MSC Transplantation Improves Osteopenia via Epigenetic Regulation of Notch Signaling in Lupus

Extracellular vesicles as modifiers of epigenomic profiles

Extracellular vesicles (EVs), emerging as novel mediators between intercellular communication, encapsulate distinct bioactive cargoes to modulate multiple biological events, such as epigenetic remodeling. In essence, EVs and epigenomic profiles are tightly linked and reciprocally regulated. Epigenetic factors, including histone and DNA modifications, noncoding RNAs, and protein post-translational modifications (PTMs) dynamically regulate EV biogenesis to contribute to EV heterogeneity. Alternatively, EVs actively modify DNA, RNA, and histone profiles in recipient cells by delivering RNA and protein cargoes for downstream epigenetic enzyme regulation. Moreover, EVs display great potential as diagnostic markers and drug-delivery vehicles for therapeutic applications. The combination of parental cell epigenomic modification with single EV characterization would be a promising strategy for EV engineering to enhance the epidrug loading efficacy and accuracy.

Effect of DNA methylation on the osteogenic differentiation of mesenchymal stem cells: concise review

Mesenchymal stem cells (MSCs) have promising potential for bone tissue engineering in bone healing and regeneration. They are regarded as such due to their capacity for self-renewal, multiple differentiation, and their ability to modulate the immune response. However, changes in the molecular pathways and transcription factors of MSCs in osteogenesis can lead to bone defects and metabolic bone diseases. DNA methylation is an epigenetic process that plays an important role in the osteogenic differentiation of MSCs by regulating gene expression. An increasing number of studies have demonstrated the significance of DNA methyltransferases (DNMTs), Ten-eleven translocation family proteins (TETs), and MSCs signaling pathways about osteogenic differentiation in MSCs. This review focuses on the progress of research in these areas.

The potential role of stem cells-derived extracellular vesicles in the treatment of musculoskeletal system diseases

The therapeutic potential of stem cells-derived extracellular vesicles (EVs) has shown a great progress in the regenerative medicine. EVs are rich in a variety of bioactive substances, which are important carriers of signal transmission and interactions between cells, and they play an important role in the processes of tissue repair and regeneration. Several studies have shown that stem cells-derived EVs regulate immunity, promote cell proliferation and differentiation, enhance bone and vascular regeneration, and play an increasingly important role in musculoskeletal system. This review aimed to describe the biological characteristics of stem cells-derived EVs and discuss their potential role in the therapy of musculoskeletal system diseases.

Autonomic neural regulation in mediating the brain-bone axis: mechanisms and implications for regeneration under psychological stress

Efficient regeneration of bone defects caused by disease or significant trauma is a major challenge in current medicine, which is particularly difficult yet significant under the emerging psychological stress in the modern society. Notably, the brain-bone axis has been proposed as a prominent new concept in recent years, among which autonomic nerves act as an essential and emerging skeletal pathophysiological factor related to psychological stress. Studies have established that sympathetic cues lead to impairment of bone homeostasis mainly through acting on mesenchymal stem cells (MSCs) and their derivatives with also affecting the hematopoietic stem cell (HSC)-lineage osteoclasts, and the autonomic neural regulation of stem cell lineages in bone is increasingly recognized to contribute to the bone degenerative disease, osteoporosis. This review summarizes the distribution characteristics of autonomic nerves in bone, introduces the regulatory effects and mechanisms of autonomic nerves on MSC and HSC lineages, and expounds the crucial role of autonomic neural regulation on bone physiology and pathology, which acts as a bridge between the brain and the bone. With the translational perspective, we further highlight the autonomic neural basis of psychological stress-induced bone loss and a series of pharmaceutical therapeutic strategies and implications toward bone regeneration. The summary of research progress in this field will add knowledge to the current landscape of inter-organ crosstalk and provide a medicinal basis for the achievement of clinical bone regeneration in the future.

Understanding exosomes: Part 2-Emerging leaders in regenerative medicine

Exosomes are the smallest subset of extracellular signaling vesicles secreted by most cells with the ability to communicate with other tissues and cell types over long distances. Their use in regenerative medicine has gained tremendous momentum recently due to their ability to be utilized as therapeutic options for a wide array of diseases/conditions. Over 5000 publications are currently being published yearly on this topic, and this number is only expected to dramatically increase as novel therapeutic strategies continue to be developed. Today exosomes have been applied in numerous contexts including neurodegenerative disorders (Alzheimer's disease, central nervous system, depression, multiple sclerosis, Parkinson's disease, post-traumatic stress disorders, traumatic brain injury, peripheral nerve injury), damaged organs (heart, kidney, liver, stroke, myocardial infarctions, myocardial infarctions, ovaries), degenerative processes (atherosclerosis, diabetes, hematology disorders, musculoskeletal degeneration, osteoradionecrosis, respiratory disease), infectious diseases (COVID-19, hepatitis), regenerative procedures (antiaging, bone regeneration, cartilage/joint regeneration, osteoarthritis, cutaneous wounds, dental regeneration, dermatology/skin regeneration, erectile dysfunction, hair regrowth, intervertebral disc repair, spinal cord injury, vascular regeneration), and cancer therapy (breast, colorectal, gastric cancer and osteosarcomas), immune function (allergy, autoimmune disorders, immune regulation, inflammatory diseases, lupus, rheumatoid arthritis). This scoping review is a first of its kind aimed at summarizing the extensive regenerative potential of exosomes over a broad range of diseases and disorders.

FGF2/HGF priming facilitates adipose-derived stem cell-mediated bone formation in osteoporotic defects

Aims

The activity of adipose-derived stem cells (ADSCs) is susceptible to the physiological conditions of the donor. Therefore, employing ADSCs from donors of advanced age or with diseases for cell therapy necessitates a strategy to enhance therapeutic efficacy before transplantation. This study aims to investigate the impact of supplementing Fibroblast Growth Factor 2 (FGF2) and Hepatocyte Growth Factor (HGF) on ADSC-mediated osteogenesis under osteoporotic conditions and to explore the underlying mechanisms of action.

Main methods

Adipose-derived stem cells (ADSCs) obtained from ovariectomized (OVX) rats were cultured ex vivo. These cells were cultured in an osteogenic medium supplemented with FGF2 and HGF and subsequently autologously transplanted into osteoporotic femur defects using Hydroxyapatite-Tricalcium Phosphate. The assessment of bone formation was conducted four weeks post-transplantation.

Key findings

Osteoporosis detrimentally affects the viability and osteogenic differentiation potential of ADSCs, often accompanied by a deficiency in FGF2 and HGF signaling. However, priming with FGF2 and HGF facilitated the formation of immature osteoblasts from OVX ADSCs in vitro, promoting the expression of osteoblastogenic proteins, including Runx-2, osterix, and ALP, during the early phase of osteogenesis. Furthermore, FGF2/HGF priming augmented the levels of VEGF and SDF-1α in the microenvironment of OVX ADSCs under osteogenic induction. Importantly, transplantation of OVX ADSCs primed with FGF2/HGF for 6 days significantly enhanced bone formation compared to non-primed cells. The success of bone regeneration was confirmed by the expression of type-1 collagen and osteocalcin in the bone tissue of the deficient area.

Significance

Our findings corroborate that priming with FGF2/HGF can improve the differentiation potential of ADSCs. This could be applied in autologous stem cell therapy for skeletal disease in the geriatric population.

