Extracellular vesicle and mesenchymal stem cells in bone regeneration: recent progress and perspectives

Stem Cell and Regenerative Therapies for the Treatment of Osteoporotic Vertebral Compression Fractures

Osteoporotic vertebral compression fractures (OVCFs) significantly increase morbidity and mortality, presenting a formidable challenge in healthcare. Traditional interventions such as vertebroplasty and kyphoplasty, despite their widespread use, are limited in addressing the secondary effects of vertebral fractures in adjacent areas and do not facilitate bone regeneration. This review paper explores the emerging domain of regenerative therapies, spotlighting stem cell therapy's transformative potential in OVCF treatment. It thoroughly describes the therapeutic possibilities and mechanisms of action of mesenchymal stem cells against OVCFs, relying on recent clinical trials and preclinical studies for efficacy assessment. Our findings reveal that stem cell therapy, particularly in combination with scaffolding materials, holds substantial promise for bone regeneration, spinal stability improvement, and pain mitigation. This integration of stem cell-based methods with conventional treatments may herald a new era in OVCF management, potentially improving patient outcomes. This review advocates for accelerated research and collaborative efforts to translate laboratory breakthroughs into clinical practice, emphasizing the revolutionary impact of regenerative therapies on OVCF management. In summary, this paper positions stem cell therapy at the forefront of innovation for OVCF treatment, stressing the importance of ongoing research and cross-disciplinary collaboration to unlock its full clinical potential.

Functionalized 3D Hydroxyapatite Scaffold by Fusion Peptides-Mediated Small Extracellular Vesicles of Stem Cells for Bone Tissue Regeneration

3D printing technology offers extensive applications in tissue engineering and regenerative medicine (TERM) because it can create a three-dimensional porous structure with acceptable porosity and fine mechanical qualities that can mimic natural bone. Hydroxyapatite (HA) is commonly used as a bone repair material due to its excellent biocompatibility and osteoconductivity. Small extracellular vesicles (sEVs) derived from bone marrow mesenchymal stem cells (BMSCs) can regulate bone metabolism and stimulate the osteogenic differentiation of stem cells. This study has designed a functionalized bone regeneration scaffold (3D H-P-sEVs) by combining the biological activity of BMSCs-sEVs and the 3D-HA scaffold to improve bone regeneration. The scaffold utilizes the targeting of fusion peptides to increase the loading efficiency of sEVs. The composition, structure, mechanical properties, and in vitro degradation performance of the 3D H-P-sEVs scaffolds were examined. The composite scaffold demonstrated good biocompatibility, substantially increased the expression of osteogenic-related genes and proteins, and had a satisfactory bone integration effect in the critical skull defect model of rats. In conclusion, the combination of EVs and 3D-HA scaffold via fusion peptide provides an innovative composite scaffold for bone regeneration and repair, improving osteogenic performance.

Extracellular Vesicles and Immunity: At the Crossroads of Cell Communication

Extracellular vesicles (EVs), comprising exosomes and microvesicles, are small membranous structures secreted by nearly all cell types. They have emerged as crucial mediators in intercellular communication, playing pivotal roles in diverse physiological and pathological processes, notably within the realm of immunity. These roles go beyond mere cellular interactions, as extracellular vesicles stand as versatile and dynamic components of immune regulation, impacting both innate and adaptive immunity. Their multifaceted involvement includes immune cell activation, antigen presentation, and immunomodulation, emphasising their significance in maintaining immune homeostasis and contributing to the pathogenesis of immune-related disorders. Extracellular vesicles participate in immunomodulation by delivering a wide array of bioactive molecules, including proteins, lipids, and nucleic acids, thereby influencing gene expression in target cells. This manuscript presents a comprehensive review that encompasses in vitro and in vivo studies aimed at elucidating the mechanisms through which EVs modulate human immunity. Understanding the intricate interplay between extracellular vesicles and immunity is imperative for unveiling novel therapeutic targets and diagnostic tools applicable to various immunological disorders, including autoimmune diseases, infectious diseases, and cancer. Furthermore, recognising the potential of EVs as versatile drug delivery vehicles holds significant promise for the future of immunotherapies.

Regulating pyroptosis by mesenchymal stem cells and extracellular vesicles: A promising strategy to alleviate intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is a main cause of low back pain (LBP), which can lead to disability and thus generate a heavy burden on society. IVDD is characterized by a decrease in nucleus pulposus cells (NPCs) and endogenous mesenchymal stem cells (MSCs), degradation of the extracellular matrix, macrophage infiltration, and blood vessel and nerve ingrowth. To date, the therapeutic approaches regarding IVDD mainly include conservative treatment and surgical intervention. However, both can only relieve symptoms rather than stop or revert the progression of IVDD, since the pathogenesis of IVDD is not yet clear. Pyroptosis, which is characterized by Caspase family dependence and conducted by the Gasdermin family, is a newly discovered mode of programmed cell death. Pyroptosis has been observed in NPCs, annulus fibrosus cells (AFCs), chondrocytes, MSCs, macrophages, vascular endothelial cells and neurons and may contribute to IVDD. MSCs are a kind of pluripotent stem cell that can be found in almost all tissues. MSCs have a strong ability to secrete extracellular vesicles (EVs), which contain exosomes, microvesicles and apoptotic bodies. EVs derived from MSCs play an important role in pyroptosis regulation and could be beneficial for alleviating IVDD. This review focuses on clarifying the regulation of pyroptosis to improve IVDD by MSCs and EVs derived from MSCs.

