Analysis of altered microRNA expression profile in the reparative interface of the femoral head with osteonecrosis

Preclinical models for studying corticosteroid-induced osteonecrosis of the femoral head

Nontraumatic osteonecrosis of the femoral head (ONFH) is a refractory condition that commonly results in femoral head collapse and degenerative arthritis of the hip. In the early stages, surgical procedures for hip preservation, including core decompression (CD), have been developed to prevent progressive collapse of the femoral head. Optimization of bone regeneration and biological augmentation may further enhance the therapeutic efficacy of CD for ONFH. Thus, combining CD with cell-based therapy has recently been proposed. In fact, patients treated with cell-based therapy using autologous bone marrow concentrate demonstrate improved survivorship of the femoral head, compared with conventional CD alone. Preclinical research studies to investigate adjunctive therapies for CD often utilize the rabbit model of corticosteroid-induced ONFH. Mesenchymal stem cells (MSCs) are known to promote osteogenesis and angiogenesis, and decrease inflammation in bone. Local drug delivery systems have the potential to achieve targeted therapeutic effects by precisely controlling the drug release rate. Scaffolds can provide an osteoconductive structural framework to facilitate the repair of osteonecrotic bone tissue. We focused on the combination of both cell-based and scaffold-based therapies for bone tissue regeneration in ONFH. We hypothesized that combining CD and osteoconductive scaffolds would provide mechanical strength and structural cell guidance; and that combining CD and genetically modified (GM) MSCs to express relevant cytokines, chemokines, and growth factors would promote bone tissue repair. We developed GM MSCs that overexpress the anti-inflammatory, pro-reconstructive cytokines platelet-derived growth factor-BB to provide MSCs with additional benefits and investigated the efficacy of combinations of these GM MSCs and scaffolds for treatment of ONFH in skeletally mature male New Zealand white rabbits. In the future, the long-term safety, efficacy, durability, and cost-effectiveness of these and other biological and mechanical treatments must be demonstrated for the patients affected by ONFH.

Prognostic and therapeutic potential of microRNAs for fracture healing processes and non-union fractures: A systematic review

BACKGROUND

Approximately 10% of all bone fractures result in delayed fracture healing or non-union; thus, the identification of biomarkers and prognostic factors is of great clinical interest. MicroRNAs (miRNAs) are known to be involved in the regulation of the bone healing process and may serve as functional markers for fracture healing.

AIMS AND METHODS

This systematic review aimed to identify common miRNAs involved in fracture healing or non-union fractures using a qualitative approach. A systematic literature search was performed with the keywords 'miRNA and fracture healing' and 'miRNA and non-union fracture'. Any original article investigating miRNAs in fracture healing or non-union fractures was screened. Eventually, 82 studies were included in the qualitative analysis for 'miRNA and fracture healing', while 19 were selected for the 'miRNA and fracture non-union' category.

RESULTS AND CONCLUSIONS

Out of 151 miRNAs, miR-21, miR-140 and miR-214 were the most investigated miRNAs in fracture healing in general. miR-31-5p, miR-221 and miR-451-5p were identified to be regulated specifically in non-union fractures. Large heterogeneity was detected between studies investigating the role of miRNAs in fracture healing or non-union in terms of patient population, sample types and models used. Nonetheless, our approach identified some miRNAs with the potential to serve as biomarkers for non-union fractures, including miR-31-5p, miR-221 and miR-451-5p. We provide a discussion of involved pathways and suggest on alignment of future research in the field.

Therapeutic perspectives of exosomes in glucocorticoid-induced osteoarthrosis

Exosomes are widely involved in a variety of physiological and pathological processes. These important roles are also hidden in the physiological processes related to bone. Chondrocytes, osteoblasts, synovial fibroblasts, and bone marrow mesenchymal stem cells produce and secrete exosomes, thereby affecting the biology process of target cells. Furthermore, in the primary pathogenesis of osteoarthrosis induced by steroid hormones, mainly involve glucocorticoid (GC), the exosomes have also widely participated. Therefore, exosomes may also play an important role in glucocorticoid-induced osteoarthrosis and serve as a promising treatment for early intervention of osteoarthrosis in addition to playing a regulatory role in malignant tumors. This review summarizes the previous results on this direction, systematically combs the role and therapeutic potential of exosomes in GC-induced osteoarthrosis, discusses the potential role of exosomes in the treatment and prevention of GC-induced osteoarthrosis, and reveals the current challenges we confronted.

Knowledge structure and emerging trends on osteonecrosis of the femoral head: a bibliometric and visualized study

Background

Osteonecrosis of the femoral head (ONFH) is a common disabling disease with considerable social and economic impacts. Although extensive studies related to ONFH have been conducted in recent years, a specific bibliometric analysis on this topic has not yet been performed. Our study attempted to summarize the comprehensive knowledge map, development landscape, and future directions of ONFH research with the bibliometric approach.

Methods

All publications concerning ONFH published from 2001 to 2020 were identified from Web of Science Core Collection. Key bibliometric indicators were calculated and evaluated using CiteSpace, VOSviewer, and the online bibliometric analysis platform.

