Dental Pulp Stem Cell-Derived Exosomes Regulate Anti-Inflammatory and Osteogenesis in Periodontal Ligament Stem Cells and Promote the Repair of Experimental Periodontitis in Rats

Small extracellular vesicles: the origins, current status, future prospects, and applications

Small extracellular vesicles (sEVs) are membrane-bound vesicles with a size of less than 200 nm, released by cells. Due to their relatively small molecular weight and ability to participate in intercellular communication, sEVs can serve not only as carriers of biomarkers for disease diagnosis but also as effective drug delivery agents. Furthermore, these vesicles are involved in regulating the onset and progression of various diseases, reflecting the physiological and functional states of cells. This paper introduces the classification of extracellular vesicles, with a focus on the extraction and identification of sEVs and their significant role in repair, diagnosis, and intercellular communication. Additionally, the paper addresses the engineering modification of sEVs to provide a reference for enhanced understanding and application.

Human dental follicle cell-derived conditioned media enhance periodontal regeneration by regulating the osteogenic differentiation and inflammation of periodontal ligament stem cells and macrophage polarization

Dental follicle cells (DFCs) derived from the neural crest are promising seed cells for periodontal tissue engineering. This study aimed to investigate whether conditioned media (CM) from human DFCs could regenerate impaired periodontal tissue and the underlying mechanisms. hDFC-derived CM (hDFC-CM) were obtained via ultracentrifugation. In vitro, human periodontal ligament stem cells (hPDLSCs) were treated with hDFC-CM in normal and inflammatory microenvironments, and the cell proliferation, migration, and osteogenic potential were evaluated. We simulated the inflammatory environment with lipopolysaccharide and detected the expression of osteogenic and Wnt/β-catenin signaling pathway-related proteins. The effect of hDFC-CM on the inhibition of hPDLSC inflammation and macrophage polarization was examined. In vivo, the rat periodontitis model was treated with hDFC-CM. Tissue samples were collected after 4 weeks for micro-computed tomography and histological examination. The results of cell counting kit-8 and scratch experiments showed that hDFC-CM significantly enhanced the proliferation and migration capacities of hPDLSCs. hDFC-CM promoted the osteogenic differentiation of hPDLSCs by showing intense alkaline phosphatase and Alizarin Red staining and upregulated osteogenic protein and gene expression. Western blotting also verified that hDFC-CM promotes the osteogenic differentiation of hPDLSCs by regulating the Wnt/β-catenin pathway in an inflammatory environment. In addition, hDFC-CM inhibited hPDLSC inflammation and polarized macrophages from the M1 to M2 phenotype. In vivo, hDFC-CM effectively promoted periodontal tissue regeneration. hDFC-CM enhances periodontal regeneration by regulating the osteogenic differentiation and inflammation of periodontal ligament stem cells and macrophage polarization, which provided new biochemical cues for the treatment of periodontitis.

Human Umbilical Cord Mesenchymal Stem Cells-Derived Exosomes Attenuates Experimental Periodontitis in Mice Partly by Delivering miRNAs

Introduction

Periodontitis is the most common non-communicable disease in humans. The main challenge in the treatment of periodontitis is to effectively control periodontal inflammation and promote tissue repair. Human umbilical cord mesenchymal stem cells-derived exosomes (hucMSCs-exo) have been reported to modulate inflammatory responses and promote tissue repairment mainly through miRNAs in several diseases. However, the effect of hucMSCs-exo on periodontitis remains unknown. In this study, we hypothesized that hucMSCs-exo could inhibit bone destruction in periodontitis mice.

Methods

In this study, we constructed and characterized the exo@H drug delivery platform. Lipopolysaccharide was used to construct an inflammatory microenvironment in vitro to detect MC3T3-E1 cells proliferation and bone regeneration capacity. Ligation induced to construct an experimental periodontitis mouse model. The distance of the cement-enamel junction (CEJ) to the alveolar bone crest (ABC) was measured for bone resorption evaluation. Hematoxylin-eosin (H&E) staining and Tartrate resistant acid phosphatase (TRAP) staining were used to observe periodontal tissue changes. MicroRNA (miRNA) sequencing was used to detect differential genes and for bioinformatics analysis. Real-time quantitative polymerase chain reaction (qRT-PCR). WB assay and dual luciferase assay were used to further validate the screened differentially expressed miRNAs and the targeted binding relationship with the corresponding target genes.

Results

We found that lyophilized hucMSCs-exo promoted the proliferation and osteogenic differentiation of MC3T3-E1 cells, and showed more significant proliferative and osteogenic differentiation abilities in combination with the hydrogel (P < 0.05). Using periodontitis mice, bone resorption evaluation revealed a significant reduction in alveolar bone resorption in the exo@H group compared to the hydrogel group (P < 0.01), and exo@H was able to reduce the inflammatory response of periodontal tissues and the number of osteoclasts on the surface of the alveolar bone compared to the hydrogel group. Moreover, 59 miRNAs were upregulated, such as let-7f-5p and miR-203-3p, which positively targeted IL-13 and Nit2, respectively.

Discussion

These results suggest that exo@H provides protection against periodontitis partly by delivering miRNAs to periodontal tissue. Our results confirm the feasibility of the exo@H delivery platform we constructed and the effectiveness of its use for periodontitis treatment, and this study provides a promising approach for the treatment of periodontitis via miRNA.

Circ-SPATA13 regulates the osteogenic differentiation of human periodontal ligament stem cells through the miR-485-5p_R + 1/BMP7 axis

BACKGROUND

Human periodontal ligament stem cells (PDLSCs) are widely available and have strong osteogenic differentiation ability, which makes them promising tools for bone regeneration. Circular RNAs (circRNAs) play a variety of functions in the process of cell differentiation and are potential therapeutic targets. Here, we identified a new circRNA, circ-SPATA13, and found that it was highly positively correlated with the osteogenic differentiation of PDLSCs. Therefore, in this study, we revealed the significance and mechanism of circ-SPATA13 in the osteogenic differentiation of PDLSCs.

METHODS

PDLSCs were isolated from third molars with incomplete apical development and induced to undergo chondrogenic, adipogenic, or osteogenic differentiation. Surface markers were detected via flow cytometry. Proliferation was assessed with EdU and CCK-8 assays. The circ-SPATA13 and miR-485-5p_R + 1-mediated control of mineral deposition was evaluated through alizarin red and alkaline phosphatase staining. Osteogenesis-related factor expression was detected through western blotting, immunofluorescence, and qRT-PCR. Fluorescence in situ hybridization was used to examine circ-SPATA13 localization within PDLSCs. The relationships among circ-SPATA13, miR-485-5p_R + 1, and BMP7 during PDLSCs osteogenesis were assessed through western blotting, qRT-PCR, dual-luciferase assay, rescue experiment, and bioinformatics approaches.

