Pulp Stem Cell-Mediated Functional Pulp Regeneration

Enhancing Vasculogenesis in Dental Pulp Development: DPSCs-ECs Communication via FN1-ITGA5 Signaling

BACKGROUND

Dental pulp regeneration therapy is a challenge to achieve early vascularization during treatment. Studying the regulatory mechanisms of vascular formation during human dental pulp development may provide insights for related therapies. In this study, we utilized single-cell sequencing analysis to compare the gene expression of dental pulp stem cells (DPSCs) and vascular endothelial cells (ECs) from developing and mature dental pulps.

METHOD

Immunohistochemistry, Western blot, and real-time polymerase chain reaction (RT-PCR) were used to detect fibronectin 1 (FN1) expression and molecules, such as PI3K/AKT. Cell proliferation assay, scratch assay, tube formation assay and were used to investigate the effects of DPSCs on the vasculogenetic capability of ECs. Additionally, animal experiments involving mice were conducted.

RESULT

The results revealed that DPSCs exist around dental pulp vasculature. FN1 expression was significantly higher in DPSCs from young permanent pulps than mature pulps, promoting HUVEC proliferation, migration, and tube formation via ITGA5 and the downstream PI3K/AKT signaling pathway.

CONCLUSION

Our data indicate that intercellular communication between DPSCs and ECs mediated by FN1-ITGA5 signaling is crucial for vascularizationduring dental pulp development, laying an experimental foundation for future clinical studies.

PDGF-AA guides cell crosstalk between human dental pulp stem cells in vitro via the PDGFR-α/PI3K/Akt axis

AIM

To explore the influence of PDGF-AA on cell communication between human dental pulp stem cells (DPSCs) by characterizing gap junction intercellular communication (GJIC) and its potential biomechanical mechanism.

METHODOLOGY

Quantitative real-time PCR was used to measure connexin family member expression in DPSCs. Cell migration and CCK-8 assays were utilized to examine the influence of PDGF-AA on DPSC migration and proliferation. A scrape loading/dye transfer assay was applied to evaluate GJIC triggered by PDGF-AA, a PI3K/Akt signalling pathway blocker (LY294002) and a PDGFR-α blocker (AG1296). Western blotting and immunofluorescence were used to test the expression and distribution of the Cx43 and p-Akt proteins in DPSCs. Scanning electron microscopy (SEM) and immunofluorescence were used to observe the morphology of GJIC in DPSCs.

RESULTS

PDGF-AA promoted gap junction formation and intercellular communication between human dental pulp stem cells. PDGF-AA upregulates the expression of Cx43 to enhance gap junction formation and intercellular communication. PDGF-AA binds to PDGFR-α and activates PI3K/Akt signalling to regulate cell communication.

CONCLUSIONS

This research demonstrated that PDGF-AA can enhance Cx43-mediated GJIC in DPSCs via the PDGFR-α/PI3K/Akt axis, which provides new cues for dental pulp regeneration from the perspective of intercellular communication.

Strontium-Containing Piezoelectric Biofilm Promotes Dentin Tissue Regeneration

It remains an obstacle to induce the regeneration of hard dentin tissue in clinical settings. To overcome this, a P(VDF-TrFE) piezoelectric film with 2 wt% SrCl2 addition is designed. The biofilm shows a high flexibility, a harmonious biocompatibility, and a large piezoelectric d33 coefficient of 14 pC N-1, all contributing to building an electric microenvironment that favor the recruitment of dental pulp stem cells (DPSCs) and their differentiation into odontoblasts during normal chewing, speaking, etc. On the other hand, the strontium ions can be gradually released from the film, thus promoting DPSC odonto-differentiation. In vivo experiments also demonstrate that the film induces the release of dentin minerals and regeneration of dentin tissue. In the large animal dentin defect models, this piezoelectric film induces in situ dentin tissue formation effectively over a period of three months. This study illustrates a therapeutic potential of the piezoelectric film to improve dentin tissue repair in clinical settings.

