 22.62 ± 23.16 Ncm, respectively; p < .001). The mean ISQ values were comparable between the two implant types (75.00 ± 6.70 for TL compared to 75.40 ± 3.20 for TLC, p = .988). BIC was comparable between both implant types at each of the evaluated time points. The fBIC was found to be significantly more coronal at 12 weeks for the TLC implant compared to the TL implant (0.31 ± 0.83 mm for TLC compared to -0.22 ± 0.85 for TL, p = .027). CONCLUSION: The novel tapered tissue level design implant showed improved primary stability and an overall improved crestal bone height maintenance compared to the parallel walled design at 12 weeks.

Material Design of Porous Hydroxyapatite Ceramics via Inverse Analysis of an Estimation Model for Bone-Forming Ability Based on Machine Learning and Experimental Validation of Biological Hard Tissue Responses.

Hydroxyapatite and ß-tricalcium phosphate have been clinically applied as artificial bone materials due to their high biocompatibility. The development of artificial bones requires the verification of safety and efficacy through animal experiments; however, from the viewpoint of animal welfare, it is necessary to reduce the number of animal experiments. In this study, we utilized machine learning to construct a model that estimates the bone-forming ability of bioceramics from material fabrication conditions, material properties, and in vivo experimental conditions. We succeeded in constructing two models: 'Model 1', which predicts material properties from their fabrication conditions, and 'Model 2', which predicts the bone-formation rate from material properties and in vivo experimental conditions. The inclusion of full width at half maximum (FWHM) in the feature of Model 2 showed an improvement in accuracy. Furthermore, the results of the feature importance showed that the FWHMs were the most important. By an inverse analysis of the two models, we proposed candidates for material fabrication conditions to achieve target values of the bone-formation rate. Under the proposed conditions, the material properties of the fabricated material were consistent with the estimated material properties. Furthermore, a comparison between bone-formation rates after 12 weeks of implantation in the porcine tibia and the estimated bone-formation rate. This result showed that the actual bone-formation rates existed within the error range of the estimated bone-formation rates, indicating that machine learning consistently predicts the results of animal experiments using material fabrication conditions. We believe that these findings will lead to the establishment of alternative animal experiments to replace animal experiments in the development of artificial bones.

Exercise promotes osteogenic differentiation by activating the long non-coding RNA H19/microRNA-149 axis.

BACKGROUND: Regular physical activity during childhood and adolescence is beneficial to bone development, as evidenced by the ability to increase bone density and peak bone mass by promoting bone formation. AIM: To investigate the effects of exercise on bone formation in growing mice and to investigate the underlying mechanisms. METHODS: 20 growing mice were randomly divided into two groups: Con group (control group, n = 10) and Ex group (treadmill exercise group, n = 10). Hematoxylin-eosin staining, immunohistochemistry, and micro-CT scanning were used to assess the bone formation-related indexes of the mouse femur. Bioinformatics analysis was used to find potential miRNAs targets of long non-coding RNA H19 (lncRNA H19). RT-qPCR and Western Blot were used to confirm potential miRNA target genes of lncRNA H19 and the role of lncRNA H19 in promoting osteogenic differentiation. RESULTS: Compared with the Con group, the expression of bone morphogenetic protein 2 was also significantly increased. The micro-CT results showed that 8 wk moderate-intensity treadmill exercise significantly increased bone mineral density, bone volume fraction, and the number of trabeculae, and decreased trabecular segregation in the femur of mice. Inhibition of lncRNA H19 significantly upregulated the expression of miR-149 and suppressed the expression of markers of osteogenic differentiation. In addition, knockdown of lncRNA H19 significantly downregulated the expression of autophagy markers, which is consistent with the results of autophagy-related protein changes detected in mouse femurs by immunofluorescence. CONCLUSION: Appropriate treadmill exercise can effectively stimulate bone formation and promote the increase of bone density and bone volume in growing mice, thus enhancing the peak bone mass of mice. The lncRNA H19/miR-149 axis plays an important regulatory role in osteogenic differentiation.

A moderate spinal contusion injury in rats alters bone turnover both below and above the level of injury with sex-based differences apparent in long-term recovery.