Design, Synthesis, and Anti-Osteoporotic Characterization of Arginine N-Glycosylated Teriparatide Analogs via the Silver-catalyzed Solid-Phase Glycosylation Strategy

In spite of effective antiosteoporosis potency, teriparatide, a bone-building agent approved by the FDA (Food and Drug Administration), was proven to exhibit various side effects. In our previous work, we developed a universal strategy for synthesizing arginine N-glycosylated peptides termed silver-promoted solid-phase glycosylation (SSG) strategy. However, it is unknown whether the SSG strategy can be applied in the peptide drug design. Herein, we first reported the optimization of teriparatide via SSG strategy. Using Arg20 and/or Arg25 as the modifying positions, three series of arginine N-glycosylated teriparatide analogs were successfully synthesized, of which the introduced sugar groups included glucose, galactose, mannose, rhamnose, ribose, 2-acetamino-2-deoxy-glucose, xylose, lactose, and maltose. Among the 27 arginine N-glycosylated derivatives, Arg20-xylose and Arg25-maltose teriparatide analogs, termed PTH-1g and PTH-2i, respectively, indicated enhanced serum stability and significantly improved antiosteoporotic activities in vitro and in vivo compared with the native counterpart. They may serve as effective therapeutic candidates for treating osteoporosis.

Preparation of genetically or chemically engineered exosomes and their therapeutic effects in bone regeneration and anti-inflammation

The treatment of bone or cartilage damage and inflammation-related diseases has been a long-standing research hotspot. Traditional treatments such as surgery and cell therapy have only displayed limited efficacy because they can't avoid potential deterioration and ensure cell activity. Recently, exosomes have become a favorable tool for various tissue reconstruction due to their abundant content of proteins, lipids, DNA, RNA and other substances, which can promote bone regeneration through osteogenesis, angiogenesis and inflammation modulation. Besides, exosomes are also promising delivery systems because of stability in the bloodstream, immune stealth capacity, intrinsic cell-targeting property and outstanding intracellular communication. Despite having great potential in therapeutic delivery, exosomes still show some limitations in clinical studies, such as inefficient targeting ability, low yield and unsatisfactory therapeutic effects. In order to overcome the shortcomings, increasing studies have prepared genetically or chemically engineered exosomes to improve their properties. This review focuses on different methods of preparing genetically or chemically engineered exosomes and the therapeutic effects of engineering exosomes in bone regeneration and anti-inflammation, thereby providing some references for future applications of engineering exosomes.

Wen-Shen-Tong-Luo-Zhi-Tong Decoction regulates bone-fat balance in osteoporosis by adipocyte-derived exosomes

CONTEXT

Wen-Shen-Tong-Luo-Zhi-Tong (WSTLZT) Decoction is a Chinese prescription with antiosteoporosis effects, especially in patients with abnormal lipid metabolism.

OBJECTIVE

To explore the effect and mechanism of WSTLZT on osteoporosis (OP) through adipocyte-derived exosomes.

MATERIALS AND METHODS

Adipocyte-derived exosomes with or without WSTLZT treated were identified by transmission electron microscopy, nanoparticle tracking analysis (NTA) and western blotting (WB). Co-culture experiments for bone marrow mesenchymal stem cells (BMSCs) and exosomes were performed to examine the uptake and effect of exosome in osteogenesis and adipogenic differentiation of BMSC. MicroRNA profiles, luciferase and IP were used for exploring specific mechanisms of exosome on BMSC. In vivo, 80 Balb/c mice were randomly divided into four groups: Sham, Ovx, Exo (30 μg exosomes), Exo-WSTLZT (30 μg WSTLZT-exosomes), tail vein injection every week. After 12 weeks, the bone microstructure and marrow fat distribution were analysed by micro-CT.

RESULTS

ALP, Alizarin red and Oil red staining showed that WSTLZT-induced exosomes from adipocyte can regulate osteoblastic and adipogenic differentiation of BMSC. MicroRNA profiles observed that WSTLZT treatment resulted in 87 differentially expressed miRNAs (p < 0.05). MiR-122-5p with the greatest difference was screened by q-PCR (p < 0.01). The target relationship between miR-122-5p and SPRY2 was tested by luciferase and IP. MiR-122-5p negatively regulated SPRY2 and elevated the activity of MAPK signalling pathway, thereby regulating the osteoblastic and adipogenic differentiation of BMSC. In vivo, exosomes can not only improve bone microarchitecture but also significantly reduce accumulation of bone marrow adipose.

CONCLUSIONS

WSTLZT can exert anti-OP effect through SPRY2 via the MAKP signalling by miR-122-5p carried by adipocyte-derived exosomes.

Circulating miR-320b Contributes to CD4+ T-Cell Proliferation in Systemic Lupus Erythematosus via MAP3K1

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of autoantibodies and tissue inflammation. Mesenchymal stem cells (MSCs) have emerged as a promising candidate therapy for SLE owing to the immunomodulatory and regenerative properties. Circulating miRNAs are small, single-stranded noncoding RNAs in a variety of body fluids that regulate numerous immunologic and inflammatory pathways. Recent studies have revealed many differentially expressed circulating miRNAs in autoimmune diseases including SLE. However, the role of circulating miRNAs in SLE has not been extensively studied. Here, we performed small RNA sequencing analysis to compare the circulating miRNA profiles of SLE patients before and after MSC transplantation (MSCT), and identified a significant decrease of circulating miR-320b level during MSCT. Importantly, we found that the expression of circulating miR-320b and its target gene MAP3K1 was closely associated with SLE disease activity. The in vitro experiments showed that decreased MAP3K1 level in SLE peripheral blood mononuclear cells (PBMCs) was involved in CD4+ T-cell proliferation. In MRL/lpr mice, miR-320b overexpression aggravated symptoms of SLE, while miR-320b inhibition could promote disease remission. Besides, MSCs regulate miR-320b/MAP3K1 expression both in vitro and in vivo. Our results suggested that circulating miR-320b and MAP3K1 may be involved in CD4+ T-cell proliferation in SLE. This trial is registered with NCT01741857.

CK1ε drives osteogenic differentiation of bone marrow mesenchymal stem cells via activating Wnt/β-catenin pathway

The treatment of bone defects is a difficult problem in orthopedics. At present, the treatment mainly relies on autologous or allogeneic bone transplantation, which may lead to some complications such as foreign body rejection, local infection, pain, or numbness at the bone donor site. Local injection of conservative therapy to treat bone defects is one of the research hotspots at present. Bone marrow mesenchymal stem cells (BMSCs) can self-renew, significantly proliferate, and differentiate into various types of cells. Although it has been reported that CK1ε could mediate the Wnt/β-catenin pathway, leading to the development of the diseases, whether CK1ε plays a role in bone regeneration through the Wnt/β-catenin pathway has rarely been reported. The purpose of this study was to investigate whether CK1ε was involved in the osteogenic differentiation (OD) of BMSCs through the Wnt/β-catenin pathway and explore the mechanism. We used quantitative reverse transcription-polymerase chain reaction (qRT-qPCR), Western blots, immunofluorescence, alkaline phosphatase, and alizarin red staining to detect the effect of CK1ε on the OD of BMSCs and the Wnt/β-catenin signaling pathway. CK1ε was highly expressed in BMSCs with OD, and our study further demonstrated that CK1ε might promote the OD of BMSCs by activating DLV2 phosphorylation, initiating Wnt signaling downstream, and activating β-catenin nuclear transfer. In addition, by locally injecting a CK1ε-carrying adeno-associated virus (AAV5- CK1ε) into a femoral condyle defect rat model, the overexpression of CK1ε significantly promoted bone repair. Our data show that CK1ε was involved in the regulation of OD by mediating Wnt/β-catenin. This may provide a new strategy for the treatment of bone defects.