Effects of Innervation on Angiogenesis and Osteogenesis in Bone and Dental Tissue Engineering

The repair and regeneration of critical-sized bone defects remain an urgent challenge. Bone tissue engineering represents an exciting solution for regeneration of large bone defects. Recently, the importance of innervation in tissue-engineered bone regeneration has been increasingly recognized. The cross talk between nerve and bone provides important clues for bone repair and regeneration. Furthermore, the promotion of angiogenesis by innervation can accelerate new bone formation. However, the mechanisms involved in the promotion of vascular and bone regeneration by the nervous system have not yet been established. In addition, simultaneous neurogenesis and vascularization in bone tissue engineering have not been fully investigated. This article represents the first review on the effects of innervation in enhancing angiogenesis and osteogenesis in bone and dental tissue engineering. Cutting-edge research on the effects of innervation through biomaterials on bone and dental tissue repairs is reviewed. The effects of various nerve-related factors and cells on bone regeneration are discussed. Finally, novel clinical applications of innervation for bone, dental, and craniofacial tissue regeneration are also examined.

Inhibition of soluble epoxide hydrolase enhances the dentin-pulp complex regeneration mediated by crosstalk between vascular endothelial cells and dental pulp stem cells

BACKGROUND

Revascularization and restoration of normal pulp-dentin complex are important for tissue-engineered pulp regeneration. Recently, a unique periodontal tip-like endothelial cells subtype (POTCs) specialized to dentinogenesis was identified. We have confirmed that TPPU, a soluble epoxide hydrolase (sEH) inhibitor targeting epoxyeicosatrienoic acids (EETs) metabolism, promotes bone growth and regeneration by angiogenesis and osteogenesis coupling. We hypothesized that TPPU could also promote revascularization and induce POTCs to contribute to pulp-dentin complex regeneration. Here, we in vitro and in vivo characterized the potential effect of TPPU on the coupling of angiogenesis and odontogenesis and investigated the relevant mechanism, providing new ideas for pulp-dentin regeneration by targeting sEH.

METHODS

In vitro effects of TPPU on the proliferation, migration, and angiogenesis of dental pulp stem cells (DPSCs), human umbilical vein endothelial cells (HUVECs) and cocultured DPSCs and HUVECs were detected using cell counting kit 8 (CCK8) assay, wound healing, transwell, tube formation and RT-qPCR. In vivo, Matrigel plug assay was performed to outline the roles of TPPU in revascularization and survival of grafts. Then we characterized the VEGFR2 + POTCs around odontoblast layer in the molar of pups from C57BL/6 female mice gavaged with TPPU. Finally, the root segments with DPSCs mixed with Matrigel were implanted subcutaneously in BALB/c nude mice treated with TPPU and the root grafts were isolated for histological staining.

RESULTS

In vitro, TPPU significantly promoted the migration and tube formation capability of cocultured DPSCs and HUVECs. ALP and ARS staining and RT-qPCR showed that TPPU promoted the osteogenic and odontogenic differentiation of cultured cells, treatment with an anti-TGF-β blocking antibody abrogated this effect. Knockdown of HIF-1α in HUVECs significantly reversed the effect of TPPU on the expression of angiogenesis, osteogenesis and odontogenesis-related genes in cocultured cells. Matrigel plug assay showed that TPPU increased VEGF/VEGFR2-expressed cells in transplanted grafts. TPPU contributed to angiogenic-odontogenic coupling featured by increased VEGFR2 + POTCs and odontoblast maturation during early dentinogenesis in molar of newborn pups from C57BL/6 female mice gavaged with TPPU. TPPU induced more dental pulp-like tissue with more vessels and collagen fibers in transplanted root segment.

CONCLUSIONS

TPPU promotes revascularization of dental pulp regeneration by enhancing migration and angiogenesis of HUVECs, and improves odontogenic differentiation of DPSCs by TGF-β. TPPU boosts the angiogenic-odontogenic coupling by enhancing VEGFR2 + POTCs meditated odontoblast maturation partly via upregulating HIF-1α, which contributes to increasing pulp-dentin complex for tissue-engineered pulp regeneration.

