Nicotinamide Riboside Modulates HIF-1 Signaling to Maintain and Enhance Odontoblastic Differentiation in Human Dental Pulp Stem Cells.

Human dental pulp stem cells (hDPSCs) play a vital role in the regeneration of the pulp-dentin complex after pulp disease. While the regeneration efficiency relies on the odontoblastic differentiation capacity of hDPSCs, this is difficult to regulate within the pulp cavity. Although nicotinamide riboside (NR) has been found to promote tissue regeneration, its specific role in pulp-dentin complex regeneration is not fully understood. Here, we aimed to explore the role of NR in the odontoblastic differentiation of hDPSCs and its underlying molecular mechanism. It was found that NR enhanced the viability and retarded senescence in hDPSCs with higher NAD+/NADH levels. In contrast to the sustained action of NR, the multi-directional differentiation of hDPSCs was enhanced after NR pre-treatment. Moreover, in an ectopic pulp regeneration assay in nude mice, transplantation of hDPSCs pretreated with NR promoted the formation of a dentin-like structure surrounded by cells positively expressing DMP-1 and DSPP. RNA-Seq demonstrated inhibition of the HIF-1 signaling pathway in hDPSCs pretreated with NR. The number of HIF-1α-positive cells was significantly decreased in hDPSCs pretreated by NR in vivo. Similarly, NR significantly downregulated the expression of HIF-1α in vitro. The findings suggested that NR could potentially regulate hDPSC odontoblastic differentiation and promote the development of innovative strategies for dental pulp repair.

Semi-flipped classroom-based learning interventions in a traditional curriculum of oral medicine: students' perceptions and teaching achievements.

BACKGROUND: In recent years, flipped classes have emerged and become popular in college medical education. However, due to the huge medical learning system and the limited pre-class study time of students, it is difficult to implement in all courses. And then we adopted the semi-flipped classes (SFCs) to evaluate its teaching effect. This study analysed three educational methods that can be used in oral medicine courses: online education, offline education, and semi-flipped classes. METHODS: We used two surveys to evaluate the three educational methods. In the first survey 46 teachers and 238 undergraduates shared their experience of the live-streaming and traditional offline courses offered in the different oral medicine curricula; we used anonymous questionnaires to evaluate their class experience. In the second survey 94 students shared their experience of the semi-flipped and traditional classrooms. Students who attended the SFCs in the experimental group learned about the oral mucosa disease by themselves using an online video course and then participated in offline interaction with teachers. The evaluation of the above educational methods was conducted using the anonymous questionnaires and final exam assessment. RESULTS: According to the first survey, teachers and students both agreed that the overall teaching experience and learning effectiveness in offline education are superior to those in online education. According to the second survey, students who participated in the SFCs performed better in the final exam than those who participated in the simple offline classes. Additionally, the survey showed that the new teaching method helped students gain more knowledge and positively influenced their clinical practice. CONCLUSIONS: Compared with the online and offline educational methods, the SFC showed better results in both the questionnaire and final exam assessment. Hence, the effectiveness of medical education can be improved by adopting a teaching mode that combines online and offline teaching methods. Scientific and logical SFCs designs, along with their effective implementation, would eventually make SFCs an important tool for medical education.

Application of virtual reality and haptics system Simodont in Chinese dental education: A scoping review.

INTRODUCTION: Virtual reality (VR) and haptic simulation technology have been increasingly implemented in dental training. Since the first haptic VR dental simulator (Simodont) was introduced 10 years ago, it has been applied in more than 40 universities in mainland China. This scoping review aimed to review literature, showcasing the teaching reform of dental virtual simulation in mainland China to global dental education peers. METHODS: This scoping review was conducted using the PRISMA extension for scoping review guidelines. Seven electronic databases were searched, and two reviewers independently performed the selection and characterization of the studies. RESULTS: The final scoping review included 12 studies. Four studies focused on the G. V. Black class II cavity, three on manual dexterity skills training, two on full metal crown preparation, one on pulpal access and coronal cavity preparation, one on flipped classroom teaching, and one on 'doctor-patient communication' skills. DISCUSSION: The most critical scenarios, self-assessment, working posture, curriculum setting, training and cost are analysed and discussed. CONCLUSION: Haptic simulation technology is a valuable complementary tool to the phantom head in dental education. The combined utilization of these two training devices has been superior to either in isolation. However, there is a lack of research on the sequencing of the two systems, as well as the appropriate distribution of curriculum between them. It is necessary for educators to organize or engage in experience sharing, collaboration and knowledge dissemination. These actions are essential for promoting effective teaching within dental educational institutions.

