Bone Formation Research Articles

Activity of Selected Bone Formation and Angiogenesis Markers During the Treatment of Limb Length Discrepancy in Children Using Distraction Osteogenesis with the Circular Hexapod External Fixator

Background/Objectives: Limb lengthening and deformity correction techniques, particularly distraction osteogenesis, have significantly evolved in pediatric orthopedics. This study examines the temporal changes of key biochemical markers—vascular endothelial growth factor (VEGF), fibroblast growth factor 1 (FGF-1), and the propeptide of type I collagen (P1NP)—during the limb lengthening process. Methods: Twenty pediatric patients (aged 13–16) underwent distraction osteogenesis using the Circular Hexapod External Fixator. Peripheral blood samples were collected pre-treatment, three weeks after initiating distraction, and one month post-lengthening. Marker levels were measured using ELISA. Results: Serum VEGF concentrations significantly increased during treatment, peaking at T2 (T1 35.91 ± SD 5.54 vs. T2 293.47 ± SD 69.57, p < 0.0001), then declined at T3 (293.47 ± SD 69.57 vs. 40.86 ± SD 6.26, p < 0.0001). FGF-1 showed minor fluctuations initially but significantly increased by T3 (18.14 ± SD 4.57 vs. 41.56 ± SD 17.15, p < 0.01), about 2.3 times higher than baseline. P1NP concentrations exhibited a linear increase, with a significant rise from T2 to T3 (234.06 ± SD 36.57 vs. 280.68 ± SD 35.63, p < 0.05), while the T1 to T2 increase was not statistically significant, indicating ongoing osteoblastic activity and bone formation. Conclusions: This study highlights the dynamic changes in VEGF, FGF-1, and P1NP during distraction osteogenesis, emphasizing their roles as biomarkers of bone regeneration. These findings enhance the understanding of bone healing mechanisms and could inform future therapeutic strategies for pediatric limb lengthening. Further research is warranted to explore their clinical utility.

The Effect of Local Melatonin Application on Bone Fracture Healing in Rat Tibias

Background and Objectives: This study aimed to histologically evaluate the effects of local melatonin application at different doses on bone fracture healing. Materials and Methods: Thirty rats were divided into three groups, with ten rats in each group. In the control group (n = 10), a fracture line was created in the tibial bones, and fracture osteosynthesis was performed without any additional procedure. In the local melatonin dose 1 (MLT D-1) group (n = 10), a fracture line was created in the tibial bones, and 1.2 mg of lyophilized powder melatonin was applied locally before fracture osteosynthesis. In the local melatonin dose 2 (MLT D-2) group (n = 10), a fracture line was created in the tibial bones, and 3 mg of lyophilized powder melatonin was applied locally before fracture osteosynthesis. After a 12-week healing period, all subjects were sacrificed, and tibial bones were collected for histomorphometric analysis. Results: The percentage of bone formation was significantly higher in the MLT D-1 and MLT D-2 groups than in the control group. There was no statistically significant difference between the MLT D-1 and MLT D-2 groups. Conclusions: In conclusion, the study demonstrated that local melatonin application supports bone fracture by increasing bone formation, although different doses of melatonin did not lead to significant variations in fracture healing.

A CD26+ tendon stem progenitor cell population contributes to tendon repair and heterotopic ossification

Abstract Inadequate tendon healing and heterotopic bone formation result in substantial pain and disability, yet the specific cells responsible for tendon healing remain uncertain. Here we identify a CD26+ tendon stem/progenitor cells residing in peritendon, which constitutes a primitive stem cell population with self-renewal and multipotent differentiation potentials. CD26+ tendon stem/progenitor cells migrate into the tendon midsubstance and differentiation into tenocytes during tendon healing, while ablation of these cells led to insufficient tendon healing. Additionally, CD26+ tendon stem/progenitor cells contribute to heterotopic ossification and Tenascin-C-Hippo signaling is involved in this process. Targeting Tenascin-C significantly suppresses chondrogenesis of CD26+ tendon stem/progenitor cells and subsequent heterotopic ossification. Our findings provide insights into the identification of tendon stem/progenitor cells and illustrate the essential role of CD26+ tendon stem/progenitor cells in tendon healing and heterotopic bone formation.

