Genome-wide microRNA screening reveals miR-582-5p as a mesenchymal stem cell-specific microRNA in subchondral bone of the human knee joint

Unraveling the molecular landscape of osteoarthritis: A comprehensive review focused on the role of non-coding RNAs

Osteoarthritis (OA) poses a significant global health challenge, with its prevalence anticipated to increase in the coming years. This review delves into the emerging molecular biomarkers in OA pathology, focusing on the roles of various molecules such as metabolites, noncoding RNAs (ncRNAs), including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Advances in omics technologies have transformed biomarker identification, enabling comprehensive analyses of the complex pathways involved in OA pathogenesis. Notably, ncRNAs, especially miRNAs and lncRNAs, exhibit dysregulated expression patterns in OA, presenting promising opportunities for diagnosis and therapy. Additionally, the intricate interplay between epigenetic modifications and OA progression highlights the regulatory role of epigenetics in gene expression dynamics. Genome-wide association studies have pinpointed key genes undergoing epigenetic changes, providing insights into the inflammatory processes and chondrocyte hypertrophy typical of OA. Understanding the molecular landscape of OA, including biomarkers and epigenetic mechanisms, holds significant potential for developing innovative diagnostic tools and therapeutic strategies for OA management.

Global burden and socioeconomic impact of knee osteoarthritis: a comprehensive analysis

Objective

To report the trend changes of the prevalence, incidence, and disability-adjusted life years (DALYs) of knee osteoarthritis (KOA) according to age, sex, sociodemographic index (SDI), and income.

Methods

This analysis used estimates from the broader Global Burden of Disease (GBD) study 2019, which covered 201 countries from 1990 to 2019. National prevalence, incidence, and DALYs were shown by using ggplot2 and maps packages. Five-year intervals were used for age groupings. The Commonwealth and the World Bank income classifications were used for income grouping.

Results

Globally, there were ~364.58 million prevalent cases (females: 225.16 million), 29.51 million incident cases (females: 17.53 million), and 11.53 million DALYs (females: 7.09 million) due to KOA in 2019. The Western Pacific Region had a high endemicity of ~7,319.87 cases per 100,000 people (7.64%). Japan's prevalence rate (12,610.12 cases per 100,000 population) was 10 times that of Somalia (1,178.23) in 2019. In 200 countries (except the United Arab Emirates), the prevalence, incidence, and DALY rates of KOA in 2019 were higher among females than among males and increased with age up to the oldest age group. The prevalence was highest in the high-middle SDI countries, and the incidence and DALYs were highest in the middle SDI countries.

Conclusion

There was a large burden of KOA worldwide, with some notable intercountry variation. Some countries had 10 times the burden of other countries. Increasing population awareness regarding the prevalence, incidence, and DALYs of KOA with a focus on the population in the Western Pacific Region is needed, particularly for older females. informs health policy development, and contributes to improving the efficiency, equity, and effectiveness of healthcare systems.

Comprehensive analysis on subchondral bone marrow lesions of human osteoarthritis by integrating bulk and single-cell transcriptomes

OBJECTIVE

This study aims to demonstrate the cellular composition and underlying mechanisms in subchondral bone marrow lesions (BMLs) of knee osteoarthritis (OA).

METHODS

BMLs were assessed by MRI Osteoarthritis Knee Score (MOAKS)≥2. Bulk RNA-sequencing (bulk-seq) and BML-specific differentially expressed genes (DEGs) analysis were performed among subchondral bone samples (including OA-BML=3, paired OA-NBML=3; non-OA=3). The hub genes of BMLs were identified by verifying in independent datasets and multiple bioinformatic analyses. To further estimate cell-type composition of subchondral bone, we utilized two newly developed deconvolution algorithms (MuSiC, MCP-counter) in transcriptomic datasets, based on signatures from open-accessed single-cell RNA sequencing (scRNA-seq). Finally, competing endogenous RNA (ceRNA) and transcription factor (TF) networks were constructed through multiple predictive databases, and validated by public non-coding RNA profiles.

RESULTS

A total of 86 BML-specific DEGs (up 79, down 7) were identified. IL11 and VCAN were identified as core hub genes. The "has-miR-424-5p/lncRNA PVT1" was determined as crucial network, targeting IL11 and VCAN, respectively. More importantly, two deconvolution algorithms produced approximate estimations of cell-type composition, and the cluster of heterotopic-chondrocyte was discovered abundant in BMLs, and positively correlated with the expression of hub genes.

