Promotion of Bone Formation in a Rat Osteoporotic Vertebral Body Defect Model via Suppression of Osteoclastogenesis by Ectopic Embryonic Calvaria Derived Mesenchymal Stem Cells.

Osteoporotic vertebral compression fractures (OVCFs) are the most prevalent fractures among patients with osteoporosis, leading to severe pain, deformities, and even death. This study explored the use of ectopic embryonic calvaria derived mesenchymal stem cells (EE-cMSCs), which are known for their superior differentiation and proliferation capabilities, as a potential treatment for bone regeneration in OVCFs. We evaluated the impact of EE-cMSCs on osteoclastogenesis in a RAW264.7 cell environment, which was induced by the receptor activator of nuclear factor kappa-beta ligand (RANKL), using cytochemical staining and quantitative real-time PCR. The osteogenic potential of EE-cMSCs was evaluated under various hydrogel conditions. An osteoporotic vertebral body bone defect model was established by inducing osteoporosis in rats through bilateral ovariectomy and creating defects in their coccygeal vertebral bodies. The effects of EE-cMSCs were examined using micro-computed tomography (µCT) and histology, including immunohistochemical analyses. In vitro, EE-cMSCs inhibited osteoclast differentiation and promoted osteogenesis in a 3D cell culture environment using fibrin hydrogel. Moreover, µCT and histological staining demonstrated increased new bone formation in the group treated with EE-cMSCs and fibrin. Immunostaining showed reduced osteoclast activity and bone resorption, alongside increased angiogenesis. Thus, EE-cMSCs can effectively promote bone regeneration and may represent a promising therapeutic approach for treating OVCFs.

Potential Metabolic Pathways Involved in Osteoporosis and Evaluation of Fracture Risk in Individuals with Diabetes.

Diabetes has a significant global prevalence. Chronic hyperglycemia affects multiple organs and tissues, including bones. A large number of diabetic patients develop osteoporosis; however, the precise relationship between diabetes and osteoporosis remains incompletely elucidated. The activation of the AGE-RAGE signaling pathway hinders the differentiation of osteoblasts and weakens the process of bone formation due to the presence of advanced glycation end products. High glucose environment can induce ferroptosis of osteoblasts and then develop osteoporosis. Hyperglycemia also suppresses the secretion of sex hormones, and the reduction of testosterone is difficult to effectively maintain bone mineral density. As diabetes therapy, thiazolidinediones control blood glucose by activating PPAR-γ. Activated PPAR-γ can promote osteoclast differentiation and regulate osteoblast function, triggering osteoporosis. The effects of metformin and insulin on bone are currently controversial. Currently, there are no appropriate tools available for assessing the risk of fractures in diabetic patients, despite the fact that the occurrence of osteoporotic fractures is considerably greater in diabetic individuals compared to those without diabetes. Further improving the inclusion criteria of FRAX risk factors and clarifying the early occurrence of osteoporosis sites unique to diabetic patients may be an effective way to diagnose and treat diabetic osteoporosis and reduce the risk of fracture occurrence.

Hypoxia preconditioning of adipose stem cell-derived exosomes loaded in gelatin methacryloyl (GelMA) promote type H angiogenesis and osteoporotic fracture repair.

The challenges posed by delayed atrophic healing and nonunion stand as formidable obstacles in osteoporotic fracture treatment. The processes of type H angiogenesis and osteogenesis emerge as pivotal mechanisms during bone regeneration. Notably, the preconditioning of adipose-derived stem cell (ADSC) exosomes under hypoxic conditions has garnered attention for its potential to augment the secretion and functionality of these exosomes. In the present investigation, we embarked upon a comprehensive elucidation of the underlying mechanisms of hypo-ADSC-Exos within the milieu of osteoporotic bone regeneration. Our findings revealed that hypo-ADSC-Exos harboured a preeminent miRNA, namely, miR-21-5p, which emerged as the principal orchestrator of angiogenic effects. Through in vitro experiments, we demonstrated the capacity of hypo-ADSC-Exos to stimulate the proliferation, migration, and angiogenic potential of human umbilical vein endothelial cells (HUVECs) via the mediation of miR-21-5p. The inhibition of miR-21-5p effectively attenuated the proangiogenic effects mediated by hypo-ADSC-Exos. Mechanistically, our investigation revealed that exosomal miR-21-5p emanating from hypo-ADSCs exerts its regulatory influence by targeting sprouly1 (SPRY1) within HUVECs, thereby facilitating the activation of the PI3K/AKT signalling pathway. Notably, knockdown of SPRY1 in HUVECs was found to potentiate PI3K/AKT activation and, concomitantly, HUVEC proliferation, migration, and angiogenesis. The culminating stage of our study involved a compelling in vivo demonstration wherein GelMA loaded with hypo-ADSC-Exos was validated to substantially enhance local type H angiogenesis and concomitant bone regeneration. This enhancement was unequivocally attributed to the exosomal modulation of SPRY1. In summary, our investigation offers a pioneering perspective on the potential utility of hypo-ADSC-Exos as readily available for osteoporotic fracture treatment.