Pathophysiology and Therapeutic Management of Bone Loss in Patients with Critical Illness

Patients with critical illnesses are at higher risk of comorbidities, which can include bone mineral density loss, bone turnover marker increase, and fragility fractures. Patients admitted to intensive care units (ICUs) have a higher risk of bone fractures. Since hypermetabolism is a characteristic of ICU patients, such patients are often rapidly affected by systemic deterioration, which often results in systemic wasting disease. Major risk factors for ICU-related bone loss include physical restraint, inflammation, neuroendocrine stress, malnutrition, and medications. A medical history of critical illness should be acknowledged as a risk factor for impaired bone metabolism. Bone loss associated with ICU admission should be recognized as a key component of post-intensive care syndrome, and further research that focuses on treatment protocols and prevention strategies is required. Studies aimed at maintaining gut integrity have emphasized protein administration and nutrition, while research is ongoing to evaluate the therapeutic benefits of anti-resorptive agents and physical therapy. This review examines both current and innovative clinical strategies that are used for identifying risk factors of bone loss. It provides an overview of perioperative outcomes and discusses the emerging novel treatment modalities. Furthermore, the review presents future directions in the treatment of ICU-related bone loss.

Human nasal mucosa ectomesenchymal stem cells derived extracellular vesicles loaded omentum/chitosan composite scaffolds enhance skull defects regeneration

Engineered bone tissue that can promote osteogenic differentiation is considered an ideal substitute for materials to heal bone defects. Extracellular vesicle (EV)-based cell-free regenerative therapies represent an emerging promising alternative for bone tissue engineering. We hypothesized that EVs derived from human nasal mucosa-derived ectomesenchymal stem cells (hEMSCs) can promote bone tissue regeneration. Herein, hEMSCs were cultured with osteogenic induction medium or normal medium to generate two types of EVs. We first demonstrated that the two EVs exhibited strong potential to promote rat suture mesenchymal stem cell (SMSC) osteogenesis by transferring TG2 to SMSCs and regulating extracellular matrix (ECM) synthesis. Next, we developed a composite hydrogel made of porcine omentum and chitosan into which EVs were adsorbed to enable the effective delivery of EVs with sustained release kinetics. Implantation of the EV-loaded hydrogels in a critical-size rat cranial defect model significantly promoted bone regeneration. Therefore, we suggest that our hEMSC-derived EV-loading system can serve as a new therapeutic paradigm for promoting bone tissue regeneration in the clinic.

Clinical Potential of Mesenchymal Stem Cell-Derived Exosomes in Bone Regeneration

Bone metabolism is regulated by osteoblasts, osteoclasts, osteocytes, and stem cells. Pathologies such as osteoporosis, osteoarthritis, osteonecrosis, and traumatic fractures require effective treatments that favor bone formation and regeneration. Among these, cell therapy based on mesenchymal stem cells (MSC) has been proposed. MSC are osteoprogenitors, but their regenerative activity depends in part on their paracrine properties. These are mainly mediated by extracellular vesicle (EV) secretion. EV modulates regenerative processes such as inflammation, angiogenesis, cell proliferation, migration, and differentiation. Thus, MSC-EV are currently an important tool for the development of cell-free therapies in regenerative medicine. This review describes the current knowledge of the effects of MSC-EV in the different phases of bone regeneration. MSC-EV has been used by intravenous injection, directly or in combination with different types of biomaterials, in preclinical models of bone diseases. They have shown great clinical potential in regenerative medicine applied to bone. These findings should be confirmed through standardization of protocols, a better understanding of the mechanisms of action, and appropriate clinical trials. All that will allow the translation of such cell-free therapy to human clinic applications.

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.

ESP-B4 promotes nasal epithelial cell-derived extracellular vesicles containing miR-146a-5p to modulate Smad3/GATA-3 thus relieving allergic rhinitis: ESP-B4/miR-146a-5p in AR

BACKGROUND

Though generally a mild affliction, allergic rhinitis (AR) is very common and causes considerable discomfort. Ephedra sinica polysaccharide is a candidate cost-effective therapy to relieve AR symptoms.

PURPOSE

We explore the molecular mechanism of pure polysaccharide ESP-B4 action in AR.

