Delayed Fracture Healing

[Influencing fracture healing by specific osteoporosis medications]

BACKGROUND

Osteoporosis is a widespread disease defined by a reduction 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 a strategy to promote the healing of impaired fractures.

OBJECTIVE

The aim of this study is to provide a current 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.

MATERIAL AND METHODS

A literature 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.

RESULTS

Preclinical and clinical studies suggest that specific osteoporosis medications do not have a clinically relevant negative impact on the healing of fragility fractures. Osteoanabolic substances even tend to have a positive 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.

DISCUSSION

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.

FBN2 promotes the proliferation, mineralization, and differentiation of osteoblasts to accelerate fracture healing

Fracture is a disease in which the continuity of bone is interrupted or the integrity of bone is destroyed due to various reasons. It can be life-threatening when severe fractures occur. The RNA-seq datasets related to 'fracture' were screened and the common differentially expressed genes (DEGs) were determined. Protein-protein interaction network was constructed to identify hub genes. The fracture mice model was constructed and HE staining was performed to observe the histological characteristics of fracture. The expression of inflammatory factors and hub genes were evaluated by ELISA and qRT-PCR. CCK-8 assay, flow cytometry and Alizarin Red S staining were performed to evaluate the effects of fibrillin2(FBN2) on viability, apoptosis and mineralization of MC3T3E1 cells, respectively. Western blot was executed to measure expression of osteogenic markers (ALP and RUNX2). A total of 78 common DEGs were screened from GSE157460 and GSE152677 datasets. FBN2 was down-regulated in fracture and identified as the hub gene. In fracture mice, the thickness of the compact bone decreased in Day 1, accompanied by callus and woven bone formation, filled with a large number of osteoblasts, while IL-1β, IL-6 and TNF-α levels were increased. FBN2 enhanced cell viability and mineralization, suppresses apoptosis of MC3T3E1 cells, and facilitated the expression of ALP and RUNX2. Meanwhile, the knockdown of FBN2 demonstrated opposing trends. Through bioinformatics analysis, FBN2 was identified as the hub gene in fracture, and FBN2 promoted the proliferation, mineralization, and differentiation of osteoblasts, thereby accelerating fracture healing.

The relationship between the expression of serum asprosin and miR-21 in patients with osteoporosis and delayed healing after OVCF surgery

Objective: To explore the relationship between serum asprosin, microRNA-21 (miR-21) expression, and delayed healing after surgery in patients with osteoporotic vertebral compression fractures (OVCF), and to construct a nomogram model. Methods: A prospective study inducted 300 OVCF patients treated with percutaneous vertebroplasty (PVP) from June 2022 to June 2024. Serum asprosin and miR-21 were measured preoperatively, and fracture healing was assessed via X-ray 3 months post-surgery. Patients were categorized into delayed healing and normal healing groups based on outcomes. The least absolute shrinkage and selection algorithm (LASSO) regression identified factors influencing delayed healing, followed by binary logistic regression analysis. A nomogram model was constructed to predict delayed healing, and its predictive value was evaluated using the receiver operating curve (ROC) analysis. Results: Results showed higher rates of delayed weight-bearing (58.11% vs 33.19%), diabetes prevalence (52.70% vs 42.48%), bone cement injection volume (4.68 ± 1.14 mL vs 3.81 ± 1.09 mL), and serum asprosin levels (4.09 ± 1.39 ng/mL vs 3.14 ± 1.07 ng/mL) in the delayed healing group compared to the normal healing group. Serum miR-21 levels were lower in the delayed healing group (0.69 ± 0.19) than in the normal group (0.92 ± 0.31) (p < 0.05). Bone density T scores in OVCF patients correlated positively with asprosin (r = 0.281, p < 0.001) and negatively with miR-21 (r = -0.184, p = 0.001). The LASSO regression identified five factors associated with delayed healing: bone cement volume, delayed weight-bearing, diabetes, and serum asprosin (risk factors), while high miR-21 was protective. Logistic regression indicated significant risk factors with an overall C-index of 0.867 and AUC of 0.868 (sensitivity 0.892, specificity 0.686). After 3 months of treatment, serum Asprosin [(3.46 ± 1.22) ng/ml] in OVCF patients was lower than that before treatment [(3.03 ± 1.03) ng/ml], and serum miR-21 (0.85 ± 0.30) was higher than that before treatment [(0.99 ± 0.33)] (t = 4.039, 4.318, p < 0.05). Conclusion: Serum asprosin and miR-21 levels are closely related to delayed healing after surgery in patients with OVCF. Additionally, the bone cement injection volume, delayed weight-bearing, and concomitant diabetes mellitus are also important factors affecting fracture healing in patients. The nomogram model based on these factors can effectively predict the risk of delayed healing in patients with OVCF after surgery.

