Functional profiling reveals critical role for miRNA in differentiation of human mesenchymal stem cells. PLoS One. 2009;4:e5605. [PMID: 19440384 PMCID: PMC2680014 DOI: 10.1371/journal.pone.0005605]

Delivery of miRNAs Using Porous Silicon Nanoparticles Incorporated into 3D Hydrogels Enhances MSC Osteogenesis by Modulation of Fatty Acid Signaling and Silicon Degradation

Strategies incorporating mesenchymal stromal cells (MSC), hydrogels and osteoinductive signals offer promise for bone repair. Osteoinductive signals such as growth factors face challenges in clinical translation due to their high cost, low stability and immunogenicity leading to interest in microRNAs as a simple, inexpensive and powerful alternative. The selection of appropriate miRNA candidates and their efficient delivery must be optimised to make this a reality. This study evaluated pro-osteogenic miRNAs and used porous silicon nanoparticles modified with polyamidoamine dendrimers (PAMAM-pSiNP) to deliver these to MSC encapsulated within gelatin-PEG hydrogels. miR-29b-3p, miR-101-3p and miR-125b-5p are strongly pro-osteogenic and are shown to target FASN and ELOVL4 in the fatty acid biosynthesis pathway to modulate MSC osteogenesis. Hydrogel delivery of miRNA:PAMAM-pSiNP complexes enhanced transfection compared to 2D. The osteogenic potential of hBMSC in hydrogels with miR125b:PAMAM-pSiNP complexes is evaluated. Importantly, a dual-effect on osteogenesis occurred, with miRNAs increasing expression of alkaline phosphatase (ALP) and Runt-related transcription factor 2 (RUNX2) whilst the pSiNPs enhanced mineralisation, likely via degradation into silicic acid. Overall, this work presents insights into the role of miRNAs and fatty acid signalling in osteogenesis, providing future targets to improve bone formation and a promising system to enhance bone tissue engineering.

Transforming growth factor-beta superfamily regulates mesenchymal stem cell osteogenic differentiation: A microRNA linking

The ability to differentiate into cells of different lineages, such as bone cells, is the principal value of adult mesenchymal stem cells (MSCs), which can be used with the final aim of regenerating damaged tissue. Due to its potential use and importance in regenerative medicine and tissue engineering, several questions have been raised regarding the molecular mechanisms of MSC differentiation. As one of the crucial mediators in organism development, the transforming growth factor-beta (TGF-β) superfamily directs MSCs' commitment to selecting differentiation pathways. This review aims to give an overview of the current knowledge on the mechanisms of the TGF-β superfamily in MSCs bone differentiation, with additional insight into the mutual regulation of microRNAs and TGF-β in osteogenesis.

Dual scaffold delivery of miR-210 mimic and miR-16 inhibitor enhances angiogenesis and osteogenesis to accelerate bone healing

Angiogenesis is critical for successful bone repair, and interestingly, miR-210 and miR-16 possess counter-active targets involved in both angiogenesis and osteogenesis: miR-210 acts as an activator by silencing EFNA3 & AcvR1b, while miR-16 inhibits both pathways by silencing VEGF & Smad5. It was thus hypothesized that dual delivery of both a miR-210 mimic and a miR-16 inhibitor from a collagen-nanohydroxyapatite scaffold system may hold significant potential for bone repair. Therefore, this systems potential to rapidly accelerate bone repair by directing enhanced angiogenic-osteogenic coupling in host cells in a rat calvarial defect model at a very early 4 week timepoint was assessed. In vitro, the treatment significantly enhanced angiogenic-osteogenic coupling of human mesenchymal stem cells, with enhanced calcium deposition after just 10 days in 2D and 14 days on scaffolds. In vivo, these dual-miRNA loaded scaffolds showed more than double bone volume and vessel recruitment increased 2.3 fold over the miRNA-free scaffolds. Overall, this study demonstrates the successful development of a dual-miRNA mimic/inhibitor scaffold for enhanced in vivo bone repair for the first time, and the possibility of extending this 'off-the-shelf' platform system to applications beyond bone offers immense potential to impact a myriad of other tissue engineering areas. STATEMENT OF SIGNIFICANCE: miRNAs have potential as a new class of bone healing therapeutics as they can enhance the regenerative capacity of bone-forming cells. However, angiogenic-osteogenic coupling is critical for successful bone repair. Therefore, this study harnesses the delivery of miR-210, known to be an activator of both angiogenesis and osteogenesis, and miR-16 inhibitor, as miR-16 is known to inhibit both pathways, from a collagen-nanohydroxyapatite scaffold system to rapidly enhance osteogenesis in vitro and bone repair in vivo in a rat calvarial defect model. Overall, it describes the successful development of the first dual-miRNA mimic/inhibitor scaffold for enhanced in vivo bone repair. This 'off-the-shelf' platform system offers immense potential to extend beyond bone applications and impact a myriad of other tissue engineering areas.

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.

Reverse transcription-free digital-quantitative-PCR for microRNA analysis

MicroRNAs (miRNAs) are non-coding RNA sequences that regulate many biological processes and have become central targets of biomedical research. However, their naturally low abundances in biological samples necessitates the development of sensitive analytical techniques to conduct routine miRNA measurements in research laboratories. Digital PCR has the potential to meet this need because of its single-molecule detection capabilities, but PCR analyses of miRNAs are slowed by the ligation and reverse transcription steps first required to prepare samples. This report describes the development of a method to rapidly quantify miRNA in digital microwell arrays using base-stacking digital-quantitative-PCR (BS-dqPCR). BS-dqPCR expedites miRNA measurements by eliminating the need for ligation and reverse transcription steps, which reduces the time and cost compared to conventional miRNA PCR analyses. Under standard PCR thermocycling conditions, digital signals from miRNA samples were lower than expected, while signals from blanks were high. Therefore, a novel asymmetric thermocycling program was developed that maximized on-target signal from miRNA while minimizing non-specific amplification. The analytical response of BS-dqPCR was then evaluated over a range of miRNA concentrations. The digital PCR dimension increased in signal with increasing miRNA copy numbers. When the digital signal saturated, the quantitative PCR dimension readily discerned miRNA copy number differences. Overall, BS-dqPCR provides rapid, high-sensitivity measurements of miRNA over a wide dynamic range, which demonstrates its utility for routine miRNA analyses.

Transit Amplifying Cells (TACs): a still not fully understood cell population

Maintenance of tissue homeostasis and tissue regeneration after an insult are essential functions of adult stem cells (SCs). In adult tissues, SCs proliferate at a very slow rate within "stem cell niches", but, during tissue development and regeneration, before giving rise to differentiated cells, they give rise to multipotent and highly proliferative cells, known as transit-amplifying cells (TACs). Although differences exist in diverse tissues, TACs are not only a transitory phase from SCs to post-mitotic cells, but they also actively control proliferation and number of their ancestor SCs and proliferation and differentiation of their progeny toward tissue specific functional cells. Autocrine signals and negative and positive feedback and feedforward paracrine signals play a major role in these controls. In the present review we will consider the generation and the role played by TACs during development and regeneration of lining epithelia characterized by a high turnover including epidermis and hair follicles, ocular epithelial surfaces, and intestinal mucosa. A comparison between these different tissues will be made. There are some genes and molecular pathways whose expression and activation are common to most TACs regardless their tissue of origin. These include, among others, Wnt, Notch, Hedgehog and BMP pathways. However, the response to these molecular signals can vary in TACs of different tissues. Secondly, we will consider cultured cells derived from tissues of mesodermal origin and widely adopted for cell therapy treatments. These include mesenchymal stem cells and dedifferentiated chondrocytes. The possible correlation between cell dedifferentiation and reversion to a transit amplifying cell stage will be discussed.

miRNAs, Mesenchymal Stromal Cells and Major Neoplastic and Inflammatory Skin Diseases: A Page Being Written: A Systematic Review

