The epigenetic promotion of osteogenic differentiation of human adipose-derived stem cells by the genetic and chemical blockade of histone demethylase LSD1

Histone lysine demethylase 1A inhibitors, seclidemstat and tranylcypromine, induce astrocytogenesis in rat neural stem cells

Identifying the molecules that control neural stem cell (NSC) fate would revolutionize treatment strategies for neurodegenerative diseases. Histone lysine demethylase 1A (KDM1A) demethylates the mono- and di-methyl groups of histone 3 lysine 4 (H3K4) and H3K9 and plays an essential role in NSC proliferation. In this study, we investigated the effects of Seclidemstat (SP-2577), a reversible KDM1A inhibitor, and tranylcypromine (TCP), a monoamine oxidase inhibitor and recently known as an irreversible histone lysine demethylase 1A inhibitor, on NSCs. SP-2577 and TCP increased glial fibrillary acidic protein expression (GFAP), decreased βIII-tubulin (TUBB3) expression, and phosphorylated signal transducer and activator of transcription 3 (STAT3) in rat NSCs. SP-2577 and TCP enhanced the transcription of Gfap and reduced Tubb3 transcription. Furthermore, SP-2577 increased the transcription levels of interleukin-6 and leukemia inhibitory factor, while TCP induced the transcription level of fibroblast growth factor 2. Therefore, we show that the KDM1A inhibitors, SP-2577 and TCP, induce astrocytogenesis in rat NSCs. These findings suggest that KDM1A is a target for regulating NSCs fate and provide insights into the molecular mechanisms underlying neurodevelopmental processes and epigenetics.

miR-708-3p targetedly regulates LSD1 to promote osteoblast differentiation of hPDLSCs in periodontitis

Periodontitis (PD) is a multifactorial inflammatory disease associated with periodontopathic bacteria. Lysine-specific demethylase 1 (LSD1), a type of histone demethylase, has been implicated in the modulation of the inflammatory response process in oral diseases by binding to miRNA targets. This study investigates the molecular mechanisms by which miRNA binds to LSD1 and its subsequent effect on osteogenic differentiation. First, human periodontal ligament stem cells (hPDLSCs) were isolated, cultured, and characterized. These cells were then subjected to lipopolysaccharide (LPS) treatment to induce inflammation, after which osteogenic differentiation was initiated. qPCR and western blot were employed to monitor changes in LSD1 expression. Subsequently, LSD1 was silenced in hPDLSCs to evaluate its impact on osteogenic differentiation. Through bioinformatics and dual luciferase reporter assay, miR-708-3p was predicted and confirmed as a target miRNA of LSD1. Subsequently, miR-708-3p expression was assessed, and its role in hPDLSCs in PD was evaluated through overexpression. Using chromatin immunoprecipitation (ChIP) and western blot assay, we explored the potential regulation of osterix (OSX) transcription by miR-708-3p and LSD1 via di-methylated H3K4 (H3K4me2). Finally, we investigated the role of OSX in hPDLSCs. Following LPS treatment of hPDLSCs, the expression of LSD1 increased, but this trend was reversed upon the induction of osteogenic differentiation. Silencing LSD1 strengthened the osteogenic differentiation of hPDLSCs. miR-708-3p was found to directly bind to and negatively regulate LSD1, leading to the repression of OSX transcription through demethylation of H3K4me2. Moreover, overexpression of miR-708-3p was found to promote hPDLSCs osteogenic differentiation in inflammatory microenvironment. However, the protective effect was partially attenuated by reduced expression of OSX. Our findings indicate that miR-708-3p targetedly regulates LSD1 to enhance OSX transcription via H3K4me2 methylation, ultimately promoting hPDLSCs osteogenic differentiation.

Enriched H3K27Me3 on BMP4 suppresses the osteoblastic differentiation potential of BMSCs in diabetes mellitus

Diabetes mellitus has been widely acknowledged to have a negative effect on the osteoblastic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). However, the underlying epigenetic mechanisms associated with this process remain to be elucidated. The goal of the present study was to investigate the effect of diabetes mellitus on the osteoblastic differentiation of BMSCs and assess the role of histone methylation in the observed phenomena. The osteoblastic differentiation ability of BMSCs was shown to be decreased in diabetes mellitus, as indicated by alkaline phosphatase activity and the mRNA levels of osteoblast-related genes. Furthermore, diabetes mellitus caused an increased expression of the histone methylase EZH2 and the levels of H3K27Me3 and decreased the expression of the histone demethylase KDM6B, as demonstrated by qRT-PCR and western blotting. Furthermore, immunofluorescence staining suggested that both EZH2 and H3K27Me3 were primarily localized in the nucleus. In addition, chromatin immunoprecipitation assays indicated an increased presence of H3K27Me3 on the promoter region of the BMP4 gene. In summary, in the present study, we demonstrated that the osteoblastic differentiation of BMSCs is dramatically reduced in diabetes mellitus. In addition, upregulation of EZH2 expression and downregulation of KDM6B expression may not be enough to eliminate transcriptional repression mediated by H3K27Me3 on the promoter region of the BMP4 gene during the osteoblastic differentiation of BMSCs in diabetes mellitus.

The complex role of Rcor2: Regulates mesenchymal stromal cell differentiation in vitro but is dispensable in vivo

Recent research has revealed several important pathways of epigenetic regulation leading to transcriptional changes in bone cells. Rest Corepressor 2 (Rcor2) is a coregulator of Lysine-specific histone demethylase 1 (Lsd1), a demethylase linked to osteoblast activity, hematopoietic stem cell differentiation and malignancy of different neoplasms. However, the role of Rcor2 in osteoblast differentiation has not yet been examined in detail. We have previously shown that Rcor2 is highly expressed in mesenchymal stromal cells (MSC) and particularly in the osteoblastic lineage. The role of Rcor2 in osteoblastic differentiation in vitro was further characterized and we demonstrate here that lentiviral silencing of Rcor2 in MC3T3-E1 cells led to a decrease in osteoblast differentiation. This was indicated by decreased alkaline phosphatase and von Kossa stainings as well as by decreased expression of several osteoblast-related marker genes. RNA-sequencing of the Rcor2-downregulated MC3T3-E1 cells showed decreased repression of Rcor2 target genes, as well as significant upregulation of majority of the differentially expressed genes. While the heterozygous, global loss of Rcor2 in vivo did not lead to a detectable bone phenotype, conditional deletion of Rcor2 in limb-bud mesenchymal cells led to a moderate decrease in cortical bone volume. These findings were not accentuated by challenging bone formation by ovariectomy or tibial fracture. Furthermore, a global deletion of Rcor2 led to decreased white adipose tissue in vivo and decreased the capacity of primary cells to differentiate into adipocytes in vitro. The conditional deletion of Rcor2 led to decreased adiposity in fracture callus. Taken together, these results suggest that epigenetic regulation of mesenchymal stromal cell differentiation is mediated by Rcor2, which could thus play an important role in defining the MSC fate.

An Injectable Black Phosphorus Hydrogel for Rapid Tooth Extraction Socket Healing

The excess production of reactive oxygen species (ROS) will delay tooth extraction socket (TES) healing. In this study, we developed an injectable thermosensitive hydrogel (NBP@BP@CS) used to treat TES healing. The hydrogel formulation incorporated black phosphorus (BP) nanoflakes, recognized for their accelerated alveolar bone regeneration and ROS-scavenging properties, and dl-3-n-butylphthalide (NBP), a vasodilator aimed at enhancing angiogenesis. In vivo investigations strongly demonstrated that NBP@BP@CS improved TES healing due to antioxidation and promotion of alveolar bone regeneration by BP nanoflakes. The sustained release of NBP from the hydrogel promoted neovascularization and vascular remodeling. Our results demonstrated that the designed thermosensitive hydrogel provided great opportunity not only for ROS elimination but also for the promotion of osteogenesis and angiogenesis, reflecting the "three birds with one stone" concept, and has tremendous potential for rapid TES healing.