RESULTS

Primary PDLSCs expressing mesenchymal stem cell surface markers were isolated. Circ-SPATA13 was identified and found to have no impact on PDLSC proliferation, whereas it was a positive regulator of their osteogenic differentiation, a process which was antagonized by miR-485-5p_R + 1. Dual-luciferase reporter assays revealed that circ-SPATA13 was able to function as a molecular sponge to sequester miR-485-5p_R + 1 within PDLSCs, while this miRNA was able to bind to the 3'-UTR of the target mRNA BMP7. In rescue experiments, circ-SPATA13 was confirmed to regulate the osteogenic differentiation of PDLSCs via this miR-485-5p_R + 1/BMP7 axis. Moreover, in vivo experiments in rats demonstrated that the overexpression of circ-SPATA13 in PDLSCs was associated with the promotion of bone formation in a skull defect model system.

CONCLUSION

These data supported the osteogenic functions of circ-SPATA13 in PDLSCs. Mechanistically, this circRNA was found to function as a molecular sponge for miR-485-5p_R + 1, in turn targeting BMP7 to promote the osteogenic differentiation of PDLSCs. This circ-SPATA13/miR-485-5p_R + 1/BMP7 axis may be a novel target for treatments promoting PDLSCs osteogenic differentiation.

The micro CT evaluation of crown and root pulp volume versus dentin thickness in teeth in postmortem interval (PMI)

Determining the postmortem interval (PMI) is one of the main study subjects of forensic sciences. The main purpose of this prospective in vitro study that was the Micro-CT evaluation of teeth crown and root pulp volume versus dentin thickness in terms of PMI determination. The study involved 60 female Wistar rats, with weights ranging from 270 to 320 g. These rats were grouped into six different post-mortem period categories. Following the animals' sacrifice, they were subjected to a natural putrefaction period, with a control group, in the grounds of a sheltered garden. Hemi-mandible samples were then extracted and placed in glass tubes for Micro-CT evaluations, following the progression of putrefaction processes. The pulp volume and dentin thickness were assessed using Micro-CT, and the gathered data underwent statistical analysis. Micro-CT was employed to analyze sixty right mandibular second molar teeth in the hemi-mandible. The crown pulp volume exhibited a reduction in group 6, with a value of 0.239 mm3 after a three-month period of natural putrefaction (p < 0.001). There is statistically differences among groups in case of pairwise comparison (p < 0.05). However, the root pulp volume and dentin thickness variables did not display any statistically significant changes. Despite certain limitations associated with this study, the Micro-CT findings concerning teeth pulp volume can serve as an objective parameter, especially for late postmortem investigations and the estimation of time of death.

Age-Related Oral and Para-Oral Tissue Disorders: The Evolving Therapeutic and Diagnostic Potential of Exosomes

This review highlights the key molecular and cellular mechanisms contributing to aging, such as DNA damage, mitochondrial dysfunction, telomere shortening, protein dysfunction, and defective autophagy. These biological mechanisms are involved in various oral health conditions prevalent in the elderly, including periodontal disease, oral cancer, xerostomia, dental caries, and temporomandibular joint disorders. Exosomes generated by mesenchymal stem cells possess substantial therapeutic potential. These exosomes are nanosized extracellular vesicles derived from cells and are involved in essential intercellular communication and tissue homeostasis. The exosome-based therapies proved superior to traditional cell-based approaches, due to lower immunogenicity, ease of storage, and avoidance of complications associated with cell transplantation. Furthermore, the diagnostic potential of exosomes as non-invasive biomarkers for aging processes and age-related oral diseases offers insights into disease diagnosis, staging, and monitoring. Among the challenges and future perspectives of translating exosome research from preclinical studies to clinical applications is the need for standardized procedures to fully harness the therapeutic and diagnostic capabilities of exosomes.

Human dental follicle stem cell-derived exosomes reduce root resorption by inhibiting periodontal ligament cell pyroptosis

BACKGROUND

To explore the therapeutic effects and mechanisms of the exosomes derived from dental follicle stem cells (DFSC-Exos) in reducing osteoclastogenesis and root resorption (RR) by inhibiting periodontal ligament cell (PDLC) pyroptosis.

METHODS

DFSC-Exos, with force stimulation (Force-Exos) or without (Ctrl-Exos), were co-cultured with human PDLCs in vitro and injected into the periodontal ligament (PDL) of rats following the establishment of RR models in vivo. Subsequently, resorption volume, PDLC pyroptotic ratio, and NLRP3-mediated pyroptosis pathway activation were performed to investigate the therapeutic effects of DFSC-Exos on PDLC pyroptosis during RR. Furthermore, the number of M1/M2 macrophages, osteoclast formation, and transwell polarization elucidated the role of Force-Exo treatment in macrophage polarization and osteoclastogenesis by inhibiting pyroptosis. Exosomal miRNA sequencing and bioinformatic analysis were used to identify differentially abundant exosome-derived miRNAs, as well as the dominant biological processes and pathways modulated by miRNA. The administration of miRNA inhibitors further verified the regulation of exosomal miRNA on RR via modulating pyroptosis. Moreover, the potential mechanisms involving candidate miRNAs and relevant pathways were explored.

RESULTS

Exosomes released by force-stimulated DFSCs (Force-Exos) inhibited NOD-like receptor 3 (NLRP3)-mediated PDLC pyroptosis, which impacted M1 macrophage activation and osteoclast formation. Based on exosomal miRNA sequencing, miR-140-3p in Force-Exos were transferred to PDLCs, and the administration of miR-140-3p inhibitors significantly reversed the reduction in PDLC pyroptosis, M1 macrophage polarization, osteoclast number, and resorption volume caused by Force-Exos. More importantly, mechanistic studies demonstrated that miR-140-3p mediated the function of Force-Exos by targeting DNA methyltransferase 1 (DNMT1) to alter the DNA methylation of suppressor of cytokine signaling (SOCS1) and the downstream nuclear factor κB (NF-κB) signaling pathway in PDLCs. Blocking the DNMT1/SOCS1/NFκB axis with DFSC-derived exosomal miR-140-3p downregulated NLRP3-mediated PDLC pyroptosis to impact M1 polarization and osteoclast formation, thereby alleviating RR.

CONCLUSION

DFSC-Exos downregulated NLRP3-mediated PDLC pyroptosis via miR-140-3p to block DNMT1/SOCS1/NFκB axis, which impacted M1 polarization and osteoclast formation, thereby alleviating RR.