Research progress of extracellular vesicles and exosomes derived from mesenchymal stem cells in the treatment of oxidative stress-related diseases

There is growing evidence that mesenchymal stem cell-derived extracellular vesicles and exosomes can significantly improve the curative effect of oxidative stress-related diseases. Mesenchymal stem cell extracellular vesicles and exosomes (MSC-EVs and MSC-Exos) are rich in bioactive molecules and have many biological regulatory functions. In this review, we describe how MSC-EVs and MSC-Exos reduce the related markers of oxidative stress and inflammation in various systemic diseases, and the molecular mechanism of MSC-EVs and MSC-Exos in treating apoptosis and vascular injury induced by oxidative stress. The results of a large number of experimental studies have shown that both local and systemic administration can effectively inhibit the oxidative stress response in diseases and promote the survival and regeneration of damaged parenchymal cells. The mRNA and miRNAs in MSC-EVs and MSC-Exos are the most important bioactive molecules in disease treatment, which can inhibit the apoptosis, necrosis and oxidative stress of lung, heart, kidney, liver, bone, skin and other cells, and promote their survive and regenerate.

Mesenchymal condensation in tooth development and regeneration: a focus on translational aspects of organogenesis

The teeth are vertebrate-specific, highly specialized organs performing fundamental functions of mastication and speech, the maintenance of which is crucial for orofacial homeostasis and is further linked to systemic health and human psychosocial well-being. However, with limited ability for self-repair, the teeth can often be impaired by traumatic, inflammatory, and progressive insults, leading to high prevalence of tooth loss and defects worldwide. Regenerative medicine holds the promise to achieve physiological restoration of lost or damaged organs, and in particular an evolving framework of developmental engineering has pioneered functional tooth regeneration by harnessing the odontogenic program. As a key event of tooth morphogenesis, mesenchymal condensation dictates dental tissue formation and patterning through cellular self-organization and signaling interaction with the epithelium, which provides a representative to decipher organogenetic mechanisms and can be leveraged for regenerative purposes. In this review, we summarize how mesenchymal condensation spatiotemporally assembles from dental stem cells (DSCs) and sequentially mediates tooth development. We highlight condensation-mimetic engineering efforts and mechanisms based on ex vivo aggregation of DSCs, which have achieved functionally robust and physiologically relevant tooth regeneration after implantation in animals and in humans. The discussion of this aspect will add to the knowledge of development-inspired tissue engineering strategies and will offer benefits to propel clinical organ regeneration.

The role of mesenchymal stem cell-derived exosome in epigenetic modifications in inflammatory diseases

Epigenetic modification is a complex process of reversible and heritable alterations in gene function, and the combination of epigenetic and metabolic alterations is recognized as an important causative factor in diseases such as inflammatory bowel disease (IBD), osteoarthritis (OA), systemic lupus erythematosus (SLE), and even tumors. Mesenchymal stem cell (MSC) and MSC-derived exosome (MSC-EXO) are widely studied in the treatment of inflammatory diseases, where they appear to be promising therapeutic agents, partly through the potent regulation of epigenetic modifications such as DNA methylation, acetylation, phosphorylation, and expression of regulatory non-coding RNAs, which affects the occurrence and development of inflammatory diseases. In this review, we summarize the current research on the role of MSC-EXO in inflammatory diseases through their modulation of epigenetic modifications and discuss its potential application in the treatment of inflammatory diseases.

Osteoporosis treatment using stem cell-derived exosomes: a systematic review and meta-analysis of preclinical studies

BACKGROUND

The increasing incidence of osteoporosis in recent years has aroused widespread public concern; however, existing effective treatments are limited. Therefore, new osteoporosis treatment methods, including stem cell transplantation and exosome therapy, have been proposed and are gaining momentum. Exosomes are considered to have greater potential for clinical application owing to their immunocompatibility. This study summarises the latest evidence demonstrating the efficacy of exosomes in improving bone loss in the treatment of osteoporosis.

MAIN TEXT

This systematic review and meta-analyses searched PubMed, Embase, and Cochrane Library databases from inception to 26 March 2022 for osteoporosis treatment studies using stem cell-derived exosomes. Six endpoints were selected to determine efficacy: bone mineral density, trabecular bone volume/tissue volume fraction, trabecular number, trabecular separation, trabecular thickness, and cortical thickness. The search generated 366 citations. Eventually, 11 articles that included 15 controlled preclinical trials and 242 experimental animals (rats and mice) were included in the meta-analysis.

CONCLUSION

The results were relatively robust and reliable despite some publication biases, suggesting that exosome treatment increased bone mass, improved bone microarchitecture, and enhanced bone strength compared with placebo treatments. Moreover, stem cell-derived exosomes may favour anabolism over catabolism, shifting the dynamic balance towards bone regeneration.

Mesenchymal stem cells: Emerging concepts and recent advances in their roles in organismal homeostasis and therapy

Stem cells play a crucial role in re-establishing homeostasis in the body, and the search for mechanisms by which they interact with the host to exert their therapeutic effects remains a key question currently being addressed. Considering their significant regenerative/therapeutic potential, research on mesenchymal stem cells (MSCs) has experienced an unprecedented advance in recent years, becoming the focus of extensive works worldwide to develop cell-based approaches for a variety of diseases. Initial evidence for the effectiveness of MSCs therapy comes from the restoration of dynamic microenvironmental homeostasis and endogenous stem cell function in recipient tissues by systemically delivered MSCs. The specific mechanisms by which the effects are exerted remain to be investigated in depth. Importantly, the profound cell-host interplay leaves persistent therapeutic benefits that remain detectable long after the disappearance of transplanted MSCs. In this review, we summarize recent advances on the role of MSCs in multiple disease models, provide insights into the mechanisms by which MSCs interact with endogenous stem cells to exert therapeutic effects, and refine the interconnections between MSCs and cells fused to damaged sites or differentiated into functional cells early in therapy.

Application of the neuropeptide NPVF to enhance angiogenesis and osteogenesis in bone regeneration

The brain-bone regulatory system regulates skeletal homeostasis via bioactive neuropeptides, yet the underlying mechanism remains elusive. Here, we report the role of the neuropeptide VF (NPVF, VPNLPQRF-NH2) in enhancing both angiogenesis and osteogenesis in a rat skeletal system and the potential pathways involved. An in vitro study revealed that NPVF not only promotes migration and angiogenesis of human umbilical vein endothelial cells (HUVECs) by activating NPFFR1, which leads to upregulation of miR-181c-3p and downregulation of Argonaute1 (AGO1), but also mediates osteogenic differentiation of bone mesenchymal stem cells (BMSCs) via the Wnt/β-catenin signaling pathway. To improve the stability and bioavailability and thus efficacy of NPVF as a promoter of in vivo bone regeneration, we genetically engineered amyloid-NPVF-fusion proteins and utilized them as self-assembling nanofiber coatings to treat bone defects in a rat calvarial defect model. We found that a porous hydroxyapatite scaffold loaded with the NPVF peptide-fused amyloid coating substantially enhanced angiogenesis and site-specific fresh bone in-growth when implanted in calvarial defects. Taken together, our work uncovered a previously undefined crosstalk between the brain and bone by unveiling the role of NPVF in bone tissue and demonstrated a viable method for promoting bone tissue repairs based upon self-assembling NPVF-containing protein coatings.