3D-printed near-infrared-light-responsive on-demand drug-delivery scaffold for bone regeneration

Although several bioactive 3D-printed bone scaffolds loaded with multiple kinds of biomolecules for enhanced bone regeneration have been recently developed, the manipulation of on-demand release profiles of different biomolecules during bone regeneration remains challenging. Herein, a 3D-printed dual-drug-loaded biomimetic scaffold to regulate the host stem cell recruitment and osteogenic differentiation in a two-stage process for bone regeneration was successfully fabricated. First, a chemotactic small-molecule drug, namely, simvastatin (SIM) was directly incorporated into the hydroxyapatite/collagen bioink for printing and could be rapidly released during the early stage of bone regeneration. Further, near-infrared (NIR)-light-responsive polydopamine-coated hydroxyapatite nanoparticles were designed to deliver the osteogenic drug, i.e., pargyline (PGL) in a controllable manner. Together, our scaffold displayed an on-demand sequential release of those two drugs and could optimize their therapeutic effects to align with the stem cell recruitment and osteoblastic differentiation, thereby promoting bone regeneration. The results confirmed the suitable mechanical strength, high photothermal conversion efficiency, good biocompatibility of our scaffold. The scaffold loaded with SIM could efficiently accelerate the migration of stem cells. In addition, the scaffold with on-demand sequential release promoted alkaline phosphatase (ALP) activity, significantly upregulated gene expression levels of osteogenesis-related markers, and enhanced new-bone-formation capabilities in rabbit cranial defect models. Altogether, this scaffold not only offers a promising strategy to control the behavior of stem cells during bone regeneration but also provides an efficient strategy for controllable sequential release of different biomolecule in bone tissue engineering.

Effect of LSD1 on osteogenic differentiation of human periodontal ligament stem cells in periodontitis

OBJECTIVE

Periodontitis is a chronic inflammation of periodontal tissues. This study is expected to assess the effect of LSD1 on the osteogenic differentiation of hPDLSCs in periodontitis.

METHODS

hPDLSCs were separated, cultivated, and identified, and then treated by LPS to induce inflammatory microenvironment and subjected to osteogenic differentiation. Subsequently, LSD1 expression was determined, and then silenced to assess its effect on hPDLSCs. Next, the binding relation between LSD1 and miR-590-3p was analyzed. miR-590-3p expression was detected and then overexpressed to evaluate its role in hPDLSCs in periodontitis. Afterward, the relation between LSD1 and OSX was analyzed. H3K4me2 level and OSX transcription were measured, and the role of H3K4me2 was determined. Additionally, the role of OSX in hPDLSCs was verified.

RESULTS

LSD1 was poorly expressed after osteogenic differentiation of hPDLSCs while it was rescued upon LPS induction. The osteogenic differentiation of hPDLSC in periodontitis was strengthened upon LSD1 downregulation. Besides, miR-590-3p targeted LSD1 transcription, and LSD1 inhibited OSX transcription via H3K4me2 demethylation. miR-590-3p overexpression improved osteogenic differentiation of hPDLSCs in periodontitis. But this improvement was annulled by OSX inhibition.

CONCLUSION

miR-590-3p targeted LSD1 transcription and upregulated H3K4me2 methylation to promote OSX transcription, thereby encouraging osteogenic differentiation of hPDLSCs in periodontitis.

Atf7ip Inhibits Osteoblast Differentiation via Negative Regulation of the Sp7 Transcription Factor

Epigenetic modifications are critical for cell differentiation and growth. As a regulator of H3K9 methylation, Setdb1 is implicated in osteoblast proliferation and differentiation. The activity and nucleus localization of Setdb1 are regulated by its binding partner, Atf7ip. However, whether Atf7ip is involved in the regulation of osteoblast differentiation remains largely unclear. In the present study, we found that Atf7ip expression was upregulated during the osteogenesis of primary bone marrow stromal cells and MC3T3-E1 cells, and was induced in PTH-treated cells. The overexpression of Atf7ip impaired osteoblast differentiation in MC3T3-E1 cells regardless of PTH treatment, as measured by the expression of osteoblast differentiation markers, Alp-positive cells, Alp activity, and calcium deposition. Conversely, the depletion of Atf7ip in MC3T3-E1 cells promoted osteoblast differentiation. Compared with the control mice, animals with Atf7ip deletion in the osteoblasts (Oc-Cre;Atf7ip^f/f) showed more bone formation and a significant increase in the bone trabeculae microarchitecture, as reflected by μ-CT and bone histomorphometry. Mechanistically, Atf7ip contributed to the nucleus localization of Setdb1 in MC3T3-E1, but did not affect Setdb1 expression. Atf7ip negatively regulated Sp7 expression, and through specific siRNA, Sp7 knockdown attenuated the enhancing role of Atf7ip deletion in osteoblast differentiation. Through these data, we identified Atf7ip as a novel negative regulator of osteogenesis, possibly via its epigenetic regulation of Sp7 expression, and demonstrated that Atf7ip inhibition is a potential therapeutic measure for enhancing bone formation.

Dual-Targeted Nanodiscs Revealing the Cross-Talk between Osteogenic Differentiation of Mesenchymal Stem Cells and Macrophages

Ongoing research has highlighted the significance of the cross-play of macrophages and mesenchymal stem cells (MSCs). Lysine-specific demethylase 6B (KDM6B) has been shown to control osteogenic differentiation of MSCs by depleting trimethylated histone 3 lysine 27 (H3K27me3). However, to date, the role of KDM6B in bone marrow-derived macrophages (BMDMs) remains controversial. Here, a chromatin immunoprecipitation assay (ChIP) proved that KDM6B derived from osteogenic-induced BMSCs could bind to the promoter region of BMDMs' brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein-1 (BMAL1) gene in a coculture system and activate BMAL1. Transcriptome sequencing and experiments in vitro showed that the overexpression of BMAL1 in BMDM could inhibit the TLR2/NF-κB signaling pathway, reduce pyroptosis, and decrease the M1/M2 ratio, thereby promoting osteogenic differentiation of BMSCs. Furthermore, bone and macrophage dual-targeted GSK-J4 (KDM6B inhibitor)-loaded nanodiscs were synthesized via binding SDSSD-apoA-1 peptide analogs (APA) peptide, which indirectly proved the critical role of KDM6B in osteogenesis in vivo. Overall, we demonstrated that KDM6B serves as a positive circulation trigger during osteogenic differentiation by decreasing the ratio of M1/M2 both in vitro and in vivo. Collectively, these results provide insight into basic research in the field of osteoporosis and bone repair.

Additively manufactured pure zinc porous scaffolds for critical-sized bone defects of rabbit femur

Additive manufacturing has received attention for the fabrication of medical implants that have customized and complicated structures. Biodegradable Zn metals are revolutionary materials for orthopedic implants. In this study, pure Zn porous scaffolds with diamond structures were fabricated using customized laser powder bed fusion (L-PBF) technology. First, the mechanical properties, corrosion behavior, and biocompatibility of the pure Zn porous scaffolds were characterized in vitro. The scaffolds were then implanted into the rabbit femur critical-size bone defect model for 24 weeks. The results showed that the pure Zn porous scaffolds had compressive strength and rigidity comparable to those of cancellous bone, as well as relatively suitable degradation rates for bone regeneration. A benign host response was observed using hematoxylin and eosin (HE) staining of the heart, liver, spleen, lungs, and kidneys. Moreover, the pure Zn porous scaffold showed good biocompatibility and osteogenic promotion ability in vivo. This study showed that pure Zn porous scaffolds with customized structures fabricated using L-PBF represent a promising biodegradable solution for treating large bone defects.

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L-PBF used to fabricate pure Zn porous scaffolds for bone implants.

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Degradation rates and mechanical strength suitable for bone implants.

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Pure Zn porous scaffolds showed good in vitro cytocompatibility with MC3T3-E1 cells.

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Pure Zn porous scaffolds have potential for large bone defect applications with osteogenic ability.

Epigenetics: Novel crucial approach for osteogenesis of mesenchymal stem cells

Bone has a robust regenerative potential, but its capacity to repair critical-sized bone defects is limited. In recent years, stem cells have attracted significant interest for their potential in tissue engineering. Applying mesenchymal stem cells (MSCs) for enhancing bone regeneration is a promising therapeutic strategy. However, maintaining optimal cell efficacy or viability of MSCs is limited by several factors. Epigenetic modification can cause changes in gene expression levels without changing its sequence, mainly including nucleic acids methylation, histone modification, and non-coding RNAs. This modification is believed to be one of the determinants of MSCs fate and differentiation. Understanding the epigenetic modification of MSCs can improve the activity and function of stem cells. This review summarizes recent advances in the epigenetic mechanisms of MSCs differentiation into osteoblast lineages. We expound that epigenetic modification of MSCs can be harnessed to treat bone defects and promote bone regeneration, providing potential therapeutic targets for bone-related diseases.