Bioinformatics Analysis and Experimental Validation of Differential Genes and Pathways in Bone Nonunions

Non-union fractures pose a significant clinical challenge, often leading to prolonged pain and disability. Understanding the molecular mechanisms underlying non-union fractures is crucial for developing effective therapeutic interventions. This study integrates bioinformatics analysis and experimental validation to unravel key genes and pathways associated with non-union fractures. We identified differentially expressed genes (DEGs) between non-union and fracture healing tissues using bioinformatics techniques. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were employed to elucidate the biological processes and pathways involved. Common DEGs were identified, and a protein-protein interaction (PPI) network was constructed. Fibronectin-1 (FN1), Thrombospondin-1 (THBS1), and Biglycan (BGN) were pinpointed as critical target genes for non-union fracture treatment. Experimental validation involved alkaline phosphatase (ALP) and Alizarin Red staining to confirm osteogenic differentiation. Our analysis revealed significant alterations in pathways related to cell behavior, tissue regeneration, wound healing, infection, and immune responses in non-union fracture tissues. FN1, THBS1, and BGN were identified as key genes, with their upregulation indicating potential disruptions in the bone remodeling process. Experimental validation confirmed the induction of osteogenic differentiation. The study provides comprehensive insights into the molecular mechanisms of non-union fractures, emphasizing the pivotal roles of FN1, THBS1, and BGN in extracellular matrix dynamics and bone regeneration. The findings highlight potential therapeutic targets and pathways for further investigation. Future research should explore interactions between these genes, validate results using in vivo fracture models, and develop tailored treatment strategies for non-union fractures, promising significant advances in clinical management.

Enhancing Osteoblast Activity and Accelerating Fracture Healing via miR-656-3p Downregulation: A Novel Targeting Strategy Focused on BMP-2 Expression

Delayed fracture healing (DFH), a common complication of post-fracture surgery, exhibits an incompletely understood pathogenesis. The present study endeavors to investigate the roles and underlying mechanisms of miR-656-3p and Bone Morphogenetic Protein-2 (BMP-2) in DFH. It was recruited 94 patients with normal fracture healing (NFH) and 88 patients with DFH of the femoral neck. Serum miR-656-3p and BMP-2 expressions were quantified using RT-qPCR and the diagnostic potential of them for DFH was evaluated using ROC analysis. Factors influencing fracture healing were identified through logistic regression analysis. Osteogenic differentiation of MC3T3-E1 cells was induced, followed by evaluations of cell proliferation, apoptosis, and differentiation capabilities utilizing CCK-8, flow cytometry, and mRNA expression analysis of osteogenic markers. The targeting relationship between miR-656-3p and BMP-2 was validated through luciferase reporter assays. The levels of miR-656-3p were significantly elevated in DFH patients compared to those with NFH, whereas BMP-2 levels exhibited a decrease, a negative correlation between their expression patterns. Logistic regression analysis revealed that miR-656-3p and BMP-2 serve as influential factors in fracture healing, with their combined assessment exhibiting enhanced predictive value for DFH. Downregulation of miR-656-3p promoted proliferation and differentiation of MC3T3-E1 cells while inhibiting apoptosis. BMP-2, identified as a target of miR-656-3p, negated the effects of miR-656-3p downregulation when BMP-2 expression was inhibited. miR-656-3p modulates osteoblast function by targeting BMP-2, offering novel therapeutic and diagnostic targets for the management of DFH.

Functional Mechanism and Clinical Implications of lncRNA LINC-PINT in Delayed Fracture Healing

BACKGROUND

Fracture healing can be impeded or even compromised by various factors, resulting in a growing number of patients suffering. The lncRNA LINC-PINT has garnered attention for its latent role in enhancing fracture healing, but its specific functions in this process remain unclear.