METHODS

RPMI2650 cells were treated with lipopolysaccharide to induce an in vitro sensitization model, and extracellular vesicles (EVs) were isolated. A rat model of AR was established using ovalbumin as the allergen and was treated with Ephedra sinica polysaccharide to observe changes in rhinitis symptoms, nasal mucosa histopathology and molecular pathology. ESP-B4-treated sensitized cells were adopted in vitro to verify effect of Ephedra sinica polysaccharide on miR-146a-5p expression in RPMI2650 cell-derived EVs and helper T cell differentiation.

RESULTS

miR-146a-5p inhibited Smad3, impeded the Smad3/GATA-3 interaction, upregulated IFN-γ expression, and promoted CD4⁺T cell Th1 differentiation. Treatment with ESP-B4 relieved AR in rats, and elevated miR-146a-5p in the EVs from the nasal epithelial cells, apparently in relation to effects on helper T cell Th1/Th2 equilibrium.

CONCLUSION

Overall, ESP-B4 can promote miR-146a-5p secretion, affect the Th1/Th2 balance of helper T cells, and relieve AR symptoms through Smad3/GATA-3 interaction, thus presenting a potential strategy for AR treatment.

Osteochondral regenerative engineering: challenges, state-of-the-art and translational perspectives

Despite quantum leaps, the biomimetic regeneration of cartilage and osteochondral regeneration remains a major challenge, owing to the complex and hierarchical nature of compositional, structural and functional properties. In this review, an account of the prevailing challenges in biomimicking the gradients in porous microstructure, cells and extracellular matrix (ECM) orientation is presented. Further, the spatial arrangement of the cues in inducing vascularization in the subchondral bone region while maintaining the avascular nature of the adjacent cartilage layer is highlighted. With rapid advancement in biomaterials science, biofabrication tools and strategies, the state-of-the-art in osteochondral regeneration since the last decade has expansively elaborated. This includes conventional and additive manufacturing of synthetic/natural/ECM-based biomaterials, tissue-specific/mesenchymal/progenitor cells, growth factors and/or signaling biomolecules. Beyond the laboratory-based research and development, the underlying challenges in translational research are also provided in a dedicated section. A new generation of biomaterial-based acellular scaffold systems with uncompromised biocompatibility and osteochondral regenerative capability is necessary to bridge the clinical demand and commercial supply. Encompassing the basic elements of osteochondral research, this review is believed to serve as a standalone guide for early career researchers, in expanding the research horizon to improve the quality of life of osteoarthritic patients affordably.

Gene-activated titanium implants for gene delivery to enhance osseointegration

Osseointegration is the direct and intimate contact between mineralized tissue and titanium implant at the bone-implant interface. Early establishment and stable maintenance of osseointegration is the key to long-term implant success. However, in patients with compromised conditions such as osteoporosis and patients beginning early load-bearing activities such as walking, lower osseointegration around titanium implants is often observed, which might result in implant early failure. Gene-activated implants show an exciting prospect of combining gene delivery and biomedical implants to solve the problems of poor osseointegration formation, overcoming the shortcomings of protein therapy, including rapid degradation and overdose adverse effects. The conception of gene-activated titanium implants is based on "gene-activated matrix" (GAM), which means scaffolds using non-viral vectors for in situ gene delivery to achieve a long-term and efficient transfection of target cells. Current preclinical studies in animal models have shown that plasmid DNA (pDNA), microRNA (miRNA), and small interference RNA (siRNA) functionalized titanium implants can enhance osseointegration with safety and efficiency, leading to the expectation of applying this technique in dental and orthopedic clinical scenarios. This review aims to comprehensively summarize fabrication strategies, current applications, and futural outlooks of gene-activated implants, emphasizing nucleic acid targets, non-viral vectors, implant surface modification techniques, nucleic acid/vector complexes loading strategies.

Ginsenoside Rb1 prevents osteoporosis via the AHR/PRELP/NF-κB signaling axis

BACKGROUND

Accumulating clinical and experimental evidence shows multiple biological effects of ginsenoside Rb1 (GRb1) in the treatment of aging related diseases such as osteoporosis (OP). Recently, GRb1 has attracted extensive attention as an anti-osteoporosis agent. Here, we sought to identify the mechanism by which GRb1 improves OP.

METHODS

A dexamethasone (DEX)-induced rat model of OP was constructed and the rats were treated with GRb1 to examine its role in OP. We screened the action targets of GRb1 online and validated by performing functional experiments. The correlation between aryl hydrocarbon receptor (AHR) and proline/arginine-rich end leucine-rich repeat protein (PRELP) was identified through luciferase and chromatin immunoprecipitation assays. In the isolated osteoblasts from DEX-induced OP rats, the expression of osteogenic differentiation-associated genes, and nuclear factor-kappa B (NF-κB) pathway-related genes, mineralization, and number of calcium nodules were assessed.

RESULTS

GRb1 enhanced the differentiation of osteoblasts, the mechanism of which was related to upregulation of AHR. AHR could promote the transcription of PRELP by binding to the PRELP promoter region and consequently caused its upregulation. Meanwhile, PRELP inhibited the activation of the NF-κB pathway, which underlay the promoting impact of AHR in the osteogenic differentiation. Additionally, GRb1 could ameliorate OP in DEX-induced rats via the AHR/PRELP/NF-κB axis.

