TGF-β regulates β-catenin signaling and osteoblast differentiation in human mesenchymal stem cells

Role of LRP5/6/GSK-3β/β-catenin in the differences in exenatide- and insulin-promoted T2D osteogenesis and osteomodulation

BACKGROUND AND PURPOSE

Insulin and exenatide are two hypoglycaemic agents that exhibit different osteogenic effects. This study compared the differences between exenatide and insulin in osseointegration in a rat model of Type 2 diabetes (T2D) and explored the mechanisms promoting osteogenesis in this model of T2D.

EXPERIMENTAL APPROACH

In vivo, micro-CT was used to detect differences in the peri-implant bone microstructure in vivo. Histology, dual-fluorescent labelling, immunofluorescence and immunohistochemistry were used to detect differences in tissue, cell and protein expression around the implants. In vitro, RT-PCR and western blotting were used to measure the expression of osteogenesis- and Wnt signalling-related genes and proteins in bone marrow mesenchymal stromal cells (BMSCs) from rats with T2D (TBMSCs) after PBS, insulin and exenatide treatment. RT-PCR was used to detect the expression of Wnt bypass cascade reactions under Wnt inactivation.

KEY RESULTS

Micro-CT and section staining showed exenatide extensively promoted peri-implant osseointegration. Both in vivo and in vitro experiments showed exenatide substantially increased the expression of osteogenesis-related and activated the LRP5/6/GSK-3β/β-catenin-related Wnt pathway. Furthermore, exenatide suppressed expression of Bmpr1a to inhibit lipogenesis and promoted expression of Btrc to suppress inflammation.

CONCLUSION AND IMPLICATIONS

Compared to insulin, exenatide significantly improved osteogenesis in T2D rats and TBMSCs. In addition to its dependence on LRP5/6/GSK-3β/β-catenin signalling for osteogenic differentiation, exenatide-mediated osteomodulation also involves inhibition of inflammation and adipogenesis by BMPR1A and β-TrCP, respectively.

Xenopus tropicalis osteoblast-specific open chromatin regions reveal promoters and enhancers involved in human skeletal phenotypes and shed light on early vertebrate evolution

While understanding the genetic underpinnings of osteogenesis has far-reaching implications for skeletal diseases and evolution, a comprehensive characterization of the osteoblastic regulatory landscape in non-mammalian vertebrates is still lacking. Here, we compared the ATAC-Seq profile of Xenopus tropicalis (Xt) osteoblasts to a variety of non mineralizing control tissues, and identified osteoblast-specific nucleosome free regions (NFRs) at 527 promoters and 6747 distal regions. Sequence analyses, Gene Ontology, RNA-Seq and ChIP-Seq against four key histone marks confirmed that the distal regions correspond to bona fide osteogenic transcriptional enhancers exhibiting a shared regulatory logic with mammals. We report 425 regulatory regions conserved with human and globally associated to skeletogenic genes. Of these, 35 regions have been shown to impact human skeletal phenotypes by GWAS, including one trps1 enhancer and the runx2 promoter, two genes which are respectively involved in trichorhinophalangeal syndrome type I and cleidocranial dysplasia. Intriguingly, 60 osteoblastic NFRs also align to the genome of the elephant shark, a species lacking osteoblasts and bone tissue. To tackle this paradox, we chose to focus on dlx5 because its conserved promoter, known to integrate regulatory inputs during mammalian osteogenesis, harbours an osteoblast-specific NFR in both frog and human. Hence, we show that dlx5 is expressed in Xt and elephant shark odontoblasts, supporting a common cellular and genetic origin of bone and dentine. Taken together, our work (i) unravels the Xt osteogenic regulatory landscape, (ii) illustrates how cross-species comparisons harvest data relevant to human biology and (iii) reveals that a set of genes including bnc2, dlx5, ebf3, mir199a, nfia, runx2 and zfhx4 drove the development of a primitive form of mineralized skeletal tissue deep in the vertebrate lineage.

Exercise and osteoimmunology in bone remodeling

Bones can form the scaffolding of the body, support the organism, coordinate somatic movements, and control mineral homeostasis and hematopoiesis. The immune system plays immune supervisory, defensive, and regulatory roles in the organism, which mainly consists of immune organs (spleen, bone marrow, tonsils, lymph nodes, etc.), immune cells (granulocytes, platelets, lymphocytes, etc.), and immune molecules (immune factors, interferons, interleukins, tumor necrosis factors, etc.). Bone and the immune system have long been considered two distinct fields of study, and the bone marrow, as a shared microenvironment between the bone and the immune system, closely links the two. Osteoimmunology organically combines bone and the immune system, elucidates the role of the immune system in bone, and creatively emphasizes its interdisciplinary characteristics and the function of immune cells and factors in maintaining bone homeostasis, providing new perspectives for skeletal-related field research. In recent years, bone immunology has gradually become a hot spot in the study of bone-related diseases. As a new branch of immunology, bone immunology emphasizes that the immune system can directly or indirectly affect bones through the RANKL/RANK/OPG signaling pathway, IL family, TNF-α, TGF-β, and IFN-γ. These effects are of great significance for understanding inflammatory bone loss caused by various autoimmune or infectious diseases. In addition, as an external environment that plays an important role in immunity and bone, this study pays attention to the role of exercise-mediated bone immunity in bone reconstruction.

Role of MAPKs in TGF-β1-induced maturation and mineralization in human osteoblast-like cells

OBJECTIVES

Our study aimed to clarify the role of mitogen-activated protein kinases (MAPKs) in transforming growth factor (TGF)-β1-stimulated mineralization in the human osteoblast-like MG63 cells.

METHODS

The viability of MG63 cells under TGF-β1 stimulation was assessed by MTS assay. Western blotting determined TGF-β1-mediated activation of extracellular signal-related protein kinase (ERK), p38, and c-Jun amino-terminal kinase (JNK). Mineralization-related gene expression was examined by quantitative real-time PCR, and mineral deposition levels were evaluated by alizarin red S staining.

RESULTS

TGF-β1 had no effect on MG63 cell proliferation. Activation of p38 was observed at 3 h post TGF-β1 stimulation. Moreover, JNK phosphorylation was upregulated by TGF-β1 from 1 to 6 h post stimulation, but had no activation on ERK phosphorylation throughout the experimental period. Treatment with JNK inhibitor diminished the alizarin red S-stained area in a dose-dependent manner. Mineral deposition was unaffected by MEK inhibitor, whereas p38 inhibitor increased the red-stained area. Gene expression levels of ALP and BSP were significantly decreased under treatment with JNK inhibitor and p38 inhibitor. The MEK inhibitor had no effect on the TGF-β1-mediated upregulation of ALP and BSP. Although all three inhibitors suppressed expression of COL I, none were found to stimulate expression of OCN.

CONCLUSIONS

Human osteoblast-like MG63 cells maturation and mineralization are induced through JNK activation of MAPK signaling in response to TGF-β1.

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.

Mitigation of acute radiation syndrome (ARS) with human umbilical cord blood

PURPOSE

The growing concern over potential unintended nuclear accidents or malicious activities involving nuclear/radiological devices cannot be overstated. Exposure to whole-body doses of radiation can result in acute radiation syndrome (ARS), colloquially known as "radiation sickness," which can severely damage various organ systems. Long-term health consequences, such as cancer and cardiovascular disease, can develop many years post-exposure. Identifying effective medical countermeasures and devising a strategic medical plan represents an urgent, unmet need. Various clinical studies have investigated the therapeutic use of umbilical cord blood (UCB) for a range of illnesses, including ARS. The objective of this review is to thoroughly discuss ARS and its sub-syndromes, and to highlight recent findings regarding the use of UCB for radiation injury. UCB, a rich source of stem cells, boasts numerous advantages over other stem cell sources, like bone marrow, owing to its ease of collection and relatively low risk of severe graft-versus-host disease. Preclinical studies suggest that treatment with UCB, and often UCB-derived mesenchymal stromal cells (MSCs), results in improved survival, accelerated hematopoietic recovery, reduced gastrointestinal tract damage, and mitigation of radiation-induced pneumonitis and pulmonary fibrosis. Interestingly, recent evidence suggests that UCB-derived exosomes and their microRNAs (miRNAs) might assist in treating radiation-induced damage, largely by inhibiting fibrotic pathways.

