Shiwu Dong

Effect of microRNA‐145 on IL‐1β‐induced cartilage degradation in human chondrocytes

MicroRNA‐145 has been shown to regulate chondrocyte homeostasis. It seems that miR‐145 is implicated in cartilage dysfunction in Osteoarthritis (OA). However, the functional role of miR‐145 in interleukin‐1 beta (IL‐1β)‐induced extracellular matrix (ECM) degradation of OA cartilage has never been clarified. Here, we show that miR‐145 expression increased in OA chondrocytes and in response to IL‐1β stimulation. We confirm that mothers against decapentaplegic homolog 3 (Smad3), a key factor in maintaining chondrocyte homeostasis, is directly regulated by miR‐145. Modulation of miR‐145 affects the expression of Smad3 causing a change of its downstream target gene expression as well as IL‐1β‐induced ECM degradation in OA chondrocytes. This indicates that miR‐145 contributes to impaired ECM in OA cartilage probably in part via targeting Smad3.

The effect of mechanical stimulation on the maturation of TDSCs-poly(L-lactide-co-e-caprolactone)/collagen scaffold constructs for tendon tissue engineering

Mechanical stimulation plays an important role in the development and remodeling of tendons. Tendon-derived stem cells (TDSCs) are an attractive cell source for tendon injury and tendon tissue engineering. However, these cells have not yet been fully explored for tendon tissue engineering application, and there is also lack of understanding to the effect of mechanical stimulation on the maturation of TDSCs-scaffold construct for tendon tissue engineering. In this study, we assessed the efficacy of TDSCs in a poly(L-lactide-co-ε-caprolactone)/collagen (P(LLA-CL)/Col) scaffold under mechanical stimulation for tendon tissue engineering both in vitro and in vivo, and evaluated the utility of the transplanted TDSCs-scaffold construct to promote rabbit patellar tendon defect regeneration. TDSCs displayed good proliferation and positive expressed tendon-related extracellular matrix (ECM) genes and proteins under mechanical stimulation in vitro. After implanting into the nude mice, the fluorescence imaging indicated that TDSCs had long-term survival, and the macroscopic evaluation, histology and immunohistochemistry examinations showed high-quality neo-tendon formation under mechanical stimulation in vivo. Furthermore, the histology, immunohistochemistry, collagen content assay and biomechanical testing data indicated that dynamically cultured TDSCs-scaffold construct could significantly contributed to tendon regeneration in a rabbit patellar tendon window defect model. TDSCs have significant potential to be used as seeded cells in the development of tissue-engineered tendons, which can be successfully fabricated through seeding of TDSCs in a P(LLA-CL)/Col scaffold followed by mechanical stimulation.

MiR-7b directly targets DC-STAMP causing suppression of NFATc1 and c-Fos signaling during osteoclast fusion and differentiation

DC-STAMP is a key regulating molecule of osteoclastogenesis and osteoclast precursor (OCP) fusion. Emerging lines of evidence showed that microRNAs play crucial roles in bone metabolism and osteoclast differentiation, but no microRNA has yet been reported to be directly related to OCPs fusion. Through a microarray, we found that the expression of miR-7b in RAW264.7 cells was significantly decreased after induction with M-CSF and RANKL. The overexpression of miR-7b in RAW264.7 cells attenuated the number of TRAP-positive cells number and the formation of multinucleated cells, whereas the inhibition of miR-7b enhanced osteoclastogenesis. Through a dual luciferase reporter assay, we confirmed that miR-7b directly targets DC-STAMP. Other fusogenic molecules, such as CD47, ATP6v0d2, and OC-STAMP, were detected to be down-regulated in accordance with the inhibition of DC-STAMP. Because DC-STAMP also participates in osteoclast differentiation through the ITAM-ITIM network, multiple osteoclast-specific genes in the ITAM-ITIM network were detected to identify how DC-STAMP is involved in this process. The results showed that molecules associated with the ITAM-ITIM network, such as NFATc1 and OSCAR, which are crucial in osteoclastogenesis, were consistently altered due to DC-STAMP inhibition. These findings suggest that miR-7b inhibits osteoclastogenesis and cell-cell fusion by directly targeting DC-STAMP. In addition, the inhibition of DC-STAMP and its downstream signals changed the expression of other fusogenic genes and key regulating genes, such as Nfatc1, c-fos, Akt, Irf8, Mapk1, and Traf6. In conclusion, our findings indicate that miR-7b may be a potential therapeutic target for the treatment of osteoclast-related bone disorders.

