Role of coagulopathy in glucocorticoid-induced osteonecrosis of the femoral head

Human umbilical cord mesenchymal stem cells promote steroid-induced osteonecrosis of the femoral head repair by improving microvascular endothelial cell function

Recently, there has been growing interest in using cell therapy through core decompression (CD) to treat osteonecrosis of the femoral head (ONFH). Our study aimed to investigate the effectiveness and mechanism of human umbilical cord mesenchymal stem cells (hUCMSCs) in treating steroid-induced ONFH. We constructed a steroid-induced ONFH rabbit model as well as dexamethasone (Dex)-treated bone microvascular endothelial cells (BMECs) model of human femoral head. We injected hUCMSCs into the rabbit femoral head via CD. The effects of hUCMSCs on steroid-induced ONFH rabbit model and Dex-treated BMECs were evaluated via micro-CT, microangiography, histology, immunohistochemistry, wound healing, tube formation, and western blotting assay. Furthermore, we conducted single-cell RNA sequencing (scRNA-seq) to examine the characteristics of endothelial cells, the activation of signaling pathways, and inter-cellular communication in ONFH. Our data reveal that hUCMSCs improved the femoral head microstructure and bone repair and promoted angiogenesis in the steroid-induced ONFH rabbit model. Importantly, hUCMSCs improved the migration ability and angioplasty of Dex-treated BMECs by secreting COL6A2 to activate FAK/PI3K/AKT signaling pathway via integrin α1β1.

Research progress in the pathogenesis of hormone-induced femoral head necrosis based on microvessels: a systematic review

Hormonal necrosis of the femoral head is caused by long-term use of glucocorticoids and other causes of abnormal bone metabolism, lipid metabolism imbalance and blood microcirculation disorders in the femoral head, resulting in bone trabecular fracture, bone tissue necrosis collapse, and hip dysfunction. It is the most common type of non-traumatic necrosis of the femoral head, and its pathogenesis is complex, while impaired blood circulation is considered to be the key to its occurrence. There are a large number of microvessels in the femoral head, among which H-type vessels play a decisive role in the "angiogenesis and osteogenesis coupling", and thus have an important impact on the occurrence and development of femoral head necrosis. Glucocorticoids can cause blood flow injury of the femoral head mainly through coagulation dysfunction, endothelial dysfunction and impaired angiogenesis. Glucocorticoids may inhibit the formation of H-type vessels by reducing the expression of HIF-1α, PDGF-BB, VGEF and other factors, thus causing damage to the "angiogenesis-osteogenesis coupling" and reducing the ability of necrosis reconstruction and repair of the femoral head. Leads to the occurrence of hormonal femoral head necrosis. Therefore, this paper reviewed the progress in the study of the mechanism of hormone-induced femoral head necrosis based on microvascular blood flow at home and abroad, hoping to provide new ideas for the study of the mechanism of femoral head necrosis and provide references for clinical treatment of femoral head necrosis.

Analysis of the Potential Angiogenic Mechanisms of BuShenHuoXue Decoction against Osteonecrosis of the Femoral Head Based on Network Pharmacology and Experimental Validation

OBJECTIVE

Osteonecrosis of the femoral head (ONFH) is a common orthopedic disease with a high disability rate. The clinical effect of BuShenHuoXue decoction (BSHX) for ONFH is satisfactory. We aimed to elucidate the potential angiogenic mechanisms of BSHX in a rat femoral osteonecrosis model and bone marrow mesenchymal stem cells (BMSCs).

METHODS

With in vivo experiments, we established the steroid-induced osteonecrosis of the femoral head (SONFH) model using Sprague-Dawley (SD) rats (8-week-old). The rats were randomly divided into five group of 12 rats each and given the corresponding interventions: control, model (gavaged with 0.9% saline), BSHX low-, medium- and high-dose groups (0.132 3, 0.264 6, and 0.529 2 g/mL BSHX solution by gavage). After 12 weeks, haematoxylin and eosin (H&E) staining was preformed to evaluate rat osteonecrosis. the expression of angiogenic factors (CD31, VEGFA, KDR, VWF) in rat femoral head was detected by immunohistochemistry, qPCR and western blotting. In cell experiment, BMSCs were isolated and cultured in the femoral bone marrow cavity of 4-week-old SD rats. BMSCs were randomly divided into eight groups and intervened with different doses of BSHX-containing serum and glucocorticoids: control group (CG); BSHX low-, medium-, and high-dose groups (CG + 0.661 5, 1.323, and 2.646 g/kg BSHX gavage rat serum); dexamethasone (Dex) group; and Dex + BSHX low-, medium-, and high-dose groups (Dex + 0.661 5, 1.323, and 2.646 g/kg BSHX gavaged rat serum), the effects of BSHX-containing serum on the angiogenic capacity of BMSCs were examined by qPCR and Western blotting. A co-culture system of rat aortic endothelial cells (RAOECs) and BMSCs was then established. Migration and angiogenesis of RAOECs were observed using angiogenesis and transwell assay. Identification of potential targets of BSHX against ONFH was obtained using network pharmacology.

RESULTS

BSHX upregulated the expression of CD31, VEGFA, KDR, and VWF in rat femoral head samples and BMSCs (p < 0.05, vs. control group or model group). Different concentrations of BSHX-containing serum significantly ameliorated the inhibition of CD31, VEGFA, KDR and VWF expression by high concentrations of Dex. BSHX-containing serum-induced BMSCs promoted the migration and angiogenesis of RAOECs, reversed to some extent the adverse effect of Dex on microangiogenesis in RAOECs, and increased the number of microangiogenic vessels. Furthermore, we identified VEGFA, COL1A1, COL3A1, and SPP1 as important targets of BSHX against ONFH.

CONCLUSION

BSHX upregulated the expression of angiogenic factors in the femoral head tissue of ONFH model rats and promoted the angiogenic capacity of rat RAOECs and BMSCs. This study provides an important basis for the use of BSHX for ONFH prevention and treatment.

X-ray, digital tomographic fusion, CT, and MRI in early ischemic necrosis of the femoral head

To investigate the imaging performance of radiography, digital tomographic fusion (DTS), computed tomography (CT), and magnetic resonance imaging (MRI) in the diagnosis of early avascular necrosis of the femoral head (ANFH). A total of 220 patients with ANFH who visited our hospital from January 2020 to January 2022 were included in the study. X-ray, DTS, CT, and MRI examinations of both hips were performed for all patients. The trabecular structure, bone density changes, femoral head morphology, and joint space changes were observed using the aforementioned imaging modalities. The staging was performed according to the Association Research Circulation Osseous (ARCO) criteria. The diagnostic detection rate of each imaging modality, and the sensitivity, specificity, positive predictive value, and negative predictive value of each examination for diagnosing early ANFH were calculated and compared. Patients were diagnosed with stage I (n = 65), stage II (n = 85), stage III (n = 32), and stage IV (n = 38) ANFH. For MRI, the detection rate (97.7%), sensitivity (94.7%), specificity (88.6%), positive predictive value (95.9%), and negative predictive value (92.5%), for diagnosing early ANFH, were significantly higher than those of other imaging methods (P < .05). MRI is the most accurate and sensitive imaging method for diagnosing early ANFH and has important clinical applications.

