The Experimental Study of Periodontal Ligament Stem Cells Derived Exosomes with Hydrogel Accelerating Bone Regeneration on Alveolar Bone Defect

Comparative Dental Pulp Stem Cells (DPSCs) and Periodontal Ligament Stem Cells (PDLSCs): Difference in effect of aspirin on osteoblast potential of PDLSCs and DPSCs

Periodontal Ligament Stem Cells (PDLSCs) and Dental Pulp Stem Cells (DPSCs) are mesenchymal stem cells with the ability to self-renew and differentiate into three lineages. One significant advantage of dental stem cells, such as PDLSCs and DPSCs, is their ease of harvest compared to other types of mesenchymal stem cells (MSCs). While MSCs are highly valued in bone tissue engineering, MSCs sourced from dental tissues, such as PDLSCs and DPSCs, offer promising options for periodontal regeneration because they are more easily accessible and can be collected through minimally invasive methods. Currently, PDLSCs and DPSCs exhibit a strong ability to undergo osteogenic differentiation when stimulated by factors such as growth factors, chemicals, and paracrine signaling. It has been shown that aspirin (ASA) can enhance the osteoblastic potential of PDLSCs and DPSCs, although the exact mechanism remains unclear. This article examines the origin and features of mesenchymal stem cells, the bone regeneration potential of DPSCs and PDLSCs, the factors that enhance their osteogenic differentiation, and a comparison of PDLSCs and DPSCs regarding their proliferation and differentiation abilities. Additionally, we will examine the effects of aspirin on PDLSCs and DPSCs. In conclusion, PDLSCs show a greater effect on osteoblast differentiation.

Role of exosomes in dental and craniofacial regeneration - A review

BACKGROUND

The treatment of congenital deformities, traumatic injuries, infectious diseases, and tumors in the craniomaxillofacial (CMF) region is complex due to the intricate nature of the tissues involved. Conventional treatments such as bone grafts and cell transplantation face limitations, including the need for multiple surgeries, complications, and safety concerns.

OBJECTIVE

This paper aims to provide a comprehensive analysis of the role of exosomes (EXOs) in CMF and dental tissue regeneration and to explore their potential applications in regenerative dental medicine.

METHODS

An extensive review of advancements in tissue engineering, materials sciences, and nanotechnology was conducted to evaluate the development of delivery systems for EXOs-based therapies. The analysis included how EXOs, as nanovesicles released by cells, can be modified to target specific cells or loaded with functional molecules for drug or gene delivery.

RESULTS

EXOs have emerged as a promising alternative to cell transplant therapy, offering a safer method for cell communication and epigenetic control. EXOs transport important proteins and genetic materials, facilitating intercellular communication and delivering therapeutics effectively. The potential of EXOs in personalized medicine, particularly in diagnosing, customizing treatment, and predicting patient responses, is highlighted.

CONCLUSION

EXO-mediated therapy holds significant potential for advancing tissue regeneration, offering targeted, personalized treatment options with reduced side effects. However, challenges in purification, production, and standardized protocols need to be addressed before its clinical application can be fully realized.

Polydopamine-functionalized nanohydroxyapatite coated exosomes with enhanced cytocompatibility and osteogenesis for bone regeneration

BackgroundMesenchymal stem cells-derived exosomes, crucial in regenerative medicine, have been explored for their potential for the functional modification of bone scaffolds.ObjectiveTo design a functionally modified biomimetic nanohydroxyapatite using exosomes and explore its effects on bone regeneration.MethodsA biomimetic nanohydroxyapatite (named as tHA) was fabricated as previous methods using a polydopamine (pDA) structure as a template, and exosomes (Exo) derived from periodontal ligament stem cells (PDLSCs) were used to functionally modify the tHA scaffold material through pDA. The effects of functional composite scaffold (tHA-Exo) on cells proliferation and osteogenic differentiation were investigated. Furthermore, their effect on bone regeneration was also evaluated in vivo.ResultsExosomes can be loaded onto the tHA via pDA and the tHA-Exo releases exosomes in a sustained and stable manner. tHA-Exo showed improved cytocompatibility compared to controls. Additionally, tHA-Exo significantly enhanced the proliferation and osteogenic differentiation of PDLSCs. More importantly, animal experiments have shown that tHA-Exo could dramatically promote bone regeneration.ConclusionThe tHA nanoparticles, functionally modified by the PDLSCs-Exo through pDA, significantly promoted bone regeneration by improving its cytocompatibility and osteogenic potential, which could serve as a promising material for promoting bone regeneration.