A Bone-Penetrating Precise Controllable Drug Release System Enables Localized Treatment of Osteoporotic Fracture Prevention via Modulating Osteoblast-Osteoclast Communication.

Improving local bone mineral density (BMD) at fracture-prone sites of bone is a clinical concern for osteoporotic fracture prevention. In this study, a featured radial extracorporeal shock wave (rESW) responsive nano-drug delivery system (NDDS) is developed for local treatment. Based on a mechanic simulation, a sequence of hollow zoledronic acid (ZOL)-contained nanoparticles (HZNs) with controllable shell thickness that predicts various mechanical responsive properties is constructed by controlling the deposition time of ZOL and Ca2+ on liposome templates. Attributed to the controllable shell thickness, the fragmentation of HZNs and the release of ZOL and Ca2+ can be precisely controlled with the intervention of rESW. Furthermore, the distinct effect of HZNs with different shell thicknesses on bone metabolism after fragmentation is verified. In vitro co-culture experiments demonstrate that although HZN2 does not have the strongest osteoclasts inhibitory effect, the best pro-osteoblasts mineralization results are achieved via maintaining osteoblast-osteoclast (OB-OC) communication. In vivo, the HZN2 group also shows the strongest local BMD enhancement after rESW intervention and significantly improves bone-related parameters and mechanical properties in the ovariectomy (OVX)-induced osteoporosis (OP) rats. These findings suggest that an adjustable and precise rESW-responsive NDDS can effectively improve local BMD in OP therapy.

Integrated Analysis of Crucial Genes and miRNAs Associated with Osteoporotic Fracture of Type 2 Diabetes.

Purpose: The aim of this study is to explore pathological mechanisms of bone fragility in type 2 diabetes mellitus (T2DM) patients. Methods: Identifying common genes for T2DM and osteoporosis by taking the intersection is shared by the Comparative Toxicogenomics Database (CTD), DISEASES, and GeneCards databases. The differentially expressed genes (DEGs) and the differentially expressed miRNAs (DEMs) were identified by analyzing the Gene Expression Omnibus (GEO) datasets (GSE35958, GSE43950, and GSE70318). FunRich and miRNet were applied to predict potential upstream transcription factors and downstream target genes of candidate DEMs, respectively. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to explore potential mechanisms using Metascape. Eventually, a miRNA-gene network was constructed by Cytoscape software. Results: 271 common targets and 35 common DEGs between T2DM and osteoporosis were screened out in the above databases, and a total of ten DEMs were obtained in the GSE70318. SP1 was predicted to potentially regulate most of the DEMs. Enrichment analysis showed the PI3K-Akt signaling pathway and AGE-RAGE signaling pathway in diabetic complications may play an important role in diabetic skeletal fragility. Two genes (NAMPT and IGFBP5) were considered as key genes involving in the development of diabetic osteoporosis. Through the construction of the miRNA-gene network, most of the hub genes were found to be potentially modulated by miR-96-5p and miR-7-5p. Conclusion: The study uncovered several important genes, miRNAs, and pathological mechanisms involved in diabetic skeletal fragility, among which the PI3K-Akt signaling pathway and AGE-RAGE signaling pathway in diabetic complications may play important roles.

Role of nitric oxide in type 1 diabetes-induced osteoporosis.