CONCLUSIONS

Our findings demonstrate that GRb1 might function as an effective candidate to prevent the progression of OP via regulation of the AHR/PRELP/NF-κB axis, revealing a new molecular mechanism underpinning the impact of GRb1 in the progression of OP and offering a theoretical contribution to the treatment of OP.

Engineered Delivery of Dental Stem-Cell-Derived Extracellular Vesicles for Periodontal Tissue Regeneration

Periodontal disease begins as an inflammatory response to a bacterial biofilm deposited around the teeth, which over time leads to the destruction of tooth-supporting structures and consequently tooth loss. Conventional treatment strategies show limited efficacy in promoting regeneration of damaged periodontal tissues. Here, a delivery platform is developed for small extracellular vesicles (sEVs) derived from gingival mesenchymal stem cells (GMSCs) to treat periodontitis. EVs can achieve comparable therapeutic effects to their cells of origin. However, the short half-lives of EVs after their administration along with their rapid diffusion away from the delivery site necessitate frequent administration to achieve therapeutic benefits. To address these issues, "dual delivery" microparticles are engineered enabling microenvironment-sensitive release of EVs by metalloproteinases at the affected site along with antibiotics to suppress bacterial biofilm growth. GMSC sEVs are able to decrease the secretion of pro-inflammatory cytokines by monocytes/macrophages and T cells, suppress T-cell activation, and induce the formation of T regulatory cells (Tregs) in vitro and in a rat model of periodontal disease. One-time administration of immunomodulatory GMSC sEV-decorated microparticles leads to a significant improvement in regeneration of the damaged periodontal tissue. This approach will have potential clinical applications in the regeneration of a variety of tissues.

Extracellular vesicles released from hiPSC-derived MSCs attenuate chronic prostatitis/chronic pelvic pain syndrome in rats by immunoregulation

BACKGROUND

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is an intractable nonbacterial inflammatory disease. Mesenchymal stem cells (MSCs) derived from human induced pluripotent stem cells (hiPSCs, iMSCs) have been well documented for the management of inflammatory and autoimmune disorders because of their powerful immunoregulatory and anti-inflammatory capacities. Recently, studies have indicated that extracellular vesicles (EVs) released from iMSCs hold biological functions similar to their parental cells. This study aimed to evaluate the therapeutic efficacy of EVs released from iMSCs (iMSCs-EVs) on CP/CPPS and to explore the underlying mechanisms.

METHODS

An experimental autoimmune prostatitis (EAP) model was established in rats by subcutaneous injection of prostate antigen with adjuvant. Then, iMSCs-EVs were injected into EAP rats via the tail vein. Pain behavioral measurements, urodynamic tests, and histopathological analyses were performed at 2, 4, and 6 weeks. The expression of cyclooxygenase-2 (COX-2) was evaluated by immunofluorescence staining and Western blot. The alterations of B cells, Th1 cells, Th2 cells, Th17 cells, and Treg cells in peripheral blood and spleen were analyzed using flow cytometry. The levels of Th1-, Th2-, Th17-, and Treg-related inflammatory mediators were determined by ELISA.

RESULTS

After iMSCs-EVs administration, rats had reduced pain as indicated by the recovery of nociceptive responses to baseline. The voiding pressure was significantly reduced, and the intercontraction interval was increased. The findings of histopathological analysis revealed that iMSCs-EVs could significantly decrease inflammatory cell infiltration and promote basal lamina and glandular epithelial tissue repair. Further studies demonstrated that the overexpression of COX-2 was downregulated by iMSCs-EVs. Meanwhile, the increases in the percentages of Th1 and Th17 cells were dramatically reversed. Also, rats that received iMSCs-EVs showed markedly increased percentages of Treg cells. The levels of those inflammatory mediators showed the same changing tendency.

CONCLUSIONS

iMSCs-EVs administration has the potential to ameliorate chronic pelvic pain, improve voiding dysfunction, suppress inflammatory reactions, and facilitate prostatic tissue repair. The functions are mediated by downregulating the overexpression of COX-2 and restoring the imbalance of Th1/Th2 and Treg/Th17 cells.