Potential of mir-299-5p to modulate LPS-induced inflammation and osteogenic differentiation of periodontal stem cells by targeting PUM2

BACKGROUND

Periodontitis is a prevalent oral disease that significantly impacts human quality of life. This study aimed at the influence of microRNA-299-5p (miR-299-5p) on regulating lipopolysaccharide (LPS)-induced osteogenic differentiation of periodontal ligament stem cells (PDLSCs).

METHODS

The 105 periodontitis patients and 102 healthy periodontal volunteers (HC) were recruited with their clinical baseline data. miR-299-5p expression in saliva was measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR). To identify the target relationship between miR-299-5p and pumilio RNA-binding family member 2 (PUM2), the dual luciferase reporter gene was explored. PDLSCs were treated with LPS and subjected to osteogenic differentiation induction. The secretion of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β) was determined by enzyme-linked immunosorbent assay. mRNA expression of runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), and osteocalcin (OCN) was detected by qRT-PCR.

RESULTS

miR-299-5p expression was markedly reduced in periodontitis patients' saliva and negatively correlated with patients' attachment loss, bleeding index, plaque index, probing pocket depth, and TNF-α, IL-6, and IL-1β levels. miR-299-5p could be well distinguished between periodontitis and HC. LPS induction dramatically stimulated the secretion of inflammatory factors and inhibited the differentiation of PDLSCs, which was counteracted by miR-299-5p overexpression. miR-299-5p was detected to target PUM2, which could exacerbate the inflammatory condition of PDLSCs and lead to differentiation defects.

CONCLUSIONS

miR-299-5p has emerged as a promising diagnostic marker for periodontitis and may attenuate inflammation and contribute to osteogenic differentiation in PDLSCs cells by targeting PUM2.

MicroRNA-27a transfected dental pulp stem cells undergo odonto/osteogenic differentiation via targeting DKK3 and SOSTDC1 in Wnt/BMP signaling in vitro and enhance bone formation in vivo

BACKGROUND

MicroRNAs (miRNAs) play a crucial role in cell differentiation through epigenetic regulation of gene expression. In human dental pulp cells, we have identified miRNA-27a being upregulated under inflammatory conditions. Here, we aimed to examine whether (i) overexpression of miRNA-27a in human dental pulp stem cells (hDPSCs) enhances their odonto/osteoblastic differentiation via Wnt and bone morphogenetic protein signaling; and (ii) hDPSCs overexpressing miRNA-27a promote new bone formation in vivo.

METHODS

hDPSCs were cultured in osteogenic medium to promote differentiation. To examine the role of miRNA-27a, hDPSCs were transfected with either a miRNA-27a mimic to enhance or an inhibitor to suppress miRNA-27a expression. Odonto/osteoblastic differentiation was assessed by evaluating the expression of specific markers, Wnt and bone morphogenetic protein (BMP) signaling molecules, and mineralization capacity using RT-qPCR, western blotting, Alizarin Red S (ARS) staining, and alkaline phosphatase (ALP) activity. Potential miRNA-27a binding sites in the 3'UTRs of DKK3 and SOSTDC1 were identified via bioinformatics analysis and validated through the luciferase reporter assay. In vivo, miRNA-27a-overexpressing hDPSCs were seeded into collagen honeycomb scaffolds and implanted into mouse calvarial bone cavities to assess new bone formation.

RESULTS

MiRNA-27a was highly upregulated in hDPSCs committed to odonto/osteoblastic differentiation. Overexpression of miRNA-27a led to increased expression of odonto/osteoblastic markers and enhanced mineralization capacity, while inhibition of miRNA-27a had the opposite effect. MiRNA-27a targeted DKK3, promoting β-catenin nuclear translocation and inhibiting SOSTDC1, which enhanced SMAD1/5 phosphorylation. Binding sites for miRNA-27a were identified in the 3'UTRs of DKK3 and SOSTDC1. In vivo, miRNA-27a-overexpressing hDPSCs promoted new bone formation in mouse calvaria bone cavities.

CONCLUSION

Transfection of miRNA-27a in hDPSCs enhanced their odonto/osteoblastic differentiation by targeting DKK3 and SOSTDC1, thereby promoting the Wnt and BMP signaling. Transplantation of miRNA-27a-overexpressing hDPSCs promoted new bone formation in vivo. These findings deepen our understanding of the effects of miRNA on Wnt and BMP pathways and suggest a potential clinical application for miRNA-27a in promoting hard tissue regeneration, offering a promising therapeutic target for dental and craniofacial tissue reconstruction.

Emerging roles of extracellular vesicles in oral and maxillofacial areas

The oral and maxillofacial region is a highly complex area composed of multiple tissue types and bears various critical functions of the human body. Diseases in this region pose significant diagnostic and management challenges; therefore, exploring new strategies for early diagnosis, targeted treatment, and tissue reconstruction is key to improving patient prognosis and quality of life. Extracellular vesicles are a group of heterogeneous lipid-bilayer membrane structures secreted by most cell types, including exosomes, microvesicles, and apoptotic bodies. Present in various body fluids and tissues, they act as messengers via the transfer of nucleic acids, proteins, and metabolites to recipient cells. To date, studies have revealed the different roles of extracellular vesicles in physiological or pathological processes, as well as applications in disease diagnosis, prognosis, and treatment. The importance and tissue specificity of the dental and maxillofacial tissues indicate that extracellular vesicles derived from this region are promising for further research. This paper reviews the published data on extracellular vesicles derived from cells, body fluids, and tissues in oral and maxillofacial regions, summarizes the latest advances in extracellular vesicles from extensive sources, and concludes with a focus on the current research progress and application prospects of engineered exosomes in oral science.

KAT3B-mediated succinylation of DERL3 suppresses osteogenic differentiation by promoting M1/M2 macrophage polarization

Periodontitis is a chronic inflammatory disease influenced by macrophage polarization. Additionally, succinylation-enriched Porphyromonas gingivalis is a pathogenic factor of periodontitis. However, the role of succinylation in the pathogenesis of periodontitis remains unclear. This study aimed to investigate the effects of a succinyltransferase KAT3B on macrophage polarization, osteogenic differentiation, and the molecular mechanism. Macrophages RAW264.7 were cocultured with MC3T3-E1-differentiated osteoblasts, and macrophage polarization and osteogenic differentiation were evaluated. iTRAQ-based proteomic analysis identified that DERL3 was highly expressed in lipopolysaccharide (LPS)-treated MC3T3-E1 cells. The TLR4/MyD88 pathway is closely related to inflammatory response. Thus, the succinylation of DERL3 and the TLR4/MyD88 pathway were assessed using immunoblotting. The results showed that KAT3B-mediated succinylation was increased in LPS-treated MC3T3-E1 cells and patients with periodontitis. Knockdown of KAT3B inhibited macrophage M1-like polarization and promoted M2-like polarization, thereby promoting osteogenic differentiation in LPS-treated osteoblasts. Mechanically, overexpression of KAT3B promoted the succinylation of DERL3 and stabilized this protein, thereby upregulating DERL3 expression. Rescue experiments showed that DERL3 reversed the promotion of osteogenic differentiation and M2/M1 macrophage polarization caused by KAT3B knockdown. Moreover, DERL3 activated the TLR4/MyD88 pathway, and inhibition of this pathway reversed macrophage polarization and osteogenesis mediated by DERL3. In vivo experiments showed that KAT3B knockdown attenuated experimental periodontitis in rats. In conclusion, silencing of KAT3B promotes osteogenic differentiation by inducing M2/M1 macrophage polarization through the succinylation DERL3, which regulates the TLR4/MyD88 pathway, thereby attenuating periodontitis. These findings suggest that KAT3B may be a promising therapeutic target for periodontitis.