Bone Metastasis Initiation Is Coupled with Bone Remodeling through Osteogenic Differentiation of NG2+ Cells

The bone microenvironment is dynamic and undergoes remodeling in normal and pathologic conditions. Whether such remodeling affects disseminated tumor cells (DTC) and bone metastasis remains poorly understood. Here, we demonstrated that pathologic fractures increase metastatic colonization around the injury. NG2+ cells are a common participant in bone metastasis initiation and bone remodeling in both homeostatic and fractured conditions. NG2+ bone mesenchymal stem/stromal cells (BMSC) often colocalize with DTCs in the perivascular niche. Both DTCs and NG2+ BMSCs are recruited to remodeling sites. Ablation of NG2+ lineage impaired bone remodeling and concurrently diminished metastatic colonization. In cocultures, NG2+ BMSCs, especially when undergoing osteodifferentiation, enhanced cancer cell proliferation and migration. Knockout of N-cadherin in NG2+ cells abolished these effects in vitro and phenocopied NG2+ lineage depletion in vivo. These findings uncover dual roles of NG2+ cells in metastasis and remodeling and indicate that osteodifferentiation of BMSCs promotes metastasis initiation via N-cadherin-mediated cell-cell interaction.

SIGNIFICANCE

The bone colonization of cancer cells occurs in an environment that undergoes constant remodeling. Our study provides mechanistic insights into how bone homeostasis and pathologic repair lead to the outgrowth of disseminated cancer cells, thereby opening new directions for further etiologic and epidemiologic studies of tumor recurrences. This article is highlighted in the In This Issue feature, p. 247.

microRNA-29b-3p/sirtuin-1/peroxisome proliferator-activated receptor γ suppress osteogenic differentiation

Osteoporosis is described as an age-associated impairment of bone formation. microRNA (miR)-29b-3p was thought to be linked to osteoblast differentiation; however, the underlying molecular pathways are yet unknown. The study's goal was to look into the involvement of miR-29b-3p in osteoporosis and the pathophysiological mechanisms. A murine model of estrogen deficiency-induced bone loss was established to simulate postmenopausal osteoporosis. Reverse transcription-quantitative PCR (RT-qPCR) was performed to assess the level of miR-29b-3p of bone tissue. Additionally, miR-29b-3p/sirtuin-1 (SIRT1)/peroxisome proliferator-activated receptor γ (PPARγ) axis in the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) was examined. Osteogenesis-related markers, including alkaline phosphatase (ALP), osteocalcin (OCN), and runt-related transcription factor 2 (RUNX2), were assessed at protein and molecular levels. ALP staining and Alizarin Red staining were used to detect ALP activity and calcium deposition. The ovariectomy group was shown to express miR-29b-3p at higher levels in vitro, and miR-29b-3p mimics suppressed osteogenic differentiation and protein/mRNA expression levels of osteogenesis-related markers in vivo. SIRT1 was identified as a target of miR-29b-3p using luciferase reporter assays. Overexpression of SIRT1 reduced the inhibition of osteogenic differentiation by miR-29b-3p. Rosiglitazone, an activator of PPARγ signaling, was able to reverse the downregulation of the osteogenic differentiation of BMSCs and the protein expression of PPARγ caused by miR-29b-3p inhibitors. The results revealed that osteogenesis was suppressed by miR-29b-3p, which blocks the SIRT1/PPARγ axis. These results suggested that postmenopausal osteoporosis could be treated by targeting miR-29b-3p SIRT1/PPARγ.

Current Progress in Treating Systemic Lupus Erythematosus Using Exosomes/MicroRNAs

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease associated with impaired organ functions that can seriously affect the daily life of patients. Recent SLE therapies frequently elicit adverse reactions and side effects in patients, and clinical heterogeneity is considerable. Mesenchymal stromal cells (MSCs) have anti-inflammatory, tissue repair, and immunomodulatory properties. Their ability to treat autoimmune diseases largely depends on secreted extracellular vesicles, especially exosomes. The effects of exosomes and microRNAs (miRNAs) on SLE have recently attracted interest. This review summarizes the applications of MSCs derived from bone marrow, adipocyte tissue, umbilical cord, synovial membrane, and gingival tissue, as well as exosomes to treating SLE and the key roles of miRNAs. The efficacy of MSCs infusion in SLE patients with impaired autologous MSCs are reviewed, and the potential of exosomes and their contents as drug delivery vectors for treating SLE and other autoimmune diseases in the future are briefly described.

Clinical experience: Outcomes of mesenchymal stem cell transplantation in five stroke patients

Stem cell therapy, which has promising results in acute disorders such as stroke, supports treatment by providing rehabilitation in the chronic stage patients. In acute stroke, thrombolytic medical treatment protocols are clearly defined in neurologic emergencies, but in neurologic patients who miss the "thrombolytic treatment intervention window," or in cases of hypoxic-ischemic encephalopathy, our hands are tied, and we are still unfortunately faced with hopeless clinical implementations. We consider mesenchymal stem cell therapy a viable option in these cases. In recent years, novel research has focused on neuro-stimulants and supportive and combined therapies for stroke. Currently, available treatment options are limited, and only certain patients are eligible for acute treatment. In the scope of our experience, five stroke patients were evaluated in this study, who was treated with a single dose of 1-2 × 10⁶ cells/kg allogenic umbilical cord-mesenchymal stem cells (UC-MSCs) with the official confirmation of the Turkish Ministry of Health Stem Cell Commission. The patients were followed up for 12 months, and clinical outcomes are recorded. NIH Stroke Scale/Scores (NIHSS) decreased significantly (p = 0.0310), and the Rivermead Assessment Scale (RMA) increased significantly (p = 0.0234) for all patients at the end of the follow-up. All the patients were followed up for 1 year within a rehabilitation program. Major clinical outcome improvements were observed in the overall clinical conditions of the UC-MSC treatment patients. We observed improvement in the patients' upper extremity and muscle strength, spasticity, and fine motor functions. Considering recent studies in the literature together with our results, allogenic stem cell therapies are introduced as promising novel therapies in terms of their encouraging effects on physiological motor outcomes.

Extracellular Vesicles for Dental Pulp and Periodontal Regeneration

Extracellular vesicles (EVs) are lipid bound particles derived from their original cells, which play critical roles in intercellular communication through their cargoes, including protein, lipids, and nucleic acids. According to their biogenesis and release pathway, EVs can be divided into three categories: apoptotic vesicles (ApoVs), microvesicles (MVs), and small EVs (sEVs). Recently, the role of EVs in oral disease has received close attention. In this review, the main characteristics of EVs are described, including their classification, biogenesis, biomarkers, and components. Moreover, the therapeutic mechanism of EVs in tissue regeneration is discussed. We further summarize the current status of EVs in pulp/periodontal tissue regeneration and discuss the potential mechanisms. The therapeutic potential of EVs in pulp and periodontal regeneration might involve the promotion of tissue regeneration and immunomodulatory capabilities. Furthermore, we highlight the current challenges in the translational use of EVs. This review would provide valuable insights into the potential therapeutic strategies of EVs in dental pulp and periodontal regeneration.

Notch1 signalling controls the differentiation and function of myeloid-derived suppressor cells in systemic lupus erythematosus

Emerging studies have reported the expansion of myeloid-derived suppressor cells (MDSCs) in some autoimmune disorders, such as systemic lupus erythematosus (SLE), but the detailed molecular mechanisms of the aberrant expansion in SLE are still unclear. In the present study, we confirmed that the increased MDSCs positively correlated with disease activity in SLE patients. The suppressive capacity of MDSCs from patients with high activity was lower than that of MDSCs from patients with low activity. Moreover, the potential precursors for MDSCs, common myeloid progenitors (CMPs) and granulocyte-monocyte progenitors (GMPs), were markedly increased in the bone marrow (BM) aspirates of SLE patients. As an important regulator of cell fate decisions, aberrant activation of Notch signalling was reported to participate in the pathogenesis of SLE. We found that the expression of Notch1 and its downstream target gene hairy and enhancer of split 1 (Hes-1) increased markedly in GMPs from SLE patients. Moreover, the Notch1 signalling inhibitor DAPT profoundly relieved disease progression and decreased the proportion of MDSCs in pristane-induced lupus mice. The frequency of GMPs was also decreased significantly in lupus mice after DAPT treatment. Furthermore, the inhibition of Notch1 signalling could limit the differentiation of MDSCs in vitro. The therapeutic effect of DAPT was also verified in Toll-like receptor 7 (TLR7) agonist-induced lupus mice. Taken together, our results demonstrated that Notch1 signalling played a crucial role in MDSC differentiation in SLE. These findings will provide a promising therapy for the treatment of SLE.