Micro RNAs (miRNAs) are a type of non-coding RNA (ncRNA) and typically interact with specific target mRNAs through complementary base pairing, affecting their translation and/or stability. MiRNAs regulate nearly all cellular functions, including the cell fate of mesenchymal stromal cells (MSCs). It is now accepted that various pathologies arise at the stem level, and, in this scenario, the role played by miRNAs in the fate of MSCs becomes of primary concern. Here we have considered the existing literature in the field of miRNAs, MSCs and skin diseases, classified as inflammatory (such as psoriasis and atopic dermatitis-AD) and neoplastic (melanoma and non-melanoma-skin-cancer including squamous cell and basal cell carcinoma) diseases. In this scoping review article, the evidence recovered indicates that this topic has attracted attention, but it is still a matter of opinion. A protocol for this review was registered in PROSPERO with the registration number "CRD42023420245". According to the different skin disorders and to the specific cellular mechanisms considered (cancer stem cells, extracellular vesicles, inflammation), miRNAs may play a pro- or anti-inflammatory, as well as a tumor suppressive, or supporting, role, indicating a complex regulation of their function. It is evident that the mode of action of miRNAs is more than a switch on-off, and all the observed effects of their dysregulated expression must be checked in a detailed analysis of the targeted proteins. The involvement of miRNAs has been studied mainly for squamous cell carcinoma and melanoma, and much less in psoriasis and AD; different mechanisms have been considered, such as miRNAs included in extracellular vesicles derived both from MSCs or tumor cells, miRNAs involved in cancer stem cells formation, up to miRNAs as candidates to be new therapeutic tools.

Analysis of MIR27A (rs11671784) Variant Association with Systemic Lupus Erythematous

Multiple microRNAs (miRs) are associated with systemic autoimmune disease susceptibility/phenotype, including systemic lupus erythematosus (SLE). With this work, we aimed to unravel the association of the miR-27a gene (MIR27A) rs11671784G/A variant with SLE risk/severity. One-hundred sixty-three adult patients with SLE and matched controls were included. A TaqMan allelic discrimination assay was applied for MIR27A genotyping. Logistic regression models were run to test the association with SLE susceptibility/risk. Genotyping of 326 participants revealed that the heterozygote form was the most common genotype among the study cohort, accounting for 72% of the population (n = 234), while A/A and G/G represented 15% (n = 49) and 13% (n = 43), respectively. Similarly, the most prevalent genotype among cases was the A/G genotype, which was present in approximately 93.3% of cases (n = 152). In contrast, only eight and three patients had A/A and G/G genotypes, respectively. The MIR27A rs11671784 variant conferred protection against the development of SLE in several genetic models, including heterozygous (G/A vs. A/A; OR = 0.10, 95% CI = 0.05–0.23), dominant (G/A + G/G vs. AA; OR = 0.15, 95% CI = 0.07–0.34), and overdominant (G/A vs. A/A + G/G; OR = 0.07, 95% CI = 0.04–0.14) models. However, the G/G genotype was associated with increased SLE risk in the recessive model (G/G vs. A/A+ G/G; OR = 17.34, 95% CI = 5.24–57.38). Furthermore, the variant showed significant associations with musculoskeletal and mucocutaneous manifestations in the patient cohort (p = 0.035 and 0.009, respectively) and platelet and white blood cell counts (p = 0.034 and 0.049, respectively). In conclusion, the MIR27A rs11671784 variant showed a potentially significant association with SLE susceptibility/risk in the studied population. Larger-scale studies on multiethnic populations are recommended to verify the results.

Evaluation of osteogenic induction potency of miR-27a-3p in adipose tissue-derived human mesenchymal stem cells (AD-hMSCs)

BACKGROUND

Bone tissue as a dynamic tissue is able to repair its minor injuries, however, sometimes the repair cannot be completed by itself due to the size of lesion. In such cases, the best treatment could be bone tissue engineering. The use of stem cells in skeletal disorders to repair bone defects has created bright prospects. On the other hand, changes in the expression level of microRNAs (miRs) can lead to the commitment of mesenchymal stem cells (MSCs) to cell lineage. Many studies reported that post-transcriptional regulations by miRNAs are involved in all stages of osteoblast differentiation.

METHOD

After the preparing adipose tissue-derived mesenchymal stem cells, the target cells from the third passage were cultured in two groups, transfected MSCs with miR-27a-3p (DM.C + P) and control group. In different times, 7 and 14 days after culture, differentiation of these cells into osteoblast were measured using various techniques including the ALP test and calcium content test, Alizarin Red staining, Immunocytochemistry technique (ICC). Also, the relative expression of bone differentiation marker genes including Osteonectin (ON), Osteocalcin (OC), RUNX Family Transcription Factor 2 (RUNX2), Collagen type I alpha 1 (COL1) was investigated by real-time RT PCR.

RESULTS

In comparison with control groups, overexpression of miR-27a-3p in transfected cells resulted in a significant increase in the expression of bone markers genes (ON, OC, RUNX2, COL1), alkaline phosphatase (ALP) activity, and calcium content (p < 0.05). In addition, the results obtained from ICC technique showed that osteocalcin protein is expressed at the surface of bone cells. Furthermore, the expression of APC, as a target of miR-27a-3p, decreased in transfected cells.

CONCLUSION

Our data suggest that miR-27a-3p may positively regulates adipose tissue-derived mesenchymal stem cell differentiation into bone by targeting APC and activating the Wnt/b-catenin pathway.

Mechanosensitive miR-99b mediates the regulatory effect of matrix stiffness on bone marrow mesenchymal stem cell fate both in vitro and in vivo

Mechanical signals from extracellular matrix stiffness are important cues that regulate the proliferation and differentiation of bone marrow mesenchymal stem cells (BMSCs). However, the incorporation of BMSCs into soft hydrogels and the dominance of soft matrices for BMSC growth and differentiation limit the directed differentiation of BMSCs incorporated into hydrogels for tissue engineering, especially osteogenesis. Here, we found that the expression of miR-99b increased with increasing hydrogel stiffness and that miR-99b regulated the proliferation and differentiation of BMSCs seeded on the surface of substrates with different stiffnesses. Furthermore, miR-99b significantly promoted the migration of BMSCs in 3D hydrogels. Mechanistically, we demonstrated that matrix stiffness-sensitive miR-99b targets the mammalian target of the rapamycin signaling pathway to regulate the adipogenic and osteogenic differentiation of BMSCs. In addition, by modulating the expression of miR-99b, the osteogenic differentiation of BMSCs in soft 3D hydrogels was promoted. Consistently, the flexible BMSC-GelMA hydrogel transfected with miR-99b significantly promoted bone regeneration in the rat calvarial defect area. These results suggest that miR-99b plays a key role in the mechanotransduction and phenotypic transformation of BMSCs and may inspire new tissue engineering applications with MSCs as key components.

miRNA induced 3D bioprinted-heterotypic osteochondral interface

The engineering of osteochondral interfaces remains a challenge. MicroRNAs (miRs) have emerged as significant tools to regulate the differentiation and proliferation of osteogenic and chondrogenic formation in the human musculoskeletal system. Here, we describe a novel approach to osteochondral reconstruction based on the three-dimensional (3D) bioprinting of miR-transfected adipose-derived stem cell (ADSC) spheroids to produce a heterotypic interface that addresses the intrinsic limitations of the traditional approach to inducing zonal differentiation via the use of diffusible cytokines. We evaluated the delivery of miR-148b for osteogenic differentiation and the codelivery of miR-140 and miR-21 for the chondrogenic differentiation of ADSC spheroids. Our results demonstrated that miR-transfected ADSC spheroids exhibited upregulated expression of osteogenic and chondrogenic differentiation related gene and protein markers, and enhanced mineralization and cell proliferation compared to spheroids differentiated using a commercially-available differentiation medium. Upon confirmation of the osteogenic and chondrogenic potential of miR-transfected ADSC spheroids, using aspiration-assisted bioprinting, these spheroids were 3D bioprinted into a dual-layer heterotypic osteochondral interface with a stratified arrangement of distinct osteogenic and chondrogenic zones. The proposed approach holds great promise for the biofabrication of stratified tissues, not only for the osteochondral interfaces presented in this work, but also for other composite tissues and tissue interfaces, such as, but not limited to, the bone-tendon-muscle interface and craniofacial tissues.