Comparisons of Extracellular Vesicles from Human Epidural Fat-Derived Mesenchymal Stem Cells and Fibroblast Cells

Extracellular vesicles (EVs) are generated and secreted by cells into the circulatory system. Stem cell-derived EVs have a therapeutic effect similar to that of stem cells and are considered an alternative method for cell therapy. Accordingly, research on the characteristics of EVs is emerging. EVs were isolated from human epidural fat-derived mesenchymal stem cells (MSCs) and human fibroblast culture media by ultracentrifugation. The characterization of EVs involved the typical evaluation of cluster of differentiation (CD antigens) marker expression by fluorescence-activated cell sorting, size analysis with dynamic laser scattering, and morphology analysis with transmission electron microscopy. Lastly, the secreted levels of cytokines and chemokines in EVs were determined by a cytokine assay. The isolated EVs had a typical size of approximately 30–200 nm, and the surface proteins CD9 and CD81 were expressed on human epidural fat MSCs and human fibroblast cells. The secreted levels of cytokines and chemokines were compared between human epidural fat MSC-derived EVs and human fibroblast-derived EVs. Human epidural fat MSC-derived EVs showed anti-inflammatory effects and promoted macrophage polarization. In this study, we demonstrated for the first time that human epidural fat MSC-derived EVs exhibit inflammatory suppressive potency relative to human fibroblast-derived EVs, which may be useful for the treatment of inflammation-related diseases.

Mesenchymal stem cell-derived small extracellular vesicles as cell-free therapy: Perspectives in periodontal regeneration

Mesenchymal stem cells (MSC) are involved in the regeneration of the different missing or compromised periodontal tissues. MSC-derived small extracellular vesicles (sEV) have recently been explored as a favorable substitution for stem cell therapy, as they are capable of producing therapeutic effects comparable to those of their parent cells, with advantages over cell therapy. The aim of this review is to evaluate the use of mesenchymal stem cells (MSC)-derived sEV as cell-free therapy in periodontal regeneration. A review of the scientific literature on sEV and their use in periodontal regeneration was performed. The main characteristics of sEV are described, and their mechanisms of action and potential biological effects in periodontal regeneration are studied. A summary of existing preclinical studies conducted in animals is performed. The results indicate that sEV derived from MSC are emerging as a promising new therapeutic tool in the field of periodontal regeneration and may become an ideal therapeutic option. In this review, we have summarized recent advances in this regard in order to better understand this newly emerging treatment. First results in vivo are promising and show a favorable potential for cell-free therapy in periodontal regeneration.

A Review of the Functions of Matrix Vesicles in Periodontal Tissues

Periodontal tissues consist of cementum, periodontal ligaments, and alveolar bone, which provide indispensable support for physiological activities involving mastication, swallowing, and pronunciation. The formation of periodontal tissues requires a complex process, during which a close relationship with biomineralization is noticeable. Alveolar bone and cementum are physically hard, both of which are generated from biomineralization and possess the exact mechanical properties resembling other hard tissues. However, when periodontitis, congenital abnormalities, periapical diseases, and other pathological conditions affect the organism, the most common symptom, alveolar bone defect, is always unavoidable, which results in difficulties for current clinical treatment. Thus, exploring effective therapies to improve the prognosis is important. Matrix vesicles (MVs), a special subtype of extracellular vesicles related to histogenesis, are widely produced by the stem cells of developing hard tissues. With the assistance of the enzymes and transporters contained within them, MVs can construct the extracellular matrix and an adequate microenvironment, thus promoting biomineralization and periodontal development. Presently, MVs can be effectively extracted and delivered by scaffolds and generate hard tissues in vitro and in vivo, which are expected to be translated into therapies for alveolar bone defects. In this review, we generalize recent research progress on MV morphology, molecular composition, biological mechanism, and, in particular, the biological functions in periodontal development. In addition to the above unique roles of MVs, we further describe the available MV-related biotechnologies and achievements that make them promising for coping with existing problems and improving the treatment of alveolar bone defects.

Additive manufacturing pertaining to bone: Hopes, reality and future challenges for clinical applications

For the past 20 years, the democratization of additive manufacturing (AM) technologies has made many of us dream of: low cost, waste-free, and on-demand production of functional parts; fully customized tools; designs limited by imagination only, etc. As every patient is unique, the potential of AM for the medical field is thought to be considerable: AM would allow the division of dedicated patient-specific healthcare solutions entirely adapted to the patients' clinical needs. Pertinently, this review offers an extensive overview of bone-related clinical applications of AM and ongoing research trends, from 3D anatomical models for patient and student education to ephemeral structures supporting and promoting bone regeneration. Today, AM has undoubtably improved patient care and should facilitate many more improvements in the near future. However, despite extensive research, AM-based strategies for bone regeneration remain the only bone-related field without compelling clinical proof of concept to date. This may be due to a lack of understanding of the biological mechanisms guiding and promoting bone formation and due to the traditional top-down strategies devised to solve clinical issues. Indeed, the integrated holistic approach recommended for the design of regenerative systems (i.e., fixation systems and scaffolds) has remained at the conceptual state. Challenged by these issues, a slower but incremental research dynamic has occurred for the last few years, and recent progress suggests notable improvement in the years to come, with in view the development of safe, robust and standardized patient-specific clinical solutions for the regeneration of large bone defects.