Low-intensity pulsed ultrasound enhances the osteogenic potential of PDLSCs-derived extracellular vesicles through COMP/PI3K/AKT

The therapeutic potential of extracellular vesicles (EVs) in bone regeneration is noteworthy; however, their clinical application is impeded by low yield and limited efficacy. This study investigated the effect of low-intensity pulsed ultrasound (LIPUS) on the therapeutic efficacy of EVs derived from periodontal ligament stem cells (PDLSCs) and preliminarily explored its mechanism. PDLSCs were cultured with osteogenic media and stimulated with or without LIPUS, and then EVs and LIPUS-stimulated EVs (L-EVs) were isolated separately. We investigated the biological characteristics and effects of these two EVs on cell proliferation, migration, osteogenic differentiation, and bone regeneration in vivo and in vitro, and explored the potential mechanism by analyzing protein profiles. LIPUS significantly stimulated the secretion of PDLSCs-EVs, and L-EVs exhibited stronger efficacy in promoting cell proliferation, migration, and osteogenic differentiation, thereby enhancing new bone formation. LIPUS stimulation affected the protein profile of PDLSCs-EVs, and 42 proteins were upregulated and 4 proteins downregulated in L-EVs when compared with EVs. LIPUS significantly upregulated the level of cartilage oligomeric matrix protein (COMP) in EVs, which enhanced EVs' osteogenic ability via the PI3K/AKT pathway. This study proposes that LIPUS has potential as an optimization method for enhancing the therapeutic effects of EVs in tissue regeneration.

Hydrogels in Alveolar Bone Regeneration

Alveolar bone defects caused by oral trauma, alveolar fenestration, periodontal disease, and congenital malformations can severely affect oral function and facial aesthetics. Despite the successful clinical applications of bone grafts or bone substitutes, optimal alveolar bone regeneration continues to be challenging due to the complex oral environment and its unique physiological functions. Hydrogels that serve as promising candidates for tissue regeneration are under development to meet the specific needs for increased bone regeneration capacity and improved operational efficiency in alveolar bone repair. In this review, we emphasize the considerations in hydrogel design for alveolar bone regeneration and summarize the latest applications of hydrogels in prevalent clinical diseases related to alveolar bone defects. The future perspectives and challenges for the application of hydrogels in the field of alveolar bone regeneration are also discussed. Deepening our understanding of these biomaterials will facilitate the advent of novel inventions to improve the outcome of alveolar bone tissue regeneration.

Recent Strategies and Advances in Hydrogel-Based Delivery Platforms for Bone Regeneration

Bioactive molecules have shown great promise for effectively regulating various bone formation processes, rendering them attractive therapeutics for bone regeneration. However, the widespread application of bioactive molecules is limited by their low accumulation and short half-lives in vivo. Hydrogels have emerged as ideal carriers to address these challenges, offering the potential to prolong retention times at lesion sites, extend half-lives in vivo and mitigate side effects, avoid burst release, and promote adsorption under physiological conditions. This review systematically summarizes the recent advances in the development of bioactive molecule-loaded hydrogels for bone regeneration, encompassing applications in cranial defect repair, femoral defect repair, periodontal bone regeneration, and bone regeneration with underlying diseases. Additionally, this review discusses the current strategies aimed at improving the release profiles of bioactive molecules through stimuli-responsive delivery, carrier-assisted delivery, and sequential delivery. Finally, this review elucidates the existing challenges and future directions of hydrogel encapsulated bioactive molecules in the field of bone regeneration.