Mesenchymal stem cell-derived extracellular vesicles in periodontal bone repair

Periodontitis is a chronic inflammatory disease that destroys tooth-supporting structures and poses significant public health challenges due to its high prevalence and links to systemic health conditions. Traditional treatments are effective in reducing the inflammatory response and improving the clinical symptoms of periodontitis. However, these methods are challenging to achieve an ideal treatment effect in alveolar bone repair. Mesenchymal stem cells (MSCs) represent a potential alternative for the treatment of periodontal bone defects due to their self-renewal and differentiation capabilities. Recent research indicates that MSCs exert their effects primarily through paracrine mechanisms. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) serve as pivotal mediators in intercellular communication, transferring microRNAs (miRNAs), messenger RNAs (mRNAs), proteins, and cytokines to recipient cells, thereby emulating the therapeutic effects of MSCs. In periodontitis, MSC-EVs play a pivotal role in immunomodulation and bone remodeling, thereby facilitating periodontal bone repair. As a cell-free therapy, MSC-EVs demonstrate considerable clinical potential due to their specialized membrane structure, minimal immunogenicity, low toxicity, high biocompatibility, and nanoscale size. This review indicates that MSC-EVs represent a promising approach for periodontitis treatment, with the potential to overcome the limitations of traditional therapies and offer a more effective solution for bone repair in periodontal disease. In this review, we introduce MSC-EVs, emphasizing their mechanisms and clinical applications in periodontal bone repair. It synthesizes recent advances, existing challenges, and future prospects to present up-to-date information and novel techniques for periodontal regeneration and to guide the improvement of MSC-EV therapy in clinical practice.

Extracellular Vesicles in Periodontitis: Pathogenic Mechanisms and Therapeutic Potential

Periodontitis is a prevalent yet frequently overlooked oral disease that is linked to a range of systemic conditions. Although basic treatment and periodontal surgery can alleviate the symptoms of periodontitis to a certain extent, the treatment of severe tissue defects or refractory cases is not effective. Extracellular vesicles (EVs) are subcellular lipid bilayer particles that come from a variety of sources and are prevalent in the biological fluids of vertebrates. They play a key role in intercellular communication by transporting multiple signaling molecules. Recent research has indicated that EVs derived from periodontal pathogens can trigger periodontitis, exacerbate the periodontal damage, and potentially disseminate to other parts of the body, leading to systemic conditions. Conversely, extracellular vesicles derived from dental stem cells (DSCs) have demonstrated the ability to regulate the local periodontal immune environment and foster the regeneration and repair of periodontal tissues, positioning them as a promising candidate for cell-free therapeutic approaches to periodontitis. This review aims to summarize the latest research on the involvement of EVs from different sources in the pathogenesis and treatment of periodontitis, especially to systematically elucidate the mechanism of EVs secreted by periodontal pathogens in periodontitis-related systemic diseases for the first time. By uncovering these complex regulatory processes, new and more effective therapeutic approaches can be explored in the battle against periodontitis and its associated systemic diseases.

Dental pulp stem cell-derived intracellular vesicles prevent orthodontic relapse by inhibiting PI3K/Akt/NF-κB-mediated osteoclast activity

BACKGROUND

Orthodontic relapse, the undesired deviation of teeth from their corrected positions, remains a significant challenge in clinical orthodontics. Incomplete periodontal bone remodeling has been identified as a key factor in this process. Despite decades of research, currently there are no effective strategies to prevent relapse.

METHODS

We isolated and identified dental pulp stem cell-derived intracellular vesicles (DPSC-IV) from human dental pulp tissue. To investigate its effect, DPSC-IV was added to osteoblast or osteoclast differentiation medium. During the orthodontic retention period, DPSC-IV was administrated to rats by subgingival injection. Relapse distance and relapse rate were calculated to evaluate DPSC-IV's ability to prevent relapse. Additionally, Western blot analysis were used to examine DPSC-IV's inhibitory effect on osteoclast differentiation.

RESULTS

DPSC-IV significantly promoted osteoblast differentiation and inhibited osteoclast differentiation. Application of DPSC-IV during retention resulted in a significant reduction in both relapse distance and relapse rate, with improved periodontal structure and decreased osteoclast activity. This effect was mediated by the PI3K/Akt/NF-κB signaling pathway and could be reversed by the PI3K activator insulin-like growth factor-1 (IGF-1).

CONCLUSION

This study highlights the potential of DPSC-IV as a novel preventive approach against orthodontic relapse, offering a novel strategy for maintaining long-term orthodontic stability.

Exosomes in Oral Diseases: Mechanisms and Therapeutic Applications

Exosomes, small extracellular vesicles secreted by various cells, play crucial roles in the pathogenesis and treatment of oral diseases. Recent studies have highlighted their involvement in orthodontics, periodontitis, oral squamous cell carcinoma (OSCC), and hand, foot, and mouth disease (HFMD). Exosomes have a positive effect on the inflammatory environment of the oral cavity, remodeling and regeneration of oral tissues, and offer promising therapeutic options for bone and periodontal tissue restoration. In OSCC tumor-derived exosomes promote cancer progression through cell proliferation, migration, invasion, and angiogenesis, and serve as potential biomarkers for early diagnosis and prognosis. Additionally, engineered exosomes constructed specifically based on exosome properties hold great promise for targeted drug delivery and regenerative therapies such as bone regeneration in orthodontics and periodontal healing. With continued research, exosomes hold great potential for improving diagnosis and treatment in oral diseases, advancing personalized and regenerative therapies.

Odontogenic exosomes simulating the developmental microenvironment promote complete regeneration of pulp-dentin complex in vivo

INTRODUCTION

Establishing an optimized regenerative microenvironment for pulp-dentin complex engineering has become increasingly critical. Recently, exosomes have emerged as favorable biomimetic nanotherapeutic tools to simulate the developmental microenvironment and facilitate tissue regeneration.