CircRNA AFF4 induced by KDM1A promotes osteogenic differentiation through FNDC5/Irisin pathway

Background

Circular RNA (circ) AFF4 was documented to regulate osteogenesis but the underlying mechanism remains to be elucidated. The preliminary study showed that circ_AFF4 may promote osteogenesis via FNDC5/Irisin. Furthermore, the online prediction tool indicated the interaction of circ_AFF4, insulin-like growth factor-2 mRNA-binding protein 3 (IGF2BP3), FNDC5 and lysine (K)-specific demethylase 1 A (KDM1A). Therefore, this study aims to elucidate the relationships of KDM1A, circ_AFF4, IGF2BP3 and FNDC5/Irisin during osteogenesis.

Methods

The alkaline phosphatase (ALP) activities and osteogenic-related factors were determined using ALP and alizarin red S (ARS) staining, real-time quantitative PCR(RT-qPCR) and western blot. Immunoprecipitation (RIP), pull-down assay and fluorescence in situ hybridization (FISH) were used to examine the interactions among circ_AFF4/IGF2BP3/FNDC5. A mouse in vivo model was utilized to further confirm the regulatory effect on bone formation.

Results

Circ_AFF4 and KDM1A expression levels were increased during osteoinduction of BM-MSCs. Knockdown of circ_AFF4 and KDM1A significantly suppressed BM-MSC osteogenesis. We also proved that KDM1A directly bound to circ_AFF4 and FNDC5 promoter and induced circ_AFF4 and FNDC5 expression. Furthermore, circ_AFF4 enhanced the stability of FNDC5 by generating a circ_AFF4, IGF2BP3 and FNDC5 RNA-protein complex, and thereby induced Irisin and osteogenesis. The in vitro data was confirmed with in vivo model.

Conclusion

These findings elucidate that KDM1A induces circ_AFF4, which promotes promote osteogenesis via IGF2BP3. This study indicates that circ_AFF4 may potentially represent a critical therapeutic target for the diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00557-7.

pH Stimuli-Responsive, Rapidly Self-healable Coatings Enhanced the Corrosion Resistance and Osteogenic Differentiation of Mg-1Ca Osteoimplant

Mg-Ca alloys have emerged as a promising research direction for biomedical implants in the orthopedic field. However, their clinical use is deterred by their fast corrosion rate. In this work, a pH stimuli-responsive silk-halloysite (HNT)/phytic acid (PA) self-healing coating (Silk-HNT/PA) is constructed to slow down the corrosion rate of Mg-1Ca alloy and its cell viability and osteogenic differentiation ability are enhanced. The Silk-HNT/PA coating exhibits appealing active corrosion protection, by eliciting pH-triggerable self-healing effects, while simultaneously affording superior biocompatibility and osteogenic differentiation ability. Moreover, in vivo studies by histological analysis also demonstrate better osseointegration for the Silk-HNT/PA coated Mg-1Ca alloy. In summary, the Silk-HNT/PA coating in the present study has great potential in enhancing the biomedical utility of Mg alloys.

LSD1 inhibitors for anticancer therapy: a patent review (2017-present)

INTRODUCTION

Lysine-specific demethylase 1 (LSD1), which belongs to the demethylase of non-histone proteins, is believed to promote cancer cell proliferation and metastasis by modifying histones. LSD1 dysfunction may play a key role in a variety of cancers, such as acute myeloid leukemia and non-small cell lung cancer, indicating that LSD1 is a promising epigenetic target for cancer therapy. Many different types of small molecule LSD1 inhibitors have been developed and shown to inhibit tumor cell proliferation, invasion, and migration, providing a new treatment strategy for solid tumors.

AREAS COVERED

This review summarizes the progress of LSD1 inhibitor research in the last four years, including selected new patents and article publications, as well as the therapeutic potential of these compounds.

EXPERT OPINION

Natural products offer a promising prospect for developing novel potent LSD1 inhibitors, as structural design and activity of irreversible and reversible inhibitors have been continuously optimized since the discovery of the LSD1 target in 2004. The use of "microtubule-binding agents" and "dual-agent combination" has recently become a new anticancer technique, reducing the resistance and adverse reactions of traditional drugs. Several microtubule-binding drugs have been used successfully in clinical practice, providing structural scaffolds and new ideas for the development of safer drugs.

LncRNAs and their RBPs: How to influence the fate of stem cells?

Stem cells are distinctive cells that have self-renewal potential and unique ability to differentiate into multiple functional cells. Stem cell is a frontier field of life science research and has always been a hot spot in biomedical research. Recent studies have shown that long non-coding RNAs (lncRNAs) have irreplaceable roles in stem cell self-renewal and differentiation. LncRNAs play crucial roles in stem cells through a variety of regulatory mechanisms, including the recruitment of RNA-binding proteins (RBPs) to affect the stability of their mRNAs or the expression of downstream genes. RBPs interact with different RNAs to regulate gene expression at transcriptional and post-transcriptional levels and play important roles in determining the fate of stem cells. In this review, the functions of lncRNAs and their RBPs in self-renewal and differentiation of stem cell are summarized. We focus on the four regulatory mechanisms by which lncRNAs and their RBPs are involved in epigenetic regulation, signaling pathway regulation, splicing, mRNA stability and subcellular localization and further discuss other noncoding RNAs (ncRNAs) and their RBPs in the fate of stem cells. This work provides a more comprehensive understanding of the roles of lncRNAs in determining the fate of stem cells, and a further understanding of their regulatory mechanisms will provide a theoretical basis for the development of clinical regenerative medicine.

Lysine-Specific Demethylase 1 (LSD1) epigenetically controls osteoblast differentiation

Epigenetic mechanisms regulate osteogenic lineage differentiation of mesenchymal stromal cells. Histone methylation is controlled by multiple lysine demethylases and is an important step in controlling local chromatin structure and gene expression. Here, we show that the lysine-specific histone demethylase Kdm1A/Lsd1 is abundantly expressed in osteoblasts and that its suppression impairs osteoblast differentiation and bone nodule formation in vitro. Although Lsd1 knockdown did not affect global H3K4 methylation levels, genome-wide ChIP-Seq analysis revealed high levels of Lsd1 at gene promoters and its binding was associated with di- and tri-methylation of histone 3 at lysine 4 (H3K4me2 and H3K4me3). Lsd1 binding sites in osteoblastic cells were enriched for the Runx2 consensus motif suggesting a functional link between the two proteins. Importantly, inhibition of Lsd1 activity decreased osteoblast activity in vivo. In support, mesenchymal-targeted knockdown of Lsd1 led to decreased osteoblast activity and disrupted primary spongiosa ossification and reorganization in vivo. Together, our studies demonstrate that Lsd1 occupies Runx2-binding cites at H3K4me2 and H3K4me3 and its activity is required for proper bone formation.

microRNA-491-5p regulates osteogenic differentiation of bone marrow stem cells in type 2 diabetes

OBJECTIVES

Osseointegration of oral implants has a low success rate in patients with type 2 diabetes. This is because of the inhibition of osteogenic differentiation in the jawbone marrow mesenchymal stem cells, in which the expression of microRNA(miR)-491-5p is significantly downregulated, as ascertained through gene chip screening. However, the underlying mechanisms are unclear. Here, we aimed to clarify the mechanisms involved in the influence of miR-491-5p on osteogenic differentiation.

SUBJECTS AND METHODS

Jawbone marrow mesenchymal stem cells were isolated from jawbones of patients with type 2 diabetes and subjected to bioinformatics and functional analyses. Osteogenesis experiments were conducted using the isolated cells and an in vivo model.

RESULTS

Knockdown and overexpression experiments revealed the positive effects of miR-491-5p expression on osteogenic differentiation in vivo and in vitro. Additionally, a dual-luciferase assay revealed that miR-491-5p targeted the SMAD/RUNX2 pathway by inhibiting the expression of epidermal growth factor receptor.

CONCLUSIONS

miR-491-5p is vital in osteogenic differentiation of jawbone mesenchymal stem cells; its downregulation in type 2 diabetes could be a major cause of decreased osteogenic differentiation. Regulation of miR-491-5p expression could improve osteogenic differentiation of jawbone mesenchymal stem cells in patients with type 2 diabetes.

