Human multipotent stromal cells from bone marrow and microRNA: regulation of differentiation and leukemia inhibitory factor expression. Proc Natl Acad Sci U S A. 2008;105:18372-18377. [PMID: 19011087 DOI: 10.1073/pnas.0809807105]

The miRNA Contribution in Adipocyte Maturation

Mesenchymal stem cells, due to their multipotent ability, are considered one of the best candidates to be used in regenerative medicine. To date, the most used source is represented by the bone marrow, despite the limited number of cells and the painful/invasive procedure for collection. Therefore, the scientific community has investigated many alternative sources for the collection of mesenchymal stem cells, with the adipose tissue representing the best option, given the abundance of mesenchymal stem cells and the easy access. Although adipose mesenchymal stem cells have recently been investigated for their multipotency, the molecular mechanisms underlying their adipogenic potential are still unclear. In this scenario, this communication is aimed at defining the role of miRNAs in adipogenic potential of adipose-derived mesenchymal stem cells via real-time PCR. Even if preliminary, our data show that cell culture conditions affect the expression of specific miRNA involved in the adipogenic potential of mesenchymal stem cells. The in vitro/in vivo validation of these results could pave the way for novel therapeutic strategies in the field of regenerative medicine. In conclusion, our research highlights how specific cell culture conditions can modulate the adipogenic potential of adipose mesenchymal stem cells through the regulation of specific miRNAs.

Non-coding RNAs in Recurrent implantation failure

Recurrent implantation failure (RIF), defined as the inability to achieve conception following multiple consecutive in-vitro fertilization (IVF) attempts, represents a complex and multifaceted challenge in reproductive medicine. The emerging role of non-coding RNAs in RIF etiopathogenesis has only gained prominence over the last decade, illustrating a new dimension to our understanding of the intricate network underlying RIF. Successful embryo implantation demands a harmonious synchronization between an adequately decidualized endometrium, a competent blastocyst, and effective maternal-embryonic interactions. Emerging evidence has clarified the involvement of a sophisticated network of non-coding RNAs, including microRNAs, circular RNAs, and long non-coding RNAs, in orchestrating these pivotal processes. Disconcerted expression of these molecules can disrupt the delicate equilibrium required for implantation, amplifying the risk of RIF. This comprehensive review presents an in-depth investigation of the complex role played by non-coding RNAs in the pathogenesis of RIF. Furthermore, it underscores the vast potential of non-coding RNAs as diagnostic biomarkers and therapeutic targets, with the ultimate goal of enhancing implantation success rates in IVF cycles. As ongoing research continues to unravel the intercalated web of molecular interactions, exploiting the power of non-coding RNAs may offer promising avenues for mitigating the challenges posed by RIF and improving the outcomes of assisted reproduction.

Let-7a promotes periodontal bone regeneration of bone marrow mesenchymal stem cell aggregates via the Fas/FasL-autophagy pathway

Periodontal bone regeneration using bone marrow mesenchymal stem cell (BMMSC) transplantation is a promising method; however, the method for osteogenic differentiation of BMMSCs needs to be improved. In this research, we sought to identify the roles of let-7a in the osteogenesis of BMMSCs and to provide a potential method for periodontal bone regeneration. Our previous study revealed that Fas/FasL is a target of let-7a. In this study, we demonstrated that let-7a overexpression significantly enhanced BMMSC-CAs osteogenesis both in vitro and in vivo. Mechanistically, upregulation of Fas/FasL using the rfas/rfaslg plasmid obstructed the osteogenesis of BMMSCs by inhibiting autophagy. Furthermore, we confirmed that overexpression of let-7a activated autophagy and alleviated the inhibited osteogenesis by the autophagy inhibitor 3-MA and the rfas/rfaslg plasmid of BMMSCs. In general, our findings showed that let-7a promoted the osteogenesis of BMMSCs through the Fas/FasL-autophagy pathway, suggesting that the application of let-7a in BMMSC-CAs based periodontal bone regeneration could be a promising strategy.

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.

Advances in the regulation of adipogenesis and lipid metabolism by exosomal ncRNAs and their role in related metabolic diseases

Exosomes are membrane-bound extracellular vesicles released following the fusion of multivesicular bodies (MVBs) with the cell membrane. Exosomes transport diverse molecules, including proteins, lipids, DNA and RNA, and regulate distant intercellular communication. Noncoding RNA (ncRNAs) carried by exosomes regulate cell-cell communication in tissues, including adipose tissue. This review summarizes the action mechanisms of ncRNAs carried by exosomes on adipocyte differentiation and modulation of adipogenesis by exosomal ncRNAs. This study aims to provide valuable insights for developing novel therapeutics.

Mesoporous Core-Cone Silica Nanoparticles Can Deliver miRNA-26a to Macrophages to Exert Immunomodulatory Effects on Osteogenesis In Vitro

Nanoparticles can play valuable roles in delivering nucleic acids, including microRNAs (miRNA), which are small, non-coding RNA segments. In this way, nanoparticles may exert post-transcriptional regulatory influences on various inflammatory conditions and bone disorders. This study used biocompatible, core-cone-structured, mesoporous silica nanoparticles (MSN-CC) to deliver miRNA-26a to macrophages in order to influence osteogenesis in vitro. The loaded nanoparticles (MSN-CC-miRNA-26) showed low-level toxicity towards macrophages (RAW 264.7 cells) and were internalized efficiently, causing the reduced expression of pro-inflammatory cytokines, as seen via real-time PCR and cytokine immunoassays. The conditioned macrophages created a favorable osteoimmune environment for MC3T3-E1 preosteoblasts, driving osteogenic differentiation with enhanced osteogenic marker expression, alkaline phosphatase (ALP) production, extracellular matrix formation, and calcium deposition. An indirect co-culture system revealed that direct osteogenic induction and immunomodulation by MSN-CC-miRNA-26a synergistically increased bone production due to the crosstalk between MSN-CC-miRNA-26a-conditioned macrophages and MSN-CC-miRNA-26a-treated preosteoblasts. These findings demonstrate the value of nanoparticle delivery of miR-NA-26a using MSN-CC for suppressing the production of pro-inflammatory cytokines with macrophages and for driving osteogenic differentiation in preosteoblasts via osteoimmune modulation.

The Role of Epicardial Adipose Tissue-Derived MicroRNAs in the Regulation of Cardiovascular Disease: A Narrative Review

Cardiovascular diseases have been leading cause of death worldwide for many decades, and obesity has been acknowledged as a risk factor for cardiovascular diseases. In the present review, human epicardial adipose tissue-derived miRNAs reported to be differentially expressed under pathologic conditions are discussed and summarized. The results of the literature review indicate that some of the epicardial adipose tissue-derived miRNAs are believed to be cardioprotective, while some others show quite the opposite effects depending on the underlying pathologic conditions. Furthermore, they suggest that that the epicardial adipose tissue-derived miRNAs have great potential as both a diagnostic and therapeutic modality. Nevertheless, mainly due to highly limited availability of human samples, it is very difficult to make any generalized claims on a given miRNA in terms of its overall impact on the cardiovascular system. Therefore, further functional investigation of a given miRNA including, but not limited to, the study of its dose effect, off-target effects, and potential toxicity is required. We hope that this review can provide novel insights to transform our current knowledge on epicardial adipose tissue-derived miRNAs into clinically viable therapeutic strategies for preventing and treating cardiovascular diseases.

