Emerging Potential of Exosomes in Regenerative Medicine for Temporomandibular Joint Osteoarthritis

Exosomes of stem cells: a potential frontier in the treatment of osteoarthritis

The aging population has led to a global issue of osteoarthritis (OA), which not only impacts the quality of life for patients but also poses a significant economic burden on society. While biotherapy offers hope for OA treatment, currently available treatments are unable to delay or prevent the onset or progression of OA. Recent studies have shown that as nanoscale bioactive substances that mediate cell communication, exosomes from stem cell sources have led to some breakthroughs in the treatment of OA and have important clinical significance. This paper summarizes the mechanism and function of stem cell exosomes in delaying OA and looks forward to the development prospects and challenges of exosomes.

Fostamatinib alleviates temporomandibular joint osteoarthritis by maintaining cartilage homeostasis through MAPK/NF-κB and AKT/mTOR pathways

Temporomandibular joint osteoarthritis (TMJ OA) is a common degenerative disease characterized by cartilage degeneration. However, the therapeutic strategies aimed to maintain cartilage homeostasis remain unclear. Fostamatinib (Fos) is a potential clinical drug for rheumatoid arthritis (RA) and predicted as target drug for many inflammatory diseases. In this study we investigated the therapeutic effects of Fos for TMJ OA and underlying mechanisms. Interleukin-1β (IL-1β) was used to construct a condylar chondrocyte injury model in vitro and rat TMJ OA models were induced by unilateral anterior crossbite (UAC) in vivo. Subsequently, a series of experiments were performed to assess the therapeutic effects and potential mechanisms of Fos in TMJ OA. Herein, we verified that Fos improved IL-1β-induced decrease in chondrocyte viability and proliferation, as well as inhibited cell apoptosis. Additionally, Fos could alleviate IL-1β-induced inflammation, ECM degradation, and chondrocyte phenotype change through blocking MAPK/NF-κB pathways, as well as promote chondrocyte autophagy by regulating AKT/mTOR pathways. The therapeutic effects of Fos on TMJ OA were further validated through rat UAC model in vivo. Overall, Fos could maintaining cartilage homeostasis through regulating chondrocyte inflammation, ECM degradation, and abnormal cell biological behaviors (apoptosis and autophagy), which made it a promising small molecule drug for TMJ OA early intervention.

Cartilage Tissue Engineering in Multilayer Tissue Regeneration

The functional and structural integrity of the tissue/organ can be compromised in multilayer reconstructive applications involving cartilage tissue. Therefore, multilayer structures are needed for cartilage applications. In this review, we have examined multilayer scaffolds for use in the treatment of damage to organs such as the trachea, joint, nose, and ear, including the multilayer cartilage structure, but we have generally seen that they have potential applications in trachea and joint regeneration. In conclusion, when the existing studies are examined, the results are promising for the trachea and joint connections, but are still limited for the nasal and ear. It may have promising implications in the future in terms of reducing the invasiveness of existing grafting techniques used in the reconstruction of tissues with multilayered layers.

The Role of Gli1+ Mesenchymal Stem Cells in Craniofacial Development and Disease Treatment

OBJECTIVE

This review summarises the role of Gli1+ (Glioma-associated oncogene homologue 1) mesenchymal stem cells in craniofacial growth and development or tissue repair, and their application in the treatment of some diseases.

DESIGN

The search for this narrative review was conducted in PubMed and Web of Science using relevant keywords, including checking reference lists of journal articles by hand searching.

RESULTS

Gli1+ mesenchymal stem cells play an important role in the growth and development of the skull, tooth, periodontium and mandibular condyle. They can be applied to the treatment of pulp and periodontal diseases, temporomandibular joint osteoarthritis and other diseases.

CONCLUSIONS

Gli1+ mesenchymal stem cells are crucial for the development and repair of craniofacial tissue.

A new strategy for drug delivery systems in oral diseases using stem cell-derived extracellular vesicles: review and new perspectives

Extracellular vesicles (EVs) are membrane vesicles derived from cells and serve as an endogenous mechanism for intercellular communication. Since the discovery of their capacity to effectively transfer biological information, their potential as drug delivery vehicles has garnered significant scientific interest. Particularly, EVs derived from mesenchymal cells (MSC-EVs) have emerged as a highly promising method for drug delivery. They can transport bioactive molecules, such as nucleic acids, lipids, and proteins, and possess the ability to modulate immune responses, transmit information, and target specific cells. EVs offer several advantages over conventional drug delivery systems, including their capacity to traverse natural barriers, inherent cell targeting capabilities, and stability in circulation. Compared to their parent cells, EVs exhibit low immunogenicity, ease of storage and transport, and a reduced risk of tumorigenesis. The diagnosis and treatment of oral diseases often involve invasive measures, and MSC-EVs have demonstrated initial efficacy in oral disease treatment. This review explores the application of MSC-EVs in maxillofacial tissue regeneration, periodontitis, temporomandibular joint osteoarthritis, Sjögren's Syndrome, oral cancer, and other oral diseases. Additionally, it outlines potential future directions for the development of MSC-EVs. This review aims to provide a comprehensive understanding of MSC-EVs in oral disease treatment and to stimulate interest in their applications for targeted drug delivery.

Controlled Release of Human Dental Pulp Stem Cell-Derived Exosomes from Hydrogels Attenuates Temporomandibular Joint Osteoarthritis

Temporomandibular joint osteoarthritis (TMJOA) is a painful inflammatory condition that limits mouth opening. Cell-derived exosomes, which have anti-inflammatory effects, are emerging as a treatment for TMJOA. Injection of dental pulp stem cells (DPSCs), which secrete exosomes, can moderate tissue damage in a rat model of TMJOA. However, injected exosomes are quickly cleared, necessitating repeated injections for therapeutic efficacy. Here, vinyl sulfone-modified hyaluronic acid (HA-VS) hydrogels, suitable for encapsulating exosomes are formulated. HA-VS hydrogels degrade in the presence of hyaluronidase and allow for the release of beads of similar size to exosomes over 3 to 6 days. In a rat model of TMJOA, injection of exosomes or exosomes within HA-VS hydrogels significantly attenuated damage-mediated subchondral bone loss as determined by micro-computed tomography, and reduced inflammatory and tissue damage scores as assessed by histology. Overall, DPSCs-derived exosomes attenuated joint damage, but treatment with exosomes within HA-VS hydrogels shows additional protective effects on subchondral bone maintenance and integrity. These findings confirm the protective effects of DPSCs-derived exosomes in moderating tissue damage in TMJOA and suggest that combining exosomes with HA hydrogels can further promote their therapeutic effects.

Extracellular Vesicles: A Novel Diagnostic Tool and Potential Therapeutic Approach for Equine Osteoarthritis

Osteoarthritis (OA) is a chronic progressive degenerative joint disease that affects a significant portion of the equine population and humans worldwide. Current treatment options for equine OA are limited and incompletely curative. Horses provide an excellent large-animal model for studying human OA. Recent advances in the field of regenerative medicine have led to the exploration of extracellular vesicles (EVs)-cargoes of microRNA, proteins, lipids, and nucleic acids-to evaluate their diagnostic value in terms of disease progression and severity, as well as a potential cell-free therapeutic approach for equine OA. EVs transmit molecular signals that influence various biological processes, including the inflammatory response, apoptosis, proliferation, and cell communication. In the present review, we summarize recent advances in the isolation and identification of EVs, the use of their biologically active components as biomarkers, and the distribution of the gap junction protein connexin 43. Moreover, we highlight the role of mesenchymal stem cell-derived EVs as a potential therapeutic tool for equine musculoskeletal disorders. This review aims to provide a comprehensive overview of the current understanding of the pathogenesis, diagnosis, and treatment strategies for OA. In particular, the roles of EVs as biomarkers in synovial fluid, chondrocytes, and plasma for the early detection of equine OA are discussed.