Did the COVID-19 Pandemic Coincide With an Increase in Osteonecrosis as Indication for Total Hip Arthroplasty in Older Patients?

BACKGROUND

Osteonecrosis of the femoral head is a common indication for total hip arthroplasty (THA). It is unclear to what extent the COVID-19 pandemic has impacted its incidence. Theoretically, the combination of microvascular thromboses and corticosteroid use in patients who have COVID-19 may increase the risk of osteonecrosis. We aimed to (1) assess recent osteonecrosis trends and (2) investigate if a history of COVID-19 diagnosis is associated with osteonecrosis.

METHODS

This retrospective cohort study utilized a large national database between 2016 and 2021. Osteonecrosis incidence in 2016 to 2019 was compared to 2020 to 2021. Secondly, utilizing a cohort from April 2020 through December 2021, we investigated whether a prior COVID-19 diagnosis was associated with osteonecrosis. For both comparisons, Chi-square tests were applied.

RESULTS

Among 1,127,796 THAs performed between 2016 and 2021, we found an osteonecrosis incidence of 1.6% (n = 5,812) in 2020 to 2021 compared to 1.4% (n = 10,974) in 2016 to 2019; P < .0001. Furthermore, using April 2020 to December 2021 data from 248,183 THAs, we found that osteonecrosis was more common among those who had a history of COVID-19 (3.9%; 130 of 3,313) compared to patients who had no COVID-19 history (3.0%; 7,266 of 244,870); P = .001).

CONCLUSION

Osteonecrosis incidence was higher in 2020 to 2021 compared to previous years and a previous COVID-19 diagnosis was associated with a greater likelihood of osteonecrosis. These findings suggest a role of the COVID-19 pandemic on an increased osteonecrosis incidence. Continued monitoring is necessary to fully understand the impact of the COVID-19 pandemic on THA care and outcomes.

Network pharmacology-based and molecular docking-based analysis of You-Gui-Yin for the treatment of osteonecrosis of the femoral head

You-Gui-Yin (YGY) is a classic prescription for warming up kidney-Yang and filling in kidney essence in traditional Chinese medicine, and has been used to treat osteonecrosis of the femoral head (ONFH) effectively. However, the underlying mechanisms are still unknown. This study is aimed at exploring the possible mechanisms of action of the YGY in the treatment of ONFH based on network pharmacology and molecular docking. TCMSP was used to screen the active components and targets of YGY. The disease targets of ONFH were collected in several public databases. The protein-protein interaction (PPI) Network was constructed using the STRING platform. The Metascape database platform was used for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The key active components and core target proteins of YGY in the treatment of ONFH were verified by the molecular docking. 120 active components were obtained from YGY, among which 73 components were hit by the 117 drug-disease intersection targets. Key effective components included quercetin, kaempferol, beta-sitosterol, glycitein, beta-carotene, and so on. Core target proteins included ALB, AKT1, TNF, IL6, TP53, and so on. According to GO and KEGG analyses, there were 1762 biological processes, 94 cellular component, 138 molecular function and 187 signaling pathways involved. we selected the top 20 biological processes (BP), cellular components (CC), molecular functions (MF) and signaling pathways to draw the heat maps, showing that Lipid and atherosclerosis signaling pathway, IL-17 signaling pathway, HIF-1 signaling pathway, relaxin signaling pathway and MAPK signaling pathway and other pathways may play a key role in the treatment of ONFH by YGY. The results of molecular docking showed that key effective components and corresponding core target proteins exhibited the good binding activity. YGY can treat ONFH through multicomponents, multitargets, and multipathways, which provides a reference for the subsequent research, development of targeted drugs and clinical application.

Laboratory indices in patients with osteonecrosis of the femoral head: a retrospective comparative study

BACKGROUND

Osteonecrosis of the femoral head is a degenerative condition linked to corticosteroids, alcoholism, or trauma. With its rising prevalence due to increased hormone drug use and its debilitating effects on young to middle-aged individuals, understanding its association with specific laboratory indicators can aid early diagnosis and prevention.

METHODS

Upon retrospective analysis of the clinical data pertaining to individuals diagnosed with femoral head necrosis, spanning from January 2016 to January 2022, a comprehensive evaluation was conducted within the same time frame. The study aimed to ascertain the presence of femoral head necrosis in a total of 1176 individuals. A total of 1036 healthy patients were recruited randomly, ensuring that their ages matched. The risk variables associated with the utilization of logistic regression analysis and analysis techniques are employed. The patient examines the age distribution within a specific age group.

RESULTS

The levels of high-density lipoprotein, low-density lipoprotein A1, lipoprotein B1, total protein, albumin, globulin, and other lipophilic metabolism and coagulation markers exhibited a statistically significant increase compared to the control group. A multifactor logistic regression analysis was conducted to identify potential risk factors associated with femoral head necrosis in patients.

CONCLUSION

Femoral head necrosis is associated with a range of variables including coagulation malfunction, lipid metabolic abnormalities, and inflammation.

A Molecular Troika of Angiogenesis, Coagulopathy and Endothelial Dysfunction in the Pathology of Avascular Necrosis of Femoral Head: A Comprehensive Review

Avascular necrosis of the femoral head (ANFH) is a painful disorder characterized by the cessation of blood supply to the femoral head, leading to its death and subsequent joint collapse. Influenced by several risk factors, including corticosteroid use, excessive alcohol intake, hypercholesterolemia, smoking and some inflammatory disorders, along with cancer, its clinical consequences are thrombus formation due to underlying inflammation and endothelial dysfunction, which collaborates with coagulopathy and impaired angiogenesis. Nonetheless, angiogenesis resolves the obstructed free flow of the blood by providing alternative routes. Clinical manifestations of early stage of ANFH mimic cysts or lesions in subchondral bone, vasculitis and transient osteoporosis of the hip, rendering it difficult to diagnose, complex to understand and complicated to cure. To date, the treatment methods for ANFH are controversial as no foolproof curative strategy is available, and these depend upon different severity levels of the ANFH. From an in-depth understanding of the pathological determinants of ANFH, it is clear that impaired angiogenesis, coagulopathy and endothelial dysfunction contribute significantly. The present review has set two aims, firstly to examine the role and relevance of this molecular triad (impaired angiogenesis, coagulopathy and endothelial dysfunction) in ANFH pathology and secondly to propose some putative therapeutic strategies, delineating the fact that, for the better management of ANFH, a combined strategy to curtail this molecular triangle must be composed rather than focusing on individual contributions.