Human amnion-derived mesenchymal stem cells promote osteogenic differentiation of lipopolysaccharide-induced human bone marrow mesenchymal stem cells via ANRIL/miR-125a/APC axis

BACKGROUND AND AIM

Periodontitis is a chronic inflammatory disease inducing the absorption of alveolar bone and leading to tooth loss. Human amnion-derived mesenchymal stem cells (HAMSCs) have been used for studying inflammatory processes. This study aimed to explore the role of long noncoding RNA (lncRNA) antisense noncoding RNA in the INK4 locus (ANRIL) in HAMSC-driven osteogenesis in lipopolysaccharide (LPS)-induced human bone marrow mesenchymal stem cells (HBMSCs).

METHODS

The cells were incubated with a co-culture system. Reactive oxygen species (ROS) level and superoxide dismutase (SOD) activity were used to detect the oxidative stress level. Flow cytometry was performed to determine cell proliferation. The alkaline phosphatase (ALP) activity, Alizarin red assay, cell transfection, and rat mandibular defect model were used to evaluate the osteogenic differentiation. Quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blot analysis, dual-luciferase reporter assay, and immunofluorescence staining were used to evaluate the molecular mechanisms.

RESULTS

This study showed that HAMSCs promoted the osteogenesis of LPS-induced HBMSCs, while the ANRIL level in HBMSCs decreased during co-culture. ANRIL had no significant influence on the proliferation of LPS-induced HBMSCs. However, its overexpression inhibited the HAMSC-driven osteogenesis in vivo and in vitro, whereas its knockdown reversed these effects. Mechanistically, this study found that downregulating ANRIL led to the overexpression of microRNA-125a (miR-125a), and further contributed to the competitive binding of miR-125a and adenomatous polyposis coli (APC), thus significantly activating the Wnt/β-catenin pathway.

CONCLUSION

The study indicated that HAMSCs promoted the osteogenic differentiation of LPS-induced HBMSCs via the ANRIL/miR-125a/APC axis, and offered a novel approach for periodontitis therapy.

miR-140 inhibits osteogenic differentiation of human periodontal ligament fibroblasts through ras homolog gene family, member A -transcriptional co-activator with PDZ-binding motif pathway

Osteogenesis induced by mechanical stretch is the main factor affecting the orthodontic treatment. Due to the masticatory force transmitted by tooth, human periodontal ligament fibroblasts (hPDLFs) could enhance osteogenic differentiation, and remolding of periodontal. Therefore, in-depth study of hPDLFs osteogenic differentiation and its regulatory mechanism is helpful in the understanding of periodontal remolding promoted by orthodontic force. In the present study, 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide showed that miR-140 inhibited the viability of hPDLFs cells. Moreover, we provided evidence that miR-140 inhibited alkaline phosphatase (ALP) activity, Alizarin Red S (ARS) activity and the mRNA expression of osteogenesis associated genes, including ALP, runt-related transcription factor 2, collagen 1, and osteocalcin. Besides, double-luciferase reporter result demonstrated that Ras homolog gene family, member A (RhoA) was a downstream target gene of miR-140, and by inhibiting RhoA-transcriptional co-activator with PDZ-binding motif (TAZ) signaling pathway, miR-140 suppressed the osteogenesis differentiation of hPDLFs. Furthermore, overexpression of RhoA or TAZ promoted ALP activity, ARS activity and osteogenesis associated genes expression, which was inhibited by miR-140 mimics. Our findings not only provided a possible mechanism of hPDLFs osteogenic differentiation but also proposed the clinical application of miR-140 inhibitor to target RhoA-TAZ for orthodontic treatment.

Splicing- and demethylase-independent functions of LSD1 in zebrafish primitive hematopoiesis

LSD1/KDM1A is a widely conserved lysine-specific demethylase that removes methyl groups from methylated proteins, mainly histone H3. We previously isolated the zebrafish LSD1 gene and demonstrated that it is required for primitive hematopoiesis. Recently, a neuron-specific splicing variant of LSD1 was found in mammals and its specific functions and substrate specificities were reported. To our surprise, zebrafish LSD1 cDNA, which we previously analyzed, was corresponded to the neuron-specific variant in mammals. In this study, we investigated the structures and expression of LSD1 splicing variants in zebrafish and found all 4 types of LSD1 isoforms: LSD1, LSD1+2al, LSD1+8al and LSD1+2al8al. Interestingly, LSD1+8al/LSD1+2al8al, which correspond to mammalian neuron-specific variants, expressed ubiquitously in zebrafish. We also performed phenotypic rescue experiments of a zebrafish LSD1 mutant (kdm1a^it627) using human and zebrafish LSD1 variants to identify which variant is involved in primitive hematopoiesis. Unexpectedly, the overexpression of all types of human and zebrafish variants was able to rescue the hematopoietic phenotypes in LSD1 mutants. Furthermore, enzymatic-deficient LSD1K661A (human) and K638A (zebrafish) were also able to rescue the mutant phenotypes. These results suggest that the LSD1 functions in zebrafish primitive hematopoiesis are free from any splicing-dependent regulation or demethylation reaction.

Human amnion-derived mesenchymal stem cells promote osteogenic differentiation of human bone marrow mesenchymal stem cells via H19/miR-675/APC axis

Bone volume inadequacy is an emerging clinical problem impairing the feasibility and longevity of dental implants. Human bone marrow mesenchymal stem cells (HBMSCs) have been widely used in bone remodeling and regeneration. This study examined the effect of long noncoding RNAs (lncRNAs)-H19 on the human amnion-derived mesenchymal stem cells (HAMSCs)-droved osteogenesis in HBMSCs. HAMSCs and HBMSCs were isolated from abandoned amniotic membrane samples and bone marrow. The coculture system was conducted using transwells, and H19 level was measured by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR). The mechanism was further verified. We here discovered that osteogenesis of HBMSCs was induced by HAMSCs, while H19 level in HAMSCs was increased during coculturing. H19 had no significant effect on the proliferative behaviors of HBMSCs, while its overexpression of H19 in HAMSCs led to the upregulated osteogenesis of HBMSCs in vivo and in vitro; whereas its knockdown reversed these effects. Mechanistically, H19 promoted miR-675 expression and contributed to the competitively bounding of miR-675 and Adenomatous polyposis coli (APC), thus significantly activating the Wnt/β-catenin pathway. The results suggested that HAMSCs promote osteogenic differentiation of HBMSCs via H19/miR-675/APC pathway, and supply a potential target for the therapeutic treatment of bone-destructive diseases.

Genetical modification on adipose-derived stem cells facilitates facial nerve regeneration

Adipose-derived stem cells (ASCs) have a demonstrative therapeutic potential in aging-associated facial nerve regeneration, in which ASCs work as a source of Schwann cells therapy as an alternative to autologous nerve grafts. However, the transplantation of ASCs may induce local fibrosis, which causes inferior outcome. Here, we aimed to use genetic modification approaches to reduce the fibrogenic properties of ASCs to improve their therapeutic effects on facial nerve regeneration. Since procollagen-lysine 1, 2-oxoglutarate 5-dioxygenase 1 (PLOD1) is essential for hydroxylation of lysine residues in collagen telopeptides and for collagen pyridinoline cross-link formation during fibrosis, and since we found that ASCs expressed high levels of PLOD1, we depleted PLOD1 in ASCs by expression of either a short-hair interfering RNA for PLOD1 (shPLOD1) or a microRNA-449 (miR-449), the latter of which targets PLOD1 mRNA to suppress protein translation. Transplantation of either ASCs-shPLOD1 or ASCs-miR-449 or ASCs-control to repair a 6mm-gap in rat facial nerve was compared. Either ASCs-shPLOD1 or ASCs-miR-449 exhibited a better facial nerve function. Mechanistically, ASCs-shPLOD1 or ASCs-miR-449 significantly and similarly reduced the fibrosis in the injured region, likely through suppression of reactive oxygen species (ROS) and activation of myofibroblasts.