Long noncoding RNA MEG3 expressed in human dental pulp regulates LPS-Induced inflammation and odontogenic differentiation in pulpitis.

Pulpitis refers to inflammation of the inner pulp by invading microbes, and tissue repair occurs due to odontogenic differentiation of human dental pulp cells (hDPCs) with multidifferentiation potential. Long noncoding RNAs (lncRNAs) can modulate numerous pathological and biological processes; however, the role of lncRNAs in the inflammation and regeneration of the dentin-pulp complex in pulpitis is unclear. Here, we performed high-throughput sequencing to identify differentially expressed lncRNAs between human normal and inflamed pulp and concluded that lncMEG3 (lncRNA maternally expressed gene 3, MEG3) was significantly upregulated in both inflamed pulp and LPS-treated hDPCs. MEG3 expression in the pulp tissue was detected using the RNAscope® technique. RNA pulldown assays identified the MEG3-interacting proteins and the potential mechanisms. With MEG3 knockdown, we investigated the role of MEG3 in the secretion of inflammatory cytokines in LPS-treated hDPCs and odontogenic differentiation of hDPCs. MEG3 downregulation inhibited the secretion of TNF-α, IL-1ß and IL-6 in LPS-treated hDPCs, and the p38/MAPK signaling pathway may be related to this effect. MEG3 knockdown promoted odontogenic differentiation of hDPCs by regulating the Wnt/ß-catenin signaling pathway. Our study suggested that MEG3 has a negative effect on inflammation and regeneration of the dentin-pulp complex in pulpitis.

The picture of undergraduate dental basic research education: a scoping review.

BACKGROUND: Undergraduate dental basic research education (UDBRE) is broadly regarded as an important approach for cultivating scientific research talent. This scoping review aims to summarize the current status of UDBRE in terms of educational goals, teaching program and content, assessment system, training outcomes, barriers, and reflections. METHODS: The authors performed a systematic literature search in PubMed, Web of Science, and Education Resources Information Center (ERIC) to identify peer-reviewed articles written in English from their inception to January 29, 2021. Articles were reviewed and screened according to the inclusion and exclusion criteria. Related data from the included publications were then collected and summarized. RESULTS: The authors searched 646 publications and selected 16 articles to include in the study. The education goals included cultivating five major dental basic research capabilities (n=10, 62.5%) and developing interest in basic research (n=2, 12.5%). As for the teaching program, the mentor-guided student research project was the most popular (n=11, 68.8%), followed by didactic courses (n=5, 31.3%), experimental skills training (n=1, 6.3%), and the combination of the above forms (n=3, 18.8%). However, the assessment system and training outcome diverged. Existing evidence showed that UDBRE reached satisfying education outcomes. Barriers included excessive curriculum burden (n=2, 12.5%), tutor shortage (n=3, 18.8%), lack of financial support (n=5, 31.3%), and inadequate research skills and knowledge (n=5, 31.3%). CONCLUSIONS: Although efforts were made, the variation between studies revealed the immature status of UDBRE. A practical UDBRE education system paradigm was put forward. Meanwhile, more research is required to optimize a robust UDBRE system with clear education goals, well-designed teaching forms, and convincing assessment systems.

LncRNA DANCR sponges miR-216a to inhibit odontoblast differentiation through upregulating c-Cbl.

