miRNA-376c-3p Mediates TWIST-1 Inhibition of Bone Marrow-Derived Stromal Cell Osteogenesis and Can Reduce Aberrant Bone Formation of TWIST-1 Haploinsufficient Calvarial Cells

Differentiation of osteoblasts: the links between essential transcription factors

Osteoblasts, cells derived from mesenchymal stem cells (MSCs) in the bone marrow, are cells responsible for bone formation and remodeling. The differentiation of osteoblasts from MSCs is triggered by the expression of specific genes, which are subsequently controlled by pro-osteogenic pathways. Mature osteoblasts then differentiate into osteocytes and are embedded in the bone matrix. Dysregulation of osteoblast function can cause inadequate bone formation, which leads to the development of bone disease. Various key molecules are involved in the regulation of osteoblastogenesis, which are transcription factors. Previous studies have heavily examined the role of factors that control gene expression during osteoblastogenesis, both in vitro and in vivo. However, the systematic relationship of these transcription factors remains unknown. The involvement of ncRNAs in this mechanism, particularly miRNAs, lncRNAs, and circRNAs, has been shown to influence transcriptional factor activity in the regulation of osteoblast differentiation. Here, we discuss nine essential transcription factors involved in osteoblast differentiation, including Runx2, Osx, Dlx5, β-catenin, ATF4, Ihh, Satb2, and Shn3. In addition, we summarize the role of ncRNAs and their relationship to these essential transcription factors in order to improve our understanding of the transcriptional regulation of osteoblast differentiation. Adequate exploration and understanding of the molecular mechanisms of osteoblastogenesis can be a critical strategy in the development of therapies for bone-related diseases.Communicated by Ramaswamy H. Sarma.

Unveiling Mesenchymal Stem Cells' Regenerative Potential in Clinical Applications: Insights in miRNA and lncRNA Implications

It is now widely recognized that mesenchymal stem cells (MSCs) possess the capacity to differentiate into a wide array of cell types. Numerous studies have identified the role of lncRNA in the regulation of MSC differentiation. It is important to elucidate the role and interplay of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in the regulation of signalling pathways that govern MSC function. Furthermore, miRNAs and lncRNAs are important clinical for innovative strategies aimed at addressing a wide spectrum of existing and emerging disease. Hence it is important to consider their impact on MSC function and differentiation. Examining the data available in public databases, we have collected the literature containing the latest discoveries pertaining to human stem cells and their potential in both fundamental research and clinical applications. Furthermore, we have compiled completed clinical studies that revolve around the application of MSCs, shedding light on the opportunities presented by harnessing the regulatory potential of miRNAs and lncRNAs. This exploration of the therapeutic possibilities offered by miRNAs and lncRNAs within MSCs unveils exciting prospects for the development of precision therapies and personalized treatment approaches. Ultimately, these advancements promise to augment the efficacy of regenerative strategies and produce positive outcomes for patients. As research in this field continues to evolve, it is imperative to explore and exploit the vast potential of miRNAs and lncRNAs as therapeutic agents. The findings provide a solid basis for ongoing investigations, fuelling the quest to fully unlock the regenerative potential of MSCs.

Impact of Environmental and Epigenetic Changes on Mesenchymal Stem Cells during Aging

Many crucial epigenetic changes occur during early skeletal development and throughout life due to aging, disease and are heavily influenced by an individual’s lifestyle. Epigenetics is the study of heritable changes in gene expression as the result of changes in the environment without any mutation in the underlying DNA sequence. The epigenetic profiles of cells are dynamic and mediated by different mechanisms, including histone modifications, non-coding RNA-associated gene silencing and DNA methylation. Given the underlining role of dysfunctional mesenchymal tissues in common age-related skeletal diseases such as osteoporosis and osteoarthritis, investigations into skeletal stem cells or mesenchymal stem cells (MSC) and their functional deregulation during aging has been of great interest and how this is mediated by an evolving epigenetic landscape. The present review describes the recent findings in epigenetic changes of MSCs that effect growth and cell fate determination in the context of aging, diet, exercise and bone-related diseases.

The Emerging Role of Non-Coding RNAs in Osteogenic Differentiation of Human Bone Marrow Mesenchymal Stem Cells

Autologous bone marrow-derived mesenchymal stem cells (BMSCs) are more easily available and frequently used for bone regeneration in clinics. Osteogenic differentiation of BMSCs involves complex regulatory networks affecting bone formation phenomena. Non-coding RNAs (ncRNAs) refer to RNAs that do not encode proteins, mainly including microRNAs, long non-coding RNAs, circular RNAs, piwi-interacting RNAs, transfer RNA-derived small RNAs, etc. Recent in vitro and in vivo studies had revealed the regulatory role of ncRNAs in osteogenic differentiation of BMSCs. NcRNAs had both stimulatory and inhibitory effects on osteogenic differentiation of BMSCs. During the physiological condition, osteo-stimulatory ncRNAs are upregulated and osteo-inhibitory ncRNAs are downregulated. The opposite effects might occur during bone degenerative disease conditions. Intracellular ncRNAs and ncRNAs from neighboring cells delivered via exosomes participate in the regulatory process of osteogenic differentiation of BMSCs. In this review, we summarize the recent advances in the regulatory role of ncRNAs on osteogenic differentiation of BMSCs during physiological and pathological conditions. We also discuss the prospects of the application of modulation of ncRNAs function in BMSCs to promote bone tissue regeneration in clinics.