Exosome-based engineering strategies for the diagnosis and treatment of oral and maxillofacial diseases

Oral and maxillofacial diseases are one of the most prevalent diseases in the world, which not only seriously affect the health of patients' oral and maxillofacial tissues, but also bring serious economic and psychological burdens to patients. Therefore, oral and maxillofacial diseases require effective treatment. Traditional treatments have limited effects. In recent years, nature exosomes have attracted increasing attention due to their ability to diagnose and treat diseases. However, the application of nature exosomes is limited due to low yield, high impurities, lack of targeting, and high cost. Engineered exosomes can be endowed with better comprehensive therapeutic properties by modifying exosomes of parent cells or directly modifying exosomes, and biomaterial loading exosomes. Compared with natural exosomes, these engineered exosomes can achieve more effective diagnosis and treatment of oral and maxillary system diseases, and provide reference and guidance for clinical application. This paper reviews the engineering modification methods of exosomes and the application of engineered exosomes in oral and maxillofacial diseases and looks forward to future research directions.

Exosomes derived from odontogenic stem cells: Its role in the dentin-pulp complex

Odontogenic stem cells originate from cranial neural crest cells and offer unique advantages in the regeneration of dentin-pulp complex. There is increasing evidence that stem cells exert their biological functions mainly through exosome-based paracrine effects. Exosomes contain DNA, RNA, proteins, metabolites, etc., which can play a role in intercellular communication and have similar therapeutic potential to stem cells. In addition, compared with stem cells, exosomes also have the advantages of good biocompatibility, high drug carrying capacity, easy to obtain, and few side effects. Odontogenic stem cell-derived exosomes mainly affect the regeneration of the dentin-pulp complex by regulating processes such as dentintogenesis, angiogenesis, neuroprotection and immunomodulation. This review aimed to describe "cell-free therapies" based on odontogenic stem cell-derived exosomes, which aim to regenerate the dentin-pulp complex.

Advances and challenges in regenerative dentistry: A systematic review of calcium phosphate and silicate-based materials on human dental pulp stem cells

Conventional dentistry faces limitations in preserving tooth health due to the finite lifespan of restorative materials. Regenerative dentistry, utilizing stem cells and bioactive materials, offers a promising approach for regenerating dental tissues. Human dental pulp stem cells (hDPSCs) and bioactive materials like calcium phosphate (CaP) and silicate-based materials have shown potential for dental tissue regeneration. This systematic review aims to investigate the effects of CaP and silicate-based materials on hDPSCs through in vitro studies published since 2015. Following the PRISMA guidelines, a comprehensive search strategy was implemented in PubMed MedLine, Cochrane, and ScienceDirect databases. Eligibility criteria were established using the PICOS scheme. Data extraction and risk of bias (RoB) assessment were conducted, with the included studies assessed for bias using the Office of Health and Translation (OHAT) RoB tool. The research has been registered at OSF Registries. Ten in vitro studies met the eligibility criteria out of 1088 initial studies. Methodological heterogeneity and the use of self-synthesized biomaterials with limited generalizability were observed in the included study. The findings highlight the positive effect of CaP and silicate-based materials on hDPSCs viability, adhesion, migration, proliferation, and differentiation. While the overall RoB assessment indicated satisfactory credibility of the reviewed studies, the limited number of studies and methodological heterogeneity pose challenges for quantitative research. In conclusion, this systematic review provides valuable insights into the effects of CaP and silicate-based materials on hDPSCs. Further research is awaited to enhance our understanding and optimize regenerative dental treatments using bioactive materials and hDPSCs, which promise to improve patient outcomes.

In vitro response of dental pulp stem cells to dural substitute grafts: Analysis of cytocompatibility and bioactivity

AIM

The objective of this study was to assess and compare the cytocompatibility of decellularized porcine small intestine submucosal dural graft from Biodesign (BD) and polyester urethane-based Neuro-Patch (NP) dural substitute with the mineral trioxide aggregate (MTA) and the cyanoacrylate-based Histoacryl surgical adhesive. Furthermore, the study evaluated the inflammatory response and osteogenic differentiation of human dental pulp stem cells (hDPSCs) when cultured in direct contact with the dural substitutes in comparison with MTA.

