MicroRNAs are Critical Regulators of Osteoclast Differentiation

The miR-29-3p family suppresses inflammatory osteolysis

Osteoclasts are the cells primarily responsible for inflammation-induced bone loss, as is particularly seen in rheumatoid arthritis. Increasing evidence suggests that osteoclasts formed under homeostatic versus inflammatory conditions may differ in phenotype. While microRNA-29-3p family members (miR-29a-3p, miR-29b-3p, miR-29c-3p) promote the function of RANKL-induced osteoclasts, the role of miR-29-3p during inflammatory TNF-α-induced osteoclastogenesis is unknown. We used bulk RNA-seq, histology, qRT-PCR, reporter assays, and western blot analysis to examine bone marrow monocytic cell cultures and tissue from male mice in which the function of miR-29-3p family members was decreased by expression of a miR-29-3p tough decoy (TuD) competitive inhibitor in the myeloid lineage (LysM-cre). We found that RANKL-treated monocytic cells expressing the miR-29-3p TuD developed a hypercytokinemia/proinflammatory gene expression profile in vitro, which is associated with macrophages. These data support the concept that miR-29-3p suppresses macrophage lineage commitment and may have anti-inflammatory effects. In correlation, when miR-29-3p activity was decreased, TNF-α-induced osteoclast formation was accentuated in an in vivo model of localized osteolysis and in a cell-autonomous manner in vitro. Further, miR-29-3p targets mouse TNF receptor 1 (TNFR1/Tnfrsf1a), an evolutionarily conserved regulatory mechanism, which likely contributes to the increased TNF-α signaling sensitivity observed in the miR-29-3p decoy cells. Whereas our previous studies demonstrated that the miR-29-3p family promotes RANKL-induced bone resorption, the present work shows that miR-29-3p dampens TNF-α-induced osteoclastogenesis, indicating that miR-29-3p has pleiotropic effects in bone homeostasis and inflammatory osteolysis. Our data supports the concept that the knockdown of miR-29-3p activity could prime myeloid cells to respond to an inflammatory challenge and potentially shift lineage commitment toward macrophage, making the miR-29-3p family a potential therapeutic target for modulating inflammatory response.

Highlights on the Effects of Non-Coding RNAs in the Osteonecrosis of the Jaw

Osteonecrosis of the jaw is the progressive loss and destruction of bone affecting the maxilla or mandible in patients treated with antiresorptive and antiangiogenic agents without receiving prior radiation therapy. The pathogenesis involves the inflammatory pathway of receptor activator of nuclear factor NF-kB ligand and the macrophage colony-stimulating factor, essential for osteoclast precursors survival and proliferation and acting through its receptor c-Fms. Evidence has shown the role of non-coding RNAs in the pathogenesis of osteonecrosis of the jaw and this finding might be useful in diagnosis since these small RNAs could be considered as biomarkers of apoptotic activity in bone. Interestingly, it has been proved that miR-29 and miR-31-5p, acting on specific targets such as CALCR and RhoA, promote programmed-cell death and consequently the necrosis of bone tissue. Specific long non-coding RNAs, instead, have been detected both at reduced levels in patients with multiple myeloma and osteonecrosis, and associated with suppression of osteoblast differentiation, with consequences in the progression of mandible lesions. Among non-coding genic material, circular RNAs have the capability to modify the expression of specific mRNAs responsible for the inhibition of bisphosphonates activity on osteoclastogenesis.

Mesenchymal stem cell-derived apoptotic bodies alleviate alveolar bone destruction by regulating osteoclast differentiation and function