Homeobox C8 inhibited the osteo-/dentinogenic differentiation and migration ability of stem cells of the apical papilla via activating KDM1A

Enhancing the functions of mesenchymal stem cells (MSCs) is considered a potential approach for promoting tissue regeneration. In the present study, we investigate the role of HOXC8 in regulating differentiation and migration by using stem cells of the apical papilla (SCAPs). Our results showed that overexpression of HOXC8 suppressed the osteo-/dentinogenic differentiation, as detected by measuring alkaline phosphatase activity, in vitro mineralization, and the expressions of dentin sialophosphoprotein, dentin matrix acidic phosphoprotein 1, bone sialoprotein, runt-related transcription factor 2, and osterix in SCAPs, and inhibited in vivo osteo-/dentinogenesis of SCAPs. In addition, knockdown of HOXC8 promoted the osteo-/dentinogenic differentiation potentials of SCAPs. Mechanically, HOXC8 enhanced KDM1A transcription by directly binding to its promoter. HOXC8 and KDM1A also inhibited the migration and chemotaxis abilities of SCAPs. To sum up, HOXC8 negatively regulated the osteo-/dentinogenic differentiation and migration abilities of SCAPs by directly enhancing KDM1A transcription and indicated that HOXC8 and KDM1A could serve as potential targets for enhancing dental MSC mediated tissue regeneration.

A dual role of dLsd1 in oogenesis: regulating developmental genes and repressing transposons

The histone demethylase LSD1 is a key chromatin regulator that is often deregulated in cancer. Its ortholog, dLsd1 plays a crucial role in Drosophila oogenesis; however, our knowledge of dLsd1 function is insufficient to explain its role in the ovary. Here, we have performed genome-wide analysis of dLsd1 binding in the ovary, and we document that dLsd1 is preferentially associated to the transcription start site of developmental genes. We uncovered an unanticipated interplay between dLsd1 and the GATA transcription factor Serpent and we report an unexpected role for Serpent in oogenesis. Besides, our transcriptomic data show that reducing dLsd1 levels results in ectopic transposable elements (TE) expression correlated with changes in H3K4me2 and H3K9me2 at TE loci. In addition, our results suggest that dLsd1 is required for Piwi dependent TE silencing. Hence, we propose that dLsd1 plays crucial roles in establishing specific gene expression programs and in repressing transposons during oogenesis.

LSD1/KDM1A, a Gate-Keeper of Cancer Stemness and a Promising Therapeutic Target

A new exciting area in cancer research is the study of cancer stem cells (CSCs) and the translational implications for putative epigenetic therapies targeted against them. Accumulating evidence of the effects of epigenetic modulating agents has revealed their dramatic consequences on cellular reprogramming and, particularly, reversing cancer stemness characteristics, such as self-renewal and chemoresistance. Lysine specific demethylase 1 (LSD1/KDM1A) plays a well-established role in the normal hematopoietic and neuronal stem cells. Overexpression of LSD1 has been documented in a variety of cancers, where the enzyme is, usually, associated with the more aggressive types of the disease. Interestingly, recent studies have implicated LSD1 in the regulation of the pool of CSCs in different leukemias and solid tumors. However, the precise mechanisms that LSD1 uses to mediate its effects on cancer stemness are largely unknown. Herein, we review the literature on LSD1's role in normal and cancer stem cells, highlighting the analogies of its mode of action in the two biological settings. Given its potential as a pharmacological target, we, also, discuss current advances in the design of novel therapeutic regimes in cancer that incorporate LSD1 inhibitors, as well as their future perspectives.

The role of epigenetic modifications in the osteogenic differentiation of adipose-derived stem cells

Over the last decade, stem cells have drawn extensive attention from scientists due to their full potential in tissue engineering, gene therapy, and cell therapy. Adipose-derived stem cells (ADSCs), which represent one type of mesenchymal stem cell (MSC), hold great promise in bone tissue engineering due to their painless collection procedure, their ability to self-renew and their multi-lineage differentiation properties. Major epigenetic mechanisms, which involve DNA methylation, histone modifications and RNA interference (RNAi), are known to represent one of the determining factors of ADSC fate and differentiation. Understanding the epigenetic modifications of ADSCs may provide a clue for improving stem cell therapy in bone repair and regeneration. The aim of this review is to present the recent advances in understanding the epigenetic mechanisms that facilitate ADSC differentiation into an osteogenic lineage, in addition to the characteristics of the main epigenetic modifications.

Mitochondrial Phosphoenolpyruvate Carboxykinase Regulates Osteogenic Differentiation by Modulating AMPK/ULK1-Dependent Autophagy

Mitochondrial phosphoenolpyruvate carboxykinase (PCK2) is a rate‐limiting enzyme that plays critical roles in multiple physiological processes. The decompensation of PCK2 leads to various energy metabolic disorders. However, little is known regarding the effects of PCK2 on osteogenesis by human mesenchymal stem cells (hMSCs). Here, we report a novel function of PCK2 as a positive regulator of MSCs osteogenic differentiation. In addition to its well‐known role in anabolism, we demonstrate that PCK2 regulates autophagy. PCK2 deficiency significantly suppressed autophagy, leading to the impairment of osteogenic capacity of MSCs. On the other hand, autophagy was promoted by PCK2 overexpression; this was accompanied by increased osteogenic differentiation of MSCs. Moreover, PCK2 regulated osteogenic differentiation of MSCs via AMP‐activated protein kinase (AMPK)/unc‐51 like autophagy activating kinase 1(ULK1)‐dependent autophagy. Collectively, our present study unveiled a novel role for PCK2 in integrating autophagy and bone formation, providing a potential target for stem cell‐based bone tissue engineering that may lead to improved therapies for metabolic bone diseases. stem cells2019;37:1542–1555

Asymmetrical methyltransferase PRMT3 regulates human mesenchymal stem cell osteogenesis via miR-3648

Histone arginine methylation, which is catalyzed by protein arginine methyltransferases (PRMTs), plays a key regulatory role in various biological processes. Several PRMTs are involved in skeletal development; however, their role in the osteogenic differentiation of mesenchymal stem cells (MSCs) is not completely clear. In this study, we aimed to elucidate the function of PRMT3, a type-I PRMT that catalyzes the formation of ω-mono- or asymmetric dimethyl arginine, in MSCs osteogenesis. We found that PRMT3 promoted MSCs osteogenic commitment and bone remodeling. PRMT3 activated the expression of miR-3648 by enhancing histone H4 arginine 3 asymmetric dimethylation (H4R3me2a) levels at promoter region of the gene. Overexpression of miR-3648 rescued impaired osteogenesis in PRMT3-deficient cells. Moreover, administration of Prmt3 shRNA or a chemical inhibitor of PRMT3 (SGC707) caused an osteopenia phenotype in mice. These results indicate that PRMT3 is a potential therapeutic target for the treatment of bone regeneration and osteopenia disorders.

MiR-137 knockdown promotes the osteogenic differentiation of human adipose-derived stem cells via the LSD1/BMP2/SMAD4 signaling network

MicroRNAs are a group of endogenous regulators that participate in several cellular physiological processes. However, the role of miR-137 in the osteogenic differentiation of human adipose-derived stem cells (hASCs) has not been reported. This study verified a general downward trend in miR-137 expression during the osteogenic differentiation of hASCs. MiR-137 knockdown promoted the osteogenesis of hASCs in vitro and in vivo. Mechanistically, inhibition of miR-137 activated the bone morphogenetic protein 2 (BMP2)-mothers against the decapentaplegic homolog 4 (SMAD4) pathway, whereas repressed lysine-specific histone demethylase 1 (LSD1), which was confirmed as a negative regulator of osteogenesis in our previous studies. Furthermore, LSD1 knockdown enhanced the expression of BMP2 and SMAD4, suggesting the coordination of LSD1 in the osteogenic regulation of miR-137. This study indicated that miR-137 negatively regulated the osteogenic differentiation of hASCs via the LSD1/BMP2/SMAD4 signaling network, revealing a new potential therapeutic target of hASC-based bone tissue engineering.