Time-lapse HR-pQCT reliably assesses and monitors local bone turnover in patients with chronic kidney disease.

Bone turnover assessment and monitoring are essential for chronic kidney disease (CKD)-associated bone care. Patients with CKD suffer from significantly elevated fracture risk due to abnormally high or low bone turnover, which requires diametrically opposite treatments informed by patient-specific bone turnover data. However, a reliable, accessible, non-invasive bone turnover assessment and monitoring tool remains an unmet clinical need. Combining time-lapse (TL) analysis with high-resolution peripheral quantitative computed tomography (HR-pQCT) scans obtained over time allows for in vivo temporospatial bone remodeling assessment. This study aimed to evaluate the feasibility of applying TL HR-pQCT to assess and monitor local bone formation and resorption in patients with CKD. A customized TL HR-pQCT pipeline was developed on a second-generation HR-pQCT platform and optimized using ex vivo cadaveric phantom and in vivo scan-rescan HR-pQCT images. The annualized least significant change in bone formation and resorption were evaluated using in vivo longitudinal reproducibility images. Finally, the feasibility of the TL HR-pQCT pipeline in assessing and monitoring bone turnover was evaluated in patients with end stage kidney disease (ESKD; n = 9). We found that a 2-month time-lapse period was sufficient for the TL HR-pQCT pipeline to reliably assess and monitor local bone turnover in a cohort of patients with ESKD. We also demonstrated the importance of characterizing TL HR-pQCT precision metrics using longitudinal baseline/follow-up rather than short-term scan-rescan datasets. The TL HR-pQCT pipeline assessed a range of bone formation metrics consistent with the gold standard histomorphometric bone formation reported in the literature for patients with CKD and ESKD. Our findings highlight that TL HR-pQCT holds promise as a "virtual bone biopsy" that reliably assesses and monitors local bone turnover for CKD bone care. Subsequent work will focus on validating this TL HR-pQCT pipeline against the gold standard bone biopsy with quantitative histomorphometry.

From Waste to Innovation: A Circular Economy Approach for Tissue Engineering by Transforming Human Bone Waste into Novel Collagen Membranes

The aim of the circular economy is to treat waste as a valuable raw material, reintegrating it into the industrial economy and extending the lifecycle of subsequent products. Efforts to reduce the production of hard-to-recycle waste are becoming increasingly important to manufacturers, not only of consumer goods but also of specialized items that are difficult to manufacture, such as medical supplies, which have now become a priority for the European Union. The purpose of the study is to manufacture a novel human-purified type I collagen membrane from bone remnants typically discarded during the processing of cortico-cancellous bones in tissue banks and to evaluate its mechanical properties and effectiveness in regenerating bone-critical mandibular defects in rabbits. To prepare the novel membrane, cortico-cancellous bone chip samples from a local tissue bank were processed to isolate collagen by demineralization under agitation in HCl, cast into a silicone mold, and air-dried at room temperature and UV irradiation. The average thickness of the four batches analyzed by SEM was 37.3 μm. The average value of Young’s modulus and tensile strength obtained from the specimens was 2.56 GPa and 65.43 Mpa, respectively. The membrane’s efficacy was tested by creating a critical bicortical and bilateral osteoperiosteal defect in rabbit mandibles. The right-side defects were covered with the collagen membrane, while the left-side defects were left untreated as a control. Nine weeks post-surgery, clinical, radiological, and histological analyses demonstrated new bone formation in the treated areas, whereas the control sites showed no bone regeneration. This innovative approach not only contributes to sustainability in healthcare by optimizing biological waste but also exemplifies efficient resource use in line with the circular economy, offering a cost-effective, biocompatible option that could benefit national health systems.