Extracellular vesicles rejuvenate the microenvironmental modulating function of recipient tissue-specific mesenchymal stem cells in osteopenia treatment

Systemic transplantation of mesenchymal stem cells (MSCs), such as bone marrow MSCs (BMMSCs) and stem cells from human exfoliated deciduous teeth (SHED), is considered a prominent treatment for osteopenia. However, the mechanism of action of the transplanted MSCs has been poorly elucidated. In the recipient target tissue, including bone and bone marrow, only a few donor MSCs can be detected, suggesting that the direct contribution of donor MSCs may not be expected for osteopenia treatment. Meanwhile, secretomes, especially contents within extracellular vesicles (EVs) released from donor MSCs (MSC-EVs), play key roles in the treatment of several diseases. In this context, administrated donor MSC-EVs may affect bone-forming function of recipient cells. In this review, we discuss how MSC-EVs contribute to bone recovery recipient tissue in osteopenia. We also summarize a novel mechanism of action of systemic administration of SHED-derived EVs (SHED-EVs) in osteopenia. We found that reduced telomerase activity in recipient BMMSCs caused the deficiency of microenvironmental modulating function, including bone and bone marrow-like niche formation and immunomodulation in estrogen-deficient osteopenia model mice. Systemic administration of SHED-EVs could exert therapeutic effects on bone reduction via recovering the telomerase activity, leading to the rejuvenation of the microenvironmental modulating function in recipient BMMSCs, as seen in systemic transplantation of SHED. RNase-preconditioned donor SHED-EVs diminished the therapeutic benefits of administrated SHED-EVs in the recipient osteopenia model mice. These facts suggest that MSC-EV therapy targets the recipient BMMSCs to rejuvenate the microenvironmental modulating function via telomerase activity, recovering bone density. We then introduce future challenges to develop the reproducible MSC-EV therapy in osteopenia.

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.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: The Novel Therapeutic Option for Regenerative Dentistry

Dental mesenchymal stem cells (MSCs) are characterized by unlimited self-renewal ability and high multidirectional differentiation potential. Since dental MSCs can be easily isolated and exhibit a high capability to differentiate into odontogenic cells, they are considered as attractive therapeutic agents in regenerative dentistry. Recently, MSC-derived extracellular vesicles (MSC-EVs) have attracted widespread attention as carriers for cell-free therapy due to their potential functions. Many studies have shown that MSC-EVs can mediate microenvironment at tissue damage site, and coordinate the regeneration process. Additionally, MSC-EVs can mediate intercellular communication, thus affecting the phenotypes and functions of recipient cells. In this review, we mainly summarized the types of MSCs that could be potentially applied in regenerative dentistry, the possible molecular cargos of MSC-EVs, and the major effects of MSC-EVs on the therapeutic induction of osteogenic differentiation.

The potential therapeutic value and application prospect of engineered exosomes in human diseases

Exosomes are tiny vesicles produced by a wide range of cells that contain complex RNA and protein. In the diagnosis, treatment, and prevention of illness, they offer great potential. In vitro engineering technique modifies exosomes to produce designed exosomes that include nucleic acids, proteins, and medicines, and are targeted to particular tissues or cells. Their applications range from tumor imaging and gene therapy to vaccine production and regenerative medicine to targeted medication delivery. Many disciplines have promising futures for using this technology. In this review, we'll look at the potential therapeutic usefulness and use of engineered exosomes in a variety of human illnesses with various systemic manifestations.

Mesenchymal stem cells and connective tissue diseases: From bench to bedside

The pathogenesis of connective tissue diseases (CTDs), represented by systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc), primary Sjögren’s syndrome (pSS), and idiopathic inflammatory myopathies (IIM), includes various immune cells involved in both innate and adaptive immunity. The mesenchymal stem cells (MSCs) are unique due to their regulatory effect on immunity. This makes them a promising therapeutic approach for patients with immune-mediated disorders such as CTD. The safety and clinical efficacy of MSC treatment in CTD have been tested in a growing number of preclinical and clinical studies. Administration of MSCs has consistently shown benefits with both symptomatic and histologic improvement in CTD animal models. MSC therapies in severe and drug-resistant CTD patients have shown promise in a number of the pilot studies, cohort studies, and randomized controlled trials in SLE, RA, and SSc, but some problems still need to be resolved in the transition from the bench to the bedside. The relevant studies in pSS and IIM are still in their infancy, but have displayed encouraging outcomes. Considerable efficacy variations have been observed in terms of the route of delivery, time of MSC injection, origin of the MSCs and dosage. Furthermore, the optimization of conventional drugs combined with MSC therapies and the applications of novel cell engineering approaches requires additional research. In this review, we summarize the current evidence about the immunoregulatory mechanism of MSCs, as well as the preclinical and clinical studies of MSC-based therapy for the treatment of CTDs.

MiR-100-5p inhibits osteogenic differentiation of human bone mesenchymal stromal cells by targeting TMEM135

Osteoporosis is a disorder characterized by reduced bone mass, disruption of bone microarchitecture, and a propensity to fracture. The osteogenic differentiation of human bone mesenchymal stromal cells (hBMSCs) exerts a critical effect on preventing bone loss during osteoporosis. Herein, the study recognized miR-100-5p as a deregulated miRNA during osteoporosis (upregulated) and BMSC osteogenic differentiation (downregulated). miR-100-5p was upregulated in osteoporosis patients-isolated BMSCs compared to non-osteoporosis trauma patients-isolated BMSCs. hBMSCs, overexpression inhibited hBMSC proliferation and osteogenic differentiation, whereas miR-100-5p inhibition exerted opposite effects. TMEM135 was downregulated in osteoporosis and upregulated in differentiated osteoblasts, as well as downregulated upon the overexpression of miR-100-5p. MiR-100-5p directly targeted and inhibited TMEM135. In hBMSCs, TMEM135 silencing also inhibited hBMSC osteogenic differentiation. When co-transfected to hBMSCs, antagomir-100-5p promoted, whereas TMEM135 silencing inhibited hBMSC osteogenic differentiation; TMEM135 knockdown dramatically attenuated the effects of miR-100-5p inhibition. Taken together, miR-100-5p forms a regulatory axis with TMEM135 by direct binding. The miR-100-5p/TMEM135 axis modulates hBMSC differentiation into osteoblast. Considering the critical effect of BMSC osteogenesis on osteoporosis, this axis might play a role in osteoporosis, and further in vivo and clinical investigations are required.

Exosomes in bone remodeling and breast cancer bone metastasis

Exosomes are endosome-derived microvesicles that carry cell-specific biological cargo, such as proteins, lipids, and noncoding RNAs (ncRNAs). They play a key role in bone remodeling by enabling the maintenance of a balance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption. Recent evidence indicates that exosomes disrupt bone remodeling that occurs during breast cancer (BC) progression. The bone is a preferred site for BC metastasis owing to its abundant osseous reserves. In this review, we aimed to highlight the roles of exosomes derived from bone cells and breast tumor in bone remodeling and BC bone metastasis (BCBM). We also briefly outline the mechanisms of action of ncRNAs and proteins carried by exosomes secreted by bone and BCBM. Furthermore, this review highlights the potential of utilizing exosomes as biomarkers or delivery vehicles for the diagnosis and treatment of BCBM.