Results

A total of 2594 publications were included. Our analysis revealed a significant exponential growth trend in the annual number of publications over the past 20 years (R² = 0.9663). China, the USA, and Japan were the major contributors both from the quality and quantity points of view. Correlation analysis indicated that there was a high positive correlation between the number of publications and gross domestic product (r = 0.774), and a moderate positive correlation between publications and demographic factor (r = 0.673). All keywords were categorized into four clusters including Cluster 1 (etiology and risk factors study); Cluster 2 (basic research and stem cell therapy); cluster 3 (hip-preserving study); and Cluster 4 (hip replacement study). Stem cell therapy-related research has been recognized as an important research hotspot in this field. Several topics including exosomes, autophagy, biomarkers, osteogenic differentiation, microRNAs, steroid-induced osteonecrosis, mesenchymal stem cells, double-blind, early-stage osteonecrosis, and asymptomatic osteonecrosis were considered as research focuses in the near future.

Conclusion

Over the past two decades, increasing attention has been paid to global ONFH-related research. Our bibliometric findings provide valuable information for researchers to understand the basic knowledge structure, identify the current research hotspots, potential collaborators, and future research frontiers in this field.

miR-122-5p targets GREM2 to protect against glucocorticoid-induced endothelial damage through the BMP signaling pathway

Glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH) accounts for a big portion of non-traumatic ONFH; nevertheless, the pathogenesis has not yet been fully understood. GC-induced endothelial dysfunction might be a major contributor to ONFH progression. The Gene Expression Omnibus (GEO) dataset was analyzed to identify deregulated miRNAs in ONFH; among deregulated miRNAs, the physiological functions of miR-122-5p on ONFH and endothelial dysfunction remain unclear. In the present study, miR-122-5p showed to be under-expressed within GC-induced ONFH femoral head tissues and GC-stimulated bone microvascular endothelial cells (BMECs). In human umbilical vein endothelial cells (HUVECs) and BMECs, GC stimulation significantly repressed cell viability, promoted cell apoptosis and increased the mRNA expression of proinflammatory cytokines, such as TNF-α, IL-1β, and IFN-γ. After overexpressing miR-122-5p, GC-induced endothelial injuries were attenuated, as manifested by rescued cell viability, cell migration, and tube formation capacity. Regarding the BMP signaling, GC decreased the protein levels of BMP-2/6/7 and SMAD-1/5/8, whereas miR-122-5p overexpression significantly attenuated the inhibitory effects of GC on these proteins. Online tool and experimental analyses revealed the direct binding between miR-122-5p and GREM2, a specific antagonist of BMP-2. In contrast to miR-122-5p overexpression, GREM2 overexpression aggravated GC-induced endothelial injury; GREM2 silencing partially eliminated the effects of miR-122-5p inhibition on GC-stimulated HUVECs and BMECs. Finally, GREM2 silencing reversed the suppressive effects of GC on BMP-2/6/7 and SMAD-1/5/8, and attenuated the effects of miR-122-5p inhibition on these proteins upon GC stimulation. Conclusively, the present study demonstrates a miR-122-5p/GREM2 axis modulating the GC-induced endothelial damage via the BMP/SMAD signaling. Considering the critical role of endothelial function in ONFH pathogenesis, the in vivo role and clinical application of the miR-122-5p/GREM2 axis is worthy of further investigation.

Icariin regulates miR-23a-3p-mediated osteogenic differentiation of BMSCs via BMP-2/Smad5/Runx2 and WNT/β-catenin pathways in osteonecrosis of the femoral head

Icariin is commonly used for the clinical treatment of osteonecrosis of the femoral head (ONFH). miR-23a-3p plays a vital role in regulating the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). The present study aimed to investigate the roles of icariin and miR-23a-3p in the osteogenic differentiation of BMSCs and an ONFH model. BMSCs were isolated and cultured in vitro using icariin-containing serum at various concentrations, and BMSCs were also transfected with a miR-23a inhibitor. The alkaline phosphatase (ALP) activity and cell viability as well as BMP-2/Smad5/Runx2 and WNT/β-catenin pathway-related mRNA and protein expression were measured in BMSCs. Additionally, a dual-luciferase reporter assay and pathway inhibitors were used to verify the relationship of icariin treatment/miR-23a and the above pathways. An ONFH rat model was established in vivo, and a 28-day gavage treatment and lentivirus transfection of miR-23a-3p inhibitor were performed. Then, bone biochemical markers (ELISA kits) in serum, femoral head (HE staining and Digital Radiography, DR) and the above pathway-related proteins were detected. Our results revealed that icariin treatment/miR-23a knockdown promoted BMSC viability and osteogenic differentiation as well as increased the mRNA and protein expression of BMP-2, BMP-4, Runx2, p-Smad5, Wnt1 and β-catenin in BMSCs and ONFH model rats. In addition, icariin treatment/miR-23a knockdown increased bone biochemical markers (ACP-5, BAP, NTXI, CTXI and OC) and improved ONFH in ONFH model rats. In addition, a dual-luciferase reporter assay verified that Runx2 was a direct target of miR-23a-3p. These data indicated that icariin promotes BMSC viability and osteogenic differentiation as well as improves ONFH by decreasing miR-23a-3p levels and regulating the BMP-2/Smad5/Runx2 and WNT/β-catenin pathways.