Type 1 diabetes (T1D)-induced osteoporosis is characterized by decreased bone mineral density, bone quality, rate of bone healing, bone formation, and increased bone resorption. Patients with T1D have a 2-7-fold higher risk of osteoporotic fracture. The mechanisms leading to increased risk of osteoporotic fracture in T1D include insulin deficiency, hyperglycemia, insulin resistance, lower insulin-like growth factor-1, hyperglycemia-induced oxidative stress, and inflammation. In addition, a higher probability of falling, kidney dysfunction, weakened vision, and neuropathy indirectly increase the risk of osteoporotic fracture in T1D patients. Decreased nitric oxide (NO) bioavailability contributes to the pathophysiology of T1D-induced osteoporotic fracture. This review discusses the role of NO in osteoblast-mediated bone formation and osteoclast-mediated bone resorption in T1D. In addition, the mechanisms involved in reduced NO bioavailability and activity in type 1 diabetic bones as well as NO-based therapy for T1D-induced osteoporosis are summarized. Available data indicates that lower NO bioavailability in diabetic bones is due to disruption of phosphatidylinositol 3­kinase/protein kinase B/endothelial NO synthases and NO/cyclic guanosine monophosphate/protein kinase G signaling pathways. Thus, NO bioavailability may be boosted directly or indirectly by NO donors. As NO donors with NO-like effects in the bone, inorganic nitrate and nitrite can potentially be used as novel therapeutic agents for T1D-induced osteoporosis. Inorganic nitrites and nitrates can decrease the risk for osteoporotic fracture probably directly by decreasing osteoclast activity, decreasing fat accumulation in the marrow cavity, increasing osteoblast activity, and increasing bone perfusion or indirectly, by improving hyperglycemia, insulin resistance, and reducing body weight.

Associations of Age at Menopause With Postmenopausal Bone Mineral Density and Fracture Risk in Women.

CONTEXT: Menopause before age 45 is a risk factor for fractures, but menopause occurs at age ≥45 in ~90% of women. OBJECTIVE: To determine, in women with menopause at age ≥45, whether (1) years since the final menstrual period (FMP) is more strongly associated with postmenopausal bone mineral density (BMD) than chronological age and (2) lower age at FMP is related to more fractures. DESIGN AND SETTING: The Study of Women's Health Across the Nation, a longitudinal cohort study of the menopause transition (MT). PARTICIPANTS: A diverse cohort of ambulatory women (pre- or early perimenopausal at baseline, with 15 near-annual follow-up assessments). MAIN OUTCOME MEASURES: Postmenopausal lumbar spine (LS) or femoral neck (FN) BMD (n = 1038) and time to fracture (n = 1554). RESULTS: Adjusted for age, body mass index (BMI), cigarette use, alcohol intake, baseline LS or FN BMD, baseline MT stage, and study site using multivariable linear regression, each additional year after the FMP was associated with 0.006 g/cm2 (P < 0.0001) and 0.004 g/cm2 (P < 0.0001) lower postmenopausal LS and FN BMD, respectively. Age was not related to FN BMD independent of years since FMP. In Cox proportional hazards regression, accounting for race/ethnicity, BMI, cigarette use, alcohol intake, prior fracture, diabetes status, exposure to bone-modifying medications/supplements, and study site, the hazard for incident fracture was 5% greater for each 1-year decrement in age at FMP (P = 0.02). CONCLUSIONS: Years since the FMP is more strongly associated with postmenopausal BMD than chronological age, and earlier menopause is associated with more fractures.

Implantable Electrical Stimulation at Dorsal Root Ganglions Accelerates Osteoporotic Fracture Healing via Calcitonin Gene-Related Peptide.

The neuronal engagement of the peripheral nerve system plays a crucial role in regulating fracture healing, but how to modulate the neuronal activity to enhance fracture healing remains unexploited. Here it is shown that electrical stimulation (ES) directly promotes the biosynthesis and release of calcitonin gene-related peptide (CGRP) by activating Ca2+ /CaMKII/CREB signaling pathway and action potential, respectively. To accelerate rat femoral osteoporotic fracture healing which presents with decline of CGRP, soft electrodes are engineered and they are implanted at L3 and L4 dorsal root ganglions (DRGs). ES delivered at DRGs for the first two weeks after fracture increases CGRP expression in both DRGs and fracture callus. It is also identified that CGRP is indispensable for type-H vessel formation, a biological event coupling angiogenesis and osteogenesis, contributing to ES-enhanced osteoporotic fracture healing. This proof-of-concept study shows for the first time that ES at lumbar DRGs can effectively promote femoral fracture healing, offering an innovative strategy using bioelectronic device to enhance bone regeneration.