CONCLUSION

IL11 and VCAN were identified as the core hub genes of BMLs, and their molecular networks were determined as well. We profiled the characteristics of subchondral bone at single-cell level and determined that the heterotopic-chondrocyte was abundant in BMLs and was closely linked to IL11 and VCAN. Our study may provide new insights into the microenvironment and pathological molecular mechanism of BMLs, and could lead to novel therapeutic strategies.

Emerging molecular biomarkers in osteoarthritis pathology

Osteoarthritis (OA) is the most common form of arthritis resulting in joint discomfort and disability, culminating in decline in life quality. Attention has been drawn in recent years to disease-associated molecular biomarkers found in readily accessible biofluids due to low invasiveness of acquisition and their potential to detect early pathological molecular changes not observed with traditional imaging methodology. These biochemical markers of OA have been found in synovial fluid, blood, and urine. They include emerging molecular classes, such as metabolites and noncoding RNAs, as well as classical biomarkers, like inflammatory mediators and by-products of degradative processes involving articular cartilage. Although blood-based biomarkers tend to be most studied, the use of synovial fluid, a more isolated biofluid in the synovial joint, and urine as an excreted fluid containing OA biomarkers can offer valuable information on local and overall disease activity, respectively. Furthermore, larger clinical studies are required to determine relationships between biomarkers in different biofluids, and their impacts on patient measures of OA. This narrative review provides a concise overview of recent studies of OA using these four classes of biomarkers as potential biomarker for measuring disease incidence, staging, prognosis, and therapeutic intervention efficacy.

Comparison between articular chondrocytes and mesenchymal stromal cells for the production of articular cartilage implants

Focal lesions of articular cartilage give rise to pain and reduced joint function and may, if left untreated, lead to osteoarthritis. Implantation of in vitro generated, scaffold-free autologous cartilage discs may represent the best treatment option. Here we compare articular chondrocytes (ACs) and bone marrow-derived mesenchymal stromal cells (MSCs) for their ability to make scaffold-free cartilage discs. Articular chondrocytes produced more extracellular matrix per seeded cell than mesenchymal stromal cells. Quantitative proteomics analysis showed that articular chondrocyte discs contained more articular cartilage proteins, while mesenchymal stromal cell discs had more proteins associated with cartilage hypertrophy and bone formation. Sequencing analysis revealed more microRNAs associated with normal cartilage in articular chondrocyte discs, and large-scale target predictions, performed for the first time for in vitro chondrogenesis, suggested that differential expression of microRNAs in the two disc types were important mechanisms behind differential synthesis of proteins. We conclude that articular chondrocytes should be preferred over mesenchymal stromal cells for tissue engineering of articular cartilage.

Application and Molecular Mechanisms of Extracellular Vesicles Derived from Mesenchymal Stem Cells in Osteoporosis

Osteoporosis (OP) is a chronic bone disease characterized by decreased bone mass, destroyed bone microstructure, and increased bone fragility. Accumulative evidence shows that extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) (MSC-EVs), especially exosomes (Exos), exhibit great potential in the treatment of OP. However, the research on MSC-EVs in the treatment of OP is still in the initial stage. The potential mechanism has not been fully clarified. Therefore, by reviewing the relevant literature of MSC-EVs and OP in recent years, we summarized the latest application of bone targeted MSC-EVs in the treatment of OP and further elaborated the potential mechanism of MSC-EVs in regulating bone formation, bone resorption, bone angiogenesis, and immune regulation through internal bioactive molecules to alleviate OP, providing a theoretical basis for the related research of MSC-EVs in the treatment of OP.

Regulatory of miRNAs in tri-lineage differentiation of C3H10T1/2

MicroRNAs (miRNAs) are non-coding single-stranded RNA molecules encoded by endogenous genes, which play a vital role in cell generation, metabolism, apoptosis and stem cell differentiation. C3H10T1/2, a mesenchymal cell extracted from mouse embryos, is capable of osteogenic differentiation, adipogenic differentiation and chondrogenic differentiation. Extensive studies have shown that not only miRNAs can directly trigger targeted genes to regulate the tri-lineage differentiation of C3H10T1/2, but it also can indirectly regulate the differentiation by triggering different signaling pathways or various downstream molecules. This paper aims to clarify the regulatory roles of different miRNAs on C3H10T1/2 differentiation, and discussing their balance effect among osteogenic differentiation, adipogenic differentiation and chondrogenic differentiation of C3H10T1/2. We also review the biogenesis of miRNAs, Wnt signaling pathways, MAPK signaling pathways and BMP signaling pathways and provide some specific examples of how these signaling pathways act on C3H10T1/2 tri-lineage differentiation. On this basis, we hope that a deeper understanding of the differentiation and regulation mechanism of miRNAs in C3H10T1/2 can provide a promising therapeutic method for the clinical treatment of bone defects, osteoporosis, osteoarthritis and other diseases.