Periodontitis is caused by overactive osteoclast activity that results in the loss of periodontal supporting tissue and mesenchymal stem cells (MSCs) are essential for periodontal regeneration. However, the hypoxic periodontal microenvironment during periodontitis induces the apoptosis of MSCs. Apoptotic bodies (ABs) are the major product of apoptotic cells and have been attracting increased attention as potential mediators for periodontitis treatment, thus we investigated the effects of ABs derived from MSCs on periodontitis. MSCs were derived from bone marrows of mice and were cultured under hypoxic conditions for 72 h, after which ABs were isolated from the culture supernatant using a multi-filtration system. The results demonstrate that ABs derived from MSCs inhibited osteoclast differentiation and alveolar bone resorption. miRNA array analysis showed that miR-223-3p is highly enriched in those ABs and is critical for their therapeutic effects. Targetscan and luciferase activity results confirmed that Itgb1 is targeted by miR-223-3p, which interferes with the function of osteoclasts. Additionally, DC-STAMP is a key regulator that mediates membrane infusion. ABs and pre-osteoclasts expressed high levels of DC-STAMP on their membranes, which mediates the engulfment of ABs by pre-osteoclasts. ABs with knock-down of DC-STAMP failed to be engulfed by pre-osteoclasts. Collectively, MSC-derived ABs are targeted to be engulfed by pre-osteoclasts via DC-STAMP, which rescued alveolar bone loss by transferring miR-223-3p to osteoclasts, which in turn led to the attenuation of their differentiation and bone resorption. These results suggest that MSC-derived ABs are promising therapeutic agents for the treatment of periodontitis.

Circulating and extracellular vesicle-derived microRNAs as biomarkers in bone-related diseases

MicroRNAs (miRNA) are small non-coding RNA molecules that regulate posttranscriptional gene expression by repressing messengerRNA-targets. MiRNAs are abundant in many cell types and are secreted into extracellular fluids, protected from degradation by packaging in extracellular vesicles. These circulating miRNAs are easily accessible, disease-specific and sensitive to small changes, which makes them ideal biomarkers for diagnostic, prognostic, predictive or monitoring purposes. Specific miRNA signatures can be reflective of disease status and development or indicators of poor treatment response. This is especially important in malignant diseases, as the ease of accessibility of circulating miRNAs circumvents the need for invasive tissue biopsy. In osteogenesis, miRNAs can act either osteo-enhancing or osteo-repressing by targeting key transcription factors and signaling pathways. This review highlights the role of circulating and extracellular vesicle-derived miRNAs as biomarkers in bone-related diseases, with a specific focus on osteoporosis and osteosarcoma. To this end, a comprehensive literature search has been performed. The first part of the review discusses the history and biology of miRNAs, followed by a description of different types of biomarkers and an update of the current knowledge of miRNAs as biomarkers in bone related diseases. Finally, limitations of miRNAs biomarker research and future perspectives will be presented.

Identification of key genes and pathways in atherosclerosis using integrated bioinformatics analysis

BACKGROUND

Atherosclerosis (AS) is a chronic inflammatory disease that might induce severe cardiovascular events, such as myocardial infarction and cerebral infarction. These risk factors in the pathogenesis of AS remain uncertain and further research is needed. This study aims to explore the potential molecular mechanisms of AS by bioinformatics analyses.

METHODS

GSE100927 gene expression profiles, including 69 AS samples and 35 healthy controls, were downloaded from Gene Expression Omnibus database and indenfied for key genes and pathways in AS.

RESULTS

A total of 443 differentially expressed genes (DEGs) between control and AS were identified, including 323 down-regulated genes and 120 up-regulated genes. The Gene ontology terms enriched by the up-regulated DEGs were associated with the regulation of leukocyte activation, endocytic vesicle, and cytokine binding, while the down-regulated DEGs were associated with negative regulation of cell growth, extracellular matrix, and G protein-coupled receptor binding. KEGG pathway analysis showed that the up-regulated DEGs were enriched in Osteoclast differentiation and Phagosome, while the down-regulated DEGs were enriched in vascular smooth muscle contraction and cGMP-PKG signaling pathway. Using the modular analysis of Cytoscape, we identified 3 modules mainly involved in Leishmaniasis and Osteoclast differentiation. The GSEA analysis showed the up-regulated gene sets were enriched in the ribosome, ascorbated metabolism, and propanoate metabolism. The LASSO Cox regression analysis showed the top 3 genes were TNF, CX3CR1, and COL1R1. Finally, we found these immune cells were conferred significantly higher infiltrating density in the AS group.