MicroRNAs: a crossroad that connects obesity to immunity and aging

Obesity is characterized by an elevated amount of fat and energy storage in the adipose tissue (AT) and is believed to be the root cause of many metabolic diseases (MDs). Obesity is associated with low-grade chronic inflammation in AT. Like obesity, chronic inflammation and MDs are prevalent in the elderly. The resident immune microenvironment is not only responsible for maintaining AT homeostasis but also plays a crucial role in stemming obesity and related MDs. Mounting evidence suggests that obesity promotes activation in resident T cells and macrophages. Additionally, inflammatory subsets of T cells and macrophages accumulated into the AT in combination with other immune cells maintain low-grade chronic inflammation. microRNAs (miRs) are small non-coding RNAs and a crucial contributing factor in maintaining immune response and obesity in AT. AT resident T cells, macrophages and adipocytes secrete various miRs and communicate with other cells to create a potential effect in metabolic organ crosstalk. AT resident macrophages and T cells-associated miRs have a prominent role in regulating obesity by targeting several signaling pathways. Further, miRs also emerged as important regulators of cellular senescence and aging. To this end, a clear link between miRs and longevity has been demonstrated that implicates their role in regulating lifespan and the aging process. Hence, AT and circulating miRs can be used as diagnostic and therapeutic tools for obesity and related disorders. In this review, we discuss how miRs function as biomarkers and impact obesity, chronic inflammation, and aging.

Promotion effect of apical tooth germ cell-conditioned medium on osteoblastic differentiation of periodontal ligament stem cells through regulating miR-146a-5p

BACKGROUND

MicroRNAs (miRNAs) play an important role in gene regulation that controls stem cells differentiation. Periodontal ligament stem cells (PDLSCs) could differentiate into osteo-/cementoblast-like cells that secretes cementum-like matrix both in vitro and in vivo. Whether miRNAs play key roles in osteoblastic differentiation of PDLSCs triggered by a special microenviroment remains elusive. In this study, we aimed to investigate potential miRNA expression changes in osteoblastic differentiation of PDLSCs by the induction of apical tooth germ cell-conditioned medium (APTG-CM).

METHODS AND RESULTS

First, we analyzed the ability of APTG-CM to osteogenically differentiate PDLSCs. The results exhibited an enhanced mineralization ability, higher ALP activity and increased expression of osteogenic genes in APTG-CM-induced PDLSCs. Second, we used miRNA sequencing to analyze the miRNA expression profile of PDLSCs derived from three donors under 21-day induction or non-induction of APTG-CM. MiR-146a-5p was found to be up-regulated miRNA in induced PDLSCs and validated by RT-qPCR. Third, we used lentivirus-up/down system to verify the role of miR-146a-5p in the regulation of osteoblastic differentiation of PDLSCs.

CONCLUSIONS

In conclusion, our results demonstrated that miR-146a-5p was involved in the promotion effect of APTG-CM on osteoblastic differentiation of PDLSCs, and suggested that miR-146a-5p might be a novel way in deciding the direction of PDLSCs differentiation.

LncRNA-412.25 activates the LIF/STAT3 signaling pathway in ovarian granulosa cells of Hu sheep by sponging miR-346

Although long non-coding RNAs (lncRNAs) are reported to regulate follicular development and reproductive disease pathogenesis, the underlying mechanisms have not been elucidated. In this study, lncRNA expression profiling of different-sized healthy follicles from Hu sheep with different prolificacy revealed 50 613 lncRNAs. Numerous lncRNAs were differentially expressed among different comparison groups. This study characterized one novel transcript, lncRNA-412.25 (from healthy follicles with a diameter of >5 mm), which was predominantly expressed in the high prolificacy group and localized to the cytoplasm of granulosa cells (GCs). LncRNA-412.25 knockdown promoted and inhibited Hu sheep GC apoptosis and proliferation, respectively. Interestingly, lncRNA-412.25 could directly bind to miR-346, which can target the gene of leukemia inhibitory factor (LIF). Knockdown of lncRNA-412.25 promoted GC apoptosis by downregulating LIF expression, where this effect was attenuated by miR-346. Moreover, the miR-346 inhibitor mitigated the lncRNA-412.25 knockdown-induced downregulation of phosphorylated protein of signal transducer and activator of transcription 3 (STAT3), which was validated using immunofluorescence analysis. Our results demonstrated that lncRNA-412.25 regulates GC proliferation and apoptosis in Hu sheep by binding to miR-346 and then activating the LIF/STAT3 pathway. These findings provide novel insights into the mechanisms underlying prolificacy in sheep.

Identification of potential miRNA-mRNA regulatory network and the key miRNAs in intramuscular and subcutaneous adipose

Intramuscular fat (IMF) is an important indicator for evaluating meat quality. Breeds with high IMF content are often accompanied by high subcutaneous fat (SCF), severely affecting the meat rate of pigs. Studying the mechanisms of miRNAs related to lipogenesis and lipid metabolism has important implications for pig breeding. We constructed two small RNA libraries from intramuscular and subcutaneous fat to evaluate the patterns of lipogenesis in Laiwu pig, a Chinese breed. A total of 286 differentially expressed miRNAs (DEmiRNAs), including 193 known miRNA and 93 novel miRNAs, were identified from two types of adipose. GO and KEGG enrichment analysis for DEmiRNAs showed that their target genes involved in many adipogenesis and lipid metabolism biological processes and signaling pathways, such as Wnt signaling pathway,MAPK signaling pathway, Hippo signaling pathway, PI3K-Akt signaling pathway, Melanogenesis, Signaling pathways regulating pluripotency of stem cells and so on. Then, we constructed a miRNA-mRNA interaction network to find out which miRNAs were the key miRNAs of regulation in Wnt signaling pathway. In this pathway, miR-331-3p, miR-339-5p, miR-874 and novel346_mature target PPARD, WNT10B, RSPO3, WNT2B. This study provides a theoretical basis for further understanding the post-transcriptional regulation mechanism of meat quality formation and predicting and treating diseases caused by ectopic fat.

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.

Inflammation-Stimulated MSC-Derived Small Extracellular Vesicle miR-27b-3p Regulates Macrophages by Targeting CSF-1 to Promote Temporomandibular Joint Condylar Regeneration

Small extracellular vesicles (sEVs) secreted by mesenchymal stem cells (MSCs) have been extensively studied in recent years. sEV contents change with the secreting cell state. When MSCs are exposed to an inflammatory environment, they release more functional growth factors, exosomes, and chemokines. Herein, MSCs are stimulated to alter sEV cargos and functions to regulate the inflammatory microenvironment and promote tissue regeneration. Sequencing of sEV miRNAs shows that certain RNAs conducive to cell function are upregulated. In this study, in vitro cell function experiments show that both inflammation-stimulated adipose-derived MSC (ADSC)-derived sEV (IAE) and normal ADSC-derived sEV (AE) promote cell proliferation; IAE also significantly improves cell migration. Regarding macrophage polarization regulation, IAE significantly promotes M2 macrophage differentiation. RNA-sequencing analysis indicates that high miR-27b-3p expression levels in IAE may regulate macrophages by targeting macrophage colony-stimulating factor-1 (CSF-1). In vivo, a rabbit temporomandibular joint (TMJ) condylar osteochondral defect model shows that both AE and IAE promote TMJ regeneration, with IAE having the most significant therapeutic effect. Therefore, the authors confirm that exposing MSCs to an inflammatory environment can feasibly enhance sEV functions and that modified sEVs achieve better therapeutic effects.

