Extracellular Vesicles: An Emerging Regenerative Treatment for Oral Disease

Functions and Clinical Applications of Extracellular Vesicles in TH2 Cell-Mediated Airway Inflammatory Diseases: A Review

Type 2 airway inflammation (T2AI), driven by type 2 innate lymphoid and CD4+ T helper 2 cells, leads to various diseases and conditions, such as chronic rhinosinusitis with nasal polyps, allergic rhinitis, and asthma. Emerging evidence suggests the involvement of extracellular vesicles (EVs) in these diseases. In this review, we describe the immunological T2AI pathogenic mechanisms, outline EV characteristics, and highlight their applications in the diagnosis and treatment of T2AI. An extensive literature search was conducted using appropriate strategies to identify relevant articles from various online databases. EVs in various biological samples showed disease-specific characteristics for chronic rhinosinusitis with nasal polyps, allergic rhinitis, and asthma, with some demonstrating therapeutic effects against these conditions. However, most studies have been limited to in vitro and animal models, highlighting the need for further clinical research on the diagnostic and therapeutic applications of EVs.

Clinical Efficacy of Extracellular Vesicle Therapy in Periodontitis: Reduced Inflammation and Enhanced Regeneration

Periodontitis, a prevalent inflammatory condition, affects the supporting structures of teeth, leading to significant oral health challenges. Traditional treatments have primarily focused on mechanical debridement, antimicrobial therapy, and surgery, which often fail to restore lost periodontal structures. Emerging as a novel approach in regenerative medicine, extracellular vesicle (EV) therapy, including exosomes, leverages nano-sized vesicles known for facilitating intercellular communication and modulating physiological and pathological processes. This study is a proof-of-concept type that evaluates the clinical efficacy of EV therapy as a non-surgical treatment for stage I-III periodontitis, focusing on its anti-inflammatory and regenerative potential. The research involved seven patients undergoing the therapy, and seven healthy individuals. Clinical parameters, including the plaque index, bleeding on probing, probing depth, and attachment level, were assessed alongside cytokine levels in the gingival crevicular fluid. The study found significant improvements in clinical parameters, and a marked reduction in pro-inflammatory cytokines post-treatment, matching the levels of healthy subjects, underscoring the therapy's ability to not only attenuate inflammation and enhance tissue regeneration, but also highlighting its potential in restoring periodontal health. This investigation illuminates the promising role of EV therapy in periodontal treatment, advocating for a shift towards therapies that halt disease progression and promote structural and functional restoration of periodontal tissues.

Mechanism of adipose tissue-derived stromal cell-extracellular vesicles in treating oral submucous fibrosis by blocking the TGF-β1/Smad3 pathway via the miR-760-3p/IGF1R axis

Oral submucous fibrosis (OSF) is a prevalent chronic condition, and understanding its pathogenesis is crucial for developing effective therapeutic strategies. This study explores the potential of adipose tissue-derived stromal cell-extracellular vesicles (ADSC-EVs) in mitigating OSF and investigates the underlying molecular mechanisms. OSF was induced in mice by arecoline feeding. Adipose tissue-derived stromal cells (ADSCs), fibrotic buccal mucosal fibroblasts (fBMFs) isolated from OSF mice, and ADSC-EVs were comprehensively characterized. The treatment effects of extracellular vesicles (EVs) and pcDNA3.1-IGF1R on fBMF proliferation, migration, and invasion were assessed using Cell Counting Kit-8 (CCK-8) assay, transwell assay, and flow cytometry assay. The expression levels of alpha-smooth muscle actin (α-SMA), collagen I, collagen III, and insulin-like growth factor 1 receptor (IGF1R) were evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot. The interaction between miR-760-3p and IGF1R was investigated. In fBMFs and OSF mice treated with a miR-760-3p inhibitor and/or EVs, the expression patterns of miR-760-3p, IGF1R, and proteins related to the TGF-β1/Smad3 pathway were determined. ADSC-EVs demonstrated the ability to upregulate miR-760-3p, impede cell proliferation, migration, and invasion, and reduce α-SMA, collagen I, and collagen III levels in fBMFs. The expression of miR-760-3p was diminished in ADSC-EVs treated with a miR-760-3p inhibitor. However, silencing miR-760-3p or overexpressing IGF1R partially counteracted the beneficial effects of ADSC-EVs on fBMF fibrosis. miR-760-3p directly targets IGF1R. Significantly, ADSC-EVs exert their suppressive effects on the TGF-β1/Smad3 pathway through the miR-760-3p/IGF1R axis. In summary, ADSC-EVs, by transferring miR-760-3p and inhibiting IGF1R expression, effectively block the TGF-β1/Smad3 pathway, thereby alleviating fibrosis in fBMFs and preventing the progression of OSF.