FOXG1 promotes osteogenesis of bone marrow-derived mesenchymal stem cells by activating autophagy through regulating USP14

The osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) is key for bone formation, and its imbalance leads to osteoporosis. Forkhead Box Protein G1 (FOXG1) is associated with osteogenesis, however, the effect of FOXG1 on osteogenesis of BMSCs and ovariectomy (OVX)-induced bone loss is unknown. In our study, FOXG1 expression in BMSCs increases after osteogenic induction. FOXG1 overexpression significantly increases osteoblast marker expression ALP activity, and calcium deposition, while the opposite results are observed in FOXG1 knockdown BMSCs, suggesting that FOXG1 promotes osteogenic differentiation. Additionally, autophagy promotes the differentiation process in BMSCs. We find that FOXG1 induces autophagy, and osteogenic differentiation is blocked via inhibiting FOXG1-caused autophagy, indicating that FOXG1 accelerates osteogenic differentiation via inducing autophagy. Eight-week-old female C57BL/6J mice are used in OVX models, FOXG1 overexpression decreases bone loss by increasing bone formation. Moreover, FOXG1 overexpression suppresses osteoclast differentiation. Mechanically, FOXG1 transcriptionally represses ubiquitin-specific protease14 (USP14) via binding to the USP14 promoter. USP14 overexpression prevents the promoting effect of FOXG1 on osteogenic differentiation in BMSCs. Therefore, our findings suggest that FOXG1 promotes BMSC osteogenic differentiation and inhibits osteoclast differentiation, eventually blocking OVX-induced bone loss, which may provide a promising approach for osteoporosis treatment.

Low-intensity pulsed ultrasound enhances the osteogenic potential of PDLSCs-derived extracellular vesicles through COMP/PI3K/AKT.

The therapeutic potential of extracellular vesicles (EVs) in bone regeneration is noteworthy; however, their clinical application is impeded by low yield and limited efficacy. This study investigated the effect of low-intensity pulsed ultrasound (LIPUS) on the therapeutic efficacy of EVs derived from periodontal ligament stem cells (PDLSCs) and preliminarily explored its mechanism. PDLSCs were cultured with osteogenic media and stimulated with or without LIPUS, and then EVs and LIPUS-stimulated EVs (L-EVs) were isolated separately. We investigated the biological characteristics and effects of these two EVs on cell proliferation, migration, osteogenic differentiation, and bone regeneration invivo and invitro, and explored the potential mechanism by analyzing protein profiles. LIPUS significantly stimulated the secretion of PDLSCs-EVs, and L-EVs exhibited stronger efficacy in promoting cell proliferation, migration, and osteogenic differentiation, thereby enhancing new bone formation. LIPUS stimulation affected the protein profile of PDLSCs-EVs, and 42 proteins were upregulated and 4 proteins downregulated in L-EVs when compared with EVs. LIPUS significantly upregulated the level of cartilage oligomeric matrix protein (COMP) in EVs, which enhanced EVs' osteogenic ability via the PI3K/AKT pathway. This study proposes that LIPUS has potential as an optimization method for enhancing the therapeutic effects of EVs in tissue regeneration.

Effect of romosozumab on bone mineral density and trabecular bone score in premenopausal women with low bone mass.