miR-30b-5p inhibits osteoblast differentiation through targeting BCL6

Human bone marrow mesenchymal stem cells (hBMSCs) are attractive candidates for new therapies to improve bone regeneration and repair. This study was to identify the function of the miR-30b-5p/BCL6 axis in osteogenic differentiation of hBMSCs. Realtime-quantitative PCR (RT-qPCR) and Western blotting were used to measure the relative expression of ALP, OCN, RUNX2, miR-30b-5p, and BCL6 during osteogenic differentiation of hBMSCs. The relationship between miR-30b-5p and BCL6 in hBMSCs was identified using dual-luciferase reporter system and RNA pull-down assay. Alizarin red S staining (ARS) was used to detect the calcium nodules in hBMSCs. We found that the expression of miR-30b-5p was downregulated, whereas that of BCL6 was upregulated during osteogenic differentiation of hBMSCs. Downregulating miR-30b-5p enhanced the expression of OCN, RUNX2, and ALP, and promoted calcium deposition. Conversely, transfection with si-BCL6 had the opposite effect that it inhibited osteogenic differentiation. However, the inhibitory effect of si-BCL6 was abrogated by miR-30b-5p inhibitor. miR-30b-5p inhibits the osteogenic differentiation of hBMSCs by targeting BCL6.

Upregulation of miR-489-3p attenuates cerebral ischemia/reperfusion injury by targeting histone deacetylase 2 (HDAC2)

Cerebral ischemia/reperfusion (I/R) injury is the continuation and deterioration of ischemic injury, and there are no effective treatment strategies for this condition. It has been reported that microRNAs (miRNAs) are considered as potential targets to protect the brain against I/R injury. Previous studies have shown that miR-489-3p plays a vital role in regulating apoptosis of neurons. miR-489-3p is considered as a potential target to protect the brain against I/R injury-induced neuron apoptosis. This study aimed to explore the molecular mechanism of miR-489-3p in protection against cerebral I/R injury. A rat model with cerebral I/R injury was established using the MCAO method. The cell model was constructed using the oxygen‑glucose deprivation (OGD) method. The expression of miR-489-3p was detected by qRT-PCR. The expression of HDAC2 was detected by western blot assay and immunofluorescence assay. Cell apoptosis was evaluated by flow cytometry and TUNEL staining assay. The relationship between miR-489-3p and HDAC2 was determined by bioinformatics analysis and luciferase reporter assay. Rescue experiments were performed to investigate the mechanism of the miR-489-3p/HDAC2 axis. miR-489-39 was significantly downregulated, while HDAC2 was upregulated during cerebral I/R injury both in vitro and in vivo. Upregulation of miR-489-3p obviously attenuated cerebral I/R injury by increasing PC12 cell viability, reducing LDH release, and inhibiting cell apoptosis. HDAC2 was identified as a direct target of miR-489-3p. Silencing of HDAC2 showed a neuroprotective effect against OGD/R injury in vitro. Overexpression of HDAC2 significantly attenuated the protective effects of miR-489-3p mimics on cell injury in vitro. Our results revealed that the upregulation of miR-489-3p attenuated cerebral I/R injury by negatively regulating HDAC2.

Kynurenine induces an age-related phenotype in bone marrow stromal cells

Advanced age is one of the important contributing factors for musculoskeletal deterioration. Although the exact mechanism behind this degeneration is unknown, it has been previously established that nutritional signaling plays a vital role in musculoskeletal pathophysiology. Our group established the vital role of the essential amino acid, tryptophan, in aging musculoskeletal health. With advanced age, inflammatory factors activate indoleamine 2,3-dioxygenase (IDO1) and accumulate excessive intermediate tryptophan metabolites such as Kynurenine (KYN). With age, Kynurenine accumulates and suppresses osteogenic differentiation, impairs autophagy, promotes early senescence, and alters cellular bioenergetics of bone marrow stem cells. Recent studies have shown that Kynurenine negatively impacts bone marrow stromal cells (BMSCs) and, consequently, promotes bone loss. Overall, understanding the mechanism behind BMSCs losing their ability for osteogenic differentiation can provide insight into the prevention of osteoporosis and the development of targeted therapies. Therefore, in this article, we review Kynurenine and how it plays a vital role in BMSC dysfunction and bone loss with age.

Osteoimmunological insights into the pathogenesis of ankylosing spondylitis

Ankylosing spondylitis (AS) is inflammatory arthritis predominantly affecting the spine, which is involved in the disorders of both immune and skeletal systems. The exact pathogenesis of AS is not fully understood. Osteoimmunology is a new subject of study in inflammatory arthritis, in particular the pathogenic events involved in the cross-regulation of both skeletal and immune systems. In this review, we discuss osteoimmunological and pathological changes of AS in the spine that are characterized by altered osteogenesis and osteolytic bone destruction, accompanied by the changes of the immune system. It was revealed that bone cells like mesenchymal stem cells, osteoblast, and osteoclast in crossing talking with immune cells such as T cells, B cells coregulate to the pathogenesis of AS. Further, an array of cytokines and molecules expressed by both skeletal and immune systems contribute to these complex interplays. Understanding the cellular and molecular mechanisms underlying the pathogenesis of AS will lay a foundation for the exploration of the potential new treatment to AS.

Topological Analysis of Regulatory Networks Reveals Functionally Key Genes and miRNAs Involved in the Differentiation of Mesenchymal Stem Cells

Background

The details of molecular mechanisms underlying the differentiation of Mesenchymal Stem Cells (MSCs) into specific lineages are not well understood.

Objectives

We aimed to construct the interactome network and topology analysis of bone marrow mesenchymal stem cell of CAGE data. Applying the enrichment results, we wanted to introduce the common genes and hub-microRNA and hub-genes of these giant network.

Materials and Methods

In this study, we constructed gene regulatory networks for each non-mesenchymal cell lineage according to their gene expression profiles obtained from FANTOM5 database. The putative interactions of TF-gene and protein-protein were determined using TRED, STRING, HPRD and GeneMANIA servers. In parallel, a regulatory network including corresponding miRNAs and total differentially expressed genes (DEGs) was constructed for each cell lineage.

Results

The results indicated that analysis of networks' topology can significantly distinguish the hub regulatory genes and miRNAs involved in the differentiation of MSCs. The functional annotation of identified hub genes and miRNAs revealed that several signal transduction pathways i.e. AKT, WNT and TGFβ and cell proliferation related pathways play a pivotal role in the regulation of MSCs differentiation. We also classified cell lineages into two groups based on their predicted miRNA profiles.

Conclusions

In conclusion, we found a number of hub genes and miRNAs which seem to have key regulatory functions during differentiation of MSCs. Our results also introduce a number of new regulatory genes and miRNAs which can be considered as the new candidates for genetic manipulation of MSCs in vitro.