Recent Advances in Pharmacological Intervention of Osteoarthritis: A Biological Aspect

Osteoarthritis (OA) is a degenerative joint disease in the musculoskeletal system with a relatively high incidence and disability rate in the elderly. It is characterized by the degradation of articular cartilage, inflammation of the synovial membrane, and abnormal structure in the periarticular and subchondral bones. Although progress has been made in uncovering the molecular mechanism, the etiology of OA is still complicated and unclear. Nevertheless, there is no treatment method that can effectively prevent or reverse the deterioration of cartilage and bone structure. In recent years, in the field of pharmacology, research focus has shifted to disease prevention and early treatment rather than disease modification in OA. Biologic agents become more and more attractive as their direct or indirect intervention effects on the initiation or development of OA. In this review, we will discuss a wide spectrum of biologic agents ranging from DNA, noncoding RNA, exosome, platelet-rich plasma (PRP), to protein. We searched for key words such as OA, DNA, gene, RNA, exosome, PRP, protein, and so on. From the pharmacological aspect, stem cell therapy is a very special technique, which is not included in this review. The literatures ranging from January 2016 to August 2021 were included and summarized. In this review, we aim to help readers have a complete and precise understanding of the current pharmacological research progress in the intervention of OA from the biological aspect and provide an indication for the future translational studies.

Microarray analysis of long non-coding RNAs related to osteogenic differentiation of human dental pulp stem cells

Background/purpose

Dental pulp stem cells (DPSCs) are candidate seed cells for bone tissue engineering, but the molecular regulation of osteogenic differentiation in DPSCs is not fully understood. Long non-coding RNAs (lncRNAs) are important regulators of gene expression, and whether they play roles in osteogenic differentiation of DPSCs requires more study.

Materials and methods

DPSCs were isolated and cultured. The mRNA and lncRNA expression profiles were compared through microarray assay between osteo-differentiated DPSCs and non-differentiated DPSCs. Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, Gene ontology (GO) analyses, and the mRNA-lncRNA co-expression analyses were performed for functional annotation of differentially expressed RNAs. Small interfering RNA (siRNA) was used to interfere the expression of lncRNA ENST00000533992 (also named smooth muscle-induced lncRNA or SMILR), a candidate regulator, then the osteogenic differentiation potential of DPSCs was analyzed.

Results

DPSCs were isolated and cultured successfully. The expression of 273 mRNAs and 184 lncRNAs changed significantly in DPSCs after osteogenic induction. KEGG analyses and GO analyses showed that the differentially expressed RNAs were enriched in several pathways and biological processes. The mRNA-lncRNA co-expression network was constructed to reveal the potential relationships between mRNAs and lncRNAs. The osteogenic differentiation potential of DPSCs decreased when SMILR was interfered.

Conclusion

The present study provides clues for seeking for lncRNAs that participate in the regulation of osteogenic differentiation in DPSCs. LncRNA SMILR could play a role in regulating osteogenic differentiation of DPSCs.

Osteoporosis, fracture, osteoarthritis & sarcopenia: A systematic review of circulating microRNA association

Circulating microRNAs (c-miRs) show promise as biomarkers. This systematic review explores their potential association with age-related fracture/osteoporosis (OP), osteoarthritis (OA) and sarcopenia (SP), as well as cross-disease association. Most overlap occurred between OA and OP, suggesting potentially shared microRNA activity. There was little agreement in results across studies. Few reported receiver operating characteristic analysis (ROC) and many identified significant dysregulation in disease, but direction of effect was commonly conflicting. c-miRs with most evidence for consistency in dysregulation included miR-146a, miR-155 and miR-98 for OA (upregulated). Area under the curve (AUC) for miR-146a biomarker performance was AUC 0.92, p = 0.028. miR-125b (AUC 0.76-0.89), miR-100, miR-148a and miR-24 were consistently upregulated in OP. Insufficient evidence exists for c-miRs in SP. Study quality was typically rated intermediate/high risk of bias. Wide study heterogeneity meant meta-analysis was not possible. We provide detailed critique and recommendations for future approaches in c-miR analyses based on this review.