METHODOLOGY

The viability of hDPSCs in direct contact with the tested materials was investigated in vitro by a CCK-8 assay. Additionally, the effects of dural substitutes and MTA on the expression of the inflammatory mediator interleukin-6 (IL-6) was investigated via enzyme-linked immunosorbent assay (ELISA), whilst effects on the differentiation were evaluated using alizarin red staining, alkaline phosphatase staining, ELISA and energy-dispersive X-ray elemental mapping.

RESULTS

The dural substitutes were cytocompatible and promoted cellular adhesion. The Histoacryl and MTA demonstrated cytotoxicity in fresh preparations but showed a more favourable cellular reaction when set. Investigations of biological activity indicated that dural substitute membranes did not induce an inflammatory response or osteogenic differentiation of hDPSCs. In contrast, MTA induced the expression of IL-6 and alkaline phosphatase activity contributing to enhanced differentiation and mineralization.

CONCLUSIONS

The dural substitute membranes showed cytocompatibility, did not provoke an inflammatory response and maintained the stemness of hDPSCs better than MTA. Additionally, the set Histoacryl surgical adhesive demonstrated good biocompatibility. Taken together, these results highlight the potential use of dural substitutes in regenerative endodontic procedures as coronal barriers alternative to MTA to reduce the incidence of intracanal calcifications.

Roles of DNA methylation in influencing the functions of dental-derived mesenchymal stem cells

OBJECTIVE

DNA methylation as intensively studied epigenetic regulatory mechanism exerts pleiotropic effects on dental-derived mesenchymal stem cells (DMSCs). DMSCs have self-renewal and multidifferentiation potential. Here, this review aims at summarizing the research status about application of DMSCs in tissue engineering and clarifying the roles of DNA methylation in influencing the functions of DMSCs, with expectation of paving the way for its in-depth exploration in tissue engineering.

METHOD

The current research status about influence of DNA methylation in DMSCs was acquired by MEDLINE (through PubMed) and Web of Science using the keywords 'DNA methylation', 'dental-derived mesenchymal stem cells', 'dental pulp stem cells', 'periodontal ligament stem cells', 'dental follicle stem cells', 'stem cells from the apical papilla', 'stem cells from human exfoliated deciduous teeth', and 'gingival-derived mesenchymal stem cells'.

RESULTS

This review indicates DNA methylation affects DMSCs' differentiation and function through inhibiting or enhancing the expression of specific gene resulted by DNA methylation-related genes or relevant inhibitors.

CONCLUSION

DNA methylation can influence DMSCs in aspects of osteogenesis, adipogenesis, immunomodulatory function, and so on. Yet, the present studies about DNA methylation in DMSCs commonly focus on dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs). Little has been reported for other DMSCs.

Hsa-miR-27b-5p suppresses the osteogenic and odontogenic differentiation of stem cells from human exfoliated deciduous teeth via targeting BMPR1A: An ex vivo study

AIM

Recently, miR-27b-5p was shown to be abundantly expressed in extracellular vehicles (EVs) from the inflammatory microenvironment. This study determined the role of miR-27b-5p in regulating osteogenic and odontogenic differentiation of stem cells from human exfoliated deciduous teeth (SHEDs) and further examined the regulatory mechanism of bone morphogenetic protein receptor type-1A (BMPR1A).

METHODOLOGY

Characteristics of SHEDs and SHEDs-EVs derived from SHEDs were evaluated respectively. The expression of miR-27b-5p in SHEDs and EVs was detected during osteo-induction. Mechanically, SHEDs were treated with miR-27b-5p mimics or an inhibitor, and the osteogenic/odontogenic differentiation and proliferation were assessed. Bioinformatic analysis and luciferase reporter were utilized for target gene prediction and verification. Finally, BMPR1A-overexpressed plasmids were transfected into SHEDs to investigate the participation of the BMPR1A/SMAD4 pathway. Data were analysed using Student's t-test, one-way analysis of variance and Chi-square test.