Enhanced odontoblast differentiation of human dental pulp cells (hDPCs) is considered a keystone in dentin-pulp complex formation. We have revealed lncRNA DANCR was implicated in this differentiation program, however, its mechanism in odontoblast differentiation of hDPCs remains further explored. In this study, by employing loss-of-function approach, we identified downregulation of DANCR drived odontoblast differentiaion of hDPCs. Bioinformatics analysis was utilized to show that DANCR contained binding site for miR-216a and an inverse correlation between DANCR and miR-216a was obtained. Dual luciferase reporter assay and RNA-binding protein immunoprecipitation (RIP) were applied to further confirm that DANCR conferred its functions by directly binding to miR-216a. Notably, miR-216a was able to bind to the 3'-UTR of c-Cbl and repressed its expression. In addition, the protein level of c-CBL was significantly downregulated during hDPCs differentiation, while c-Cbl overexpression inhibited odontoblast differentiation of hDPCs. Moreover, downregulation of miR-216a efficiently reversed the suppression of c-Cbl level and odontoblast differentiation induced by knockdown of DANCR. Taken together, these analyses indicated that DANCR positively regulated the expression of c-Cbl, through sponging miR-216a, and inhibited odontoblast differentiation of hDPCs. Our results will extend the field of clinical application for cell-based therapy in regenerative medicine.

The national dental undergraduate clinical skills competition known as the Guanghua Cup: an innovative and effective program that promoted undergraduate dental education in China.

BACKGROUND: The National Dental Undergraduate Clinical Skills Competition known as the Guanghua Cup was held in Guangzhou, China, for three consecutive years from 2017 to 2019 to promote the clinical teaching of undergraduate dental education and to enhance communication among different universities. The present study aimed to introduce the organization, procedures, and consequences of the competition, in addition to analyzing the influences of competition on the reform of undergraduate dental education. METHODS: By analyzing the descriptive statistics of the Guanghua Cup, the competitions' organization, the participating students' performances, and the outcomes of competitions were analyzed. After distributing questionnaires to all participants of the 2nd and 3rd Cups, their attitudes towards the competition and their evaluation of the role of the competitions in promoting undergraduate dental education were analyzed. RESULTS: A total of 24 schools participated in the 3 competition years. The contents of the competitions covered cariology, endodontics, periodontology, prosthodontics, oral and maxillofacial surgery, dental anatomy, and first aid (e.g., operative skills and theoretical knowledge). Compared with those of the 2nd Cup, the mean scores of the operative skills significantly improved in the stations related to periodontology, prosthodontics, and dental anatomy (p < 0.05) in the 3rd Cup. In addition, 338 valid questionnaires were collected, for a response rate of 87.79 %. Overall, the participants spoke highly of the Guanghua Cup. Based on their self-perception and self-evaluation, the majority of interviewees agreed that the competition helped develop collegiality and teamwork among the participating students, improved the students' clinical skills and promoted the improvement of teaching resources (e.g., purchasing and updating equipment, models or experimental materials). CONCLUSIONS: The competition enjoyed the widest coverage since it involved dental schools from all of the different geographical regions of China. Dental students could exhibit their clinical skills in a competitive environment and develop collegiality and teamwork. Future competitions should be optimized through their organization and contents. The education quality of the participating schools affected by such competition should be investigated in a more objective and comparable way.

Functional Dental Pulp Regeneration: Basic Research and Clinical Translation.

Pulpal and periapical diseases account for a large proportion of dental visits, the current treatments for which are root canal therapy (RCT) and pulp revascularisation. Despite the clinical signs of full recovery and histological reconstruction, true regeneration of pulp tissues is still far from being achieved. The goal of regenerative endodontics is to promote normal pulp function recovery in inflamed or necrotic teeth that would result in true regeneration of the pulpodentinal complex. Recently, rapid progress has been made related to tissue engineering-mediated pulp regeneration, which combines stem cells, biomaterials, and growth factors. Since the successful isolation and characterisation of dental pulp stem cells (DPSCs) and other applicable dental mesenchymal stem cells, basic research and preclinical exploration of stem cell-mediated functional pulp regeneration via cell transplantation and cell homing have received considerably more attention. Some of this effort has translated into clinical therapeutic applications, bringing a ground-breaking revolution and a new perspective to the endodontic field. In this article, we retrospectively examined the current treatment status and clinical goals of pulpal and periapical diseases and scrutinized biological studies of functional pulp regeneration with a focus on DPSCs, biomaterials, and growth factors. Then, we reviewed preclinical experiments based on various animal models and research strategies. Finally, we summarised the current challenges encountered in preclinical or clinical regenerative applications and suggested promising solutions to address these challenges to guide tissue engineering-mediated clinical translation in the future.