Exosome-Integrated Hydrogels for Bone Tissue Engineering

Exosome-integrated hydrogels represent a promising frontier in bone tissue engineering, leveraging the unique biological properties of exosomes to enhance the regenerative capabilities of hydrogels. Exosomes, as naturally occurring extracellular vesicles, carry a diverse array of bioactive molecules that play critical roles in intercellular communication and tissue regeneration. When combined with hydrogels, these exosomes can be spatiotemporally delivered to target sites, offering a controlled and sustained release of therapeutic agents. This review aims to provide a comprehensive overview of the recent advancements in the development, engineering, and application of exosome-integrated hydrogels for bone tissue engineering, highlighting their potential to overcome current challenges in tissue regeneration. Furthermore, the review explores the mechanistic pathways by which exosomes embedded within hydrogels facilitate bone repair, encompassing the regulation of inflammatory pathways, enhancement of angiogenic processes, and induction of osteogenic differentiation. Finally, the review addresses the existing challenges, such as scalability, reproducibility, and regulatory considerations, while also suggesting future directions for research in this rapidly evolving field. Thus, we hope this review contributes to advancing the development of next-generation biomaterials that synergistically integrate exosome and hydrogel technologies, thereby enhancing the efficacy of bone tissue regeneration.

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.

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.

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.

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.

Metformin enhances the therapeutic effects of extracellular vesicles derived from human periodontal ligament stem cells on periodontitis

Metformin has shown outstanding anti-inflammatory and osteogenic abilities. Mesenchymal stem cell-derived extracellular vesicles (EVs) reveal promising therapeutic potency by carrying various biomolecules. This study explored the effects of metformin on the therapeutic potential of EVs derived from human periodontal ligament stem cells (PDLSCs) for periodontitis. PDLSCs were cultured in osteogenic medium with or without metformin, and the supernatant was then collected separately to extract EVs and metformin-treated EVs (M-EVs). After identifying the characteristics, we evaluated the anti-inflammatory and osteogenic effects of EVs and M-EVs in vivo and in vitro. Osteogenic differentiation of PDLSCs was markedly enhanced after metformin treatment, and the effect was dramatically inhibited by GW4896, an inhibitor of EVs' secretion. Metformin significantly increased EVs' yields and improved their effects on cell proliferation, migration, and osteogenic differentiation. Moreover, metformin significantly enhanced the osteogenic ability of EVs on inflammatory PDLSCs. Animal experiments revealed that alveolar bone resorption was dramatically reduced in the EVs and M-EVs groups when compared to the periodontitis group, while the M-EVs group showed the lowest levels of alveolar bone loss. Metformin promoted the osteogenic differentiation of PDLSCs partly through EVs pathway and significantly enhanced the secretion of PDLSCs-EVs with superior pro-osteogenic and anti-inflammatory potential, thus improving EVs' therapeutic potential on periodontitis.

Hydrogel-exosome system in tissue engineering: A promising therapeutic strategy

Characterized by their pivotal roles in cell-to-cell communication, cell proliferation, and immune regulation during tissue repair, exosomes have emerged as a promising avenue for "cell-free therapy" in clinical applications. Hydrogels, possessing commendable biocompatibility, degradability, adjustability, and physical properties akin to biological tissues, have also found extensive utility in tissue engineering and regenerative repair. The synergistic combination of exosomes and hydrogels holds the potential not only to enhance the efficiency of exosomes but also to collaboratively advance the tissue repair process. This review has summarized the advancements made over the past decade in the research of hydrogel-exosome systems for regenerating various tissues including skin, bone, cartilage, nerves and tendons, with a focus on the methods for encapsulating and releasing exosomes within the hydrogels. It has also critically examined the gaps and limitations in current research, whilst proposed future directions and potential applications of this innovative approach.