FAR591 promotes the pathogenesis and progression of SONFH by regulating Fos expression to mediate the apoptosis of bone microvascular endothelial cells

The specific pathogenesis of steroid-induced osteonecrosis of the femoral head (SONFH) is still not fully understood, and there is currently no effective early cure. Understanding the role and mechanism of long noncoding RNAs (lncRNAs) in the pathogenesis of SONFH will help reveal the pathogenesis of SONFH and provide new targets for its early prevention and treatment. In this study, we first confirmed that glucocorticoid (GC)-induced apoptosis of bone microvascular endothelial cells (BMECs) is a pre-event in the pathogenesis and progression of SONFH. Then, we identified a new lncRNA in BMECs via lncRNA/mRNA microarray, termed Fos-associated lincRNA ENSRNOT00000088059.1 (FAR591). FAR591 is highly expressed during GC-induced BMEC apoptosis and femoral head necrosis. Knockout of FAR591 effectively blocked the GC-induced apoptosis of BMECs, which then alleviated the damage of GCs to the femoral head microcirculation and inhibited the pathogenesis and progression of SONFH. In contrast, overexpression of FAR591 significantly promoted the GC-induced apoptosis of BMECs, which then aggravated the damage of GCs to the femoral head microcirculation and promoted the pathogenesis and progression of SONFH. Mechanistically, GCs activate the glucocorticoid receptor, which translocates to the nucleus and directly acts on the FAR591 gene promoter to induce FAR591 gene overexpression. Subsequently, FAR591 binds to the Fos gene promoter (-245∼-51) to form a stable RNA:DNA triplet structure and then recruits TATA-box binding protein associated factor 15 and RNA polymerase II to promote Fos expression through transcriptional activation. Fos activates the mitochondrial apoptotic pathway by regulating the expression of Bcl-2 interacting mediator of cell death (Bim) and P53 upregulated modulator of apoptosis (Puma) to mediate GC-induced apoptosis of BMECs, which leads to femoral head microcirculation dysfunction and femoral head necrosis. In conclusion, these results confirm the mechanistic link between lncRNAs and the pathogenesis of SONFH, which helps reveal the pathogenesis of SONFH and provides a new target for the early prevention and treatment of SONFH.

Lnc Tmem235 promotes repair of early steroid-induced osteonecrosis of the femoral head by inhibiting hypoxia-induced apoptosis of BMSCs

Bone marrow mesenchymal stem cells (BMSCs) have been used in the treatment of early steroid-induced osteonecrosis of the femoral head (SONFH). However, the hypoxic microenvironment in the osteonecrotic area leads to hypoxia-induced apoptosis of transplanted BMSCs, which limits their efficacy. Therefore, approaches that inhibit hypoxia-induced apoptosis of BMSCs are promising for augmenting the efficacy of BMSC transplantation. Our present study found that under hypoxia, the expression of the long noncoding RNA (Lnc) transmembrane protein 235 (Tmem235) was downregulated, the expression of Bcl-2-associated X protein was upregulated, the expression of B-cell lymphoma-2 protein was downregulated, and the apoptotic rate of BMSCs was over 70%. However, overexpression of Lnc Tmem235 reversed hypoxia-induced apoptosis of BMSCs and promoted their survival. These results demonstrated that Lnc Tmem235 effectively inhibited hypoxia-induced apoptosis of BMSCs. Mechanistically, we found that Lnc Tmem235 exhibited competitive binding to miR-34a-3p compared with BIRC5 mRNA, which is an inhibitor of apoptosis; this competitive binding relieved the silencing effect of miR-34a-3p on BIRC5 mRNA to ultimately inhibit hypoxia-induced apoptosis of BMSCs by promoting the expression of BIRC5. Furthermore, we cocultured BMSCs overexpressing Lnc Tmem235 with xenogeneic antigen-extracted cancellous bone to construct tissue-engineered bone to repair a model of early SONFH in vivo. The results showed that overexpression of Lnc Tmem235 effectively reduced apoptosis of BMSCs in the hypoxic microenvironment of osteonecrosis and improved the effect of BMSC transplantation. Taken together, our findings show that Lnc Tmem235 inhibited hypoxia-induced apoptosis of BMSCs by regulating the miR-34a-3p/BIRC5 axis, thus improving the transplantation efficacy of BMSCs for treating early SONFH.

Ginkgo biloba L. extract prevents steroid-induced necrosis of the femoral head by rescuing apoptosis and dysfunction in vascular endothelial cells via the PI3K/AKT/eNOS pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Ginkgo biloba L. extract (EGb) is one of the world's most extensively used herbal medicines. Due to the diverse pharmacological properties of EGb, it has been used in the treatment of neurological illnesses, as well as cardiovascular and cerebrovascular ailments. However, the effect and pharmacological mechanism of EGb on steroid-induced necrosis of the femoral head (SINFH) are still unclear.

AIM OF THE STUDY

SINFH remains a challenging problem in orthopedics. Previous investigations have shown that EGb has the potential to reduce the occurrence of SINFH. The goal was to determine the effect and mechanism of EGb in preventing SINFH by inhibiting apoptosis and improving vascular endothelial cells (VECs) functions.

MATERIALS AND METHODS

CCK-8, nitric oxide (NO) production and flow cytometry were used to determine the cell apoptosis and function. The scratch and angiogenesis tests assessed migration and tube formation. Western blot analysis detected the expressions of apoptosis-related proteins and PI3K/AKT/eNOS pathway-related proteins. Apoptosis and angiogenesis were also detected treated with the inhibitors. A mouse model of SINFH was established. Paraffin section was used to determine the necrotic pathology and apoptosis. Vessels in the femoral heads were assessed by immunofluorescence staining.

RESULTS

When stimulated by methylprednisolone (MPS), cell viability, NO generation and tube formation were decreased, the apoptotic rate increased. Simultaneously, MPS decreased the expression levels of p-PI3K, p-AKT, and p-eNOS. EGb increased the expression levels of these proteins, restrained apoptosis, and restored cell functions. The addition of the inhibitors decreased anti-apoptotic effect and angiogenesis. In addition, when compared to the model mice, there were fewer empty lacunae and normal trabecular arrangement after taking different doses of EGb. The protective effect was also confirmed by the vascular quantitative analysis in vivo.

CONCLUSION

This study established that EGb increased endothelial cell activity and inhibited apoptosis and function loss induced by MPS, elucidating the effect and molecular mechanism of EGb on early SINFH.

Tongue Manifestation in Patients with Osteonecrosis of the Femoral Head: A Cross-sectional Study

OBJECTIVE

Although tongue manifestation is a vital component of Traditional Chinese Medicine (TCM), relevant research on patients with osteonecrosis of the femoral head (ONFH) is still lacking. This study will explore the characteristic tongue manifestation of ONFH patients to inform future research and clinical practice.