Changing expression profiles of lncRNAs, mRNAs, circRNAs and miRNAs during osteoclastogenesis

Bone is a dynamic organ continuously undergoing shaping, repairing and remodeling. The homeostasis of bone is maintained by the balance between osteoblastic bone formation and osteoclastic bone resorption. Osteoclasts (OCs) are specialized multinucleated cells derived from hematopoietic stem cells (HSCs) or monocytes/macrophage progenitor cells. There are different stages during osteoclastogenesis, and one of the most important steps to form functional osteoclasts is realized by cell-cell fusion. In our study, microarray was performed to detect the expression profiles of lncRNA, mRNA, circRNA and miRNA at different stages during osteoclastogenesis of RAW264.7 cells. Often changed RNAs were selected and clustered among the four groups with Venn analysis. The results revealed that expressions of 518 lncRNAs, 207 mRNAs, 24 circRNAs and 37 miRNAs were often altered at each stage during OC differentiation. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) biological pathway analysis were performed to predict the functions of differentially expressed lncRNAs and co-expressed potential targeting genes. Co-expression networks of lncRNA-mRNA and circRNA-miRNA were constructed based on the correlation analysis between the differentially expressed RNAs. The present study provided a systematic perspective on the potential function of non-coding RNAs (ncRNAs) during osteoclastogenesis.

DC-STAMP, the key fusion-mediating molecule in osteoclastogenesis.

As a member of the mononuclear phagocyte system, osteoclasts (OC) absorb the bone matrix and participate in bone modeling by keeping a balance with osteoblasts (OB) and stromal cells. Mature OC derive from the fusion of mononuclear osteoclasts (mOC) and the fusion is considered as the indispensable process for the osteoclastogenesis and absorbing activity of OC. DC‐STAMP (dendritic cell‐specific transmembrane protein) has been validated playing a key role in the fusion of mOC. DC‐STAMP is mainly expressed in OC, macrophages and dendritic cells (DC). While DC‐STAMP was discovered in DC, more attentions have been paid to DC‐STAMP in OC in this decade. This review will mainly focus on the function of DC‐STAMP in OC. Studies on DC‐STAMP in DC may also provide new sight for the study of DC‐STAMP in OC. Since the function of DC‐STAMP is still poorly understood and few studies have been implemented for illustration, many issues are still unknown and need to be revealed. We will also discuss these questions in this review. J. Cell. Physiol. 229: 1330–1335, 2014.

Wnt/beta-catenin is involved in the proliferation of hippocampal neural stem cells induced by hypoxia.

Background and aimBeta-catenin, as a major effector molecule in the canonical Wnt signaling pathway, could regulate adult neurogenesis. Here, the role of Wnt/β-catenin signaling pathway in the proliferation of hippocampal neural stem cells (NSCs) induced by hypoxia was investigated.MethodsThe hippocampal NSCs of neonatal green fluorescent protein transgenic mice on day 0 were cultured in hypoxia (5% O2) and traditional O2 (20% O2). The expression of β-catenin, p-GSK-3β, and cyclinD1 in NSCs was measured under hypoxia or traditional O2 by western blotting. NSCs were electroporated with pTOPFLASH reporter in different conditions and the LEF/TCF-dependent luciferase activity was assayed.ResultsHypoxia increased the proliferation and reduced the apoptosis of hippocampal NSCs. NSCs proliferation was inhibited by transfecting with pAxin, whereas promoted by transfecting with pβ-catenin.ConclusionHypoxia could enhance the proliferation of hippocampal NSCs and β-catenin contributed to this action.

Scaffolding biomaterials for cartilage regeneration

Completely repairing of damaged cartilage is a difficult procedure. In recent years, the use of tissue engineering approach in which scaffolds play a vital role to regenerate cartilage has become a new research field. Investigating the advances in biological cartilage scaffolds has been regarded as the main research direction and has great significance for the construction of artificial cartilage. Native biological materials and synthetic polymeric materials have their advantages and disadvantages. The disadvantages can be overcome through either physical modification or biochemical modification. Additionally, developing composite materials, biomimetic materials, and nanomaterials can make scaffolds acquire better biocompatibility and mechanical adaptability.