Epigenetic-Based Mechanisms of Osteoblast Suppression in Multiple Myeloma Bone Disease

Multiple myeloma (MM) bone disease is characterized by the development of osteolytic lesions, which cause severe complications affecting the morbidity, mortality, and treatment of myeloma patients. Myeloma tumors seeded within the bone microenvironment promote hyperactivation of osteoclasts and suppression of osteoblast differentiation. Because of this prolonged suppression of bone marrow stromal cells’ (BMSCs) differentiation into functioning osteoblasts, bone lesions in patients persist even in the absence of active disease. Current antiresorptive therapy provides insufficient bone anabolic effects to reliably repair MM lesions. It has become widely accepted that myeloma‐exposed BMSCs have an altered phenotype with pro‐inflammatory, immune‐modulatory, anti‐osteogenic, and pro‐adipogenic properties. In this review, we focus on the role of epigenetic‐based modalities in the establishment and maintenance of myeloma‐induced suppression of osteogenic commitment of BMSCs. We will focus on recent studies demonstrating the involvement of chromatin‐modifying enzymes in transcriptional repression of osteogenic genes in MM‐BMSCs. We will further address the epigenetic plasticity in the differentiation commitment of osteoprogenitor cells and assess the involvement of chromatin modifiers in MSC‐lineage switching from osteogenic to adipogenic in the context of the inflammatory myeloma microenvironment. Lastly, we will discuss the potential of employing small molecule epigenetic inhibitors currently used in the MM research as therapeutics and bone anabolic agents in the prevention or repair of osteolytic lesions in MM. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Down-regulated lncRNA MEG3 promotes osteogenic differentiation of human dental follicle stem cells by epigenetically regulating Wnt pathway

Our previous long noncoding RNA (lncRNA) microarray results showed that lncRNA MEG3 (maternally expressed 3) was significantly downregulated in human dental follicle cells than human periodontal ligament cells. Latest studies show that MEG3 contributes to polycomb repressive complex 2 (PRC2) recruitment to silence gene expression. The enhancer of zeste homolog 2 (EZH2), a crucial catalytic subunit of PRC2, mediates gene silencing and participates in cell lineage determination via methyltransferase activity. In this study, we found that the expression of EZH2 and H3K27me3 (trimethylation on lysine 27 in histone H3) decreased during osteogenesis of human dental follicle stem cells (hDFSCs). Knockdown studies of MEG3 and EZH2 by siRNA showed that MEG3/EZH2 negatively regulated osteogenesis of hDFSCs. We investigated the role of Wnt signaling pathway during the osteogenesis of hDFSCs and its relationship with EZH2. Besides, we studied the key genes of the canonical/noncanonical Wnt signaling pathway which might be related to EZH2. ChIP (chromatin immunoprecipitation) analysis showed that these effects were due to the EZH2 regulation of H3K27me3 level on the Wnt genes promotors. We first demonstrated that the decrease of MEG3 or EZH2 activated the Wnt/β-catenin signaling pathway via epigenetically regulating the H3K27me3 level on the Wnt genes promotors. Our research offers a new target for periodontal tissue engineering and osteogenic tissue regeneration.

Histone demethylase LSD1 regulates bone mass by controlling WNT7B and BMP2 signaling in osteoblasts

Multiple regulatory mechanisms control osteoblast differentiation and function to ensure unperturbed skeletal formation and remodeling. In this study we identify histone lysine-specific demethylase 1(LSD1/KDM1A) as a key epigenetic regulator of osteoblast differentiation. Knockdown of LSD1 promoted osteoblast differentiation of human mesenchymal stem cells (hMSCs) in vitro and mice lacking LSD1 in mesenchymal cells displayed increased bone mass secondary to accelerated osteoblast differentiation. Mechanistic in vitro studies revealed that LSD1 epigenetically regulates the expression of WNT7B and BMP2. LSD1 deficiency resulted in increased BMP2 and WNT7B expression in osteoblasts and enhanced bone formation, while downregulation of WNT7B- and BMP2-related signaling using genetic mouse model or small-molecule inhibitors attenuated bone phenotype in vivo. Furthermore, the LSD1 inhibitor tranylcypromine (TCP) could increase bone mass in mice. These data identify LSD1 as a novel regulator of osteoblast activity and suggest LSD1 inhibition as a potential therapeutic target for treatment of osteoporosis.

KDM1A regulated the osteo/dentinogenic differentiation process of the stem cells of the apical papilla via binding with PLOD2

OBJECTIVES

Dental tissue-derived mesenchymal stem cells (MSCs)-mediated pulp-dentin regeneration is considered a potential approach for the regeneration of damaged teeth. Enhancing MSC-mediated pulp-dentin regeneration is based on an understanding of the molecular mechanisms underlying directed cell differentiation process. Histone demethylation enzyme, lysine demethylase 1A (KDM1A) can regulate the differentiation of some MSCs, but its role in dental tissue-derived MSCs is unclear.

MATERIAL AND METHODS

We obtained SCAPs from immature teeth. Alkaline phosphatase (ALP) activity assay, Alizarin red staining, quantitative calcium analysis, osteogenesis-related genes expression and in vivo transplantation experiment were used to explore the osteo/dentinogenic differentiation. Co-immunoprecipitation (Co-IP) assay was used to investigate the binding protein.

RESULTS

Knock-down of KDM1A reduced ALP activity and mineralization, promoted the expressions of osteo/dentinogenic differentiation markers DSPP, DMP1, BSP and key transcript factors, RUNX2, OSX, DLX2 in SCAPs, and also enhanced the osteo/dentinogenesis in vivo. In addition, KDM1A could associate with PLOD2 to form protein complex. And knock-down of PLOD2 inhibited ALP activity and mineralization, and promoted the expressions of DSPP, DMP1, BSP, RUNX2, OSX and DLX2 in SCAPs.

CONCLUSIONS

KDM1A might have different role in different stages of osteo/dentinogenic differentiation process by binding partner with PLOD2, and finally resulted in the inhibited function for the osteo/dentinogenesis in SCAPs. Our studies provided a further understanding of the regulatory mechanisms of dynamic osteo/dentinogenic differentiation process in dental tissue MSCs.

Adipose tissue stem cells in regenerative medicine

Adipose tissue-derived stem cells (ADSCs) are mesenchymal cells with the capacity for self-renewal and multipotential differentiation. This multipotentiality allows them to become adipocytes, chondrocytes, myocytes, osteoblasts and neurocytes among other cell lineages. Stem cells and, in particular, adipose tissue-derived cells, play a key role in reconstructive or tissue engineering medicine as they have already proven effective in developing new treatments. The purpose of this work is to review the applications of ADSCs in various areas of regenerative medicine, as well as some of the risks associated with treatment with ADSCs in neoplastic disease.

CHD1 regulates cell fate determination by activation of differentiation-induced genes

The coordinated temporal and spatial activation of gene expression is essential for proper stem cell differentiation. The Chromodomain Helicase DNA-binding protein 1 (CHD1) is a chromatin remodeler closely associated with transcription and nucleosome turnover downstream of the transcriptional start site (TSS). In this study, we show that CHD1 is required for the induction of osteoblast-specific gene expression, extracellular-matrix mineralization and ectopic bone formation in vivo. Genome-wide occupancy analyses revealed increased CHD1 occupancy around the TSS of differentiation-activated genes. Furthermore, we observed that CHD1-dependent genes are mainly induced during osteoblast differentiation and are characterized by higher levels of CHD1 occupancy around the TSS. Interestingly, CHD1 depletion resulted in increased pausing of RNA Polymerase II (RNAPII) and decreased H2A.Z occupancy close to the TSS, but not at enhancer regions. These findings reveal a novel role for CHD1 during osteoblast differentiation and provide further insights into the intricacies of epigenetic regulatory mechanisms controlling cell fate determination.

Protein deubiquitinase USP7 is required for osteogenic differentiation of human adipose-derived stem cells

BACKGROUND

Human adipose-derived stem cells (hASCs) are multipotent progenitor cells with self-renewal capabilities and multilineage differentiation potential, including osteogenesis. Although protein deubiquitinases have been linked to stem cell fate determination, whether protein deubiquitination contributes to lineage commitment during osteogenic differentiation of hASCs remains to be investigated. The objective of this study was to evaluate the effects of the ubiquitin specific protease 7 (USP7) on osteogenic differentiation of hASCs.

METHODS

An osteocalcin promoter driven luciferase reporter system was established to initially discover the potential association between USP7 and hASC osteogenesis. To further characterize the function of USP7 in osteogenic differentiation of hASCs, a combination of in vitro and in vivo experiments were carried out through genetic depletion or overexpression of USP7 using a lentiviral strategy. Moreover, HBX 41,108, a cyanoindenopyrazine-derived deubiquitinase inhibitor of USP7, was utilized at different doses to further examine whether USP7 regulated osteogenic differentiation of hASCs through its enzymatic activity.