OBJECTIVES

The primary objective of this study is to investigate the clinical relevance and underlying molecular mechanisms of LINC-PINT in delayed fracture healing (DFH), while also assessing its potential as an early diagnostic biomarker.

MATERIALS AND METHODS

The expression levels of LINC-PINT were measured in the serum of DFH patients and those with normal fracture healing using RT-qPCR. In MC3T3-E1 cells, the study investigated the influence on the expression of differentiation-related protein, cell viability, and apoptosis through the modulation of LINC-PINT and miR-324-3p. To elucidate the targeting relationship between LINC-PINT, miR-324-3p, and BMP2, a dual-luciferase reporter assay was employed.

RESULTS

The findings revealed a significant downregulation of LINC-PINT expression in DFH patients. LINC-PINT showed high sensitivity and specificity as a diagnostic marker for DFH. In MC3T3-E1 cells, LINC-PINT overexpression markedly enhanced the expression levels of ALP, OCN, Runx2, and OPN, improved cell viability, and inhibited apoptosis. LINC-PINT negatively regulated miR-324-3p, and the effects of LINC-PINT were counteracted by miR-324-3p. LINC-PINT was found to regulate BMP2 by targeting miR-324-3p.

CONCLUSION

LINC-PINT could serve as an early diagnostic biomarker for DFH and slow the progression of DFH by modulating BMP2 through the targeted regulation of miR-324-3p. This research presents new molecular targets for the diagnosis and treatment of DFH.

lncRNA CASC11 regulates the progress of delayed fracture healing via sponging miR-150-3p

BACKGROUND

Long non-coding RNA (lncRNA) plays a pivotal role in bone regeneration by interaction with microRNAs (miRNAs) and constructing a lncRNA-miRNA regulatory network.

OBJECTIVES

This research aimed to elucidate the role of lncRNA CASC11 in the delayed healing process of tibial fractures and to explore its potential regulatory mechanisms.

MATERIALS AND METHODS

The expression levels of CASC11 and miR-150-3p in serum samples were detected and the predictive capability of CASC11 regarding delayed healing in fracture patients. Furthermore, the study confirmed the accuracy of the binding sites between CASC11 and miR-150-3p. Subsequently, overexpression/interference plasmids of CASC11, along with overexpression plasmids co-transfected with both CASC11 and miR-150-3p, were systematically introduced into MC3T3-E1 cells to investigate their effects on the expression of osteogenic marker genes, as well as their influence on cellular proliferation and apoptosis.

RESULTS

The expression levels of CASC11 were significantly elevated, while miR-150-3p levels were markedly decreased in individuals exhibiting delayed fracture healing (P < 0.001). CASC11 was observed to suppress the expression of osteogenic marker genes, inhibit the proliferation of MC3T3-E1 cells, and promote cell apoptosis (P < 0.05). Furthermore, the overexpression of miR-150-3p effectively countered the inhibitory impact of CASC11 on osteogenic differentiation and the promoting effect on cell apoptosis (P < 0.05).

CONCLUSION

The sponging effect of CASC11 on miR-150-3p led to delayed fracture healing. CASC11 emerges as a potential target for treating delayed fracture healing.

Orthopedic revolution: The emerging role of nanotechnology

This review summarizes the latest progress in orthopedic nanotechnology, explores innovative applications of nanofibers in tendon repair, and evaluates the potential of selenium and cerium oxide nanoparticles in osteoarthritis and osteoblast differentiation. This review also describes the emerging applications of injectable hydrogels in cartilage engineering, emphasizing the critical role of interdisciplinary research and highlighting the challenges and future prospects of integrating nanotechnology into orthopedic clinical practice. This comprehensive approach provides a holistic perspective on the transformative impact of nanotechnology in orthopedics, offering valuable insights for future research and clinical applications.

The predictive value of stress-induced hyperglycemia parameters for delayed healing after tibial fracture post-surgery

PURPOSE

The objective of this retrospective cohort study was to investigate the predictive value of stress-induced hyperglycemia parameters for delayed healing after tibial fracture post-surgery.