METHODS

This is a cross-sectional study. All ONFH patients meeting criteria and their clinical data were collected from the online China osteonecrosis of the femoral head database (CONFHD) since it was created. Organized tongue manifestations of eligible patients through the tongue manifestation acquisition instrument, including tongue shape, tongue color, tongue coating thickness, tongue coating color and tongue coating moisture. We used descriptive analysis for the general information while systematic clustering analysis for the better summary of tongue characteristics.

RESULTS

A total of 375 ONFH patients were included with an average age of 46.3 years. Most patients appeared with enlarged tongue body (54.4%), and the proportions of pale and red tongue (62.4%) were higher than others. Tongue coating were mainly showed as thick (64.5%), white (57.6%) and moist (79.7%). Comparison of tongue shape between different causes of ONFH had a significant statistically difference (P = 0.000). Tongue manifestations could be cluster analyzed into three categories which were matched into four TCM syndromes.

CONCLUSIONS

The tongue manifestation of ONFH patients has a significant change both in tongue body and coating, and different features may be related to the ONFH pathology. This study provides new and valuable tongue informations for a preliminary screening of ONFH patients.

Vitamin B2 Prevents Glucocorticoid-Caused Damage of Blood Vessels in Osteonecrosis of the Femoral Head

Osteonecrosis of the femoral head (ONFH) is a disorder that can cause collapse of the femoral head. The damage and dysfunction of femoral head microvascular endothelial cells are related to the pathogenesis of glucocorticoid-induced ONFH. Reports suggest that vitamin B₂ can promote osteoblast differentiation and prevent low bone mineral density and prevent reperfusion oxidative injury. To explore the effect and possible molecular mechanism of vitamin B₂ on the ONFH and Human Umbilical Vein Endothelial Cells (HUVECs), we performed a rat model of ONFH by dexamethasone. The rats were randomly divided into four groups: control group, vitamin B₂ group, dexamethasone group, and dexamethasone combined with vitamin B₂ treatment group. HUVECs were used to further prove the role and mechanism of vitamin B₂ in vitro. In patients, according to immunohistochemical and qRT-PCR of the femoral head, the angiogenic capacity of the ONFH femoral head is compromised. In vivo, it showed that vitamin B₂ could inhibit glucocorticoid-induced ONFH-like changes in rats by suppressing cell apoptosis, promoting the regeneration of blood vessels, and increasing bone mass. According to in vitro results, vitamin B₂ could induce the migration of HUVECs, enhance the expression of angiogenesis-related factors, and inhibit glucocorticoid-induced apoptosis. The underlying mechanism may be that vitamin B₂ activates the PI3K signaling pathway. Vitamin B₂ alleviated dexamethasone-induced ONFH, and vitamin B₂ could promote the proliferation and migration of HUVECs and inhibit their apoptosis by activating the PI3K/Akt signaling pathway. Vitamin B₂ may be a potentially effective treatment for ONFH.

Anti-RNP Antibody: A Potential Novel Predictor for Osteonecrosis in Systemic Lupus Erythematosus

Objective

To explore risk factors for developing osteonecrosis in patients with systemic lupus erythematosus (SLE).

Methods

Twenty-six SLE patients with osteonecrosis from January 2018 to December 2019 were described. Fifty SLE patients without osteonecrosis were selected as controls from the SLE database (total 2,680) of our hospital during the same period. Clinical manifestations and laboratory tests were recorded and analyzed, especially antibodies. Univariate and multivariate analyses were used to evaluate possible associated risk factors.

Results

Twenty-six (3 male, 23 female) SLE patients with osteonecrosis were confirmed by X-ray and magnetic resonance imaging. The median course from SLE onset to osteonecrosis onset was 45 (range 2–302) months. Seven (27%) patients had a single joint involved and 19 (73%) patients had two or more joints involved. Besides, the incidence of femoral head osteonecrosis (FHON), knee ON, and humerus head ON were 85% (22/26), 27% (7/26), and 12%(3/26), respectively. The multivariate logistic regression analysis showed that the score of European Consensus Lupus Activity Measurement (ECLAM) at SLE onset [odds ratio (OR) 1.37; 95% confidence interval (CI) 1.07–1.75], a cumulative dose of prednisone above 10 g (OR 15.49; 95% CI 3.38–84.61), and positive of independent anti-RNP antibodies (OR 3.35; 95% CI 0.80–10.73) were significantly associated with osteonecrosis in SLE.

Conclusion

The score of ECLAM at SLE onset, a cumulative dose of prednisone above 10 g, and positive anti-RNP antibodies are associated with osteonecrosis in SLE. Herein, we reported for the first time that anti-RNP antibodies were associated with osteonecrosis in SLE patients and might be a novel predictor.

Plasma lipidomics analysis reveals altered lipids signature in patients with osteonecrosis of the femoral head

INTRODUCTION

Although studies have established a link between lipid metabolism disorder and osteonecrosis of the femoral head (ONFH), the characteristics of the circulating lipidome signature of ONFH have not yet been investigated and need to be explored.

OBJECTIVES

We aimed to explore the plasma lipidome signatures in patients with ONFH, and to identify specific lipid biomarkers of ONFH.

METHODS

In this study, a comprehensive detection and analysis of plasma lipidomics was conducted in clinical human cohort, including 32 healthy normal control (NC) subjects and 91 ONFH patients in different subgroups [alcohol-induced ONFH (AONFH), steroid-induced ONFH (SONFH), and traumatic-induced ONFH (TONFH)] or at different disease stages (stage I, II, III and IV of ONFH) using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS).

RESULTS

Overall, the plasma lipidome profile differs between ONFH and NC samples. Lipidome signature including 22 common differentially expressed lipids (DELs) in all three subgroups (variable importance in projection > 1, P < 0.05, fold change > 1.5 or < 0.67, compared to the NC group) was identified. Besides, the subtype-specific lipidome profiles for each ONFH subgroup were also analyzed. Generally, the AONFH subgroup has the largest number of DELs, and the plasma levels of triacylglycerol lipid compounds increased obviously in the AONFH samples. In the subgroup of SONFH, the relative abundance of lipid 4-Aminobenzoic acid increased significantly with changes in the expression of several of its interactive genes. We have identified that 9 stage-positive and 2 stage-negative lipids may function as novel biomarkers predicting the progression of ONFH.

CONCLUSION

Our study presents an overview of the phenotype-related plasma lipidome signature of patients with ONFH. The results will provide insight into the mechanisms underlying the metabolism of lipids in the pathogenesis and progression of ONFH and help identify novel lipids biomarkers or disease diagnosis and treatment targets.

Global research trends of steroid-induced osteonecrosis of the femoral head: A 30-year bibliometric analysis

OBJECTIVE

To explore the global research trends and hotspots of steroid-induced osteonecrosis of the femoral head (SONFH) through qualitative and quantitative analysis of bibliometrics.