Asymptomatic morphometric vertebral fractures and its associated factors: A cross-sectional study among adults in a selected urban area in Selangor, Malaysia.

OBJECTIVE: This study aimed to determine the prevalence of vertebral fractures (VF) in a selected urban population in Malaysia and to explore possible variables associated with VF in the study population. METHODS: A cross-sectional study involving community-living, healthy subjects aged between 45-90 years from the state of Selangor, Malaysia, were invited to attend a bone health check-up. Subjects with diseases known to affect bone metabolism or were on treatment for osteoporosis (OP) were excluded. Bone mineral density (BMD) was measured using dual energy X-ray absorptiometry (DXA). Lateral and antero-posterior view lumbar spine x-rays were performed and VF was determined by the semi-quantitative Genant method. RESULTS: A total of 386 subjects were studied. Asymptomatic morphometric VF were found in 44 (11.4%) subjects. T12 was the most common vertebrae to be fractured. The prevalence of VF was significantly higher in menopausal women (12.4%) compared to non-menopausal women, in those above the age of 60 (18.5%), in those of Chinese ethnicity (16.5%), in those with a low body fat percentage (17.1%) and among those with OP (27.0%). The mean (standard deviation) 25-hydroxyvitamin D [25(OH)D] levels were significantly higher in those with VF compared to those without VF, 67.64 (23.50) and 57.47 (21.71) nmol/L, respectively. However, after multiple regression analysis, age over 60 years and OP on DXA BMD measurement were the only significant associated factors for VF. CONCLUSION: Overall, 11.4% of a selected Malaysian urban population had asymptomatic morphometric VF. Age over 60 years and OP on DXA BMD measurement, but not 25(OH)D levels, were associated with VF.

Exosomes: A Friend or Foe for Osteoporotic Fracture?

The clinical need for effective osteoporotic fracture therapy and prevention remains urgent. The occurrence and healing of osteoporotic fracture are closely associated with the continuous processes of bone modeling, remodeling, and regeneration. Accumulating evidence has indicated a prominent role of exosomes in mediating multiple pathophysiological processes, which are essential for information and materials exchange and exerting pleiotropic effects on neighboring or distant bone-related cells. Therefore, the exosomes are considered as important candidates both in the occurrence and healing of osteoporotic fracture by accelerating or suppressing related processes. In this review, we collectively focused on recent findings on the diagnostic and therapeutic applications of exosomes in osteoporotic fracture by regulating osteoblastogenesis, osteoclastogenesis, and angiogenesis, providing us with novel therapeutic strategies for osteoporotic fracture in clinical practice.

Effects of BMP-2 compound with fibrin on osteoporotic vertebral fracture healing in rats.

OBJECTIVES: To investigate the effects of bone morphogenetic protein-2 (BMP-2) compound with fibrin on osteoporotic vertebral fracture healing in rats. METHODS: For the present study 160 Specific-Pathogen Free 32-week-old female Sprague-Dawley rats were used. 120 rats were randomly divided in three groups (experimental, model and sham operation group- n=40 per group) and were ovariectomized to establish the osteoporosis model. 40 rats served as a control group without treatment. The expression of BMP-2 in the fracture zone at the 4th, 6th, 8th, and 12th weeks was detected by qRT-PCR. The expression of BALP and CTX-I in serum at the 12th week was detected by Elisa. RESULTS: At week 8, the morphology of the sham operation group was the same and the fracture healing occurred more slowly than in the other groups. At week 12, the expression of BMP-2 in the model group was significantly higher than that in the other three groups (p<0.05). At week 12, the maximum load, maximum strain, and elastic modulus of model group were significantly lower than those of the other three groups. CONCLUSIONS: BMP-2 compound with fibrin can enhance the timing and quality of bone fracture healing in rats.