The evaluation of stomatology English education in China based on 'Guanghua cup' international clinical skill exhibition activity.

BACKGROUND: English education in professional areas has become more and more important with the increasing internationalization of health profession education in countries around the world. In this study, we aimed to evaluate current Chinese stomatology English education based on Chinese participants' ability to apply stomatology English during an international stomatology skill competition called the 'Guanghua Cup activity'. METHODS: The registration rate of English and Chinese volunteers and the answer rate and accuracy of Chinese and international contestants on the English knowledge quiz were statistically described. A five-point Likert scale questionnaire was delivered to all participants. The data were analyzed using the Spearman test, Kruskal-Wallis rank sum test and Mann-Whitney U test. RESULTS: Among the 194 students, the English and Chinese volunteer registration rate was 7.73 and 30.93%, respectively. The answer rate of Chinese contestants and international contestants in the English quiz was 25 and 75%, with an accuracy rate of 50 and 66.70%, respectively. The questionnaire was graded by Likert five-level classification. There was a positive correlation between the use of English textbooks in classes and the communication with international teachers and students in the competition (Rs = 0.348, p = 0.016). English volunteers had more preparation in English before the competition, more opportunities to communicate with international peers, and greater improvement in English ability than the contestants and Chinese volunteers (p < 0.001). After the competition, all participants paid more attention to stomatology English (p < 0.001). CONCLUSIONS: Chinese stomatology students have difficulty in stomatology English application. The 'Guanghua Cup' helps to improve English proficiency of English volunteers and arouses the interest of stomatology English for all participants. Chinese stomatology school needs to strengthen and reach a consensus in stomatology English education.

The antibacterial, cytotoxic, and flexural properties of a composite resin containing a quaternary ammonium monomer.

STATEMENT OF PROBLEM: The use of composite resin to restore teeth has increased substantially during the last decades. However, secondary caries and the fracture of restorations are the leading reasons for clinical restoration failure. Mechanically strong composite resins with caries-inhibition capabilities are needed. Although antibacterial dimethacrylate quaternary ammonium monomers have been synthesized, composite resin containing dimethacrylate quaternary ammonium monomers and glass fillers has rarely been reported. PURPOSE: The purpose of this in vitro study was to evaluate the possibility of the clinical use of an experimental composite resin containing urethane dimethacrylate quaternary ammonium compound (UDMQA-12) by investigating its antibacterial activity, cytotoxicity, flexural strength, and flexural modulus. MATERIAL AND METHODS: Antibacterial activity against Streptococcus mutans was investigated by means of direct contact test. The antibacterial activity of specimens after water immersion and saliva treatment was also tested. These were compared with a commercially available composite resin, Z250, and a glass ionomer cement, Fuji VII. Effects of the eluent from the experimental composite resin on the metabolic activity of human dental pulp cells were quantified. Disks of 1 mm in thickness and 15 mm in diameter were used in the antibacterial and cytotoxic tests. Flexural strength and flexural modulus were measured with a 3-point bend test with bars of 2×2×25 mm. Three commercially available composite resins (Filtek Z250, G-aenial Anterior, and G-aenial Posterior) were used as controls in the flexural test. RESULTS: Bacterial growth was inhibited on the experimental composite resin. After water immersion or saliva treatment, the experimental composite resin showed significant antibacterial effect compared with the conventional composite resin (P<.05). No significant difference was found in cytotoxicity between the experimental composite resin and the conventional composite resin (P＞.05), and a significantly higher cytotoxicity was shown by glass ionomer cement compared with the experimental composite resin and the conventional composite resin (P<.05). The conventional composite resin had the highest flexural strength and flexural modulus (P<.05), followed by the experimental composite resin, then G-ænial Posterior and G-ænial Anterior. CONCLUSIONS: The antibacterial experimental composite resin was biocompatible and had mechanical properties similar to those of some commercially available composite resins. It might, therefore, be useful in preventing the occurrence of secondary caries.

TRIM33 is essential for osteoblast proliferation and differentiation via BMP pathway.