METHODS

A cohort of 108 participants who underwent surgical intervention for tibial fractures caused by trauma was included in this retrospective study. Data collected from electronic medical records encompassed demographic characteristics, bone healing assessments, stress-induced hyperglycemia parameters, inflammatory markers, and stress-related hormones. Comparative analyses, correlation analyses, univariate logistic regression analyses, and receiver operating characteristic (ROC) curve analyses were conducted to assess the predictive value of the studied parameters.

RESULTS

The delayed healing group exhibited higher levels of fasting blood glucose, postprandial glucose, and HbA1c, as well as elevated levels of inflammatory markers and stress-related hormones compared to the normal healing group. Correlation analysis and logistic regression demonstrated positive associations between stress-induced hyperglycemia parameters, inflammatory markers, stress-related hormones, and delayed union of tibial fractures (R2: 0.183 ~ 0.403;OR: 1.091 ~ 16.332). ROC curve analysis revealed high area under the curve (AUC = 0.911) values for stress-induced hyperglycemia parameters, indicating their potential as predictive markers for delayed healing. Multivariate regression analysis further substantiated the predictive capability of stress-induced hyperglycemia parameters.

CONCLUSION

The study findings highlight the complex interplay between stress-induced hyperglycemia, inflammatory response, and bone healing outcomes in patients undergoing surgical intervention for tibial fractures. The identification of stress-induced hyperglycemia parameters as potential predictive markers for delayed healing after tibial fracture surgery offers insights for risk assessment and patient management, emphasizing the need for comprehensive understanding of these factors to optimize postoperative recovery in orthopedic patients.

Regulatory T cell-derived exosome mediated macrophages polarization for osteogenic differentiation in fracture repair

Refractory fracture presents an intractable challenge in trauma treatment. Selective polarization of macrophages as well as the recruitment of osteogenic precursor cells play key roles in osteogenic differentiation during fracture healing. Here we constructed regulatory T cell (Treg)-derived exosomes (Treg-Exo) for the treatment of fracture. The obtained exosomes displayed a spheroid shape with a hydrated particle size of approximately 130 nm. With further purification using CD39 and CD73 antibody-modified microfluidic chips, CD39 and CD73 specifically expressing exosomes were obtained. This kind of Treg-Exo utilized the ectonucleotidases of CD39 and CD73 to catalyze the high level of ATP in the fracture area into adenosine. The generated adenosine further promoted the selective polarization of macrophages. When interacting with mesenchymal stem cells (MSCs, osteogenic precursor cells), both Treg-Exo and Treg-Exo primed macrophages facilitated the proliferation and differentiation of MSCs. After administration in vivo, Treg-Exo effectively promoted fracture healing compared with conventional T cell-derived exosome. To further improve the delivery efficacy of exosomes and integrate multiple biological processes of fracture healing, an injectable hydrogel was fabricated to co-deliver Treg-Exo and stromal cell-derived factor 1 alpha (SDF-1α). With the dual effect of Treg-Exo for macrophage polarization and SDF-1α for MSC recruitment, the multifunctional hydrogel exerted a synergistic effect on fracture repair acceleration. This study provided a promising therapeutic candidate and synergistic strategy for the clinical treatment of fracture.

Macrophages-bone marrow mesenchymal stem cells crosstalk in bone healing

Bone healing is associated with many orthopedic conditions, including fractures and osteonecrosis, arthritis, metabolic bone disease, tumors and periprosthetic particle-associated osteolysis. How to effectively promote bone healing has become a keen topic for researchers. The role of macrophages and bone marrow mesenchymal stem cells (BMSCs) in bone healing has gradually come to light with the development of the concept of osteoimmunity. Their interaction regulates the balance between inflammation and regeneration, and when the inflammatory response is over-excited, attenuated, or disturbed, it results in the failure of bone healing. Therefore, an in-depth understanding of the function of macrophages and bone marrow mesenchymal stem cells in bone regeneration and the relationship between the two could provide new directions to promote bone healing. This paper reviews the role of macrophages and bone marrow mesenchymal stem cells in bone healing and the mechanism and significance of their interaction. Several new therapeutic ideas for regulating the inflammatory response in bone healing by targeting macrophages and bone marrow mesenchymal stem cells crosstalk are also discussed.