RESULTS

We demonstrated that USP7 depletion was associated with remarkable downregulation of the reporter gene activity. Genetic depletion of USP7 by lentiviral RNAi markedly suppressed hASC osteogenesis both in vitro and in vivo, while overexpression of USP7 enhanced the osteogenic differentiation of hASCs. Notably, chemical blockade via the small molecular inhibitor HBX 41,108 could efficiently mimic the effects of USP7 genetic depletion in a dose-dependent manner.

CONCLUSIONS

Taken together, our study revealed that protein deubiquitinase USP7 is an essential player in osteogenic differentiation of hASCs through its catalytic activity, and supported the pursuit of USP7 as a potential target for modulation of hASC-based stem cell therapy and bone tissue engineering.

When epigenetics meets bioengineering-A material characteristics and surface topography perspective

The field of tissue engineering and regenerative medicine (TE/RM) involves regeneration of tissues and organs using implantable biomaterials. The term epigenetics refers to changes in gene expression that are not encoded in the DNA sequence, leading to remodeling of the chromatin and activation or inactivation of gene expression. Recently, studies have demonstrated that these modifications are influenced not only by biological cues but also by mechanical and topographical signals. This review highlights the current knowledge on emerging approaches in TE/RM with a focus on the effect of materials and topography on the epigenetic expression pattern in cells with potential impacts on modulating regenerative biology. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2065-2071, 2018.

The Circular RNA Landscape of Periodontal Ligament Stem Cells During Osteogenesis

BACKGROUND

The present study aims to investigate the distinct expression pattern of circular RNAs (circRNAs) in periodontal ligament stem cells (PDLSCs) during osteogenesis.

METHODS

PDLSCs were isolated and cultured in osteogenic medium. Total RNA was extracted from cells at day 0 (D0), day 3 (D3), day 7 (D7), and day 14 (D14) and submitted to RNA-sequencing to detect expression profiles of circRNAs, messenger RNAs (mRNAs), and microRNAs (miRNAs). Real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was performed to validate expression of circRNAs and miRNAs. Differential expression analysis and gene ontology analysis were performed. A circRNA-miRNA-mRNA network was constructed to reveal the potential regulatory role of circRNAs.

RESULTS

A total of 12,693 circRNA transcripts were detected, and circRNAs displayed stage-specific expression. Expression of four well-known circRNAs was validated by qRT-PCR. In total, 118 circRNAs were differentially expressed at D3, 128 circRNAs were differentially expressed at D7, and 139 circRNAs were differentially expressed at D14 compared with D0. Host genes of differentially expressed circRNAs were enriched in cytoplasmic or membrane-bound vesicles and extracellular matrix, indicating their potential roles in modulating biogenesis of extracellular vesicles. Moreover, mRNAs that were potentially regulated by circRNAs were enriched in bone-formation-associated processes, including extracellular matrix organization, cell differentiation, and bone morphogenetic protein signaling pathway.

CONCLUSION

Expression profiles of circRNAs were significantly altered during osteogenic differentiation of PDLSCs, providing a clue for future studies on the role of circRNAs in osteoblast differentiation.

Ionic Colloidal Molding as a Biomimetic Scaffolding Strategy for Uniform Bone Tissue Regeneration

Inspired by the highly ordered nanostructure of bone, nanodopant composite biomaterials are gaining special attention for their ability to guide bone tissue regeneration through structural and biological cues. However, bone malformation in orthopedic surgery is a lingering issue, partly due to the high surface energy of traditional nanoparticles contributing to aggregation and inhomogeneity. Recently, carboxyl-functionalized synthetic polymers have been shown to mimic the carboxyl-rich surface motifs of non-collagenous proteins in stabilizing hydroxyapatite and directing intrafibrillar mineralization in-vitro. Based on this biomimetic approach, it is herein demonstrated that carboxyl functionalization of poly(lactic-co-glycolic acid) can achieve great material homogeneity in nanocomposites. This ionic colloidal molding method stabilizes hydroxyapatite precursors to confer even nanodopant packing, improving therapeutic outcomes in bone repair by remarkably improving mechanical properties of nanocomposites and optimizing controlled drug release, resulting in better cell in-growth and osteogenic differentiation. Lastly, better controlled biomaterial degradation significantly improved osteointegration, translating to highly regular bone formation with minimal fibrous tissue and increased bone density in rabbit radial defect models. Ionic colloidal molding is a simple yet effective approach of achieving materials homogeneity and modulating crystal nucleation, serving as an excellent biomimetic scaffolding strategy to rebuild natural bone integrity.

Long non-coding RNA MEG3 inhibits adipogenesis and promotes osteogenesis of human adipose-derived mesenchymal stem cells via miR-140-5p

lncRNAs are an emerging class of regulators involved in multiple biological processes. MEG3, an lncRNA, acts as a tumor suppressor, has been reported to be linked with osteogenic differentiation of MSCs. However, limited knowledge is available concerning the roles of MEG3 in the multilineage differentiation of hASCs. The current study demonstrated that MEG3 was downregulated during adipogenesis and upregulated during osteogenesis of hASCs. Further functional analysis showed that knockdown of MEG3 promoted adipogenic differentiation, whereas inhibited osteogenic differentiation of hASCs. Mechanically, MEG3 may execute its role via regulating miR-140-5p. Moreover, miR-140-5p was upregulated during adipogenesis and downregulated during osteogenesis in hASCs, which was negatively correlated with MEG3. In conclusion, MEG3 participated in the balance of adipogenic and osteogenic differentiation of hASCs, and the mechanism may be through regulating miR-140-5p.

Enhancement of individual differences in proliferation and differentiation potentials of aged human adipose-derived stem cells

Background

Adipose-derived stem cells (ASCs) are a robust, multipotent cell source. They are easily obtained and hold promise in many regenerative applications. It is generally considered that the function of somatic stem cells declines with age. Although several studies have examined the effects of donor age on proliferation potential and pluripotency of ASCs, the results of these studies were not consistent.

Objective

This study tested whether the donor age affects the yield of ASCs from adipose tissue, as well as the proliferation and differentiation potentials of ASCs.

Methods

This study used ASCs obtained from adipose tissues of 260 donors (ages 5–97 years). ASCs were examined for individual differences in proliferation, and adipogenic, osteogenic and chondrogenic differentiation potentials in vitro. Characteristics of ASCs from each donor were evaluated by the principal component analysis (PCA) using their potential parameters.

Results

Analyses on ASCs demonstrated that adipogenic potentials declined with age, but proliferation, osteogenic and chondrogenic potentials were not correlated with age. Interestingly, in all ASC potentials, including adipogenesis, individual differences were observed. Principal component analysis (PCA) revealed that individual differences became evident in the elderly, and those variations were more prominent in females than in males.

Conclusions

This study demonstrated age-related changes in the potentials of ASCs and revealed that the individual differences of ASCs become significant in people over 60 years of age (for females over 60, and for males over 80). We believe that it is important to carefully observe ASC potentials in order to achieve effective regenerative medicine treatments using ASCs.

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ASCs can be isolated from subjects in all ages.

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Adipogenic potential of ASCs declines with age.

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Chondrogenic and osteogenic potentials of ASCs are not affected by age.

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Proliferation and differentiation potentials of ASCs are individually different.

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Individual difference of ASC potentials becomes significant over 60 years of age.

Histone demethylase UTX counteracts glucocorticoid deregulation of osteogenesis by modulating histone-dependent and -independent pathways

Excess glucocorticoid administration impairs osteogenic activities, which raises the risk of osteoporotic disorders. Epigenetic methylation of DNA and histone regulates the lineage commitment of progenitor cells. This study was undertaken to delineate the actions of histone lysine demethylase 6a (UTX) with regard to the glucocorticoid impediment of osteogenic differentiation. Osteogenic progenitor cells responded to supraphysiological glucocorticoid by elevating CpG dinucleotide methylation proximal to transcription start sites within Runx2 and osterix promoters and Wnt inhibitor Dickkopf-1 (Dkk1) expression concomitant with low UTX expression. 5'-Aza-deoxycystidine demethylation of Runx2 and osterix promoters abolished the glucocorticoid inhibition of mineralized matrix accumulation. Gain of UTX function attenuated the glucocorticoid-induced loss of osteogenic differentiation, whereas UTX silencing escalated adipogenic gene expression and adipocyte formation. UTX sustained osteogenic gene transcription through maintaining its occupancy to Runx2 and osterix promoters. It also mitigated the trimethylation of histone 3 at lysine 27 (H3K27me3), which reduced H3K27me3 enrichment to Dkk1 promoter and thereby lowered Dkk1 transcription. Modulation of β-catenin and Dkk1 actions restored UTX signaling in glucocorticoid-stressed cells. In vivo, UTX inhibition by exogenous methylprednisolone and GSK-J4 administration, an effect that disturbed H3K27me3, β-catenin, Dkk1, Runx2, and osterix levels, exacerbated trabecular microarchitecture loss and marrow adiposity. Taken together, glucocorticoid reduction of UTX function hindered osteogenic differentiation. Epigenetic hypomethylation of osteogenic transcription factor promoters and H3K27 contributed to the UXT alleviation of Dkk1 transcription and osteogenesis in glucocorticoid-stressed osteogenic progenitor cells. Control of UTX action has an epigenetic perspective of curtailing glucocorticoid impairment of osteogenic differentiation and bone mass.