CONCLUSION

UCB holds substantial potential as a radiation countermeasure, and future research should focus on establishing treatment parameters for ARS victims.

Converse modulation of Wnt/β-catenin signaling during expansion and differentiation phases of Infrapatellar fat pad-derived MSCs for improved engineering of hyaline cartilage

Mesenchymal stem cells (MSCs) are potential candidates in cell-based therapy for cartilage repair and regeneration. However, during chondrogenic differentiation, MSCs undergo undesirable hypertrophic maturation. This poses a risk of ossification in the neo-tissue formed that eventually impedes the clinical use of MSCs for cartilage repair. TGF-β is a potent growth factor used for chondrogenic differentiation of MSCs, however, its role in hypertrophy remains ambiguous. In the present work, we decipher that TGF-β activates Wnt/β-catenin signaling through SMAD3 and increases the propensity of Infrapatellar fat pad derived MSCs (IFP-MSCs) towards hypertrophy. Notably, inhibiting TGF-β induced Wnt/β-catenin signaling suppresses hypertrophic progression and enhances chondrogenic ability of IFP-MSCs in plasma hydrogels. Additionally, we demonstrate that activating Wnt signaling during expansion phase, promotes proliferation and reduces senescence, while improving stemness of IFP-MSCs. Thus, conversely modulating Wnt signaling in vitro during expansion and differentiation phases generates hyaline-like cartilage with minimal hypertrophy. Importantly, pre-treatment of IFP-MSCs encapsulated in plasma hydrogel with Wnt modulators followed by subcutaneous implantation in nude mice resulted in formation of a cartilage tissue with negligible calcification. Overall, this study provides technological advancement on targeting Wnt/β-catenin pathway in a 3D scaffold, while maintaining the standard chondro-induction protocol to overcome the challenges associated with the clinical use of MSCs to engineer hyaline cartilage.

Treatment with YIGSR peptide ameliorates mouse tail lymphedema by 67 kDa laminin receptor (67LR)-dependent cell-cell adhesion

Impaired microcirculation can cause lymphatic leakage which leads to a chronic swelling in the tissues of the body. However, no successful treatment gives any protection against lymphedema due to the lack of well-revealed pathophysiology of secondary lymphedema. Binary image of laminin immunohistochemical expression revealed that distribution of laminin expression localized during surgically induced lymphedema. 67 kDa laminin receptor (67LR) mRNA expression showed a peak at during lymphedema exacerbation. Since the response of 67LR molecules may affect the prevention of inflammation and edema, here we have hypothesized that 67LR ligand of YIGSR peptide could permit reconstructive environment for amelioration of lymphedema and evaluated the effect of YIGSR in a mouse tail model of lymphedema. Indeed, intra-abdominal injections of YIGSR for the first 3 days after inducing lymphedema in the mouse tail model reduced the tail lymphedema on day 14 by 27% (P = 0.035). Histology showed that YIGSR treatment protected lymphedema impairment in epidermis and dermis, and it also inhibited the expansion of intercellular spaces and enhanced especially cell adhesion in the basement membrane as revealed by transmission electron microscopy. Interestingly, the treatment also reduced the local expression of transforming growth factor (TGF)β. Further elucidation of the mechanisms of 67LR-facilitated lymphangiogenesis contributes to find potential targets for the treatment of lymphedema.

Adipokines regulate mesenchymal stem cell osteogenic differentiation

Mesenchymal stem cells (MSCs) can differentiate into various tissue cell types including bone, adipose, cartilage, and muscle. Among those, osteogenic differentiation of MSCs has been widely explored in many bone tissue engineering studies. Moreover, the conditions and methods of inducing osteogenic differentiation of MSCs are continuously advancing. Recently, with the gradual recognition of adipokines, the research on their involvement in different pathophysiological processes of the body is also deepening including lipid metabolism, inflammation, immune regulation, energy disorders, and bone homeostasis. At the same time, the role of adipokines in the osteogenic differentiation of MSCs has been gradually described more completely. Therefore, this paper reviewed the evidence of the role of adipokines in the osteogenic differentiation of MSCs, emphasizing bone formation and bone regeneration.

Human umbilical cord mesenchymal stem cells induction in peri-implantitis Rattus norvegicus accelerates and enhances osteogenesis activity and implant osseointegration

Peri-implantitis additional treatment generally aims to repair damaged tissue through a regenerative approach. Human umbilical cord mesenchymal stem cells (hUCMSCs) produce a high osteogenic effect and are capable of modulating the immune system by suppressing inflammatory response, modulating bone resorption, and inducing endogenous osteogenesis.

AIM

This study was intended to discover the effect of hUCMSCs on an implant osseointegration process in peri-implantitis rat subjects as assessed by several markers including interleukin-10 (IL-10), transforming growth factor-β (TGF-β), receptor activator of nuclear factor kappa- β ligand (RANKL), bone morphogenic protein (BMP-2), osterix (Osx), and osteoprotegerin (OPG).

MATERIAL AND METHODS

The research design implemented during this study represented a true experimental design incorporating the use of Rattus norvegicus (Wistar strain) as subjects.

RESULTS

Data analysed by means of a Brown Forsythe test indicated differences between the increase in BMP-2 expression (p < 0.000) and Osx expression (p < 0.001) and between RANKL expression (p < 0.001, Tukey HSD) and OPG expression (p < 0.000, Games Howell).

CONCLUSION

According to the findings of this research, hUCMSCs induction is successful in accelerating and enhancing osteogenic activity and implant osseointegration in peri-implantitis rat subjects.

Metabolic Switch Under Glucose Deprivation Leading to Discovery of NR2F1 as a Stimulus of Osteoblast Differentiation

Poor survival of grafted cells is the major impediment of successful cell-based therapies for bone regeneration. Implanted cells undergo rapid death in an ischemic environment largely because of hypoxia and metabolic stress from glucose deficiency. Understanding the intracellular metabolic processes and finding genes that can improve cell survival in these inhospitable conditions are necessary to enhance the success of cell therapies. Thus, the purpose of this study was to investigate changes of metabolic profile in glucose-deprived human bone marrow stromal/stem cells (hBMSCs) through metabolomics analysis and discover genes that could promote cell survival and osteogenic differentiation in a glucose-deprived microenvironment. Metabolomics analysis was performed to determine metabolic changes in a glucose stress metabolic model. In the absence of glucose, expression levels of all metabolites involved in glycolysis were significantly decreased than those in a glucose-supplemented state. In glucose-deprived osteogenic differentiation, reliance on tricarboxylic acid cycle (TCA)-predicted oxidative phosphorylation instead of glycolysis as the main mechanism for energy production in osteogenic induction. By comparing differentially expressed genes between glucose-deprived and glucose-supplemented hBMSCs, NR2F1 (Nuclear Receptor Subfamily 2 Group F Member 1) gene was discovered to be associated with enhanced survival and osteogenic differentiation in cells under metabolic stress. Small, interfering RNA (siRNA) for NR2F1 reduced cell viability and osteogenic differentiation of hBMSCs under glucose-supplemented conditions whereas NR2F1 overexpression enhanced osteogenic differentiation and cell survival of hBMSCs in glucose-deprived osteogenic conditions via the protein kinase B (AKT)/extracellular signal-regulated kinase (ERK) pathway. NR2F1-transfected hBMSCs significantly enhanced new bone formation in a critical size long-bone defect of rats compared with control vector-transfected hBMSCs. In conclusion, the results of this study provide an understanding of the metabolic profile of implanted cells in an ischemic microenvironment and demonstrate that NR2F1 treatment may overcome this deprivation by enhancing AKT and ERK regulation. These findings can be utilized in regenerative medicine for bone regeneration. © 2022 American Society for Bone and Mineral Research (ASBMR).