Extracellular Vesicle-Encapsulated miR-29b-3p Released From Bone Marrow-Derived Mesenchymal Stem Cells Underpins Osteogenic Differentiation

Objective

Mesenchymal stem cells (MSCs) confer therapeutic benefits in various pathologies and cancers by releasing extracellular vesicles (EVs) loaded with bioactive compounds. Herein, we identified bone marrow MSC (BMSC)-derived EVs harboring microRNA (miR)-29b-3p to regulate osteogenic differentiation through effects on the suppressor of cytokine signaling 1 (SOCS1)/nuclear factor (NF)-κB pathway via targeting of lysine demethylase 5A (KDM5A) in osteoporosis.

Methods

We quantified the miR-29b-3p in BMSC-derived EVs from bone marrow specimens of osteoporotic patients and non-osteoporotic patients during total hip arthroplasty (THA). miR-29b-3p targeting KDM5A was confirmed by promoter luciferase assay, and enrichment of KDM5A in the promoter region of SOCS1 was analyzed by chromatin immunoprecipitation (ChIP). The expression and translocation of NF-κB to the nucleus were detected by western blot analysis and immunofluorescence staining, respectively. An ovariectomized (OVX) osteoporosis mouse model was established to further confirm the in vitro findings.

Results

BMSC-derived EVs of osteoporotic patients exhibited downregulated miR-29b-3p. EV-encapsulated miR-29b-3p from BMSCs potentiated osteogenic differentiation by specifically inhibiting KDM5A. KDM5A inhibited osteogenic differentiation by the regulation of H3K4me3 and H3K27ac of SOCS1. SOCS1 potentiated osteogenic differentiation by inhibiting NF-κB pathway.

Conclusion

EV-encapsulated miR-29b-3p derived from BMSCs potentiated osteogenic differentiation through blockade of the SOCS1/NF-κB pathway by inhibition of KDM5A.

Extracellular vesicles in bone and periodontal regeneration: current and potential therapeutic applications

Oral mesenchymal stem cells (MSCs) and their secretomes are considered important factors in the field of medical tissue engineering and cell free biotherapy due to their ease of access, differentiation potential, and successful therapeutic outcomes. Extracellular vesicles (EVs) and the conditioned medium (CM) from MSCs are gaining more attraction as an alternative to cell-based therapies due to the less ethical issues involved, and their easier acquisition, preservation, long term storage, sterilization, and packaging. Bone and periodontal regenerative ability of EVs and CM have been the focus of some recent studies. In this review, we looked through currently available literature regarding MSCs' EVs or conditioned medium and their general characteristics, function, and regenerative potentials. We will also review the novel applications in regenerating bone and periodontal defects.

Molecular Mechanisms and Emerging Therapeutics for Osteoporosis

Osteoporosis is the most common chronic metabolic bone disease. It has been estimated that more than 10 million people in the United States and 200 million men and women worldwide have osteoporosis. Given that the aging population is rapidly increasing in many countries, osteoporosis could become a global challenge with an impact on the quality of life of the affected individuals. Osteoporosis can be defined as a condition characterized by low bone density and increased risk of fractures due to the deterioration of the bone architecture. Thus, the major goal of treatment is to reduce the risk for fractures. There are several treatment options, mostly medications that can control disease progression in risk groups, such as postmenopausal women and elderly men. Recent studies on the basic molecular mechanisms and clinical implications of osteoporosis have identified novel therapeutic targets. Emerging therapies targeting novel disease mechanisms could provide powerful approaches for osteoporosis management in the future. Here, we review the etiology of osteoporosis and the molecular mechanism of bone remodeling, present current pharmacological options, and discuss emerging therapies targeting novel mechanisms, investigational treatments, and new promising therapeutic approaches.

Immunomodulatory and Therapeutic Effects of Mesenchymal Stem Cells on Organ Dysfunction in Sepsis

ABSTRACT

Sepsis is a life-threatening disorder that is caused by a dysregulated inflammatory response during an infection. The disease mostly affects pregnant women, newborns, and patients in intensive care units. Sepsis treatment is a significant part of a country's health budgets. Delay in the therapy causes irreversible failure of various organs due to the lack of blood supply and reduction of oxygen in the tissues and eventually increased mortality. The involvement of four or five organs by sepsis has been attributed to an increased risk of death to over 90%. Although antibiotics are at the first line of sepsis treatment, they do not possess enough potency to control the disease and prevent subsequent organ failure. The immunomodulatory, anti-inflammatory, anti-apoptotic, and anti-microbial properties of mesenchymal stem cells (MSCs) have been reported in various studies. Therefore, the application of MSCs has been considered a potentially promising therapeutic strategy. In preclinical studies, the administration of MSCs has been associated with reduced bacterial load and decreased levels of pro-inflammatory factors as well as the improved function of the different vital organs, including heart, kidney, liver, and lungs. The current study provides a brief review of sepsis and its pathophysiology, and then highlights recent findings in the therapeutic effects of MSCs and MSC-derived secretome in improving sepsis-induced organ dysfunction. Besides, eligible sepsis candidates for MSC-therapy and the latest clinical findings in these areas have been reviewed.