Mechanically Robust Hydrogels Facilitating Bone Regeneration through Epigenetic Modulation

Development of artificial biomaterials by mimicking extracellular matrix of bone tissue is a promising strategy for bone regeneration. Hydrogel has emerged as a type of viable substitute, but its inhomogeneous networks and weak mechanics greatly impede clinical applications. Here, a dual crosslinked gelling system is developed with tunable architectures and mechanics to promote osteogenic capacity. Polyhedral oligomeric silsesquioxane (POSS) is designated as a rigid core surrounded by six disulfide-linked PEG shells and two 2-ureido-4[1H]-pyrimidinone (UPy) groups. Thiol-disulfide exchange is employed to fabricate chemical network because of the pH-responsive "on/off" function. While self-complementary UPy motif is capable of optimizing local microstructure to enhance mechanical properties. Taking the merits of biocompatibility and high-mechanics in periodontal ligament stem cells (PDLSCs) proliferation, attachment, and osteogenesis, hybrid hydrogel exhibits outstanding osteogenic potential both in vitro and in vivo. Importantly, it is the first time that a key epigenetic regulator of ten-eleven translocation 2 (Tet2) is discovered to significantly elevate the continuously active the WNT/β-catenin through Tet2/HDAC1/E-cadherin/β-catenin signaling cascade, thereby promoting PDLSCs osteogenesis. This work represents a general strategy to design the hydrogels with customized networks and biomimetic mechanics, and illustrates underlying osteogenic mechanisms that will extend the design rationales for high-functional biomaterials in tissue engineering.

Global scientific trends on the immunomodulation of mesenchymal stem cells in the 21st century: A bibliometric and visualized analysis

Background

Since the discovery of the immunomodulatory functions of mesenchymal stem cells (MSCs), their application in immunomodulation has attracted considerable attention, and an increasing number of studies have been conducted worldwide. Our research aimed to investigate the global status and trends in this field.

Methods

Publications on the immunomodulatory functions of MSCs from 1 January 2000 to 7 March 2022 were retrieved from the Web of Science Core Collection. The data were studied and indexed using the bibliometric methodology. Visualization analysis, co-authorship, co-occurrence analysis, and publication trends in MSC immunomodulation were conducted using the VOSviewer software.

Results

In total, 4,227 papers were included in the study. The number of publications and research interests has significantly increased globally. China published the highest number of related articles, while the US published articles with the highest number of citations. Stem Cell Research & Therapy had the highest number of publications. Sun Yat-sen University, Shanghai Jiao Tong University, Harvard University, and Seoul National University were the most contributive institutions. Furthermore, the studies were divided into four research hotspots for MSC immunomodulation: MSC immunomodulation in regenerative medicine, the effects and mechanisms of MSC immunomodulation, MSC therapy for immune diseases, and the cell source of MSCs.

Conclusion

This study indicates that the number of publications on MSC immunomodulation will increase in the future, and MSC immunomodulation mechanisms and clinical applications of MSC immunotherapy should be the next hotspots in this research field.

Exosome mediated biological functions within skeletal microenvironment

Exosomes are membranous lipid vesicles fused with intracellular multicellular bodies that are released into the extracellular environment. They contain bioactive substances, including proteins, RNAs, lipids, and cytokine receptors. Exosomes in the skeletal microenvironment are derived from a variety of cells such as bone marrow mesenchymal stem cells (BMSCs), osteoblasts, osteoclasts, and osteocytes. Their biological function is key in paracrine or endocrine signaling. Exosomes play a role in bone remodeling by regulating cell proliferation and differentiation. Genetic engineering technology combined with exosome-based drug delivery can therapy bone metabolic diseases. In this review, we summarized the pathways of exosomes derived from different skeletal cells (i.e., BMSCs, osteoblasts, osteocytes, and osteoclasts) regulate the skeletal microenvironment through proteins, mRNAs, and non-coding RNAs. By exploring the role of exosomes in the skeletal microenvironment, we provide a theoretical basis for the clinical treatment of bone-related metabolic diseases, which may lay the foundation to improve bone tumor microenvironments, alleviate drug resistance in patients.

The Role of Exosomes as Mediators of Neuroinflammation in the Pathogenesis and Treatment of Alzheimer’s Disease

Alzheimer’s disease (AD) is a common neurodegenerative disease characterized by progressive dementia. Accumulation of β–amyloid peptide 1–42 and phosphorylation of tau protein in the brain are the two main pathological features of AD. However, comprehensive studies have shown that neuroinflammation also plays a crucial role in the pathogenesis of AD. Neuroinflammation is associated with neuronal death and abnormal protein aggregation and promotes the pathological process of β-amyloid peptide 1–42 and tau protein. The inflammatory components associated with AD include glial cells, complement system, cytokines and chemokines. In recent years, some researchers have focused on exosomes, a type of membrane nano vesicles. Exosomes can transport proteins, lipids, microRNAs and other signaling molecules to participate in a variety of signaling pathways for signal transmission or immune response, affecting the activity of target cells and participating in important pathophysiological processes. Therefore, exosomes play an essential role in intercellular communication and may mediate neuroinflammation to promote the development of AD. This paper reviews the occurrence and development of neuroinflammation and exosomes in AD, providing a deeper understanding of the pathogenesis of AD. Furthermore, the role of exosomes in the pathogenesis and treatment of AD is further described, demonstrating their potential as therapeutic targets for neuroinflammation and AD in the future.

Long noncoding RNA Gm31629 promotes bone regeneration by maintaining bone marrow mesenchymal stem cells activity

Background

Long noncoding RNA Gm31629 can regulate hypothalamic neural stem cells (htNSCs) senescence and the aging process. However, the effect of Gm31629 on the senescence of bone marrow mesenchymal stem cells (BMSCs) and bone regeneration is unclear. In the present study, we investigated the effects of Gm31629 on the senescence of BMSCs and bone regeneration.

Methods

Gm31629 knockout (Gm31629-KO) and wild-type (WT) mice were used to establish a bone regeneration model. The Brdu labelling, CCK8 assay, wound healing assay, β-gal staining and osteogenic differentiation assay were used to assess the effects of Gm31629 on the functions of BMSCs. Micro-computed tomography (CT), histochemical and immunohistochemical staining were used to evaluate the ability of bone regeneration. The mimic of Gm31629, theaflavin 3-gallate, was used to investigate its role on the senescence of BMSCs and bone regeneration.

Results

The expression of Gm31629 reduced in BMSCs of middle-aged mice was compared with that of young mice. The deletion of Gm31629 was sufficient to drive the senescence of BMSCs, resulting in impaired bone regeneration in mice. Mechanistically, Gm31629 could interact with Y-box protein 1(YB-1) and delay its degradation, decreasing the transcription of p16^INK4A of BMSCs. We also found that theaflavin 3-gallate could alleviate the senescence of BMSCs and promote bone regeneration in middle-aged mice.

Conclusion

These results indicated that Gm31629 played an important role on BMSCs senescence and bone regeneration and provided a therapeutic target to promote bone regeneration.