OBJECTIVES

This study aimed to elucidate the multifaceted roles of exosomes from human dental pulp stem cells (DPSCs) that initiated odontogenic differentiation while sustaining mesenchymal stem cell (MSC) characteristics in odontogenesis, angiogenesis, and neurogenesis during pulp-dentin complex regeneration.

METHODS

Differential centrifugation was performed to isolate exosomes from normal DPSCs (DPSC-Exos) and DPSCs that initially triggered odontogenic differentiation (DPSC-Od-Exos). The impact of these exosomes on the biological behavior of DPSCs and human umbilical vein endothelial cells (HUVECs) was examined in vitro through CCK-8 assay and Transwell migration assay, as well as assays dedicated to assessing odontogenic, angiogenic, and neurogenic capabilities. In vivo, Matrigel plugs and human tooth root fragments incorporating either DPSC-Exos or DPSC-Od-Exos were subcutaneously transplanted into mouse models. Subsequent histological, immunohistochemical, and immunofluorescent analyses were conducted to determine the regenerative outcomes.

RESULTS

DPSC-Exos and DPSC-Od-Exos revealed no remarkable difference in their characteristics. In vitro analyses indicated that DPSC-Od-Exos significantly facilitated the proliferation, migration, and multilineage differentiation of DPSCs compared with DPSC-Exos. Furthermore, DPSC-Od-Exos elicited a more pronounced effect on the tubular structure formation of HUVECs. Consistently, Matrigel plug assays confirmed that DPSC-Od-Exos exhibited superior performance in promoting endothelial differentiation of DPSCs and stimulating angiogenesis in HUVECs. Notably, DPSC-Od-Exos contributed to complete pulp-dentin complex regeneration in human tooth root fragments, characterized by enriched neurovascular structures and a continuous layer of odontoblast-like cells, which extended cytoplasmic projections into the newly formed dentinal tubules.

CONCLUSION

By simulating the developmental microenvironment, multifunctional DPSC-Od-Exos demonstrated promising potential for reconstructing dentin-like tissue, vascular networks, and neural architectures, thereby enhancing our understanding of the therapeutic implications of DPSC-Od-Exos in regenerative endodontic treatment.

Advances in the research of immunomodulatory mechanism of mesenchymal stromal/stem cells on periodontal tissue regeneration

Periodontal disease is a highly prevalent disease worldwide that seriously affects people's oral health, including gingivitis and periodontitis. Although the current treatment of periodontal disease can achieve good control of inflammation, it is difficult to regenerate the periodontal supporting tissues to achieve a satisfactory therapeutic effect. In recent years, due to the good tissue regeneration ability, the research on Mesenchymal stromal/stem cells (MSCs) and MSC-derived exosomes has been gradually deepened, especially its ability to interact with the microenvironment of the body in the complex immunoregulatory network, which has led to many new perspectives on the therapeutic strategies for many diseases. This paper systematically reviews the immunomodulatory (including bone immunomodulation) properties of MSCs and their role in the periodontal inflammatory microenvironment, summarizes the pathways and mechanisms by which MSCs and MSC-EVs have promoted periodontal regeneration in recent years, lists potential areas for future research, and describes the issues that should be considered in future basic research and the direction of development of "cell-free therapies" for periodontal regeneration.

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.

Revolutionizing medicine: recent developments and future prospects in stem-cell therapy

Stem-cell therapy is a revolutionary frontier in modern medicine, offering enormous capacity to transform the treatment landscape of numerous debilitating illnesses and injuries. This review examines the revolutionary frontier of treatments utilizing stem cells, highlighting the distinctive abilities of stem cells to undergo regeneration and specialized cell differentiation into a wide variety of phenotypes. This paper aims to guide researchers, physicians, and stakeholders through the intricate terrain of stem-cell therapy, examining the processes, applications, and challenges inherent in utilizing stem cells across diverse medical disciplines. The historical journey from foundational contributions in the late 19th and early 20th centuries to recent breakthroughs, including ESC isolation and iPSC discovery, has set the stage for monumental leaps in medical science. Stem cells' regenerative potential spans embryonic, adult, induced pluripotent, and perinatal stages, offering unprecedented therapeutic opportunities in cancer, neurodegenerative disorders, cardiovascular ailments, spinal cord injuries, diabetes, and tissue damage. However, difficulties, such as immunological rejection, tumorigenesis, and precise manipulation of stem-cell behavior, necessitate comprehensive exploration and innovative solutions. This manuscript summarizes recent biotechnological advancements, critical trial evaluations, and emerging technologies, providing a nuanced understanding of the triumphs, difficulties, and future trajectories in stem cell-based regenerative medicine. Future directions, including precision medicine integration, immune modulation strategies, advancements in gene-editing technologies, and bioengineering synergy, offer a roadmap in stem cell treatment. The focus on stem-cell therapy's potential highlights its significant influence on contemporary medicine and points to a future in which individualized regenerative therapies will alleviate various medical disorders.

Dental Pulp Stem Cell Lysate-Based Hydrogel Improves Diabetic Wound Healing via the Regulation of Anti-Inflammatory Macrophages and Keratinocytes

The prolonged existence of chronic wounds heightens the risk of patients experiencing chronic pain, necrosis, and amputation. Dental pulp stem cells (DPSCs) have garnered attention due to their potential immunomodulatory and tissue repair regenerative effects in the management of chronic wounds. However, stem-cell-based therapy faces challenges such as malignant differentiation, immune rejection, and long-term effectiveness. To overcome these challenges, we proposed a chronic wound therapy using a hydrogel derived from human-originated dental pulp stem cell lysate (DPSCL). Our data indicate that, with the degradation of the dental pulp stem cell lysate-based hydrogel (DPSCLH), the slowly released cell lysates recruit anti-inflammatory M2 macrophages and promote the proliferation, migration, and keratinization of HacaT cells. In addition, in vivo studies revealed that DPSCLH avoids immune rejection reactions and induces a long-term accumulation of endogenous M2 macrophages. In a mouse model of diabetic wounds, DPSCLH effectively modulates the inflammatory microenvironment around diabetic wounds, promotes the formation of the stratum corneum, and facilitates the healing of wounds, thus holding tremendous potential for the treatment of diabetic wounds.

