Pathophysiological mechanism of acute bone loss after fracture

An adaptive biodegradable zinc alloy with bidirectional regulation of bone homeostasis for treating fractures and aged bone defects

Healing of fractures or bone defects is significantly hindered by overactivated osteoclasts and inhibited osteogenesis in patients with abnormal bone metabolism. Current clinical approaches using titanium alloys or stainless steel provide mechanical support but have no biological effects on bone regeneration. Therefore, designing and fabricating degradable metal materials with sufficient mechanical strength and bidirectional regulation of both osteoblasts and osteoclasts is a substantial challenge. Here, this study first reported an adaptive biodegradable Zn-0.8 Mg alloy with bidirectional regulation of bone homeostasis, which promotes osteogenic differentiation by activating the Pi3k/Akt pathway and inhibits osteoclast differentiation by inhibiting the GRB2/ERK pathway. The anti-osteolytic ability of the Zn-0.8 Mg alloy was verified in a mouse calvarial osteolysis model and its suitability for internal fracture fixation with high-strength screws was confirmed in the rabbit femoral condyle fracture model. Furthermore, in an aged postmenopausal rat femoral condyle defect model, 3D printed Zn-0.8 Mg scaffolds promoted excellent bone regeneration through adaptive structures with good mechanical properties and bidirectionally regulated bone metabolism, enabling personalized bone defect repair. These findings demonstrate the substantial potential of the Zn-0.8 Mg alloy for treating fractures or bone defects in patients with aberrant bone metabolism.

Navigating Post-Traumatic Osteoporosis: A Comprehensive Review of Epidemiology, Pathophysiology, Diagnosis, Treatment, and Future Directions

Post-traumatic osteoporosis (PTO) presents a significant challenge in clinical practice, characterized by demineralization and decreased skeletal integrity following severe traumatic injuries. This literature review manuscript addresses the knowledge gaps surrounding PTO, encompassing its epidemiology, pathophysiology, risk factors, diagnosis, treatment, prognosis, and future directions. This review emphasizes the complexity of the etiology of PTO, highlighting the dysregulation of biomineralization processes, inflammatory cytokine involvement, hormonal imbalances, glucocorticoid effects, vitamin D deficiency, and disuse osteoporosis. Moreover, it underscores the importance of multidisciplinary approaches for risk mitigation and advocates for improved diagnostic strategies to differentiate PTO from other musculoskeletal pathologies. This manuscript discusses various treatment modalities, including pharmacotherapy, dietary management, and physical rehabilitation, while also acknowledging the limited evidence on their long-term effectiveness and outcomes in PTO patients. Future directions in research are outlined, emphasizing the need for a deeper understanding of the molecular mechanisms underlying PTO and the evaluation of treatment strategies' efficacy. Overall, this review provides a comprehensive overview of PTO and highlights avenues for future investigation to enhance clinical management and patient outcomes.

Kyphoplasty is associated with reduced mortality risk for osteoporotic vertebral compression fractures: a systematic review and meta-analysis

BACKGROUND

Vertebral augmentation, such as vertebroplasty (VP) or kyphoplasty (KP), has been utilized for decades to treat OVCFs; however, the precise impact of this procedure on reducing mortality risk remains a topic of controversy. This study aimed to explore the potential protective effects of vertebral augmentation on mortality in patients with osteoporotic vertebral compression fractures (OVCFs) using a large-scale meta-analysis.

MATERIALS AND METHODS

Cochrane Library, Embase, MEDLINE, PubMed and Web of Science databases were employed for literature exploration until May 2023. The hazard ratios (HRs) and 95% confidence intervals (CIs) were utilized as a summary statistic via random-effect models. Statistical analysis was executed using Review Manager 5.3 software.

RESULTS

After rigorous screening, a total of five studies with substantial sample sizes were included in the quantitative meta-analysis. The total number of participants included in the study was an 2,421,178, comprising of 42,934 cases of vertebral augmentation and 1,991,244 instances of non-operative management. The surgical intervention was found to be significantly associated with an 18% reduction in the risk of mortality (HR 0.82; 95% CI 0.78, 0.85). Subgroup analysis revealed a remarkable 71% reduction in mortality risk following surgical intervention during short-term follow-up (HR 0.29; 95% CI 0.26, 0.32). Furthermore, KP exhibited a superior and more credible decrease in the risk of mortality when compared to VP treatment.

CONCLUSIONS

Based on a comprehensive analysis of large samples, vertebral augmentation has been shown to significantly reduce the mortality risk associated with OVCFs, particularly in the early stages following fractures. Furthermore, it has been demonstrated that KP is more reliable and effective than VP in terms of mitigating mortality risk.

A comparative study of image quality and diagnostic confidence in diagnosis and follow-up of scaphoid fractures using photon-counting detector CT and energy-integrating detector CT

PURPOSE

Scaphoid fractures in patients and assessment of healing using PCD-CT have, as far as we know, not yet been studied. Therefore, the aim was to compare photon counting detector CT (PCD-CT) with energy integrating detector CT (EID-CT) in terms of fracture visibility and evaluation of fracture healing.