Extracellular vesicles as therapeutic tools in regenerative dentistry

Dental and maxillofacial diseases are always accompanied by complicated hard and soft tissue defects, involving bone, teeth, blood vessels and nerves, which are difficult to repair and severely affect the life quality of patients. Recently, extracellular vesicles (EVs) secreted by all types of cells and extracted from body fluids have gained more attention as potential solutions for tissue regeneration due to their special physiological characteristics and intrinsic signaling molecules. Compared to stem cells, EVs present lower immunogenicity and tumorigenicity, cause fewer ethical problems, and have higher stability. Thus, EV therapy may have a broad clinical application in regenerative dentistry. Herein, we reviewed the currently available literature regarding the functional roles of EVs in oral and maxillofacial tissue regeneration, including in maxilla and mandible bone, periodontal tissues, temporomandibular joint cartilage, dental hard tissues, peripheral nerves and soft tissues. We also summarized the underlying mechanisms of actions of EVs and their delivery strategies for dental tissue regeneration. This review would provide helpful guidelines and valuable insights into the emerging potential of EVs in future research and clinical applications in regenerative dentistry.

The Interplay of Mitochondrial Dysfunction in Oral Diseases: Recent Updates in Pathogenesis and Therapeutic Implications

Mitochondrial dysfunction is linked to various systemic and localized diseases, including oral diseases like periodontitis, oral cancer, and temporomandibular joint disorders. This paper explores the intricate mechanisms underlying mitochondrial dysfunction in oral pathologies, encompassing oxidative stress, inflammation, and impaired energy metabolism. Furthermore, it elucidates the bidirectional relationship between mitochondrial dysfunction and oral diseases, wherein the compromised mitochondrial function exacerbates disease progression, while oral pathologies, in turn, exacerbate mitochondrial dysfunction. Understanding these intricate interactions offers insights into novel therapeutic strategies targeting mitochondrial function for managing oral diseases. This paper pertains to the mechanisms underlying mitochondrial dysfunction, its implications in various oral pathological and inflammatory conditions, and emerging versatile treatment approaches. It reviews current therapeutic strategies to mitigate mitochondrial dysfunction, including antioxidants, mitochondrial-targeted agents, and metabolic modulators.

Mesenchymal Stem Cell-Derived Exosomes as a Treatment Option for Osteoarthritis

Osteoarthritis (OA) is a leading cause of pain and disability worldwide in elderly people. There is a critical need to develop novel therapeutic strategies that can effectively manage pain and disability to improve the quality of life for older people. Mesenchymal stem cells (MSCs) have emerged as a promising cell-based therapy for age-related disorders due to their multilineage differentiation and strong paracrine effects. Notably, MSC-derived exosomes (MSC-Exos) have gained significant attention because they can recapitulate MSCs into therapeutic benefits without causing any associated risks compared with direct cell transplantation. These exosomes help in the transport of bioactive molecules such as proteins, lipids, and nucleic acids, which can influence various cellular processes related to tissue repair, regeneration, and immune regulation. In this review, we have provided an overview of MSC-Exos as a considerable treatment option for osteoarthritis. This review will go over the underlying mechanisms by which MSC-Exos may alleviate the pathological hallmarks of OA, such as cartilage degradation, synovial inflammation, and subchondral bone changes. Furthermore, we have summarized the current preclinical evidence and highlighted promising results from in vitro and in vivo studies, as well as progress in clinical trials using MSC-Exos to treat OA.

The Role of Extracellular Vesicles in Bone Regeneration and Associated Bone Diseases

Extracellular vesicles (EVs) are nanoscale particles with a lipid bilayer membrane structure secreted by various cell types. Nearly all human cells secrete EVs, primarily mediating intercellular communication. In recent years, scientists have discovered that EVs can carry multiple biological cargos, such as DNA, non-coding RNAs (ncRNAs), proteins, cytokines, and lipids, and mediate intercellular signal transduction. Bone is a connective tissue with a nerve supply and high vascularization. The repair process after injury is highly complex, involving interactions among multiple cell types and biological signaling pathways. Bone regeneration consists of a series of coordinated osteoconductive and osteoinductive biological processes. As mediators of intercellular communication, EVs can promote bone regeneration by regulating osteoblast-mediated bone formation, osteoclast-mediated bone resorption, and other pathways. This review summarizes the biogenesis of EVs and the mechanisms by which EV-mediated intercellular communication promotes bone regeneration. Additionally, we focus on the research progress of EVs in various diseases related to bone regeneration. Finally, based on the above research, we explore the clinical applications of engineered EVs in the diagnosis and treatment of bone regeneration-related diseases.

Automatic prediction of obstructive sleep apnea in patients with temporomandibular disorder based on multidata and machine learning

Obstructive sleep apnea (OSA) is closely associated with the development and chronicity of temporomandibular disorder (TMD). Given the intricate pathophysiology of both OSA and TMD, comprehensive diagnostic approaches are crucial. This study aimed to develop an automatic prediction model utilizing multimodal data to diagnose OSA among TMD patients. We collected a range of multimodal data, including clinical characteristics, portable polysomnography, X-ray, and MRI data, from 55 TMD patients who reported sleep problems. This data was then analyzed using advanced machine learning techniques. Three-dimensional VGG16 and logistic regression models were used to identify significant predictors. Approximately 53% (29 out of 55) of TMD patients had OSA. Performance accuracy was evaluated using logistic regression, multilayer perceptron, and area under the curve (AUC) scores. OSA prediction accuracy in TMD patients was 80.00-91.43%. When MRI data were added to the algorithm, the AUC score increased to 1.00, indicating excellent capability. Only the obstructive apnea index was statistically significant in predicting OSA in TMD patients, with a threshold of 4.25 events/h. The learned features of the convolutional neural network were visualized as a heatmap using a gradient-weighted class activation mapping algorithm, revealing that it focuses on differential anatomical parameters depending on the absence or presence of OSA. In OSA-positive cases, the nasopharynx, oropharynx, uvula, larynx, epiglottis, and brain region were recognized, whereas in OSA-negative cases, the tongue, nose, nasal turbinate, and hyoid bone were recognized. Prediction accuracy and heat map analyses support the plausibility and usefulness of this artificial intelligence-based OSA diagnosis and prediction model in TMD patients, providing a deeper understanding of regions distinguishing between OSA and non-OSA.

Therapeutic Effects of PEG-Modified Polyamide Amine Dendrimer for Cell Free DNA Adsorption in Temporomandibular Joint Osteoarthritis

Temporomandibular joint osteoarthritis (TMJ OA) is characterized by the degeneration of cartilage and subchondral bone. In this study, we observed a significant increase in cell-free DNA (cfDNA) levels during the progression of TMJ OA. Bioinformatics analysis identified TLR9 as a pivotal molecule in TMJ OA pathogenesis. The polyamidoamine (PAMAM) dendrimer characterized by a well-structured, highly branched, and reactive nature, exhibits robust binding and clearance capabilities for cfDNA. However, the abundant amino groups on the surface of PAMAM lead to its inherent toxicity. To mitigate this, PEG-5000 was conjugated to the surface of PAMAM dendrimers, enhancing safety. Our results indicate that PEG-PAMAM effectively inhibits the upregulation of the TLR9 protein in TMJ OA, significantly suppressing the activation of the p-IκBα/p-NF-κB signaling pathway and subsequently decreasing chondrocyte inflammation and apoptosis, as evidenced by both in vivo and in vitro experiments. We conclude that PEG-PAMAM is a safe and effective material for in vivo applications, offering a promising therapeutic strategy for TMJ OA by targeting cfDNA clearance.

Significance of radiographic temporomandibular degenerative joint disease findings

The field of orthodontics has seen a recent increase in the number of patients over the age of 50 seeking treatment and also an increase in the use of cone beam technology. Similar to other joints in the body, the temporomandibular joint (TMJ) is associated with age-related degeneration. However, unlike other joints, degeneration of the TMJ is rarely symptomatic and when there is pain, it is usually self-limiting. In this article, we will review: a) the incidence and prevalence of TMJ degenerative diseases, b) similarities and differences of TMJ vs knee degenerative diseases, and c) current treatment recommendations for TMJ degenerative diseases. In the vast majority of people, radiographic evidence of TMJ degeneration is an incidental finding. Future longitudinal research is needed to follow the natural course of TMJ degenerative patients.