METHODS

All publications on SONFH published from 1992 to 2021 were extracted from the Web of Science Core Collection database. CiteSpace was used for the visualization analysis of major countries, active institutions, productive authors, and the burst of keywords. VOSviewer was used for coupling analysis of countries/regions, institutions, and authors. Microsoft Excel 2017 was used for statistical analysis, drawing bar charts, pie charts, and cumulative area charts. The software of MapInfo was used to draw the distribution map of the publications.

RESULTS

A total of 780 publications were included for analyses. The most productive year was 2020 with 98 records. China was the most influential country with 494 publications, an H-index of 59, and total citations of 16820. The most prolific institution was Shanghai Jiaotong University in China with 53 publications and 998 citations. Clinical Orthopaedics and Related Research (IF = 4.755, 2021) was the most active journal with 26 articles. The hot keywords were "osteonecrosis", "avascular necrosis", "osteogenic differentiation", "proliferation", "PPAR gamma", "apoptosis", "oxidative stress", "genetic polymorphism" and "mesenchymal stem cells". The keywords like "proliferation", "PPAR gamma" and "genome-wide" have emerged in recent years.

CONCLUSION

The number of publications in SONFH has increased significantly in the last three decades. The pathologic mechanism of SONFH gathered most research interests. Genomics and cell molecular biology of SONFH are the research frontiers.

Steroid-Induced Osteonecrosis of the Femoral Head: Novel Insight Into the Roles of Bone Endothelial Cells in Pathogenesis and Treatment

Steroid-induced osteonecrosis of the femoral head (SONFH) is a disease characterized by the collapse of the femoral head. SONFH occurs due to the overuse of glucocorticoids (GCs) in patients with immune-related diseases. Among various pathogenesis proposed, the mechanism related to impaired blood vessels is gradually becoming the most convincing hypothesis. Bone endothelial cells including bone microvascular endothelial cells (BMECs) and endothelial progenitor cells (EPCs) play a crucial role in the maintenance of vascular homeostasis. Therefore, bone endothelial cells are key regulators in the occurrence and progression of SONFH. Impaired angiogenesis, abnormal apoptosis, thrombosis and fat embolism caused by the dysfunctions of bone endothelial cells are considered to be the pathogenesis of SONFH. In addition, even with high disability rates, SONFH lacks effective therapeutic approach. Icariin (ICA, a flavonoid extracted from Epimedii Herba), pravastatin, and VO-OHpic (a potent inhibitor of PTEN) are candidate reagents to prevent and treat SONFH through improving above pathological processes. However, these reagents are still in the preclinical stage and will not be widely used temporarily. In this case, bone tissue engineering represented by co-transplantation of bone endothelial cells and bone marrow mesenchymal stem cells (BMSCs) may be another feasible therapeutic strategy.

Comprehensive analysis of pivotal biomarkers, immune cell infiltration and therapeutic drugs for steroid-induced osteonecrosis of the femoral head

Steroid-induced osteonecrosis of the femoral head (SONFH) is a progressive disease that leads to an increased disability rate. This study aimed to ascertain biomarkers, infiltrating immune cells, and therapeutic drugs for SONFH. The gene expression profile of the GSE123568 dataset was downloaded from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were identified using the NetworkAnalyst platform. Functional enrichment, protein-protein interaction network (PPI), and module analyses were performed using Metascape tools. An immune cell abundance identifier was used to explore immune cell infiltration. Furthermore, hub genes were identified based on maximal clique centrality (MCC) evaluation using cytoHubba application and confirmed by qRT-PCR using clinical samples. Finally, the L1000 platform was used to determine potential drugs for SONFH treatment. The SONFH mouse model was used to determine the therapeutic effects of aspirin. In total, 429 DEGs were identified in SONFH samples. Functional enrichment analysis showed that these DEGs were enriched in myeloid leukocyte activation and osteoclast differentiation processes. A set of nine immune cell types was confirmed to be markedly different between the SONFH and control samples. All 10 hub genes were significantly highly expressed in the serum of SONFH patients, as shown by qRT-PCR. Finally, the therapeutic effect of aspirin on SONFH was examined in animal experiments. Taken together, our data revealed the hub genes and infiltrating immune cells in SONFH, and we also screened potential drugs for use in SONFH treatment.

IKKe in osteoclast inhibits the progression of methylprednisolone-induced osteonecrosis

Previous studies have described that NF-κB signaling mediated by NFκB-inducing kinase (NIK) plays a critical role of the differentiation of osteoclasts. We aim to explore the role of IKKe in methylprednisolone -induced osteonecrosis of the femoral head (ONFH). Methylprednisolone-induced ONFH mice model was successfully established, and subjected to micro computed tomography to detect the femoral head image of the mice. Bone marrow cells from experimental mice were collected and cultured. qPCR and immunoblot were performed to examine the possible signal pathways of IKKe involvement, and osteoclast-related gene expressions in IKKe+/+ and IKKe-/- cells in vitro and in vivo were examined. It was found that the levels of IKKe decreased in ONFH patients, and IKKe interacted with NIK in the NF-κB signal pathway to suppress osteoclasts via inhibiting the transcription of NIK. Furthermore, IKKe knockout promoted the osteoclastogenesis in mice model. Finally, IKKe knockout suppressed methylprednisolone-induced ONFH and pro-inflammatory responses in mice model. Our findings show a mechanism of IKKe inhibition of the progression of methylprednisolone-induced ONFH via the NIK/NF-κB pathway.

Associations between glucocorticoids, antiphospholipid antibodies and femur head necrosis in patients with SLE: a directed acyclic graph-based multicentre study

Background

Osteonecrosis of the femoral head (ONFH) remains a major cause of disability in patients with systemic lupus erythematosus (SLE) and seriously impairs quality of life. This study aimed to investigate associations between glucocorticoids (GCs), antiphospholipid antibodies (aPLs), and ONFH in patients with SLE.

Methods

We conducted a multicentre cohort study on patients with SLE and used a directed acyclic graph-based analysis strategy. Details of GC therapy, aPLs status, other drug administration and other SLE-related characteristics were collected. ONFH occurrence during follow-up was determined by magnetic resonance imaging. Multivariable logistic regression and generalized estimating equation models were performed to assess their effects on ONFH, and a simplified scoring system comprising these factors for short- and medium-term SLE-ONFH prediction was developed by receiver operating characteristic curve analysis.

Results

Of 449 SLE patients with a median follow-up duration of 5.3 years, 41 (9.1%) developed ONFH. Independently risk factors of SLE-ONFH including: average daily GC dose with an adjusted odds ratio (aOR) of 1.1 and 95% confidence interval (CI) of 1.0-1.1; GC therapy duration (3-5 years: aOR 3.3, 95% CI 1.4-7.8; >5 years: aOR 8.0, 95% CI 3.3-19.4); initial intravenous GC (aOR 4.4, 95% CI 1.9-10.1); positive aPLs (aOR 2.8, 95% CI 1.4-5.8); and Arterial hypertension secondary to GC usage (aOR 5.2, 95% CI 1.4-19.1). And we successfully developed the simplified scoring system (SCORE model) with an area under the curve of 0.88 (95% CI 0.82-0.94).