Bioinformatics Analysis Identified miR-584-5p and Key miRNA-mRNA Networks Involved in the Osteogenic Differentiation of Human Periodontal Ligament Stem Cells

Human periodontal ligament cells (PDLCs) play an important role in periodontal tissue stabilization and function. In the process of osteogenic differentiation of PDLSCs, the regulation of molecular signal pathways are complicated. In this study, the sequencing results of three datasets on GEO were used to comprehensively analyze the miRNA-mRNA network during the osteogenic differentiation of PDLSCs. Using the GSE99958 and GSE159507, a total of 114 common differentially expressed genes (DEGs) were identified, including 62 up-regulated genes and 52 down-regulated genes. GO enrichment analysis was performed. The up-regulated 10 hub genes and down-regulated 10 hub genes were screened out by protein-protein interaction network (PPI) analysis and STRING in Cytoscape. Similarly, differentially expressed miRNAs (DEMs) were selected by limma package from GSE159508. Then, using the miRwalk website, we further selected 11 miRNAs from 16 DEMs that may have a negative regulatory relationship with hub genes. In vitro RT-PCR verification revealed that nine DEMs and 18 hub genes showed the same trend as the RNA-seq results during the osteogenic differentiation of PDLSCs. Finally, using miR-584-5p inhibitor and mimics, it was found that miR-584-5p negatively regulates the osteogenic differentiation of PDLSCs in vitro. In summary, the present results found several potential osteogenic-related genes and identified candidate miRNA-mRNA networks for the further study of osteogenic differentiation of PDLSCs.

miR-129-5p in exosomes inhibits diabetes-associated osteogenesis in the jaw via targeting FZD4

Diabetes mellitus (DM) influence induces poor osseointegration. The osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is a critical factor in successful dental implants. Certain microRNAs play important roles during bone development, and others are deregulated in diabetes. This study investigated the roles of miR-129-5p in the osteoblast differentiation regulation. Exosomes containing miR-129-5p inhibited the osteoblast differentiation and was found in the blood of DM rats. The BMSCs isolated from the jaw of rats were used to detect the miR-129-5p expression. Frizzled (FZD) proteins function as receptors for WNT ligands. The FZD4 was the target of miR-129-5p in dual luciferase assay and Western blot. The miR-129-5p inhibited osteoblast differentiation and decreased the osteoblast markers. The exosomes isolated from the blood of DM rats showed more miR-129-5p level. Results suggested that the exosomes containing miR-129-5p maybe regulators of BMSCs in jaw. The collected exosomes containing miR-129-5p showed the inhibition effect in osteoblast differentiation and decreased the expression osteoblastic markers by targeting FZD4/β-catenin signaling pathway. Therefore, the exosomes containing miR-129-5p in DM rats inhibits osteoblast differentiation by targeting FZD4/β-catenin pathway.

The role of microRNAs in the osteogenic and chondrogenic differentiation of mesenchymal stem cells and bone pathologies

Mesenchymal stem cells (MSCs) have been identified in many adult tissues. MSCs can regenerate through cell division or differentiate into adipocytes, osteoblasts and chondrocytes. As a result, MSCs have become an important source of cells in tissue engineering and regenerative medicine for bone tissue and cartilage. Several epigenetic factors are believed to play a role in MSCs differentiation. Among these, microRNA (miRNA) regulation is involved in the fine modulation of gene expression during osteogenic/chondrogenic differentiation. It has been reported that miRNAs are involved in bone homeostasis by modulating osteoblast gene expression. In addition, countless evidence has demonstrated that miRNAs dysregulation is involved in the development of osteoporosis and bone fractures. The deregulation of miRNAs expression has also been associated with several malignancies including bone cancer. In this context, bone-associated circulating miRNAs may be useful biomarkers for determining the predisposition, onset and development of osteoporosis, as well as in clinical applications to improve the diagnosis, follow-up and treatment of cancer and metastases. Overall, this review will provide an overview of how miRNAs activities participate in osteogenic/chondrogenic differentiation, while addressing the role of miRNA regulatory effects on target genes. Finally, the role of miRNAs in pathologies and therapies will be presented.