Superoxide dismutase 2 scavenges ROS to promote osteogenic differentiation of human periodontal ligament stem cells by regulating Smad3 in alveolar bone-defective rats

BACKGROUND

Osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) is an essential event in alveolar bone regeneration. Oxidative stress may be the main inhibiting factor of hPDLSC osteogenesis. Superoxide dismutase 2 (SOD2) is a key antioxidant enzyme, but its effect on hPDLSC osteogenic differentiation is unclear.

METHODS

Several surface markers were detected by flow cytometry, and the differentiation potential of hPDLSCs was validated by alkaline phosphatase (ALP), Alizarin Red S, and Oil Red O staining. Osteogenic indicators of hPDLSCs were detected by real-time quantitative polymerase chain reaction (RT-qPCR), Western blotting, and ALP staining. Furthermore, alveolar bone defect rat models were analyzed through micro-CT, hematoxylin and eosin, and Masson staining. The intracellular reactive oxygen species (ROS) level was evaluated by a ROS assay kit. Finally, the expression of SOD2, Smad3, and p-Smad3 in hPDLSCs was detected by RT-qPCR and Western blotting (WB).

RESULTS

SOD2 positively regulated the gene and protein expressions of ALP, BMP6, and RUNX2 in hPDLSCs (p < 0.05). Ideal bone formation and continuous cortical bone were obtained by transplanting LV-SOD2 hPDLSCs (lentivirus vector for overexpressing SOD2 in hPDLSCs) in vivo. Exogenous H2O2 downregulated osteogenic indicators (ALP, BMP6, RUNX2) in hPDLSCs (p < 0.05); this was reversed by overexpression of SOD2. WB results showed that the Smad3 and p-Smad3 signaling pathways participated in the osteogenic process of SOD2 in hPDLSCs.

CONCLUSION

SOD2 positively regulated hPDLSC osteogenic differentiation in vitro and in vivo. Mechanistically, SOD2 promotes hPDLSC osteogenic differentiation by regulating the phosphorylation of Smad3 to scavenge ROS. This work provides a theoretical basis for the treatment of alveolar bone regeneration.

The Influence of Orthodontic Treatment on Periodontal Health between Challenge and Synergy: A Narrative Review

By correctly repositioning teeth, orthodontic therapy improves both the function and appearance of an occlusion. The relationship between teeth and the tissues that surround and support them significantly influences these alterations. With ever more adults seeking orthodontic care, orthodontists are increasingly seeing patients with periodontal issues. Concerns about the patient's appearance, such as uneven gingival margins or functional issues caused by inflammatory periodontal diseases, should be accounted for when designing orthodontic treatment plans. Furthermore, orthodontics may increase the chances of saving and recovering a degraded dentition in cases of severe periodontitis. Today, general dentists, dontists, and orthodontists play integrative roles that enable them to achieve the best possible results for their patients. This review will improve the results of interdisciplinary treatments and increase cooperation between dental specialists by drawing attention to the essential connection between orthodontics and periodontics in regular clinical practice.

Mesenchymal Stem Cell-based Scaffolds in Regenerative Medicine of Dental Diseases

Biomedical engineering breakthroughs and increased patient expectations and requests for more comprehensive care are propelling the field of regenerative dentistry forward at a fast pace. Stem cells (SCs), bioactive compounds, and scaffolds are the mainstays of tissue engineering, the backbone of regenerative dentistry. Repairing damaged teeth and gums is a significant scientific problem at present. Novel therapeutic approaches for tooth and periodontal healing have been inspired by tissue engineering based on mesenchymal stem cells (MSCs). Furthermore, as a component of the MSC secretome, extracellular vesicles (EVs) have been shown to contribute to periodontal tissue repair and regeneration. The scaffold, made of an artificial extracellular matrix (ECM), acts as a supporting structure for new cell development and tissue formation. To effectively promote cell development, a scaffold must be non-toxic, biodegradable, biologically compatible, low in immunogenicity, and safe. Due to its promising biological characteristics for cell regeneration, dental tissue engineering has recently received much attention for its use of natural or synthetic polymer scaffolds with excellent mechanical properties, such as small pore size and a high surface-to-volume ratio, as a matrix. Moreover, as a bioactive material for carrying MSC-EVs, the combined application of scaffolds and MSC-EVs has a better regenerative effect on dental diseases. In this paper, we discuss how MSCs and MSC-derived EV treatment may be used to regenerate damaged teeth, and we highlight the role of various scaffolds in this process.