Engineered Extracellular Vesicles: A potential treatment for regeneration

Extracellular vesicles (EVs) play a critical role in various physiological and pathological processes. EVs have gained recognition in regenerative medicine due to their biocompatibility and low immunogenicity. However, the practical application of EVs faces challenges such as limited targeting ability, low yield, and inadequate therapeutic effects. To overcome these limitations, engineered EVs have emerged. This review aims to comprehensively analyze the engineering methods utilized for modifying donor cells and EVs, with a focus on comparing the therapeutic potential between engineered and natural EVs. Additionally, it aims to investigate the specific cell effects that play a crucial role in promoting repair and regeneration, while also exploring the underlying mechanisms involved in the field of regenerative medicine.

Bioprinting extracellular vesicles as a "cell-free" regenerative medicine approach

Regenerative medicine involves the restoration of tissue or organ function via the regeneration of these structures. As promising regenerative medicine approaches, either extracellular vesicles (EVs) or bioprinting are emerging stars to regenerate various tissues and organs (i.e., bone and cardiac tissues). Emerging as highly attractive cell-free, off-the-shelf nanotherapeutic agents for tissue regeneration, EVs are bilayered lipid membrane particles that are secreted by all living cells and play a critical role as cell-to-cell communicators through an exchange of EV cargos of protein, genetic materials, and other biological components. 3D bioprinting, combining 3D printing and biology, is a state-of-the-art additive manufacturing technology that uses computer-aided processes to enable simultaneous patterning of 3D cells and tissue constructs in bioinks. Although developing an effective system for targeted EVs delivery remains challenging, 3D bioprinting may offer a promising means to improve EVs delivery efficiency with controlled loading and release. The potential application of 3D bioprinted EVs to regenerate tissues has attracted attention over the past few years. As such, it is timely to explore the potential and associated challenges of utilizing 3D bioprinted EVs as a novel "cell-free" alternative regenerative medicine approach. In this review, we describe the biogenesis and composition of EVs, and the challenge of isolating and characterizing small EVs - sEVs (< 200 nm). Common 3D bioprinting techniques are outlined and the issue of bioink printability is explored. After applying the following search strategy in PubMed: "bioprinted exosomes" or "3D bioprinted extracellular vesicles", eight studies utilizing bioprinted EVs were found that have been included in this scoping review. Current studies utilizing bioprinted sEVs for various in vitro and in vivo tissue regeneration applications, including angiogenesis, osteogenesis, immunomodulation, chondrogenesis and myogenesis, are discussed. Finally, we explore the current challenges and provide an outlook on possible refinements for bioprinted sEVs applications.

Mechanisms and clinical application potential of mesenchymal stem cells-derived extracellular vesicles in periodontal regeneration

Periodontitis is a high prevalence oral disease which damages both the hard and soft tissue of the periodontium, resulting in tooth mobility and even loss. Existing clinical treatment methods cannot fully achieve periodontal tissue regeneration; thus, due to the unique characteristics of mesenchymal stem cells (MSCs), they have become the focus of attention and may be the most promising new therapy for periodontitis. Accumulating evidence supports the view that the role of MSCs in regenerative medicine is mainly achieved by the paracrine pathway rather than direct proliferation and differentiation at the injured site. Various cells release lipid-enclosed particles known as extracellular vesicles (EVs), which are rich in bioactive substances. In periodontitis, EVs play a pivotal role in regulating the biological functions of both periodontal tissue cells and immune cells, as well as the local microenvironment, thereby promoting periodontal injury repair and tissue regeneration. As a cell-free therapy, MSCs-derived extracellular vesicles (MSC-EVs) have some preponderance on stability, immune rejection, ethical supervision, and other problems; therefore, they may have a broad clinical application prospect. Herein, we gave a brief introduction to MSC-EVs and focused on their mechanisms and clinical application in periodontal regeneration.

