Circadian clock genes REV-ERBα regulates the secretion of IL-1ß in deciduous tooth pulp stem cells by regulating autophagy in the process of physiological root resorption of deciduous teeth.

Physiological root resorption is a common occurrence during the development of deciduous teeth in children. Previous research has shown that the regulation of the inflammatory microenvironment through autophagy in DDPSCs is a significant factor in this process. However, it remains unclear why there are variations in the autophagic status of DDPSCs at different stages of physiological root resorption. To address this gap in knowledge, this study examines the relationship between the circadian clock of DDPSCs, the autophagic status, and the periodicity of masticatory behavior. Samples were collected from deciduous teeth at various stages of physiological root resorption, and DDPSCs were isolated and cultured for analysis. The results indicate that the circadian rhythm of important autophagy genes, such as Beclin-1 and LC3, and the clock gene REV-ERBα in DDPSCs, disappears under mechanical stress. Additionally, the study found that REV-ERBα can regulate Beclin-1 and LC3. Evidence suggests that mechanical stress is a trigger for the regulation of autophagy via REV-ERBα. Overall, this study highlights the importance of mechanical stress in regulating autophagy of DDPSCs via REV-ERBα, which affects the formation of the inflammatory microenvironment and plays a critical role in physiological root resorption in deciduous teeth.

Machine learning aided single cell image analysis improves understanding of morphometric heterogeneity of human mesenchymal stem cells.

The multipotent stem cells of our body have been largely harnessed in biotherapeutics. However, as they are derived from multiple anatomical sources, from different tissues, human mesenchymal stem cells (hMSCs) are a heterogeneous population showing ambiguity in their in vitro behavior. Intra-clonal population heterogeneity has also been identified and pre-clinical mechanistic studies suggest that these cumulatively depreciate the therapeutic effects of hMSC transplantation. Although various biomarkers identify these specific stem cell populations, recent artificial intelligence-based methods have capitalized on the cellular morphologies of hMSCs, opening a new approach to understand their attributes. A robust and rapid platform is required to accommodate and eliminate the heterogeneity observed in the cell population, to standardize the quality of hMSC therapeutics globally. Here, we report our primary findings of morphological heterogeneity observed within and across two sources of hMSCs namely, stem cells from human exfoliated deciduous teeth (SHEDs) and human Wharton jelly mesenchymal stem cells (hWJ MSCs), using real-time single-cell images generated on immunophenotyping by imaging flow cytometry (IFC). We used the ImageJ software for identification and comparison between the two types of hMSCs using statistically significant morphometric descriptors that are biologically relevant. To expand on these insights, we have further applied deep learning methods and successfully report the development of a Convolutional Neural Network-based image classifier. In our research, we introduced a machine learning methodology to streamline the entire procedure, utilizing convolutional neural networks and transfer learning for binary classification, achieving an accuracy rate of 97.54%. We have also critically discussed the challenges, comparisons between solutions and future directions of machine learning in hMSC classification in biotherapeutics.

Human cytomegalovirus infection impairs neural differentiation via repressing sterol regulatory element binding protein 2-mediated cholesterol biosynthesis.

Congenital human cytomegalovirus (HCMV) infection is a major cause of abnormalities and disorders in the central nervous system (CNS) and/or the peripheral nervous system (PNS). However, the complete pathogenesis of neural differentiation disorders caused by HCMV infection remains to be fully elucidated. Stem cells from human exfoliated deciduous teeth (SHEDs) are mesenchymal stem cells (MSCs) with a high proliferation and neurogenic differentiation capacity. Since SHEDs originate from the neural crest of the early embryonic ectoderm, SHEDs were hypothesized to serve as a promising cell line for investigating the pathogenesis of neural differentiation disorders in the PNS caused by congenital HCMV infection. In this work, SHEDs were demonstrated to be fully permissive to HCMV infection and the virus was able to complete its life cycle in SHEDs. Under neurogenic inductive conditions, HCMV infection of SHEDs caused an abnormal neural morphology. The expression of stem/neural cell markers was also disturbed by HCMV infection. The impairment of neural differentiation was mainly due to a reduction of intracellular cholesterol levels caused by HCMV infection. Sterol regulatory element binding protein-2 (SREBP2) is a critical transcription regulator that guides cholesterol synthesis. HCMV infection was shown to hinder the migration of SREBP2 into nucleus and resulted in perinuclear aggregations of SREBP2 during neural differentiation. Our findings provide new insights into the prevention and treatment of nervous system diseases caused by congenital HCMV infection.