MiR-17-3p inhibits osteoblast differentiation by downregulating Sox6 expression

Osteoporosis and osteoarthritis are orthopedic disorders that affect millions of elderly people worldwide; stimulation of bone formation is a potential therapeutic strategy for the treatment of these conditions. As the only bone‐forming cells, osteoblasts play a key role in bone reconstruction. The microRNA miR‐17‐3p is downregulated during osteogenic differentiation of human bone marrow mesenchymal stem cells, but its precise role in this process is unknown. Here, we investigated the role of miR‐17‐3p in osteoblast differentiation. An in vitro model of osteogenesis was established by treating MC3T3‐E1 murine preosteoblast cells with bone morphogenetic protein 2 (BMP2). The expression of miR‐17‐3p in BMP2‐induced MC3T3‐E1 cells was detected by reverse transcription‐quantitative PCR, and its effects on cells transfected with miR‐17‐3p mimic or inhibitor were evaluated by Alizarin Red staining, alkaline phosphatase (ALP) activity assay, and by detection of osteoblast markers including the ALP, collagen type I α1 chain, and osteopontin genes. Bioinformatics analysis was carried out to identify putative target genes of miR‐17‐3p, and the luciferase reporter assay was used for functional validation. Rescue experiments were performed to determine whether SRY‐box transcription factor 6 (Sox6) plays a role in the regulation of osteoblast differentiation by miR‐17‐3p. We report that miR‐17‐3p was downregulated upon BMP2‐induced osteoblast differentiation in MC3T3‐E1 cells, and this was accompanied by decreased differentiation and mineralization, ALP activity, and expression of osteogenesis‐related genes. Sox6 was confirmed to be a target gene of miR‐17‐3p in osteoblasts, and the inhibitory effect of miR‐17‐3p on osteoblast differentiation was observed to occur via Sox6. These results suggest the existence of a novel mechanism underlying miRNA‐mediated regulation of osteogenesis, which has potential implications for the treatment of orthopedic disorders.

Kynurenine Pathway in Chronic Kidney Disease: What’s Old, What’s New, and What’s Next?

Impaired kidney function and increased inflammatory process occurring in the course of Chronic Kidney Disease (CKD) contribute to the development of complex amino-acid alterations. The essential amino-acid tryptophan (TRP) undergoes extensive metabolism along several pathways, resulting in the production of many biologically active compounds. The results of many studies have shown that its metabolism via the kynurenine pathway is potently increased in the course of CKD. Metabolites of this pathway exhibit differential, sometimes opposite, roles in several biological processes. Their accumulation in the course of CKD may induce oxidative cell damage which stimulates inflammatory processes. They can also modulate the activity of numerous cellular signaling pathways through activation of the aryl hydrocarbon receptor, leading to the disruption of homeostasis of various organs. As a result, they can contribute to the development of the systemic disorders accompanying the course of chronic renal failure. This review gathers and systematizes reports concerning the knowledge connecting the kynurenine pathway metabolites to systemic disorders accompanying the development of CKD.

SNHG14 induces osteogenic differentiation of human stromal (mesenchymal) stem cells in vitro by downregulating miR-2861

BACKGROUND

The differentiation of human stromal (mesenchymal) stem cells (hMSCs) is a critical procedure for the development of osteoblast. SNHG14 is a newly discovered lncRNA that has been barely studied. Our preliminary experiments showed that SNHG14 may be dysregulated in the differentiation of hMSCs. In this study, we focused on elucidating the relationships among SNGH14, miR-2861, and osteoblastic differentiation of hMSCs.

METHOD

To investigate the roles of SNHG14 and miR2861 in hMSCs differentiation, qRT-PCR, luciferase activity, cell transfections, the detections of ALP activity, and Alizarin Red staining were performed.

RESULT

We found that the expression of SNHG14 was enhanced, while the expression of miR-2861 was suppressed in serum and hMSCs from patients with osteoporosis. SNHG14 could target miR-2861, and shSNHG14 suppressed osteoblast differentiation of hMSC. MiR-2861 suppressed osteoblast differentiation of hMSC. In addition, the effects of SNHG14 on osteoblast differentiation of hMSC were attenuated by miR-2861.

CONCLUSION

In conclusion, our experimental data showed that the induction effects of SNHG14 on osteoblast differentiation of hMSC were attenuated by miR-2861. SNHG14 could induce osteogenic differentiation of hMSC in vitro by targeting miR-2861.

miR-489-3p inhibits proliferation and migration of bladder cancer cells through downregulation of histone deacetylase 2

Since human bladder cancer (BC) is a common malignancy of the urinary system with poor prognosis, it is crucial to clarify the molecular mechanisms of BC development and progression. To the best of our knowledge, the current study demonstrated for the first time that miR-489-3p suppressed BC cell-derived tumor growth in vivo via the downregulation of histone deacetylase 2 (HDAC2). According to the results, expression levels of miR-489-3p were lower in BC tissues compared with corresponding normal tissues. Expression of miR-489-3p mimics in BC-derived T24 and 5637 cells resulted in a significant reduction in proliferation and migration rates. Furthermore, bioinformatics analyses indicated that HDAC2 may be a potential downstream target of miR-489-3p. In contrast to miR-489-3p, HDAC2 was expressed at higher levels in BC tissues compared with corresponding normal tissues. Additionally, small interfering RNA-mediated knockdown of HDAC2 caused a marked decrease in the proliferation and migration rates of T24 and 5637 cells. Consistent with these observations, expression of miR-489-3p mimics attenuated the growth of xenograft tumors arising from T24 cells and resulted in HDAC2 downregulation. In conclusion, the results of the current study indicated that the miR-489-3p/HDAC2 axis serves a role in the development and/or the progression of BC and may be a potential molecular target for the development of a novel strategy to treat patients with BC.

MiR-132/212 promotes the growth of precartilaginous stem cells (PCSCs) by regulating Ihh/PTHrP signaling pathway

Precartilaginous stem cells (PCSCs) are adult stem cells that can initiate chondrocytes and bone development. In the present study, we explored whether miR-132/212 was involved in the proliferation of PCSCs via Hedgehog signaling pathway. PCSCs were isolated and purified with the fibroblast growth factor receptor-3 (FGFR-3) antibody. Cell viability, DNA synthesis and apoptosis were measured using MTT, BrdU and flow cytometric analysis. The mRNA and protein expression were detected by real-time PCR and Western blot, respectively. The target gene for miR-132/212 was validated by luciferase reporter assay. Results showed that transfection with miR-132/212 mimic significantly increased cell viability and DNA synthesis, and inhibited apoptosis of PCSCs. By contrast, miR-132/212 inhibitor could suppress growth and promote apoptosis of PCSCs. Luciferase reporter assays indicated that transfection of miR-132/212 led to a marked reduction of luciferase activity, but had no effect on PTCH1 3′-UTR mutated fragment, suggesting that Patched1 (PTCH1) is a target of miR-132/212. Furthermore, treatment with miR-132/212 mimics obviously increased the protein expression of Indian hedgehog (Ihh) and parathyroid hormone related protein (PTHrP), which was decreased after treatment with Hedgehog signaling inhibitor, cyclopamine. We also found that inhibition of Ihh/PTHrP signaling by cyclopamine significantly suppressed growth and DNA synthesis, and induced apoptosis in PCSCs. These findings demonstrate that miR-132/212 promotes growth and inhibits apoptosis in PCSCs by regulating PTCH1-mediated Ihh/PTHrP pathway, suggesting that miR-132/212 cluster might serve as a novel target for bone diseases.

Nanocomposites drug delivery systems for the healing of bone fractures

The skeletal system is fundamental for the structure and support of the body consisting of bones, cartilage, and connective tissues. Poor fracture healing is a chief clinical problem leading to disability, extended hospital stays and huge financial liability. Even though most fractures are cured using standard clinical methods, about 10% of fractures are delayed or non-union. Despite decades of progress, the bone-targeted delivery system is still restricted due to the distinctive anatomical bone features. Recently, various novel nanocomposite systems have been designed for the cell-specific targeting of bone, enhancing drug solubility, improving drug stability and inhibiting drug degradation so that it can reach its target site without being removed in the systemic circulation. Such targeting systems could consist of biological compounds i.e. bone marrow stem cells (BMSc), growth factors, RNAi, parathyroid hormone or synthetic compounds, i.e. bisphosphonates (BPs) and calcium phosphate cement. Hydrogels and nanoparticles are also being employed for fracture healing. In this review, we discussed the normal mechanism of bone healing and all the possible drug delivery systems being employed for the healing of the bone fracture.