Autologous Fat Transfer in Craniofacial Surgery

Over the past two decades, autologous fat transfer has garnered significant recognition and widespread adoption within esthetic and reconstructive surgical domains. In craniofacial surgery, fat transplantation is frequently employed to address soft tissue volumetric deficiencies and asymmetries that influence facial contours. While adipose tissue (AT) is widely regarded as an optimal choice for augmentation due to its abundant availability and biocompatibility, the unpredictability and heightened resorption rates observed with traditional lipofilling techniques present a challenge for clinicians. Adipose-derived stem cells (ASCs) housed within the grafted tissue play a pivotal role in graft survival and offer avenues for tissue repair due to their angiogenic, anti-inflammatory, and immunosuppressive properties. Micro Fragmentation of Adipose Tissue (MFAT), utilized in several FDA-approved processing devices, has demonstrated promising outcomes in treating osteoarthritic joints, with success primarily attributed to enhanced paracrine function of ASCs via preservation of the perivascular niche. Currently, its application for treating bone or articular defects in the craniofacial region, including abnormalities of the temporomandibular joint, remains limited. This scarcity underscores the need for further investigation prior to its widespread integration into clinical practice.

M1 macrophage-derived exosomes promote intervertebral disc degeneration by enhancing nucleus pulposus cell senescence through LCN2/NF-κB signaling axis

Intervertebral disc degeneration (IVDD) is the primary factor contributing to low back pain (LBP). Unlike elderly patients, many young IVDD patients usually have a history of trauma or long-term abnormal stress, which may lead to local inflammatory reaction causing by immune cells, and ultimately accelerates degeneration. Research has shown the significance of M1-type macrophages in IVDD; nevertheless, the precise mechanism and the route by which it influences the function of nucleus pulposus cell (NPC) remain unknown. Utilizing a rat acupuncture IVDD model and an NPC degeneration model induced by lipopolysaccharide (LPS), we investigated the function of M1 macrophage-derived exosomes (M1-Exos) in IVDD both in vivo and in vitro in this study. We found that M1-Exos enhanced LPS-induced NPC senescence, increased the number of SA-β-gal-positive cells, blocked the cell cycle, and promoted the activation of P21 and P53. M1-Exos derived from supernatant pretreated with the exosome inhibitor GW4869 reversed this result in vivo and in vitro. RNA-seq showed that Lipocalin2 (LCN2) was enriched in M1-Exos and targeted the NF-κB pathway. The quantity of SA-β-gal-positive cells was significantly reduced with the inhibition of LCN2, and the expression of P21 and P53 in NPCs was decreased. The same results were obtained in the acupuncture-induced IVDD model. In addition, inhibition of LCN2 promotes the expression of type II collagen (Col-2) and inhibits the expression of matrix metalloproteinase 13 (MMP13), thereby restoring the equilibrium of metabolism inside the extracellular matrix (ECM) in vitro and in vivo. In addition, the NF-κB pathway is crucial for regulating M1-Exo-mediated NPC senescence. After the addition of M1-Exos to LPS-treated NPCs, p-p65 activity was significantly activated, while si-LCN2 treatment significantly inhibited p-p65 activity. Therefore, this paper demonstrates that M1 macrophage-derived exosomes have the ability to deliver LCN2, which activates the NF-κB signaling pathway, and exacerbates IVDD by accelerating NPC senescence. This may shed new light on the mechanism of IVDD and bring a fresh approach to IVDD therapy.

Climate temperature and seasonal influences on the prevalence of temporomandibular disorders in South Korea

This study aimed to explore seasonal variations in temporomandibular disorder (TMD) prevalence in South Korea, utilizing nationwide population-based big data. Data corresponding to the Korean Standard Classification of Diseases code of K07.6, which identifies TMD, were extracted from the Health Insurance Review and Assessment Service online platform for the period from 2010 to 2022. Additionally, we integrated these data with climate temperature records from the Korean Meteorological Administration. We subsequently conducted a statistical analysis of TMD patient data on a monthly and seasonal basis over the past 13 years to assess prevalence. Over the past 13 years, the number of TMD patients in Korea has steadily increased. The prevalence of TMD rose from 0.48% (224,708 out of a total population of 50,515,666) in 2010 to 0.94% (482,241 out of a total population of 51,439,038) in 2022, marking a 1.96-fold increase. Among children under 10 years of age, no significant differences were observed in TMD prevalence between boys and girls. However, a distinct female predominance emerged after the age of 10, with an average female-to-male ratio of 1.51:1. The peak prevalence of TMD occurred in individuals in their 20 s, followed by adolescents in their late 10 s. The majority of TMD patients were concentrated in Seoul and Gyeonggi province, with metropolitan areas accounting for 50% of the total patient count. Seasonally, TMD patient numbers showed no significant increase in winter compared with spring or summer. The temperature difference, defined as the absolute difference between the highest and lowest temperatures for each month, showed a positive correlation with TMD patient counts. A greater temperature difference was associated with higher patient counts. The strongest correlation between temperature differences and TMD patient numbers was observed in winter (r = 0.480, p < 0.01), followed by summer (r = 0.443, p < 0.01), and spring (r = 0.366, p < 0.05). Temperature differences demonstrated a significantly stronger correlation with the increase in the number of TMD patients than absolute climate temperatures. This aspect should be a key consideration when examining seasonal trends in TMD prevalence in South Korea.

Pleiotrophin inhibited chondrogenic differentiation potential of dental pulp stem cells

OBJECTIVE

Studies have shown that the levels of pleiotrophin (PTN) are greatly elevated in the synovial fluid and cartilage in osteoarthritis. Therefore, the purpose of this study was to investigate the effect and mechanism of PTN on the chondrogenic differentiation of DPSCs in inflammatory and normal microenvironments.

MATERIALS AND METHODS

A lentiviral vector was used to deplete or overexpress PTN in DPSCs. The inflammatory microenvironment was simulated in vitro by the addition of IL-1β to the culture medium. The chondrogenic differentiation potential was assessed using Alcian Blue staining and the main chondrogenic markers. A dual-luciferase reporter assay was used to explore the relationship between miR-137 and PTN.

RESULTS

The results showed that 0.1 ng/mL IL-1β treatment during chondrogenic induction greatly impaired the chondrogenic differentiation of DPSCs. Supplementation with PTN and PTN overexpression inhibited chondrogenic differentiation of DPSCs, while PTN depletion promoted chondrogenic differentiation. MiR-137 negatively regulated the expression of PTN by binding to the 3'UTR of its mRNA. Moreover, miR-137 promoted chondrogenic differentiation of DPSCs in normal and inflammatory microenvironments.

CONCLUSION

Our results suggest that PTN may play an inhibitory role in the chondrogenic differentiation of DPSCs in normal and inflammatory microenvironments, which is regulated by miR-137.

Mesenchymal stem cell-derived exosomes as a promising cell-free therapy for knee osteoarthritis

Osteoarthritis (OA), as a degenerative disease, leads to high socioeconomic burdens and disability rates. The knee joint is typically the most affected and is characterized by progressive destruction of articular cartilage, subchondral bone remodeling, osteophyte formation and synovial inflammation. The current management of OA mainly focuses on symptomatic relief and does not help to slow down the advancement of disease. Recently, mesenchymal stem cells (MSCs) and their exosomes have garnered significant attention in regenerative therapy and tissue engineering areas. Preclinical studies have demonstrated that MSC-derived exosomes (MSC-Exos), as bioactive factor carriers, have promising results in cell-free therapy of OA. This study reviewed the application of various MSC-Exos for the OA treatment, along with exploring the potential underlying mechanisms. Moreover, current strategies and future perspectives for the utilization of engineered MSC-Exos, alongside their associated challenges, were also discussed.