The temporal protein signature analyses of developing human deciduous molar tooth germ.

The tooth serves as an exemplary model for developmental studies, encompassing epithelial-mesenchymal transition and cell differentiation. The essential factors and pathways identified in tooth development will help understand the natural development process and the malformations of mineralized tissues such as skeleton. The time-dependent proteomic changes were investigated through the proteomics of healthy human molars during embryonic stages, ranging from the cap-to-early bell stage. A comprehensive analysis revealed 713 differentially expressed proteins (DEPs) exhibiting five distinct temporal expression patterns. Through the application of weighted gene co-expression network analysis (WGCNA), 24 potential driver proteins of tooth development were screened, including CHID1, RAP1GDS1, HAPLN3, AKAP12, WLS, GSS, DDAH1, CLSTN1, AFM, RBP1, AGO1, SET, HMGB2, HMGB1, ANP32A, SPON1, FREM1, C8B, PRPS2, FCHO2, PPP1R12A, GPALPP1, U2AF2, and RCC2. Then, the proteomics and transcriptomics expression patterns of these proteins were further compared, complemented by single-cell RNA-sequencing (scRNA-seq). In summary, this study not only offers a wealth of information regarding the molecular intricacies of human embryonic epithelial and mesenchymal cell differentiation but also serves as an invaluable resource for future mechanistic inquiries into tooth development.

Sex-biased sampling may influence Homo naledi tooth size variation.

A frequent source of debate in paleoanthropology concerns the taxonomic unity of fossil assemblages, with many hominin samples exhibiting elevated levels of variation that can be interpreted as indicating the presence of multiple species. By contrast, the large assemblage of hominin fossils from the Rising Star cave system, assigned to Homo naledi, exhibits a remarkably low degree of variation for most skeletal elements. Many factors can contribute to low sample variation, including genetic drift, strong natural selection, biased sex ratios, and sampling of closely related individuals. In this study, we tested for potential sex-biased sampling in the Rising Star dental sample. We compared coefficients of variation for the H. naledi teeth to those for eight extant hominoid samples. We used a resampling procedure that generated samples from the extant taxa that matched the sample size of the fossil sample for each possible Rising Star dental sex ratio. We found that variation at four H. naledi tooth positions-I2, M1, P4, M1-is so low that the possibility that one sex is represented by few or no individuals in the sample cannot be excluded. Additional evidence is needed to corroborate this inference, such as ancient DNA or enamel proteome data, and our study design does not address other potential factors that would account for low sample variation. Nevertheless, our results highlight the importance of considering the taphonomic history of a hominin assemblage and suggest that sex-biased sampling is a plausible explanation for the low level of phenotypic variation found in some aspects of the current H. naledi assemblage.

Bayesian modeling of spatially differentiated multivariate enamel defects of the children's primary maxillary central incisor teeth.

BACKGROUND: The analysis of dental caries has been a major focus of recent work on modeling dental defect data. While a dental caries focus is of major importance in dental research, the examination of developmental defects which could also contribute at an early stage of dental caries formation, is also of potential interest. This paper proposes a set of methods which address the appearance of different combinations of defects across different tooth regions. In our modeling we assess the linkages between tooth region development and both the type of defect and associations with etiological predictors of the defects which could be influential at different times during the tooth crown development. METHODS: We develop different hierarchical model formulations under the Bayesian paradigm to assess exposures during primary central incisor (PMCI) tooth development and PMCI defects. We evaluate the Bayesian hierarchical models under various simulation scenarios to compare their performance with both simulated dental defect data and real data from a motivating application. RESULTS: The proposed model provides inference on identifying a subset of etiological predictors of an individual defect accounting for the correlation between tooth regions and on identifying a subset of etiological predictors for the joint effect of defects. Furthermore, the model provides inference on the correlation between the regions of the teeth as well as between the joint effect of the developmental enamel defects and dental caries. Simulation results show that the proposed model consistently yields steady inferences in identifying etiological biomarkers associated with the outcome of localized developmental enamel defects and dental caries under varying simulation scenarios as deemed by small mean square error (MSE) when comparing the simulation results to real application results. CONCLUSION: We evaluate the proposed model under varying simulation scenarios to develop a model for multivariate dental defects and dental caries assuming a flexible covariance structure that can handle regional and joint effects. The proposed model shed new light on methods for capturing inclusive predictors in different multivariate joint models under the same covariance structure and provides a natural extension to a nested hierarchical model.