Association between Genetic Polymorphisms of MIR3142HG and the Risk of Steroid-Induced Osteonecrosis of the Femoral Head in the Population of Northern China

BACKGROUND

Steroid-induced osteonecrosis of the femoral head (ONFH) is aseptic necrosis of the femoral head caused by glucocorticoid use. Once necrotic femoral head necrosis occurs, it irreversibly affects the quality of life seriously. Studies have shown that the susceptibility to steroid-induced ONFH is likely to be related to the variation of miRNA-coding genes. Therefore, this study aimed was to investigate the effect of MIR3142HG on steroid-induced ONFH.

METHODS

Agena MassARRAY was used to genotype MIR3142HG gene rs1582417, rs2431689, rs7727155, and rs17057846 in 199 patients and 725 healthy people. A genetic model and haplotype analysis were used to evaluate the relationship between the MIR3142HG polymorphism and the risk of steroid-induced ONFH. The odds ratio and 95% confidence intervals were obtained through logistic regression to assess the influence of gene polymorphisms on the occurrence of steroid-induced ONFH.

RESULTS

The consequences show that rs7727115 is a protective factor, it could reduce the risk of steroid-induced ONFH, and rs1582417 could increase the risk of steroid-induced ONFH. In the genetic model, rs1582417 was associated with increased risk of alcohol-induced ONFH in dominant model and log-additive model. rs7727115 showed a decreased risk in codominant model, dominant model, and log-additive model. In addition, rs2431689 is related to HDL-C (p = 0.012) and ApoA1 (p = 0.010) levels, and rs17057846 (p = 0.024) is related to ApoB levels. Thelinkage analysis indicated 3 single-nucleotide polymorphisms (rs2431689, rs7727115, and rs17057846) in MIR3142HG with significant chain imbalance. In addition, haplotype "GGG" of MIR3142HG was found out and is harmful for steroid-induced ONFH.

CONCLUSION

Our results first confirm that the genetic polymorphism of MIR3142HG is associated with steroid-induced ONFH susceptibility in Chinese Han population.

Reciprocal effect of microRNA-224 on osteogenesis and adipogenesis in steroid-induced osteonecrosis of the femoral head

The adverse effects of glucocorticoids (GCs) on bone marrow stromal stem cells (BMSCs) play an important role in steroid-induced osteonecrosis of the femoral head (ONFH). Our previous miRNA microarray analysis indicated that microRNA-224-5p (miR-224-5p) could be a potential regulator; however, the underlying mechanism remains unclear. In the present study, we demonstrated that miR-224-5p was upregulated in GC-treated BMSCs, and functional experiments revealed that miR-224-5p could suppress osteogenic but promote adipogenic differentiation of BMSCs. Smad4 was identified as a direct target gene of miR-224-5p, and the Smad4-Taz axis was confirmed as the regulatory pathway for adipo-osteogenic differentiation of BMSCs. Our in vivo experiments further confirmed that the miR-224-5p antagomir could alleviate the inhibitory effects of GCs and facilitate bone formation in steroid-induced ONFH models. Therefore, these findings provide insight into the function of miR-224-5p as a reciprocal regulator of the adipo-osteogenic differentiation of BMSCs, and it could serve as a novel therapeutic target for steroid-induced ONFH.

Non-coding RNA Identification in Osteonecrosis of the Femoral Head Using Competitive Endogenous RNA Network Analysis

OBJECTIVE

To investigate the regulatory network of long non-coding RNA (lncRNA) as competing endogenous RNAs (ceRNAs) in osteonecrosis of the femoral head (ONFH).

METHODS

The gene expression profile GSE74089 of ONFH and microRNA (miRNA) expression profile of GSE89587 were obtained from the Gene Expression Omnibus (GEO) database. The GSE74089 contained four ONFH samples and four controls. The GSE89587 included 10 ONFH samples and 10 control samples. The differentially expressed lncRNAs (DE-lncRNAs) and DE-mRNAs between ONFH group and control group were identified from GSE74089 using the limma package based on criteria of adjusted P value <0.05 and |log fold change (FC)| ≥2. The DEmiRNAs between ONFH group and control group were screened from GSE89587 on the basis of adjusted P value <0.05. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway for DE-mRNAs were analyzed using DAVID 6.7 and GSEA 3.0, respectively. Coexpressed lncRNA-mRNA pairs were identified by corr.test method in R based on the criteria of adjusted P value <0.01 and |r| ≥ 0.9. A ceRNA network was constructed and visualized using cytoscape 3.7.0 by integrating the DE-lncRNA, DE-miRNA, and DEmRNA data. The key mRNAs and lncRNAs in the ceRNA network were further validated in an independent dataset of GSE123568.