Different Sources of Mesenchymal Stem Cells for Tissue Regeneration: A Guide to Identifying the Most Favorable One in Orthopedics and Dentistry Applications

The success of regenerative medicine in various clinical applications depends on the appropriate selection of the source of mesenchymal stem cells (MSCs). Indeed, the source conditions, the quality and quantity of MSCs, have an influence on the growth factors, cytokines, extracellular vesicles, and secrete bioactive factors of the regenerative milieu, thus influencing the clinical result. Thus, optimal source selection should harmonize this complex setting and ensure a well-personalized and effective treatment. Mesenchymal stem cells (MSCs) can be obtained from several sources, including bone marrow and adipose tissue, already used in orthopedic regenerative applications. In this sense, for bone, dental, and oral injuries, MSCs could provide an innovative and effective therapy. The present review aims to compare the properties (proliferation, migration, clonogenicity, angiogenic capacity, differentiation potential, and secretome) of MSCs derived from bone marrow, adipose tissue, and dental tissue to enable clinicians to select the best source of MSCs for their clinical application in bone and oral tissue regeneration to delineate new translational perspectives. A review of the literature was conducted using the search engines Web of Science, Pubmed, Scopus, and Google Scholar. An analysis of different publications showed that all sources compared (bone marrow mesenchymal stem cells (BM-MSCs), adipose tissue mesenchymal stem cells (AT-MSCs), and dental tissue mesenchymal stem cells (DT-MSCs)) are good options to promote proper migration and angiogenesis, and they turn out to be useful for gingival, dental pulp, bone, and periodontal regeneration. In particular, DT-MSCs have better proliferation rates and AT and G-MSC sources showed higher clonogenicity. MSCs from bone marrow, widely used in orthopedic regenerative medicine, are preferable for their differentiation ability. Considering all the properties among sources, BM-MSCs, AT-MSCs, and DT-MSCs present as potential candidates for oral and dental regeneration.

Progress of exosome research in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a global chronic autoimmune disease that invades most organs of the body, with kidney injury being the most prominent feature. Exosomes are extracellular vesicles that carry a variety of proteins, lipids and genetic material, participate in the exchange of local and intersystem information, and play an important immunoregulatory role in a variety of autoimmune diseases. At the same time, the use of exosomes as disease biomarkers and drug delivery carriers also shows great application prospects. This article reviews current progress in the application of exosomes in the pathogenesis, diagnosis and treatment of SLE.

Clinical Potential of Dental Pulp Stem Cells in Pulp Regeneration: Current Endodontic Progress and Future Perspectives

Dental caries is a common disease that not only destroys the rigid structure of the teeth but also causes pulp necrosis in severe cases. Once pulp necrosis has occurred, the most common treatment is to remove the damaged pulp tissue, leading to a loss of tooth vitality and increased tooth fragility. Dental pulp stem cells (DPSCs) isolated from pulp tissue exhibit mesenchymal stem cell-like characteristics and are considered ideal candidates for regenerating damaged dental pulp tissue owing to their multipotency, high proliferation rate, and viability after cryopreservation. Importantly, DPSCs do not elicit an allogeneic immune response because they are non-immunogenic and exhibit potent immunosuppressive properties. Here, we provide an up-to-date review of the clinical applicability and potential of DPSCs, as well as emerging trends in the regeneration of damaged pulp tissue. In addition, we suggest the possibility of using DPSCs as a resource for allogeneic transplantation and provide a perspective for their clinical application in pulp regeneration.

Amniotic membrane mesenchymal stem cells-based therapy improves Bmi-1-deficient mandible osteoporosis through stimulating osteoblastic bone formation and inhibiting osteoclastic bone resorption

Mandible osteoporosis with age is characterized by greater fragility and accompanied with abnormal oral function. Mesenchymal stem cell transplantation can ameliorate osteoporosis. Bmi-1 is a transcriptional repressor which is an important regulator of cell cycle, stem cells self-renewal, and cell senescence. Here, we use a new kind of membrane mesenchymal stem cells (MSCs), amniotic membrane mesenchymal stem cells (AMSCs), to explore therapeutic effects on Bmi-1-deficient caused mandible osteoporosis. Phenotypes of mandibles from 5-week-old Bmi-1-deficient mice with AMSCs-based therapy were compared with age-matched Bmi-1-deficient mandibles without AMSCs-based therapy and wild-type mice. Bmi-1-deficient mice without AMSCs-based therapy displayed mandible osteoporosis accompanied with the rising senescence-associated molecules and imbalance redox homeostasis. Results showed that the alveolar bone volume, cortical thickness, type I collagen and osteocalcin immunopositive areas, mRNA expression levels of alkaline phosphatase, superoxide dismutase, gluathione reductase, and protein expression level of Runx2 were all reduced significantly in Bmi-1^-/- mandibles. Protein levels of PPARγ, p16, p21, p53, and redox gene levels of Bnip3l, Cdo1, Duox1, and Duox2 were up-regulated in mandibles from vehicle-transplanted Bmi-1^-/- mice. Also, osteoclasts were activated in Bmi-1^-/- alveolar bone. Transplanted AMSCs migrated into mandibles and improved all the parameters in Bmi-1^-/- mandibles with AMSCs-based therapy. These findings indicate that AMSCs-based therapy could rescue mandible osteoporosis induced by Bmi-1 deficiency through stimulating osteoblastic bone formation and inhibiting osteoclastic bone resorption. Our findings implied that AMSCs-based therapy had preventative and therapeutic potential for mandible osteoporosis.

Rescuing effects of periostin in advanced glycation end-products (AGEs) caused osteogenic and oxidative damage through AGE receptor mediation and DNA methylation of the CALCA promoter

An in vitro model was established to simulate a diabetes-type environment by treating human periodontal stem cells with advanced glycation end-products (AGEs). Periostin (POSTN) plays a crucial role in maintaining the integrity of periodontal tissues. However, the role of POSTN in human periodontal stem cells stimulated by AGEs remains unknown. Diabetes mellitus is considered a metabolic disease, and DNA methylation of CpG islands is a biomarker of metabolic syndromes. Diabetes has been found to be closely related to the DNA methylation of certain genes. Here, we investigated the protective mechanism and effect of POSTN on osteogenesis and oxidative stress in the AGE environment, and further explored the CpG island methylation of specific genes potentially mediated by POSTN. The optimal concentration of AGEs was screened using CCK8. AGEs were found to contribute to oxidative stress. Conversely, reactive oxygen species production and malondialdehyde and superoxide activity indicated that the AGE + POSTN group decreased oxidative injury. According to an alkaline phosphatase assay, Alizarin Red S staining, and the expression of key genes and proteins involved in osteogenesis, POSTN mitigated the inhibitory effects of AGE on cell proliferation and osteogenic differentiation potential during osteogenic differentiation. In contrast, the growth and osteogenesis of human periodontal stem cells were notably suppressed by POSTN knockdown. Bisulfite sequencing PCR was used to evaluate the DNA methylation status. Moreover, AGE elevated the expression of DNA methyltransferas 1 (DNMT1) and inhibited the activation of CALAL promoter methylation, which was rescued by the addition of POSTN and 5-Azacytidine (5-AZA). In conclusion, POSTN attenuated the AGE-induced inhibition of osteogenesis in periodontal ligament stem cells by reducing AGE receptor levels and DNA methylation of the calcitonin-related polypeptide α (CALCA) promoter. Thus, POSTN is a promising candidate for dental bone regeneration, representing a novel therapeutic agent for diabetic patients. The mechanism underlying these processes may provide new insights into novel therapeutic targets for improving abnormal bone metabolism in patients with diabetes.

Periodontal Ligament Stem Cell-Derived Small Extracellular Vesicles Embedded in Matrigel Enhance Bone Repair Through the Adenosine Receptor Signaling Pathway

Purpose

Small extracellular vesicles (sEVs) are natural biocarriers for biomolecule transfer between cells and promising therapeutic strategies for bone defect repair. In this study, human periodontal ligament stem cell (PDLSC)-derived sEVs (P-EVs) were immobilized in Matrigel to establish a topical cell-free transplantation strategy for bone repair.