RESULTS

MiR-27b-5p was expressed in both SHEDs and EVs and was significantly increased at the initial stage of differentiation and then decreased in a time-dependent manner (p < .01). Upregulation of miR-27b-5p significantly suppressed osteogenic/odontogenic differentiation of SHEDs and inhibited proliferation (p < .05), whereas inhibition of miR-27b-5p enhanced the differentiation (p < .05). Dual-luciferase reporter assay and pull-down assay confirmed the binding site between miR-27b-5p and BMPR1A (p < .05). The overexpression of BMPR1A rescued the effect of miR-27b-5p, while contributed to the decrease of pluripotency (p < .05). Additionally, miR-27b-5p maintained pluripotency in BMPR1A-overexpressed SHEDs (p < .05).

CONCLUSIONS

MiR-27b-5p in SHEDs/EVs was inversely associated with differentiation and suppressed the osteogenic and odontogenic differentiation of SHEDs and maintained the pluripotency of SHEDs partly by shuttering BMPR1A-targeting BMP signalling. Theoretically, inhibition of miR-27b-5p represents a potential strategy to promote osteanagenesis and dentinogenesis. However, miR-27b-5p capsuled EVs might maintain cell pluripotency and self-renewal for non-cell-targeted therapy.

DLP printed hDPSC-loaded GelMA microsphere regenerates dental pulp and repairs spinal cord

Dental pulp regeneration is ideal for irreversible pulp or periapical lesions, and in situ stem cell therapy is one of the most effective therapies for pulp regeneration. In this study, we provided an atlas of the non-cultured and monolayer cultured dental pulp cells with single-cell RNA sequencing and analysis. Monolayer cultured dental pulp cells cluster more closely together than non-cultured dental pulp cells, suggesting a lower heterogeneous population with relatively consistent clusters and similar cellular composition. We successfully fabricated hDPSC-loaded microspheres by layer-by-layer photocuring with a digital light processing (DLP) printer. These hDPSC-loaded microspheres have improved stemness and higher multi-directional differentiation potential, including angiogenic, neurogenic, and odontogenic differentiation. The hDPSC-loaded microspheres could promote spinal cord regeneration in rat spinal cord injury models. Moreover, in heterotopic implantation tests on nude mice, CD31, MAP2, and DSPP immunofluorescence signals were observed, implying the formation of vascular, neural, and odontogenetic tissues. In situ experiments in minipigs demonstrated highly vascularized dental pulp and uniformly arranged odontoblast-like cells in root canals of incisors. In short, hDPSC-loaded microspheres can promote full-length dental pulp regeneration at the root canals' coronal, middle, and apical sections, particularly for blood vessels and nerve formation, which is a promising therapeutic strategy for necrotic pulp.

Mesenchymal condensation in tooth development and regeneration: a focus on translational aspects of organogenesis

The teeth are vertebrate-specific, highly specialized organs performing fundamental functions of mastication and speech, the maintenance of which is crucial for orofacial homeostasis and is further linked to systemic health and human psychosocial well-being. However, with limited ability for self-repair, the teeth can often be impaired by traumatic, inflammatory, and progressive insults, leading to high prevalence of tooth loss and defects worldwide. Regenerative medicine holds the promise to achieve physiological restoration of lost or damaged organs, and in particular an evolving framework of developmental engineering has pioneered functional tooth regeneration by harnessing the odontogenic program. As a key event of tooth morphogenesis, mesenchymal condensation dictates dental tissue formation and patterning through cellular self-organization and signaling interaction with the epithelium, which provides a representative to decipher organogenetic mechanisms and can be leveraged for regenerative purposes. In this review, we summarize how mesenchymal condensation spatiotemporally assembles from dental stem cells (DSCs) and sequentially mediates tooth development. We highlight condensation-mimetic engineering efforts and mechanisms based on ex vivo aggregation of DSCs, which have achieved functionally robust and physiologically relevant tooth regeneration after implantation in animals and in humans. The discussion of this aspect will add to the knowledge of development-inspired tissue engineering strategies and will offer benefits to propel clinical organ regeneration.