Exosomes miR-92a-3p from human exfoliated deciduous teeth inhibits periodontitis progression via the KLF4/PI3K/AKT pathway.

BACKGROUND: Periodontitis is a chronic inflammatory disease mediated by dysbiosis of the oral microflora, resulting in the destruction of periodontal tissue. Increasing evidence suggested that mesenchymal stem cell (MSCs) and exosomes derived from MSCs play a critical role in periodontal tissue regeneration. However, whether stem cells from exfoliated deciduous teeth (SHED)-secreted exosomes can improve the therapeutic potential of periodontitis is largely unknown. OBJECTIVE: Here, we aim to evaluate the effect of SHED-exosomes on inflammation, apoptosis and osteogenic differentiation in periodontitis. METHODS: The periodontitis cell model was constructed by stimulating periodontal ligament stem cells (PDLSCs) with lipopolysaccharide (LPS), and the periodontitis rats were established by ligation. RESULTS: First, we isolated exosomes from the SHED, and we figured out that exosomes secreted by SHED were enriched in miR-92a-3p and the exosomes enhanced proliferation and osteogenic differentiation and reduced apoptosis and inflammatory responses in PDLSCs. In addition, we found that SHED-exosomes alleviated inflammatory effect and elevated the expression of osteogenic-related genes in periodontitis rat model. Moreover, miR-92a-3p targeted downstream Krüppel-Like Transcription Factor 4 (KLF4) and regulated the PI3K/AKT pathway. Finally, our data indicated that upregulation of KLF4 or activation of PI3K/AKT by 740Y-P counteracted the inhibitory effect of SHED-exosomes on periodontitis progression. CONCLUSION: Taken together, our finding revealed that exosomal miR-92a-3p derived from SHED contributed to the alleviation of periodontitis development and progression through inactivating the KLF4/PI3K/AKT signaling pathway, which may provide a potential target for the treatment of periodontitis.

Deciduous teeth from the New Hampshire birth cohort study: Early life environmental and dietary predictors of dentin elements.

BACKGROUND: Sparse research exists on predictors of element concentrations measured in deciduous teeth. OBJECTIVE: To estimate associations between maternal/child characteristics, elements measured in home tap water during pregnancy and element concentrations in the dentin of shed deciduous teeth. METHODS: Our analysis included 152 pregnant person-infant dyads followed from the second trimester through the end of the first postnatal year from the New Hampshire Birth Cohort Study. During pregnancy and early infancy, we collected dietary and sociodemographic information via surveys, measured elements in home tap water, and later collected naturally exfoliated teeth from child participants. We measured longitudinal deposition of elements in dentin using LA-ICP-MS. Multivariable linear mixed models were used to estimate associations between predictors and dentin element concentrations. RESULTS: We measured 12 elements in dentin including those previously reported (Ba, Mn, Pb, Sr, Zn) and less frequently reported (Al, As, Cd, Cu, Hg, Li, and W). A doubling of Pb or Sr concentrations in water was associated with higher dentin Pb or Sr respectively in prenatally formed [9% (95%CI: 3%, 15%); 3% (1%, 6%)] and postnatally formed [10% (2%, 19%); 6% (2%, 10%)] dentin. Formula feeding from birth to 6 weeks or 6 weeks to 4 months was associated with higher element concentrations in postnatal dentin within the given time period as compared to exclusive human milk feeding: Sr: 6 weeks: 61% (36%, 90%) and 4 months: 85% (54%, 121%); Ba: 6 weeks: 35% (3.3%, 77%) and 4 months: 42% (10%, 83%); and Li: 6 weeks: 61% (33%, 95%) and 4 months: 58% (31%, 90%). SIGNIFICANCE: These findings offer insights into predictors of dentin elements and potential confounders in exposure-health outcome relationships during critical developmental periods.