Romosozumab, an anti-sclerostin antibody, is a promising anabolic agent that increases bone formation and decreases bone resorption. However, its efficacy in premenopausal women with low bone mass remains understudied. We retrospectively reviewed premenopausal women with low bone mass treated with romosozumab (ROMO group) or drug-naïve patients (control group). Patients in the ROMO group were classified into the glucocorticoid-induced osteoporosis (GIOP), idiopathic osteoporosis (IOP), and pregnancy and lactation-induced osteoporosis (PLO) subgroups. Bone mineral density (BMD) and trabecular bone score (TBS) were measured before and after one year of romosozumab treatment. Twenty-five patients in the ROMO group and five in the control group were included in the study. Among patients in the ROMO group, 12 were in the GIOP, 9 in the IOP, and 4 in the PLO subgroups. The mean age was 37.0years [32.0-42.0], and the median body mass index was 18.8kg/m2 [17.5-21.3]. After romosozumab treatment, lumbar spine (LS), femur neck (FN) BMD, and TBS increased from baseline (LSBMD, 12.8% [8.2-19.3], p < 0.001; FNBMD, 4.6% [- 0.6-10.7], p = 0.016; TBS, 4.1% ± 3.8, p < 0.001) in the ROMO group. Patients in both the GIOP and IOP subgroups showed a significant increase in LSBMD, while those in the IOP subgroup demonstrated significant increases in FNBMD. We demonstrated romosozumab's efficacy in BMD increment in premenopausal women. Romosozumab may be a potential treatment option for premenopausal women with low bone mass, regardless of etiologies, although further research on fracture risk reduction is warranted.

Synergistic Effect of Strontium Doping and Surfactant Addition in Mesoporous Bioactive Glass for Enhanced Osteogenic Bioactivity and Advanced Bone Regeneration

Mesoporous bioactive glass (MBG) is an advanced biomaterial widely recognized for its application in bone regenerative engineering. This study synthesized an MBG powder (80 mol% SiO2, 5 mol% P2O5, and 15 mol% CaO) using a facile sol-gel method with the non-ionic surfactant Pluronic® P123, which acted as a pore-forming agent. MBGs form bioactive surfaces that facilitate HA formation, and the presence of Pluronic® P123 increases the surface area and promotes HA nucleation. Various percentages of strontium (Sr) doping were examined to improve bioreactivity, biological response, and bone formation, with 3SMBG (3 mol% Sr) showing the highest specific surface area. In vitro biocompatibility tests revealed HA formation on all glass surfaces after immersion in simulated body fluid (SBF), indicated by sheet-like HA morphologies, the presence of PO43− and CO32− functional groups, and the amorphous structure along with SrCO3 crystalline phases corresponding to HA and Sr-HA structures. Sr doping resulted in delayed initial degradation and sustained release of Sr2+, achieving over 95% cell viability. Surfactant-induced mesoporous structure and Sr incorporation synergistically enhance osteocyte induction and formation in vitro. These findings suggest that Sr-doped MBG, particularly with P123-assisted Sr/Ca substitution, optimizes the material’s properties for advanced bone regenerative applications.

Photothermal Coating on Zinc Alloy for Controlled Biodegradation and Improved Osseointegration.

Zinc (Zn) and its alloys are promising biomaterials for orthopedic applications due to their degradability and mechanical properties. Zn2+plays a crucial role in bone formation, but excessive early release may cause cytotoxicity and inhibit osseointegration. To solve this, we developed a near-infrared (NIR) light-controlled polycaprolactone/copper-sulfur (PCL/CuS) coating that slows degradation and enhances osseointegration of Zn alloys. The zinc-lithium (Zn-Li) substrate is encapsulated with PCL, reducing Zn2+ release and maintaing biocompatibility. Controlled Zn2+ release and mild photothermal therapy via CuS nanoparticles promoted osteogenesis. In vitro studies demonstrated enhanced cell proliferation and osteogenic differentiation. In vivo Micro-Computed Tomography (Micro-CT), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), and immunohistochemical analyses confirmed improved osseointegration. Mechanistic studies using RNA sequencing and Western blotting revealed that the coating promotes osteogenesis by activating the Wnt/β-catenin and inhibiting NF-κB pathways. This NIR light-controlled PCL/CuS coating successfully regulates Zn alloy degradation, enhances osseointegration via controlled Zn2+ release and mild photothermal therapy effct, presenting a promising avenue for orthopedic biomaterials.