Accumulation of kynurenine elevates oxidative stress and alters microRNA profile in human bone marrow stromal cells

Kynurenine, a metabolite of tryptophan breakdown, has been shown to increase with age, and plays a vital role in a number of age-related pathophysiological changes, including bone loss. Accumulation of kynurenine in bone marrow stromal cells (BMSCs) has been associated with a decrease in cell proliferation and differentiation, though the exact mechanism by which kynurenine mediates these changes is poorly understood. MiRNAs have been shown to regulate BMSC function, and accumulation of kynurenine may alter the miRNA expression profile of BMSCs. The aim of this study was to identify differentially expressed miRNAs in human BMSCs in response to treatment with kynurenine, and correlate miRNAs function in BMSCs biology through bioinformatics analysis. Human BMSCs were cultured and treated with and without kynurenine, and subsequent miRNA isolation was performed. MiRNA array was performed to identify differentially expressed miRNA. Microarray analysis identified 50 up-regulated, and 36 down-regulated miRNAs in kynurenine-treated BMSC cultures. Differentially expressed miRNA included miR-1281, miR-330-3p, let-7f-5p, and miR-493-5p, which are important for BMSC proliferation and differentiation. KEGG analysis found up-regulated miRNA targeting glutathione metabolism, a pathway critical for removing oxidative species. Our data support that the kynurenine dependent degenerative effect is partially due to changes in the miRNA profile of BMSCs.

Label-free proteomic analysis reveals large dynamic changes to the cellular proteome upon expression of the miRNA-23a-27a-24-2 microRNA cluster

In deciphering the regulatory networks of gene expression controlled by the small non-coding RNAs known as microRNAs (miRNAs), a major challenge has been with the identification of the true mRNA targets by these RNAs within the context of the enormous numbers of predicted targets for each of these small RNAs. To facilitate the system-wide identification of miRNA targets, a variety of system wide methods, such as proteomics, have been implemented. Here we describe the utilization of quantitative label-free proteomics and bioinformatics to identify the most significant changes to the proteome upon expression of the miR-23a-27a-24-2 miRNA cluster. In light of recent work leading to the hypothesis that only the most pronounced regulatory events by miRNAs may be physiologically relevant, our data reveal that label-free analysis circumvents the limitations of proteomic labeling techniques that limit the maximum differences that can be quantified. The result of our analysis identifies a series of novel candidate targets that are reduced in abundance by more than an order of magnitude upon the expression of the miR-23a-27a-24-2 cluster.

Combinatorial Delivery of miRNA-Nanoparticle Conjugates in Human Adipose Stem Cells for Amplified Osteogenesis

It is becoming more apparent in tissue engineering applications that fine temporal control of multiple therapeutics is desirable to modulate progenitor cell fate and function. Herein, the independent temporal control of the co-delivery of miR-148b and miR-21 mimic plasmonic nanoparticle conjugates to induce osteogenic differentiation of human adipose stem cells (hASCs), in a de novo fashion, is described. By applying a thermally labile retro-Diels-Alder caging and linkage chemistry, these miRNAs can be triggered to de-cage serially with discrete control of activation times. The method relies on illumination of the nanoparticles at their resonant wavelengths to generate sufficient local heating and trigger the untethering of the Diels-Alder cycloadduct. Characterization of the photothermal release using fluorophore-tagged miRNA mimics in vitro is carried out with fluorescence measurements, second harmonic generation, and confocal imaging. Osteogenesis of hASCs from the sequential co-delivery of miR-21 and miR-148b mimics is assessed using xylenol orange and alizarin red staining of deposited minerals, and quantitative polymerase chain reaction for gene expression of osteogenic markers. The results demonstrate that sequential miRNA mimic activation results in upregulation of osteogenic markers and mineralization relative to miR-148b alone, and co-activation of miR-148b and miR-21 at the same time.

Collagen-infilled 3D printed scaffolds loaded with miR-148b-transfected bone marrow stem cells improve calvarial bone regeneration in rats

Differentiation of progenitors in a controlled environment improves the repair of critical-sized calvarial bone defects; however, integrating micro RNA (miRNA) therapy with 3D printed scaffolds still remains a challenge for craniofacial reconstruction. In this study, we aimed to engineer three-dimensional (3D) printed hybrid scaffolds as a new ex situ miR-148b expressing delivery system for osteogenic induction of rat bone marrow stem cells (rBMSCs) in vitro, and also in vivo in critical-sized rat calvarial defects. miR-148b-transfected rBMSCs underwent early differentiation in collagen-infilled 3D printed hybrid scaffolds, expressing significant levels of osteogenic markers compared to non-transfected rBMSCs, as confirmed by gene expression and immunohistochemical staining. Furthermore, after eight weeks of implantation, micro-computed tomography, histology and immunohistochemical staining results indicated that scaffolds loaded with miR-148b-transfected rBMSCs improved bone regeneration considerably compared to the scaffolds loaded with non-transfected rBMSCs and facilitated near-complete repair of critical-sized calvarial defects. In conclusion, our results demonstrate that collagen-infilled 3D printed scaffolds serve as an effective system for miRNA transfected progenitor cells, which has a promising potential for stimulating osteogenesis and calvarial bone repair.

Dysregulated MicroRNA Fingerprints and Methylation Patterns in Hepatocellular Carcinoma, Cancer Stem Cells, and Mesenchymal Stem Cells

Hepatocellular carcinoma (HCC) is one of the top causes of cancer mortality worldwide. Although HCC has been researched extensively, there is still a need for novel and effective therapeutic interventions. There is substantial evidence that initiation of carcinogenesis in liver cirrhosis, a leading cause of HCC, is mediated by cancer stem cells (CSCs). CSCs were also shown to be responsible for relapse and chemoresistance in several cancers, including HCC. MicroRNAs (miRNAs) constitute important epigenetic markers that regulate carcinogenesis by acting post-transcriptionally on mRNAs, contributing to the progression of HCC. We have previously shown that co-culture of cancer cells with mesenchymal stem cells (MSCs) could induce the reprogramming of MSCs into CSC-like cells. In this review, we evaluate the available data concerning the epigenetic regulation of miRNAs through methylation and the possible role of this regulation in stem cell and somatic reprogramming in HCC.

Overexpression of MicroRNA-148b-3p stimulates osteogenesis of human bone marrow-derived mesenchymal stem cells: the role of MicroRNA-148b-3p in osteogenesis

Background

Mesenchymal stem cells (MSCs) are attractive choices in regenerative medicine and can be genetically modified to obtain better results in therapeutics. Bone development and metabolism are controlled by various factors including microRNAs (miRs) interference, which are small non-coding endogenous RNAs.

Methods

In the current study, the effects of forced miR-148b expression was evaluated on osteogenic activity. Human bone marrow-derived mesenchymal stem cells (BM-MSCs) were transduced with bicistronic lentiviral vector encoding hsa-miR-148b-3p or -5p and the enhanced green fluorescent protein. Fourteen days post-transduction, immunostaining as well as Western blotting were used to analyze osteogenesis.

Results

Overexpression of miR-148b-3p increased the osteogenic differentiation of human BM-MSCs as demonstrated by anenhancement of mineralized nodular formation and an increase in the levels of osteoblastic differentiation biomarkers, alkaline phosphatase and collagen type I.

Conclusions

Since lentivirally overexpressed miR-148b-3p increased osteogenic differentiation capability of BM-MSCs, this miR could be applied as a therapeutic modulator to optimize bone function.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0854-3) contains supplementary material, which is available to authorized users.