Anesthetic management of patients with difficult intubation due to temporomandibular joint osteoarthritis: A case report

INTRODUCTION

Temporomandibular joint osteoarthritis (TMJOA) affects 8% to 16% of the global population, yet TMJOA remains relatively underappreciated clinically. To anesthesiologists, who is concerned about patient safety, adequate preoperative evaluation and preparation, as well as individualized anesthetic management of patients, are necessary. Therefore, the anesthesiologist should be alert for difficult airways due to TMJOA, have a full and comprehensive understanding of the disease, and possess the appropriate expertise for difficult airway intubation.

CASE PRESENTATION

A 52-year-old female patient was scheduled for laparoscopic operation of uterine adnexa under general anesthesia. The patient preoperative evaluation showed only 1 finger width of mouth opening, and the computed tomography scan showed bilateral temporomandibular arthritis, which was evident on the right side. Intraoperatively, the expected airway difficulties occurred, and the anesthesiologist opted to use lightwand intubation, which was ultimately successful in 1 pass without any complications.

CONCLUSION

Intubation using a lightwand for patients with difficult intubation due to TMJOA is a very effective intubation modality.

Different Sources of Bone Marrow Mesenchymal Stem Cells: A Comparison of Subchondral, Mandibular, and Tibia Bone-derived Mesenchymal Stem Cells

BACKGROUND

Stem cell properties vary considerably based on the source and tissue site of mesenchymal stem cells (MSCs). The mandibular condyle is a unique kind of craniofacial bone with a special structure and a relatively high remodeling rate. MSCs here may also be unique to address specific physical needs.

OBJECTIVE

The aim of this study was to compare the proliferation and multidirectional differentiation potential among MSCs derived from the tibia (TMSCs), mandibular ramus marrow (MMSCs), and condylar subchondral bone (SMSCs) of rats in vitro.

METHODS

Cell proliferation and migration were assessed by CCK-8, laser confocal, and cell scratch assays. Histochemical staining and real-time PCR were used to evaluate the multidirectional differentiation potential and DNA methylation and histone deacetylation levels.

RESULTS

The proliferation rate and self-renewal capacity of SMSCs were significantly higher than those of MMSCs and TMSCs. Moreover, SMSCs possessed significantly higher mineralization and osteogenic differentiation potential. Dnmt2, Dnmt3b, Hdac6, Hdac7, Hdac9, and Hdac10 may be instrumental in the osteogenesis of SMSCs. In addition, SMSCs are distinct from MMSCs and TMSCs with lower adipogenic differentiation and chondrogenic differentiation potential. The multidirectional differentiation capacities of TMSCs were exactly the opposite of those of SMSCs, and the results of MMSCs were intermediate.

CONCLUSION

This research offers a new paradigm in which SMSCs could be a useful source of stem cells for further application in stem cell-based medical therapies due to their strong cell renewal and osteogenic capacity.

Stem Cell-Derived Extracellular Vesicles for Cancer Therapy and Tissue Engineering Applications

Recently, stem cells and their secretomes have attracted great attention in biomedical applications, particularly extracellular vesicles (EVs). EVs are secretomes of cells for cell-to-cell communication. They play a role as intercellular messengers as they carry proteins, nucleic acids, lipids, and therapeutic agents. They have also been utilized as drug-delivery vehicles due to their biocompatibility, low immunogenicity, stability, targetability, and engineerable properties. The therapeutic potential of EVs can be further enhanced by surface engineering and modification using functional molecules such as aptamers, peptides, and antibodies. As a consequence, EVs hold great promise as effective delivery vehicles for enhancing treatment efficacy while avoiding side effects. Among various cell types that secrete EVs, stem cells are ideal sources of EVs because stem cells have unique properties such as self-renewal and regenerative potential for transplantation into damaged tissues that can facilitate their regeneration. However, challenges such as immune rejection and ethical considerations remain significant hurdles. Stem cell-derived EVs have been extensively explored as a cell-free approach that bypasses many challenges associated with cell-based therapy in cancer therapy and tissue regeneration. In this review, we summarize and discuss the current knowledge of various types of stem cells as a source of EVs, their engineering, and applications of EVs, focusing on cancer therapy and tissue engineering.

Human Dental Follicle Cell-Derived Small Extracellular Vesicles Attenuate Temporomandibular Joint Cartilage Damage through Inhibiting HIF-2α

Mesenchymal stem cell (MSC)-based therapies for articular cartilage regeneration are effective mostly due to paracrine signals mediated by extracellular vesicles, especially small extracellular vesicles (sEV). However, it is unknown whether dental follicle cell-derived sEV (DFC-sEV) affect cartilage regeneration in temporomandibular joint osteoarthritis (TMJ-OA). In this study, the effects of DFC-sEV on IL-1β-induced mandibular condylar chondrocytes (MCCs) were determined using CCK8 assays, scratch assays, flow cytometry, and Western blot analysis of matrix synthesis and catabolic proteins. Furthermore, we used an abnormal occlusion-induced rat model and intra-articular injection of DFC-sEV, the pathological changes of which were observed by HE staining, safranin O staining, immunohistochemistry, and micro-CT analysis of subchondral bone loss. Gene set enrichment analysis (GSEA) was used to determine the related mechanism involved in the effect of DFC-sEV. Immunofluorescence analysis and Western blotting were used to evaluate the expression of HIF-1α, HIF-2α, MMP13, and VEGF in MCCs. Then, lentivirus-induced Epas1 overexpression and Western blot analysis of the downstream regulators of HIF-2α were performed. We found that DFC-sEV promoted MCCs proliferation and migration and protected against cartilage matrix destruction induced by IL-1β. In addition, DFC-sEV prevented cartilage destruction in an abnormal occlusion rat model. Furthermore, we found that DFC-sEV reduced the expression of HIF-1α and HIF-2α in vitro and in vivo and decreased the downstream regulators of HIF-2α, including MMP13 and VEGF. Our study indicated that DFC-sEV attenuated TMJ cartilage damage in vitro and in vivo, which might be involved in the regulation of HIF-2α.

IL-38 suppresses macrophage M1 polarization to ameliorate synovial inflammation in the TMJ via GLUT-1 inhibition

OBJECTIVES

Interleukin (IL)-38 was discovered as an anti-inflammatory factor. However, IL-38's role in M1 macrophage polarization in the temporomandibular joint (TMJ) and the related mechanism are still unclear. We aimed to explore the effect and the mechanism of IL-38 on synovial inflammation in the TMJ in this study.

METHODS

The expression of IL-38 in the TMJ synovium and macrophages was determined using immunohistochemistry (IHC) and Western blotting (WB). M1 macrophage polarization was induced by LPS, the macrophages were pre-treated with IL-38, and the levels of inflammatory markers associated with M1 macrophages were measured. To assess the mechanism of IL-38, small-interfering RNA (siRNA)-GLUT-1 and STF31 were administered to macrophages, and the affected pathways were identified by WB. The effect of macrophage-conditioned medium (CM) on chondrocyte function was also determined. Finally, a mouse model of CFA-induced TMJ inflammation was established. Histological staining and IHC were used to determine the effect of IL-38.

RESULTS

IL-38 was detected at high levels in macrophages after lipopolysaccharide (LPS)challenge, and IL-38 downregulated M1 macrophage-related proinflammatory markers (iNOS, IL-6, TNF-α, and COX-2) in vitro. IL-38 suppressed M1 polarization by inhibiting GLUT-1 expression, NF-κB signaling, and MAPK signaling. Intriguingly, CM from macrophages that were pretreated with IL-38 and STF31 decreased inflammatory protein expression in chondrocytes. In addition, intra-articular injection of recombinant IL-38 ameliorated synovial inflammation in the TMJ by inhibiting M1 macrophage polarization and suppressing cartilage inflammation in vivo.

CONCLUSIONS

IL-38 is a novel anti-inflammatory factor that contributes to alleviating TMJ inflammation by inhibiting macrophage M1 polarization, thereby ameliorating chondrocyte inflammation and restoring TMJ homeostasis.