Effect of Ulinastatin on Syndecan-2-Mediated Vascular Damage in IDH2-Deficient Endothelial Cells

Syndecan-2 (SDC2), a cell-surface heparin sulfate proteoglycan of the glycocalyx, is mainly expressed in endothelial cells. Although oxidative stress and inflammatory mediators have been shown to mediate dysfunction of the glycocalyx, little is known about their role in vascular endothelial cells. In this study, we aimed to identify the mechanism that regulates SDC2 expression in isocitrate dehydrogenase 2 (IDH2)-deficient endothelial cells, and to investigate the effect of ulinastatin (UTI) on this mechanism. We showed that knockdown of IDH2 induced SDC2 expression in human umbilical vein endothelial cells (HUVECs). Matrix metalloproteinase 7 (MMP7) influences SDC2 expression. When IDH2 was downregulated, MMP7 expression was increased, as was TGF-β signaling, which regulates MMP7. Inhibition of MMP7 activity using MMP inhibitor II significantly reduced SDC2, suggesting that IDH2 mediated SDC2 expression via MMP7. Moreover, expression of SDC2 and MMP7, as well as TGF-β signaling, increased in response to IDH2 deficiency, and treatment with UTI reversed this increase. Similarly, the increase in SDC2, MMP7, and TGF-β signaling in the aorta of IDH2 knockout mice was reversed by UTI treatment. These findings suggest that IDH2 deficiency induces SDC2 expression via TGF-β and MMP7 signaling in endothelial cells.

Infection by High-Risk Human Papillomaviruses, Epithelial-to-Mesenchymal Transition and Squamous Pre-Malignant or Malignant Lesions of the Uterine Cervix: A Series of Chained Events?

Wound healing requires static epithelial cells to gradually assume a mobile phenotype through a multi-step process termed epithelial-to-mesenchymal transition (EMT). Although it is inherently transient and reversible, EMT perdures and is abnormally activated when the epithelium is chronically exposed to pathogens: this event deeply alters the tissue and eventually contributes to the development of diseases. Among the many of them is uterine cervical squamous cell carcinoma (SCC), the most frequent malignancy of the female genital system. SCC, whose onset is associated with the persistent infection of the uterine cervix by high-risk human papillomaviruses (HR-HPVs), often relapses and/or metastasizes, being resistant to conventional chemo- or radiotherapy. Given that these fearsome clinical features may stem, at least in part, from the exacerbated and long-lasting EMT occurring in the HPV-infected cervix; here we have reviewed published studies concerning the impact that HPV oncoproteins, cellular tumor suppressors, regulators of gene expression, inflammatory cytokines or growth factors, and the interactions among these effectors have on EMT induction and cervical carcinogenesis. It is predictable and desirable that a broader comprehension of the role that EMT inducers play in SCC pathogenesis will provide indications to flourish new strategies directed against this aggressive tumor.

The periosteum: a simple tissue with many faces, with special reference to the antler-lineage periostea

Periosteum is a thin membrane covering bone surfaces and consists of two layers: outer fibrous layer and inner cambium layer. Simple appearance of periosteum has belied its own complexity as a composite structure for physical bone protection, mechano-sensor for sensing mechanical loading, reservoir of biochemical molecules for initiating cascade signaling, niche of osteogenic cells for bone formation and repair, and "umbilical cord" for nourishing bone tissue. Periosteum-derived cells (PDCs) have stem cell attributes: self-renewal (no signs of senescence until 80 population doublings) and multipotency (differentiate into fibroblasts, osteoblasts, chondrocytes, adipocytes and skeletal myocytes). In this review, we summarized the currently available knowledge about periosteum and with special references to antler-lineage periostea, and demonstrated that although periosteum is a type of simple tissue in appearance, with multiple faces in functions; antler-lineage periostea add another dimension to the properties of somatic periostea: capable of initiation of ectopic organ formation upon transplantation and full mammalian organ regeneration when interacted with the covering skin. Very recently, we have translated this finding into other mammals, i.e. successfully induced partial regeneration of the amputated rat legs. We believe further refinement along this line would greatly benefit human health.

Mesenchymal Stem Cells and Extracellular Vesicles in Osteosarcoma Pathogenesis and Therapy

Osteosarcoma (OS) is an aggressive bone tumor that mainly affects children and adolescents. OS has a strong tendency to relapse and metastasize, resulting in poor prognosis and survival. The high heterogeneity and genetic complexity of OS make it challenging to identify new therapeutic targets. Mesenchymal stem cells (MSCs) are multipotent stem cells that can differentiate into adipocytes, osteoblasts, or chondroblasts. OS is thought to originate at some stage in the differentiation process of MSC to pre-osteoblast or from osteoblast precursors. MSCs contribute to OS progression by interacting with tumor cells via paracrine signaling and affect tumor cell proliferation, invasion, angiogenesis, immune response, and metastasis. Extracellular vesicles (EVs), secreted by OS cells and MSCs in the tumor microenvironment, are crucial mediators of intercellular communication, driving OS progression by transferring miRNAs/RNA and proteins to other cells. MSC-derived EVs have both pro-tumor and anti-tumor effects on OS progression. MSC-EVs can be also engineered to deliver anti-tumor cargo to the tumor site, which offers potential applications in MSC-EV-based OS treatment. In this review, we highlight the role of MSCs in OS, with a focus on EV-mediated communication between OS cells and MSCs and their role in OS pathogenesis and therapy.

The roles of metastasis-related proteins in the development of giant cell tumor of bone, osteosarcoma and Ewing's sarcoma

BACKGROUND:

Giant cell tumor of bone (GC), osteosarcoma (OS) and Ewing’s sarcoma (ES) are three different types of bone cancer with common and specific pathology features.

OBJECTIVE:

The purpose of the study was to examine the relationship and differences of the three bone tumors using clinical samples.

METHODS:

Through screening the profiles of clinical samples from GC, OS and ES patients using a humanoncology array, we found 26, 25 and 15 tumorigenesis factors significantly increased in GS, OS and ES tissues compared to normal individuals. eNOS, endostatin, HIF-1α, IL-6, CCL2/MCP-1, CCL8/MCP-2, CCL7/MCP-3, Tie and VEGF directly or indirectly involve in the metastasis Therefore, expression levels of the 6 factors were further determined by Western blot.

RESULTS:

The results showed levels of MCP1, MCP2, MCP3 or IL-6 in the GS, OS and ES significantly increased, and the expression levels of angiogenesis and anti-angiogenesis factors containing eNOS, endostatin, HIF-1α, Tie or VEGF were enhanced.

CONCLUSIONS:

Our results suggest that eNOS, endostatin, HIF-1α, IL-6, CCL2/MCP-1, CCL8/MCP-2, CCL7/MCP-3, Tie and VEGF may play important roles in tumorigenesis, reveal the expression differences of tumor-associated cytokines and angiogenesis related factors, and provide clinical evidence for studying the mechanisms on the metastasis in GC, OS and ES.

Reduction of mechanical loading in tendons induces heterotopic ossification and activation of the β-catenin signaling pathway

Background

Tendons are the force transferring tissue that enable joint movement. Excessive mechanical loading is commonly considered as a primary factor causing tendinopathy, however, an increasing body of evidence supports the hypothesis that overloading creates microdamage of collagen fibers resulting in a localized decreased loading on the cell population within the damaged site. Heterotopic ossification is a complication of late stage tendinopathy, which can significantly affect the mechanical properties and homeostasis of the tendon. Here, we the examine the effect of mechanical underloading on tendon ossification and investigate its underlying molecular mechanism.

Method

Rabbit Achilles tendons were dissected and cultured in an underloading environment (3% cyclic tensile stain,0.25 ​Hz, 8 ​h/day) for either 10, 15 or 20 days. Using isolated tendon-derived stem cells (TDSCs) 3D constructs were generated, cultured and subjected to an underloading environment for 6 days. Histological assessments were performed to evaluate the structure of the 3D constructs; qPCR and immunohistochemistry were employed to study TDSC differentiation and the β-catenin signal pathway was investigated by Western blotting. Mechanical testing was used to determine ability of the tendon to withstand force generation.

Result

Tendons cultured for extended times in an environment of underloading showed progressive heterotopic ossification and a reduction in biomechanical strength. qPCR revealed that 3D TDSCs constructs cultured in an underloading environment exhibited increased expression of several osteogenic genes: these include RUNX2, ALP and osteocalcin in comparison to tenogenic differentiation markers (scleraxis and tenomodulin). Immunohistochemical analysis further confirmed high osteocalcin production in 3D TDSCs constructs subject to underloading. Western blotting of TDSC constructs revealed that β-catenin accumulation and translocation were associated with an increase in phosphorylation at Ser552 and decrease phosphorylation at Ser33.