CONCLUSIONS

Our data showed the pathway of Osteoclast differentiation and Leishmaniasis was involved in the AS process and we developed a three-gene model base on the prognosis of AS. These findings clarified the gene regulatory network of AS and may provide a novel target for AS therapy.

RANKL interferes with osteoclastogenesis in PEG-fused U937 cells through LGR4

INTRODUCTION

RANKL plays an important role in the differentiation and maturation process of preosteoclast cells. The osteoclast is a multinucleated cell that can have various sizes and a variable number of nuclei. However, there are no models that allow us to understand how successive cell fusions have a limit, or how cell fusion is regulated.

METHODOLOGY

The present investigation was aimed to determine whether fusing U937 cells with PEG to generate osteoclast-like cells expresses LGR4 and whether applying RANKL to these cells modifies osteoclastic activity compared to non-PEG-fused and RANKL-treated cells.

RESULTS

By fusing U937 cells with PEG, it was found that the LGR4 receptor expression was promoted as early as 24 hours of culture. Applying RANKL before or after fusion inhibits osteoclastic activity. Interfering RANKL interaction with LGR4 in PEG-treated cells recovers and increases cell fusion and osteoclastic activity. PEG-fused U937 cells show osteoclast markers similar to those observed in the classical RANKL-stimulated cell model.

CONCLUSION

Our model allows us to understand that RANKL has fusogenic activity during the first days of culture and in fused cells modulates fusion, contributing to differentiate the role of RANKL before and after fusion through LGR4.

Could BMPs Therapy Be Improved if BMPs Were Used in Composition Acting during Bone Formation in Endochondral Ossification?

The discovery of bone morphogenetic proteins (BMPs) inspired hope for the successful treatment of bone disorders, but side effects worsening the clinical effects were eventually observed. BMPs exert a synergistic effect, stimulating osteogenesis; however, predicting the best composition of growth factors for use in humans is difficult. Chondrocytes present within the growth plate produce growth factors stored in calcified cartilage adhering to metaphysis. These factors stimulate initial bone formation in metaphysis. We have previously determined the growth factors present in bovine calcified cartilage and produced by rat epiphyseal chondrocytes. The results suggest that growth factors stimulating physiological ossification are species dependent. The collection of human calcified cartilage for growth factors determination does not appear feasible, but chondrocytes for mRNA determination could be obtained. Their collection from young recipients, in view of the Academy of Medical Royal Colleges Recommendation, would be ethical. The authors of this review do not have facilities to conduct such a study and can only appeal to competent institutions to undertake the task. The results could help to formulate a better recipe for the stimulation of bone formation and improve clinical results.

The Functional Mechanism of MicroRNA in Oral Lichen Planus

Non-coding RNAs (ncRNAs) are transcribed from the genomes of mammals and other complex organisms, and many of them are alternately spliced and processed into smaller products. Types of ncRNAs include microRNAs (miRNAs), circular RNAs, and long ncRNAs. miRNAs are about 21 nucleotides long and form a broad class of post-transcriptional regulators of gene expression that affect numerous developmental and physiological processes in eukaryotes. They usually act as negative regulators of mRNA expression through complementary binding sequences in the 3’-UTR of the target mRNA, leading to translation inhibition and target degradation. In recent years, the importance of ncRNA in oral lichen planus (OLP), particularly miRNA, has attracted extensive attention. However, the biological functions of miRNAs and their mechanisms in OLP are still unclear. In this review, we discuss the role and function of miRNAs in OLP, and we also describe their potential functional roles as biomarkers for the diagnosis of OLP. MiRNAs are promising new therapeutic targets, but more work is needed to understand their biological functions.