The non-coding RNA interactome in joint health and disease

Non-coding RNAs have distinct regulatory roles in the pathogenesis of joint diseases including osteoarthritis (OA) and rheumatoid arthritis (RA). As the amount of high-throughput profiling studies and mechanistic investigations of microRNAs, long non-coding RNAs and circular RNAs in joint tissues and biofluids has increased, data have emerged that suggest complex interactions among non-coding RNAs that are often overlooked as critical regulators of gene expression. Identifying these non-coding RNAs and their interactions is useful for understanding both joint health and disease. Non-coding RNAs regulate signalling pathways and biological processes that are important for normal joint development but, when dysregulated, can contribute to disease. The specific expression profiles of non-coding RNAs in various disease states support their roles as promising candidate biomarkers, mediators of pathogenic mechanisms and potential therapeutic targets. This Review synthesizes literature published in the past 2 years on the role of non-coding RNAs in OA and RA with a focus on inflammation, cell death, cell proliferation and extracellular matrix dysregulation. Research to date makes it apparent that 'non-coding' does not mean 'non-essential' and that non-coding RNAs are important parts of a complex interactome that underlies OA and RA.

miR-424-5p shuttled by bone marrow stem cells-derived exosomes attenuates osteogenesis via regulating WIF1-mediated Wnt/β-catenin axis

Emerging evidence proves that exosomes contain specific microRNAs(miRNAs) contribute to osteogenic differentiation of bone marrow stem cells (BMSCs). However, the role and mechanism of bone marrow stem cells (BMSCs)-derived exosomes overexpressing miR-424-5p in osteoblasts remains unclear. Firstly, the BMSCs-derived exosomes were isolated, and identified by Western blot with the exosome surface markers CD9, CD81 and CD63. Quantitative real-time polymerase chain reaction (qRT-PCR) was applied to detect the level of miR-424-5p in exosomes, and western blot was implemented to verify the WIF1/Wnt/β-catenin expression. The binding association between miR-424-5p and WIF1 was determined by the dual-luciferase reporter gene assay. Functional enhancement experiments were adopted to determine the role of exosome-carried miR-424-5p and WIF1/Wnt/β-catenin in osteogenic differentiation. ALP staining was adopted, and levels of RUNX2, OCN, and OPN were monitored using qRT-PCR to determine osteogenic differentiation. As a result, In vivo experiments showed that RUNX2, OCN and OPN levels decreased and the ALP activity was dampened after miR-424-5p overexpression in exosomes. Besides, exosomes overexpressing miR-424-5p attenuated osteogenic development via WIF1/Wnt/β-catenin. Our findings may bring evidence for miR-424-5p as a new biomarker for the treatment of osteoporosis.

MicroRNAs as Important Regulators Mediate the Multiple Differentiation of Mesenchymal Stromal Cells

MicroRNAs (miRNAs) are endogenous short non-encoding RNAs which play a critical role on the output of the proteins, and influence multiple biological characteristics of the cells and physiological processes in the body. Mesenchymal stem/stromal cells (MSCs) are adult multipotent stem cells and characterized by self-renewal and multidifferentiation and have been widely used for disease treatment and regenerative medicine. Meanwhile, MSCs play a critical role in maintaining homeostasis in the body, and dysfunction of MSC differentiation leads to many diseases. The differentiation of MSCs is a complex physiological process and is the result of programmed expression of a series of genes. It has been extensively proven that the differentiation process or programmed gene expression is also regulated accurately by miRNAs. The differentiation of MSCs regulated by miRNAs is also a complex, interdependent, and dynamic process, and a full understanding of the role of miRNAs will provide clues on the appropriate upregulation or downregulation of corresponding miRNAs to mediate the differentiation efficiency. This review summarizes the roles and associated signaling pathways of miRNAs in adipogenesis, chondrogenesis, and osteogenesis of MSCs, which may provide new hints on MSCs or miRNAs as therapeutic strategies for regenerative medicine and biotherapy for related diseases.