Tumor suppressor LHX6 upregulation contributes to the inhibitory effect of miR-346 knockdown on colorectal cancer cell growth

Colorectal cancer (CRC) is one of the prevalent types of human malignancies and ranks as the second leading cause of cancer-associated death worldwide. Dysregulated miRNAs have been promulgated as oncogenes or tumor-suppressive genes participating in the initiation and progression of CRC. A recent study reported that miR-346 was highly expressed in CRC patients. However, the biological role and underlying mechanism of miR-346 in CRC remain elusive. qRT-PCR and western blot assays were employed to detect miR-346 and LIM homeobox domain 6 (LHX6) expression in CRC cells. Cell proliferation was evaluated by CCK-8 and BrdU assays. Apoptosis was evaluated by TUNEL assay. The interaction between miR-346 and LHX6 was assessed by luciferase reporter assay. Results showed that miR-346 expression was increased and LHX6 expression was reduced in CRC cells. miR-346 knockdown and LHX6 overexpression inhibited proliferation and promoted apoptosis of CRC cells. Additionally, we found that miR-346 negatively regulated LHX6 expression in CRC cells by directly targeting LHX6. LHX6 knockdown partially attenuated anti-miR-346-induced proliferation reduction and apoptosis promotion in CRC cells. Furthermore, miR-346 knockdown inhibited the protein kinase B (Akt)/mechanistic target of rapamycin (mTOR) pathway in CRC cells by targeting LHX6. The present study indicated that miR-346 knockdown repressed cell growth in CRC cells by upregulating LHX6, and this was associated with inactivation of the Akt/mTOR pathway.

microRNA-136-5p from bone marrow mesenchymal stem cell-derived exosomes facilitates fracture healing by targeting LRP4 to activate the Wnt/β-catenin pathway

Aims

Exosomes derived from bone marrow mesenchymal stem cells (BMSCs) have been reported to be a promising cellular therapeutic approach for various human diseases. The current study aimed to investigate the mechanism of BMSC-derived exosomes carrying microRNA (miR)-136-5p in fracture healing.

Methods

A mouse fracture model was initially established by surgical means. Exosomes were isolated from BMSCs from mice. The endocytosis of the mouse osteoblast MC3T3-E1 cell line was analyzed. CCK-8 and disodium phenyl phosphate microplate methods were employed to detect cell proliferation and alkaline phosphatase (ALP) activity, respectively. The binding of miR-136-5p to low-density lipoprotein receptor related protein 4 (LRP4) was analyzed by dual luciferase reporter gene assay. HE staining, tartrate-resistant acid phosphatase (TRAP) staining, and immunohistochemistry were performed to evaluate the healing of the bone tissue ends, the positive number of osteoclasts, and the positive expression of β-catenin protein, respectively.

Results

miR-136-5p promoted fracture healing and osteoblast proliferation and differentiation. BMSC-derived exosomes exhibited an enriched miR-136-5p level, and were internalized by MC3T3-E1 cells. LRP4 was identified as a downstream target gene of miR-136-5p. Moreover, miR-136-5p or exosomes isolated from BMSCs (BMSC-Exos) containing miR-136-5p activated the Wnt/β-catenin pathway through the inhibition of LRP4 expression. Furthermore, BMSC-derived exosomes carrying miR-136-5p promoted osteoblast proliferation and differentiation, thereby promoting fracture healing.

Conclusion

BMSC-derived exosomes carrying miR-136-5p inhibited LRP4 and activated the Wnt/β-catenin pathway, thus facilitating fracture healing.

Cite this article: Bone Joint Res 2021;10(12):744–758.

microRNAs in Human Adipose Tissue Physiology and Dysfunction

In recent years, there has been a large amount of evidence on the role of microRNA (miRNA) in regulating adipose tissue physiology. Indeed, miRNAs control critical steps in adipocyte differentiation, proliferation and browning, as well as lipolysis, lipogenesis and adipokine secretion. Overnutrition leads to a significant change in the adipocyte miRNOME, resulting in adipose tissue dysfunction. Moreover, via secreted mediators, dysfunctional adipocytes may impair the function of other organs and tissues. However, given their potential to control cell and whole-body energy expenditure, miRNAs also represent critical therapeutic targets for treating obesity and related metabolic complications. This review attempts to integrate present concepts on the role miRNAs play in adipose tissue physiology and obesity-related dysfunction and data from pre-clinical and clinical studies on the diagnostic or therapeutic potential of miRNA in obesity and its related complications.

Argonaute (AGO) proteins play an essential role in mediating BMP9-induced osteogenic signaling in mesenchymal stem cells (MSCs)

As multipotent progenitor cells, mesenchymal stem cells (MSCs) can renew themselves and give rise to multiple lineages including osteoblastic, chondrogenic and adipogenic lineages. It's previously shown that BMP9 is the most potent BMP and induces osteogenic and adipogenic differentiation of MSCs. However, the molecular mechanism through which BMP9 regulates MSC differentiation remains poorly understood. Emerging evidence indicates that noncoding RNAs, especially microRNAs, may play important roles in regulating MSC differentiation and bone formation. As highly conserved RNA binding proteins, Argonaute (AGO) proteins are essential components of the multi-protein RNA-induced silencing complexes (RISCs), which are critical for small RNA biogenesis. Here, we investigate possible roles of AGO proteins in BMP9-induced lineage-specific differentiation of MSCs. We first found that BMP9 up-regulated the expression of Ago1, Ago2 and Ago3 in MSCs. By engineering multiplex siRNA vectors that express multiple siRNAs targeting individual Ago genes or all four Ago genes, we found that silencing individual Ago expression led to a decrease in BMP9-induced early osteogenic marker alkaline phosphatase (ALP) activity in MSCs. Furthermore, we demonstrated that simultaneously silencing all four Ago genes significantly diminished BMP9-induced osteogenic and adipogenic differentiation of MSCs and matrix mineralization, and ectopic bone formation. Collectively, our findings strongly indicate that AGO proteins and associated small RNA biogenesis pathway play an essential role in mediating BMP9-induced osteogenic differentiation of MSCs.

The Role of miR-34c-5p in Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells

Background and Objectives

Osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) plays a critical role in the success of lumbar spinal fusion with autogenous bone graft. This study aims to explore the role and specific mechanism of miR-34c-5p in osteogenic differentiation of BMSCs.

Methods and Results

Rabbit model of lumbar fusion was established by surgery. The osteogenic differentiation dataset of mesenchymal stem cells was obtained from the Gene Expression Omnibus (GEO) database, and differentially expressed miRNAs were analyzed using R language (limma package). The expressions of miR-34c-5p, miR-199a-5p, miR-324-5p, miR-361-5p, RUNX2, OCN and Bcl-2 were determined by qRT-PCR and Western blot. ELISA, Alizarin red staining and CCK-8 were used to detect the ALP content, calcium deposition and proliferation of BMSCs. The targeted binding sites between miR-34c-5p and Bcl-2 were predicted by the Target database and verified using dual-luciferase reporter assay. MiR-34c-5p expression was higher in rabbit lumbar fusion model and differentiated BMSCs than normal rabbit or BMSCs. The content of ALP and the deposition of calcium increased with the osteogenic differentiation of BMSCs. Upregulation of miR-34c-5p reduced cell proliferation and promoted ALP content, calcium deposition, RUNX2 and OCN expression compared with the control group. The effects of miR-34c-5p inhibitor were the opposite. In addition, miR-34c-5p negatively correlated with Bcl-2. Upregulation of Bcl-2 reversed the effects of miR-34c-5p on ALP content, calcium deposition, and the expressions of RUNX2 and OCN.

Conclusions

miR-34c-5p could promote osteogenic differentiation and suppress proliferation of BMSCs by inhibiting Bcl-2.