RESULTS

Based on our analysis, a total of 28 DE-lncRNAs, 1403 DE-mRNAs, and 134 DE-miRNAs were identified, respectively. The DE-mRNAs were significantly enriched in the function of "skeletal system development," "collagen fibril organization," "blood vessel development," and "regulation of nervous system development." Besides, 72 KEGG pathways, including eight active pathways and 64 suppressed pathways were identified, including which immune pathway was the most significantly activated one and which ribosome-related function was the most suppressed. A co-expression network including 161 DE-mRNAs and 16 DE-lncRNAs was built. Highly connected nodes were identified among lncRNAs such as H19, C20orf203, LINC00355, SFTA3, CRNDE, CASC2, LINC00494, C9orf163, C10orf91, and LINC00301. The ceRNA network indicated that lncRNA H19 functioned as a ceRNA of hsa-miR-519b-3p and hsa-miR-296-5p in ANKH and ECHDC1 regulation; lncRNA C9orf163 functioned as a ceRNA of hsa-miR-424-5p in CCNT1 regulation. The expression trends of ANKH, CCNT1, and C9orf163 were successfully validated in independent dataset of GSE123568.

CONCLUSION

The ceRNAs of lncRNA H19- hsa-miR-519b-3p/hsa-miR-296-5p-ANKH and lncRNA c9orf163- hsa-miR-424-5p-CCNT1 might play important roles in ONFH development. Our research provided an understanding of the important role of lncRNA-related ceRNAs in ONFH.

Resveratrol prevents steroid-induced osteonecrosis of the femoral head via miR-146a modulation

The purpose of this study was to investigate the possible use of resveratrol (Res) to reverse abnormal osteogenesis/osteoclastogenesis activity that occurs during femoral head osteonecrosis and to explore the detailed mechanisms. Application of Res to bone marrow-derived mesenchymal stem cells in vitro promoted survival, inhibited apoptosis, and downregulated expression of reactive oxygen species expression. Moreover, Res application was associated with elevated microRNA-146a (miR-146a) expression, osteogenic differentiation, and suppressed osteoclastic differentiation, which were markedly reversed by miR-146a inhibitor. Histopathological observations and micro-computed tomography scanning results indicated that the Res-treated group had lower incidence of osteonecrosis and better bone microstructure than the untreated group. Res inhibited osteoclastogenesis through altering the levels of sirtuin1 (Sirt1), nuclear transcription factor-κB (NF-κB), and receptor activator of NF-κB ligand (RANKL). Simultaneously, Res treatment improved bone formation and increased β-catenin and runt-related transcription factor 2 (Runt2) expression levels, while reducing forkhead box class O (FOXO) family protein levels. The results of our study suggest that Res prevents steroid-induced osteonecrosis by upregulating miR-146a, and thereby stabilizes osteogenesis/osteoclastogenesis homeostasis via Wnt/FOXO and Sirt1/NF-κB pathways.

Differentially expressed microRNAs as diagnostic biomarkers for infected tibial non-union

BACKGROUND

Infected tibial non-union is a challenging clinical complication of fracture treatment. Improper treatment of infected tibial non-union may result in high treatment costs and a long treatment period, and lead to medical disputes and decreased patient satisfaction. An increasing number of studies have indicated the significant role of microRNAs (miRNAs) in the development and progression of different bone diseases. Therefore, the identification of a specific miRNA expression profile associated with infected tibial non-union is a key step toward establishing a novel strategy for the diagnosis and treatment of infected tibial non-union.

METHODS

We utilised a microarray analysis to compare the specific expression of bone tissue miRNA in patients with infected tibial non-union and closed tibial fractures. Quantitative real-time reverse transcription-polymerase chain reaction was performed to validate the microarray results. Receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic efficacy of the identified regulated miRNA(s) isolated from bone tissue as potential biomarker(s).

RESULTS

Microarray analysis showed 20 differentially expressed miRNAs. Differential expression of miR-649, miR-29b-3p, miR-498, miR-365a-5p, miR-328-5p, and miR-345-3p was further confirmed in a validation cohort. ROC curve analyses showed an AUC (Areas Under the ROC Curve) of 0.808 (95% confidence interval [CI]: 0.675-0.940), 0.778 (95% CI: 0.634-0.921), 0.769 (95% CI: 0.619-0.919), 0.798 (95% CI: 0.662-0.933), 0.818 (95% CI: 0.690-0.945), 0.839 (95% CI: 0.715-0.963) for miR-649, miR-29b-3p, miR-498, miR-365a-5p, miR-328-5p, and miR-345-3p, respectively. The combined use of three miRNAs (miR-649, miR-328-5p, and miR-345-3p) yielded an overall diagnostic accuracy of AUC = 0.953, indicating a robust diagnostic value.

CONCLUSION

Our findings highlight the role of miR-649, miR-328-5p, and miR-345-3p as novel candidate biomarkers for infected tibial non-union diagnosis, suggesting that these differentially expressed miRNAs could be utilised as novel diagnostic and therapeutic tools to identify infected tibial non-union.