Tripartite motif containing 33 (TRIM33) functions both as a positive and negative regulator of the TGF-ß/BMP pathway in tumors; however, its effect and mechanism during osteoblast proliferation and differentiation, which involves the TGF-ß/BMP pathway is not defined. In this study, we used mouse C3H10T1/2 mesenchymal stem cell line and MC3T3-E1 preosteoblasts to investigate the role of TRIM33 during this process. The results demonstrated that the expression of TRIM33 increased during the differentiation. Moreover, the overexpression or knockdown of TRIM33 resulted in both an augmentation or decrease in osteoblast differentiation, which were measured by the expression of alkaline phosphatase (ALP) at the mRNA level, both Runt-related transcription factor 2 (Runx2) and osteocalcin (OCN) at the protein level, and the formation of mineral modules. To further demonstrate the mechanism of TRIM33 in this process, we found that TRIM33 could positively mediate the BMP pathway by forming TRIM33-Smad1/5 complex. This interaction between TRIM33 and Smad1/5 triggered the phosphorylation of Smad1/5. In addition, the essential role of TRIM33 in osteoblast proliferation was determined in this study by CellCounting Kit (CCK) -8 and cell cycle assays. In summary, we establish the function of TRIM33 as a positive regulator of osteoblast differentiation in BMP pathway, which mediates its effect through its interaction with and activation of Smad1/5. In addition, the results clearly demonstrate that TRIM33 is necessary for osteoblast proliferation by regulating cell cycle. These results suggest that TRIM33 can be a positive target of osteoblast proliferation and differentiation through BMP pathway.

lncRNA DANCR suppresses odontoblast-like differentiation of human dental pulp cells by inhibiting wnt/ß-catenin pathway.

Long noncoding RNAs (lncRNAs) have recently emerged as an important class of regulatory molecules in diverse biological processes, although lncRNA involvement in the odontoblast-like differentiation of human dental pulp cells (hDPCs) is poorly understood. We investigate the expression of lncRNAs in this differentiation and explore their underlying role and the involved mechanism. Integrated comparative lncRNA microarray profiling was used to examine lncRNA expression during this differentiation. The differential expression of lncRNAs was validated by quantitative real-time reverse transcription plus the polymerase chain reaction. Differential lncRNA overexpression was performed with an adenoviral vector and the role and mechanism was then investigated in odontoblast-like differentiation. We identified 139 differentially expressed lncRNAs during this differentiation. Among them, five lncRNAs differentially expressed in microarray analysis were validated. Notably, lncRNA DANCR expression was significantly downregulated during hDPC differentiation to odontoblast-like cells in a time-dependent manner. Moreover, lncRNA DANCR overexpression blocked mineralized nodule formation and the expression of DSPP and DMP-1 in hDPCs after 14 days of odontogenic induction. Importantly, the upregulation of DANCR significantly decreased the expression levels of p-GSK-3ß and ß-catenin expression indicating that lncRNA DANCR can inhibit the activation of the Wnt/ß-catenin signal pathway during the odontoblast-like differentiation of hDPCs. Thus, the modulation of Wnt/ß-catenin signaling by lncRNA DANCR represents a potential therapeutic option for reparative dentin formation and regenerative endodontics.

JNK MAPK is involved in BMP-2-induced odontoblastic differentiation of human dental pulp cells.

Bone morphogenetic protein-2 (BMP-2) is a multi-functional growth factor belonging to the transforming growth factor ß superfamily that has a broad range of activities that affect many different cell types. BMP-2 induces odontoblastic differentiation of human dental pulp cells (DPCs), but the underlying mechanism remains unclear. In this study, we investigated the potential role of the JNK mitogen-activated protein kinases (MAPK) pathway in BMP-2-induced odontoblastic differentiation of DPCs. The levels of phosphorylated and unphosphorylated JNK MAPK were quantified by Western blot analysis following treatment with BMP-2 and the JNK inhibitor SP600125. The role of JNK MAPK in the BMP-2-induced odontoblastic differentiation of DPCs was determined by measuring alkaline phosphatase (ALP) activity and by examining the expression of odontoblastic markers using quantitative real-time polymerase chain reaction analysis. The effect of JNK MAPK silencing on odontoblastic differentiation was also investigated. BMP-2 upregulated the phosphorylation of JNK in DPCs in a dose- and time-dependent manner. Early markers of odontoblastic differentiation, including ALP activity, osteopontin and dentin matrix protein-1, were not inhibited by the JNK inhibitor. However, the JNK inhibitor, SP600125, significantly inhibited late-stage differentiation of odontoblasts, including the gene expression of osteocalcin, dentin sialophosphoprotein and bone sialoprotein, and also reduced the formation of mineralized nodules in BMP-2-treated DPCs. Consistent with this observation, silencing of JNK MAPK also decreased late-stage odontoblastic differentiation. Taken together, these findings suggest that JNK activity is required for late-stage odontoblastic differentiation induced by BMP-2.