Vertebral compression fractures: Still an unpredictable aspect of osteoporosis

Vertebral compression fracture is a hallmark of osteoporosis (OP) and by far the most prevalent fragility fracture. It is well proven that patients who develop a vertebral compression fracture are at substantial risk for additional fractures. Diagnosis is based on adequate clinical evaluation, imaging, and laboratory tests. The imaging of OP and fragility fractures includes conventional radiology to evaluate spinal fractures, bone mineral density (BMD) testing by dual energy x-ray densitometry, quantitative computerized tomography, magnetic resonance imaging, bone scintigraphy (if necessary), and ultrasound. Screening and treatment of individuals with high risk of osteoporotic fracture are cost-effective, but approximately two-thirds of the vertebral compression fractures (VCF) that occur each year are not accurately diagnosed and, therefore, not treated. Evaluation of VCFs, even though they may be asymptomatic, seems essential to health-related and/or clinical research on OP.

Serum MicroRNA Differences Between Fracture in Postmenopausal Women with and without Diabetes.

OBJECTIVE: To screen serum microRNAs (miRNAs) which could discriminate fracture status in postmenopausal women with or without diabetes. METHODS: The miRNA expression profile dataset GSE70318 was downloaded from Gene Expression Omnibus (GEO) database. This dataset composed of 74 samples, among these, 55 postmenopausal women was selected for bioinformatics analysis, including 19 osteoporotic fracture patients with type-2 diabetes, 19 osteoporotic fracture patients without type-2 diabetes, and 17 healthy control subjects. These samples were divided into two groups: fracture patients with diabetes vs healthy subjects (FH group) and fracture patients without diabetes vs healthy subjects (DFH group). Then, the differentially expressed miRNA (DEMs) in FH group and DFH group were respectively identified. The target genes of DEMs were predicted, followed by functional enrichment analysis. Furthermore, DEMs related to long non-coding RNAs (lncRNAs) were screened, and DEMs-lncRNA-target genes network was constructed. Subsequently, principal component analysis (PCA) of DEMs was performed to further explore the expression characteristics of the selected miRNAs in different types of fracture samples. Finally, the expression level of significant DEMs was calculated by quantitative real-time polymerase chain reaction (qPCR) to verify the accuracy of the results of bioinformatics analysis. RESULTS: A total of 18 and 23 DEMs were identified in FH and DFH groups, respectively. Gene ontology (GO) analysis showed that genes in FH group were significantly enriched in regulation of transcription (GO: 0045449) and genes in DFH group were mainly enriched in cellular response to hormone stimulus (GO: 0032870). Meanwhile, pathway analysis indicated that genes in FH group were primarily enriched in T cell receptor signaling pathway (hsa04660) and genes in DFH group were mainly implicated in neurotrophin-signaling pathway (hsa04722). Moreover, the miRNA-lncRNA analysis revealed that miR-155-5p regulated by lncRNA MIR155HG was up-regulated in FH group; in addition, the miR-181c was significantly up-regulated and miR-375 was observably down-regulated in DFH group. Furthermore, PCA analysis suggested that the screened miRNAs were able to differentiate these two types of fractures in postmenopausal women. The miR-181c and miR-375 might be regarded as potential predictors for fracture, while miR-155-5p might be a candidate diagnostic biomarker for diabetic fracture. Finally, the results of qPCR were consistent with that of microarray data. CONCLUSIONS: Overall, these three miRNAs might be regarded as potential diagnostic biomarkers to discriminate fracture status in postmenopausal women with and or without diabetes, and they served a putative role in the pathogenesis of these two diseases. However, these findings were only observed in serum samples and further clinical trials are urgently demanded to validate our results.

Associations of LRP5 Gene With Bone Mineral Density, Bone Turnover Markers, and Fractures in the Elderly With Osteoporosis.