Enhanced Transfection of Human Mesenchymal Stem Cells Using a Hyaluronic Acid/Calcium Phosphate Hybrid Gene Delivery System

Human mesenchymal stem cells (hMSCs) show enormous potential in regenerative medicine and tissue engineering. However, current use of hMSCs in clinics is still limited because there is no appropriate way to control their behavior in vivo, such as differentiation to a desired cell type. Genetic modification may provide an opportunity to control the cells in an active manner. One of the major hurdles for genetic manipulation of hMSCs is the lack of an efficient and safe gene delivery system. Herein, biocompatible calcium phosphate (CaP)-based nanoparticles stabilized with a catechol-derivatized hyaluronic acid (dopa-HA) conjugate were used as a carrier for gene transfection to hMSCs for improved differentiation. Owing to the specific interactions between HA and CD44 of bone marrow-derived hMSCs, dopa-HA/CaP showed significantly higher transfection in hMSCs than branched polyethylenimine (bPEI, MW 25 kDa) with no cytotoxicity. The co-delivery of a plasmid DNA encoding bone morphogenetic protein 2 (BMP-2 pDNA) and micro RNA 148b (miRNA-148b) by dopa-HA/CaP achieved significantly improved osteogenic differentiation of hMSCs.

miR-148b-3p, miR-337-5p and miR-423-5p expression in alveolar ridge atrophy and their roles in the proliferation and apoptosis of OMMSCs

MicroRNAs (miRNAs/miRs) have key roles in various physiological and pathological processes by regulating the expression of specific genes. The identification of miRNAs involved in bone metabolism may provide insight into the expression of genes associated with the development of alveolar ridge atrophy. In the present study, the miRNA expression profiles in alveolar ridge atrophy and normal tissue samples were investigated by miRNA microarray analysis. Among the 52 differentially expressed miRNAs identified, the expression levels of 20 selected miRNAs in the alveolar ridge atrophy and normal tissue samples were verified by reverse transcription-quantitative polymerase chain reaction. The results indicated that the expression levels of 11 miRNAs were significantly different between alveolar ridge atrophy and normal tissue samples; however, only three of them (miR-148b-3p, miR-337-5p and miR-423-5p) were previously reported to be involved in bone metabolism. In vitro, miR-148b-3p, miR-337-5p and miR-423-5p mimics promoted the proliferation and inhibited apoptosis of bone marrow mesenchymal stem cells from orofacial bone (OMMSCs), while antisense inhibitors of these miRNAs had the opposite effect. In conclusion, the present study indicated that these miRNAs are involved in the pathogenesis of alveolar ridge atrophy. miR-148b-3p, miR-337-5p and miR-423-5p promote the proliferation of OMMSCs and inhibit their apoptosis. The present results provide a novel perspective for understanding the pathogenesis of alveolar ridge atrophy.

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.

Small non-coding RNA landscape of extracellular vesicles from human stem cells

Extracellular vesicles (EVs) are reported to be involved in stem cell maintenance, self-renewal, and differentiation. Due to their bioactive cargoes influencing cell fate and function, interest in EVs in regenerative medicine has rapidly increased. EV-derived small non-coding RNA mimic the functions of the parent stem cells, regulating the maintenance and differentiation of stem cells, controlling the intercellular regulation of gene expression, and eventually affecting the cell fate. In this study, we used RNA sequencing to provide a comprehensive overview of the expression profiles of small non-coding transcripts carried by the EVs derived from human adipose tissue stromal/stem cells (AT-MSCs) and human pluripotent stem cells (hPSCs), both human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSC). Both hPSCs and AT-MSCs were characterized and their EVs were extracted using standard protocols. Small non-coding RNA sequencing from EVs showed that hPSCs and AT-MSCs showed distinct profiles, unique for each stem cell source. Interestingly, in hPSCs, most abundant miRNAs were from specific miRNA families regulating pluripotency, reprogramming and differentiation (miR-17-92, mir-200, miR-302/367, miR-371/373, CM19 microRNA cluster). For the AT-MSCs, the highly expressed miRNAs were found to be regulating osteogenesis (let-7/98, miR-10/100, miR-125, miR-196, miR-199, miR-615-3p, mir-22-3p, mir-24-3p, mir-27a-3p, mir-193b-5p, mir-195-3p). Additionally, abundant small nuclear and nucleolar RNA were detected in hPSCs, whereas Y- and tRNA were found in AT-MSCs. Identification of EV-miRNA and non-coding RNA signatures released by these stem cells will provide clues towards understanding their role in intracellular communication, and well as their roles in maintaining the stem cell niche.

Epigenetics and bone diseases

Owing to the development of new technologies, the epigenome, a second dimensional method for genome analysis has emerged. Epigenetic mechanisms, including DNA methylation, histone modifications and noncoding RNAs, regulate gene expression without changing the genetic sequence. These epigenetic mechanisms normally modulate gene expression, trans-generational effects and inherited expression states in various biological processes. Abnormal epigenetic patterns typically cause pathological conditions, including cancers, age-related diseases, and specific cartilage and bone diseases. Facing the rapidly developing epigenetic field, we reviewed epigenetic mechanisms and their involvement with the skeletal system and their role in skeletal development, homeostasis and degeneration. Finally, we discuss the prospects for the future of epigenetics.

Inhibition of microRNA-138 enhances bone formation in multiple myeloma bone marrow niche

Myeloma bone disease is a devastating complication of multiple myeloma (MM) and is caused by dysregulation of bone remodeling processes in the bone marrow microenvironment. Previous studies showed that microRNA-138 (miR-138) is a negative regulator of osteogenic differentiation of mesenchymal stromal cells (MSCs) and that inhibiting its function enhances bone formation in vitro. In this study, we explored the role of miR-138 in myeloma bone disease and evaluated the potential of systemically delivered locked nucleic acid (LNA)-modified anti-miR-138 oligonucleotides in suppressing myeloma bone disease. We showed that expression of miR-138 was significantly increased in MSCs from MM patients (MM-MSCs) and myeloma cells compared to those from healthy subjects. Furthermore, inhibition of miR-138 resulted in enhanced osteogenic differentiation of MM-MSCs in vitro and increased the number of endosteal osteoblastic lineage cells (OBCs) and bone formation rate in mouse models of myeloma bone disease. RNA sequencing of the OBCs identified TRPS1 and SULF2 as potential miR-138 targets that were de-repressed in anti-miR-138-treated mice. In summary, these data indicate that inhibition of miR-138 enhances bone formation in MM and that pharmacological inhibition of miR-138 could represent a new therapeutic strategy for treatment of myeloma bone disease.

Titanium implant functionalized with antimiR-138 delivered cell sheet for enhanced peri-implant bone formation and vascularization

Patients with compromised bone conditions still suffer the problem of deficient osseointegration during dental implant treatment. Developing mesenchymal stem cell (MSC) sheet functionalized titanium implant with proper inductive cue to promote osteogenesis and angiogenesis coupling shall be a good solution. In the present study, the antimiR-138 delivered MSC sheet is used to functionalize the Ti implant. The cell sheet can well integrate with the Ti implant to form the MSC sheet-implant complex (MSIC). The antimiR-138 delivered MSIC shows greatly improved osteogenesis and angiogenesis coupling both in vitro and in vivo. In vitro, the antimiR-138 delivered MSIC significantly promotes the expression of endogenous osteogenesis and angiogenesis related genes and proteins, alkaline phosphatase activity, extracellular matrix mineralization and collagen secretion compared to the antimiR-control and the nothing delivered control. The in vivo ectopic implantation assay uncovers the robust vascularized bone formation of the antimiR-138 delivered MSIC. The antimiR-138 delivered MSIC with promoted osteogenesis and angiogenesis coupling is anticipated to lead to rigid osseointegration in the compromised bone conditions.