Diabetic Macrophage Exosomal miR-381-3p Inhibits Epithelial Cell Autophagy Via NR5A2.

PURPOSE: To explore the mechanism underlying autophagy disruption in gingival epithelial cells (GECs) in diabetic individuals. METHODS AND MATERIALS: Bone marrow-derived macrophages (BMDMs) and GECs were extracted from C57/bl and db/db mice, the exosomes (Exo) were isolated from BMDMs. qRT‒PCR and Western blotting were performed to analyse gene expression. The AnimalTFDB database was used to identify relevant transcription factors, and miRNA sequencing was utilised to identify relevant miRNAs with the aid of the TargetScan/miRDB/miRWalk databases. A dual-luciferase assay was conducted to verify intermolecular targeting relationships. RESULTS: Similar to BMDMs, BMDM-derived Exos disrupted autophagy and exerted proinflammatory effects in GEC cocultures, and ATG7 may play a vital role. AnimalTFDB database analysis and dual-luciferase assays indicated that NR5A2 is the most relevant transcription factor that regulates Atg7 expression. SiRNA-NR5A2 transfection blocked autophagy in GECs and exacerbated inflammation, whereas NR5A2 upregulation restored ATG7 expression and ameliorated ExoDM-mediated inflammation. MiRNA sequencing, with TargetScan/miRDB/miRWalk analyses and dual-luciferase assays, confirmed that miR-381-3p is the most relevant miRNA that targets NR5A2. MiR-381-3p mimic transfection blocked autophagy in GECs and exacerbated inflammation, while miR-381-3p inhibitor transfection restored ATG7 expression and attenuated ExoDM-mediated inflammation. CONCLUSION: BMDM-derived Exos, which carry miR-381-3p, inhibit NR5A2 and disrupt autophagy in GECs, increasing periodontal inflammation in diabetes.

Lysosomal dysfunction-derived autophagy impairment of gingival epithelial cells in diabetes-associated periodontitis with altered protein acetylation.

Diabetes-associated periodontitis (DP) presents severe inflammation and resistance to periodontal conventional treatment, presenting a significant challenge in clinical management. In this study, we investigated the underlying mechanism driving the hyperinflammatory response in gingival epithelial cells (GECs) of DP patients. Our findings indicate that lysosomal dysfunction under high glucose conditions leads to the blockage of autophagy flux, exacerbating inflammatory response in GECs. Single-cell RNA sequencing and immunohistochemistry analyses of clinical gingival epithelia revealed dysregulation in the lysosome pathway characterized by reduced levels of lysosome-associated membrane glycoprotein 2 (LAMP2) and V-type proton ATPase 16 kDa proteolipid subunit c (ATP6V0C) in subjects with DP. In vitro stimulation of human gingival epithelial cells (HGECs) with a hyperglycemic microenvironment showed elevated release of proinflammatory cytokines, compromised lysosomal acidity and blocked autophagy. Moreover, HGECs with deficiency in ATP6V0C demonstrated impaired autophagy and heightened inflammatory response, mirroring the effects of high glucose stimulation. Proteomic analysis of acetylation modifications identified altered acetylation levels in 28 autophagy-lysosome pathway-related proteins and 37 sites in HGECs subjected to high glucose stimulation or siATP6V0C. Overall, our finding highlights the pivotal role of lysosome impairment in autophagy obstruction in DP and suggests a potential impact of altered acetylation of relevant proteins on the interplay between lysosome dysfunction and autophagy blockage. These insights may pave the way for the development of effective therapeutic strategies against DP.