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.

Roles of extracellular vesicles in periodontal homeostasis and their therapeutic potential

Periodontal tissue is a highly dynamic and frequently stimulated area where homeostasis is easily destroyed, leading to proinflammatory periodontal diseases. Bacteria-bacteria and cell-bacteria interactions play pivotal roles in periodontal homeostasis and disease progression. Several reviews have comprehensively summarized the roles of bacteria and stem cells in periodontal homeostasis. However, they did not describe the roles of extracellular vesicles (EVs) from bacteria and cells. As communication mediators evolutionarily conserved from bacteria to eukaryotic cells, EVs secreted by bacteria or cells can mediate interactions between bacteria and their hosts, thereby offering great promise for the maintenance of periodontal homeostasis. This review offers an overview of EV biogenesis, the effects of EVs on periodontal homeostasis, and recent advances in EV-based periodontal regenerative strategies. Specifically, we document the pathogenic roles of bacteria-derived EVs (BEVs) in periodontal dyshomeostasis, focusing on plaque biofilm formation, immune evasion, inflammatory pathway activation and tissue destruction. Moreover, we summarize recent advancements in cell-derived EVs (CEVs) in periodontal homeostasis, emphasizing the multifunctional biological effects of CEVs on periodontal tissue regeneration. Finally, we discuss future challenges and practical perspectives for the clinical translation of EV-based therapies for periodontitis.

Clinical applications of pluripotent stem cells and their derivatives: current status and future perspectives

Pluripotent stem cells (PSCs) can differentiate into specific cell types and thus hold great promise in regenerative medicine to treat certain diseases. Hence, several studies have been performed harnessing their salutary properties in regenerative medicine. Despite several challenges associated with the clinical applications of PSCs, worldwide efforts are harnessing their potential in the regeneration of damaged tissues. Several clinical trials have been performed using PSCs or their derivatives. However, the delay in publishing the data obtained in the trials has led to a lack of awareness about their outcomes, resulting in apprehension about cellular therapies. Here, the authors review the published papers containing data from recent clinical trials done with PSCs. PSC-derived extracellular vesicles hold great potential in regenerative therapy. Since published papers containing the data obtained in clinical trials on PSC-derived extracellular vesicles are not available yet, the authors have reviewed some of the pre-clinical work done with them.

Advances in mesenchymal stem cell conditioned medium-mediated periodontal tissue regeneration

Periodontitis is a chronic inflammatory disease that leads to the destruction of both soft and hard periodontal tissues. Complete periodontal regeneration in clinics using the currently available treatment approaches is still a challenge. Mesenchymal stem cells (MSCs) have shown promising potential to regenerate periodontal tissue in various preclinical and clinical studies. The poor survival rate of MSCs during in vivo transplantation and host immunogenic reaction towards MSCs are the main drawbacks of direct use of MSCs in periodontal tissue regeneration. Autologous MSCs have limited sources and possess patient morbidity during harvesting. Direct use of allogenic MSCs could induce host immune reaction. Therefore, the MSC-based indirect treatment approach could be beneficial for periodontal regeneration in clinics. MSC culture conditioned medium (CM) contains secretomes that had shown immunomodulatory and tissue regenerative potential in pre-clinical and clinical studies. MSC-CM contains a cocktail of growth factors, cytokines, chemokines, enzymes, and exosomes, extracellular vesicles, etc. MSC-CM-based indirect treatment has the potential to eliminate the drawbacks of direct use of MSCs for periodontal tissue regeneration. MSC-CM holds the tremendous potential of bench-to-bed translation in periodontal regeneration applications. This review focuses on the accumulating evidence indicating the therapeutic potential of the MSC-CM in periodontal regeneration-related pre-clinical and clinical studies. Recent advances on MSC-CM-based periodontal regeneration, existing challenges, and prospects are well summarized as guidance to improve the effectiveness of MSC-CM on periodontal regeneration in clinics.