Interventions with pregnant women, new mothers and other primary caregivers for preventing early childhood caries.

BACKGROUND: Dental caries, a common chronic disease of childhood, is associated with adverse health and economic consequences for infants and their families. Socioeconomically disadvantaged children have a higher risk of early childhood caries (ECC). This review updates one published in 2019. OBJECTIVES: To assess the effects of interventions undertaken with pregnant women, new mothers or other primary caregivers of infants in the first year of life, for preventing ECC (from birth to six years). SEARCH METHODS: We searched Cochrane Oral Health's Trials Register, Cochrane Pregnancy and Childbirth's Trials Register, CENTRAL, MEDLINE (Ovid), Embase (Ovid), CINAHL EBSCO, the US National Institutes of Health Ongoing Trials Register (clinicaltrials.gov) and WHO International Clinical Trials Registry Platform (apps.who.int/trialsearch). The latest searches were run on 3 January, 2023. SELECTION CRITERIA: Randomised controlled trials (RCTs) comparing interventions with pregnant women, or new mothers and other primary caregivers of infants in the first year of life, against standard care, placebo or another intervention, reporting on a primary outcome: caries presence in primary teeth, dmfs (decayed, missing, filled primary surfaces index), or dmft (decayed, missing, filled teeth index), in children up to six years of age. Intervention types include clinical, oral health promotion/education (hygiene education, breastfeeding and other dietary advice) and policy or service. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed study eligibility, extracted data, assessed risk of bias, and assessed certainty of evidence (GRADE). MAIN RESULTS: We included 23 RCTs (5 cluster-randomised), involving 25,953 caregivers (mainly mothers) and their children. Fifteen trials assessed oral health education/promotion interventions against standard care. Six trials assessed a clinical intervention for mother dentition, against placebo, or a different type of clinical intervention. Two trials assessed oral health/education promotion plus clinical intervention (for mother's dentition) against standard care. At most, five trials (maximum of 1326 children and 130 mothers) contributed data to any comparison. Enamel-only caries were included in the diagnosis of caries in some studies. For many trials, the risk of bias was unclear due to lack of methodological details reported. In thirteen trials, participants were socioeconomically disadvantaged. No trial indicated receiving funding that was likely to have influenced their results. Oral health education/promotion interventions Child diet and feeding practice advice versus standard care: We observed a probable 15 per cent reduced risk of caries presence in primary teeth with the intervention (RR 0.85, 95% CI 0.75 to 0.97; 3 trials; 782 participants; moderate-certainty evidence), and there may be a slightly lower mean dmfs (MD -0.29, 95% CI -0.58 to 0; 2 trials; 757 participants; low-certainty evidence); however, the evidence is very uncertain regarding the difference between groups in mean dmft (MD -0.90, 95% CI -1.85 to 0.05; 1 trial; 340 participants; very low-certainty evidence). Breastfeeding promotion and support versus standard care: We observed little or no difference between groups in the risk of caries presence in primary teeth (RR 0.96, 95% CI 0.89 to 1.03; 2 trials; 1148 participants; low-certainty evidence) and in mean dmft (MD -0.12, 95% CI -0.59 to 0.36; 2 trials; 652 participants; low-certainty evidence). dmfs was not reported. Child diet advice compared with standard care: We are very uncertain about the effect on the risk of caries presence in primary teeth (RR 1.08, 95% CI 0.34 to 3.37; 1 trial; 148 participants; very low-certainty evidence). dmfs and dmft were not reported. Oral hygiene, child diet and feeding practice advice versus standard care: The evidence is very uncertain about the effect on the risk of caries presence in primary teeth (RR 0.73, 95% CI 0.50 to 1.07; 5 trials; 1326 participants; very low-certainty evidence) and there maybe little to no difference in mean dmfs (MD -0.87, 95% CI -2.18 to 0.43; 2 trials; 657 participants; low-certainty evidence) and mean dmft (MD -0.30, 95% CI -0.96 to 0.36; 1 trial; 187 participants; low-certainty evidence). High-dose versus low-dose vitamin D supplementation during pregnancy: We are very uncertain about the effect on risk of caries presence in primary teeth (RR 0.99, 95% CI 0.70 to 1.41; 1 trial; 496 participants; very low-certainty evidence). dmfs and dmft were not reported. Clinical interventions (for mother dentition) Chlorhexidine (CHX, a commonly prescribed antiseptic agent) or iodine-NaF application and prophylaxis versus placebo: We are very uncertain regarding the difference in risk of caries presence in primary teeth between antimicrobial and placebo treatment for mother dentition (RR 0.97, 95% CI 0.80 to 1.19; 3 trials; 479 participants; very low-certainty evidence). No trial reported dmfs or dmft. Xylitol compared with CHX antimicrobial treatment: We are very uncertain about the effect on caries presence in primary teeth (RR 0.62, 95% CI 0.27 to 1.39; 1 trial, 96 participants; very low-certainty evidence), but we observed there may be a lower mean dmft with xylitol (MD -2.39; 95% CI -4.10 to -0.68; 1 trial, 113 participants; low-certainty evidence). No trial reported dmfs. Oral health education/promotion plus clinical interventions (for mother dentition) Diet and feeding practice advice for infants and young children plus basic dental care for mothers compared with standard care: We are very uncertain about the effect on risk of caries presence in primary teeth (RR 0.44, 95% CI 0.05 to 3.95; 2 trials, 324 participants; very low-certainty evidence) or on mean dmft (1 study, not estimable). No trial reported dmfs. No trials evaluated policy or health service interventions. AUTHORS' CONCLUSIONS: There is moderate-certainty evidence that providing advice on diet and feeding to pregnant women, mothers or other caregivers with children up to the age of one year probably leads to a slightly reduced risk of early childhood caries (ECC). The remaining evidence is low to very-low certainty and is insufficient for determining which, if any, other intervention types and features may be effective for preventing ECC, and in which settings. Large, high-quality RCTs of oral health education/promotion, clinical, and policy and service access interventions, are warranted to determine the effects and relative effects of different interventions and inform practice. We have identified 13 ongoing studies. Future studies should consider if and how effects are modified by intervention features and participant characteristics (including socioeconomic status).