Providing biomimetic microenvironment for pulp regeneration via hydrogel-mediated sustained delivery of tissue-specific developmental signals.

Regenerative endodontic therapy is a promising approach to restore the vitality of necrotic teeth, however, pulp regeneration in mature permanent teeth remains a substantial challenge due to insufficient developmental signals. The dentin is embryologically and histologically similar to the pulp, which contains a cocktail of pulp-specific structural proteins and growth factors, thus we proposed an optimizing strategy to obtain dentin matrix extracted proteins (DMEP) and engineered a DMEP functionalized double network hydrogel, whose physicochemical property was tunable by adjusting polymer concentrations to synchronize with regenerated tissues. In vitro models showed that the biomimetic hydrogel with sustained release of DMEP provided a beneficial microenvironment for the encapsulation, propagation and migration of human dental pulp stem cells (hDPSCs). The odontogenic and angiogenic differentiation of hDPSCs were enhanced as well. To elicit the mechanism hidden in the microenvironment to guide cell fate, RNA sequencing was performed and 109 differential expression of genes were identified, the majority of which enriched in cell metabolism, cell differentiation and intercellular communications. The involvement of ERK, p38 and JNK MAPK signaling pathways in the process was confirmed. Of note, in vivo models showed that the injectable and in situ photo-crosslinkable hydrogel was user-friendly for root canal systems and was capable of inducing the regeneration of highly organized and vascularized pulp-like tissues in root segments that subcutaneously implanted into nude mice. Taken together, this study reported a facile and efficient way to fabricate a cell delivery hydrogel with pulp-specific developmental cues, which exhibited promising application and translation potential in future regenerative endodontic fields.

Antimicrobial Peptide- and Dentin Matrix-Functionalized Hydrogel for Vital Pulp Therapy via Synergistic Bacteriostasis, Immunomodulation, and Dentinogenesis.

The preservation of vital pulps is crucial for maintaining the physiological functions of teeth; however, vital pulp therapy (VPT) of pulpitis teeth remains a substantial challenge due to uncontrolled infection, excessive inflammation, and limited regenerative potential. Current pulp capping agents have restricted effects in the infectious and inflammatory microenvironment. To address this, a multifunctional hydrogel (TGH/DM) with antibacterial, immunomodulatory, and mineralization-promoting effects is designed. The antimicrobial peptide (AMP) and demineralized dentin matrix are incorporated into the hydrogel, achieving sustainable delivery of AMP and a cocktail of growth factors. In vitro results show that TGH/DM could kill endodontic microbiota, ameliorate inflammatory responses of human dental pulp stem cells (hDPSCs), and prompt odontogenic differentiation of inflammatory hDPSCs via activation of peroxisome proliferator-activated receptor gamma. In vivo results suggest that TGH/DM is capable of inducing M2 phenotype transformation of macrophages in mice and fostering the regeneration of the dentin-pulp complex in inflamed pulps of beagle dogs. Overall, this study first proposes the synergistic regulation of AMP and tissue-specific extracellular matrix for the treatment of pulpitis, and the advanced hydrogel provides a facile and effective way for VPT.

Multiomics profiling reveals VDR as a central regulator of mesenchymal stem cell senescence with a known association with osteoporosis after high-fat diet exposure.

The consumption of a high-fat diet (HFD) has been linked to osteoporosis and an increased risk of fragility fractures. However, the specific mechanisms of HFD-induced osteoporosis are not fully understood. Our study shows that exposure to an HFD induces premature senescence in bone marrow mesenchymal stem cells (BMSCs), diminishing their proliferation and osteogenic capability, and thereby contributes to osteoporosis. Transcriptomic and chromatin accessibility analyses revealed the decreased chromatin accessibility of vitamin D receptor (VDR)-binding sequences and decreased VDR signaling in BMSCs from HFD-fed mice, suggesting that VDR is a key regulator of BMSC senescence. Notably, the administration of a VDR activator to HFD-fed mice rescued BMSC senescence and significantly improved osteogenesis, bone mass, and other bone parameters. Mechanistically, VDR activation reduced BMSC senescence by decreasing intracellular reactive oxygen species (ROS) levels and preserving mitochondrial function. Our findings not only elucidate the mechanisms by which an HFD induces BMSC senescence and associated osteoporosis but also offer new insights into treating HFD-induced osteoporosis by targeting the VDR-superoxide dismutase 2 (SOD2)-ROS axis.