Bioinformatics analysis of microRNA linked to ubiquitin proteasome system in traumatic osteonecrosis of the femoral head

MicroRNAs (miRNAs) have been suggested to act critical roles in the pathophysiology of traumatic osteonecrosis of the femoral head (TONFH). Unfortunately, their roles in the development of TONFH are still ambiguous. The purpose of this study is to identify promising miRNA biomarkers in traumatic osteonecrosis development.We conducted a comprehensive bioinformatics analysis using microarray datasets downloaded from the Gene Expression Omnibus database, and compared the expression of miRNAs in the serum of TONFH patients with controls. Next, we performed target prediction, function enrichment analysis, and protein-protein interaction network analysis based on differentially expressed (DE) miRNAs.We identified 26 DE miRNAs that may contribute to the pathophysiology of TONFH. The miRNAs were linked to ubiquitin proteasome system including conjugating protein ligase activity, ubiquitin-protein ligase activity and ubiquitin mediated proteolysis 5 pathway, and we exposed miR-181a-5p and miR-140-5p as promising biomarkers in TONFH.A predicting model consisting of 5 miRNAs may help discriminating high-risk patients who might develop TONFH after femur neck fracture. Among DE miRNAs, MiR-181a-5p and miR-140-5p may contribute to the development femoral head osteonecrosis after femur neck fracture via ubiquitin proteasome system.

MiR-144-3p Inhibits BMSC Proliferation and Osteogenic Differentiation Via Targeting FZD4 in Steroid-Associated Osteonecrosis

BACKGROUND

MicroRNAs have recently been recognized to be engaged in the development of bone diseases.

OBJECTIVE

This study was performed to elucidate the effects of miR-144-3p on proliferation and osteogenesis of mesenchymal stem cells (MSCs) from the patients with steroid-associated osteonecrosis (ONFH) and its related mechanism.

METHOD

The expression level of miR-144-3p in the MSCs from the proximal femur of the patients was examined by Real-time PCR. The cell proliferation ability was assayed by MTT. The differentiation ability of MSCs was assayed by Alizarin Red S (ARS) staining. The interaction between miR-144-3p and frizzled4 (FZD4) was investigated by Real-time PCR, western blot and luciferase reporter assay.

RESULTS

ONFH samples had the obviously high expression of miR-144-3p compared to the control. MiR-144-3p had a negative effect on the proliferation and osteogenesis of MSCs. Via targeting FZD4, miR-144-3p decreased β-catenin nuclear translocation, the transcription of RUNX2 and COL1A1. Over-expression of FZD4 partially reversed miR-144-3p-induced decrease in the proliferation and osteogenesis of MSCs.

CONCLUSION

MiR-144-3p might play an important role in the development of ONFH and might be used as a novel class of therapeutic targets for this disease.

BMSC-derived exosomes carrying microRNA-122-5p promote proliferation of osteoblasts in osteonecrosis of the femoral head

Mesenchymal stem cells (MSCs) with multipotential differentiation capacity can differentiate into bone cells under specific conditions and can be used to treat osteonecrosis (ON) of the femoral head (ONFH) through cell transplantation. The current study aims to explore the role of bone marrow (BM) MSCs (BMSCs)-derived exosomes carrying microRNA-122-5p (miR-122-5p) in ONFH rabbit models.First, rabbit models with ONFH were established. ONFH-related miRNAs were screened using the Gene Expression Omnibus (GEO) database. A gain-of-function study was performed to investigate the effect of miR-122-5p on osteoblasts and BMSCs and effects of exosomes carrying miR-122-5p on ONFH. Co-culture experiments for osteoblasts and BMSCs were performed to examine the role of exosomal miR-122-5p in osteoblast proliferation and osteogenesis. The target relationship between miR-122-5p and Sprouty2 (SPRY2) was tested.MiR-122, significantly decreased in ONFH in the GSE89587 expression profile, was screened. MiR-122-5p negatively regulated SPRY2 and elevated the activity of receptor tyrosine kinase (RTK), thereby promoting the proliferation and differentiation of osteoblasts. In vivo experiments indicated that bone mineral density (BMD), trabecular bone volume (TBV), and mean trabecular plate thickness (MTPT) of femoral head were increased after over-expressing miR-122-5p in exosomes. Significant healing of necrotic femoral head was also observed.Exosomes carrying over-expressed miR-122-5p attenuated ONFH development by down-regulating SPRY2 via the RTK/Ras/mitogen-activated protein kinase (MAPK) signaling pathway. Findings in the present study may provide miR-122-5p as a novel biomarker for ONFH treatment.

Study of Osteocyte Behavior by High-Resolution Intravital Imaging Following Photo-Induced Ischemia

Ischemic injuries and local hypoxia can result in osteocytes dysfunction and play a key role in the pathogenesis of avascular osteonecrosis. Conventional imaging techniques including magnetic resonance imaging (MRI) and computed tomography (CT) can reveal structural and functional changes within bony anatomy; however, characterization of osteocyte behavioral dynamics in the setting of osteonecrosis at the single cell resolution is limited. Here, we demonstrate an optical approach to study real-time osteocyte functions in vivo. Using nicotinamide adenine dinucleotide (NADH) as a biomarker for metabolic dynamics in osteocytes, we showed that NADH level within osteocytes transiently increase significantly after local ischemia through non-invasive photo-induced thrombosis of afferent arterioles followed by a steady decline. Our study presents a non-invasive optical approach to study osteocyte behavior through the modulation of local environmental conditions. Thus it provides a powerful toolkit to study cellular processes involved in bone pathologies in vivo.