Diagnostic Performance of a Panel of miRNAs (OsteomiR) for Osteoporosis in a Cohort of Postmenopausal Women

A specific signature of 19 circulating miRNAs (osteomiRs) has been reported to be associated with fragility fractures due to postmenopausal osteoporosis. However, it is unknown whether osteoporotic fractures or low BMD phenotypes are independently contributing to changes in osteomiR serum levels. The first aim was to characterize the abundance, sensitivity to hemolysis, and correlation of osteomiR serum levels, the second objective to evaluate the diagnostic accuracy of osteomiRs for osteoporosis according to the WHO criteria and on basis of major osteoporotic fracture history. Fifty postmenopausal women with osteoporosis (with or without fragility fracture) and 50 non-osteoporotic women were included in this cross-sectional study. The diagnostic performance of osteomiRs for osteoporosis based on the WHO definition or fracture history was evaluated using multiple logistic regression and receiver-operator curve (AUC) analysis. The osteomiR® signature is composed of four clusters of miRNAs providing good performance for the diagnosis of osteoporosis in postmenopausal women defined by WHO criteria (AUC = 0.830) and based on history of major osteoporotic fractures (AUC = 0.834). The classification performance for the WHO criteria and for fracture risk is driven by miR-375 and miR-203a, respectively. OsteomiRs, a signature of 19 emerging miRNA bone biomarkers, are measurable in human serum samples. They constitute a panel of independent bone and muscle biomarkers, which in combination could serve as diagnostic biomarkers for osteoporosis in postmenopausal women.

Osteoarthritis year in review: genetics, genomics, epigenetics

OBJECTIVE

In this review, we have highlighted advances in genetics, genomics and epigenetics in the field of osteoarthritis (OA) over the past year.

METHODS

A literature search was performed using PubMed and the criteria: "osteoarthritis" and one of the following terms "genetic(s), genomic(s), epigenetic(s), epigenomic(s), noncoding RNA, microRNA, long noncoding RNA, lncRNA, circular RNA, RNA sequencing, single cell sequencing, or DNA methylation between April 1, 2019 and April 30, 2020.

RESULTS

We identified 653 unique publications, many studies spanned multiple search terms. We summarized advances relating to evolutionary genetics, pain, ethnicity specific risk factors, functional studies of gene variants, and interactions between coding and non-coding RNAs in OA pathogenesis.

CONCLUSIONS

Studies have identified variants contributing to OA susceptibility, candidate biomarkers for diagnosis and prognosis, as well as promising therapeutic candidates. Validation in multiple cohorts, multi-omics strategies, and machine learning aided computational analyses have all contributed to the strength of published literature. Open access data-sets, greater sample sizes to capture broader populations and understanding disease mechanisms by investigating the interactions between multiple tissue types will further aid in progress towards understanding and curing OA.

Polysaccharide from Angelica sinensis attenuates SNP-induced apoptosis in osteoarthritis chondrocytes by inducing autophagy via the ERK1/2 pathway

OBJECTIVE

Chondrocyte apoptosis plays a vital role in osteoarthritis (OA) progression. Angelica sinensis polysaccharide (ASP), a traditional Chinese medicine, possesses anti-inflammatory and anti-apoptotic properties in chondrocytes. This study aimed to determine the protective role of ASP on sodium nitroprusside (SNP)-induced chondrocyte apoptosis, and explore the underlying mechanism.

METHOD

Human primary chondrocytes isolated from the articular cartilage of OA patients were treated with SNP alone or in combination with different doses of ASP. Cell viability and apoptosis were assessed, and apoptosis-related proteins including Bcl-2 and Bax were detected. Autophagy levels were evaluated by light chain 3 (LC3) II immunofluorescence staining, mRFP-GFP-LC3 fluorescence localization, and western blot (LC3II, p62, Beclin-1, Atg5). Meanwhile, activation of the ERK 1/2 pathway was determined by western blot. The autophagy inhibitors, 3-methyladenine (3-MA), chloroquine (CQ), and a specific inhibitor of ERK1/2, SCH772984, were used to confirm the autophagic effect of ASP.

RESULTS

The results showed that SNP-induced chondrocyte apoptosis was significantly rescued by ASP, whereas ASP alone promoted chondrocyte proliferation. The anti-apoptotic effect of ASP was related to the enhanced autophagy and depended on the activation of the ERK1/2 pathway.