TRPV1 Regulates Proinflammatory Properties of M1 Macrophages in Periodontitis Via NRF2.

Periodontitis, characterized by progressive alveolar bone destruction, leads to the loss of attachment and stability of the affected teeth. Macrophages, especially the proinflammatory M1 subtype, are key in periodontitis pathogenesis, driving the disease's inflammatory and destructive processes. Despite existing insight into their involvement, comprehensive understanding of the underlying molecular mechanisms remains limited. TRPV1 is a non-selective cation channel protein and is known to regulate cellular function and homeostasis in macrophages. Our research objective was to investigate the impact of TRPV1 on the proinflammatory attributes of M1 macrophages in periodontal tissues, exploring potential mechanistic pathways. A mouse model of periodontitis was established using Porphyromonas gingivalis inoculation and ligature application around the maxillary second molar. Immunohistological analysis showed a significant reduction in macrophage TRPV1 expression in periodontitis-induced mice. Treatment with capsaicin, a TRPV1 agonist, was observed to effectively elevate TRPV1 expression in these macrophages. Furthermore, micro-computed tomography analysis revealed a marked decrease in alveolar bone resorption in the capsaicin -treated group, compared with vehicle and healthy control groups. Our in vitro findings show that capsaicin treatment successfully attenuated LPS-induced TNF-α and IL-6 production in macrophages, mediated through NRF2 activation, consequently reducing intracellular ROS levels. These findings suggest that TRPV1 agonists, through modulating M1 macrophage activity and up-regulating TRPV1, could be a novel therapeutic approach in periodontal disease management.

Understanding the multi-functionality and tissue-specificity of decellularized dental pulp matrix hydrogels for endodontic regeneration.

Dental pulp is the only soft tissue in the tooth which plays a crucial role in maintaining intrinsic multi-functional behaviors of the dentin-pulp complex. Nevertheless, the restoration of fully functional pulps after pulpitis or pulp necrosis, termed endodontic regeneration, remained a major challenge for decades. Therefore, a bioactive and in-situ injectable biomaterial is highly desired for tissue-engineered pulp regeneration. Herein, a decellularized matrix hydrogel derived from porcine dental pulps (pDDPM-G) was prepared and characterized through systematic comparison against the porcine decellularized nerve matrix hydrogel (pDNM-G). The pDDPM-G not only exhibited superior capabilities in facilitating multi-directional differentiation of dental pulp stem cells (DPSCs) during 3D culture, but also promoted regeneration of pulp-like tissues after DPSCs encapsulation and transplantation. Further comparative proteomic and transcriptome analyses revealed the differential compositions and potential mechanisms that endow the pDDPM-G with highly tissue-specific properties. Finally, it was realized that the abundant tenascin C (TNC) in pDDPM served as key factor responsible for the activation of Notch signaling cascades and promoted DPSCs odontoblastic differentiation. Overall, it is believed that pDDPM-G is a sort of multi-functional and tissue-specific hydrogel-based material that holds great promise in endodontic regeneration and clinical translation. STATEMENT OF SIGNIFICANCE: Functional hydrogel-based biomaterials are highly desirable for endodontic regeneration treatments. Decellularized extracellular matrix (dECM) preserves most extracellular matrix components of its native tissue, exhibiting unique advantages in promoting tissue regeneration and functional restoration. In this study, we prepared a porcine dental pulp-derived dECM hydrogel (pDDPM-G), which exhibited superior performance in promoting odontogenesis, angiogenesis, and neurogenesis of the regenerating pulp-like tissue, further showed its tissue-specificity compared to the peripheral nerve-derived dECM hydrogel. In-depth proteomic and transcriptomic analyses revealed that the activation of tenascin C-Notch axis played an important role in facilitating odontogenic regeneration. This biomaterial-based study validated the great potential of the dental pulp-specific pDDPM-G for clinical applications, and provides a springboard for research strategies in ECM-related regenerative medicine.