The Delivery of Extracellular Vesicles Loaded in Biomaterial Scaffolds for Bone Regeneration

Extracellular vesicles (EVs) are heterogeneous nanoparticles actively released by cells that comprise highly conserved and efficient systems of intercellular communication. In recent years, numerous studies have proven that EVs play an important role in the field of bone tissue engineering (BTE) due to several advantages, such as good biosafety, stability and efficient delivery. However, the application of EVs therapies in bone regeneration has not been widely used. One of the major challenges for the application of EVs is the lack of sufficient scaffolds to load and control the release of EVs. Thus, in this review, we describe the most advanced current strategies for delivering EVs with various biomaterials for the use in bone regeneration, the role of EVs in bone regeneration, the distribution of EVs mediated by biomaterials and common methods of promoting EVs delivery efficacy with a focus on biomaterial properties.

Prospect of Stem Cell Therapy and Regenerative Medicine in Osteoporosis

The field of cell therapy and regenerative medicine can hold the promise of restoring normal tissues structure and function. Additionally, the main targets of stem cell-based therapies are chronic diseases and lifelong disabilities without definite cures such as osteoporosis. Osteoporosis as one of the important causes of morbidity in older men and post-menopausal women is characterized by reduced bone quantity or skeletal tissue atrophy that leads to an increased risk of osteoporotic fractures. The common therapeutic methods for osteoporosis only can prevent the loss of bone mass and recover the bone partially. Nevertheless, stem cell-based therapy is considered as a new approach to regenerate the bone tissue. Herein, mesenchymal stem cells as pivotal candidates for regenerative medicine purposes especially bone regeneration are the most common type of cells with anti-inflammatory, immune-privileged potential, and less ethical concerns than other types of stem cells which are investigated in osteoporosis. Based on several findings, the mesenchymal stem cells effectiveness near to a great extent depends on their secretory function. Indeed, they can be involved in the establishment of normal bone remodeling via initiation of specific molecular signaling pathways. Accordingly, the aim herein was to review the effects of stem cell-based therapies in osteoporosis.

Current and future uses of skeletal stem cells for bone regeneration

The postnatal skeleton undergoes growth, modeling, and remodeling. The human skeleton is a composite of diverse tissue types, including bone, cartilage, fat, fibroblasts, nerves, blood vessels, and hematopoietic cells. Fracture nonunion and bone defects are among the most challenging clinical problems in orthopedic trauma. The incidence of nonunion or bone defects following fractures is increasing. Stem and progenitor cells mediate homeostasis and regeneration in postnatal tissue, including bone tissue. As multipotent stem cells, skeletal stem cells (SSCs) have a strong effect on the growth, differentiation, and repair of bone regeneration. In recent years, a number of important studies have characterized the hierarchy, differential potential, and bone formation of SSCs. Here, we describe studies on and applications of SSCs and/or mesenchymal stem cells for bone regeneration.

Functional Relationship between Osteogenesis and Angiogenesis in Tissue Regeneration

Bone tissue renewal can be outlined as a complicated mechanism centered on the interaction between osteogenic and angiogenic events capable of leading to bone formation and tissue renovation. The achievement or debacle of bone regeneration is focused on the primary role of vascularization occurrence; in particular, the turning point is the opportunity to vascularize the bulk scaffolds, in order to deliver enough nutrients, growth factors, minerals and oxygen for tissue restoration. The optimal scaffolds should ensure the development of vascular networks to warrant a positive suitable microenvironment for tissue engineering and renewal. Vascular Endothelial Growth Factor (VEGF), a main player in angiogenesis, is capable of provoking the migration and proliferation of endothelial cells and indirectly stimulating osteogenesis, through the regulation of the osteogenic growth factors released and through paracrine signaling. For this reason, we concentrated our attention on two principal groups involved in the renewal of bone tissue defects: the cells and the scaffold that should guarantee an effective vascularization process. The application of Mesenchymal Stem Cells (MSCs), an excellent cell source for tissue restoration, evidences a crucial role in tissue engineering and bone development strategies. This review aims to provide an overview of the intimate connection between blood vessels and bone formation that appear during bone regeneration when MSCs, their secretome-Extracellular Vesicles (EVs) and microRNAs (miRNAs) -and bone substitutes are used in combination.

The Role of Tantalum Nanoparticles in Bone Regeneration Involves the BMP2/Smad4/Runx2 Signaling Pathway

Background

In recent years, nanomaterials have been increasingly developed and applied in the field of bone tissue engineering. However, there are few studies on the induction of bone regeneration by tantalum nanoparticles (Ta NPs) and no reports on the effects of Ta NPs on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and the underlying mechanisms. The main purpose of this study was to investigate the effects of Ta NPs on bone regeneration and BMSC osteogenic differentiation and the underlying mechanisms.

Materials and Methods

The effects of Ta NPs on bone regeneration were evaluated in an animal experiment, and the effects of Ta NPs on osteogenic differentiation of BMSCs and the underlying mechanisms were evaluated in cell experiments. In the animal experiment, hematoxylin-eosin (HE) staining and hard-tissue section analysis showed that Ta NPs promoted bone regeneration, and immunohistochemistry revealed elevated expression of BMP2 and Smad4 in cells cultured with Ta NPs.