Objective: The study aimed to explore the associations of rs4988300 and rs634008 in the low-density lipoprotein receptor-related protein 5 (LRP5) gene with bone mineral density (BMD), bone turnover markers (BTM), and fractures in elderly patients with osteoporosis (OP). Methods: Our study included 328 unrelated OP patients with or without fractures. Genomic DNA was extracted for genotyping. BTM levels were assessed by electrochemiluminescence (ECL). Dual-energy X-ray absorptiometry (DXA) was employed to measure BMD in the lumbar spine (LS) and proximal femur. Basic features between the OP and fracture groups were analyzed using the t-test. The Chi-square test was performed to analyze the differences in allele and genotype frequencies. The associations of single-nucleotide polymorphisms (SNPs) with BMD and BTM in the subgroups were investigated by the analysis of covariance (ANCOVA) adjusted for confounding factors. Results: In both females and males, individuals with fractures exhibited higher BTM levels and lower BMD values than those with OP (P < 0.05). The allele and genotype frequencies of rs4988300 in the subgroups were significantly different (P < 0.05). In both females and males suffering from OP, participants with rs4988300 GG or rs634008 TT presented lower procollagen I N-terminal propeptide (PINP) levels (P < 0.05). Women with OP carrying rs4988300 GG exhibited lower BMD values at FN and TH (P < 0.05). In both females and males with fractures, individuals carrying rs4988300 GG genotype or rs634008 TT genotype exhibited lower PINP levels and BMD values at FN and TH than those with other genotypes (P < 0.05). Conclusions: Rs4988300 and rs634008 polymorphisms in the LRP5 gene are associated with bone phenotypes in the elderly with OP or fractures.

MiR-214 regulates fracture healing through inhibiting Sox4 and its mechanism.

OBJECTIVE: To investigate the expression of micro ribonucleic acid (miR)-214 in the bone tissue and blood of patients with fragility fracture. METHODS: The expression of miR-214 was detected via quantitative reverse transcription-polymerase chain reaction. The effect of miR-214 on proliferation and apoptosis of osteoblasts were detected via methyl thiazolyl tetrazolium assay and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining. RESULTS: The expression of miR-214 in the bone tissue and blood of patients with fragility fracture significantly declined. miR-214 could promote the proliferation of osteoblasts and inhibited the apoptosis of osteoblasts. miR-214 is involved in fracture healing through inhibiting Sox4 and promoting phosphorylation of PI3K/AKT pathway. The expression of BSP in cells treated with miR-214 mimics was significantly increased to 2.5-fold (p=0.0168), while the expression of BSP in cells treated with miR-214 AMO was significantly decreased, reduced to 0.3 times (p=0.0397). The expression of BMP2 in cells treated with miR-214 mimics was significantly increased to 2.5-fold (p=0.003), while the expression of BMP2 was significantly decreased in cells treated with miR-214 AMO, reduced to 0.3 times (p=0.0002). miR-214 can regulate the expression of Sox2, PI3K and AKT proteins. CONCLUSION: MiR-214 regulates the proliferation, apoptosis, bone formation of osteoblasts and participate in the fracture healing process by inhibiting the expression of Sox4, which provided new ideas for clinical treatment of fracture healing.

Overexpression of SNTG2, TRAF3IP2, and ITGA6 transcripts is associated with osteoporotic vertebral fracture in elderly women from community.

BACKGROUND: Vertebral fractures (VFs) are the most common clinical manifestation of osteoporosis associated with high morbimortality. A personal/familiar history of fractures increases the risk of fractures. The purpose of this study is to identify possible molecular markers associated with osteoporotic VFs in elderly women from community. METHODS: Transcriptomic analysis using Affymetrix HTA2 microarray was performed using whole blood samples of 240 subjects from a population-based survey (Sao Paulo Ageing & Health [SPAH] study). Only elderly women with osteoporosis diagnosis by densitometry were analyzed, and divided in two groups: VF: women with osteoporosis and VFs versus no vertebral fracture (NVF): women with osteoporosis and NVFs. They were matched for age, chronic disease, medication use, and bone mineral density (BMD). The logistic regression model adjusted for age was applied for transcriptome data analysis. SYBR green-based quantitative polymerase chain reaction (qPCR) was used to validate the most significant expression changes obtained in the microarray experiment. RESULTS: Microarray analysis identified 142 differentially expressed genes (DEGs, p < .01), 57 upregulated and 85 downregulated, compared VF versus NVF groups. The DEG with the greatest expression difference was the Gamma2-Syntrophin (SNTG2) (ß = 31.88, p = .005). Validation by qPCR confirmed increased expression in VF group of Syntrophin (SNTG2, fold change = 2.79, p = .009), TRAF3 Interacting Protein2 (TRAF3IP2, fold change = 2.79, p = .020), and Integrin Subunit Alpha 6 (ITGA6, fold change = 2.86, p = .038). CONCLUSION: Our data identified and validated the association of SNTG2 (608715), TRAF3IP2 (607043), and ITGA6 (147556) with osteoporotic VF in elderly women, independently of BMD. These results suggest that these transcripts have potential clinical significance and may help to explain the molecular mechanisms and biological functions of vertebral fracture.