Methods

PDLSCs were cultured and P-EVs were isolated from the culture supernatant. In a rat bilateral calvarial defect model, P-EV/Matrigel was plugged into one defect and PBS/Matrigel was applied to the other. Bone repair in vivo was assessed by micro-computed tomography, histomorphometry, and immunohistochemical staining. In vitro, we investigated the effects of P-EVs on the proliferation and migration capabilities of bone marrow mesenchymal stem cells (BMMSCs) and explored the potential mechanism of action.

Results

The in vivo study showed that P-EV/Matrigel accelerated bone tissue repair by increasing cell infiltration when compared with the control. In vitro, P-EVs enhanced proliferation and migration of BMMSCs via increased phosphorylation of AKT and extracellular signal-regulated kinase 1/2 (ERK1/2). The role of P-EV-induced adenosine receptor signaling in AKT and ERK1/2 phosphorylation was a key mediator during enhanced BMMSC migration.

Conclusion

These results are the first to demonstrate that P-EVs accelerated the repair of bone defects, partially through promoting cell proliferation and migration. P-EV/Matrigel, which combines topical EV-implantation and extracellular matrix scaffolds, provides a new cell-free strategy for bone tissue repair.

Exosomes: A Tool for Bone Tissue Engineering

Mesenchymal stem cells (MSCs) have been repeatedly shown to be a valuable source for cell-based therapy in regenerative medicine, including bony tissue repair. However, engraftment at the injury site is poor. Recently, it has been suggested that MSCs and other cells act through a paracrine signaling mechanism. Exosomes are nanostructures that have been implicated in this process. They carry DNA, RNA, proteins, and lipids and play an important role in cell-to-cell communication directly modulating their target cell at a transcriptional level. In a bone microenvironment, they have been shown to increase osteogenesis and osteogenic differentiation in vivo and in vitro. In the following review, we will discuss the most advanced and significant knowledge of biological functions of exosomes in bone regeneration and their clinical applications in osseous diseases. Impact statement Mesenchymal stem cells have been shown to be a promising tool in bone tissue engineering. Recently, it has been suggested that they secrete exosomes containing messenger RNA, proteins, and lipids, thus acting through paracrine signaling mechanisms. Considering that exosomes are nonteratogenic and have low immunogenic potential, they could potentially replace stem-cell based therapy and thus eradicate the risk of neoplastic transformation associated with cell transplantations in bone regeneration.

Role of Exosomal Non-Coding RNAs in Bone-Related Diseases

Bone-related diseases seriously affect the lives of patients and carry a heavy economic burden on society. Treatment methods cannot meet the diverse clinical needs of affected patients. Exosomes participate in the occurrence and development of many diseases through intercellular communication, including bone-related diseases. Studies have shown that exosomes can take-up and “package” non-coding RNAs and “deliver” them to recipient cells, thereby regulating the function of recipient cells. The exosomal non-coding RNAs secreted by osteoblasts, osteoclasts, chondrocytes, and other cells are involved in the regulation of bone-related diseases by inhibiting osteoclasts, enhancing chondrocyte activity and promoting angiogenesis. Here, we summarize the role and therapeutic potential of exosomal non-coding RNAs in the bone-related diseases osteoporosis, osteoarthritis, and bone-fracture healing, and discuss the clinical application of exosomes in patients with bone-related diseases.

Epigenetic modifications of histones during osteoblast differentiation

In bone biology, epigenetics plays a key role in mesenchymal stem cells' (MSCs) commitment towards osteoblasts. It involves gene regulatory mechanisms governed by chromatin modulators. Predominant epigenetic mechanisms for efficient osteogenic differentiation include DNA methylation, histone modifications, and non-coding RNAs. Among these mechanisms, histone modifications critically contribute to altering chromatin configuration. Histone based epigenetic mechanisms are an essential mediator of gene expression during osteoblast differentiation as it directs the bivalency of the genome. Investigating the importance of histone modifications in osteogenesis may lead to the development of epigenetic-based remedies for genetic disorders of bone. Hence, in this review, we have highlighted the importance of epigenetic modifications such as post-translational modifications of histones, including methylation, acetylation, phosphorylation, ubiquitination, and their role in the activation or suppression of gene expression during osteoblast differentiation. Further, we have emphasized the future advancements in the field of epigenetics towards orthopaedical therapeutics.

The Emerging Roles and Therapeutic Implications of Epigenetic Modifications in Ovarian Cancer

Ovarian cancer (OC) is one of the most lethal gynecologic malignancies globally. In spite of positive responses to initial therapy, the overall survival rates of OC patients remain poor due to the development of drug resistance and consequent cancer recurrence. Indeed, intensive studies have been conducted to unravel the molecular mechanisms underlying OC therapeutic resistance. Besides, emerging evidence suggests a crucial role for epigenetic modifications, namely, DNA methylation, histone modifications, and non-coding RNA regulation, in the drug resistance of OC. These epigenetic modifications contribute to chemoresistance through various mechanisms, namely, upregulating the expression of multidrug resistance proteins (MRPs), remodeling of the tumor microenvironment, and deregulated immune response. Therefore, an in-depth understanding of the role of epigenetic mechanisms in clinical therapeutic resistance may improve the outcome of OC patients. In this review, we will discuss the epigenetic regulation of OC drug resistance and propose the potential clinical implications of epigenetic therapies to prevent or reverse OC drug resistance, which may inspire novel treatment options by targeting resistance mechanisms for drug-resistant OC patients.

Made by cells for cells - extracellular vesicles as next-generation mainstream medicines

Current medicine has only taken us so far in reducing disease and tissue damage. Extracellular vesicles (EVs), which are membranous nanostructures produced naturally by cells, have been hailed as a next-generation medicine. EVs deliver various biomolecules, including proteins, lipids and nucleic acids, which can influence the behaviour of specific target cells. Since EVs not only mirror composition of their parent cells but also modify the recipient cells, they can be used in three key areas of medicine: regenerative medicine, disease detection and drug delivery. In this Review, we discuss the transformational and translational progress witnessed in EV-based medicine to date, focusing on two key elements: the mechanisms by which EVs aid tissue repair (for example, skin and bone tissue regeneration) and the potential of EVs to detect diseases at an early stage with high sensitivity and specificity (for example, detection of glioblastoma). Furthermore, we describe the progress and results of clinical trials of EVs and demonstrate the benefits of EVs when compared with traditional medicine, including cell therapy in regenerative medicine and solid biopsy in disease detection. Finally, we present the challenges, opportunities and regulatory framework confronting the clinical application of EV-based products.

Long-term efficacy of autologous bone marrow mesenchymal stromal cells for treatment of knee osteoarthritis

Knee osteoarthritis is the most prevalent joint disease and a frequent cause of pain, functional loss and disability. Conventional treatments have demonstrated only modest clinical benefits whereas cell-based therapies have shown encouraging results, but important details, such as dose needed, long-term evolution or number of applications required are scarcely known. Here we have reanalyzed results from two recent pilot trials with autologous bone marrow-derived mesenchymal stromal cells using the Huskisson plot to enhance quantification of efficacy and comparability. We find that cell doses of 10, 40 and 100 million autologous cells per knee provided quite similar healing results and that much of the effect attained 1 year after cell application remained after 2 and 4 years. These results are encouraging because they indicate that, apart from safety and simplicity: (i) the beneficial effect is both significant and sizeable, (ii) it can be achieved with a single injection of cells, and (iii) the effect is perdurable for years.Trial registration: EudraCT 2009-017405-11; NCT02123368. Registered 25 April 2014-Prospectively registered, https://clinicaltrials.gov/ct2/show/NCT02123368?term=02123368&draw=2&rank=1.