The role of leukemia inhibitory factor in pathogenesis of pre-eclampsia: molecular and cell signaling approach

Endothelial dysfunction is considered as the main hallmark of Preeclampsia (PE). Despite the unknown pathogenesis of PE, different possible causes have been suggested in various studies. In this review, we first studied the Leukemia inhibitory factor (LIF) role in the related pathways to the PE pathogenesis, such as inflammation, endothelial dysfunction and hypertension. LIF can increase the expression of ICAM-1 and VCAM-1 via the JAK/STAT3 pathway, thereby inducing inflammatory responses and endothelial dysfunction. It can also be involved in the vascular vasoconstriction and hypertension by reducing the nitric oxide (NO) synthesis. Identifying the link between LIF and pathways associated with PE pathogenesis could be effective to achieve an effective PE treatment in the future.

Tissue and circulating microRNAs as biomarkers of response to obesity treatment strategies

BACKGROUND

Obesity, characterized by an increased amount of adipose tissue, is a metabolic chronic alteration which has reached pandemic proportion. Lifestyle changes are the first line therapy for obesity and a large variety of dietary approaches have demonstrated efficacy in promoting weight loss and improving obesity-related metabolic alterations. Besides diet and physical activity, bariatric surgery might be an effective therapeutic strategy for morbid obese patients. Response to weight-loss interventions is characterised by high inter-individual variability, which might involve epigenetic factors. microRNAs have critical roles in metabolic processes and their dysregulated expression has been reported in obesity.

AIM

The aim of this review is to provide a comprehensive overview of current studies evaluating changes in microRNA expression in obese patients undergoing lifestyle interventions or bariatric surgery.

RESULTS

A considerable number of studies have reported a differential expression of circulating microRNAs before and after various dietary and bariatric surgery approaches, identifying several candidate biomarkers of response to weight loss. Significant changes in microRNA expression have been observed at a tissue level as well, with entirely different patterns between visceral and subcutaneous adipose tissue. Interestingly, relevant differences in microRNA expression have emerged between responders and non-responders to dietary or surgical interventions. A wide variety of dysregulated microRNA target pathways have also been identified, helping to understand the pathophysiological mechanisms underlying obesity and obesity-related metabolic diseases.

CONCLUSIONS

Although further research is needed to draw firm conclusions, there is increasing evidence about microRNAs as potential biomarkers for weight loss and response to intervention strategies in obesity.

MicroRNA treatment modulates osteogenic differentiation potential of mesenchymal stem cells derived from human chorion and placenta

Mesenchymal stem cells (MSCs) are important in regenerative medicine because of their potential for multi-differentiation. Bone marrow, chorion and placenta have all been suggested as potential sources for clinical application. However, the osteogenic differentiation potential of MSCs derived from chorion or placenta is not very efficient. Bone morphogenetic protein-2 (BMP-2) plays an important role in bone development. Its effect on osteogenic augmentation has been addressed in several studies. Recent studies have also shown a relationship between miRNAs and osteogenesis. We hypothesized that miRNAs targeted to Runt-related transcription factor 2 (Runx-2), a major transcription factor of osteogenesis, are responsible for regulating the differentiation of MSCs into osteoblasts. This study examines the effect of BMP-2 on the osteogenic differentiation of MSCs isolated from chorion and placenta in comparison to bone marrow-derived MSCs and investigates the role of miRNAs in the osteogenic differentiation of MSCs from these sources. MSCs were isolated from human bone marrow, chorion and placenta. The osteogenic differentiation potential after BMP-2 treatment was examined using ALP staining, ALP activity assay, and osteogenic gene expression. Candidate miRNAs were selected and their expression levels during osteoblastic differentiation were examined using real-time RT-PCR. The role of these miRNAs in osteogenesis was investigated by transfection with specific miRNA inhibitors. The level of osteogenic differentiation was monitored after anti-miRNA treatment. MSCs isolated from chorion and placenta exhibited self-renewal capacity and multi-lineage differentiation potential similar to MSCs isolated from bone marrow. BMP-2 treated MSCs showed higher ALP levels and osteogenic gene expression compared to untreated MSCs. All investigated miRNAs (miR-31, miR-106a and miR148) were consistently downregulated during the process of osteogenic differentiation. After treatment with miRNA inhibitors, ALP activity and osteogenic gene expression increased over the time of osteogenic differentiation. BMP-2 has a positive effect on osteogenic differentiation of chorion- and placenta-derived MSCs. The inhibition of specific miRNAs enhanced the osteogenic differentiation capacity of various MSCs in culture and this strategy might be used to promote bone regeneration. However, further in vivo experiments are required to assess the validity of this approach.

microRNA-199a counteracts glucocorticoid inhibition of bone marrow mesenchymal stem cell osteogenic differentiation through regulation of Klotho expression in vitro

Osteogenic differentiation (OD) of bone marrow mesenchymal stem cells (BMSCs) is critically important for mitigation of osteoporosis. Glucocorticoids (GCs) are extensively used for treating chronic inflammation, although long-term exposure to GCs is capable of triggering osteoporosis. microRNAs (miRNAs) have been reported to play a critical role in bone diseases. In the present study, we treated BMSCs with dexamethasone (DEX) during OD to stimulate GC-mediated osteoporosis. Microarray and quantitative polymerase chain reaction (Q-PCR) assays demonstrated that miR-199a was upregulated during OD of BMSCs, while DEX treatment caused a significant reduction in miR-199a. Alkaline phosphatase (ALP) activity, Alizarin red (AR) staining, and Q-PCR were applied to assess the role of miRNA-199a overexpression in DEX-triggered OD inhibition. miR-199a was able to rescue OD and ALP activity, which were inhibited by DEX. Additionally, we observed that ALP, BMP2, COL1A1, and Runx2 were increased after transfection of miRNA-199a mimics. Furthermore, we confirmed that miRNA-199a facilitates OD of BMSCs through direct inhibition of Klotho protein and messenger RNA expression affecting the downstream fibroblast growth factor receptor 1/extracellular-signal-regulated kinase and Janus kinase 1/signal transducer and activator of transcription 1 pathways. This study indicates that miR-199a plays a critical role in preventing GC-mediated osteoblast differentiation and may function as a promising miRNA biomarker for osteoporosis.

Leukemia Inhibitory Factor (LIF) Overexpression Increases the Angiogenic Potential of Bone Marrow Mesenchymal Stem/Stromal Cells

Mesenchymal stem/stromal cells (MSCs) have the ability to secrete bioactive molecules, exerting multiple biological effects, such as tissue regeneration, reduction of inflammation, and neovascularization. The therapeutic potential of MSCs can be increased by genetic modification to overexpress cytokines and growth factors. Here we produced mouse MSCs overexpressing human leukemia inhibitory factor (LIF) to assess their proangiogenic potential in vitro and in vivo. Mouse bone marrow-derived MSCs were transduced by using a second-generation lentiviral system to express human LIF. Leukemia inhibitory factor expression was confirmed by RT-qPCR and by ELISA, allowing the quantification of the transcript and secreted protein, respectively. Flow cytometry analysis and trilineage differentiation assay showed that the MSC_LIF cell line maintained the immunophenotype and a multipotency characteristic of MSCs. The immunosuppressive activity of MSC_LIF was confirmed using a lymphoproliferation assay. Moreover, gene expression analysis demonstrated upregulation of genes coding for strategic factors in the neovascularization process, such as angiogenin, IL-8, MCP-1, and VEGF, and for the perivascular cell markers αSMA, Col4a1, SM22, and NG2. To evaluate the pro-angiogenic potential of MSC_LIF, we first tested its effects on endothelial cells obtained from umbilical vein in a scratch wound healing assay. Conditioned medium (CM) from MSC_LIF promoted a significant increase in cell migration compared to CM from control MSC. Additionally, in vitro tube formation of endothelial cells was increased by the presence of MSC_LIF, as shown in microvessel sprouting in aortic ring cultures. Finally, an in vivo Matrigel plug assay was performed, showing that MSC_LIF were more potent in promoting in vivo angiogenesis and tissue vascularization than control MSCs. In conclusion, LIF overexpression is a promising strategy to increase the proangiogenic potential of MSCs and sets precedents for future investigations of their potential applications for the treatment of ischemic diseases and tissue repair.