Inhibition of miR-29 Activity in the Myeloid Lineage Increases Response to Calcitonin and Trabecular Bone Volume in Mice

The miR-29-3p family (miR-29a, miR-29b, miR-29c) of microRNAs is increased during receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis. In vivo, activation of a miR-29-3p tough decoy inhibitor in Cre recombinase under the control of the lysozyme 2 promoter-expressing cells (myeloid lineage) resulted in mice displaying enhanced trabecular and cortical bone volume because of decreased bone resorption. Calcitonin receptor (Calcr) is a miR-29 target that negatively regulates bone resorption. CALCR was significantly increased in RANKL-treated miR-29-decoy osteoclasts, and these cells were more responsive to the inhibitory effect of calcitonin on osteoclast formation. Further, cathepsin K (Ctsk), which is critical for resorption, was decreased in miR-29-decoy cells. CALCR is a Gs-coupled receptor and its activation raises cAMP levels. In turn, cAMP suppresses cathepsin K, and cAMP levels were increased in miR-29-decoy cells. siRNA-mediated knock-down of Calcr in miR-29 decoy osteoclasts allowed recovery of cathepsin K levels in these cells. Overall, using a novel knockin tough decoy mouse model, we identified a new role for miR-29-3p in bone homeostasis. In RANKL-driven osteoclastogenesis, as seen in normal bone remodeling, miR-29-3p promotes resorption. Consequently, inhibition of miR-29-3p activity in the myeloid lineage leads to increased trabecular and cortical bone. Further, this study documents an interrelationship between CALCR and CTSK in osteoclastic bone resorption, which is modulated by miR-29-3p.

miR-433-3p suppresses bone formation and mRNAs critical for osteoblast function in mice

MicroRNAs (miRNAs) are key posttranscriptional regulators of osteoblastic commitment and differentiation. miR-433-3p was previously shown to target Runt-related transcription factor 2 (Runx2) and to be repressed by bone morphogenetic protein (BMP) signaling. Here, we show that miR-433-3p is progressively decreased during osteoblastic differentiation of primary mouse bone marrow stromal cells in vitro, and we confirm its negative regulation of this process. Although repressors of osteoblastic differentiation often promote adipogenesis, inhibition of miR-433-3p did not affect adipocyte differentiation in vitro. Multiple pathways regulate osteogenesis. Using luciferase-3' untranslated region (UTR) reporter assays, five novel miR-433-3p targets involved in parathyroid hormone (PTH), mitogen-activated protein kinase (MAPK), Wnt, and glucocorticoid signaling pathways were validated. We show that Creb1 is a miR-433-3p target, and this transcription factor mediates key signaling downstream of PTH receptor activation. We also show that miR-433-3p targets hydroxysteroid 11-β dehydrogenase 1 (Hsd11b1), the enzyme that locally converts inactive glucocorticoids to their active form. miR-433-3p dampens glucocorticoid signaling, and targeting of Hsd11b1 could contribute to this phenomenon. Moreover, miR-433-3p targets R-spondin 3 (Rspo3), a leucine-rich repeat-containing G-protein coupled receptor (LGR) ligand that enhances Wnt signaling. Notably, Wnt canonical signaling is also blunted by miR-433-3p activity. In vivo, expression of a miR-433-3p inhibitor or tough decoy in the osteoblastic lineage increased trabecular bone volume. Mice expressing the miR-433-3p tough decoy displayed increased bone formation without alterations in osteoblast or osteoclast numbers or surface, indicating that miR-433-3p decreases osteoblast activity. Overall, we showed that miR-433-3p is a negative regulator of bone formation in vivo, targeting key bone-anabolic pathways including those involved in PTH signaling, Wnt, and endogenous glucocorticoids. Local delivery of miR-433-3p inhibitor could present a strategy for the management of bone loss disorders and bone defect repair. © 2021 American Society for Bone and Mineral Research (ASBMR).