Conditioned Extracellular Vesicles Derived from Dedifferentiated Fat Cells Promote Bone Regeneration by Altering MicroRNAs

Background: Extracellular vesicles (EVs) derived from stem cells demonstrate significant potential in bone regeneration. Adipose tissue is regarded as a stem cell reservoir with abundant reserves and easy accessibility. Compared to adipose-derived stem cells (ASCs), dedifferentiated fat cells (DFATs) possess similar stem cell characteristics but exhibit greater proliferative capacity, higher homogeneity, and an enhanced osteogenic differentiation potential. This study is the first to examine the effect of DFATs-derived EVs on bone regeneration and elucidate their potential mechanisms of action. Methods: Primary DFATs were cultured using the "ceiling culture" method and EVs were isolated by ultracentrifugation and characterized. Experiments were performed to assess the impact of the EVs on the proliferation, migration, and osteogenesis of bone marrow mesenchymal stem cells (BMSCs). Subsequently, high-throughput miRNA sequencing was conducted on the EVs derived from DFATs that had undergone 0 days (0d-EVs) and 14 days (14d-EVs) of osteogenic differentiation. Results: The results indicated that the EVs derived from DFATs which experienced 14 days of osteogenic induction significantly promoted the proliferation, migration, and osteogenic differentiation of BMSCs. High-throughput sequencing results revealed that up-regulated miRNAs in the 14d-EVs were primarily involved in biological processes such as the Notch signaling pathway and the positive regulation of cell movement and migration. The target genes of these differently expressed miRNAs were enriched in osteogenesis-related signaling pathways. Conclusion: This study innovatively demonstrated that conditioned EVs (14d-EVs) derived from DFATs promoted the osteogenic differentiation of BMSCs via miRNAs, offering a promising cell-free therapeutic option for bone defect.

Zinc and melatonin mediated antimicrobial, anti-inflammatory, and antioxidant coatings accelerate bone defect repair

Inflammation and bacterial infection are important causes of implant failure, and the development of multifunctional titanium surfaces to address these issues is an effective means of treating infected bone defects. In this study, polyphenols (EGCG) and Zn2+ were first loaded onto the titanium surface to construct an EGCG/Zn2+ polyphenol metal network coating. Then melatonin (MT) was loaded into the EGCG/Zn2+ network structure to prepare the EGCG/Zn2+/MT composite coating. The results proved that the EGCG/Zn2+/MT coating had good mechanical properties, hydrophilicity, corrosion resistance and bioactivity. In vitro, the inhibition rates of EGCG/Zn2+/MT against E. coli and S. aureus were about 97 % and 81 %, respectively. In vitro experiments revealed that EGCG/Zn2+/MT could regulate the polarization of macrophages (RAW264.7) to M2 type, could induce vascularization of human umbilical vein endothelial cells (HUVEC), and could promote the differentiation of pro-osteoblasts (MC3T3-E1) to osteogenesis. Meanwhile, EGCG/Zn2+/MT achieved effective ROS scavenging within HUVEC and MC3T3-E1. In vivo experiments demonstrated that the EGCG/Zn2+/MT coatings possessed favorable biosafety, anti-inflammatory, antimicrobial, and bone repair capabilities. This study provides a simple and versatile strategy for designing multifunctional surfaces with both antimicrobial, anti-inflammatory, antioxidant, angiogenic and osteogenic properties.

Exosome-Laden Hydrogels as Promising Carriers for Oral and Bone Tissue Engineering: Insight into Cell-Free Drug Delivery

Mineralization is a key biological process that is required for the development and repair of tissues such as teeth, bone and cartilage. Exosomes (Exo) are a subset of extracellular vesicles (~50-150 nm) that are secreted by cells and contain genetic material, proteins, lipids, nucleic acids, and other biological substances that have been extensively researched for bone and oral tissue regeneration. However, Exo-free biomaterials or exosome treatments exhibit poor bioavailability and lack controlled release mechanisms at the target site during tissue regeneration. By encapsulating the Exos into biomaterials like hydrogels, these disadvantages can be mitigated. Several tissue engineering approaches, such as those for wound healing processes in diabetes mellitus, treatment of osteoarthritis (OA) and cartilage degeneration, repair of intervertebral disc degeneration, and cardiovascular diseases, etc., have been exploited to deliver exosomes containing a variety of therapeutic and diagnostic cargos to target tissues. Despite the significant efficacy of Exo-laden hydrogels, their use in mineralized tissues, such as oral and bone tissue, is very sparse. This review aims to explore and summarize the literature related to the therapeutic potential of hydrogel-encapsulated exosomes for bone and oral tissue engineering and provides insight and practical procedures for the development of future clinical techniques.

Mesenchymal stem cell-derived exosomes: a potential cell-free therapy for orthodontic tooth stability management

Orthodontic relapse (OR) occurs at a rate of over 70%. Retention is the current attempt at prevention, but it requires a considerable amount of time and cannot fully block OR. It's imperative to find a safe and effective method for managing post-orthodontic tooth stability. Periodontal bone remodeling is one crucial biological foundation of OR. Mesenchymal stem cell-derived exosomes (MSC-Exo) show promise in relapse management by regulating periodontal bone remodeling. MSC-Exo can prevent relapse by regulating periodontal ligament function, osteoclast activity, osteoblast differentiation, macrophage polarization, and periodontal microcirculation. In recent years, exosome-loaded hydrogels, which achieve controlled exosome release, have demonstrated efficacy in promoting bone regeneration and remodeling, offering promising prospects for OR management. This review aims to highlight the use of MSC-Exo-based therapy for preventing OR, offering new insights for future research focused on improving tooth stability and enhancing orthodontic anchorage.

M2 macrophage-derived exosomes enable osteogenic differentiation and inhibit inflammation in human periodontal ligament stem cells through promotion of CXCL12 expression

BACKGROUND

Periodontitis is a dental disease characterized by inflammation of periodontal tissues and loss of the periodontal ligaments and alveolar bone. Exosomes are a class of extracellular vesicles that are involved in a variety of diseases by releasing active substances. In this study, we aimed to investigate the effect and mechanism of exosomes from M2 polarized macrophages (M2-exos) on osteogenic differentiation in human periodontal ligament stem cells (hPDLSCs).

METHODS

M2-exos were isolated from IL-4-induced RAW264.7 cells (M2 macrophages) and then treated on hPDLSCs. Osteogenic differentiation was assessed by alkaline phosphatase (ALP) staining, alizarin red S (ARS) staining, measurement of osteogenic differentiation-related genes and proteins, and inflammation was evaluated by measuring the levels of inflammatory factors. The mechanism of M2-exo was confirmed through qPCR, western blot, ALP and ARS staining.

RESULTS

Results suggested that M2-exo improved osteogenic differentiation and inhibited inflammation in LPS-induced hPDLSCs. CXCL12 expression was elevated in M2 macrophages, but decreased in LPS-induced hPDLSCs. Moreover, the effect of M2-exo on osteogenic differentiation and inflammation in LPS-induced hPDLSCs was reversed by CXCL12 knockdown.