Depot-Specific Analysis of Human Adipose Cells and Their Responses to Bisphenol S

Exposure to endocrine-disrupting chemicals (EDCs) is associated with adverse health outcomes including obesity and diabetes. Obesity, and more specifically visceral obesity, is correlated with metabolic disease. The adipose tissue is an endocrine organ and a potential target for many environmental pollutants including bisphenols. The subcutaneous (Sc) and the omental (Om, visceral) depots are composed of mature adipocytes and residing progenitors, which may be different between the depots and may be EDCs targets. Bisphenol A (BPA) is a suspected metabolic disruptor, and is being replaced with structurally similar compounds such as bisphenol S (BPS). Like BPA, BPS induces adipogenesis in murine and primary human Sc preadipocytes. However, the effect of BPS on Om preadipocytes is not known. In this study, we show that human primary progenitors from Om depots have a distinct transcriptomic signature as compared to progenitors derived from donor-matched Sc depots. Furthermore, we show that BPS increases adipogenesis both of Om and Sc preadipocytes and can mimic the action of glucocorticoids or peroxisome proliferator-activated receptor γ (PPARγ) agonists. We also show that BPS treatment, at 0.1 µM and 25 µM, modifies the adipokine profiles both of Om- and Sc-derived adipocytes in a depot-specific manner. Taken together our data show distinct gene expression profiles in the Om vs Sc progenitors and similar responses to the BPA analogue, BPS.

Citrus aurantium L. Dry Extracts Ameliorate Adipocyte Differentiation of 3T3-L1 Cells Exposed to TNFα by Down-Regulating miR-155 Expression

Citrus aurantium L. dry extracts (CAde) improve adipogenesis in vitro. These effects are dependent from an early modulation of CCAAT/enhancer-binding protein beta (C/Ebpβ) expression and cyclic Adenosine Monophosphate (cAMP) response element-binding protein (CREB) activation. C/Ebpβ and Creb are also targets of miR-155. This study investigated whether CAde regulates miR-155 expression in the early stages of adipogenesis and whether it ameliorates adipocyte differentiation of cells exposed to tumor necrosis factor-alpha (TNFα). Adipogenic stimuli (AS) were performed in 3T3-L1 pre-adipocytes treated with CAde, TNFα, or both. Gene and miRNA expression were determined by quantitative real-time PCR. Adipogenesis was evaluated by Oil-Red O staining. CAde treatment enhanced AS effects during the early adipogenesis phases by further down-regulating miR-155 expression and increasing both C/Ebpβ and Creb mRNA and protein levels. At variance, TNFα inhibited 3T3-L1 adipogenesis and abolished AS effects on miR-155, C/Ebpβ, and Creb expression. However, in cells exposed to TNFα, CAde improved adipocyte differentiation and restored the AS effects on miRNA and gene expression at early time points. In conclusion, this study identified miR-155 down-regulation as part of the mechanism through which CAde enhances adipogenesis of pre-adipocytes in vitro. Furthermore, it provides evidence of CAde efficacy against TNFα negative effects on adipogenesis.

Prognostic values of YTHDF1 regulated negatively by mir-3436 in Glioma

M6A methylation is likely to be closely associated with the occurrence and development of tumours. In this study, we demonstrated that the transcription levels of the m6A RNA methylation regulators are closely related to the prognosis of glioma. Univariate Cox analysis was performed on the expression levels of methylation regulators and selected three hub genes in glioma. Next, we systematically compared the expression of these m6A RNA methylation regulators in gliomas with different clinicopathological features. The overall survival (OS) curve of the hub genes was initially established based on TCGA database information. YTHDF1 was selected from the hub genes following survival and prognosis analysis. A nomogram was developed to predict the survival probability. We further performed cell function and in vivo xenograft tumour experiments to further verify its role in tumour progression. Next, based on the miRanda and miRDB databases, we predicted one microRNA, hsa-mir-346, that might regulate and bind to 3'UTR of YTHDF1, which was confirmed by our fluorescent enzyme reporter gene experiment. In summary, m6A RNA methylation regulators play a potential role in the progression of gliomas. YTHDF1 may have an essential function in glioma diagnosis, treatment and prognosis.

Expression profiling and analysis of some miRNAs in subcutaneous white adipose tissue during development of obesity

Background

MicroRNAs are emerging as new mediators in the regulation of adipocyte physiology and have been approved to play a role in obesity. Despite several studies have focused on microRNA expression profiles and functions in different metabolic tissues, little is known about their response to nutritional interventions in white adipose tissue during obesity stages, and whether they differ in this response to weight-reduction strategy is poorly understood. Our objectives were to study the dysregulation of some miRNAs in subcutaneous inguinal white adipose tissue during weight change, expansion/reduction; in response to both a high-fat diet and switching to a normal diet feeding, and to evaluate them as potential biomarkers and therapeutic targets for early obesity management

Method

A hundred 6-week-old male Wister rats were randomly divided into a normal diet group (N.D), a high-fat diet group (H.F.D), and a switched to a normal diet group (H.F.D/N.D). At the beginning and at intervals 2 weeks, serum lipid, hormone levels, total body fat mass, and inguinal subcutaneous white adipose tissue mass (WAT) measurements were recorded using dual-energy X-ray absorptiometry (DEXA). The expression levels of microRNAs were evaluated using real-time PCR.

Results

Significant alterations were observed in serum glucose, lipid profile, and adipokine hormones during the early stages of obesity development. Alteration in rno-mir 30a-5p, rno-mir 133a-5p, and rno-mir 107-5p expression levels were observed at more than one time point. While rno-let-7a-5p, rno-mir 193a-5p, and rno-mir125a-5p were downregulated and rno-mir130a-5p was upregulated at all time points within 2 to 4 weeks in response to H.F.D feeding for 10 weeks. The impact of switching to normal diet has a reversed effect on lipid profile, adipokine hormone levels, and some miRNAs. The bioinformatics results have identified a novel and important pathway related to inflammatory signalling.

Conclusion

Our research demonstrated significant alterations in some adipocyte-expressed miRNAs after a short time of high caloric diet consumption. This provides further evidence of the significant role of nutrition as an epigenetic factor in regulation of lipid and glucose metabolism genes by modulating of related key miRNAs. Therefore, we suggest that miRNAs could be used as biomarkers for adiposity during diet-induced obesity. Perhaps limitation in calories intake is a way to manipulate obesity and associated metabolic disorders. Further studies are needed to fully elucidate the role of microRNAs in the development of obesity

Physiologic Events of Embryo Implantation and Decidualization in Human and Non-Human Primates

Reproduction is a fundamental process for the preservation of the human species. This process requires a sequence of orchestrated events that are necessary for a successful pregnancy. Two of the most critical steps in the establishment of human pregnancy are implantation and decidualization, which are required for maternal interactions with the developing embryo. This review primarily highlights the physiological aspects of these two events and the adverse pregnancy outcomes from defective implantation and decidualization. The focus of this review is to provide a general concept of the mechanisms involved during the window of implantation, description of components involved in the process and possible pathologies that could disrupt the embryo implantation and decidualization and specifically as it applies to women and non-human primates.

miR-346 Inhibited Apoptosis Against Myocardial Ischemia-Reperfusion Injury via Targeting Bax in Rats

Purpose

Myocardial ischemia-reperfusion injury (MIRI) is a common pathophysiological process after occlusion of the blood vessels to restore blood supply. Apoptosis is one of the ways of myocardial cell death in this process. MicroRNAs (miRNAs), a class of short and noncoding RNAs, are involved in multiple biological processes by post-transcriptionally targeting their downstream effectors. To date, whether miRNAs exert biological effects in myocardial ischemia-reperfusion (I/R) injury remains to be further studied.