Research Progress on Nanomaterials for Tissue Engineering in Oral Diseases

Due to their superior antibacterial properties, biocompatibility and high conductivity, nanomaterials have shown a broad prospect in the biomedical field and have been widely used in the prevention and treatment of oral diseases. Also due to their small particle sizes and biodegradability, nanomaterials can provide solutions for tissue engineering, especially for oral tissue rehabilitation and regeneration. At present, research on nanomaterials in the field of dentistry focuses on the biological effects of various types of nanomaterials on different oral diseases and tissue engineering applications. In the current review, we have summarized the biological effects of nanoparticles on oral diseases, their potential action mechanisms and influencing factors. We have focused on the opportunities and challenges to various nanomaterial therapy strategies, with specific emphasis on overcoming the challenges through the development of biocompatible and smart nanomaterials. This review will provide references for potential clinical applications of novel nanomaterials in the field of oral medicine for the prevention, diagnosis and treatment of oral diseases.

Mesenchymal-Stem Cell-Derived Conditioned Media Versus Exosomes in the Treatment of Rat Model of Polycystic Ovary: An Attempt to Understand the Underlying Mechanisms (Biochemical and Histological Study)

Polycystic ovary syndrome (PCOS) is one of the most common endocrine and reproductive disorders throughout female reproductive age. Cell free therapy [conditioned media (CM) & exosomes (EXO)] is a promising approach in regenerative medicine. This study aimed to compare between the therapeutic effects of stem cell-derived CM and exosomes on induced animal model of polycystic ovary. Polycystic ovary (PCO) was induced in female rats (3-4 weeks old, weighing 70-80 g) by letrozole with a dose of 1 mg/kg/day dissolved in carboxymethylcellulose 1% orally once daily for 5 weeks. Animals were divided into four groups: control group, PCO group, EXO-treated group, and CM-treated group. Serum levels of testosterone hormone, leutinizing hormone, follicle stimulatimg hormone, and insulin hormone were estimated. Immunohistochemistry using anti-P53, anti-AMP-dependent protein kinase antibodies were done. Six rats/group were used for matting with adult male rats for testing fertility. The results showed that CM had significant superior therapeutic effects on exosomes in restoring the normal histological architecture of the ovary and fertility. In summary, cell free treatment is a safe approach for tissue regeneration. Stem cell-derived CM was more effective than exosomes in restoring normal histological structure of the ovaries and fertility in animal models of polycystic ovary.

Design and Implement Strategy of Wireless Bite Force Device

Abnormal bite force is an important risk factor for oral and maxillofacial disorders, which is a critical dilemma that dentists face every day without effective solutions. Therefore, it is of great clinical significance to develop a wireless bite force measurement device and explore quantitative measurement methods to help find effective strategies for improving occlusal diseases. This study designed the open window carrier of a bite force detection device through 3D printing technology, and then the stress sensors were integrated and embedded into a hollow structure. The sensor system mainly consisted of a pressure signal acquisition module, a main control module, and a server terminal. A machine learning algorithm will be leveraged for bite force data processing and parameter configuration in the future. This study implemented a sensor prototype system from scratch to fully evaluate each component of the intelligent device. The experimental results showed reasonable parameter metrics for the device carrier and demonstrated the feasibility of the proposed scheme for bite force measurement. An intelligent and wireless bite force device with a stress sensor system is a promising approach to occlusal disease diagnosis and treatment.

Deep learning for osteoarthritis classification in temporomandibular joint

OBJECTIVES

This study aimed to develop a diagnostic support tool using pretrained models for classifying panoramic images of the temporomandibular joint (TMJ) into normal and osteoarthritis (OA) cases.

SUBJECTS AND METHODS

A total of 858 panoramic images of the TMJ (395 normal and 463 TMJ-OA) were obtained from 518 individuals from January 2015 to December 2018. The data were randomly divided into training, validation, and testing sets (6:2:2). We used pretrained Resnet152 and EfficientNet-B7 as transfer learning models. The accuracy, specificity, sensitivity, area under the curve, and gradient-weighted class activation mapping (grad-CAM) of both trained models were evaluated. The performances of the trained models were compared to that of dentists (both TMD specialists and general dentists).

RESULTS

The classification accuracies of ResNet-152 and EfficientNet-B7 were 0.87 and 0.88, respectively. The trained models exhibited the highest accuracy in OA classification. In the grad-CAM analysis, the trained models focused on specific areas in osteoarthritis images where erosion or osteophyte were observed.

CONCLUSIONS

The artificial intelligence model improved the diagnostic power of TMJ-OA when trained with two-dimensional panoramic condyle images and can be effectively applied by dentists as a screening diagnostic tool for TMJ-OA.

Regulation of Adenine Nucleotide Metabolism by Adenylate Kinase Isozymes: Physiological Roles and Diseases

Adenylate kinase (AK) regulates adenine nucleotide metabolism and catalyzes the ATP + AMP ⇌ 2ADP reaction in a wide range of organisms and bacteria. AKs regulate adenine nucleotide ratios in different intracellular compartments and maintain the homeostasis of the intracellular nucleotide metabolism necessary for growth, differentiation, and motility. To date, nine isozymes have been identified and their functions have been analyzed. Moreover, the dynamics of the intracellular energy metabolism, diseases caused by AK mutations, the relationship with carcinogenesis, and circadian rhythms have recently been reported. This article summarizes the current knowledge regarding the physiological roles of AK isozymes in different diseases. In particular, this review focused on the symptoms caused by mutated AK isozymes in humans and phenotypic changes arising from altered gene expression in animal models. The future analysis of intracellular, extracellular, and intercellular energy metabolism with a focus on AK will aid in a wide range of new therapeutic approaches for various diseases, including cancer, lifestyle-related diseases, and aging.

Conditioned Medium - Is it an Undervalued Lab Waste with the Potential for Osteoarthritis Management?

BACKGROUND

The approaches currently used in osteoarthritis (OA) are mainly short-term solutions with unsatisfactory outcomes. Cell-based therapies are still controversial (in terms of the sources of cells and the results) and require strict culture protocol, quality control, and may have side-effects. A distinct population of stromal cells has an interesting secretome composition that is underrated and commonly ends up as biological waste. Their unique properties could be used to improve the existing techniques due to protective and anti-ageing properties.

SCOPE OF REVIEW

In this review, we seek to outline the advantages of the use of conditioned media (CM) and exosomes, which render them superior to other cell-based methods, and to summarise current information on the composition of CM and their effect on chondrocytes.

MAJOR CONCLUSIONS

CM are obtainable from a variety of mesenchymal stromal cell (MSC) sources, such as adipose tissue, bone marrow and umbilical cord, which is significant to their composition. The components present in CMs include proteins, cytokines, growth factors, chemokines, lipids and ncRNA with a variety of functions. In most in vitro and in vivo studies CM from MSCs had a beneficial effect in enhance processes associated with chondrocyte OA pathomechanism.

GENERAL SIGNIFICANCE

This review summarises the information available in the literature on the function of components most commonly detected in MSC-conditioned media, as well as the effect of CM on OA chondrocytes in in vitro culture. It also highlights the need to standardise protocols for obtaining CM, and to conduct clinical trials to transfer the effects obtained in vitro to human subjects.

Global Trends and Future Research Directions for Temporomandibular Disorders and Stem Cells

Temporomandibular disorder (TMD) is an umbrella term used to describe various conditions that affect temporomandibular joints, masticatory muscles, and associated structures. Although the most conservative and least invasive treatment is preferable, more invasive therapies should be employed to refractory patients. Tissue engineering has been presented as a promising therapy. Our study aimed to investigate trends and point out future research directions on TMD and stem cells. A comprehensive search was carried out in the Web of Science Core Collection (WoS-CC) in October 2022. The bibliometric parameters were analyzed through descriptive statistics and graphical mapping. Thus, 125 papers, published between 1992 and 2022 in 65 journals, were selected. The period with the highest number of publications and citations was between 2012 and 2022. China has produced the most publications on the subject. The most frequently used keywords were "cartilage", "temporomandibular joint", "mesenchymal stem cells", and "osteoarthritis". Moreover, the primary type of study was in vivo. It was noticed that using stem cells to improve temporomandibular joint repair and regeneration is a significant subject of investigation. Nonetheless, a greater understanding of the biological interaction and the benefits of using these cells in patients with TMD is required.