Periodontal ligament stem cell-derived exosome-loaded Emodin mediated antimicrobial photodynamic therapy against cariogenic bacteria

BACKGROUND

This study was conducted to investigate the efficiency of periodontal ligament (PDL) stem cell-derived exosome-loaded Emodin (Emo@PDL-Exo) in antimicrobial photodynamic therapy (aPDT) on Streptococcus mutans and Lactobacillus acidophilus as the cariogenic bacteria.

MATERIALS AND METHODS

After isolating and characterizing PDL-Exo, the study proceeded to prepare and verify the presence of Emo@PDL-Exo. The antimicrobial effect, anti-biofilm activity, and anti-metabolic potency of Emo, PDL-Exo, and Emo@PDL-Exo were then evaluated with and without irradiation of blue laser at a wavelength of 405 ± 10 nm with an output intensity of 150 mW/cm2 for a duration of 60 s. In addition, the study assessed the binding affinity of Emodin with GtfB and SlpA proteins using in silico molecular docking. Eventually, the study examined the generation of endogenous reactive oxygen species (ROS) and changes in the gene expression levels of gelE and sprE.

RESULTS

The study found that using Emo@PDL-Exo-mediated aPDT resulted in a significant decrease in L. acidophilus and S. mutans by 4.90 ± 0.36 and 5.07 log10 CFU/mL, respectively (P < 0.05). The study found that using Emo@PDL-Exo for aPDT significantly reduced L. acidophilus and S. mutans biofilms by 44.7% and 50.4%, respectively, compared to untreated biofilms in the control group (P < 0.05). Additionally, the metabolic activity of L. acidophilus and S. mutans decreased by 58.3% and 71.2%, respectively (P < 0.05). The molecular docking analysis showed strong binding affinities of Emodin with SlpA and GtfB proteins, with docking scores of -7.4 and -8.2 kcal/mol, respectively. The study also found that the aPDT using Emo@PDL-Exo group resulted in the most significant reduction in gene expression of slpA and gtfB, with a decrease of 4.2- and 5.6-folds, respectively, compared to the control group (P < 0.05), likely due to the increased generation of endogenous ROS.

DISCUSSION

The study showed that aPDT using Emo@PDL-Exo can effectively reduce the cell viability, biofilm activity, and metabolic potency of S. mutans and L. acidophilus. aPDT also significantly reduced the expression levels of gtfB and slpA mRNA due to the increased endogenous ROS generation. The findings suggest that Emo@PDL-Exo-mediated aPDT could be a promising antimicrobial approach against cariogenic microorganisms.

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.

Evaluation of anti-biofilm effect of antimicrobial sonodynamic therapy-based periodontal ligament stem cell-derived exosome-loaded kojic acid on Enterococcus faecalis biofilm