Methods

In this study, we induced MIRI model by ligating rat left anterior descending artery (LAD) for 30 mins and reperfusion for 2 hrs. The differential expression profile of miRNAs in rat models of MIRI was analyzed by miRNAs sequencing.

Results

We found that miRNAs sequencing analysis showed the expressions of 15 types of miRNAs, including miR-346, were downregulated and 29 types of miRNAs were elevated in the MIRI rat model. We observed the key regulator of apoptosis Bax was a predicted downstream target of miR-346 using online software TargetScan. And luciferase reporter assay was utilized to certify this prediction. Over-expression of miR-346 can attenuate myocardial injury and narrow infarct area by inhibiting myocardial cell apoptosis in rat models.

Conclusion

This study revealed a novel pathway, miR-346/Bax axis, in the regulation of apoptosis in MIRI and which might be a new molecular mechanism and therapeutic target.

Bone marrow niche crosses paths with BMPs: a road to protection and persistence in CML

Chronic myeloid leukaemia (CML) is a paradigm of precision medicine, being one of the first cancers to be treated with targeted therapy. This has revolutionised CML therapy and patient outcome, with high survival rates. However, this now means an ever-increasing number of patients are living with the disease on life-long tyrosine kinase inhibitor (TKI) therapy, with most patients anticipated to have near normal life expectancy. Unfortunately, in a significant number of patients, TKIs are not curative. This low-level disease persistence suggests that despite a molecularly targeted therapeutic approach, there are BCR-ABL1-independent mechanisms exploited to sustain the survival of a small cell population of leukaemic stem cells (LSCs). In CML, LSCs display many features akin to haemopoietic stem cells, namely quiescence, self-renewal and the ability to produce mature progeny, this all occurs through intrinsic and extrinsic signals within the specialised microenvironment of the bone marrow (BM) niche. One important avenue of investigation in CML is how the disease highjacks the BM, thereby remodelling this microenvironment to create a niche, which enables LSC persistence and resistance to TKI treatment. In this review, we explore how changes in growth factor levels, in particular, the bone morphogenetic proteins (BMPs) and pro-inflammatory cytokines, impact on cell behaviour, extracellular matrix deposition and bone remodelling in CML. We also discuss the challenges in targeting LSCs and the potential of dual targeting using combination therapies against BMP receptors and BCR-ABL1.

Role of miR-199a-5p in osteoblast differentiation by targeting TET2

OBJECTIVE

miR-199a-5p was increased during osteoblast differentiation, which may target and regulate TET2, a gene attracted a lot of attention in the osteoblast differentiation in the past few years. However, the role of miR-199a-5p in osteoblast differentiation by targeting TET2 is not established.

METHODS

The correlation between miR-199a-5p and TET2 was verified through dual luciferase reporter assay, and their expressions in human bone marrow stromal cells (hBMSCs) during the osteoblast differentiation were detected. hBMSCs were transfected with TET2 siRNA, miR-199a-5p mimic or/and TET2 CRISPR activation plasmid., and then prepared for the induction of osteoblast differentiation, followed by alkaline phosphatase (ALP) and alizarin red staining, qRT-PCR and Western blotting. In vivo, ovariectomized (OVX) mice were injected with agomir-miR-199a-5p, antagomiR-199a-5p or/and TET2 siRNA to calculate the BMD and BV/TV ratio of mice, as well as to measure the expressions of osteogenesis-related genes in bone tissues.

RESULTS

A gradual increase of miR-199a-5p was observed in hBMSCs during the induction of osteoblast differentiation, while TET2 expression was decreased. Besides, miR-199a-5p was reduced in the bone tissue of OVX mice, while TET2 was up-regulated. In addition, overexpression of miR-199a-5p and inhibition of TET2 augmented ALP activity in hBMSCs, with the enhanced calcification and the up-regulated expressions of Runx2, OSX and OCN, which also increased the quality of bone in OVX mice accompanying the enhancement BV/TV ratio, BMD and osteogenesis-related genes.

CONCLUSION

MiR-199a-5p may promote the osteoblast differentiation and prevent OVX-induced osteoporosis by targeting TET2.

Cytokines and Bone: Osteoimmunology

Cytokines and hematopoietic growth factors have traditionally been thought of as regulators of the development and function of immune and blood cells. However, an ever-expanding number of these factors have been discovered to have major effects on bone cells and the development of the skeleton in health and disease (Table 1). In addition, several cytokines have been directly linked to the development of osteoporosis in both animal models and in patients. In order to understand the mechanisms regulating bone cells and how this may be dysregulated in disease states, it is necessary to appreciate the diverse effects that cytokines and inflammation have on osteoblasts, osteoclasts, and bone mass. This chapter provides a broad overview of this topic with extensive references so that, if desired, readers can access specific references to delve into individual topics in greater detail.

The shift in the balance between osteoblastogenesis and adipogenesis of mesenchymal stem cells mediated by glucocorticoid receptor

Mesenchymal stem cells (MSCs) are multipotent cells capable of differentiating into several tissues, such as bone, cartilage, and fat. Glucocorticoids affect a variety of biological processes such as proliferation, differentiation, and apoptosis of various cell types, including osteoblasts, adipocytes, or chondrocytes. Glucocorticoids exert their function by binding to the glucocorticoid receptor (GR). Physiological concentrations of glucocorticoids stimulate osteoblast proliferation and promote osteogenic differentiation of MSCs. However, pharmacological concentrations of glucocorticoids can not only induce apoptosis of osteoblasts and osteocytes but can also reduce proliferation and inhibit the differentiation of osteoprogenitor cells. Several signaling pathways, including the Wnt, TGFβ/BMP superfamily and Notch signaling pathways, transcription factors, post-transcriptional regulators, and other regulators, regulate osteoblastogenesis and adipogenesis of MSCs mediated by GR. These signaling pathways target key transcription factors, such as Runx2 and TAZ for osteogenesis and PPARγ and C/EBPs for adipogenesis. Glucocorticoid-induced osteonecrosis and osteoporosis are caused by various factors including dysfunction of bone marrow MSCs. Transplantation of MSCs is valuable in regenerative medicine for the treatment of osteonecrosis of the femoral head, osteoporosis, osteogenesis imperfecta, and other skeletal disorders. However, the mechanism of inducing MSCs to differentiate toward the osteogenic lineage is the key to an efficient treatment. Thus, a better understanding of the molecular mechanisms behind the imbalance between GR-mediated osteoblastogenesis and adipogenesis of MSCs would not only help us to identify the pathogenic causes of glucocorticoid-induced osteonecrosis and osteoporosis but also promote future clinical applications for stem cell-based tissue engineering and regenerative medicine. Here, we primarily review the signaling mechanisms involved in adipogenesis and osteogenesis mediated by GR and discuss the factors that control the adipo-osteogenic balance.