Conclusion

These findings unveil a potential mechanism for heterotopic ossification in tendinopathy due to the underloading of TDSCs at the damage sites, and also that β-catenin could be a potential target for treating heterotopic ossification in tendons.

The Translational potential

Tendon heterotopic ossification detrimentally affect quality of life especially for those who has atheletic career. This study reveals the possible mechanism of heterotpic ossification in tendon related to mechanical loading. This study provided the possible to develop a mechanical stimulation protocol for preventive and therapeutic purpose for tendon heterotopic ossification.

Bone Cells Differentiation: How CFTR Mutations May Rule the Game of Stem Cells Commitment?

Cystic fibrosis (CF)-related bone disease has emerged as a significant comorbidity of CF and is characterized by decreased bone formation and increased bone resorption. Both osteoblast and osteoclast differentiations are impacted by cystic fibrosis transmembrane conductance regulator (CFTR) mutations. The defect of CFTR chloride channel or the loss of CFTRs ability to interact with other proteins affect several signaling pathways involved in stem cell differentiation and the commitment of these cells toward bone lineages. Specifically, TGF-, nuclear factor-kappa B (NF-B), PI3K/AKT, and MAPK/ERK signaling are disturbed by CFTR mutations, thus perturbing stem cell differentiation. High inflammation in patients changes myeloid lineage secretion, affecting both myeloid and mesenchymal differentiation. In osteoblast, Wnt signaling is impacted, resulting in consequences for both bone formation and resorption. Finally, CFTR could also have a direct role in osteoclasts resorptive function. In this review, we summarize the existing literature on the role of CFTR mutations on the commitment of induced pluripotent stem cells to bone cells.

Glucose Metabolism in Osteoblasts in Healthy and Pathophysiological Conditions

Bone tissue in vertebrates is essential to performing movements, to protecting internal organs and to regulating calcium homeostasis. Moreover, bone has also been suggested to contribute to whole-body physiology as an endocrine organ, affecting male fertility; brain development and cognition; and glucose metabolism. A main determinant of bone quality is the constant remodeling carried out by osteoblasts and osteoclasts, a process consuming vast amounts of energy. In turn, clinical conditions associated with impaired glucose metabolism, including type I and type II diabetes and anorexia nervosa, are associated with impaired bone turnover. As osteoblasts are required for collagen synthesis and matrix mineralization, they represent one of the most important targets for pharmacological augmentation of bone mass. To fulfill their function, osteoblasts primarily utilize glucose through aerobic glycolysis, a process which is regulated by various molecular switches and generates adenosine triphosphate rapidly. In this regard, researchers have been investigating the complex processes of energy utilization in osteoblasts in recent years, not only to improve bone turnover in metabolic disease, but also to identify novel treatment options for primary bone diseases. This review focuses on the metabolism of glucose in osteoblasts in physiological and pathophysiological conditions.

Multiomics analyses of cytokines, genes, miRNA, and regulatory networks in human mesenchymal stem cells expanded in stirred microcarrier-spinner cultures

Mesenchymal stem cells (MSCs) are of great clinical interest as a form of allogenic therapy due to their excellent regenerative and immunomodulatory effects for various therapeutic indications. Stirred suspension bioreactors using microcarriers (MC) have been used for large-scale production of MSCs compared to planar cultivation systems. Previously, we have demonstrated that expansion of MSCs in MC-spinner cultures improved chondrogenic, osteogenic, and cell migration potentials as compared to monolayer-static cultures. In this study, we sought to address this by analyzing global gene expression patterns, miRNA profiles and secretome under both monolayer-static and MC-spinner cultures in serum-free medium at different growth phases. The datasets revealed differential expression patterns that correlated with potentially improved MSC properties in cells from MC-spinner cultures compared to those of monolayer-static cultures. Transcriptome analysis identified a unique expression signature for cells from MC-spinner cultures, which correlated well with miRNA expression, and cytokine secretion involved in key MSC functions. Importantly, MC-spinner cultures and conditioned medium showed increased expression of factors that possibly enhance pathways of extracellular matrix dynamics, cellular metabolism, differentiation potential, immunoregulatory function, and wound healing. This systematic analysis provides insights for the efficient optimization of stem cell bioprocessing and infers that MC-based bioprocess manufacturing could improve post-expansion cellular properties for stem cell therapies.

miR300 intervenes Smad3/β-catenin/RunX2 crosstalk for therapy with an alternate function as indicative biomarker in osteoporosis

The study reports a theranostic nature of rno-miR-300 (miR300) in the osteoblast functioning, by influencing the signaling pathway(s), associated with osteoblast differentiation. Excessive expression of miR300 suppresses osteoblast functions. Smad3 served as a validated target for miR300, on homology-based computational analysis and experimental testimony, which activates β-catenin, and subsequently potentiates Runx2. The impact of miR300 on the Smad3/β-catenin/Runx2 signaling interactions in the induction of osteoblast differentiation was scrutinized by immunoblotting and in vivo miRNA antagonism. Overexpression of miR300 in the rat calvarial osteoblasts decreases the protein levels of Smad3, β-catenin and Runx2. Besides, in vivo silencing of miR300 in the neonatal pups and adult rats by AntimiR300 abolishes the suppressing action of miR300 on the osteoblast differentiation and expressions of Smad3/β-catenin/Runx2 axis. MicroCT studies showed improved trabecular microarchitecture in the AntimiR300 transfected ovariectomised rat model compared to sham and negative control. Furthermore, expression levels of miR300 were evaluated in serum samples from an independent set of 30 osteoporotic patients followed by a Receiver Operating Characteristic Curve (ROC) based analysis for the diagnostic efficiency of miR300. Interestingly, the results exhibited high levels of miR300 (p < 0.0001) in the serum samples from osteoporotic patients relative to non-osteoporotic subjects (AUC = 0.9689). Thus, miR300 negatively regulates the differentiation of osteoblasts by targeting crosstalk among Smad3, β-catenin and Runx2, unveiling an enormous ability to serve as a therapeutic target for bone-related disorder management strategies. Besides, miR300 may potentially function for the diagnosis of osteoporosis as a non-invasive biomarker.

Chrysin induces osteogenic differentiation of human dental pulp stem cells

OBJECTIVES

As an ideal cell source for tissue engineering and bone defect repair, dental pulp stem cells (DPSCs) have good osteogenic differentiation potential. Chrysin, a flavonoid extracted from oroxylum seeds, has been proven to promote bone formation of bone marrow stem cells. However, the effect of chrysin on osteogenic differentiation of DPSCs remains unclear. This study aimed to investigate the role of Chrysin in promoting osteogenic differentiation of DPSCs and in DPSC-based bone formation.

MATERIAL AND METHODS

We investigated the effects of chrysin on DPSCs from patients by CCK-8 assay, Alizarin Red S staining, qPCR and Western blotting. The effects of chrysin on DPSC-based bone formation in a heterotopic osteogenesis model in nude mice and a rat calvarial defect model were also performed. Finally, we investigated the mechanism of chrysin-treated DPSCs by proteomics.

RESULTS

Chrysin upregulated the expression of osteogenic proteins and induced osteogenic differentiation of DPSCs. Moreover, chrysin induced abundant β-TCP-induced formation of mineralized bone tissue and promoted DPSC-based bone formation in a heterotopic osteogenesis model in nude mice and a rat calvarial defect model. Proteomics showed that upregulation of the Smad3 was closely related to osteogenic differentiation. Inhibiting of Smad3 activation by a Smad3 inhibitor could reverse the chrysin-mediated increases in the expression levels of osteogenic genes and osteogenic induction of DPSCs.

CONCLUSIONS

Our study implies the intriguing potential of chrysin-treated DPSCs in bone regeneration and bone defect repair.

Influence of the TGF-β Superfamily on Osteoclasts/Osteoblasts Balance in Physiological and Pathological Bone Conditions

The balance between bone forming cells (osteoblasts/osteocytes) and bone resorbing cells (osteoclasts) plays a crucial role in tissue homeostasis and bone repair. Several hormones, cytokines, and growth factors-in particular the members of the TGF-β superfamily such as the bone morphogenetic proteins-not only regulate the proliferation, differentiation, and functioning of these cells, but also coordinate the communication between them to ensure an appropriate response. Therefore, this review focuses on TGF-β superfamily and its influence on bone formation and repair, through the regulation of osteoclastogenesis, osteogenic differentiation of stem cells, and osteoblasts/osteoclasts balance. After introducing the main types of bone cells, their differentiation and cooperation during bone remodeling and fracture healing processes are discussed. Then, the TGF-β superfamily, its signaling via canonical and non-canonical pathways, as well as its regulation by Wnt/Notch or microRNAs are described and discussed. Its important role in bone homeostasis, repair, or disease is also highlighted. Finally, the clinical therapeutic uses of members of the TGF-β superfamily and their associated complications are debated.