Results

The results of the cell experiments showed that Ta NPs promoted BMSC proliferation, alkaline phosphatase (ALP) activity, BMP2 secretion and extracellular matrix (ECM) mineralization, and the expression of related osteogenic genes and proteins (especially BMP2, Smad4 and Runx2) was upregulated under culture with Ta NPs. Smad4 expression, ALP activity, ECM mineralization, and osteogenesis-related gene and protein expression decreased after inhibiting Smad4.

Conclusion

These data suggest that Ta NPs have an osteogenic effect and induce bone regeneration by activating the BMP2/Smad4/Runx2 signaling pathway, which in turn causes BMSCs to undergo osteogenic differentiation. This study provides insight into the molecular mechanisms underlying the effects of Ta NPs in bone regeneration.

Pharmacotherapy to gene editing: potential therapeutic approaches for Hutchinson-Gilford progeria syndrome

Hutchinson-Gilford progeria syndrome (HGPS), commonly called progeria, is an extremely rare disorder that affects only one child per four million births. It is characterized by accelerated aging in affected individuals leading to premature death at an average age of 14.5 years due to cardiovascular complications. The main cause of HGPS is a sporadic autosomal dominant point mutation in LMNA gene resulting in differently spliced lamin A protein known as progerin. Accumulation of progerin under nuclear lamina and activation of its downstream effectors cause perturbation in cellular morphology and physiology which leads to a systemic disorder that mainly impairs the cardiovascular system, bones, skin, and overall growth. Till now, no cure has been found for this catastrophic disorder; however, several therapeutic strategies are under development. The current review focuses on the overall progress in the field of therapeutic approaches for the management/cure of HGPS. We have also discussed the new disease models that have been developed for the study of this rare disorder. Moreover, we have highlighted the therapeutic application of extracellular vesicles derived from stem cells against aging and aging-related disorders and, therefore, suggest the same for the treatment of HGPS.

Enhancement of osteoblast cells osteogenic differentiation and bone regeneration by hydroxyapatite/phosphoester modified poly(amino acid)

Hydroxyapatite/poly(amino acid) (HA/PAA) has been used to treat a variety of long bone and vertebral bony defects, and a further biocompatibility improvement is a key for better application. Phosphoester (PE) contained materials are highly biocompatible but could hardly treat massive bone defects due to its fast-degradation-derived mechanical instability. To address the problems of the two materials, we have incorporated PE molecule into the main chain of PAA by chemical bonding. As a result, the compressive strength of HA/PAA with 1 wt% and 2.5 wt% PE maintained in the range of 80-150 MPa after soaking in PBS for 12 weeks, which could be attributed to the amplified hydrogen-bonding inside composites. Besides, the PE-containing HA/PAAs with increased hydrophilic function groups (O=P-O bonds and O=P-N), created a more favourable surface for cell adhesion. Meanwhile, compared with HA/PAA, the PE-containing HA/PAAs had a fast minerlization speed and promoted cell osteogenic differentiation. Furthermore, the in vivo study indicated that PE-containing HA/PAAs could facilitate bone formation (4 weeks), and form a complete bone bridging (12 weeks) in a rabbit cranial bone defect. In summary, the HA/PE-m-PAAs possessed good mechanical stability, improved cytocompatibility and osteoconductivity, so the composites have a great potential for massive bone defect treatment.

Novel ultrafine-grained β-type Ti-28Nb-2Zr-8Sn alloy for biomedical applications

Titanium alloys are widely accepted as orthopedic or dental implant materials in the medical field. It is important to evaluate the biocompatibility of an implant material prior to use. A new β-type ultrafine-grained Ti-28Nb-2Zr-8Sn (TNZS) alloy with low Young's modulus of 31.6 GPa was fabricated. This study aims to evaluate the biocompatibility of TNZS alloy. In this study, we examined the microstructure, chemical composition and surface wettability of the TNZS alloy. The mouse embryonic osteoblast MC3T3-E1 cells and human umbilical vein endothelial cells (HUVECs) were cultured to study the cytocompatibility of TNZS alloy. Also, we evaluated the proinflammatory response of TNZS alloy in vitro and in vivo. The results show that the TNZS did not cause cytotoxicity, genotoxicity to MC3T3-E1 cells and HUVECs. Whereas, the TNZS alloy could significantly promote the cell proliferation, cell spreading and cell adhesion of MC3T3-E1 cells and HUVECs, as well as facilitate the osteogenic differentiation of MC3T3-E1 cells. Moreover, the TNZS alloy did not induce any remarkable proinflammatory response in vitro and in vivo. Thus, the novel TNZS alloy with an elasticity closer to that of human bone is biologically safe and could be a potential candidate for biomedical implant application. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1628-1639, 2019.