CONCLUSION

ASP markedly rescued SNP-induced apoptosis by activating ERK1/2-dependent autophagy in chondrocytes, and it made ASP as a potential therapeutic supplementation for OA treatment.

Characterization of primary cilia features reveal cell-type specific variability in in vitro models of osteogenic and chondrogenic differentiation

Primary cilia are non-motile sensory antennae present on most vertebrate cell surfaces. They serve to transduce and integrate diverse external stimuli into functional cellular responses vital for development, differentiation and homeostasis. Ciliary characteristics, such as length, structure and frequency are often tailored to distinct differentiated cell states. Primary cilia are present on a variety of skeletal cell-types and facilitate the assimilation of sensory cues to direct skeletal development and repair. However, there is limited knowledge of ciliary variation in response to the activation of distinct differentiation cascades in different skeletal cell-types. C3H10T1/2, MC3T3-E1 and ATDC5 cells are mesenchymal stem cells, preosteoblast and prechondrocyte cell-lines, respectively. They are commonly employed in numerous in vitro studies, investigating the molecular mechanisms underlying osteoblast and chondrocyte differentiation, skeletal disease and repair. Here we sought to evaluate the primary cilia length and frequencies during osteogenic differentiation in C3H10T1/2 and MC3T3-E1 and chondrogenic differentiation in ATDC5 cells, over a period of 21 days. Our data inform on the presence of stable cilia to orchestrate signaling and dynamic alterations in their features during extended periods of differentiation. Taken together with existing literature these findings reflect the occurrence of not only lineage but cell-type specific variation in ciliary attributes during differentiation. These results extend our current knowledge, shining light on the variabilities in primary cilia features correlated with distinct differentiated cell phenotypes. It may have broader implications in studies using these cell-lines to explore cilia dependent cellular processes and treatment modalities for skeletal disorders centered on cilia modulation.

MicroRNA-29b Promotes Subchondral Bone Loss in TMJ Osteoarthritis

Abnormal subchondral bone remodeling plays important roles during osteoarthritis (OA) pathology. Recent studies show that bone marrow mesenchymal stem cells (BMSCs) in osteoarthritic subchondral bones exhibit a prominent pro-osteoclastic effect that contributes to abnormal subchondral bone remodeling; however, the pathologic mechanism remains unclear. In the present study, we used a mouse model with OA-like change in the temporomandibular joint (TMJ) induced by an experimentally unilateral anterior crossbite (UAC) and found that the level of microRNA-29b (miR-29b), but not miR-29a or miR-29c, was markedly lower in BMSCs from subchondral bones of UAC mice as compared with that from the sham control mice. With an intra-articular aptamer delivery system, BMSC-specific overexpression of miR-29b by aptamer-agomiR-29b rescued subchondral bone loss and osteoclast hyperfunction in UAC mice, as demonstrated by a significant increase in bone mineral density, bone volume fraction, trabecular thickness, and the gene expression of osteocalcin and Runx2 but decreased trabecular separation, osteoclast number and osteoclast surface/bone surface, and the gene expression of cathepsin K, Trap, Wnt5a, Rankl, and Rank as compared with those in the UAC mice treated by aptamer-NC (all P < 0.05). In addition, BMSC-specific inhibition of miR-29b by aptamer-antagomiR-29b exacerbated those responses in UAC mice. Notably, although it primarily affected miR-29b levels in the subchondral bone (but not in cartilage and synovium), BMSC-specific overexpression of miR-29b in UAC mice largely rescued OA-like cartilage degradation, including decreased chondrocyte density, cartilage thickness, and the percentage areas of proteoglycans and type II collagen, while BMSC-specific inhibition of miR-29b aggravated these characteristics of cartilage degradation in UAC mice. Moreover, we identified Wnt5a, but not Rankl or Sdf-1, as the direct target of miR-29b. The results of the present study indicate that miR-29b is a key regulator of the pro-osteoclastic effects of BMSCs in TMJ-OA subchondral bones and plays important roles in the TMJ-OA progression.