Tissue-specific mesenchymal stem cell-dependent osteogenesis in highly porous chitosan-based bone analogs

Among conventional fabrication techniques, freeze‐drying process has widely been investigated for polymeric implants. However, the understanding of the stem cell progenitor‐dependent cell functionality modulation and quantitative analysis of early osseointegration of highly porous scaffolds have not been explored. Here, we developed a novel, highly porous, multimaterial composite, chitosan/hydroxyapatite/polycaprolactone (CHT/HA/PCL). The in vitro studies have been performed using mesenchymal stem cells (MSCs) from three tissue sources: human bone marrow‐derived MSCs (BM‐MSCs), adipose‐derived MSCs (AD‐MSCs), and Wharton's jelly‐derived MSCs (WJ‐MSCs). Although cell attachment and metabolic activity [3‐4,5‐dimethylthiazol‐2yl‐(2,5 diphenyl‐2H‐tetrazoliumbromide) assay] were ore enhanced in WJ‐MSC‐laden CHT/HA/PCL composites, scanning electron microscopy, real‐time gene expression (alkaline phosphatase [ALP], collagen type I [Col I], osteocalcin [OCN], and bone morphogenetic protein 4 [BMP‐4]), and immunostaining (COL I, β‐CATENIN, OCN, and SCLEROSTIN [SOST]) demonstrated pronounced osteogenesis with terminal differentiation on BM‐MSC‐laden CHT/HA/PCL composites only. The enhanced cell functionality on CHT/HA/PCL composites was explained in terms of interplay among the surface properties and the optimal source of MSCs. In addition, osteogenesis in rat tibial model over 6 weeks confirmed a better ratio of bone volume to the total volume for BM‐MSC‐laden composites over scaffold‐only and defect‐only groups. The clinically conformant combination of 3D porous architecture with pore sizes varying in the range of 20 to 200  μm together with controlled in vitro degradation and early osseointegration establish the potential of CHT/HA/PCL composite as a potential cancellous bone analog.

Comparative Secretome Analysis of Mesenchymal Stem Cells From Dental Apical Papilla and Bone Marrow During Early Odonto/Osteogenic Differentiation: Potential Role of Transforming Growth Factor-β2

To understand the functions of secretory proteins in odontogenesis and to further the understanding of the different molecular events during odontogenesis and osteogenesis, we induced the odonto/osteogenic differentiation of stem cells from dental apical papilla (SCAPs) and bone marrow-derived stem cells (BMSCs) in vitro and compared the expression of secretory proteins during early odonto/osteogenic differentiation using high-performance liquid chromatography with tandem mass spectrometry. The results revealed significant changes by at least 50% in 139 SCAP proteins and 203 BMSC proteins during differentiation. Of these, 92 were significantly upregulated and 47 were significantly downregulated during the differentiation of SCAPs. Most of these proteins showed the same trend during the differentiation of BMSCs. Among the proteins that showed significantly changes during the differentiation of SCAPs and BMSCs, we found that transforming growth factor-β2 (TGFβ2) is a key protein in the network with powerful mediation ability. TGFβ2 was secreted more by SCAPs than BMSCs, was significantly upregulated during the differentiation of SCAPs and was significantly downregulated during the differentiation of BMSCs. Furthermore, the effects of recombinant human TGFβ2 and TGFβ1 on the odonto/osteogenic differentiation of SCAPs and BMSCs were investigated. Real-time reverse transcription polymerase chain reaction (RT-PCR) and western blotting data revealed that TGFβ2 enhanced the odontogenic-related markers [dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1)] and inhibited the osteogenic-related marker bone sialoprotein (BSP) in SCAPs, whereas TGFβ1 enhanced the BSP expression and inhibited the DSPP and DMP1 expression at early odonto/osteogenic differentiation of SCAPs. However, in BMSCs, TGFβ2 enhanced the expression of alkaline phosphatase (ALP), runt-related transcription factor 2 (RUNX2), DSPP, and DMP1, whereas TGFβ1 enhanced the expression of ALP and RUNX2, with no significant intergroup difference of DSPP at the early odonto/osteogenic differentiation of BMSCs. TGFβ2 is a potentially important molecule with a distinct function in the regulation of odontogenesis and osteogenesis.

Mapping the structure and biological functions within mesenchymal bodies using microfluidics

Organoids that recapitulate the functional hallmarks of anatomic structures comprise cell populations able to self-organize cohesively in 3D. However, the rules underlying organoid formation in vitro remain poorly understood because a correlative analysis of individual cell fate and spatial organization has been challenging. Here, we use a novel microfluidics platform to investigate the mechanisms determining the formation of organoids by human mesenchymal stromal cells that recapitulate the early steps of condensation initiating bone repair in vivo. We find that heterogeneous mesenchymal stromal cells self-organize in 3D in a developmentally hierarchical manner. We demonstrate a link between structural organization and local regulation of specific molecular signaling pathways such as NF-κB and actin polymerization, which modulate osteo-endocrine functions. This study emphasizes the importance of resolving spatial heterogeneities within cellular aggregates to link organization and functional properties, enabling a better understanding of the mechanisms controlling organoid formation, relevant to organogenesis and tissue repair.

Impact of fecal microbiota transplantation on TGF-β1/Smads/ERK signaling pathway of endotoxic acute lung injury in rats

Acute lung injury (ALI) is a common clinical disease with high morbidity in both humans and animals. Studies have shown that intestinal microbiota affect the pathology and immune function of respiratory diseases through the "gut-lung axis". The authors investigated the therapeutic effect of fecal microbiota transplantation (FMT) in rats with ALI induced by lipopolysaccharide (LPS). Rats were treated with FMT, and then measured lung wet/dry ratio, PaO₂ in artery, proinflammatory marker, and TGF-β1, Smad3, Smad7, and phosphorylated ERK (p-ERK) protein levels, as well as a histopathologic analysis and high-throughput sequencing of intestinal microbiota. FMT significantly reduced lung wet/dry ratio and TNF-α, IL-1β, and IL-6 levels, but increased the levels of PaO₂ in artery. In addition, FMT significantly decreased the expression of TGF-β1, Smad3, and p-ERK, while increased the levels of Smad7. Lung histopathological analyses showed that FMT reduced the inflammatory cell infiltration and interstitial lung exudates. High-throughput sequencing of intestinal microbiota analyses showed that FMT reconstructed the structure of intestinal microbiota, and increased the gene abundance of the bacterial community. Therefore, FMT may act on the TGF-β1/Smads/ERK pathway by regulating intestinal microbiota, inhibiting immune inflammation, reducing the production of inflammatory markers in the body and release, and reducing alveolar epithelial damage and repair, thereby improving the endotoxic ALI in rats induced by LPS.

Concise Review: The Regulatory Mechanism of Lysine Acetylation in Mesenchymal Stem Cell Differentiation

Nowadays, the use of MSCs has attracted considerable attention in the global science and technology field, with the self-renewal and multidirectional differentiation potential for diabetes, obesity treatment, bone repair, nerve repair, myocardial repair, and so on. Epigenetics plays an important role in the regulation of mesenchymal stem cell differentiation, which has become a research hotspot in the medical field. This review focuses on the role of lysine acetylation modification on the determination of MSC differentiation direction. During this progress, the recruitment of lysine acetyltransferases (KATs) and lysine deacetylases (KDACs) is the crux of transcriptional mechanisms in the dynamic regulation of key genes controlling MSC multidirectional differentiation.