CONCLUSION

We demonstrated that M2-exo facilitated osteogenic differentiation and suppressed inflammation in LPS-induced hPDLSCs through promotion of CXCL12 expression. These results suggested the potential of M2-exo in the treatment of periodontitis, which may provide a new theoretical basis for M2-exo treatment of periodontitis.

Mesenchymal stem cells and their extracellular vesicles in bone and joint diseases: targeting the NLRP3 inflammasome

The nucleotide-binding oligomerization domain-like-receptor family pyrin domain-containing 3 (NLRP3) inflammasome is a cytosolic multi-subunit protein complex, and recent studies have demonstrated the vital role of the NLRP3 inflammasome in the pathological and physiological conditions, which cleaves gasdermin D to induce inflammatory cell death called pyroptosis and mediates the release of interleukin-1 beta and interleukin-18 in response to microbial infection or cellular injury. Over-activation of the NLRP3 inflammasome is associated with the pathogenesis of many disorders affecting bone and joints, including gouty arthritis, osteoarthritis, rheumatoid arthritis, osteoporosis, and periodontitis. Moreover, mesenchymal stem cells (MSCs) have been discovered to facilitate the inhibition of NLRP3 and maybe ideal for treating bone and joint diseases. In this review, we implicate the structure and activation of the NLRP3 inflammasome along with the detail on the involvement of NLRP3 inflammasome in bone and joint diseases pathology. In addition, we focused on MSCs and MSC-extracellular vesicles targeting NLRP3 inflammasomes in bone and joint diseases. Finally, the existing problems and future direction are also discussed.

Multi-site enhancement of osteogenesis: peptide-functionalized GelMA hydrogels with three-dimensional cultures of human dental pulp stem cells

Human dental pulp stem cells (hDPSCs) have demonstrated greater proliferation and osteogenic differentiation potential in certain studies compared to other types of mesenchymal stem cells, making them a promising option for treating craniomaxillofacial bone defects. However, due to low extracting concentration and long amplifying cycles, their access is limited and utilization rates are low. To solve these issues, the principle of bone-forming peptide-1 (BFP1) in situ chemotaxis was utilized for the osteogenic differentiation of hDPSCs to achieve simultaneous and synergistic osteogenesis at multiple sites. BFP1-functionalized gelatin methacryloyl hydrogel provided a 3D culture microenvironment for stem cells. The experimental results showed that the 3D composite hydrogel scaffold constructed in this study increased the cell spread area by four times compared with the conventional GelMA scaffold. Furthermore, the problems of high stem cell dosage and low rate of utilization were alleviated by orchestrating the programmed proliferation and osteogenic differentiation of hDPSCs. In vivo, high-quality repair of critical bone defects was achieved using hDPSCs extracted from a single tooth, and multiple 'bone island'-like structures were successfully observed that rapidly induced robust bone regeneration. In conclusion, this study suggests that this kind of convenient, low-cost, island-like osteogenesis strategy involving a low dose of hDPSCs has great potential for repairing craniomaxillofacial critical-sized bone defects.

Jaw osteoporosis: Challenges to oral health and emerging perspectives of treatment

Osteoporosis is a prevalent bone metabolic disease that poses a significant challenge to global human health. Jaw osteoporosis, characterized by microstructural damage of the jaw resulting from various factors, is one of the common manifestations of this condition. Recent studies have demonstrated that jaw osteoporosis has multifaceted effects on oral health and can negatively impact conditions such as periodontitis, oral implantation, orthodontic treatment, and wound healing. However, there are still some limitations in the conventional treatment of osteoporosis. For instance, while bisphosphonates can enhance bone quality, they may also lead to osteonecrosis of the jaw, which poses a potential safety hazard in oral diagnosis and treatment. In recent years, considerable attention has been focused on improving the pathological condition of jaw osteoporosis. Treatment strategies such as gut microbial regulation, extracellular vesicles, molecular targeted therapy, herbal medicine, mechanical stimulation are expected to enhance efficacy and minimize adverse reactions. Therefore, understanding these effects and exploring novel treatments for jaw osteoporosis may provide new insights for oral health maintenance and disease treatment. This article reviews the impact of jaw osteoporosis on oral health and describes the limitations associated with current methods. It also discusses emerging perspectives on treatment, offering a comprehensive overview of the challenges and future directions in managing jaw osteoporosis.

Different origin-derived exosomes and their clinical advantages in cancer therapy

Exosomes, as a class of small extracellular vesicles closely related to the biological behavior of various types of tumors, are currently attracting research attention in cancer diagnosis and treatment. Regarding cancer diagnosis, the stability of their membrane structure and their wide distribution in body fluids render exosomes promising biomarkers. It is expected that exosome-based liquid biopsy will become an important tool for tumor diagnosis in the future. For cancer treatment, exosomes, as the "golden communicators" between cells, can be designed to deliver different drugs, aiming to achieve low-toxicity and low-immunogenicity targeted delivery. Signaling pathways related to exosome contents can also be used for safer and more effective immunotherapy against tumors. Exosomes are derived from a wide range of sources, and exhibit different biological characteristics as well as clinical application advantages in different cancer therapies. In this review, we analyzed the main sources of exosomes that have great potential and broad prospects in cancer diagnosis and therapy. Moreover, we compared their therapeutic advantages, providing new ideas for the clinical application of exosomes.

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.

Apoptotic Vesicles Derived from Dental Pulp Stem Cells Promote Bone Formation through the ERK1/2 Signaling Pathway

Osteoporosis is a common degenerative bone disease. The treatment of osteoporosis remains a clinical challenge in light of the increasing aging population. Human dental pulp stem cells (DPSCs), a type of mesenchymal stem cells (MSCs), are easy to obtain and have a high proliferation ability, playing an important role in the treatment of osteoporosis. However, MSCs undergo apoptosis within a short time when used in vivo; therefore, apoptotic vesicles (apoVs) have attracted increasing attention. Currently, the osteogenic effect of DPSC-derived apoVs is unknown; therefore, this study aimed to determine the role of DPSC-derived apoVs and their potential mechanisms in bone regeneration. We found that MSCs could take up DPSC-derived apoVs, which then promoted MSC osteogenesis in vitro. Moreover, apoVs could increase the trabecular bone count and bone mineral density in the mouse osteoporosis model and could promote bone formation in rat cranial defects in vivo. Mechanistically, apoVs promoted MSC osteogenesis by activating the extracellular regulated kinase (ERK)1/2 signaling pathway. Consequently, we propose a novel therapy comprising DPSC-derived apoVs, representing a promising approach to treat bone loss and bone defects.