Spinal cord injury (SCI) leads to significant sublesional bone loss and high fracture rates. While loss of mechanical loading plays a significant role in SCI-induced bone loss, animal studies have demonstrated mechanical loading alone does not fully account for loss of bone following SCI. Indeed, we have shown that bone loss occurs below the level of an incomplete moderate contusion SCI, despite the resumption of weight-bearing and stepping. As systemic factors could also impact bone after SCI, bone alterations may also be present in bone sites above the level of injury. To examine this, we assessed bone microarchitecture and bone turnover in the supralesional humerus in male and female rats at two different ages following a moderate contusion injury in both sub-chronic (30 days) and chronic (180 days) time points after injury. At the 30-day timepoint, we found that both young and adult male SCI rats had decrements in trabecular bone volume at the supralesional proximal humerus (PH), while female SCI rats were not different from age-matched shams. At the 180-day timepoint, there were no statistical differences between SCI and sham groups, irrespective of age or sex, at the supralesional proximal humerus. At the 30-day timepoint, all SCI rats had lower BFR and higher osteoclast-covered trabecular surfaces in the proximal humerus compared to age-matched sham groups generally matching the pattern of SCI-induced changes in bone turnover seen in the sublesional proximal tibia. However, at the 180-day timepoint, only male SCI rats had lower BFR at the supralesional proximal humerus while female SCI rats had higher or no different BFR than their age-matched counterparts. Overall, this preclinical study demonstrates that a moderate contusion SCI leads to alterations in bone turnover above the level of injury within 30-days of injury; however male SCI rats maintained lower BFR in the supralesional humerus into long-term recovery. These data further highlight that bone loss after SCI is not driven solely by disuse. Additionally, these data allude to potential systemic factors exerting influence on bone following SCI and highlight the need to consider treatments for SCI-induced bone loss that impact both sublesional and systemic factors.

Intermittent administration of PTH for the treatment of inflammatory bone loss does not enhance entheseal pathological new bone formation.

OBJECTIVE: To investigate the effect of intermittent parathyroid hormone (iPTH) administration on pathological new bone formation during treatment of ankylosing spondylitis-related osteoporosis. METHODS: Animal models with pathological bone formation caused by hypothetical AS pathogenesis received treatment with iPTH. We determined the effects of iPTH on bone loss and the formation of pathological new bone with micro-computed tomography (micro-CT) and histological examination. In addition, the tamoxifen-inducible conditional knockout mice (CAGGCre-ERTM; PTHflox/flox, PTH-/-) was established to delete PTH and investigate the effect of endogenous PTH on pathological new bone formation. RESULTS: iPTH treatment significantly improved trabecular bone mass in the modified collagen-induced arthritis (m-CIA) model and unbalanced mechanical loading models. Meanwhile, iPTH treatment did not enhance pathological new bone formation in all types of animal models. Endogenous PTH deficiency had no effects on pathological new bone formation in unbalanced mechanical loading models. CONCLUSION: Experimental animal models of AS treated with iPTH show improvement in trabecular bone density, but not entheseal pathological bone formation，indicating it may be a potential treatment for inflammatory bone loss does in AS.

The design of an RGD in situ sustained delivery system utilizing scallop byssal protein through genetic engineering.

Although bioactive peptides enhancing bone healing have demonstrated effectiveness in treating bone defects, in vivo instability poses a challenge to their clinical application. Currently reported peptide delivery systems do not meet the demands of bone tissue repair regarding stability and peptide release efficacy. Herein, the self-assembling recombinant chimeric protein (Sbp5-2RGD) is developed by genetic engineering with cell adhesion peptide RGD as the targeted peptide and a newly discovered scallop byssal-derived protein Sbp5-2 that can assemble into wet stable films as the structural domain. In vitro studies show that the Sbp5-2RGD film exhibits excellent extensibility and biocompatibility. In vitro and in vivo degradation experiments demonstrate that the film remains stable due to the layer-by-layer degradation mode, resulting in sustained delivery of RGD in situ for up to 4 weeks. Consequently, the film can effectively promote osteogenesis, which accelerates bone defect healing and the implants osseointegration. Cell-level studies further show that the film up-regulates the expression of genes and proteins (ALP, OCN, OSX, OPN, RUNX2, VEGF) associated with osteogenesis and angiogenesis. Overall, this novel protein film represents an intelligent platform for peptide immobilization, protection, and release through its self-assembly, dense structure, and degradation mode, providing a therapeutic strategy for bone repair.