PER2 Promotes Odontoblastic/Osteogenic Differentiation of Dental Pulp Stem Cells by Modulating Mitochondrial Metabolism

Human dental pulp stem cells (hDPSCs) possess remarkable self-renewal and multilineage differentiation ability. PER2, an essential circadian molecule, regulates various physiological processes. Evidence suggests that circadian rhythm and PER2 participate in physiological functions of DPSCs. However, the influence of PER2 on DPSCs' differentiation remains largely unknown. This study aimed to explore the effect and potential mechanism of PER2 on hDPSCs' differentiation. Dental pulp tissues were extracted, and hDPSCs were cultured for in vitro and in vivo experiments. Dorsal subcutaneous transplantation was performed in 6-week-old male BALB/c mice. The hDPSCs' odontoblastic/osteogenic differentiation was assessed, and mitochondrial metabolism was evaluated. The results indicated PER2 expression increasing during hDPSCs' odontoblastic/osteogenic differentiation. Gain- and loss-of function studies confirmed that PER2 promoted alkaline phosphatase (ALP) activity, mineralized nodules deposition, mRNA expression of DSPP, DMP1, COL1A1 and protein expression of DSPP and DMP1 in hDPSCs. Furthermore, PER2 enhanced collagen deposition, osteodentine-like tissue formation and DSPP expression in vivo. Mitochondrial metabolic evaluation aimed to investigate the mechanism of PER2-mediated hDPSC odontoblastic/osteogenic differentiation, which showed that PER2 increased ATP synthesis, elevated mitochondrial membrane potential and changed expression of proteins regulating mitochondrial dynamics. This study demonstrated that PER2 promoted hDPSCs' odontoblastic/osteogenic differentiation, which involved mitochondrial metabolic change.

Epithelium-derived SCUBE3 promotes polarized odontoblastic differentiation of dental mesenchymal stem cells and pulp regeneration

BACKGROUND

Signal peptide-CUB-EGF domain-containing protein 3 (SCUBE3), a secreted multifunctional glycoprotein whose transcript expression is restricted to the tooth germ epithelium during the development of embryonic mouse teeth, has been demonstrated to play a crucial role in the regulation of tooth development. Based on this, we hypothesized that epithelium-derived SCUBE3 contributes to bio-function in dental mesenchymal cells (Mes) via epithelium-mesenchyme interactions.

METHODS

Immunohistochemical staining and a co-culture system were used to reveal the temporospatial expression of the SCUBE3 protein during mouse tooth germ development. In addition, human dental pulp stem cells (hDPSCs) were used as a Mes model to study the proliferation, migration, odontoblastic differentiation capacity, and mechanism of rhSCUBE3. Novel pulp-dentin-like organoid models were constructed to further confirm the odontoblast induction function of SCUBE3. Finally, semi-orthotopic animal experiments were performed to explore the clinical application of rhSCUBE3. Data were analysed using one-way analysis of variance and t-tests.

RESULTS

The epithelium-derived SCUBE3 translocated to the mesenchyme via a paracrine pathway during mouse embryonic development, and the differentiating odontoblasts in postnatal tooth germ subsequently secreted the SCUBE3 protein via an autocrine mechanism. In hDPSCs, exogenous SCUBE3 promoted cell proliferation and migration via TGF-β signalling and accelerated odontoblastic differentiation via BMP2 signalling. In the semi-orthotopic animal experiments, we found that SCUBE3 pre-treatment-induced polarized odontoblast-like cells attached to the dental walls and had better angiogenesis performance.

CONCLUSION

SCUBE3 protein expression is transferred from the epithelium to mesenchyme during embryonic development. The function of epithelium-derived SCUBE3 in Mes, including proliferation, migration, and polarized odontoblastic differentiation, and their mechanisms are elaborated for the first time. These findings shed light on exogenous SCUBE3 application in clinic dental pulp regeneration.

Hydrogels for Oral Tissue Engineering: Challenges and Opportunities

Oral health is crucial to daily life, yet many people worldwide suffer from oral diseases. With the development of oral tissue engineering, there is a growing demand for dental biomaterials. Addressing oral diseases often requires a two-fold approach: fighting bacterial infections and promoting tissue growth. Hydrogels are promising tissue engineering biomaterials that show great potential for oral tissue regeneration and drug delivery. In this review, we present a classification of hydrogels commonly used in dental research, including natural and synthetic hydrogels. Furthermore, recent applications of these hydrogels in endodontic restorations, periodontal tissues, mandibular and oral soft tissue restorations, and related clinical studies are also discussed, including various antimicrobial and tissue growth promotion strategies used in the dental applications of hydrogels. While hydrogels have been increasingly studied in oral tissue engineering, there are still some challenges that need to be addressed for satisfactory clinical outcomes. This paper summarizes the current issues in the abovementioned application areas and discusses possible future developments.