MiR-216a alleviates LPS-induced acute lung injury via regulating JAK2/STAT3 and NF-κB signaling

MicroRNAs (miRNAs) play an important role in the progression of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Till now, little is known about the role of miR-216a in ALI/ARDS. In this study, patients with ARDS exhibited significantly higher interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels than healthy controls (P < 0.01). However, miR-216a expression in patients with ARDS was significantly lower than healthy controls (P < 0.05), and negatively correlated with 28-day survival rate. Similar effects were observed in LPS-treated mice and A549 cells. MiR-216a over-expression reduced LPS-induced IL-1β, IL-6 and TNF-α levels, and ameliorated lung permeability, and prolonged overall survival of ALI mice. Further, miR-216a over-expression inhibited LPS-induced apoptosis and autophagy. In addition, the janus kinase-2 (JAK2) was a direct target of miR-216a. Silencing of JAK2 partially aggravated miR-216a-inhibited inflammation injury. Besides, miR-216a obviously decreased the expressions of phosphorylated signal transducer and the activator of transcription 3 (p-STAT3), p-p56, and p-IκBα. In conclusion, miR-216a alleviates LPS-induced inflammatory injury via regulating JAK2/STAT3 and NF-κB signaling.

Milagro F, Sánchez J, de la Garza AL, Castro H. miRNAs and Novel Food Compounds Related to the Browning Process

Obesity prevalence is rapidly increasing worldwide. With the discovery of brown adipose tissue (BAT) in adult humans, BAT activation has emerged as a potential strategy for increasing energy expenditure. Recently, the presence of a third type of fat, referred to as beige or brite (brown in white), has been recognized to be present in certain kinds of white adipose tissue (WAT) depots. It has been suggested that WAT can undergo the process of browning in response to stimuli that induce and enhance the expression of thermogenesis: a metabolic feature typically associated with BAT. MicroRNAs (miRNAs) are small transcriptional regulators that control gene expression in a variety of tissues, including WAT and BAT. Likewise, it was shown that several food compounds could influence miRNAs associated with browning, thus, potentially contributing to the management of excessive adipose tissue accumulation (obesity) through specific nutritional and dietetic approaches. Therefore, this has created significant excitement towards the development of a promising dietary strategy to promote browning/beiging in WAT to potentially contribute to combat the growing epidemic of obesity. For this reason, we summarize the current knowledge about miRNAs and food compounds that could be applied in promoting adipose browning, as well as the cellular mechanisms involved.

MicroRNA-21 promotes bone reconstruction in maxillary bone defects

BACKGROUND

Bone reconstruction of the maxillary bone defects is an urgent issue due to its functional and aesthetic influence. MicroRNAs (miRNAs) are a class of non-coding RNAs that function in diverse biological and pathological processes. Recently, microRNA-21 (miR-21) was reported to play significant roles in bone formation, suggesting that miR-21 can be novel biomarker and therapeutic target for bone remodelling and skeletal diseases. However, the role of miR-21 in maxillary bone defects remains unclear.

OBJECTIVE AND METHODS

This study aimed to investigate the effect of miR-21 on the bone reconstruction by inducing maxillary bone defects in wild-type (WT) and miR-21 knockout (miR-21-KO) mice and explore these mice as maxillary bone defect models.

RESULTS

Micro-computed tomography (micro-CT) and histochemistry showed that the miR-21-KO mice had reduced bone reformation ability compared with the WT mice. The expression levels of alkaline phosphatase (ALP) and osteocalcin (OCN) were dramatically decreased in the miR-21-KO mice. In addition, injection of miR-21 agomir intra-peritoneally into miR-21-KO mice (miR-21-KO+ agomir) following the maxillary bone defects surgery displayed a significantly enhanced bone formation -promoting ability, which indicated that miR-21 agomir could ameliorate maxillary bone defects in miR-21-KO mice in vivo. Furthermore, immunohistochemistry suggested that ALP and OCN expressions were prominently increased in miR-21-KO+ agomir mice.

CONCLUSION

These findings demonstrated that miR-21 deficiency impaired bone reformation and miR-21 contributed to the bone reconstruction of the maxillary bone defects. The evidence also supported the use of WT and miR-21-KO mice as maxillary bone defect models for further research.

MiR-128-3p mediates TNF-α-induced inflammatory responses by regulating Sirt1 expression in bone marrow mesenchymal stem cells

Tumor Necrosis Factor α (TNF-α), a multifunctional pro-inflammatory cytokine, is produced by macrophages/monocytes during acute inflammation, and plays a critical role in orchestrating the cytokine cascade in various inflammatory diseases. Previous studies demonstrated that TNF-α induces inflammatory responses in bone marrow mesenchymal stem cells (BMSCs) transplantation, leading to unsatisfactory effects and limit the clinical use of BMSCs. MicroRNAs are reported to involve in inflammation by regulating the expression of their targets in inflammatory response pathway. However, whether microRNAs mediate TNF-α-induced inflammatory responses in BMSCs remains elusive. Here, we found that TNF-α treatment induced an inflammatory response by increasing the levels of key inflammatory mediators, including IL-6, IL-1β, matrix metalloproteinase 9 (MMP9) and monocyte chemotactic protein-1 (MCP-1) in BMSCs. Moreover, real-time PCR result showed dramatically up-regulation of miR-128-3p after exposure to TNF-α. Interestingly, miR-128-3p over-expression exacerbated the TNF-α-induced inflammatory response, while suppression of miR-128-3p effectively eliminated the inflammatory response in BMSCs. Bioinformatic analysis identified sirtuin 1 is a direct target of miR-128-3p. Up-regulation of sirtuin 1 induced by resveratrol also diminished the TNF-α-induced inflammatory response in BMSCs. Altogether, our results indicated that miR-128-3p targets sirtuin 1 to mediate the TNF-α-induced inflammatory response in BMSCs, which may provide new strategies to protect against inflammatory-dependent impairments in BMSCs.

The cross-talk between adipokines and miRNAs in health and obesity-mediated diseases

BACKGROUND

Multiple studies have revealed a direct correlation between obesity and the development of multiple comorbidities, including metabolic diseases, cardiovascular disorders, chronic inflammatory disease, and cancers. However, the molecular mechanism underlying the link between obesity and the progression of these diseases is not completely understood. Adipokines are factors that are secreted by adipocytes and play a key role in whole body homeostasis. Collaboratively, miRNAs are suggested to have key functions in the development of obesity and obesity-related disorders. Based on recently emerging evidence, obesity leads to the dysregulation of both adipokines and obesity-related miRNAs. In the present study, we described the correlations between obesity and its related diseases that are mediated by the mutual regulatory effects of adipokines and miRNAs.

METHODS

We reviewed current knowledge of the modulatory effects of adipokines on miRNAs activity and their relevant functions in pathological conditions and vice versa.

RESULTS

Our research reveals the ability of adipokines and miRNAs to control the expression and activity of the other class of molecules, and their effects on obesity-related diseases.

CONCLUSIONS

This study may help researchers develop a roadmap for future investigations and provide opportunities to develop new therapeutic and diagnostic methods for treating obesity-related diseases.