Introduction. Antimicrobial sonodynamic therapy (aSDT) is an approach that uses ultrasound waves (UWs) and a sonosensitizer to generate reactive oxygen species (ROS) to damage microbial cells in biofilms. Using nano-carriers, such as exosomes (Exos), to deliver the sonosensitizer can potentially enhance the effectiveness of aSDT.Hypothesis/Gap Statement. aSDT can downregulate the expression of gelE and sprE genes, increasing the production of endogenous ROS and degradation of pre-formed Enterococcus faecalis biofilms.Aim. This study investigated the anti-biofilm effect of aSDT-based periodontal ligament stem cell-derived exosome-loaded kojic acid (KA@PDL-Exo) on pre-formed E. faecalis biofilms in root canals.Methodology. Following the isolation and characterization of PDL-Exo, KA@PDL-Exo was prepared and confirmed. The minimal biofilm inhibitory concentration (MBIC) of KA, PDL-Exo, KA@PDL-Exo and sodium hypochlorite (NaOCl) was determined, and their anti-biofilm effects were assessed with and without UWs. The binding affinity of KA with GelE and SprE proteins was evaluated using in silico molecular docking. Additionally, the study measured the generation of endogenous ROS and evaluated changes in the gene expression levels of gelE and sprE.Results. The results revealed a dose-dependent decrease in the viability of E. faecalis cells within biofilms. KA@PDL-Exo was the most effective, with an MBIC of 62.5 µg ml-1, while NaOCl, KA and PDL-Exo had MBIC values of 125, 250 and 500 µg ml-1, respectively. The use of KA@PDL-Exo-mediated aSDT resulted in a significant reduction of the E. faecalis biofilm (3.22±0.36 log10 c.f.u. ml-1; P<0.05). The molecular docking analysis revealed docking scores of -5.3 and -5.2 kcal mol-1 for GelE-KA an SprE-KA, respectively. The findings observed the most significant reduction in gene expression of gelE and sprE in the KA@PDL-Exo group, with a decrease of 7.9- and 9.3-fold, respectively, compared to the control group (P<0.05).Conclusion. The KA@PDL-Exo-mediated aSDT was able to significantly reduce the E. faecalis load in pre-formed biofilms, decrease the expression of gelE and srpE mRNA, and increase the generation of endogenous ROS. These findings imply that KA@PDL-Exo-mediated aSDT could be a promising anti-biofilm strategy that requires additional in vitro and in vivo investigations.

Mesenchymal stem cell-derived extracellular vesicles for treatment of bone loss within periodontitis in pre-clinical animal models: a meta-analysis

BACKGROUND

Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) represent an effective and promising strategy for periodontitis, although studies remain pre-clinical. Herein, a meta-analysis was conducted to assess the efficacy of MSC-EVs in animal models of periodontitis.

METHODS

The PubMed, Web of Science, and Embase electronic databases were searched up to Dec 2022 to retrieve preclinical studies examining the use of MSC-EVs for periodontitis treatment. Meta-analyses and sub-group analyses were performed to assess the effect of MSC-EVs on Bone Volume/Total Volume (BV/TV) or the distance between the cementoenamel junction and alveolar bone crest (CEJ-ABC) in pre-clinical animal models of periodontitis.

RESULTS

11 studies published from Mar 2019 to Oct 2022 met the inclusion criteria. Overall, MSC-EVs contributed to periodontal bone regeneration in the inflammatory bone loss area due to periodontitis, as represented by a weighted mean difference (WMD) of 14.07% (95% CI = 6.73, 21.41%, p < 0.001) for BV/TV and a WMD of -0.12 mm (95% CI= -0.14, -0.11 mm, p < 0.001) for CEJ-ABC. However, sub-analysis suggested that there was no significant difference in CEJ-ABC between studies with bioactive scaffolds and studies without bioactive scaffolds (p = 0.60).

CONCLUSIONS

The present study suggests that MSC-EVs may represent an attractive therapy for the treatment of inflammatory bone loss within periodontitis.

Curcumin-primed periodontal ligament stem cells-derived extracellular vesicles improve osteogenic ability through the Wnt/β-catenin pathway