Effects of phase-transited lysozyme on adhesion, migration and odontogenic differentiation of human dental pulp cells: An in vitro study

AIM

To explore the effects of phase-transited lysozyme (PTL) coated dentine slices on cell adhesion, migration and odontogenic differentiation of human dental pulp cells (HDPCs).

METHODOLOGY

Cell growth and cell cycle analysis were conducted to verify the biocompatibility of PTL for HDPCs. Cell adhesion, cell morphology and proliferation were explored by DiI staining, Scanning electron microscopy and MTT assay. Cell migration was investigated by Transwell assay. The effects of PTL on odontogenesis and mineralization of HDPCs were assessed by real-time quantitative polymerase chain reaction and Western blot. The mineralization of HDPCs was evaluated by Alizarin red staining. HDPCs were isolated from extracted third molars. The level of statistically significant difference was accepted at p < .05.

RESULTS

PTL showed no negative effect on cell cycle of HDPCs and compared with the blank group, HDPCs labelled with DiI staining showed significantly more adhered cells at 48 h (p < .05), extending cell processes and more finger-like or reticular pseudopodia on PTL-coated dentine slices. The results of MTT and Transwell assay showed that PTL promoted the proliferation (p < .05) and migration (p < .01) of HDPCs, respectively. Compared with the blank group, the gene expression of dentine sialophosphoprotein (DSPP), osteopontin and bone sialoprotein in HDPCs cultured on PTL was significantly upregulated on day 3 and 7 (p < .05), while the protein expression of DSPP showed no significant change on both day 7 and day 14. Alizarin red staining showed that PTL promoted more mineralization nodules formation of HDPCs (p < .05).

CONCLUSIONS

PTL promoted the adhesion, proliferation and migration of HDPCs on dentine slices, and positively affected odontogenic differentiation and mineralization of HDPCs.

Immunomodulatory properties of mesenchymal stem cells/dental stem cells and their therapeutic applications

Mesenchymal stem/stromal cells (MSCs) are widely distributed in the body and play essential roles in tissue regeneration and homeostasis. MSCs can be isolated from discarded tissues, expanded in vitro and used as therapeutics for autoimmune diseases and other chronic disorders. MSCs promote tissue regeneration and homeostasis by primarily acting on immune cells. At least six different types of MSCs have been isolated from postnatal dental tissues and have remarkable immunomodulatory properties. Dental stem cells (DSCs) have been demonstrated to have therapeutic effects on several systemic inflammatory diseases. Conversely, MSCs derived from nondental tissues such as the umbilical cord exhibit great benefits in the management of periodontitis in preclinical studies. Here, we discuss the main therapeutic uses of MSCs/DSCs, their mechanisms, extrinsic inflammatory cues and the intrinsic metabolic circuitries that govern the immunomodulatory functions of MSCs/DSCs. Increased understanding of the mechanisms underpinning the immunomodulatory functions of MSCs/DSCs is expected to aid in the development of more potent and precise MSC/DSC-based therapeutics.

Mesenchymal stem cells: Emerging concepts and recent advances in their roles in organismal homeostasis and therapy

Stem cells play a crucial role in re-establishing homeostasis in the body, and the search for mechanisms by which they interact with the host to exert their therapeutic effects remains a key question currently being addressed. Considering their significant regenerative/therapeutic potential, research on mesenchymal stem cells (MSCs) has experienced an unprecedented advance in recent years, becoming the focus of extensive works worldwide to develop cell-based approaches for a variety of diseases. Initial evidence for the effectiveness of MSCs therapy comes from the restoration of dynamic microenvironmental homeostasis and endogenous stem cell function in recipient tissues by systemically delivered MSCs. The specific mechanisms by which the effects are exerted remain to be investigated in depth. Importantly, the profound cell-host interplay leaves persistent therapeutic benefits that remain detectable long after the disappearance of transplanted MSCs. In this review, we summarize recent advances on the role of MSCs in multiple disease models, provide insights into the mechanisms by which MSCs interact with endogenous stem cells to exert therapeutic effects, and refine the interconnections between MSCs and cells fused to damaged sites or differentiated into functional cells early in therapy.