Let-7f-5p regulates TGFBR1 in glucocorticoid-inhibited osteoblast differentiation and ameliorates glucocorticoid-induced bone loss

Previous studies indicated that let-7 enhances osteogenesis and bone formation of human adipose-derived mesenchymal stem cells (MSCs). We also have confirmed that let-7f-5p expression was upregulated during osteoblast differentiation in rat bone marrow-derived MSCs (BMSCs) and was downregulated in the vertebrae of patients with glucocorticoid (GC)-induced osteoporosis (GIOP). The study was performed to determine the role of let-7f-5p in GC-inhibited osteogenic differentiation of murine BMSCs in vitro and in GIOP in vivo. Here, we report that dexamethasone (Dex) inhibited osteogenic differentiation of BMSCs and let-7f-5p expression, while increasing the expression of transforming growth factor beta receptor 1 (TGFBR1), a direct target of let-7f-5p during osteoblast differentiation under Dex conditions. In addition, let-7f-5p promoted osteogenic differentiation of BMSCs, as indicated by the promotion of alkaline phosphatase (ALP) staining and activity, Von Kossa staining, and osteogenic marker expression (Runx2,Osx, Alp, and Ocn), but decreased TGFBR1 expression in the presence of Dex. However, overexpression of TGFBR1 reversed the upregulation of let-7f-5p during Dex-treated osteoblast differentiation. Knockdown of TGFBR1 reversed the effect of let-7f-5p downregulation during Dex-treated osteogenic differentiation of BMSCs. We also found that glucocorticoid receptor (GR) mediated transcriptional silencing of let-7f-5p and its knockdown enhanced Dex-inhibited osteogenic differentiation. Further, when injected in vivo, agomiR-let-7f-5p significantly reversed bone loss induced by Dex, as well as increased osteogenic marker expression (Runx2, Osx, Alp, and Ocn) and decreased TGFBR1 expression in bone extracts. These findings indicated that the regulatory axis of GR/let-7f-5p/TGFBR1 may be important for Dex-inhibited osteoblast differentiation and that let-7f-5p may be a useful therapeutic target for GIOP.

Roles for miRNAs in osteogenic differentiation of bone marrow mesenchymal stem cells

Bone marrow mesenchymal stem cells (BMSCs), which were first discovered in bone marrow, are capable of differentiating into osteoblasts, chondrocytes, fat cells, and even myoblasts, and are considered multipotent cells. As a result of their potential for multipotential differentiation, self-renewal, immune regulation, and other effects, BMSCs have become an important source of seed cells for gene therapy, tissue engineering, cell replacement therapy, and regenerative medicine. MicroRNA (miRNA) is a highly conserved type of endogenous non-protein-encoding RNA of about 19-25 nucleotides in length, whose transcription process is independent of other genes. Generally, miRNA plays roles in regulating cell proliferation, differentiation, apoptosis, and development by binding to the 3' untranslated region of target mRNAs, whereby they can degrade or induce translational silencing. Although miRNAs play a regulatory role in various metabolic processes, they are not translated into proteins. Several studies have shown that miRNAs play an important role in the osteogenic differentiation of BMSCs. Herein, we describe in-depth studies of roles for miRNAs during the osteogenic differentiation of BMSCs, as they provide new theoretical and experimental rationales for bone tissue engineering and clinical treatment.

microRNA-196a promotes osteogenic differentiation and inhibit adipogenic differentiation of adipose stem cells via regulating β-catenin pathway

microRNAs play important roles in proliferation and differentiation of stem cells, but mechanisms by which microRNAs regulate osteogenic or adipogenic differentiation of adipose stem cells (ASCs) are still poorly understood. In the present study, results showed up-regulation of microRNA-196a was able to promote the osteogenic differentiation of ACSs, but down-regulation of microRNA-196a induced adipogenic differentiation. Further investigation indicated microRNA-196a could regulate Wnt signaling pathway to affect osteogenic or adipogenic differentiation of ASCs, addition of Wnt agonist 1 was able to reverse the down-regulated osteogenic differentiation of ASCs caused by microRNA-196a deficiency and inhibition of Wnt signaling pathway with XAV939 promoted the adipogenic differentiation of ASCs. Taken together, microRNA-196a may regulate Wnt signaling pathway to promote the osteogenic differentiation and inhibit the adipogenic differentiation of ASCs.

Effects of leukemia inhibitory factor receptor on the adipogenic differentiation of human bone marrow mesenchymal stem cells

Leukemia inhibitory factor (LIF) modulates various biological processes. Although previous studies have described the effects of LIF on adipocyte differentiation, the role of LIF receptor (LIFR) on adipocyte differentiation remains unclear. Using reverse transcription‑quantitative PCR (RT‑qPCR), LIFR expression was demonstrated to increase during adipogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs), indicating that LIFR may be involved in this process. To further evaluate the association between LIFR and adipogenic differentiation, lentivirus‑mediated LIFR knockdown was performed in hMSCs. Cells were divided into two groups: Negative control group and LIFR‑knockdown group. During the adipogenic differentiation process, intracellular lipid accumulation was assessed with Oil Red O staining at various time points (days 3, 6 and 9). Additionally, the mRNA and protein expression levels of LIF, LIFR and three molecular indicators of adipogenesis, peroxisome proliferator‑activated receptor γ (PPARγ), CCAAT enhancer binding protein α (C/EBPα) and fatty acid binding protein 4 (FABP4/aP2), were assessed by RT‑qPCR and western blotting. The culture supernatant was collected to evaluate the concentration of LIF using ELISA. The present results suggested that LIFR expression progressively increased during adipogenic differentiation of hMSCs. Conversely, LIFR knockdown significantly suppressed this process. Additionally, PPARγ, C/EBPα and aP2 were inhibited following LIFR knockdown. In contrast with LIFR, the expression levels of LIF were significantly decreased after the initiation of adipogenic differentiation. Therefore, the expression levels of LIF and LIFR exhibited opposite trends. Collectively, the present results suggested that LIFR promoted adipogenic differentiation, whereas LIF may negatively regulate this process.

Normalization strategies differently affect circulating miRNA profile associated with the training status

MicroRNAs are fine regulators of the whole-body adaptive response but their use as biomarkers is limited by the lack of standardized pre- and post-analytical procedures. This work aimed to compare different normalization approaches for RT-qPCR data analyses, in order to identify the most reliable and reproducible method to analyze circulating miRNA expression profiles in sedentary and highly-trained subjects. As the physically active status is known to affect miRNA expression, they could be effective biomarkers of the homeostatic response. Following RNA extraction from plasma, a panel of 179 miRNAs was assayed by RT-qPCR and quantified by applying different normalization strategies based on endogenous miRNAs and exogenous oligonucleotides. hsa-miR-320d was found as the most appropriate reference miRNA in reducing the technical variability among the experimental replicates and, hence, in highlighting the inter-cohorts differences. Our data showed an association between the physically active status and specific skeletal muscle- and bone-associated circulating miRNAs profiles, revealing that established epigenetic modifications affect the baseline physiological status of these tissues. Since different normalization strategies led to different outputs, in order to avoid misleading interpretation of data, we remark the importance of the accurate choice of the most reliable normalization method in every experimental setting.

Interplay between microRNAs and Wnt, transforming growth factor-β, and bone morphogenic protein signaling pathways promote osteoblastic differentiation of mesenchymal stem cells

Osteoblasts are terminally differentiated cells with mesenchymal origins, known to possess pivotal roles in sustaining bone microstructure and homeostasis. These cells are implicated in the pathophysiology of various bone disorders, especially osteoporosis. Over the last few decades, strategies to impede bone resorption, principally by bisphosphonates, have been mainstay of treatment of osteoporosis; however, in recent years more attention has been drawn on bone-forming approaches for managing osteoporosis. MicroRNAs (miRNAs) are a broad category of noncoding short sequence RNA fragments that posttranscriptionally regulate the expression of diverse functional and structural genes in a negative manner. An accumulating body of evidence signifies that miRNAs direct mesenchymal stem cells toward osteoblast differentiation and bone formation through bone morphogenic protein, transforming growth factor-β, and Wnt signaling pathways. MiRNAs are regarded as excellent future therapeutic candidates because of their small size and ease of delivery into the cells. Considering their novel therapeutic significance, this review discusses the main miRNAs contributing to the anabolic aspects of bone formation and illustrates their interactions with corresponding signaling pathways involved in osteoblastic differentiation.