Exosomes as Promising Therapeutic Tools for Regenerative Endodontic Therapy

Pulpitis is a common and frequent disease in dental clinics. Although vital pulp therapy and root canal treatment can stop the progression of inflammation, they do not allow for genuine structural regeneration and functional reconstruction of the pulp-dentin complex. In recent years, with the development of tissue engineering and regenerative medicine, research on stem cell-based regenerative endodontic therapy (RET) has achieved satisfactory preliminary results, significantly enhancing its clinical translational prospects. As one of the crucial paracrine effectors, the roles and functions of exosomes in pulp-dentin complex regeneration have gained considerable attention. Due to their advantages of cost-effectiveness, extensive sources, favorable biocompatibility, and high safety, exosomes are considered promising therapeutic tools to promote dental pulp regeneration. Accordingly, in this article, we first focus on the biological properties of exosomes, including their biogenesis, uptake, isolation, and characterization. Then, from the perspectives of cell proliferation, migration, odontogenesis, angiogenesis, and neurogenesis, we aim to reveal the roles and mechanisms of exosomes involved in regenerative endodontics. Lastly, immense efforts are made to illustrate the clinical strategies and influencing factors of exosomes applied in dental pulp regeneration, such as types of parental cells, culture conditions of parent cells, exosome concentrations, and scaffold materials, in an attempt to lay a solid foundation for exploring and facilitating the therapeutic strategy of exosome-based regenerative endodontic procedures.

Understanding exosomes: Part 3-therapeutic + diagnostic potential in dentistry

Exosomes are the smallest subset of extracellular signaling vesicles secreted by most cells with the ability to communicate with other tissues and cell types over long distances. Their use in regenerative medicine has gained tremendous momentum recently due to their ability to be utilized as therapeutic options for a wide array of various diseases. Over 5000 publications are currently being published on this topic yearly, many of which in the dental space. This extensive review article is the first scoping review aimed at summarizing all therapeutic uses of exosomes in regenerative dentistry. A total of 944 articles were identified as using exosomes in the dental field for either their regenerative/therapeutic potential or for diagnostic purposes derived from the oral cavity. In total, 113 research articles were selected for their regenerative potential (102 in vitro, 60 in vivo, 50 studies included both). Therapeutic exosomes were most commonly derived from dental pulps, periodontal ligament cells, gingival fibroblasts, stem cells from exfoliated deciduous teeth, and the apical papilla which have all been shown to facilitate the regenerative potential of a number of tissues including bone, cementum, the periodontal ligament, nerves, aid in orthodontic tooth movement, and relieve temporomandibular joint disorders, among others. Results demonstrate that the use of exosomes led to positive outcomes in 100% of studies. In the bone field, exosomes were found to perform equally as well or better than rhBMP2 while significantly reducing inflammation. Periodontitis animal models were treated with simple gingival injections of exosomes and benefits were even observed when the exosomes were administered intravenously. Exosomes are much more stable than growth factors and were shown to be far more resistant against degradation by periodontal pathogens found routinely in a periodontitis environment. Comparative studies in the field of periodontal regeneration found better outcomes for exosomes even when compared to their native parent stem cells. In total 47 diagnostic studies revealed a role for salivary/crevicular fluid exosomes for the diagnosis of birth defects, cardiovascular disease, diabetes, gingival recession detection, gingivitis, irritable bowel syndrome, neurodegenerative disease, oral lichen planus, oral squamous cell carcinoma, oropharyngeal cancer detection, orthodontic root resorption, pancreatic cancer, periodontitis, peri-implantitis, Sjögren syndrome, and various systemic diseases. Hence, we characterize the exosomes as possessing "remarkable" potential, serving as a valuable tool for clinicians with significant advantages.

The Genetic Aspects of Periodontitis Pathogenesis and the Regenerative Properties of Stem Cells

Periodontitis (PD) is a prevalent and chronic inflammatory disease with a complex pathogenesis, and it is associated with the presence of specific pathogens, such as Porphyromonas gingivalis. Dysbiosis and dysregulated immune responses ultimately lead to chronic inflammation as well as tooth and alveolar bone loss. Multiple studies have demonstrated that genetic polymorphisms may increase the susceptibility to PD. Furthermore, gene expression is modulated by various epigenetic mechanisms, such as DNA methylation, histone modifications, or the activity of non-coding RNA. These processes can also be induced by PD-associated pathogens. In this review, we try to summarize the genetic processes that are implicated in the pathogenesis of PD. Furthermore, we discuss the use of these mechanisms in diagnosis and therapeutic purposes. Importantly, novel treatment methods that could promote tissue regeneration are greatly needed in PD. In this paper, we also demonstrate current evidence on the potential use of stem cells and extracellular vesicles to stimulate tissue regeneration and suppress inflammation. The understanding of the molecular mechanisms involved in the pathogenesis of PD, as well as the impact of PD-associated bacteria and stem cells in these processes, may enhance future research and ultimately improve long-term treatment outcomes.

Mesenchymal stem cell-derived apoptotic bodies alleviate alveolar bone destruction by regulating osteoclast differentiation and function

Periodontitis is caused by overactive osteoclast activity that results in the loss of periodontal supporting tissue and mesenchymal stem cells (MSCs) are essential for periodontal regeneration. However, the hypoxic periodontal microenvironment during periodontitis induces the apoptosis of MSCs. Apoptotic bodies (ABs) are the major product of apoptotic cells and have been attracting increased attention as potential mediators for periodontitis treatment, thus we investigated the effects of ABs derived from MSCs on periodontitis. MSCs were derived from bone marrows of mice and were cultured under hypoxic conditions for 72 h, after which ABs were isolated from the culture supernatant using a multi-filtration system. The results demonstrate that ABs derived from MSCs inhibited osteoclast differentiation and alveolar bone resorption. miRNA array analysis showed that miR-223-3p is highly enriched in those ABs and is critical for their therapeutic effects. Targetscan and luciferase activity results confirmed that Itgb1 is targeted by miR-223-3p, which interferes with the function of osteoclasts. Additionally, DC-STAMP is a key regulator that mediates membrane infusion. ABs and pre-osteoclasts expressed high levels of DC-STAMP on their membranes, which mediates the engulfment of ABs by pre-osteoclasts. ABs with knock-down of DC-STAMP failed to be engulfed by pre-osteoclasts. Collectively, MSC-derived ABs are targeted to be engulfed by pre-osteoclasts via DC-STAMP, which rescued alveolar bone loss by transferring miR-223-3p to osteoclasts, which in turn led to the attenuation of their differentiation and bone resorption. These results suggest that MSC-derived ABs are promising therapeutic agents for the treatment of periodontitis.