D-2-Hydroxyglutarate Is Necessary and Sufficient for Isocitrate Dehydrogenase 1 Mutant-Induced MIR148A Promoter Methylation

Mutant isocitrate dehydrogenase (IDH) 1/2 converts α-ketoglutarate (α-KG) to D-2 hydroxyglutarate (D-2-HG), a putative oncometabolite that can inhibit α-KG-dependent enzymes, including ten-eleven translocation methylcytosine dioxygenase (TET) DNA demethylases. We recently established that miRNAs are components of the IDH1 mutant-associated glioma CpG island methylator phenotype (G-CIMP) and specifically identified MIR148A as a tumor-suppressive miRNA within G-CIMP. However, the precise mechanism by which mutant IDH induces hypermethylation of MIR148A and other G-CIMP promoters remains to be elucidated. In this study, we demonstrate that treatment with exogenous D-2-HG induces MIR148A promoter methylation and transcriptional silencing in human embryonic kidney 293T (293T) cells and primary normal human astrocytes. Conversely, we show that the development of MIR148A promoter methylation in mutant IDH1-overexpressing 293T cells is abrogated via treatment with C227, an inhibitor of mutant IDH1 generation of D-2-HG. Using dot blot assays for global assessment of 5-hydroxymethylcytosine (5-hmC), we show that D-2-HG treatment reduces 5-hmC levels, whereas C227 treatment increases 5-hmC levels, strongly suggesting TET inhibition by D-2-HG. Moreover, we show that withdrawal of D-2-HG treatment reverses methylation with an associated increase in MIR148A transcript levels and transient generation of 5-hmC. We also demonstrate that RNA polymerase II binds endogenously to the predicted promoter region of MIR148A, validating the hypothesis that its transcription is driven by an independent promoter.Implications: Establishment of D-2-HG as a necessary and sufficient intermediate by which mutant IDH1 induces CpG island methylation of MIR148A will help with understanding the efficacy of selective mutant IDH1 inhibitors in the clinic. Mol Cancer Res; 16(6); 947-60. ©2018 AACR.

Development of controlled drug delivery systems for bone fracture-targeted therapeutic delivery: A review

Impaired fracture healing is a major clinical problem that can lead to patient disability, prolonged hospitalization, and significant financial burden. Although the majority of fractures heal using standard clinical practices, approximately 10% suffer from delayed unions or non-unions. A wide range of factors contribute to the risk for nonunions including internal factors, such as patient age, gender, and comorbidities, and external factors, such as the location and extent of injury. Current clinical approaches to treat nonunions include bone grafts and low-intensity pulsed ultrasound (LIPUS), which realizes clinical success only to select patients due to limitations including donor morbidities (grafts) and necessity of fracture reduction (LIPUS), respectively. To date, therapeutic approaches for bone regeneration rely heavily on protein-based growth factors such as INFUSE, an FDA-approved scaffold for delivery of bone morphogenetic protein 2 (BMP-2). Small molecule modulators and RNAi therapeutics are under development to circumvent challenges associated with traditional growth factors. While preclinical studies has shown promise, drug delivery has become a major hurdle stalling clinical translation. Therefore, this review overviews current therapies employed to stimulate fracture healing pre-clinically and clinically, including a focus on drug delivery systems for growth factors, parathyroid hormone (PTH), small molecules, and RNAi therapeutics, as well as recent advances and future promise of fracture-targeted drug delivery.

Mirna biogenesis pathway is differentially regulated during adipose derived stromal/stem cell differentiation

Stromal/stem cell differentiation is controlled by a vast array of regulatory mechanisms. Included within these are methods of mRNA gene regulation that occur at the level of epigenetic, transcriptional, and/or posttranscriptional modifications. Current studies that evaluate the posttranscriptional regulation of mRNA demonstrate microRNAs (miRNAs) as key mediators of stem cell differentiation through the inhibition of mRNA translation. miRNA expression is enhanced during both adipogenic and osteogenic differentiation; however, the mechanism by which miRNA expression is altered during stem cell differentiation is less understood. Here we demonstrate for the first time that adipose-derived stromal/stem cells (ASCs) induced to an adipogenic or osteogenic lineage have differences in strand preference (-3p and -5p) for miRNAs originating from the same primary transcript. Furthermore, evaluation of miRNA expression in ASCs demonstrates alterations in both miRNA strand preference and 5'seed site heterogeneity. Additionally, we show that during stem cell differentiation there are alterations in expression of genes associated with the miRNA biogenesis pathway. Quantitative RT-PCR demonstrated changes in the Argonautes (AGO1-4), Drosha, and Dicer at intervals of ASC adipogenic and osteogenic differentiation compared to untreated ASCs. Specifically, we demonstrated altered expression of the AGOs occurring during both adipogenesis and osteogenesis, with osteogenesis increasing AGO1-4 expression and adipogenesis decreasing AGO1 gene and protein expression. These data demonstrate changes to components of the miRNA biogenesis pathway during stromal/stem cell differentiation. Identifying regulatory mechanisms for miRNA processing during ASC differentiation may lead to novel mechanisms for the manipulation of lineage differentiation of the ASC through the global regulation of miRNA as opposed to singular regulatory mechanisms.

Mechanically-sensitive miRNAs bias human mesenchymal stem cell fate via mTOR signalling

Mechanotransduction is a strong driver of mesenchymal stem cell (MSC) fate. In vitro, variations in matrix mechanics invoke changes in MSC proliferation, migration and differentiation. However, when incorporating MSCs within injectable, inherently soft hydrogels, this dominance over MSC response substantially limits our ability to couple the ease of application of hydrogels with efficiently directed MSC differentiation, especially in the case of bone generation. Here, we identify differential miRNA expression in response to varying hydrogel stiffness and RhoA activity. We show that modulation of miR-100-5p and miR-143-3p can be used to bias MSC fate and provide mechanistic insight by demonstrating convergence on mTOR signalling. By modulating these mechanosensitive miRNAs, we can enhance osteogenesis in a soft 3D hydrogel. The outcomes of this study provide new understanding of the mechanisms regulating MSC mechanotransduction and differentiation, but also a novel strategy with which to drive MSC fate and significantly impact MSC-based tissue-engineering applications.

Mesenchymal stem cell (MSC) fate can be mechanically regulated by substrate stiffness but this is difficult to control in a 3D hydrogel. Here the authors identify miRNAs that change expression in response to substrate stiffness and RhoA signalling and show that they can bias MSC fate in a 3D soft hydrogel.

Endogenous Stem Cells in Homeostasis and Aging

In almost all human tissues and organs, adult stem cells or tissue stem cells are present in a unique location, the so-called stem cell niche or its equivalent, continuously replenishing functional differentiated cells. Those endogenous stem cells can be expanded for cell therapeutics using ex vivo cell culture or recalled for tissue repair in situ through cell trafficking and homing. In the aging process, inefficiency in the endogenous stem cell-mediated healing mechanism can emerge from a variety of impairments that accumulate in the processes of stem cell self-renewal, function, differentiation capacity, and trafficking through cell autonomous intrinsic pathways (such as epigenetic alterations) or systemic extrinsic pathways. This review examines the homeostasis of endogenous stem cells, particularly bone marrow stem cells, and their dysregulation in disease and aging and discusses possible intervention strategies. Several systemic pro-aging and rejuvenating factors, recognized in heterochronic parabiosis or premature aging progeroid animal models, are reviewed as possible anti-aging pharmaceutical targets from the perspective of a healthy environment for endogenous stem cells. A variety of epigenetic modifications and chromosome architectures are reviewed as an intrinsic cellular pathway for aging and senescence. A gradual increase in inflammatory burden during aging is also reviewed. Finally, the tissue repair and anti-aging effects of Substance-P, a peptide stimulating stem cell trafficking from the bone marrow and modifying the inflammatory response, are discussed as a future anti-aging target.