Conclusion

Based on the risk factors involved in the development of SLE-ONFH, a novel SCORE model was developed, which might be helpful for risk stratification of SLE-ONFH in clinical practice.

Alterations in the Retinal Vascular Network and Structure in Myelin Oligodendrocyte Glycoprotein Antibody-Associated Optic Neuritis: A Longitudinal OCTA Study

Purpose: To investigate the longitudinal microstructural and microvascular changes in patients with myelin oligodendrocyte glycoprotein antibody-associated optic neuritis (MOG-ON) without new attacks.Methods: We included 20 eyes of 12 MOG-ON patients without new attacks during the follow-up and 24 eyes of 12 age- and sex-matched healthy controls.Results: The BCVA, retinal vessels and structure were significantly lower in MOG-ON eyes than in healthy eyes(all P < .05). In MOG-ON eyes, the BCVA (p = .408) and mean deviation (p = .854) were not significantly decreased at the follow-up visit. However, there were small, significant decreases in parafoveal vessel density (p = .026), peripapillary vessel density (p = .008), and RNFL thickness (p = .03), but not GCIPL thickness (p = .107).Conclusions: Ongoing deterioration was observed in RNFL thickness and parafoveal and peripapillary vessel density, but not GCIPL thinning, in MOG-ON eyes without a new attack of ON.

CircCDR1as Suppresses Bone Microvascular Endothelial Cell Activity and Angiogenesis Through Targeting miR-135b/ FIH-1 Axis

Objective

The current study investigated the role of CircCDR1as on angiogenesis of bone microvascular endothelial cells (BMECs) isolated from non‐traumatic ONFH.

Methods

Forty corticosteroid‐induced ONFH patients received THA were enrolled in our study. Expressions of CircCDR1as, miR‐135b, and FIH‐1 were detected by qRT‐PCR in affected necrosis tissue and non‐affected normal tissue. Bone microvascular endothelial cells (BMEC) were isolated from six patients and treated with 0.1 mg/mL hydrocortisone to establish a GC‐damaged model of BMECs. Circ CDR1as plasmid and miR‐135b mimic were transfected into BMECs. BMEC proliferation was assessed using MTT assays. The migration ability of cells was detected by scratch‐wound assays. Matrigel assay was performed to detect angiogenesis in vitro. Western blot assay was used to detect HIF‐1α, VEGF, and FIH‐1 expressions. FISH, RNA pull down, RIP, and luciferase assay were carried out to determine the interaction of CircCDR1as, miR‐135b, and FIH‐1.

Results

CircCDR1as was upregulated(2.02 ± 0.30 vs. 1.00 ± 0.10,P < 0.001) whereas miR‐135b was downregulated (0.55 ± 0.12 vs. 1.00 ± 0.10,P < 0.001) in affected tissues than in non‐affected tissues. Expression of CircCDR1as and FIH‐1 were negatively associated with miR‐135b in affected tissues (CircCDR1as with miR‐135b: r = −0.506, P < 0.001; FIH‐1 with miR‐135b r = −0.510, P < 0.001). Total blood tubule density was increased when CircCDR1as was silenced compared with NC (P < 0.01 vs. NC). The number of migrated BMECs were significantly increased in CircCDR1as silencing group compared with NC group (P < 0.05 vs. NC). In addition, CircCDR1as plasmids transfection increased the protein expressions of FIH‐1 (P < 0.05 vs. NC) and reduced the HIF‐1α as well as VEGF expression compared with NC group (P < 0.05 vs. NC). FISH, RNA pull down, RIP, and luciferase assay identified that FIH‐1 was a target of miR‐135b and could be modulated by CircCDR1as.

Conclusion

CircCDR1as decreases angiogenesis and proliferation of BMECs by sponging miR‐135b and upregulate FIH‐1.

Novel MRI technique for the quantification of biochemical deterioration in steroid-induced osteonecrosis of femoral head: a prospective diagnostic trial

To explore the novel magnetic resonance imaging techniques, IVIM-DWI and IDEAL-IQ in detecting bone marrow fat and microcirculation in steroid-induced osteonecrosis of the femoral head (SIONFH). In this prospective study, 49 patients (80 hips) with SIONFH taking glucocorticoids and 24 healthy volunteers (48 hips) were recruited and assessed by T1WI, T2WI/fs, IDEAL-IQ and IVIM-DWI. The affected hips, contralateral asymptomatic hips and normal hips, as well as normal, penumbra and necrotic areas in the affected hips, were classified and evaluated. Imaging results were compared with histologic bone sections obtained from SIONFH patients undergoing surgery. The fat fraction (FF) and perfusion fraction (f) differences between groups were analyzed using analysis of variance, the LSD t-test, Pearson correlation analysis and ROC curve analysis. Our results demonstrate that IDEAL-IQ (FF) and IVIM-DWI (f) enable the classification of SIONFH at different ARCO stages. The FF was positively associated with the progression of the disease (r = 0.72), in contrast to f (r = -0.17). The FF and f were significantly different among the necrotic, penumbra and normal areas, and they were negatively correlated with each other (r = -0.37). The diagnostic sensitivity and specificity of IDEAL-IQ were 96.9% and 86.7%, and those of IVIM-DWI were 72.34% and 58.33%, respectively. The FF in contralateral asymptomatic hips was significantly higher than in normal hips, but no difference was found for f. IDEAL-IQ, and not IVIM-DWI, was identified to successfully detect bone marrow fat, which is beneficial to the diagnosis of the severity of SIONFH.

Sox11 Modified Tendon-Derived Stem Cells Promote the Repair of Osteonecrosis of Femoral Head

Osteonecrosis of the femoral head (ONFH) is a leading cause of mobility impairment which may lead to a total hip replacement. Recent studies have found tendon derived stem cells (TDSCs) might be an ideal cell source for musculoskeletal tissue regeneration. And our previous study has shown Sox11 could promote osteogenesis of bone marrow-derived MSCs. However, the effect of TDSCs or Sox11 over-expressing TDSCs (TDSCs-Sox11) on bone regeneration in ONFH has not been investigated. In the present study, TDSCs were infected with AAV carrying Sox11 or empty vector. We showed that Sox11 could promote the proliferation and osteogenic differentiation of TDSCs, as well as angiogenesis in vitro. The western blot analysis showed that Sox11 could activate the PI3K/Akt signaling pathway to promote osteogenesis of TDSCs. Finally, using a rabbit model of hormone-induced ONFH, our result demonstrated that local administration of TDSCs or TDSCs overexpressing Sox11 could accelerate bone regeneration in necrotic femoral heads, and TDSCs overexpressing Sox11 showed better effects. TDSCs over-expressing Sox11 might be a promising cell source for stem cell therapy to promote bone regeneration, such as ONFH, fracture, bone defect, and so on.