Differentially Expressed MicroRNAs in Conservatively Treated Nontraumatic Osteonecrosis Compared with Healthy Controls

Deregulation of microRNAs (miRNAs) contributes to nontraumatic osteonecrosis of the femoral head (ONFH-N), but the differentially expressed circulating miRNAs in patients with ONFH-N receiving nonsurgical therapy are unknown. This study aimed to determine the miRNAs expression profile of patients with ONFH-N receiving conservative treatments. This was a case-control prospective study of 43 patients with ONFH-N and 43 participants without ONFH-N, enrolled from 10/2014 to 10/2016 at the Department of Orthopedics of the Linyi People's Hospital (China). The two groups were matched for age, gender, and living area. Microarray analysis and quantitative RT-PCR were used to examine the differentially expressed miRNAs. Bioinformatics was used to predict miRNA target genes and signaling pathways. Microarray and quantitative RT-PCR revealed that nine miRNAs were downregulated and five miRNAs were upregulated in ONFH-N (n = 3) compared with controls (n = 3). Bioinformatics showed that calcium-mediated signaling pathway, regulation of calcium ion transmembrane transporter activity, cytoskeletal protein binding, and caveolae macromolecular signaling complex were probably regulated by the identified differentially expressed miRNAs. In the remaining 80 subjects (n = 40/group), miR-335-5p was downregulated (P = 0.01) and miR-100-5p was upregulated (P = 0.02) in ONFH-N compared with controls. In conclusion, some miRNAs are differentially expressed in conservatively treated ONFH-N compared with controls. Those miRNAs could contribute to the pathogenesis of ONFH-N.

MicroRNA-mediated interacting circuits predict hypoxia and inhibited osteogenesis of stem cells, and dysregulated angiogenesis are involved in osteonecrosis of the femoral head

PURPOSE

MicroRNAs (miRNAs) are associated with various pathologic conditions and can serve as diagnostic or therapeutic biomarkers. This study tried to identify the differentially expressed miRNAs to predict the possible pathomechanisms involved in osteonecrosis of the femoral head (ONFH).

METHODS

We compared the peripheral blood miRNAs in 46 patients with ONFH and 85 healthy controls by microarray and droplet digital polymerase chain reaction (ddPCR). Putative interacted networks between the differentially responded miRNAs were analyzed by web-based bioinformatics prediction tools.

RESULTS

Microarray identified 51 differentially expressed miRNAs with at least twofold change (upregulation in 34 and downregulation in 17), and the results were validated by ddPCR using six selected miRNAs. Bioinformatics genetic network analysis focusing on the six miRNAs found the upregulated miR-18a and miR-19a are associated with angiogenesis after induction of ischemia; the upregulated miR-138-1 can inhibit osteogenic differentiation of mesenchymal stem cells; the most targeted genes, p53 and SERBP1, are associated with hypoxia and hypofibrinolysis.

CONCLUSIONS

This study combined the miRNA analysis with the bioinformatics and predicts that hypoxia, inhibited osteogenesis of stem cells, and dysregulated angiogenesis might be orchestrated through the miRNA interacting circuits in the pathogenesis of ONFH.

Intermittent cyclic mechanical tension altered the microRNA expression profile of human cartilage endplate chondrocytes

Previous studies have identified the association between cartilage endplate (CEP) degeneration and abnormal mechanical loading. Several studies have reported that intermittent cyclic mechanical tension (ICMT) regulates CEP degeneration via various biological processes and signaling pathways. However, the functions of microRNAs in regulating the cellular responses of CEP chondrocytes to ICMT remain to be elucidated. The current study determined the differentially expressed microRNAs in human CEP chondrocytes exposed to ICMT using microarray analysis. A total 21 significantly upregulated and 62 downregulated miRNAs were identified compared with the control. The findings were subsequently partially validated by reverse transcription-quantitative polymerase chain reaction. Potential target genes of the significantly differentially expressed miRNAs were predicted using bioinformatics analysis and were used for Gene Ontology analysis and Kyoto Encyclopedia of Genes and Genomes pathway analysis. The present study revealed that the significantly differentially expressed microRNAs were involved in various signaling pathways and biological processes that are crucial to regulating the responses of CEP chondrocytes to ICMT. The current study provided a global view of microRNA expression in CEP chondrocytes under mechanical stimulation, suggesting that microRNAs are important for regulating the mechanical response of CEP chondrocytes. Additionally, it provided a novel insight into the association between mechanical stress and the establishment and progression of intervertebral disc degeneration.

Regulatory effect of microRNA-34a on osteogenesis and angiogenesis in glucocorticoid-induced osteonecrosis of the femoral head

Glucocorticoid-induced osteonecrosis of the femoral head (GIOFH) is a common and devastating orthopedic disease, and its underlying mechanism remains unclear. The aim of this study was to determine the role of microRNA-34a (mir-34a) in GIOFH. C57 mouse mesenchymal stem cells (mMSCs) and human umbilical vein endothelial cells (HUVECs) were cultured with dexamethasone (Dex). A total of 48 adult rats were treated with glucocorticoids, and after the onset of GIOFH, each femoral head was removed. Mir-34a mimics, an inhibitor and over-expressing lentivirus were used in vitro and in vivo, respectively. Real-time PCR, immunohistochemistry, ELISA, cell proliferation assays, osteoblastic differentiation, and endothelial activity assays were employed to evaluate the effect of mir-34a on mMSCs, osteoblasts, and vascular endothelial cells in glucocorticoid-treated mice. We found that Dex inhibited mMSC proliferation and osteoblastic differentiation, as well as the viability and activity of endothelial cells. Dex also caused osteonecrosis and decreased new vessel formation in vivo. Mir-34a alleviated the inhibitory effects of Dex on mMSCs and osteoblasts, while facilitating its inhibitory effects on endothelial cells. Mir-34a is an important regulator in osteogenesis and angiogenesis, and it might be useful as a therapeutic target for GIOFH. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:417-424, 2018.