METHOD

Eight patients with scaphoid fracture were examined with EID-CT and PCD-CT within the first week post-trauma, and with additional scans at 4, 6 and 8 weeks. Our clinical protocol for wrist examination with EID-CT was used (CTDIvol 3.1 ± 0.1 mGy, UHR kernel Ur77). For PCD-CT matched radiation dose, reconstruction kernel Br89. Quantitative analyses of noise, CNR, trabecular and cortical sharpness, and bone volume fraction were conducted. Five radiologists evaluated the images for fracture visibility, fracture gap consolidation and image quality, and rated their confidence in the diagnosis.

RESULTS

The trabecular and cortical sharpness were superior in images obtained with PCD-CT compared with EID-CT. A successive reduction in trabecular bone volume fraction during the immobilized periods was found with both systems. Despite higher noise and lower CNR with PCD-CT, radiologists rated the image quality of PCD-CT as superior. The visibility of the fracture line within 1-week post-trauma was rated higher with PCD-CT as was diagnostic confidence, but the subsequent assessments of fracture gap consolidation during healing process and the confidence in diagnosis were found equivalent between both systems.

CONCLUSION

PCD-CT offers superior visibility of bone microstructure compared with EID-CT. The evaluation of fracture healing and confidence in diagnosis were rated equally with both systems, but the radiologists found primary fracture visibility and overall image quality superior with PCD-CT.

Erianin serves as an NFATc1 inhibitor to prevent breast cancer-induced osteoclastogenesis and bone destruction

INTRODUCTION

Breast cancer-related bone metastasis can lead to skeletal-related events (SREs), which decrease patient quality of life. Inhibition of osteoclastogenesis is a key treatment for SREs; however, the availability of clinical drugs remains limited, and all existing ones disrupt physiological bone formation, while exhibiting no effect on patient survival time.

OBJECTIVES

This study aimed to identify a novel osteoclast inhibitor for the treatment of breast cancer-induced SREs.

METHODS

The MDA-MB-231 breast cancer cell-induced bone loss model was used to investigate the therapeutic effects of erianin in vivo. Then, we evaluated the inhibitory effects of erianin on osteoclastogenesis and signalling in bone marrow-derived macrophages (BMMs) induced by conditioned medium from MDA-MB-231 breast cancer cells (231 CM) and receptor activator of nuclear factor-κB ligand (RANKL) in vitro. Next, a Cellular Thermal Shift Assay and siRNA-mediate knockdown were performed, to investigate the target of erianin during osteoclast formation. The effects of erianin on human osteoclastogenesis were evaluated using CD14+ monocytes obtained from patients with breast cancer.

RESULTS

Erianin effectively improved breast cancer cells-induced bone destruction at doses of 2 and 20 mg/kg/day in vivo, while suppressing osteoclastogenesis and the upregulation of SRC-NFATc1, INTEGRIN β3-MMP9 signals induced by 231 CM and RANKL in vitro. Furthermore, erianin interacted with NFATc1 but not SRC, and Nfatc1 knockdown eliminated the inhibitory effects of erianin on osteoclastogenesis. Notably, lower expression of NFATc1 positively correlated with longer survival in patients with cancer and a high risk of bone metastasis. We further revealed that 62.5-250 nM erianin suppresses NFATc1 and excessive osteoclastogenesis in CD14+ monocytes from patients with breast cancer.

CONCLUSION

Erianin acts as an NFATc1 inhibitor that attenuates breast cancer-induced osteoclastogenesis and bone destruction.

β-Receptor blocker enhances the anabolic effect of PTH after osteoporotic fracture

The autonomic nervous system plays a crucial role in regulating bone metabolism, with sympathetic activation stimulating bone resorption and inhibiting bone formation. We found that fractures lead to increased sympathetic tone, enhanced osteoclast resorption, decreased osteoblast formation, and thus hastened systemic bone loss in ovariectomized (OVX) mice. However, the combined administration of parathyroid hormone (PTH) and the β-receptor blocker propranolol dramatically promoted systemic bone formation and osteoporotic fracture healing in OVX mice. The effect of this treatment is superior to that of treatment with PTH or propranolol alone. In vitro, the sympathetic neurotransmitter norepinephrine (NE) suppressed PTH-induced osteoblast differentiation and mineralization, which was rescued by propranolol. Moreover, NE decreased the PTH-induced expression of Runx2 but enhanced the expression of Rankl and the effect of PTH-stimulated osteoblasts on osteoclastic differentiation, whereas these effects were reversed by propranolol. Furthermore, PTH increased the expression of the circadian clock gene Bmal1, which was inhibited by NE-βAR signaling. Bmal1 knockdown blocked the rescue effect of propranolol on the NE-induced decrease in PTH-stimulated osteoblast differentiation. Taken together, these results suggest that propranolol enhances the anabolic effect of PTH in preventing systemic bone loss following osteoporotic fracture by blocking the negative effects of sympathetic signaling on PTH anabolism.