Comparative profile of exosomal microRNAs in postmenopausal women with various bone mineral densities by small RNA sequencing

To explore the role of plasma miRNAs in exosomes in early postmenopausal women. Small RNA sequencing was implemented to clarify the expression of miRNA in plasma exosomes obtained from 15 postmenopausal women, divided into groups of osteoporosis, osteopenia, and normal bone mass based on bone mineral density. Differentially expressed miRNAs (DEMs) were identified by comparing miRNA expression profiles. Five putative miRNAs, miR-224-3p, miR-25-5p, miR-302a-3p, miR-642a-3p, and miR-766-5p were confirmed by real-time PCR; miRNA target genes were obtained from 4 databases: miRWalk, miRDB, RNA22, and TargetScan. The miRNA-mRNA- Kyoto Encyclopedia of Genes and Genomes (KEGG) networks were analyzed, and the DEMs' potential role was investigated by gene ontology terms and KEGG pathway annotation. The results suggest that characterizing plasma exosomal miRNA profiles of early postmenopausal women by small RNA sequencing could identify novel exo-miRNAs involved in bone remodeling, and miR-642a-3p maybe contribute to the prediction and diagnosis of early postmenopausal osteoporosis.

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.

Inhibition of CRY2 by STAT3/miRNA-7-5p Promotes Osteoblast Differentiation through Upregulation of CLOCK/BMAL1/P300 Expression

Accumulating evidence indicates that cryptochrome circadian regulatory (CRY) proteins have emerged as crucial regulators of osteogenic differentiation. However, the associated mechanisms are quite elusive. In this study, we show that knockdown of CRY2 downregulated the expression of runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN) to facilitate osteoblast differentiation. Further study identified that CRY2 was directly targeted by microRNA (miR)-7-5p, which was highly induced during osteoblast differentiation. The expression of Runx2, ALP, collagen type I alpha 1 (Col1a1), and OCN was upregulated by overexpression of miR-7-5p and induction of osteoblast differentiation. Moreover, signal transducer and activator of transcription 3 (STAT3) transcriptionally activated miR-7-5p to significantly enhance the expression of above osteogenic marker genes and mineral formation. However, overexpression of CRY2 abolished the osteogenic differentiation induced by miR-7-5p overexpression. Silencing of CRY2 unraveled the binding of CRY2 with the circadian locomotor output cycles kaput (CLOCK)/brain and muscle ARNT-like 1 (BMAL1) complex to release CLOCK/BMAL1, which facilitated the binding of CLOCK/BMAL1 to the promoter region of the P300 E-box to stimulate the transcription of P300. P300 subsequently promoted the acetylation of histone 3 and the formation of a transcriptional complex with Runx2 to enhance osteogenesis. Taken together, our study revealed that CRY2 is repressed by STAT3/miR-7-5p to promote osteogenic differentiation through CLOCK/BMAL1/P300 signaling. The involved molecules may be potentially targeted for treatment of osteoporosis.

miR-26b modulates OA induced BMSC osteogenesis through regulating GSK3β/β-catenin pathway

BACKGROUNDS

Osteoactivin (OA) is a key regulator promoting bone marrow stromal cells osteogenesis progress, while Dexamethasone (Dex) could inhibit OA induced osteogenesis and lead to osteoporosis. miR-26b increased during BMSC osteogenesis but whether it participates in this progress is enigma. Osteogenesis is under regulation of canonical Wnt signaling pathway which could serve as potential target for miR-26b. It bears therapeutic potential if miR-26b could regulate osteogenesis and antagonize Dex induced Osteoporosis (OP).

METHODS

BMSC were isolated from bone marrow of rats and induced for osteogenesis by OA administration. We detected miR-26b mRNA level together with osteogenesis related genes or Wnt signal pathway related genes by qRT-PCR. BMSC cells with miR-26b inhibitor or mimics revealed the effect of miR-26b on osteogenesis. The osteogenesis efficiency was detected by Alizarin Red staining and ALP activity. Protein level of canonical Wnt signal pathway and other proteins were detected by Western blot. The interaction between miR-26b and GSK3β was detected by dual luciferase reporter assay.

RESULTS

We found that miR-26b was increased during OA induced BMSC osteogenesis. Inhibiting miR-26b could lead to osteogenesis inhibition while miR-26b mimics could promote this progress. The key regulator of Wnt signal pathway GSK3β is down-regulated when miR-26b was overexpressed, resulting in β-catenin activation. Since Dex could promote GSK3β expression and inhibit Wnt signal, miR-26b could also alleviate Dex induced osteogenesis inhibition.

CONCLUSION

Our findings indicate that miR-26b promoted BMSC osteogenesis by directly targeting GSK3β and activating canonical Wnt signal pathway, suggesting miR-26b might be serve as potential therapeutic candidate of osteoporosis.