Application of microRNA in Human Osteoporosis and Fragility Fracture: A Systemic Review of Literatures

MicroRNAs (miRNAs) could serve as ideal entry points to the deregulated pathways in osteoporosis due to their relatively simple upstream and downstream relationships with other molecules in the signaling cascades. Our study aimed to give a comprehensive review of the already identified miRNAs in osteoporosis from human blood samples and provide useful information for their clinical application. A systematic literature search for relevant studies was conducted in the Pubmed database from inception to December 2020. We set two essential inclusion criteria: human blood sampling and design of controlled studies. We sorted the results of analysis on human blood samples according to the study settings and compiled the most promising miRNAs with analyzed diagnostic values. Furthermore, in vitro and in vivo evidence for the mechanisms of the identified miRNAs was also illustrated. Based on both diagnostic value and evidence of mechanism from in vitro and in vivo experiments, miR-23b-3p, miR-140-3p, miR-300, miR-155-5p, miR-208a-3p, and miR-637 were preferred candidates in diagnostic panels and as therapeutic agents. Further studies are needed to build sound foundations for the clinical usage of miRNAs in osteoporosis.

miRNAs in osteoclast biology

MicroRNAs (miRNAs) are a class of short RNA molecules that mediate the regulation of gene activity through interactions with target mRNAs and subsequent silencing of gene expression. It has become increasingly clear the miRNAs regulate many diverse aspects of bone biology, including bone formation and bone resorption processes. The role of miRNAs specifically in osteoclasts has been of recent investigation, due to clinical interest in discovering new paradigms to control excessive bone resorption, as is observed in multiple conditions including aging, estrogen deprivation, cancer metastases or glucocorticoid use. Therefore understanding the role that miRNAs play during osteoclastic differentiation is of critical importance. In this review, we highlight and discuss general aspects of miRNA function in osteoclasts, including exciting data demonstrating that miRNAs encapsulated in extracellular vesicles (EVs) either originating from osteoclasts, or signaling to osteoclast from divergent sites, have important roles in bone homeostasis.

Inhibition of miR-29-3p isoforms via tough decoy suppresses osteoblast function in homeostasis but promotes intermittent parathyroid hormone-induced bone anabolism

miRNAs play a vital role in post-transcriptional regulation of gene expression in osteoblasts and osteoclasts, and the miR-29 family is expressed in both lineages. Using mice globally expressing a miR-29-3p tough decoy, we demonstrated a modest 30-60% decrease all three miR-29-3p isoforms: miR-29a, miR-29b, and miR-29c. While the miR-29-3p decoy did not impact osteoclast number or function, the tough decoy decreased bone formation in growing mice, which led to decreased trabecular bone volume in mature animals. These data support previous in vitro studies suggesting that miR-29-3p is a positive regulator of osteoblast differentiation. In contrast, when mice were treated with intermittent parathyroid hormone (PTH1-34), inhibition of miR-29-3p augmented the effect of PTH on cortical bone anabolism, increased bone formation rate and osteoblast surface, and increased levels of Ctnnb1/βcatenin mRNA, which is a miR-29 target. These findings highlight differences in the mechanisms controlling basal level bone formation and bone formation induced by intermittent PTH. Overall, the global miR-29-3p tough decoy model represents a modest loss-of-function, which could be a relevant tool for assessing the possible impact of systemically administered miR-29-3p inhibitors. Our studies provide a potential rationale for co-administration of PTH1-34 and miR-29-3p inhibitors, to boost bone formation in severely affected osteoporosis patients, particularly in the cortical compartment.

Roles of MicroRNAs in Bone Destruction of Rheumatoid Arthritis

As an important pathological result of rheumatoid arthritis (RA), bone destruction will lead to joint injury and dysfunction. The imbalance of bone metabolism caused by increased osteoclast activities and decreased osteoblast activities is the main cause of bone destruction in RA. MicroRNAs (MiRNAs) play an important role in regulating bone metabolic network. Recent studies have shown that miRNAs play indispensable roles in the occurrence and development of bone-related diseases including RA. In this paper, the role of miRNAs in regulating bone destruction of RA in recent years, especially the differentiation and activities of osteoclast and osteoblast, is reviewed. Our results will not only help provide ideas for further studies on miRNAs’ roles in regulating bone destruction, but give candidate targets for miRNAs-based drugs research in bone destruction therapy of RA as well.