Introduction: Curcumin has broad application prospects in the prevention and treatment of periodontal diseases. Periodontal ligament stem cell-derived extracellular vesicles (PDLSC-EV) can effectively promote periodontal tissue regeneration and possess good drug delivery capability. Superior pharmacological effects can be exerted using PDLSC-EV as a curcumin carrier. Methods: In the present study, we constructed curcumin-primed PDLSCs-derived extracellular vesicles (Cur-PDLSC-EV) from cell culture supernatants of curcumin-pretreated PDLSCs by ultracentrifugation and investigated their effects on the proliferation, migration, and osteogenic ability of PDLSCs and the corresponding downstream molecular pathways. Results: Both Cur-PDLSC-EV and PDLSC-EV promoted osteoblast proliferation and migration. Compared with PDLSC-EV, Cur-PDLSC-EV possessed a more potent pro-osteogenic ability. Moreover, the improved osteogenesis of Cur-PDLSC-EV was related to the activation of the Wnt/β-catenin signaling pathway. Conclusion: This study suggests that Cur-PDLSC-EV can promote osteogenic differentiation by activating Wnt/β-catenin, providing reference bases for the treatment of periodontal diseases.

Periodontal Ligament Stem Cell Exosomes Key to Regulate Periodontal Regeneration by miR-31-5p in Mice Model

Introduction

Periodontitis is a chronic inflammatory disease that causes alveolar bone loss. Diabetes is one of the most important factors contributing to periodontitis. Exosomes derived from mesenchymal stem cells (MSCs-Exo) have been reported to promote bone regeneration. This study aimed to examine the function and mechanism of exosomes derived from periodontal ligament stem cells (PDLSCs-Exo) in regulating periodontal regeneration in diabetic periodontitis.

Methods

Exosomes derived from normal-glucose-cultured PDLSCs (NG-PDLSCs-Exo) and high-glucose-preconditioned PDLSCs (HG-PDLSCs-Exo) were used. Their effects on RAW264.7 cells were investigated by TRAP staining and quantitative real time-polymerase chain reaction (qRT-PCR). The role of exosomal miR-31-5p in osteoclast differentiation was tested using qRT-PCR, double luciferase analysis, and Western blotting. We investigated the effects of these two types of PDLSCs-Exo on alveolar bone loss in vivo in mice with experimental periodontitis.

Results

PDLSCs-Exo were transferred to RAW264.7, and HG-PDLSCs-Exo inhibited osteoclast formation to a lesser extent than NG-PDLSCs-Exo. Further studies revealed the effect of PDLSCs-Exo on osteoclastogenesis via the miR-31-5p/eNOS signaling pathway. In mice with experimental periodontitis, PDLSCs-Exo reduced alveolar bone destruction and decreased the number of osteoclasts on the alveolar bone surface.

Conclusion

Our results suggest that exosomal miR-31-5p derived from PDLSCs regulates alveolar bone regeneration by targeting eNOS.

Advances in hydrogels for the treatment of periodontitis

Periodontitis is the second most prevalent oral disease and can cause serious harm to human health. Hydrogels are excellent biomaterials that can be used for periodontitis as drug delivery platforms to achieve inflammation control through high drug delivery efficiency and sustained drug release and as tissue scaffolds to achieve tissue remodelling through encapsulated cell wrapping and effective mass transfer. In this review, we summarize the latest advances in the treatment of periodontitis with hydrogels. The pathogenic mechanisms of periodontitis are introduced first, followed by the recent progress of hydrogels in controlling inflammation and tissue reconstruction, in which the specific performance of hydrogels is discussed in detail. Finally, the challenges and limitations of hydrogels for clinical applications in periodontitis are discussed and possible directions for development are proposed. This review aims to provide a reference for the design and fabrication of hydrogels for the treatment of periodontitis.

Effects of Photobiomodulation Using Low-Level Laser Therapy on Alveolar Bone Repair