Role of MicroRNA, LncRNA, and Exosomes in the Progression of Osteoarthritis: A Review of Recent Literature

Osteoarthritis (OA) is a common clinical degenerative disease characterized by the destruction of articular cartilage, which has an increasing impact on people's lives and social economy. The pathogenesis of OA is complex and unclear, and there is no effective way to block its progress. The study of the pathogenesis of OA is the prerequisite for the early diagnosis and effective treatment of OA. To define the pathogenesis of OA, this review considers the pathological mechanism of OA that involves microRNA, lncRNA, and exosomes. More and more evidence shows that microRNA, lncRNA, and exosomes are closely related to OA. MicroRNA inhibits the target gene by binding to the 3'- untranslated region of the targets. LncRNA usually competes with microRNA to regulate the expression level of downstream genes, while exosomes, as a carrier of intercellular information transfer, transmit the biological information of mother cells to target cells, and the effect of exosomes secreted by different cells on OA are different. In this review, we emphasized that different microRNA, lncRNA, and exosomes have different regulatory effects on chondrocyte proliferation and apoptosis, extracellular matrix degradation and inflammation. Besides, we classified and analyzed these molecules according to their effects on the progress of OA. Based on the analysis of the reported literature, this review reveals some pathogenesis of OA, and emphasizes that microRNA, lncRNA, and exosomes have great potential to assist early diagnosis and effective treatment of OA.

5-Hydroxy-l-tryptophan Promotes the Milk Calcium Level via the miR-99a-3p/ATP2B1 Axis in Goat Mammary Epithelial Cells

5-Hydroxy-l-tryptophan (5-HTP) is the primary product that converts l-tryptophan into 5-hydroxytryptamine by a rate-limiting enzyme. Our previous study found that 5-HTP could promote the intracellular calcium level in goat mammary epithelial cells (GMECs). Herein, first, dairy goats were injected with 5-HTP or saline daily from 7 days before delivery, and the calcium level in colostrum of 5-HTP-injected goats was significantly higher than that of saline-injected goats. Moreover, miR-99a-3p expression was significantly increased after 5-HTP treatment from transcriptome sequencing analysis and quantitative real-time polymerase chain reaction. In addition, it was found that ATP2B1 is one of the target genes of miR-99a-3p predicted by bioinformatic methods, which plays a crucial role in the maintenance of intracellular calcium homeostasis of mammary epithelial cells. Next, we confirmed that miR-99a-3p could increase the intracellular calcium level via decreasing ATP2B1 in GMECs. Taken together, we draw the conclusion that 5-HTP promotes the calcium level in colostrum possibly by increasing intracellular calcium of mammary epithelial cells induced by the miR-99a-3p/ATP2B1 axis.

Genome-wide microRNA screening reveals miR-582-5p as a mesenchymal stem cell-specific microRNA in subchondral bone of the human knee joint

Emerging evidence suggests that microRNAs (miRNAs) may be pathologically involved in osteoarthritis (OA). Subchondral bone (SCB) sclerosis is accounted for the knee osteoarthritis (KOA) development and progression. In this study, we aimed to screen the miRNA biomarkers of KOA and investigated whether these miRNAs regulate the differentiation potential of mesenchymal stem cells (MSCs) and thus contributing to SCB. We identified 48 miRNAs in the blood samples in KOA patients (n = 5) through microarray expression profiling detection. After validation with larger sample number, we confirmed hsa-miR-582-5p and hsa-miR-424-5p were associated with the pathology of SCB sclerosis. Target genes prediction and pathway analysis were implemented with online databases, indicating these two candidate miRNAs were closely related to the pathways of pluripotency of stem cells and pathology of OA. Surprisingly, mmu-miR-582-5p (homology of hsa-miR-582-5p) was downregulated in osteogenic differentiation and upregulated in adipogenic differentiation of mesenchymal progenitor C3H10T1/2 cells, whereas mmu-mir-322-5p (homology of hsa-miR-424-5p) showed no change through the in vitro study. Supplementing mmu-miR-582-5p mimics blocked osteogenic and induced adipogenic differentiation of C3H10T1/2 cells, whereas silencing of the endogenous mmu-miR-582-5p enhanced osteogenic and repressed adipogenic differentiation. Further mechanism studies showed that mmu-miR-582-5p was directly targeted to Runx2. Mutation of putative mmu-miR-582-5p binding sites in Runx2 3' untranslated region (3'UTR) could abolish the response of the 3'UTR-luciferase construct to mmu-miR-582-5p supplementation. Generally speaking, our data suggest that miR-582-5p is an important biomarker of KOA and is able to regulate osteogenic and adipogenic differentiation of MSCs via targeting Runx2. The study also suggests that miR-582-5p may play a crucial role in SCB sclerosis of human KOA.