N-AC-l-Leu-PEI-mediated miR-34a delivery improves osteogenic differentiation under orthodontic force

Rare therapeutic genes or agents are reported to control orthodontic bone remodeling. MicroRNAs have recently been associated with bone metabolism. Here, we report the in vitro and in vivo effects of miR-34a on osteogenic differentiation under orthodontic force using an N-acetyl-L-leucine-modified polyethylenimine (N-Ac-l-Leu-PEI) carrier. N-Ac-l-Leu-PEI exhibited low cytotoxicity and high miR-34a transfection efficiency in rat bone mineral stem cells and local alveolar bone tissue. After transfection, miR-34a enhanced the osteogenic differentiation of Runx2 and ColI, Runx2 and ColI protein levels, and early osteogenesis function under orthodontic strain in vitro. MiR-34a also enhanced alveolar bone remodeling under orthodontic force in vivo, as evidenced by elevated gene and protein expression, upregulated indices of alveolar bone anabolism, and diminished tooth movement. We determined that the mechanism miR-34a in osteogenesis under orthodontic force may be associated with GSK-3β. These results suggested that miR-34a delivered by N-Ac-l-Leu-PEI could be a potential therapeutic target for orthodontic treatment.

Emerging roles of MicroRNAs in osteonecrosis of the femoral head

Osteonecrosis of the femoral head (ONFH) is one of the most common orthopaedic diseases. The exact pathogenic mechanism of ONFH is still unknown. MicroRNAs (miRNAs) are a class of non-coding RNAs that negatively modulate gene expression at post-transcriptional level. An increasing number of studies have shown that miRNAs play crucial roles in different physiological processes, including development, cell proliferation, differentiation and metabolism. Recently, multiple studies demonstrated that miRNAs are involved in the pathogenesis of ONFH. In this review, we summarize dysregulated miRNAs and their functions in ONFH. Furthermore, we discuss their potential clinical applications for diagnosis and treatment of ONFH.

Bioinformatics and Microarray Analysis of miRNAs in Aged Female Mice Model Implied New Molecular Mechanisms for Impaired Fracture Healing

Impaired fracture healing in aged females is still a challenge in clinics. MicroRNAs (miRNAs) play important roles in fracture healing. This study aims to identify the miRNAs that potentially contribute to the impaired fracture healing in aged females. Transverse femoral shaft fractures were created in adult and aged female mice. At post-fracture 0-, 2- and 4-week, the fracture sites were scanned by micro computed tomography to confirm that the fracture healing was impaired in aged female mice and the fracture calluses were collected for miRNA microarray analysis. A total of 53 significantly differentially expressed miRNAs and 5438 miRNA-target gene interactions involved in bone fracture healing were identified. A novel scoring system was designed to analyze the miRNA contribution to impaired fracture healing (RCIFH). Using this method, 11 novel miRNAs were identified to impair fracture healing at 2- or 4-week post-fracture. Thereafter, function analysis of target genes was performed for miRNAs with high RCIFH values. The results showed that high RCIFH miRNAs in aged female mice might impair fracture healing not only by down-regulating angiogenesis-, chondrogenesis-, and osteogenesis-related pathways, but also by up-regulating osteoclastogenesis-related pathway, which implied the essential roles of these high RCIFH miRNAs in impaired fracture healing in aged females, and might promote the discovery of novel therapeutic strategies.

MicroRNA-145 Mediates Steroid-Induced Necrosis of the Femoral Head by Targeting the OPG/RANK/RANKL Signaling Pathway

Objective

To investigate the role of microRNA-145 (miR-145) in steroid-induced necrosis of the femoral head (SINFH) by evaluating its effects on the OPG/RANK/RANKL signaling pathway.

Methods

A rat model of SINFH was constructed via injection of the lentiviral vector pLV-shRNA-miR-145. Pathological observation was performed via tartrate-resistant acid phosphatase (TRAP) staining, and serum OPG levels were detected by ELISA. The mRNA expression levels of miR-145, OPG, RANK and RANKL in THP-1 cells were assessed by RT-PCR, and the protein expression levels of OPG, RANK and RANKL were assessed by western blotting.

Results

The expression of miR-145 in the lentivirus-mediated miR-145 group was significantly up-regulated compared with that in the control and normal groups (both P < 0.01). Serum OPG levels were decreased in SINFH rats compared with control and normal rats. The mRNA and protein expression levels of OPG in THP-1 cells decreased after transfection (all P < 0.05). By contrast, the mRNA and protein expression levels of RANK and RANKL in THP-1 cells increased after transfection (all P < 0.05). After transfection of 293T cells with an miR-145 overexpression vector, miR-145 expression in 293T cells increased significantly, while OPG mRNA and protein expression decreased significantly (all P < 0.05).