Alveolar bone repair is a complex and extremely important process, so that functions such as the mastication, occlusion and osseointegration of implants can be properly reestablished. Therefore, in order to optimize this process, many procedures have been used, such as grafting with biomaterials and the application of platelet-rich fibrin (PRF). Another method that has been studied is the use of photobiomodulation (PBM) with the use of low-level laser therapy (LLLT), which, through the absorption of photons by the tissue, triggers photochemical mechanisms in the cells so that they start to act in the search for homeostasis of the affected region. Therefore, the objective of this review was to analyze the use of LLLT as a possible auxiliary tool in the alveolar bone repair process. A search was carried out in scientific databases (PubMed/MEDLINE, Web of Science, Scopus and Cochrane) regarding the following descriptors: “low-level laser therapy AND alveolar bone repair” and “photobiomodulation AND alveolar bone repair”. Eighteen studies were selected for detailed analysis, after excluding duplicates and articles that did not meet predetermined inclusion or non-inclusion criteria. According to the studies, it has been seen that LLLT promotes the acceleration of alveolar repair due to the stimulation of ATP production, activation of transcription and growth factors, attenuation of the inflammatory process and induction of angiogenesis. These factors depend on the laser application protocol, and the Gallium Aluminum Arsenide—GaAlAs laser, with a wavelength of 830 nm, was the most used and, when applications of different energy densities were compared, the highest dosages showed themselves to be more efficient. Thus, it was possible to conclude that PBM with LLLT has beneficial effects on the alveolar bone repair process due to its ability to reduce pain, the inflammatory process, induce vascular sprouting and, consequently, accelerate the formation of a new bone matrix, favoring the maintenance or increase in height and/or thickness of the alveolar bone ridge.

Enhanced Proliferative and Osteogenic Potential of Periodontal Ligament Stromal Cells

Cell-based therapies using periodontal ligament stromal cells (PDLSC) for periodontal regeneration may represent an alternative source for mesenchymal stromal cells (MSC) to MSC derived from bone marrow (MSC(M)) and adipose tissue (MSC(AT)). We aimed to characterize the osteogenic/periodontal potential of PDLSC in comparison to MSC(M) and MSC(AT). PDLSC were obtained from surgically extracted healthy human third molars, while MSC(M) and MSC(AT) were obtained from a previously established cell bank. Flow cytometry, immunocytochemistry, and cell proliferation analyses provided cellular characteristics from each group. Cells from the three groups presented MSC-like morphology, MSC-related marker expression, and multilineage differentiation capacity (adipogenic, chondrogenic, and osteogenic). In this study, PDLSC expressed osteopontin, osteocalcin, and asporin, while MSC(M) and MSC(AT) did not. Of note, only PDLSC expressed CD146, a marker previously applied to identify PDLSC, and presented higher proliferative potential compared to MSC(M) and MSC(AT). Upon osteogenic induction, PDLSC exhibited higher calcium content and enhanced upregulation of osteogenic/periodontal genes compared to MSC(M) and MSC(AT), such as Runx2, Col1A1 and CEMP-1. However, the alkaline phosphatase activity of PDLSC did not increase. Our findings suggest that PDLSC might be a promising cell source for periodontal regeneration, presenting enhanced proliferative and osteogenic potential compared to MSC(M) and MSC(AT).

Exosome-loaded scaffolds for regenerative medicine in hard tissues

Tissue engineering can be used to repair tissue by employing bioscaffolds that provide better spatial control, porosity, and a three-dimensional (3D) environment like the human body. Optimization of injectability, biocompatibility, bioactivity, and controlled drug release are also features of such scaffolds. The 3D shape of the scaffold can control cell interaction and improve cell migration, proliferation, and differentiation. Exosomes (EXOs) are nanovesicles that can regulate osteoblast activity and proliferation using a complex composition of lipids, proteins, and nucleic acids in their vesicles. Due to their excellent biocompatibility and efficient cellular internalization, EXOs have enormous potential as desirable drug/gene delivery vectors in the field of regenerative medicine. They can cross the biological barrier with minimal immunogenicity and side effects. Scaffolds that contain EXOs have been studied extensively in both basic and preclinical settings for the regeneration and repair of both hard (bone, cartilage) and soft (skin, heart, liver, kidney) tissue. Cell motility, proliferation, phenotype, and maturation can all be controlled by EXOs. The angiogenic and anti-inflammatory properties of EXOs significantly influence tissue healing. The current study focused on the use of EXO-loaded scaffolds in hard tissue regeneration.