Therapeutic effect of alendronate in an experimental temporomandibular joint osteoarthritis

BACKGROUND

Temporomandibular joint osteoarthritis is a common degenerative joint disease. This disease negatively affects the daily life, speech and chewing functions of patients.

OBJECTIVE

This study aimed to evaluate the effects of intra-articular injection of alendronate to osteoarthritis, which has a protective effect on bone and cartilage tissue and helps reduce inflammation in temporomandibular joint osteoarthritis.

METHODS

A total of 24 Wistar albino rats were used in the study. Rats were divided into four groups: study, saline, control and sham. In both saline and control groups, monosodium iodoacetate was injected intra-articularly to induce osteoarthritis. Alendronate was administered intra-articularly to the study group weekly for 4 weeks. In the saline group, saline was administered by intra-articular injection. At the end of the 12th week, all groups were sacrificed. Mandibular condyle tissues were examined histopathologically.

RESULTS

According to the results, osteoarthritic changes in the control group were higher than those in the study group (p < .05). No significant reduction in osteoarthritic changes was observed in the saline group (p > .05). Significant osteoarthritis findings were observed in all groups compared with the sham group (p < .05).

CONCLUSION

Intra-articular injection of alendronate was found to have positive results on TMJ osteoarthritis. In addition, it was seen that alendronate has effects on reducing cartilage tissue degeneration and loss of matrix proteins.

Osteoarthritis: Pathogenesis, Animal Models, and New Regenerative Therapies

Osteoarthritis (OA) is a chronic, progressive, multifactorial disease resulting in a progressive loss of articular cartilage structure and function that is most common in middle-aged and older patients. OA is involved in the loss of extracellular matrix and cartilage as well as cell number decreases within the matrix, especially in the further stages of the disease. The immune system plays a pivotal role in the pathomechanism of this condition. Both humoral and cellular mediators contribute to cartilage destruction, abnormal bone remodeling, synovitis, and joint effusion. The increasing prevalence of this disease has led to a growing interest in using animal models as the primary way to broaden the knowledge of the pathogenesis of OA and possible therapies at each stage of disease development. This review aims to describe the signs, pathogenesis, and classification of OA as well as discuss the advantages and disadvantages of some animal models. The currently used treatment methods include mesenchymal stem cells, exosomes, gene therapies, and blood-derived products. In addition, exogenous growth factors, platelet-rich plasma (PRP), platelet lysate, and autologous conditioned serum (ACS) are discussed with the application of tissue engineering techniques and biomaterials.

Effect of intervertebral disc degeneration on the stomatognathic system function in adults

OBJECTIVE

To analyze the electromyographic activity (EMG) and thermographic patterns of the masseter and temporalis muscles and pressure of the orofacial tissues in individuals with intervertebral disc degeneration (IDD).

METHODS

This study had two distinct groups: with IDD (n = 16) and controls (n = 16). EMG at rest, protrusion, right and left laterality, and maximum voluntary contraction were evaluated. Tongue, orbicularis oris, and buccinator muscles pressures were measured by Iowa Oral Performance Instrument. The thermographic patterns were analyzed using infrared thermography.

RESULTS

Comparisons between groups showed significant differences regarding at rest [right (p = 0.05) and left (p = 0.05) masseter and right temporal (p = 0.05)], orofacial tissue pressure [tongue (p = 0.001), orbicularis oris (p = 0.01), and buccinator (p = 0.0001)], but no significant differences for the thermographic patterns.

CONCLUSION

IDD modifies the functionality of the craniomandibular complex, influencing the performance of the stomatognathic system.

Efficacy analysis of splint combined with platelet-rich plasma in the treatment of temporomandibular joint osteoarthritis

Objective: To evaluate the efficacy of splints combined with PRP for the treatment of temporomandibular joint osteoarthritis. Methods: Thirty-one patients with temporomandibular joint osteoarthritis who were treated with splints combined with platelet-rich plasma (PRP) from January 2021 to June 2021 at the Department of Oral and Maxillofacial Surgery, School of Stomatology, China Medical University (Shenyang, China) were retrospectively reviewed. The VAS scores of all the patients were recorded before and 6 months after treatment, and the maximum comfortable mouth opening was recorded. All data were analyzed by the paired t-test using SPSS software, and a p-value < 0.05 indicated statistically significant differences. Results: Splint + PRP treatment was successful in 31 patients. The mean pretreatment VAS score was 6.1, and the mean VAS score 6 months posttreatment was 4.1. The posttreatment VAS score was significantly lower than the preoperative VAS score (p < 0.05). The mean pretreatment maximum comfortable mouth opening (MCMO) was 27.6 mm, and the mean MCMO 6 months posttreatment was 34.8 mm. The MCMO was significantly increased (p < 0.05). Conclusion: Splint + PRP is an effective treatment for temporomandibular joint osteoarthritis.

The potential therapeutic role of extracellular vesicles in osteoarthritis

Osteoarthritis (OA) is a worldwide and disabling disease, which cause severe pain and heavy socioeconomic burden. However, pharmacologic or surgical therapies cannot mitigate OA progression. Mesenchymal stem cells (MSCs) therapy has emerged as potential approach for OA treatment, while the immunogenicity and ethical audit of cell therapy are unavoidable. Compared with stem cell strategy, EVs induce less immunological rejection, and they are more stable for storage and in vivo application. MSC-EVs-based therapy possesses great potential in regulating inflammation and promoting cartilage matrix reconstruction in OA treatment. To enhance the therapeutic effect, delivery efficiency, tissue specificity and safety, EVs can be engineered via different modification strategies. Here, the application of MSC-EVs in OA treatment and the potential underlying mechanism were summarized. Moreover, EV modification strategies including indirect MSC modification and direct EV modification were reviewed.

EFFECTIVENESS OF INTRA-ARTICULAR INJECTIONS OF SODIUM HYALURONATE, CORTICOSTEROIDS, PLATELET-RICH PLASMA ON TEMPOROMANDIBULAR JOINT OSTEOARTHRITIS: A SYSTEMATIC REVIEW AND NETWORK META-ANALYSIS OF RANDOMIZED CONTROLLED TRIALS

OBJECTIVE

To compare the efficacy of Intra-articular injections of corticosteroids (CCS), hyaluronic acid (HA), and platelet-rich plasma (PRP) on temporomandibular joint osteoarthritis.

METHODS

Studies were identified from PubMed, Embase and Cochrane Central Register of Controlled Trials, ClinicalTrials.gov with date up to January 15, 2022. Randomized controlled trials included were the studies of patients with temporomandibular joint osteoarthritis who had intra-articular treatment with CCS, HA, PRP, placebo and follow-up assessing temporomandibular joint function in target outcome variables. The primary outcome was temporomandibular joint pain. The secondary outcomes were maximal mouth opening (mm), and lateral movement to the affected side (mm). This study is registered with PROSPERO, number CRD42021270914.

RESULTS

Nine randomized controlled trials involving 316 patients were included. For primary pain outcome, no significance was detected when CCS, HA and PRP were compared with placebo by both short- (3-6 months) and long-term (>12 months) follow-up. Relatively, the top ranking of which was PRP in the long-term (Mean Difference, -0.23 [95% CI, -2.49 to 2.04]). In addition, these injectables did not significantly outperform placebo by evaluating secondary functional outcomes (maximal mouth opening and lateral movement) with the same follow-up. Subgroup analyses showed that the effect of CCS on subgroups with more than 70% women was statistically less effective compared with placebo (Mean Difference, 1.73 [95% CI, 0.37-3.09]).

CONCLUSION

Evidence suggested that intra-articular pharmacological injections of CCS, HA, and PRP had no effect on improving temporomandibular joint pain and functional outcomes compared with placebo injection.