An Update on Drug-Nutrient Interactions and Dental Decay in Older Adults

In recent decades, the global demographic landscape has undergone a discernible shift that has been characterised by a progressive increase in the proportion of elderly individuals, indicative of an enduring global inclination toward extended lifespans. The aging process, accompanied by physiological changes and dietary patterns, contributes to detrimental deviations in micronutrient consumption. This vulnerable aging population faces heightened risks, including dental caries, due to structural and functional modifications resulting from insufficient nutritional sustenance. Factors such as physiological changes, inadequate nutrition, and the prevalence of multiple chronic pathologies leading to polypharmacy contribute to the challenge of maintaining an optimal nutritional status. This scenario increases the likelihood of drug interactions, both between medications and with nutrients and the microbiome, triggering complications such as dental decay and other pathologies. Since the drug industry is evolving and new types of food, supplements, and nutrients are being designed, there is a need for further research on the mechanisms by which drugs interfere with certain nutrients that affect homeostasis, exemplified by the prevalence of caries in the mouths of older adults. Infectious diseases, among them dental caries, exert serious impacts on the health and overall quality of life of the elderly demographic. This comprehensive review endeavours to elucidate the intricate interplay among drugs, nutrients, the microbiome, and the oral cavity environment, with the overarching objective of mitigating the potential hazards posed to both the general health and dental well-being of older adults. By scrutinising and optimising these multifaceted interactions, this examination aims to proactively minimise the susceptibility of the elderly population to a spectrum of health-related issues and the consequences associated with dental decay.

Regulation of Bone by Mechanical Loading, Sex Hormones, and Nerves: Integration of Such Regulatory Complexity and Implications for Bone Loss during Space Flight and Post-Menopausal Osteoporosis

During evolution, the development of bone was critical for many species to thrive and function in the boundary conditions of Earth. Furthermore, bone also became a storehouse for calcium that could be mobilized for reproductive purposes in mammals and other species. The critical nature of bone for both function and reproductive needs during evolution in the context of the boundary conditions of Earth has led to complex regulatory mechanisms that require integration for optimization of this tissue across the lifespan. Three important regulatory variables include mechanical loading, sex hormones, and innervation/neuroregulation. The importance of mechanical loading has been the target of much research as bone appears to subscribe to the "use it or lose it" paradigm. Furthermore, because of the importance of post-menopausal osteoporosis in the risk for fractures and loss of function, this aspect of bone regulation has also focused research on sex differences in bone regulation. The advent of space flight and exposure to microgravity has also led to renewed interest in this unique environment, which could not have been anticipated by evolution, to expose new insights into bone regulation. Finally, a body of evidence has also emerged indicating that the neuroregulation of bone is also central to maintaining function. However, there is still more that is needed to understand regarding how such variables are integrated across the lifespan to maintain function, particularly in a species that walks upright. This review will attempt to discuss these regulatory elements for bone integrity and propose how further study is needed to delineate the details to better understand how to improve treatments for those at risk for loss of bone integrity, such as in the post-menopausal state or during prolonged space flight.

Circulating miR-340-5p and miR-506-3p as Two Osteo-miRNAs for Predicting Osteoporosis in a Cohort of Postmenopausal Women

Objective

An increasing risk of developing osteoporosis which is characterized by bone production weakness and microarchitectural deterioration is found among postmenopausal women. MicroRNAs (miRNAs) are secreted into the circulation from cells of various tissues in response to local disease severity including bone diseases. Herein, we set out to identify candidate miRNAs predictable for osteoporosis incidence in postmenopausal elderly women.

Methods

The circulating miRNA expression profiles deposited in the dataset accessioned as GSE201543 were downloaded from the GEO database. The study included 176 postmenopausal women who underwent BMD testing, including 96 women reporting osteoporosis and 70 women reporting normal BMD. All subjects were submitted their serum samples for measurements of bone metabolism markers.

Results

The miRNA expression profiles of the GSE201543 dataset were differentially analyzed and found 97 miRNAs being upregulated concomitantly with 31 miRNAs being downregulated in the serum samples between osteoporotic postmenopausal women and postmenopausal women with normal BMD. Osteoporotic postmenopausal women were demonstrated with elevated serum levels of miR-340-5p and miR-506-3p when compared to normal postmenopausal women. Pearson correlation analysis demonstrated that circulating miR-340-5p and miR-506-3p expressions were increased as BAP, β-CTx, and PINP levels increased, but osteocalcin and 25-(OH)VitD levels are declined in osteoporotic postmenopausal women. Results of the receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC) showed circulating miR-340-5p and miR-506-3p expressions alone or combined together produced 0.843 AUC, 0.851 AUC, and 0.935 AUC, respectively, when used to predict the incidence of osteoporosis in postmenopausal women.

Conclusion

Our work suggested that circulating miR-340-5p and miR-506-3p function as osteo-miRNAs in postmenopausal women and may serve as potential noninvasive biomarkers for the incidence of osteoporosis in postmenopausal women.