Young small extracellular vesicles rejuvenate replicative senescence by remodeling Drp1 translocation-mediated mitochondrial dynamics.

BACKGROUND: Human mesenchymal stem cells have attracted interest in regenerative medicine and are being tested in many clinical trials. In vitro expansion is necessary to provide clinical-grade quantities of mesenchymal stem cells; however, it has been reported to cause replicative senescence and undefined dysfunction in mesenchymal stem cells. Quality control assessments of in vitro expansion have rarely been addressed in ongoing trials. Young small extracellular vesicles from the remnant pulp of human exfoliated deciduous teeth stem cells have demonstrated therapeutic potential for diverse diseases. However, it is still unclear whether young small extracellular vesicles can reverse senescence-related declines. RESULTS: We demonstrated that mitochondrial structural disruption precedes cellular dysfunction during bone marrow-derived mesenchymal stem cell replication, indicating mitochondrial parameters as quality assessment indicators of mesenchymal stem cells. Dynamin-related protein 1-mediated mitochondrial dynamism is an upstream regulator of replicative senescence-induced dysfunction in bone marrow-derived mesenchymal stem cells. We observed that the application of young small extracellular vesicles could rescue the pluripotency dissolution, immunoregulatory capacities, and therapeutic effects of replicative senescent bone marrow-derived mesenchymal stem cells. Mechanistically, young small extracellular vesicles could promote Dynamin-related protein 1 translocation from the cytoplasm to the mitochondria and remodel mitochondrial disruption during replication history. CONCLUSIONS: Our findings show that Dynamin-related protein 1-mediated mitochondrial disruption is associated with the replication history of bone marrow-derived mesenchymal stem cells. Young small extracellular vesicles from human exfoliated deciduous teeth stem cells alleviate replicative senescence by promoting Dynamin-related protein 1 translocation onto the mitochondria, providing evidence for a potential rejuvenation strategy.