Osteoclasts degrade fibrinogen scaffolds and induce mesenchymal stem/stromal osteogenic differentiation

Fibrinogen (Fg) is a pro-inflammatory protein with pro-healing properties. Previous work showed that fibrinogen 3D scaffolds (Fg-3D) promote bone regeneration, but the cellular players were not identified. Osteoclasts are bone resorbing cells that promote bone remodeling in close crosstalk with osteoblasts. Herein, the capacity of osteoclasts differentiated on Fg-3D to degrade the scaffolds and promote osteoblast differentiation was evaluated in vitro. Fg-3D scaffolds were prepared by freeze-drying and osteoclasts were differentiated from primary human peripheral blood monocytes. Results obtained showed osteoclasts expressing the enzymes cathepsin K and tartrate resistant acid phosphatase colonizing Fg-3D scaffolds. Osteoclasts were able to significantly degrade Fg-3D, reducing the scaffold's area, and increasing D-dimer concentration, a Fg degradation product, in their culture media. Osteoclast conditioned media from the first week of differentiation promoted significantly stronger human primary mesenchymal stem/stromal cell (MSC) osteogenic differentiation, evaluated by alkaline phosphatase activity. Moreover, week 1 osteoclast conditioned media promoted earlier MSC osteogenic differentiation, than chemical osteogenesis inductors. TGF-β1 was found increased in osteoclast conditioned media from week 1, when compared to week 3 of differentiation. Taken together, our results suggest that osteoclasts are able to differentiate and degrade Fg-3D, producing factors like TGF-β1 that promote MSC osteogenic differentiation.

Effect of TAK1 on osteogenic differentiation of mesenchymal stem cells by regulating BMP-2 via Wnt/β-catenin and MAPK pathway

Mesenchymal stem cells (MSCs) have the ability to differentiate into osteoblasts and chondrocytes. In vitro osteogenic differentiation is critical but the molecular mechanism has yet to be further clarified. The role of TGF-β activated kinase 1 (TAK1) in MSCs osteogenesis differentiation has not been reported. By adding si-TAK1 and rhTAK1, the osteogenic differentiation of MSCs was measured. Expression levels of the osteoblastic marker genes during osteogenic differentiation of MSCs were checked. As well as molecules involved in BMP and Wnt/β-catenin signaling pathways. The phosphorylation of p38 and JNK was also checked. TAK1 is essential for mineralization of MSCs at low concentration, but excessive rhTAK1 inhibits mineralization of MSCs. It up regulates the expression levels of bone sialoprotein (BSP), osteocalcin (OSC), Alkaline phosphatase (ALP), and RUNX2 during osteogenic differentiation of MSCs. It can also promote TGF-β/BMP-2 gene expression and β-catenin expression, and down regulate GSK-3β expression. Meanwhile, TAK1 promotes the phosphorylation of p38 and JNK. Additionally, TAK1 up regulates the expression of BMP-2 at all concentration under the inhibition of p38 and JNK. Our results suggested that TAK1 is essential in MSCs osteogenesis differentiation, and functions as a double-edged sword, probably through regulation of β-catenin and p38/JNK.

Biological functions of mesenchymal stem cells and clinical implications

Mesenchymal stem cells (MSCs) are isolated from multiple biological tissues-adult bone marrow and adipose tissues and neonatal tissues such as umbilical cord and placenta. In vitro, MSCs show biological features of extensive proliferation ability and multipotency. Moreover, MSCs have trophic, homing/migration and immunosuppression functions that have been demonstrated both in vitro and in vivo. A number of clinical trials are using MSCs for therapeutic interventions in severe degenerative and/or inflammatory diseases, including Crohn's disease and graft-versus-host disease, alone or in combination with other drugs. MSCs are promising for therapeutic applications given the ease in obtaining them, their genetic stability, their poor immunogenicity and their curative properties for tissue repair and immunomodulation. The success of MSC therapy in degenerative and/or inflammatory diseases might depend on the robustness of the biological functions of MSCs, which should be linked to their therapeutic potency. Here, we outline the fundamental and advanced concepts of MSC biological features and underline the biological functions of MSCs in their basic and translational aspects in therapy for degenerative and/or inflammatory diseases.

Mechanical and Mechanosensing Properties of Tumor Affected Bone Cells Were Inhibited via PI3K/Akt Pathway

Background

Osteolytic metastasis is a common destructive form of metastasis, in which there is an increased bone resorption but impaired bone formation. It is hypothesized that the changed mechanical properties of tumor affected bone cells could inhibit its mechanosensing, thus contributing to differences in bone remodeling.

Methods

Here, atomic force microscopy indentation on primary bone cells exposed to 50% conditioned medium from Walker 256 (W) carcinoma cell line or its adaptive tumor (T) cells was carried out. Nitric oxide levels of bone cells were monitored in response to low-magnitude, high-frequency (LMHF) vibrations.

Results

A stronger sustained inhibitive effect on bone cell viability and differentiation by T cells as compared to that of its cell line was demonstrated. This could be attributed to the higher levels of transforming growth factor-β1 (TGF-β1) in the T-conditioned medium as compared to W-conditioned medium. Bone cell elastic moduli in W and T-groups were found to decrease significantly by 61.0% and 69.6%, respectively compared to control and corresponded to filamentous actin changes. Nitric oxide responses were significantly inhibited in T-conditioned group but not in W-conditioned group.

Conclusions

It implied that a change in cell mechanical properties is not sufficient as an indicator of change in mechanosensing ability. Moreover, inhibition of phosphoinositide 3-kinase/Akt downstream signaling pathway of TGF-β1 alleviated the inhibition effects on mechanosensing in T-conditioned cells, further suggesting that growth factors such as TGF-β could be good therapeutic targets for osteoblast treatment.

Blocking Wnt as a therapeutic target in mice model of skin cancer

Wnt pathway plays an important role in controlling metabolism in cancer cells. It acts as positive modulator for both cell inflammation, through activation of NFκB, and fibrosis, through activation of TGF-β. Therefore, the aim of this study is to investigate the therapeutic effects of blocking Wnt pathway by IWP12 on skin cancer by studying its effects on skin cancer-induced inflammation and fibrosis in a mice model of skin cancer. Skin cancer was induced by application of 7,12-dimethylbenz[a]anthracene (DMBA) and croton oil on the dorsal skin of mice. Dorsal skin was removed for estimation of gene and protein expression of Wnt, β-catenin, SMAD, TGF-β, NFκB, TNF-α, IL-4 and IL-10. Part of the skin is stained with hematoxylin/eosin for assessment of cell structure. Treatment of mice with IWP12 completely blocked Wnt in skin cancer mice without affecting the control mice. Skin of tumorigenic mice showed marked skin hyperkeratosis, parakeratosis, acanthosis and dysplasia. Treatment with IWP12 markedly attenuated epidermal atypia and hyperplasia. In addition, IWP12 reduced expression of β-catenin, SMAD, TGF-β, NFκB and TNF-α associated with increase in the expression of IL-4 and IL-10. In conclusion, blocking Wnt production ameliorated skin cancer via blocking pro-inflammatory cytokines and enhancing the anti-inflammatory cytokines. Moreover, blocking Wnt attenuated skin cancer-induced activation of fibrosis pathway.

Identification of new therapeutic targets for osteoarthritis through genome-wide analyses of UK Biobank data

Osteoarthritis is the most common musculoskeletal disease and the leading cause of disability globally. Here, we perform a genome-wide association study for osteoarthritis (77,052 cases and 378,169 controls), analysing 4 phenotypes: knee osteoarthritis, hip osteoarthritis, knee and/or hip osteoarthritis, and any osteoarthritis. We discover 64 signals, 52 of them novel, more than doubling the number of established disease loci. Six signals fine map to a single variant. We identify putative effector genes by integrating eQTL colocalization, fine-mapping, human rare disease, animal model, and osteoarthritis tissue expression data. We find enrichment for genes underlying monogenic forms of bone development diseases, and for the collagen formation and extracellular matrix organisation biological pathways. Ten of the likely effector genes, including TGFB1, FGF18, CTSK and IL11 have therapeutics approved or in clinical trials, with mechanisms of action supportive of evaluation for efficacy in osteoarthritis.