Conclusion

MiR-145 plays a role in the occurrence of SINFH by targeting the OPG/RANK/RANKL signaling pathway.

Differential expression of miR-672-5p and miR-146a-5p in osteoblasts in rats after steroid intervention

BACKGROUND

Apoptosis of osteoblasts and osteocytes is one cause of steroid-induced osteonecrosis of the femoral head; however, the molecular mechanism of steroid affecting osteoblasts at the genetic level is unclear. The aim of the present work is to examine differential expression of osteoblasts in rats after steroid intervention and to verify expression by real-time polymerase chain reaction (RT-PCR).

METHODS

Primary culture, passaging and identification of osteoblasts of SD neonatal rats were conducted; osteoblasts were divided into two groups, the control group, and the steroid group. Total RNA was extracted separately, and quality control was performed; by means of RNA labeling and microarray hybridization, data were collected and then standardized to ascertain differences in miRNA expression between the two groups. The gene expression spectrum was analyzed. Obvious differential expression of miR-672-5p and miR-146a-5p was verified by RT-PCR. Miranda, microcosm and mirdb bioinformatics software were used to predict target genes.

RESULTS

Compared with the control group, morphologically, the osteoblasts in the steroid group were more irregular and showed various shapes. The number of miRNAs (fold change >2) in the steroid group was six. Four miRNAs were upregulated and two miRNAs were downregulated. In particular, upregulated miR-672-5p expression and downregulated miR-146a-5p expression were significant. RT-PCR results showed that the 2(-△△) CT value of miR-672-5p in the steroid group was 3.743-fold of that in the control group, and the 2(-△△) CT value of miR-146a-5p in the steroid group was 0.322-fold of that in the control group. Angptl4, Ccdc51, Ssbp3 and RGD1306991 were predicted as the target gene of miR-672-5p, while Hrp12 was that of miR-146a-5p.

CONCLUSION

Expression profiles of miR-672-5p and miR-146a-5p had the most significant changes in the osteoblasts of rats with steroid intervention, which may provide a new viewpoint to pathogenesis of osteonecrosis of the femoral head.

Involvement of MicroRNA-210 Demethylation in Steroid-associated Osteonecrosis of the Femoral Head

Angiogenesis is an important event in steroid-associated osteonecrosis of the femoral head (SONFH). Here we performed miRNA microarray with SONFH tissues (ONs) and the adjacent normal tissues (NLs) to select the angiogenic miRNA. The results showed that miR-210 was differentially expressed in SONFH versus normal tissues. Unexpectedly, its specific transcription factor, hypoxia-inducible factor-1α, was shown of no significant changes in ONs compared with NLs. Further Bisulfite sequencing revealed that miR-210 is embedded in a CpG island and miR-210 gene has 2 CpG sites with lower methylation percentage in ONs compared with NLs. Additionally, ONs with lower miR-210 gene methylation exhibited higher miR-210 expression. Next, we found that the endothelial cells treated with demethylating agents could significantly increase the expression of miR-210, along with promoted cell viability and differentiation. Some angiogenic genes (VEGF, bFGF, TNF-α and PCNA) were up-regulated as well. In addition, the supernatant of the cells after demethylation treatment displayed an enhanced ability of recruiting new microvessels in vivo. Taken together, our study not only provides novel insights into the regulation of angiogenesis in this disease, but also reveals a therapeutic opportunity for treatment of SONFH patients with demethylating agents.

Identification of aberrantly expressed of serum microRNAs in patients with hormone-induced non-traumatic osteonecrosis of the femoral head

Objective

The non-translation RNA-microRNA (miRNA) has been demonstrated to correlate to various disease occurrence in body. Serum miRNA was gradually considered as molecular markers for disease diagnosis. This study was designed to analyze differential serum miRNAs level in hormone-induced non-traumatic osteonecrosis of the femoral head (hormone-NOFH) patients.

Methods

We selected 30 patients with hormone-NOFH as case group, and 30 healthy volunteers were recruited as control group. miRCURYTM LNA miRNA chip and quantitative RT-PCR were used to examine differential miRNAs expression. Correlation assay was performed between miRNAs and NOFH trait.

Results

We found that 9 miRNAs were upregulated while 3 miRNAs were downregulated in hormone-TOFH patient serum by result of miRNA chip. QRT-PCR assay revealed that the level of miR-423-5p was significantly increased and miR-10a-5p was significantly decreased. Using Spearman correlation analysis, we observed that miR-423-5p serum level is positive association to FHC levels whereas miR-10a-5p has no association with FHC levels. Furthermore, miR-423-5p is negatively correlated to its downstream molecule-adiponectin.

Conclusion

We report a miRNA profile of hormone-NOFH and provide a new perspective to understand this intricate disease. This novel information suggests the potential roles of miR-423-5p in the diagnosis, prognosis biomarkers, or therapy targets of hormone-NOFH.