Involvement of Noncoding RNAs in the Differentiation of Osteoclasts

As the most important bone-resorbing cells, osteoclasts play fundamental roles in bone remodeling and skeletal health. Much effort has been focused on identifying the regulators of osteoclast metabolism. Noncoding RNAs (ncRNAs) reportedly regulate osteoclast formation, differentiation, survival, and bone-resorbing activity to participate in bone physiology and pathology. The present review intends to provide a general framework for how ncRNAs and their targets regulate osteoclast differentiation and the important events of osteoclastogenesis they are involved in, including osteoclast precursor generation, early differentiation, mononuclear osteoclast fusion, and multinucleated osteoclast function and survival. This framework is beneficial for understanding bone biology and for identifying the potential biomarkers or therapeutic targets of bone diseases. The review also summarizes the results of in vivo experiments and classic experiment methods for osteoclast-related researches.

miR-346-3p promotes osteoclastogenesis via inhibiting TRAF3 gene

MicroRNAs (miRNAs) modulate gene expression and regulate many physiological and pathological conditions. However, their modulation and effect in osteoclastogenesis remain unknown. In this study, we investigated the role of miR-346-3p in regulating the osteoclast differentiation from RAW264.7 cells. We used the miRNA microarray assay, miR-346-3p mimic transfection, tartrate resistant acid phosphatase (TRAP) staining, bone resorption assay, qRT-PCR, and western blot. Our results showed that the expression of miR-346-3p was significantly upregulated during osteoclast differentiation. Further, by transfecting cells with miR-346-3p mimic, we observed an increased number of TRAP-positive multinucleated cells, increased pit area caused by bone resorption, and enhanced expression of osteoclast-specific genes and proteins. Conversely, miR-346-3p inhibition attenuated the osteoclast differentiation and function. Software-mediated prediction and validation using luciferase reporter assay showed that TRAF3, a negative regulator of osteoclast differentiation, was inhibited by miR-346-3p overexpression. Our results showed that miR-346-3p directly targeted TRAF3 mRNA via binding to its 3'-UTR and inhibited the expression of TRAF3 protein. Taken together, our results revealed that miR-346-3p promotes the regulation of osteoclastogenesis by suppressing the TRAF3 gene. In conclusion, miR-346-3p could be a novel therapeutic target for bone loss-related pathogenesis.

Overexpression of microRNA-96 is associated with poor prognosis and promotes proliferation, migration and invasion in cholangiocarcinoma cells via MTSS1

MicroRNA-96 (miR-96) has been revealed serve an oncogenic role in various types of cancer. However, the role of miR-96 in cholangiocarcinoma (CCA) development and progression is yet to be elucidated. Thus, the aim of the present study was to investigate the role of miR-96 in CCA. The expression pattern of miR-96 in CCA tissues and cell lines was evaluated using reverse transcription-quantitative PCR analysis. Kaplan-Meier curves and Cox regression analyses were conducted to investigate the prognostic significance of miR-96 in CCA. Cell Counting Kit-8 and Transwell assays were performed to identify the functions of miR-96. The association between miR-96 and metastasis suppressor-1 (MTSS1) was verified using a dual-luciferase assay. The results demonstrated that miR-96 expression levels were increased in CCA tissues and cell lines compared with those in adjacent normal tissues and normal human intrahepatic biliary epithelial cell lines, respectively. High expression levels of miR-96 were significantly associated with lymph node metastasis, differentiation and TNM stage. In addition, upregulated expression of miR-96 was associated with a poorer prognosis and was predicted to be a prognostic factor in patients with CCA. Overexpression of miR-96 in vitro promoted CCA cell proliferation, migration and invasion. Additionally, MTSS1 was identified as a direct target of miR-96. The results of the present study indicated the clinical and biological importance of miR-96 as an oncogene in CCA. miR-96 may represent an independent prognostic biomarker and may promote CCA cell proliferation, migration and invasion by targeting MTSS1.

Lung Cancer Cells Derived Circulating miR-21 Promotes Differentiation of Monocytes into Osteoclasts

Objective

Osteoclastogenesis is a key process in osteolytic bone metastasis (BM). Previous studies indicated that some miRNAs could regulate cancers progression and osteoclastogenesis. Our purpose was to investigate the roles of lung cancer cells-derived circulating miR-21 on osteoclastogenesis and its clinical significance in BM patients.