KEY MESSAGES

UTX attenuates glucocorticoid deregulation of osteogenesis and adipogenesis. UTX reduces Runx2 promoter methylation and H3K27me3 enrichment in the Dkk1 promoter. β-catenin and Dkk1 modulate the glucocorticoid inhibition of UTX signaling. UTX inhibition exacerbates bone mass, trabecular microstructure and fatty marrow. UTX signaling is indispensable in fending off glucocorticoid-impaired osteogenesis.

Lysine-specific demethylase 1 inhibitor rescues the osteogenic ability of mesenchymal stem cells under osteoporotic conditions by modulating H3K4 methylation

Bone tissue engineering may be hindered by underlying osteoporosis because of a decreased osteogenic ability of autologous seed cells and an unfavorably changed microenvironment in these patients. Epigenetic regulation plays an important role in the developmental origins of osteoporosis; however, few studies have investigated the potential of epigenetic therapy to improve or rescue the osteogenic ability of bone marrow mesenchymal stem cells (BMMSCs) under osteoporotic conditions. Here, we investigated pargyline, an inhibitor of lysine-specific demethylase 1 (LSD1), which mainly catalyzes the demethylation of the di- and mono-methylation of H3K4. We demonstrated that 1.5 mmol·L⁻¹ pargyline was the optimal concentration for the osteogenic differentiation of human BMMSCs. Pargyline rescued the osteogenic differentiation ability of mouse BMMSCs under osteoporotic conditions by enhancing the dimethylation level of H3K4 at the promoter regions of osteogenesis-related genes. Moreover, pargyline partially rescued or prevented the osteoporotic conditions in aged or ovariectomized mouse models, respectively. By introducing the concept of epigenetic therapy into the field of osteoporosis, this study demonstrated that LSD1 inhibitors could improve the clinical practice of MSC-based bone tissue engineering and proposes their novel use to treat osteoporosis.

Novel KDM1A inhibitors induce differentiation and apoptosis of glioma stem cells via unfolded protein response pathway

Glioma stem cells (GSCs) have a central role in glioblastoma (GBM) development and chemo/radiation resistance, and their elimination is critical for the development of efficient therapeutic strategies. Recently, we showed that lysine demethylase KDM1A is overexpressed in GBM. In the present study, we determined whether KDM1A modulates GSCs stemness and differentiation and tested the utility of two novel KDM1A-specific inhibitors (NCL-1 and NCD-38) to promote differentiation and apoptosis of GSCs. The efficacy of KDM1A targeting drugs was tested on purified GSCs isolated from established and patient-derived GBMs using both in vitro assays and in vivo orthotopic preclinical models. Our results suggested that KDM1A is highly expressed in GSCs and knockdown of KDM1A using shRNA-reduced GSCs stemness and induced the differentiation. Pharmacological inhibition of KDM1A using NCL-1 and NCD-38 significantly reduced the cell viability, neurosphere formation and induced apoptosis of GSCs with little effect on differentiated cells. In preclinical studies using orthotopic models, NCL-1 and NCD-38 significantly reduced GSCs-driven tumor progression and improved mice survival. RNA-sequencing analysis showed that KDM1A inhibitors modulate several pathways related to stemness, differentiation and apoptosis. Mechanistic studies showed that KDM1A inhibitors induce activation of the unfolded protein response (UPR) pathway. These results strongly suggest that selective targeting of KDM1A using NCL-1 and NCD-38 is a promising therapeutic strategy for elimination of GSCs.

Regulation of Cell Signaling Factors Using PLGA Nanoparticles Coated/Loaded with Genes and Proteins for Osteogenesis of Human Mesenchymal Stem Cells

Transfection of specific genes and transportation of proteins into cells have been a focus of stem cell differentiation research. However, it is not easy to regulate codelivery of a gene and a protein into cells. For codelivery into undifferentiated cells (human mesenchymal stem cells (hMSCs)), we used biodegradable carriers loaded with Runt-related transcription factor 2 (RUNX2) protein and coated with bone morphogenetic protein 2 (BMP2) plasmid DNA (pDNA) to induce osteogenesis. The released gene and protein were first localized in the cytosol of transfected hMSCs, and the gene then moved into the nucleus. The levels of internalized PLGA nanoparticles were tested using different doses and incubation durations. Then, transfection of BMP2 pDNA was confirmed by determining mRNA and protein levels and acquiring cell images. The same techniques were used to assess osteogenesis of hMSCs both in vitro and in vivo upon internalization of PLGA NPs carrying the BMP2 gene and RUNX2 protein. Detection of specific genes and proteins demonstrated that cells transfected with PLGA NPs carrying both the BMP2 gene and RUNX2 protein were highly differentiated compared with other samples. Histological and immunofluorescence analyses demonstrated that transfection of PLGA nanoparticles carrying both the BMP2 gene and RUNX2 protein dramatically enhanced osteogenesis of hMSCs.

MiR-34a Promotes Osteogenic Differentiation of Human Adipose-Derived Stem Cells via the RBP2/NOTCH1/CYCLIN D1 Coregulatory Network

MiR-34a was demonstrated to be upregulated during the osteogenic differentiation of human adipose-derived stem cells (hASCs). Overexpression of miR-34a significantly increased alkaline phosphatase activity, mineralization capacity, and the expression of osteogenesis-associated genes in hASCs in vitro. Enhanced heterotopic bone formation in vivo was also observed upon overexpression of miR-34a in hASCs. Mechanistic investigations revealed that miR-34a inhibited the expression of retinoblastoma binding protein 2 (RBP2) and reduced the luciferase activity of reporter gene construct comprising putative miR-34a binding sites in the 3′ UTR of RBP2. Moreover, miR-34a downregulated the expression of NOTCH1 and CYCLIN D1 and upregulated the expression of RUNX2 by targeting RBP2, NOTCH1, and CYCLIN D1. Taken together, our results suggested that miR-34a promotes the osteogenic differentiation of hASCs via the RBP2/NOTCH1/CYCLIN D1 coregulatory network, indicating that miR-34a-targeted therapy could be a valuable approach to promote bone regeneration.

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MiR-34a promotes osteogenesis of hASCs in vitro and in vivo

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MiR-34a directly binds to the 3′ UTR of RBP2 mRNA in hASCs

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MiR-34a promotes osteogenesis of hASCs via the RBP2/NOTCH1/CYCLIN D1 network

Inhibition of lncRNA MIR31HG Promotes Osteogenic Differentiation of Human Adipose-Derived Stem Cells

Osteogenic differentiation and bone formation is suppressed under condition of inflammation induced by proinflammation cytokines. A number of studies indicate miRNAs play a significant role in tumor necrosis factor-α-induced inhibition of bone formation, but whether long non-coding RNAs are also involved in this process remains unknown. In this study, we evaluated the role of MIR31HG in osteogenesis of human adipose-derived stem cells (hASCs) in vitro and in vivo. The results suggested that knockdown of MIR31HG not only significantly promoted osteogenic differentiation, but also dramatically overcame the inflammation-induced inhibition of osteogenesis in hASCs. Mechanistically, we found MIR31HG regulated bone formation and inflammation via interacting with NF-κB. The p65 subunit bound to the MIR31HG promoter and promoted MIR31HG expression. In turn, MIR31HG directly interacted with IκBα and participated in NF-κB activation, which builds a regulatory circuitry with NF-κB. Targeting this MIR31HG-NF-κB regulatory loop may be helpful to improve the osteogenic capacity of hASCs under inflammatory microenvironment in bone tissue engineering. Stem Cells 2016;34:2707-2720.