Clinical factors affecting depression in patients with painful temporomandibular disorders during the COVID-19 pandemic

Temporomandibular disorders (TMD) are a multifactorial condition associated with both physical and psychological factors. Stress has been known to trigger or worsens TMD. We aimed to investigate whether the novel coronavirus disease-2019 (COVID-19) pandemic aggravates depression in patients with painful TMD, and the factors that affect their level of depression. We included 112 patients with painful TMD (74 females, 38 males; mean age: 35.90 ± 17.60 years; myalgia [n = 38], arthralgia [n = 43], mixed joint-muscle TMD pain [n = 31]). TMD was diagnosed based on the Diagnostic Criteria for TMD Axis I. Physical pain intensity was recorded using the visual analog scale (VAS); psycho-emotional status (depression: Beck Depression Inventory [BDI], anxiety: Beck Anxiety Inventory [BAI], and generalized stress related to COVID19: Global Assessment of Recent Stress [GARS]) was investigated twice (before [BC] and after COVID-19 [AC]). Additionally, factors affecting BDI-AC were investigated. BDI (p < 0.001), BAI (p < 0.001), GARS (p < 0.001), and VAS (p < 0.01) scores were significantly increased at AC than BC. The depression, anxiety, and stress levels were significantly positively correlated, and the AC and BC values of each factor showed a high correlation. In the mixed TMD group, BDI-AC was positively correlated with VAS-AC (p < 0.001). In the multiple regression analysis, clenching habit was the strongest predictor of an increase in the BDI scores from moderate to severe, followed by psychological distress, muscle stiffness, female sex, BAI-AC, and TMJ sounds. COVID-19 has negatively affected the psycho-emotional state of patients with painful TMD, and several clinical factors, including female sex and clenching habits, have influenced depression.

Emerging role of mesenchymal stromal cells (MSCs)-derived exosome in neurodegeneration-associated conditions: a groundbreaking cell-free approach

Accumulating proofs signify that pleiotropic effects of mesenchymal stromal cells (MSCs) are not allied to their differentiation competencies but rather are mediated mainly by the releases of soluble paracrine mediators, making them a reasonable therapeutic option to enable damaged tissue repair. Due to their unique immunomodulatory and regenerative attributes, the MSC-derived exosomes hold great potential to treat neurodegeneration-associated neurological diseases. Exosome treatment circumvents drawbacks regarding the direct administration of MSCs, such as tumor formation or reduced infiltration and migration to brain tissue. Noteworthy, MSCs-derived exosomes can cross the blood-brain barrier (BBB) and then efficiently deliver their cargo (e.g., protein, miRNAs, lipid, and mRNA) to damaged brain tissue. These biomolecules influence various biological processes (e.g., survival, proliferation, migration, etc.) in neurons, oligodendrocytes, and astrocytes. Various studies have shown that the systemic or local administration of MSCs-derived exosome could lead to the favored outcome in animals with neurodegeneration-associated disease mainly by supporting BBB integrity, eliciting pro-angiogenic effects, attenuating neuroinflammation, and promoting neurogenesis in vivo. In the present review, we will deliver an overview of the therapeutic benefits of MSCs-derived exosome therapy to ameliorate the pathological symptoms of acute and chronic neurodegenerative disease. Also, the underlying mechanism behind these favored effects has been elucidated.

Exosomes in osteoarthritis: Updated insights on pathogenesis, diagnosis, and treatment

Osteoarthritis (OA) has remained a prevalent public health problem worldwide over the past decades. OA is a global challenge because its specific pathogenesis is unclear, and no effective disease-modifying drugs are currently available. Exosomes are small and single-membrane vesicles secreted via the formation of endocytic vesicles and multivesicular bodies (MVBs), which are eventually released when MVBs fuse with the plasma membrane. Exosomes contain various integral surface proteins derived from cells, intercellular proteins, DNAs, RNAs, amino acids, and metabolites. By transferring complex constituents and promoting macrophages to generate chemokines and proinflammatory cytokines, exosomes function in pathophysiological processes in OA, including local inflammation, cartilage calcification and degradation of osteoarthritic joints. Exosomes are also detected in synovial fluid and plasma, and their levels continuously change with OA progression. Thus, exosomes, specifically exosomal miRNAs and lncRNAs, potentially represent multicomponent diagnostic biomarkers for OA. Exosomes derived from various types of mesenchymal stem cells and other cell or tissue types affect angiogenesis, inflammation, and bone remodeling. These exosomes exhibit promising capabilities to restore OA cartilage, attenuate inflammation, and balance cartilage matrix formation and degradation, thus demonstrating therapeutic potential in OA. In combination with biocompatible and highly adhesive materials, such as hydrogels and cryogels, exosomes may facilitate cartilage tissue engineering therapies for OA. Based on numerous recent studies, we summarized the latent mechanisms and clinical value of exosomes in OA in this review.

Advantages of deep learning with convolutional neural network in detecting disc displacement of the temporomandibular joint in magnetic resonance imaging

This study investigated the usefulness of deep learning-based automatic detection of anterior disc displacement (ADD) from magnetic resonance imaging (MRI) of patients with temporomandibular joint disorder (TMD). Sagittal MRI images of 2520 TMJs were collected from 861 men and 399 women (average age 37.33 ± 18.83 years). A deep learning algorithm with a convolutional neural network was developed. Data augmentation and the Adam optimizer were applied to reduce the risk of overfitting the deep-learning model. The prediction performances were compared between the models and human experts based on areas under the curve (AUCs). The fine-tuning model showed excellent prediction performance (AUC = 0.8775) and acceptable accuracy (approximately 77%). Comparing the AUC values of the from-scratch (0.8269) and freeze models (0.5858) showed lower performances of the other models compared to the fine-tuning model. In Grad-CAM visualizations, the fine-tuning scheme focused more on the TMJ disc when judging ADD, and the sparsity was higher than that of the from-scratch scheme (84.69% vs. 55.61%, p < 0.05). The three fine-tuned ensemble models using different data augmentation techniques showed a prediction accuracy of 83%. Moreover, the AUC values of ADD were higher when patients with TMD were divided by age (0.8549–0.9275) and sex (male: 0.8483, female: 0.9276). While the accuracy of the ensemble model was higher than that of human experts, the difference was not significant (p = 0.1987–0.0671). Learning from pre-trained weights allowed the fine-tuning model to outperform the from-scratch model. Another benefit of the fine-tuning model for diagnosing ADD of TMJ in Grad-CAM analysis was the deactivation of unwanted gradient values to provide clearer visualizations compared to the from-scratch model. The Grad-CAM visualizations also agreed with the model learned through important features in the joint disc area. The accuracy was further improved by an ensemble of three fine-tuning models using diversified data. The main benefits of this model were the higher specificity compared to human experts, which may be useful for preventing true negative cases, and the maintenance of its prediction accuracy across sexes and ages, suggesting a generalized prediction.

Exosome Processing and Characterization Approaches for Research and Technology Development

Exosomes are extracellular vesicles that share components of their parent cells and are attractive in biotechnology and biomedical research as potential disease biomarkers as well as therapeutic agents. Crucial to realizing this potential is the ability to manufacture high-quality exosomes; however, unlike biologics such as proteins, exosomes lack standardized Good Manufacturing Practices for their processing and characterization. Furthermore, there is a lack of well-characterized reference exosome materials to aid in selection of methods for exosome isolation, purification, and analysis. This review informs exosome research and technology development by comparing exosome processing and characterization methods and recommending exosome workflows. This review also provides a detailed introduction to exosomes, including their physical and chemical properties, roles in normal biological processes and in disease progression, and summarizes some of the on-going clinical trials.

Bone Cell Exosomes and Emerging Strategies in Bone Engineering

Bone tissue remodeling is a highly regulated process balancing bone formation and resorption through complex cellular crosstalk between resident bone and microenvironment cells. This cellular communication is mediated by direct cell and cell–matrix contact, autocrine, endocrine, and paracrine receptor mediated mechanisms such as local soluble signaling molecules and extracellular vesicles including nanometer sized exosomes. An impairment in this balanced process leads to development of pathological conditions. Bone tissue engineering is an emerging interdisciplinary field with potential to address bone defects and disorders by synthesizing three-dimensional bone substitutes embedded with cells for clinical implantation. However, current cell-based therapeutic approaches have faced hurdles due to safety and ethical concerns, challenging their clinical translation. Recent studies on exosome-regulated bone homeostasis and regeneration have gained interest as prospective cell free therapy in conjugation with tissue engineered bone grafts. However, exosome research is still in its nascent stages of bone tissue engineering. In this review, we specifically describe the role of exosomes secreted by cells within bone microenvironment such as osteoblasts, osteocytes, osteoclasts, mesenchymal stem cell cells, immune cells, endothelial cells, and even tumor cells during bone homeostasis and crosstalk. We also review exosome-based osteoinductive functionalization strategies for various bone-based biomaterials such as ceramics, polymers, and metals in bone tissue engineering. We further highlight biomaterials as carrier agents for exosome delivery to bone defect sites and, finally, the influence of various biomaterials in modulation of cell exosome secretome.