Specific knockdown of HOXB7 inhibits cutaneous squamous cell carcinoma cell migration and invasion while inducing apoptosis via the Wnt/β-catenin signaling pathway

Metastatic cutaneous squamous cell carcinoma (CSCC) is a major cause of death associated with nonmelanoma skin cancer. The involvement of homeobox B7 ( HOXB7) in cancers has been reported. Thus, the current study intends to explore the effect of HOXB7 on CSCC and its relationship with the Wnt/β-catenin signaling pathway. Initially, microarray-based gene expression profiling of CSCC was performed, and HOXB7 was identified as an upregulated gene based on the microarray data of GSE66359 . Following this, the experimental results indicated that HOXB7 and β-catenin formed a composite, demonstrating that endogenous HOXB7 binds to β-catenin. Subsequently, CSCC cells were treated with siRNA against HOXB7 or an inhibitor of the Wnt/β-catenin signaling pathway to analyze any underlying regulatory mechanism of HOXB7 on the CSCC cells. Tumor growth involving xenografts in nude mice was also observed so as to explore whether or not HOXB7 could regulate subcutaneous tumor growth through in vivo culturing. To investigate the potential effects of HOXB7 on the Wnt/β-catenin signaling pathway, we determined the expression of HOXB7 and downstream genes of the Wnt/β-catenin signaling pathway. Notably, siRNA-mediated knockdown of HOXB7 inhibited the activation of the Wnt/β-catenin signaling pathway, thereby impeding the progression of cell viability, migration, and invasion as well as of the tumor growth, although contrarily facilitating cell apoptosis. Taken together, silencing of the HOXB7 has the mechanism of inactivating the Wnt/β-catenin signaling pathway, thereby accelerating cell apoptosis and suppressing cell migration and invasion in CSCC, which could provide a candidate target for the CSCC treatment.

NR2F1 mediated down-regulation of osteoblast differentiation was rescued by bone morphogenetic protein-2 (BMP-2) in human MSC

Endochondral ossification is the process by which long bones are formed; the process of long bone formation is regulated by numerous factors such as transcription factors, cytokines, and extracellular matrix molecules. Human hormone Nuclear receptors (hHNR) are a family of ligand-regulated transcription factors that are activated by steroid hormones, such as estrogen and progesterone, and various lipid-soluble signals, including retinoic acid, oxysterols, and thyroid hormone. Whole genome microarray data from our previous study revealed that most hHNR's are up-regulated during osteoblast differentiation in hMSCS. NR2F1 was among the highest expressed hHNR during osteogenesis, NR2F1 belongs to the steroid/thyroid hormone nuclear receptor superfamily. NR2F1 is designated as an orphan nuclear receptor because its ligands are unknown. NR2F1 plays a wide range of roles, including cell differentiation, cancer progression, and central and peripheral neurogenesis. Identifying signaling networks involved in osteoblast differentiation is important in orchestrating new therapeutic and clinical applications in bone biology. This study aimed to identify alterations in signaling networks mediated by NR2F1 in osteoblast differentiation. siRNA-mediated down-regulation of NR2F1 leads to impairment in the differentiation of hBMSC-TERT to osteoblast; gene-expression results confirmed the down-regulation of osteoblast markers such as RUNX2, ALPL, OSC, and BSP. Global whole gene expression analysis revealed that most down-regulated genes were associated with osteoblast differentiation (DDIT3, BMP2). Pathway analysis revealed prominent signaling pathways that were down-regulated, including the TGFβ pathway and MAPK pathway. Functional studies on NR2F1 transfected cells, during osteoblast differentiation in combination with TGFβ1 and BMP-2, showed that TGFβ1 does not recover osteoblast differentiation, whereas BMP-2 rescues osteoblast differentiation in NR2F1 siRNA transfected cells. Thus, our results showed that BMP-2 could intervene in NR2F1 down-regulated signaling pathways to recover osteoblast differentiation.

Thymosin β4 is associated with bone sialoprotein expression via ERK and Smad3 signaling pathways in MDPC-23 odontoblastic cells

Thymosin β4 (Tβ4) regulates the expression of molecules associated with dentinogenesis, including bone sialoprotein (BSP). BSP regulates the initiation of mineralization and the direction of dentin growth. However, the association between Tβ4 signaling and BSP expression in odontoblasts remains unclear. Therefore, the aim of the present study was to investigate Tβ4 mRNA expression in odontoblasts during dentinogenesis and the association between the Tβ4 signaling pathway and BSP expression in MDPC‑23 odontoblastic cells. Expression and localization of Tβ4 mRNA was determined by in situ hybridization during mouse tooth development. The effect of Tβ4 signaling on BSP expression was investigated by reverse transcription polymerase chain reaction, western blot analysis, immunofluorescence and a luciferase reporter assay in the presence or absence of specific inhibitors of mitogen activated protein kinase kinase (PD98059) and mothers against decapentaplegic homolog 3 (Smad3; SIS3) in MDPC‑23 cells. The expression of Tβ4 mRNA in the odontoblast layer was highest at postnatal day 5, known as the advanced bell stage, when odontoblasts actively secrete dentin matrix proteins. Tβ4 increased BSP mRNA and protein levels in MDPC‑23 cells, but this was inhibited by PD98059 or SIS3 treatment. Tβ4 increased levels of phosphorylated (p) extracellular signal‑regulated kinase (ERK)1/2, pSmad3, pβ‑catenin, and runt‑related transcription factor 2 (Runx2) protein, but these effects were inhibited by PD98059 or SIS3. Tβ4 induced the nuclear translocation of Runx2 and pSmad3, while nuclear translocation of β‑catenin was decreased. Tβ4 significantly increased BSP promoter activity, which was decreased by PD98059 or SIS3 treatment. Tβ4 induced BSP expression in MDPC‑23 cells via ERK and Smad3 signaling pathways, suggesting its role as a signaling molecule in odontoblasts for regulating BSP secretion during dentinogenesis.

TGF-Beta Signaling in Bone with Chronic Kidney Disease

Transforming growth factor (TGF)-β signaling is not only important in skeletal development, but also essential in bone remodeling in adult bone. The bone remodeling process involves integrated cell activities induced by multiple stimuli to balance bone resorption and bone formation. TGF-β plays a role in bone remodeling by coordinating cell activities to maintain bone homeostasis. However, mineral metabolism disturbance in chronic kidney disease (CKD) results in abnormal bone remodeling, which leads to ectopic calcification in CKD. High circulating levels of humoral factors such as parathyroid hormone, fibroblast growth factor 23, and Wnt inhibitors modulate bone remodeling in CKD. Several reports have revealed that TGF-β is involved in the production and functions of these factors in bone. TGF-β may act as a factor that mediates abnormal bone remodeling in CKD.

TGF-β and mesenchymal stromal cells in regenerative medicine, autoimmunity and cancer

Multipotent mesenchymal stromal cells (MSCs) represent a promising cell-based therapy in regenerative medicine and for the treatment of inflammatory/autoimmune diseases. Importantly, MSCs have emerged as an important contributor to the tumor stroma with both pro- and anti-tumorigenic effects. However, the successful translation of MSCs to the clinic and the prevention of their tumorigenic and metastatic effect require a greater understanding of factors controlling their proliferation, differentiation, migration and immunomodulation in vitro and in vivo. The transforming growth factor(TGF)-β1, 2 and 3 are involved in almost every aspect of MSC function. The aim of this review is to highlight the roles that TGF-β play in the biology and therapeutic applications of MSCs. We will discuss the how TGF-β modulate MSC function as well as the paracrine effects of MSC-derived TGF-β on other cell types in the context of tissue regeneration, immune responses and cancer. Finally, taking all these aspects into consideration we discuss how modulation of TGF-β signaling/production in MSCs could be of clinical interest.

TGF-β Family Signaling in Mesenchymal Differentiation

Mesenchymal stem cells (MSCs) can differentiate into several lineages during development and also contribute to tissue homeostasis and regeneration, although the requirements for both may be distinct. MSC lineage commitment and progression in differentiation are regulated by members of the transforming growth factor-β (TGF-β) family. This review focuses on the roles of TGF-β family signaling in mesenchymal lineage commitment and differentiation into osteoblasts, chondrocytes, myoblasts, adipocytes, and tenocytes. We summarize the reported findings of cell culture studies, animal models, and interactions with other signaling pathways and highlight how aberrations in TGF-β family signaling can drive human disease by affecting mesenchymal differentiation.