Crystal Structures of Antigen-Binding Fragment of Anti-Osteocalcin Antibody KTM219

Osteocalcin is a useful biomarker for bone formation and bone-related diseases. KTM219 is an anti-osteocalcin C-terminal peptide antibody. The single-chain variable region (scFv) and antigen-binding fragment (Fab) of KTM219 are applicable to the Quenchbody (Q-body) immunoassay. Q-body is a new type of fluorescent immunosensor, which is scFv or Fab labeled with a fluorescent dye. When Q-body binds to its antigen, the fluorescence intensity increases. The highly sensitive detection of antigens by changes in fluorescence intensity is performed in a single step by mixing the sample and reagent. In this study, to reveal the recognition mechanism of the KTM219 antibody and to discuss the structural basis for Q-body, we solved the crystal structures of Fab of the anti-osteocalcin antibody KTM219 and its complex with the antigen osteocalcin C-terminal peptide (BGP-C7). Also, we solved the structure of a KTM219 Fab crystal grown in the presence of a fluorescent dye, carboxytetramethylrhodamine (TAMRA); however, tightly bound TAMRA was not found in the electron density map. We predicted the binding sites of TAMRA in the antigen-binding pocket by docking simulations. These results support the proposed Q-body mechanism. The crystal structures of KTM219 Fab would be useful for further development and improvement of Q-body fluorescent immunosensors.

Biomimetic Extracellular Vesicles Containing Biominerals for Targeted Osteoporosis Therapy.

Osteoporosis (OP) is a systemic skeletal disorder characterized by decreased bone mineral density and a heightened risk of fractures. Therapies for OP have primarily focused on balancing bone formation and bone resorption, but enhancing the remineralization of osteoporotic bone is also a key strategy for effective repair. Recent insights into biomineralization mechanisms have highlighted the essential role of mineral-containing extracellular vesicles (EVs) secreted by osteoblasts in promoting bone marrow mesenchymal stromal/stem cell (BMSC) differentiation and initiating matrix mineralization. Drawing from these principles, we developed a biomimetic approach to replicate the structure and function of the osteoblast-derived EVs by engineering biomimetic mitochondrial minerals with bone marrow homing cell membranes (CMs). This bone-targeted biomimetic system exhibits excellent biocompatibility, enhancing osteogenic differentiation and stimulating angiogenesis by regulating cellular energy metabolism. Additionally, the CM-coated structure shows affinity for collagen fibrils, effectively enhancing intrafibrillar collagen mineralization, thereby facilitating osteoporotic bone repair. Overall, the biomimetic system offers a safe and efficient therapeutic alternative, positioning it as a platform for bone tissue engineering and regenerative medicine.

Influencing fracture healing by specific osteoporosis medications

Osteoporosis is a widespread disease defined by areduction in bone mass and structure, thereby increasing the risk of fragility fractures. Treatment typically involves specific medications, which either inhibit bone resorption (antiresorptive) or stimulate bone formation (anabolic) and may potentially influence the healing of osteoporotic fractures. On the other hand, metabolic disorders, immune system dysfunctions or circulatory problems can impair fracture healing. Therefore, the targeted use of osteoporosis medications could be astrategy to promote the healing of impaired fractures. The aim of this study is to provide acurrent overview of the effects of osteoporosis medications approved in Germany on fracture healing. The focus is on the potential influence of these medications in the context of osteoporosis treatment. Additionally, the current state of research is examined to explore to what extent the targeted use of these medications could improve fracture healing. Aliterature search was conducted in the PubMed database using topic-specific keywords. Preclinical studies, clinical trials, review articles and meta-analyses were considered to present the current scientific knowledge with clinical relevance. Preclinical and clinical studies suggest that specific osteoporosis medications do not have aclinically relevant negative impact on the healing of fragility fractures. Osteoanabolic substances even tend to have apositive effect on fracture healing in both normal and impaired healing processes; however, the available studies are limited and none of the medications have been approved for this specific use. Osteoporosis medications with antiresorptive or osteoanabolic effects are primarily used to treat osteoporosis, especially after fragility fractures, to reduce the risk of further fractures. There is no clinically relevant impairment of fracture healing due to these medications. Further studies would be required to obtain approval for these medications specifically to improve fracture healing.