Noncoding RNA in Extracellular Vesicles Regulate Differentiation of Mesenchymal Stem Cells

To achieve the desired outcome in tissue engineering regeneration, mesenchymal stem cells need to undergo a series of biological processes, including differentiating into the ideal target cells. The extracellular vesicle (EV) in the microenvironment contributes toward determining the fate of the cells with epigenetic regulation, particularly from noncoding RNA (ncRNA), and exerts transportation and protective effects on ncRNAs. We focused on the components and functions of ncRNA (particularly microRNA) in the EVs. The EVs modified by the ncRNA favor tissue regeneration and pose a potential challenge.

Experimental functional shift-induced osteoarthritis-like changes at the TMJ and altered integrin expression in a rat model

Mandibular deviation affects the biomechanical environment of the temporomandibular joint (TMJ) and causes thinning of cartilage on the deviated side. We aimed to evaluate, using a rat model, the effect of mandibular functional deviation on the TMJ in relation to the functional roles of integrin β family members. The effects of experimental functional deviation on the TMJ of 6-week-old Sprague-Dawley female rats, randomly assigned to control (n = 42) and experimental groups (n = 42), were evaluated at 3 days and 1, 2, 4, and 8 weeks by histological staining, immunofluorescence, real-time quantitative polymerase chain reaction, and micro-computed tomography. The results showed that the experimental functional shift changed the shape of condyles, thinned the cartilage, and increased the proportion of the hypertrophic layer on the deviated sides of condyles. In addition, the extracellular matrix of the condyle cartilage exhibited degradation at 1 week and subchondral trabecular bone was lost at 4 and 8 weeks. Osteoarthritis (OA)-like changes occurred in the left and right condyles of rats in the experimental group and were aggravated over time. Integrin β family expression, especially integrin β₂ , was altered from week 1, possibly related to the OA-like changes. These data may provide insight into the onset of TMJ OA.

The promising role of autologous and allogeneic mesenchymal stromal cells in managing knee osteoarthritis. What is beyond Mesenchymal stromal cells?

Mesenchymal stromal cells (MSCs) express a wide range of properties anticipated to be beneficial for treating genetic, mechanical, and age-related degeneration in diseases such as osteoarthritis (OA). Although contemporary conservative management of OA is successful in many patients with mild-moderate OA, it often fails to improve symptoms in many patients who are not a candidate for any surgical management. Further, existing conservative treatment strategies do not prevent the progression of the disease and therefore fail to provide a long-term pain-free life. On the other hand, tremendous progress has been taking place in the exciting field of regenerative medicine involving MSCs (autologous and allogeneic), with promising translation taking place from basic science to the bedside. In this review, we comprehensively discuss the potential role of MSCs in treating OA, both autologous and off-the-shelf, allogeneic stem cells. Further, newer therapies are in the offing to treat OA, such as exosomes and growth factors.

Comparison of Clinical and Radiological Characteristics of Temporomandibular Joint Osteoarthritis in Older and Young people

Background and Objectives:

The relatively high prevalence of temporomandibular joint (TMJ) osteoarthritis (OA) in older people increases the necessity to investigate the specific characteristics of TMJ-OA in this particular population. This study aimed to analyze the longitudinal changes in clinical and radiological characteristics of TMJ-OA in older people.

Methods:

We retrospectively analyzed the clinical features and cone-beam computed tomography (CBCT) images of 76 participants with TMJ-OA. Participants were classified into two groups according to age. The older people group included 33 participants over 50 years of age, and the control group included 43 participants in their 15-29 years. We analyzed the differences in clinical features and the distribution of destructive bony changes on CBCT images between groups.

Results:

The duration of pain was significantly shorter in the older people group (P = .046); however, the treatment duration was significantly longer in the older people group (P = .001). There was a significant difference in the distribution of destructive bony features between groups (P = .005). In the older people group, “three or more features” (36.3%) were the most common, whereas in the control group, “erosion” (44.2%) was the most common. After treatment, there was little improvement in the frequency of “erosion” in the older people group. There was a significant difference in the proportion of erosion after treatment between the groups (P = .033).

Conclusion:

In older people with TMJ-OA, active treatment to effectively induce condylar remodeling should be considered.

Comparison of Clinical and Radiological Characteristics of Temporomandibular Joint Osteoarthritis in Older and Young people

Background and Objectives:

The relatively high prevalence of temporomandibular joint (TMJ) osteoarthritis (OA) in older people increases the necessity to investigate the specific characteristics of TMJ-OA in this particular population. This study aimed to analyze the longitudinal changes in clinical and radiological characteristics of TMJ-OA in older people.

Methods:

We retrospectively analyzed the clinical features and cone-beam computed tomography (CBCT) images of 76 participants with TMJ-OA. Participants were classified into two groups according to age. The older people group included 33 participants over 50 years of age, and the control group included 43 participants in their 15-29 years. We analyzed the differences in clinical features and the distribution of destructive bony changes on CBCT images between groups.

Results:

The duration of pain was significantly shorter in the older people group (P = .046); however, the treatment duration was significantly longer in the older people group (P = .001). There was a significant difference in the distribution of destructive bony features between groups (P = .005). In the older people group, “three or more features” (36.3%) were the most common, whereas in the control group, “erosion” (44.2%) was the most common. After treatment, there was little improvement in the frequency of “erosion” in the older people group. There was a significant difference in the proportion of erosion after treatment between the groups (P = .033).

Conclusion:

In older people with TMJ-OA, active treatment to effectively induce condylar remodeling should be considered.

Cryo-Temperature Pretreatment Increases the Pro-Angiogenic Capacity of Three-Dimensional Mesenchymal Stem Cells via the PI3K-AKT Pathway

To increase the potential and effectiveness of three-dimensional (3D) mesenchymal stem cells (MSCs) for clinical applications, this study explored the effects of short cryo-temperature pretreatment on MSC function. Adipose-derived MSCs (A-MSCs) were cultured via the ordinary monolayer method and 3D hanging drop spheroid method. When the cells adhered to the wall or formed a spheroid, they were subjected to hypothermic stress at 4°C for 1 h and then divided into three recovery periods at 37°C, specifically 0, 12, and 24 h. The control group was not subjected to any treatment throughout the study. Monolayer and 3D spheroid A-MSCs were analyzed via RNA sequencing after hypothermic stress at 4°C for 1 h. Subsequently, each group of cells was collected and subjected to phenotype identification via flow cytometry, and mRNA expression was detected via reverse transcription-quantitative polymerase chain reaction analysis. Western blot analysis was performed to analyze the PI3K-AKT signaling pathway in A-MSCs. The effects of A-MSCs on angiogenesis in vivo were examined using a chick chorioallantoic membrane assay. Transwell assays were performed to determine whether the culture supernatant from each group could induce the chemotaxis of human umbilical vein endothelial cells (HUVECs). Three-dimensional spheroid culture did not change the phenotype of A-MSCs. The expression of fibroblast growth factors, hepatocyte growth factors, and other angiogenesis-related factors in A-MSCs was upregulated. A-MSCs subjected to hypothermic stress promoted angiogenesis under both monolayer and 3D spheroid cultures. Moreover, the chemotaxis of HUVECs to the 3D spheroid culture supernatant increased substantially. Short cryo-temperature pretreatment could stimulate 3D spheroid A-MSCs and activate the PI3K-AKT pathway. This approach has the advantages of promoting angiogenesis and maintaining cell viability.