Treatment-related changes in bone mineral density as a surrogate biomarker for fracture risk reduction: meta-regression analyses of individual patient data from multiple randomised controlled trials.

BACKGROUND: The validation of bone mineral density (BMD) as a surrogate outcome for fracture would allow the size of future randomised controlled osteoporosis registration trials to be reduced. We aimed to determine the association between treatment-related changes in BMD, assessed by dual-energy x-ray absorptiometry, and fracture outcomes, including the proportion of treatment effect explained by BMD changes. METHODS: We did a pooled analysis of individual patient data from multiple randomised placebo-controlled clinical trials. We included data from multicentre, randomised, placebo-controlled, double-blind trials of osteoporosis medications that included women and men at increased osteoporotic fracture risk. Using individual patient data for each trial we calculated mean 24-month BMD percent change together with fracture reductions and did a meta-regression of the association between treatment-related differences in BMD changes (percentage difference, active minus placebo) and fracture risk reduction. We also used individual patient data to determine the proportion of anti-fracture treatment effect explained by BMD changes and the BMD change needed in future trials to ensure fracture reduction efficacy. FINDINGS: Individual patient data from 91 779 participants of 23 randomised, placebo-controlled trials were included. The trials had 1-9 years of follow-up and included 12 trials of bisphosphonate, one of odanacatib, two of hormone therapy (one of conjugated equine oestrogen and one of conjugated equine oestrogen plus medroxyprogesterone acetate), three of PTH receptor agonists, one of denosumab, and four of selective oestrogen receptor modulator trials. The meta-regression revealed significant associations between treatment-related changes in hip, femoral neck, and spine BMD and reductions in vertebral (r2 0·73, p<0·0001; 0·59, p=0·0005; 0·61, p=0·0003), hip (0·41, p=0·014; 0·41, p=0·0074; 0·34, p=0·023) and non-vertebral fractures (0·53, p=0·0021; 0·65, p<0·0001; 0·51, p=0·0019). Minimum 24-month percentage changes in total hip BMD providing almost certain fracture reductions in future trials ranged from 1·42% to 3·18%, depending on fracture site. Hip BMD changes explained substantial proportions (44-67%) of treatment-related fracture risk reduction. INTERPRETATION: Treatment-related BMD changes are strongly associated with fracture reductions across randomised trials of osteoporosis therapies with differing mechanisms of action. These analyses support BMD as a surrogate outcome for fracture outcomes in future randomised trials of new osteoporosis therapies and provide an important demonstration of the value of public access to individual patient data from multiple trials. FUNDING: Foundation for National Institutes of Health.

Changes of Bone Turnover Markers and Bone Tissue Content After Severe Osteoporotic Vertebral Compression Fracture.

BACKGROUND The incidence of osteoporotic vertebral fractures (OVCFs) has increased significantly in recent years. In order to assess osteoporotic fracture healing process, it is necessary to study the characteristics after this type of vertebral fracture. However, there are few researches on fracture healing process in severe OVCFs. We aim to investigate the histological healing process and the kinetics of bone turnover markers following severe OVCFs. MATERIAL AND METHODS There were 149 patients with severe OVCFs included in this study. Fasting blood samples were obtained to detect bone turnover markers levels. A transpedicular bone biopsy was performed to collect bone biopsy specimens during vertebroplasty surgery. Stratification of healing process was performed: stage I (1-3 days), stage II (4-10 days), stage III (11-20 days), stage IV (21-30 days), stage V (1-3 months), stage VI (3-6 months). RESULTS Quantitative analysis of bone histomorphometry showed that a large amount of necrotic bone tissue was observed in stage VI (12.92±3.66%). Bone turnover markers showed the concentration of ß-isomerized C-terminal telopeptide (ß-CTX) which reflects activity in osteoclast continued to increase in stage VI (0.9±0.33 ng/mL). These results differed from previous reports of other type vertebral fractures. CONCLUSIONS Bone histomorphometric analysis and bone turnover markers showed that severe osteoporotic vertebral compression fractures often associated with delayed union and nonunion during the healing process.