DAMPs, PAMPs, NLRs, RIGs, CLRs and TLRs - Understanding the Alphabet Soup in the Context of Bone Biology.

The purpose of this review is to summarize the current understanding of cell-autonomous innate immune pathways that contribute to bone homeostasis and disease. Germ-line encoded pattern recognition receptors (PRRs) are the first line of defense against danger and infections. In the bone microenvironment, PRRs and downstream signaling pathways, that mount immune defense, interface intimately with the core cellular processes in bone cells to alter bone formation and resorption. The role of PRR engagement on bone remodeling has been best described as a result of activated macrophages secreting effector molecules that reshape the characteristics of bone-resident cells. However, it is being increasingly recognized that local bone resident-cells like osteoclasts and osteoblasts possess an arsenal of PRRs. The engagement of these PRRs by stimuli in the bone niche can drive cell-autonomous (aka cell-intrinsic) responses that, in turn, impact bone-remodeling dramatically, irrespective of immune cell effectors. Indeed, this vital role for cell-autonomous innate immune responses is evident in how reduced PRR activity within osteoclast progenitors correlates with their reduced differentiation and abnormal bone remodeling. Further, cell-intrinsic PRR activity has now been shown to influence the behavior of osteoblasts, osteocytes and other local immune/non-immune cell populations. However, distinct PRR families have varying impact on bone homeostasis and inflammation, emphasizing the importance of investigating these different nodes of innate immune signaling in bone cells to better identify how they synergistically and/or antagonistically regulate bone remodeling in the course of an immune response. Innate immune sensing within bone resident cells is a critical determinant for bone remodeling in health and disease.

Differential bone and vessel type formation at superior and dura periosteum during cranial bone defect repair

The cranial mesenchyme, originating from both neural crest and mesoderm, imparts remarkable regional specificity and complexity to postnatal calvarial tissue. While the distinct embryonic origins of the superior and dura periosteum of the cranial parietal bone have been described, the extent of their respective contributions to bone and vessel formation during adult bone defect repair remains superficially explored. Utilizing transgenic mouse models in conjunction with high-resolution multiphoton laser scanning microscopy (MPLSM), we have separately evaluated bone and vessel formation in the superior and dura periosteum before and after injury, as well as following intermittent treatment of recombinant peptide of human parathyroid hormone (rhPTH), Teriparatide. Our results show that new bone formation along the dura surface is three times greater than that along the superior periosteal surface following injury, regardless of Teriparatide treatment. Targeted deletion of PTH receptor PTH1R via SMA-CreER and Col 1a (2.3)-CreER results in selective reduction of bone formation, suggesting different progenitor cell pools in the adult superior and dura periosteum. Consistently, analyses of microvasculature show higher vessel density and better organized arterial-venous vessel network associated with a 10-fold more osteoblast clusters at dura periosteum as compared to superior periosteum. Intermittent rhPTH treatment further enhances the arterial vessel ratio at dura periosteum and type H vessel formation in cortical bone marrow space. Taken together, our study demonstrates a site-dependent coordinated osteogenic and angiogenic response, which is determined by regional osteogenic progenitor pool as well as the coupling blood vessel network at the site of cranial defect repair.

Biological Behavior of Bioactive Glasses SinGlass (45S5) and SinGlass High (F18) in the Repair of Critical Bone Defects

This study evaluated the osteogenic potential of the bioactive glasses SinGlass (45S5) and SinGlass High (F18) in regenerating critical bone defects in rat calvaria. Both biomaterials promoted new bone formation around the particles, with the SinGlass High (F18) group exhibiting a higher rate of bone maturation. Histomorphological and birefringence analyses revealed better organization of the newly formed bone in the biomaterial-treated groups, and immunohistochemistry indicated the expression of osteogenic markers such as osteocalcin, immunostaining for bone morphogenetic protein 2 (BMP 2), and immunostaining for bone morphogenetic protein 4 (BMP 4). Microtomography computadorized (Micro-CT) revealed centripetal bone formation in both groups, with greater integration of the particles into the surrounding bone tissue. The superior performance of SinGlass High (F18) was attributed to its higher potassium and magnesium content, which enhance osteoconductivity. After 42 days, the SinGlass High (F18) group showed the highest percentage of new bone formation, in line with previous studies. Although our results are promising, the limited follow-up period and use of a single animal model highlight the need for further research to validate clinical applicability. SinGlass High (F18) appears to be a viable alternative to autografts in bone repair, with potential to improve tissue integration and accelerate recovery.