An MSC bone-homing compound, Rab001, increases bone mass and reduces the incidence of osteonecrosis in a glucocorticoid-induced osteonecrosis mouse model

Currently, there are no effective medications to either prevent or slow the progression of atraumatic osteonecrosis (ON). The objective of this study is to determine the effects of bone-targeted delivery of mesenchymal stem cells on the prevalence of ON in a glucocorticoid (GC)-induced mouse model. Eight-week-old male BALB/c mice were randomized into groups that received placebo (PL), prednisolone (GC), or concurrent treatments with GC + mesenchymal stromal cells (MSCs), Rab001 or GC + Rab001 + MSCs. Human parathyroid hormone (hPTH) was used as a positive control for bone anabolism. Mice were killed after 30 days, and quantitative measurements of bone mass, bone strength, prevalent ON at the distal femoral epiphysis (DFE) were performed. Angiogenesis was accessed by RNA-Seq, the circulating angiogenic markers, as well as by immunohistochemical staining. We have showed that a novel agent, Rab001 that can noncovalently bind to mesenchymal stem cells (MSC) and direct them to the bone, prevents the incidence of glucocorticoid-induced osteonecrosis in the mouse. In contrast, PTH, a bone anabolic treatment, preserves bone mass but sustains higher ON incidence than Rab001+/- MSC-treated mice. The results of these experiments reveal that glucocorticoids increase the prevalence of ON, and agents that prevent loss of bone vascularity appear to prevent the development of ON. This intervention might be useful in patients with early stages of atraumatic ON.

Glucocorticoids decreased Cx43 expression in osteonecrosis of femoral head: The effect on proliferation and osteogenic differentiation of rat BMSCs

Glucocorticoid (GC)‐induced osteonecrosis of the femoral head (GC‐ONFH) is considered as one of the most serious side effects of long‐term or over‐dose steroid therapy. However, the underlying cause mechanisms are still not fully investigated. We firstly established a rat model of GC‐ONFH and injected lipopolysaccharide (LPS) and methylprednisolone (MPS). We found that the expressions of Cx43, Runx2, ALP and COLⅠ were more decreased than the normal group. Secondly, the isolated rat bone marrow stem cells (BMSCs) were treated with dexamethasone (Dex) in vitro, and the expressions of Cx43, Runx2, ALP and COLⅠ were decreased significantly. Moreover, the results of immunofluorescence staining, alizarin red staining, EdU assay and CCK8 showed that the osteogenic differentiation and the proliferation capacity of BMSCs were decreased after induced by Dex. A plasmid of lentivirus‐mediated Cx43 (Lv‐Cx43) gene overexpression was established to investigate the function of Cx43 in BMSCs under the Dex treatment. Findings demonstrated that the proliferation and osteogenic differentiation abilities were enhanced after Lv‐Cx43 transfected to BMSCs, and these beneficial effects of Lv‐Cx43 were significantly blocked when PD988059 (an inhibitor of ERK1/2) was used. In conclusion, the overexpression of Cx43 could promote the proliferation and osteogenic differentiation of BMSCs via activating the ERK1/2 signalling pathway, which provide a basic evidence for further study on the detailed function of Cx43 in GC‐ONFH.

Changes of lipid and bone metabolism in broilers with spontaneous femoral head necrosis

Blood biochemistry and bone metabolism were evaluated to investigate the etiology and mechanism of spontaneous femoral head necrosis (FHN) in broilers. According to the femoral head score of the fourth, fifth, and sixth week old FHN-affected broilers, they were divided into 3 groups, namely Normal group, femoral head separation group, and femoral head separation with growth plate lacerations group, and then carried out a comparative study. The results showed that the liver function (alanine aminotransferase and aspartate aminotransferase) and lipid metabolism (high-density lipoprotein and triglyceride) levels of broilers with spontaneous FHN were significant changed compared with the normal group. At the same time, accumulation of lipid droplets appeared in the liver, which illustrated that the occurrence of FHN may be related to lipid metabolism disorders. Tibia and femur parameters showed significant changes in bone mineral density and bone strength. The distribution of chondrocytes in the articular cartilage of broilers with FHN was irregular and vacuoles appeared, which indicated that cartilage homeostasis was destroyed. TUNEL staining showed that the apoptosis rate of articular chondrocytes in broilers with FHN in 6-week-old was significantly higher than that of normal broilers. Meanwhile, the bone markers (bone glaprotein and bone-specific alkaline phosphatase) changed significantly, indicating that the articular chondrocyte apoptosis and bone metabolism disorder may occur in FHN-affected birds. Therefore, FHN in broilers may be caused by dyslipidemia and abnormal bone metabolism.

Association of Neutrophil Extracellular Traps with the Development of Idiopathic Osteonecrosis of the Femoral Head

Idiopathic osteonecrosis of the femoral head (ONFH) is defined as necrosis of osteocytes due to a non-traumatic ischemia of the femoral head. Iatrogenic glucocorticoid administration and habitual alcohol intake are regarded as risk factors. It has been suggested that glucocorticoid-induced activation of platelets contributes to the local blood flow disturbance of the femoral head. Both activated platelets and alcohol can induce neutrophil extracellular traps (NETs). To determine the association of NETs with the development of idiopathic ONFH, surgically resected femoral heads of patients with idiopathic ONFH and osteoarthritis were assessed for existence of NET-forming neutrophils by immunofluorescence staining. NET-forming neutrophils were present in small vessels surrounding the femoral head of patients with idiopathic ONFH but not osteoarthritis. Moreover, Wistar-Kyoto rats were intravenously injected with NET-forming neutrophils or neutrophils without NET induction, and then the ischemic state of the tissue around the femoral head was evaluated by immunohistochemistry for hypoxia-inducible factor-1α. NET-forming neutrophils circulated into the tissue around the femoral head, and hypoxia-inducible factor-1α expression in the tissue was higher compared with that of rats intravenously administered with neutrophils without NET induction. Furthermore, ischemic change of osteocytes was observed in the femoral head of rats given an i.v. injection of NET-forming neutrophils. The collective findings suggest that NETs are possibly associated with the development of idiopathic ONFH.

IL-15 deficiency alleviates steroid-induced osteonecrosis of the femoral head by impact osteoclasts via RANKL-RANK-OPG system

Background

Whether IL-15 is involved in the development of steroid-induced osteonecrosis of the femoral head (ONFH) is investigated.