Materials and Methods

The difference of miRNA expression in two lung cancer cell lines SBC-5 (with characteristic BM ability) and SBC-3 (without BM ability) were analyzed by microarray and qRT-PCR. Circulating miR-21 levels of lung cancer patients with or without BM were compared by qRT-PCR. The TRAP staining was used to investigate the effects of conditioned media from lung cancer cell lines or patients’ plasma with different miR-21 levels on osteoclastogenesis. ROC curve was used to evaluate the diagnostic performance of circulating miR-21 in BM patients.

Results

We found that miR-21 expression was specifically higher in SBC-5 than that in SBC-3 cells. The supernatants of SBC-5 cells with higher-level miR-21 promoted osteoclastogenesis. Moreover, we demonstrated that the circulating miR-21 level was significantly higher in BM patients than that in non-BM patients. The plasma from BM patients with higher-level miR-21 could also promote osteoclastogenesis. Mechanistically, lung cancer cells-derived circulating miR-21 could be transferred into osteoclast precursor cells and promote osteoclastogenesis probably by inhibiting PTEN. Finally, clinical data showed that circulating miR-21 had a potential for the diagnosis of BM.

Conclusion

Overall, our findings suggested that circulating miR-21 played important roles in osteoclastogenesis of lung cancer patients and may serve as a biomarker to diagnose BM of lung cancer.

Scaffold-Based Gene Therapeutics for Osteochondral Tissue Engineering

Significant progress in osteochondral tissue engineering has been made for biomaterials designed to deliver growth factors that promote tissue regeneration. However, due to diffusion characteristics of hydrogels, the accurate delivery of signaling molecules remains a challenge. In comparison to the direct delivery of growth factors, gene therapy can overcome these challenges by allowing the simultaneous delivery of growth factors and transcription factors, thereby enhancing the multifactorial processes of tissue formation. Scaffold-based gene therapy provides a promising approach for tissue engineering through transfecting cells to enhance the sustained expression of the protein of interest or through silencing target genes associated with bone and joint disease. Reports of the efficacy of gene therapy to regenerate bone/cartilage tissue regeneration are widespread, but reviews on osteochondral tissue engineering using scaffold-based gene therapy are sparse. Herein, we review the recent advances in gene therapy with a focus on tissue engineering scaffolds for osteochondral regeneration.

MiRNA-483-5p is involved in the pathogenesis of osteoporosis by promoting osteoclast differentiation

AIMS

The study aimed to investigate the roles of miR-483-5p and IGF2 in osteoclast formation.

METHODS

Blood and bone tissues were collected from osteoporosis and non-osteoporosis patients with hip fractures for gene expression analysis. CD14 + peripheral blood mononuclear cells (PBMCs) were isolated for differentiating osteoclasts. MiR-483-5p mimic and inhibitor was transfected into CD14 + PBMCs, respectively. Predicted by TargetScan and verified by Dual-luciferase reporter assay system, insulin-like growth factor-2 (IGF2) could be targeted by miR-483-5p. IGF2 expression vector was co-transfected with miR-483-5p mimic to study the role of IGF2 in miR-483-5p affecting osteoclast differentiation. Flow cytometry was performed for cell apoptosis analysis.

RESULTS

High-expressed miR-483-5p and low-expressed IGF2 were frequently found in the serums and bone tissues derived from osteoporotic patients. We found that up-regulation of miR-483-5p in CD14 + PBMCs notably increased the number of TRAP-positive cells, at the same time, the expression levels of TRAP, nuclear factor of activated T-cells (NFATc1), cytoplasmic 1 (NFAT2) and Cathepsin K (CTSK) were also up-regulated. However, overexpressed IGF2 effectively reversed such effects produced by up-regulation of miR-483-5p on osteoclastogenesis-related factors in CD14 + PBMCs. Moreover, forced expression of IGF2 could also enhance apoptosis of osteoclasts reduced by miR-483-5p.

CONCLUSIONS

Our study suggests that miRNA-483-5p is involved in the pathogenesis of osteoporosis by promoting osteoclast differentiation.