Short-acting growth hormone supplementation for bone age and growth rate in children with idiopathic short stature: a meta-analysis

ObjectiveTo explore the effect of short-acting growth hormone (GH) supplementation on bone age and growth rate of children with idiopathic short stature.MethodsThe authoritative databases such as PubMed, Medline, and Web of Science were extensively searched through the systematic and comprehensive literature retrieval strategy to compile the clinical research data on the treatment of idiopathic short stature with short-acting GH. The study will be strictly screened to ensure that all enrolled research subjects are patients with idiopathic short stature, and the intervention method is defined as short-acting GH replacement therapy, and a reasonable control group is set, such as placebo treatment, to ensure the scientificity and comparability of research results. Outcome index data such as basic characteristics, sample size, follow-up time, and total effective rate of the included studies were extracted. In this study, RevMan 5.3, a professional statistical software tool, was used to systematically perform the meta-analysis process. Weighted average difference (WMD) was calculated as the primary outcome to evaluate the effect of bone age and growth rate, and the WAD in adverse reactions was considered as the secondary outcome.ResultsNine studies were included in the study, and 491 patients with idiopathic short stature were included in the study. The results of the meta-analysis showed that there was no significant difference in bone age but a significant difference in growth rate when compared with the control group.ConclusionShort-acting GH supplementation can significantly improve the growth rate of children with idiopathic short stature, but has little effect on bone age.

Short bouts and long-term exercise reduce sedentary-induced bone loss and microstructural changes by modulating bone formation and resorption in healthy young male rats

Although the toxic effect of Sedentary behavior (SED) on bone health has been demonstrated in the previous study, the underlying mechanisms of SED, or break SED to bone health remain unclear. In this study, we aim to investigate the effects of sedentary behavior (SED) on bone health, as well as the potential favor effects of moderate to vigorous physical activity (MVPA) and periodic interruptions of SED. To simulate SED, we used small Plexiglas cages (20.0 × 9.0 × 10.0 cm) to restrict animal movement. Short bursts of exercise to break SED and continuous long-term exercise were also designed. After an 8-weeks period of SED, we observed decreased bone mass and bone microstructure. Specifically, there was a notable decrease in the bone mineral density (BMD), bone surface (BS) and cortical thickness (Ct.Th) significantly reduced in cortical bone. In the trabecular bone, parameters such as trabecular separation (Tb.Sp), trabecular number (Tb.N), BS, connectivity density (Conn.D), BS/BV, bone volume/tissue volume (BV/TV), degree of anisotropy (DA), and structural model index (SMI) were also significantly reduced. In addition, we detected an increase in serum tartrate-resistant acid phosphatase (TRAP) levels in SED rats at both 4 and 8 weeks. At 8 weeks, the osteoclast number and surface with TRAP-staining were significantly increased, however, the OPG mRNA and proteins level were significantly decreased. After daily short bouts exercise and long-term exercise, we observed improvements in bone mass and microstructure. These improvements included increasing BMD and BV/TV of cortical bone, and improving Conn.D, BV/TV, DA and SMI of trabecular. Meanwhile, we found that, at 4 and 8 weeks, there was an increase in serum ALP. At 8 weeks, the mineralized nodules surface with Alizarin Red S-staining, and OPG mRNA and proteins level in bone tissue were significantly increased. Our findings suggest that SED leads to alterations in the bone mass and microstructure, which are associated with the changes in the OPG protein and bone remodeling. Exercise, whether in short daily bouts or continuous long-term sessions, can ameliorate the harmful effects of SED. Similarly, the changes in bone mass and microstructure from exercise are also associated with the changes in the OPG protein and bone remodeling by upregulated osteoblast activity to bone formation. Overall, our findings indicate the importance of physical activity in maintaining bone health and preventing the negative impacts of prolonged SED.