Methods

C57BL/6 J and l15^−/−mice were injected with methylprednisolone to induce wide type osteonecrosis (WT ON) and IL-15 deficiency osteonecrosis (IL-15^−/− ON). Hematoxylin-Eosin (H&E) staining and micro-computed tomography (micro-CT) scanning was used to detect the microstructure. The differentiation and formation of osteoclasts were determined with colony-forming unit-granulocyte macrophages (CFU-GM), colony-forming unit-macrophage/mononuclear (CFU-M) per tibia, and tartrate-resistant acid phosphatase (TRACP or TRAP) positive cells. Serum interleukin (IL)-15, osteocalcin, bone alkaline phosphatase (BAP), bone Gla protein (BGP), and TRACP were assayed with enzyme-linked immunosorbent assay (ELISA). The receptor activator of nuclear factor-κB (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG) in the femoral heads were detected by Western blot. CD34 staining was performed to detect microvascular density.

Results

IL-15 secretion was increased in the femoral heads and the serum of steroid-induced ONFH mice. IL-15 deficiency may lead to up-regulated vessel remodeling, improved microstructure, and up-regulated serum osteocalcin, BAP, and BGP secretion. Both the expression of RANKL/RANK/OPG and osteoclast differentiation and formation can be down-regulated by IL-15 deficiency.

Conclusion

IL-15 deficiency alleviates steroid-induced ONFH by impact osteoclasts via RANKL-RANK-OPG system.

Peripheral Blood Stem Cell Therapy Does Not Improve Outcomes of Femoral Head Osteonecrosis With Cap-Shaped Separated Cartilage Defect

A combination treatment with porous tantalum rod implantation and intra-arterial infusion of peripheral blood stem cells (PBSCs) provides a promise for treating early and intermediate stages of osteonecrosis of the femoral head (ONFH). However, its clinical indications and application restrictions remain unclear. This study aims to determine the clinical, histological, and radiological outcomes of a combination treatment using mechanical support and a targeted intra-arterial infusion of PBSCs for painful ONFH with a cap-shaped separation (CSS) cartilage defect. Compared with the standard pain management (control group), this combination treatment did not improve the Harris Hip Score (HHS) at 36 months. Micro-CT and histologic analyses showed severe focal destruction in all CSS-ONFH femoral heads in both the combination and control groups. Femoral heads showed a higher percentage of bone lesions in the combination treatment group than in the control group. There was no significant difference in osteoclast number in the subchondral bone areas between the two groups. A high level of expression of inflammatory cytokines, including tumor necrosis factor-α and interleukin-1β, was detected in blood vessels around the subchondral bone in both groups. The RANKL/OPG (receptor activator of the nuclear factor-kB ligand/osteoprotegerin) ratio was also similar between the control and combination treatment groups. Our results indicate that this combination treatment is not an effective method for the treatment of patients with painful CSS-ONFH. Moreover, this combination treatment did not inhibit inflammatory osteoclastogenesis in patients with more advanced disease. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:269-276, 2020.

The potential roles of circular RNAs in osteonecrosis of the femoral head (Review)

Circular RNAs (circRNAs) are categorized as non-coding RNAs that, unlike widely known canonical linear RNAs, form a covalently closed continuous loop without 5′ or 3′ polarities, which enables them to resist digestion by RNA exonucleases. Although the functions of circRNAs remain largely unknown, accumulated evidence has demonstrated that circRNAs can act as microRNA sponges, which allows them to regulate numerous biological processes and disease mechanisms, including apoptosis, angiogenesis, invasion, metastasis and stem cell differentiation. Although research into circRNAs is in its infancy, studies have identified critical roles for circRNAs in the initiation and progression of disease. The present study delineated the characteristics and functions of circRNAs, and focused on the potential relationship between circRNAs and osteonecrosis of the femoral head (ONFH). CircRNAs represent a novel avenue for studying the mechanisms underlying ONFH as well as possible treatments.

Exosomes derived from human CD34+ stem cells transfected with miR-26a prevent glucocorticoid-induced osteonecrosis of the femoral head by promoting angiogenesis and osteogenesis

Background

Damaged endothelial cells and downregulated osteogenic ability are two key pathogenic mechanisms of glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH). Recent studies suggested that transplantation of CD34⁺ stem cell-derived exosomes (CD34⁺-Exos) can treat ischemic diseases by promoting neovascularization and that miR-26a is an important positive regulator of osteogenesis. Moreover, the biological effect of exosomes is closely related to their cargo miRNAs. However, it is not clear whether increasing the abundance of miR-26a in CD34⁺-Exos will inhibit the progress of GC-induced ONFH.

Methods

MiR-26a was overexpressed in CD34⁺-Exos (miR-26a-CD34⁺-Exos) to increase their osteogenic potential. The angiogenic potential of miR-26a-CD34⁺-Exos was then examined through evaluations of migration and tube-forming capacities in vitro. In addition, in order to observe the osteogenic effect of miR-26a-CD34⁺-Exos on bone marrow stromal cells (BMSCs), Alizarin red staining, alkaline phosphatase (ALP) activity assays, and qPCR were carried out. Finally, miR-26a-CD34⁺-Exos were injected into a GC-induced ONFH rat model to prevent the progress of GC-induced ONFH. The biological effects of miR-26a-CD34⁺-Exos on the ONFH model were evaluated by micro-CT, angiography, and histological staining.

Results

Our data showed that miR-26a-CD34⁺-Exos enhanced human umbilical vein endothelial cell migration and tube-forming capacities. Furthermore, miR-26a-CD34⁺-Exos strengthened the osteogenic differentiation of BMSCs under the influence of GCs in vitro. Finally, the miR-26a-CD34⁺-Exos increased the vessel density and trabecular bone integrity of the femoral head in the GC-induced ONFH rat model, which inhibited the progress of ONFH.

Conclusions

MiR-26a-CD34⁺-Exos protect the femoral head from damage caused by GCs by strengthening angiogenesis and osteogenesis. The biological effect of miR-26a-CD34⁺-Exos make them suitable for application in the prevention of GC-induced ONFH.

Expression Profile Analysis of Differentially Expressed Circular RNAs in Steroid-Induced Osteonecrosis of the Femoral Head

Background

A growing number of studies have suggested that circular RNAs (circRNAs) serve as potential diagnostic biomarkers in many diseases. However, the role of circRNAs in steroid-induced osteonecrosis of the femoral head (SONFH) has not been reported.

Methods

Secondary sequencing was performed to profile circRNA expression in peripheral blood samples from three SONFH patients and three healthy individuals. We confirmed our preliminary findings by qRT-PCR. Bioinformatics analysis was conducted to predict their functions.

Results

The result showed 345 dysregulated circRNAs. qRT-PCR of eight selected circRNAs preliminarily confirmed the results, which were consistent with RNA sequencing. Bioinformatics analyses were performed to predict the functions of circRNAs to target the genes of miRNAs and the networks of circRNA-miRNA-mRNA interactions.

Conclusions

This study provides a new and fundamental circRNA profile of SONFH and a theoretical basis for further studies on the functions of circRNAs in SONFH.