A composite demineralized bone matrix--self assembling peptide scaffold for enhancing cell and growth factor activity in bone marrow.

The need for suitable bone grafts is high; however, there are limitations to all current graft sources, such as limited availability, the invasive harvest procedure, insufficient osteoinductive properties, poor biocompatibility, ethical problems, and degradation properties. The lack of osteoinductive properties is a common problem. As an allogenic bone graft, demineralized bone matrix (DBM) can overcome issues such as limited sources and comorbidities caused by invasive harvest; however, DBM is not sufficiently osteoinductive. Bone marrow has been known to magnify osteoinductive components for bone reconstruction because it contains osteogenic cells and factors. Mesenchymal stem cells (MSCs) derived from bone marrow are the gold standard for cell seeding in tissue-engineered biomaterials for bone repair, and these cells have demonstrated beneficial effects. However, the associated high cost and the complicated procedures limit the use of tissue-engineered bone constructs. To easily enrich more osteogenic cells and factors to DBM by selective cell retention technology, DBM is modified by a nanoscale self-assembling peptide (SAP) to form a composite DBM/SAP scaffold. By decreasing the pore size and increasing the charge interaction, DBM/SAP scaffolds possess a much higher enriching yield for osteogenic cells and factors compared with DBM alone scaffolds. At the same time, SAP can build a cellular microenvironment for cell adhesion, proliferation, and differentiation that promotes bone reconstruction. As a result, a suitable bone graft fabricated by DBM/SAP scaffolds and bone marrow represents a new strategy and product for bone transplantation in the clinic.

The Signaling Pathways Involved in Chondrocyte Differentiation and Hypertrophic Differentiation

Chondrocytes communicate with each other mainly via diffusible signals rather than direct cell-to-cell contact. The chondrogenic differentiation of mesenchymal stem cells (MSCs) is well regulated by the interactions of varieties of growth factors, cytokines, and signaling molecules. A number of critical signaling molecules have been identified to regulate the differentiation of chondrocyte from mesenchymal progenitor cells to their terminal maturation of hypertrophic chondrocytes, including bone morphogenetic proteins (BMPs), SRY-related high-mobility group-box gene 9 (Sox9), parathyroid hormone-related peptide (PTHrP), Indian hedgehog (Ihh), fibroblast growth factor receptor 3 (FGFR3), and β-catenin. Except for these molecules, other factors such as adenosine, O2 tension, and reactive oxygen species (ROS) also have a vital role in cartilage formation and chondrocyte maturation. Here, we outlined the complex transcriptional network and the function of key factors in this network that determine and regulate the genetic program of chondrogenesis and chondrocyte differentiation.

Dual Effect of Cyanidin on RANKL-Induced Differentiation and Fusion of Osteoclasts.

Bone homeostasis is maintained by the balance between osteoblastic bone formation and osteoclastic bone resorption. Osteoclasts are multinucleated cells derived from hematopoietic stem cells (HSCs) or monocyte/macrophage progenitor cells and formed by osteoclasts precursors (OCPs) fusion. Cyanidin is an anthocyanin widely distributed in food diet with novel antioxidant activity. However, the effect of cyanidin on osteoclasts is still unknown. We investigated the effect of cyanidin on RANKL‐induced osteoclasts differentiation and cell fusion. The results showed that cyanidin had a dual effect on RANKL‐induced osteoclastogenesis. Lower dosage of cyanidin (< 1µg/ml) has a promoting effect on osteoclastogenesis while higher dosage of cyanidin (> 10µg/ml) has an inhibitory effect. Fusogenic genes like CD9, ATP6v0d2, DC‐STAMP, OC‐STAMP, and osteoclasts related genes like NFATc1, mitf, and c‐fos were all regulated by cyanidin consistent to its dual effect. Further exploration showed that low concentration of cyanidin could increase osteoclasts fusion whereas higher dosage of cyanidin lead to the increase of LXR‐β expression and activation which is suppressive to osteoclasts differentiaton. All these results showed that cyanidin exhibits therapeutic potential in prevention of osteoclasts related bone disorders. J. Cell. Physiol. 231: 558–567, 2016.