β-ecdysone/PLGA composite scaffolds promote skull defect healing in diabetic rat

IntroductionDiabetes mellitus often leads to bone metabolism disorders, hindering bone regeneration and delaying the healing of bone defects. β-Ecdysone, a plant-derived hormone known for its wide range of physiological activities, possesses hypoglycemic effects and promotes osteogenic differentiation. This study developed a composite PLGA slow-release scaffold loaded with β-ecdysone to enhance its bioavailability through topical administration and to investigate its potential to heal diabetic bone defects.MethodsThe composite scaffolds were fabricated using solution casting/particle leaching and freeze-drying techniques. Then a series of characterizations were subjected to test the performance of composite scaffolds, and in vitro safety of the composite scaffolds was tested by CCK8 assay and live/dead cell staining. Further, micro-CT and histology to evaluate the effect of β-E/PLGA composite scaffolds on healing of skull defects in diabetic rats at 4 and 8 weeks after implantation. Simultaneously, the safety of the scaffolds in vivo was also evaluated.ResultsThe material characterization results indicated that, in comparison to the single-pore size scaffold, the composite scaffold exhibited superior porosity, swelling ratio, drug loading capacity, and mechanical properties. Additionally, the composite scaffolds showed appropriate degradation performance and sustained drug release profiles. The CCK8 cytotoxicity assay and live/dead cell staining demonstrated that BMSCs survived and proliferated on the composite scaffold under both low-glucose and high-glucose conditions. Micro-CT and histological investigation demonstrated that β-E/PLGA composite scaffolds promoted new bone growth in the skull defect region of diabetic rats.ConclusionOverall, these findings suggest that the β-E/PLGA composite scaffolds promote the healing of bone defects in diabetic rats. The combination of β-ecdysone and tissue-engineered scaffolds presents a promising approach for treating diabetes-related bone defects.

Spatial histomorphometry reveals that local peripheral nerves modulate but are not required for skeletal adaptation to applied load in mice

Abstract Mechanical loading is required for bone health and results in skeletal adaptation to optimize strength. Local nerve axons, particularly within the periosteum, may respond to load-induced biomechanical and biochemical cues. However, their role in the bone anabolic response remains controversial. We hypothesized that spatial alignment of periosteal nerves with sites of load-induced bone formation would clarify this relationship. To achieve this, we developed RadialQuant, a custom tool for spatial histomorphometry. Tibiae of control and neurectomized (sciatic/femoral nerve cut) pan-neuronal Baf53b-tdTomato reporter mice were loaded for 5-days. Bone formation and periosteal nerve axon density were then quantified simultaneously in non-decalcified sections of the mid-diaphysis using RadialQuant. In control animals, anabolic loading induced maximal periosteal bone formation at the site of peak compression, as has been reported previously. By contrast, loading did not significantly change overall periosteal nerve density. Neurectomy depleted ~90% of all periosteal axons, with near-total depletion on load-responsive surfaces. Neurectomy alone also caused de novo bone formation on the lateral aspect of the mid-diaphysis. However, neurectomy did not inhibit load-induced increases in periosteal bone area, mineralizing surface, or bone formation rate. Rather, neurectomy spatially redistributed load-induced bone formation towards the lateral tibial surface with a reduction in periosteal bone formation at the posterolateral apex (-63%) and enhancement at the lateral surface (+1360%). Altogether, this contributed to comparable load-induced changes in cortical bone area fraction. Our results show that local skeletal innervation modulates but is not required for skeletal adaptation to applied load in our model. This supports the continued use of loading and weight-bearing exercise as an effective strategy to increase bone mass, even in patients with peripheral nerve damage or dysfunction.