Icariin possesses chondroprotective efficacy in a rat model of dexamethasone-induced cartilage injury through the activation of miR-206 targeting of cathepsin K

The present study aimed to investigate the articular cartilage and chondrocytes of dexamethasone (DXM)-induced cartilage injuries in rats in response to treatment with icariin, as well as the implicated molecular mechanism. Effects of icariin on bone metabolism and articular cartilage in experimental rats were investigated. Subsequently, the present study assessed dysregulated microRNA (miRNA) in the articular cartilage of experimental rats, and validated the significant miRNA and their targets. Finally, the effects of icariin on chondrocytes in experimental rats and the implicated molecular mechanism were explored. Quantitative polymerase chain reaction demonstrated that icariin significantly reversed DXM-induced bone degradation and stimulated bone regeneration. In addition, some notable changes in articular cartilage were also observed following continuous administration of icariin to DXM-treated rats, including enhanced cartilage area (revealed by safranin-O staining), substantial decrements in serum concentrations of deoxypyridinoline and C-terminal telopeptide of type II collagen, reduced expression of collagen type I and matrix metalloproteinase-13, as well as elevated expression of transforming growth factor-β. Furthermore, miR-206 was determined to be significantly upregulated in the icariin group compared with the DXM-treated group. A luciferase assay further validated cathepsin K as the target RNA of miR-206. Additionally, icariin (100 µM) facilitated the viability of chondrocytes and reduced apoptotic chondrocytes. More importantly, icariin (100 µM) not only abolished the inhibition effect of DXM on miR-206 expression in chondrocytes, but also eliminated the enhancing effect of DXM on cathepsin K expression. Overall, the present study identified icariin as a novel therapeutic agent in DXM-induced cartilage injury in rats, and revealed that the activation of miR-206 targeting of cathepsin K may be responsible for the chondroprotective efficacy of icariin.

The Effects of BMP-2, miR-31, miR-106a, and miR-148a on Osteogenic Differentiation of MSCs Derived from Amnion in Comparison with MSCs Derived from the Bone Marrow

Mesenchymal stromal cells (MSCs) offering valuable anticipations for the treatment of degenerative diseases. They can be found in many tissues including amnion. MSCs from amnion (AM-MSCs) can differentiate into osteoblast similar to that of bone marrow-derived MSCs (BM-MSCs). However, the ability is not much efficient compared to BM-MSCs. This study aimed to examine the effects of BMP-2 and miRNAs on osteogenic differentiation of AM-MSCs compared to those of BM-MSCs. The osteogenic differentiation capacity after miRNA treatment was assessed by ALP expression, ALP activity, and osteogenic marker gene expression. The results showed that the osteogenic differentiation capacity increased after BMP-2 treatment both in AM-MSCs and BM-MSCs. MiR-31, miR-106a, and miR-148a were downregulated during the osteogenic differentiation. After transfection with anti-miRNAs, ALP activity and osteogenic genes were increased over the time of differentiation. The data lead to the potential for using AM-MSCs as an alternative source for bone regeneration. Moreover, the information of miRNA expression and function during osteogenic differentiation may be useful for the development of new therapeutics or enhanced an in vitro culture technique required for stem cell-based therapies in the bone regeneration.

Small non-coding RNAs-based bone regulation and targeting therapeutic strategies

Small non-coding RNAs, which are 20-25 nucleotide ribonucleic acids, have emerged as an important transformation in the biological evolution over almost three decades. microRNAs (miRNAs) and short interfering RNAs (siRNAs) are two significant categories of the small RNAs that exert important effects on bone endocrinology and skeletology. Therefore, clarifying the expression and function of these important molecules in bone endocrine physiology and pathology is of great significance for improving their potential therapeutic value for metabolism-associated bone diseases. In the present review, we highlight the recent advances made in understanding the function and molecular mechanism of these small non-coding RNAs in bone metabolism, especially their potentially therapeutic values in bone-related diseases.

The Potential of microRNAs for Stem Cell-based Therapy for Degenerative Skeletal Diseases

Purpose of Review

Degenerative skeletal disorders including osteoarthritis (OA) and osteoporosis (OP) are the result of attenuation of tissue regeneration and lead to painful conditions with limited treatment options. Preventative measures to limit the onset of OA and OP remain a significant unmet clinical need. MicroRNAs (miRNAs) are known to be involved in the differentiation of stem cells, and in combination with stem cell therapy could induce skeletal regeneration and potentially prevent OA and OP onset.

Recent Findings

The combination of stem cells and miRNA has been successful at regenerating the bone and cartilage in vivo. MiRNAs, including miR-146b known to be involved in chondrogenic differentiation, could provide innovative targets for stem cell-based therapy, for the repair of articular cartilage defects forestalling the onset of OA or in the generation of a stem cell-based therapy for OP.

Summary

This review discusses the combination of skeletal stem cells (SSCs) and candidate miRNAs for application in a cell-based therapy approach for skeletal regenerative medicine.

miR-148b Regulates Proliferation and Differentiation of Neural Stem Cells via Wnt/β-Catenin Signaling in Rat Ischemic Stroke Model

Stroke is the second leading cause of death worldwide. Stroke induced proliferation and differentiation of neural stem cells (NSCs) that have been proven to participate in ischemic brain repair. However, molecular mechanisms that regulate neurogenesis have not been fully investigated. MicroRNAs play an important role in the neurological repairing process and impact stroke recovery outcome. MiRNA-148b has been reported to regulate cell proliferation in tumor cells, but its role in NSCs after ischemic stroke remains unknown. Here, we found an overexpression of MiRNA-148b in subventricular zone (SVZ) of rat ischemic brain. In original cultured ischemic NSCs, transfection of MiRNA-148b mimic or inhibitor could suppress or enhance the expression of Wnt-1, β-catenin, and Cyclin D1, hence effected wnt/β-catenin signaling. MiRNA-148b inhibitor promoted NSCs proliferation and differentiation into newborn neural and astrocytes, and this action could be silenced with knockdown of Wnt-1. In middle cerebral artery occlusion (MCAo) rats, injection of MiRNA-148b inhibitor could reduce ischemic lesion volume and improve neurological function outcome. Collectively, our data suggest that MiRNA-148b suppressed wnt/β-catenin signaling attenuates proliferation and differentiation of neural stem cells, these findings shed new light on the role of MiRNA-148b in the recovery process during the stroke and contribute to the novel therapy strategy.

MicroRNAs expression profile in solid and unicystic ameloblastomas

OBJECTIVES

Odontogenic tumors (OT) represent a specific pathological category that includes some lesions with unpredictable biological behavior. Although most of these lesions are benign, some, such as the ameloblastoma, exhibit local aggressiveness and high recurrence rates. The most common types of ameloblastoma are the solid/multicystic (SA) and the unicystic ameloblastoma (UA); the latter considered a much less aggressive entity as compared to the SA. The microRNA system regulates the expression of many human genes while its deregulation has been associated with neoplastic development. The aim of the current study was to determine the expression profiles of microRNAs present in the two most common types of ameloblastomas.

MATERIAL & METHODS

MicroRNA expression profiles were assessed using TaqMan® Low Density Arrays (TLDAs) in 24 samples (8 SA, 8 UA and 8 control samples). The findings were validated using quantitative RTqPCR in an independent cohort of 19 SA, 8 UA and 19 dentigerous cysts as controls.

RESULTS

We identified 40 microRNAs differentially regulated in ameloblastomas, which are related to neoplastic development and differentiation, and with the osteogenic process. Further validation of the top ranked microRNAs revealed significant differences in the expression of 6 of them in relation to UA, 7 in relation to SA and 1 (miR-489) that was related to both types.

CONCLUSION

We identified a new microRNA signature for the ameloblastoma and for its main types, which may be useful to better understand the etiopathogenesis of this neoplasm. In addition, we identified a microRNA (miR-489) that is suggestive of differentiating among solid from unicystic ameloblastoma.