The Influence of Breast Tumour-Derived Factors and Wnt Antagonism on the Transformation of Adipose-Derived Mesenchymal Stem Cells into Tumour-Associated Fibroblasts

Within the tumour stroma, a heterogeneous population of cell types reciprocally regulates cell proliferation, which considerably affects the progression of the disease. In this study, using tumour conditioned medium (TCM) derived from breast tumour cell lines - MCF7 and MDA MB 231, we have demonstrated the differentiation of adipose-derived mesenchymal stem cells (ADSCs) into tumour-associated fibroblasts (TAFs). Since the Wnt signalling pathway is a key signalling pathway driving breast tumour growth, the effect of the Wnt antagonist secreted frizzled-related protein 4 (sFRP4) was also examined. The response of ADSCs to TCM and sFRP4 treatments was determined by using cell viability assay to determine the changes in ADSC viability, immunofluorescence for mesenchymal markers, glucose uptake assay, and glycolysis stress test using the Seahorse Extracellular Flux analyser to determine the glycolytic activity of ADSCs. ADSCs have been shown to acquire a hyper-proliferative state, significantly increasing their number upon short-term and long-term exposure to TCM. Changes have also been observed in the expression of key mesenchymal markers as well as in the metabolic state of ADSCs. SFRP4 significantly inhibited the differentiation of ADSCs into TAFs by reducing cell growth as well as mesenchymal marker expression (cell line-dependent). However, sFRP4 did not induce further significant changes to the altered metabolic phenotype of ADSCs following TCM exposure. Altogether, this study suggests that the breast tumour milieu may transform ADSCs into a tumour-supportive phenotype, which can be altered by Wnt antagonism, but is independent of metabolic changes.

Regulation of osteogenic differentiation by DNA methylation of the dishevelled gene in bone marrow mesenchymal stem cells

Bone marrow mesenchymal stem cells (BMSCs) are stem cells with multidirectional differentiation potential, which can be used as seed cells to repair and reconstruct many types of tissues and organs following injury or disease. Osteogenic differentiation involves a variety of pathway and factors, including cytokines, growth factors, and hormones. In the present study, we investigated the potential role of Dishevelled in osteogenic differentiation of BMSCs in induction medium containing the methyltransferase inhibitor 5-aza-2'-deoxycytidine. The expression of Dishevelled was analyzed using the reverse transcriptase-polymerase chain reaction (RT-PCR) and a Western blot. The methylation degree of the CpG island in the promoter region of the Dishevelled gene was analyzed, and protein expression levels of Wnt, Glycogen synthase kinase-3 (GSK3), axin, Dishevelled, and β-catenin were increased after the addition of the methyltransferase inhibitor. The expression of Dishevelled increased in accordance with the differentiation of osteoblasts, and the degree of methylation of the promoter affected its expression level. In conclusion, regulating the methylation degree of the Dishevelled gene promoter region appears to influence the expression of Dishevelled and therefore the osteogenic differentiation of BMSCs.

Bone regeneration in minipigs by intrafibrillarly-mineralized collagen loaded with autologous periodontal ligament stem cells

Biomimetic intrafibrillarly-mineralized collagen (IMC) is a promising scaffold for bone regeneration because of its structural and functional similarity to natural bone. The objective of this study was to evaluate the bone regeneration potential of IMC loaded with autologous periodontal ligament stem cells (PDLSCs) in large bone defects in minipigs. A macroporous IMC with a bone-like subfibrillar nanostructure was fabricated using a biomimetic bottom-up approach. Non-healing full thickness defects were established on the cranial bone in minipigs, and IMC and hydroxyapatite (HA) scaffolds seeded with autologous PDLSCs were implanted into these defects. Computed tomographic imaging, histology staining, and atomic force microscopy were applied to evaluate to the quantity, micro/nano structures, and mechanical performance of the neo-bone after 12 weeks of implantation. Compared with HA, IMC showed superior regeneration properties characterized by the profuse deposition of new bony structures with a normal architecture and vascularization. Immunohistochemistry showed that the runt-related transcription factor 2 and transcription factor Osterix were highly expressed in the neo-bone formed by IMC. Furthermore, the nanostructure and nanomechanics of the neo-bone formed by IMC were similar to that of natural bone. This study provides strong evidence for the future clinical applications of the IMC-based bone grafts.

Self-assembled N-cadherin mimetic peptide hydrogels promote the chondrogenesis of mesenchymal stem cells through inhibition of canonical Wnt/β-catenin signaling

N-cadherin, a transmembrane protein and major component of adherens junction, mediates cell-cell interactions and intracellular signaling that are important to the regulation of cell behaviors and organ development. Previous studies have identified mimetic peptides that possess similar bioactivity as that of N-cadherin, which promotes chondrogenesis of human mesenchymal stem cells (hMSCs); however, the molecular mechanism remains unknown. In this study, we combined the N-cadherin mimetic peptide (HAVDI) with the self-assembling KLD-12 peptide: the resultant peptide is capable of self-assembling into hydrogels functionalized with N-cadherin peptide in phosphate-buffered saline (PBS) at 37 °C. Encapsulation of hMSCs in these hydrogels showed enhanced expression of chondrogenic marker genes and deposition of cartilage specific extracellular matrix rich in proteoglycan and Type II Collagen compared to control hydrogels, with a scrambled-sequence peptide after 14 days of chondrogenic culture. Furthermore, western blot showed a significantly higher expression of active glycogen synthase kinase-3β (GSK-3β), which phosphorylates β-catenin and facilitates ubiquitin-mediated degradation, as well as a lower expression of β-catenin and LEF1 in the N-cadherin peptide hydrogels versus controls. Immunofluorescence staining revealed significantly less nuclear localization of β-catenin in N-cadherin mimetic peptide hydrogels. Our findings suggest that N-cadherin peptide hydrogels suppress canonical Wnt signaling in hMSCs by reducing β-catenin nuclear translocation and the associated transcriptional activity of β-catenin/LEF-1/TCF complex, thereby enhancing the chondrogenesis of hMSCs. Our biomimetic self-assembled peptide hydrogels can serve as a tailorable and versatile three-dimensional culture platform to investigate the effect of biofunctionalization on stem cell behavior.

Transdifferentiation of myoblasts into osteoblasts – possible use for bone therapy

Objectives

Transdifferentiation is defined as the conversion of one cell type to another and is an ever-expanding field with a growing number of cells found to be capable of such a process. To date, the fact remains that there are limited treatment options for fracture healing, osteoporosis and bone repair post-destruction by bone tumours. Hence, this review focuses on the transdifferentiation of myoblast to osteoblast as a means to further understand the transdifferentiation process and to investigate a potential therapeutic option if successful.

Key findings

The potent osteoinductive effects of the bone morphogenetic protein-2 are largely implicated in the transdifferentiation of myoblast to osteoblast. Bone morphogenetic protein-2-induced activation of the Smad1 protein ultimately results in JunB synthesis, the first transcriptional step in myoblast dedifferentiation. The upregulation of the activating protein-1 binding activity triggers the transcription of the runt-related transcription factor 2 gene, a transcription factor that plays a major role in osteoblast differentiation.

Summary

This potential transdifferentiation treatment may be utilised for dental implants, fracture healing, osteoporosis and bone repair post-destruction by bone tumours.

Mesenchymal stroma: Role in osteosarcoma progression

The initiation and progression of malignant tumors are supported by their microenvironment: cancer cells per se cannot explain growth and formation of the primary or metastasis, and a combination of proliferating tumor cells, cancer stem cells, immune cells mesenchymal stromal cells and/or cancer-associated fibroblasts all contribute to the tumor bulk. The interaction between these multiple players, under different microenvironmental conditions of biochemical and physical stimuli (i.e. oxygen tension, pH, matrix mechanics), regulates the production and biological activity of several soluble factors, extracellular matrix components, and extracellular vesicles that are needed for growth, maintenance, chemoresistance and metastatization of cancer. In osteosarcoma, a very aggressive cancer of young adults characterized by the extensive need for more effective therapies, this aspect has been only recently explored. In this view, we will discuss the role of stroma, with a particular focus on the mesenchymal stroma, contributing to osteosarcoma progression through inherent features for homing, neovascularization, paracrine cross-feeding, microvesicle secretion, and immune modulation, and also by responding to the changes of the microenvironment that are induced by tumor cells. The most recent advances in the molecular cues triggered by cytokines, soluble factors, and metabolites that are partially beginning to unravel the axis between stromal elements of mesenchymal origin and osteosarcoma cells, will be reviewed providing insights likely to be used for novel therapeutic approaches against sarcomas.