Bone Differentiation Ability of CD146-Positive Stem Cells from Human Exfoliated Deciduous Teeth

Regenerative therapy for tissues by mesenchymal stem cell (MSCs) transplantation has received much attention. The cluster of differentiation (CD)146 marker, a surface-antigen of stem cells, is crucial for angiogenic and osseous differentiation abilities. Bone regeneration is accelerated by the transplantation of CD146-positive deciduous dental pulp-derived mesenchymal stem cells contained in stem cells from human exfoliated deciduous teeth (SHED) into a living donor. However, the role of CD146 in SHED remains unclear. This study aimed to compare the effects of CD146 on cell proliferative and substrate metabolic abilities in a population of SHED. SHED was isolated from deciduous teeth, and flow cytometry was used to analyze the expression of MSCs markers. Cell sorting was performed to recover the CD146-positive cell population (CD146+) and CD146-negative cell population (CD146-). CD146 + SHED without cell sorting and CD146-SHED were examined and compared among three groups. To investigate the effect of CD146 on cell proliferation ability, an analysis of cell proliferation ability was performed using BrdU assay and MTS assay. The bone differentiation ability was evaluated using an alkaline phosphatase (ALP) stain after inducing bone differentiation, and the quality of ALP protein expressed was examined. We also performed Alizarin red staining and evaluated the calcified deposits. The gene expression of ALP, bone morphogenetic protein-2 (BMP-2), and osteocalcin (OCN) was analyzed using a real-time polymerase chain reaction. There was no significant difference in cell proliferation among the three groups. The expression of ALP stain, Alizarin red stain, ALP, BMP-2, and OCN was the highest in the CD146+ group. CD146 + SHED had higher osteogenic differentiation potential compared with SHED and CD146-SHED. CD146 contained in SHED may be a valuable population of cells for bone regeneration therapy.

Fabrication of an exosome-loaded thermosensitive chitin-based hydrogel for dental pulp regeneration

Injective thermosensitive hydrogels are considered promising scaffolds to trigger dental pulp regeneration in devitalized human teeth. In this study, we developed a hydroxypropyl chitin (HPCH)/chitin whisker (CW) thermosensitive hydrogel with enhanced mechanical properties and biological activities. Exosomes can serve as biomimetic tools for tissue engineering, but the rapid clearance of unconjugated exosomes in vivo limits their therapeutic effects. To address this challenge, exosomes were isolated from human pulp stem cells (hDPSCs) and directly embedded into the HPCH/CW pre-gel to form an exosome-loaded hydrogel (HPCH/CW/Exo). The exosome-loaded thermosensitive hydrogel can be easily injected into an irregular endodontic space and gelated in situ. In vitro cell experiments proved that the delivery of exosomes significantly improved the ability of hydrogels to promote odontogenesis and angiogenesis. Meanwhile, in vivo animal experiments revealed the formation of new dental pulp-like tissues in an implanted tooth root model. Therefore, the proposed hydrogel provides a great potential alternative to traditional root canal therapy in dental clinics.

Injectable decellularized dental pulp matrix-functionalized hydrogel microspheres for endodontic regeneration

The sufficient imitation of tissue structures and components represents an effective and promising approach for tissue engineering and regenerative medicine applications. Dental pulp disease is one of the most common oral diseases, although functional pulp regeneration remains challenging. Herein, we propose a strategy that employs hydrogel microspheres incorporated with decellularized dental pulp matrix-derived bioactive factors to simulate a pulp-specific three-dimensional (3D) microenvironment. The dental pulp microenvironment-specific microspheres constructed by this regenerative strategy exhibited favorable plasticity, biocompatibility, and biological performances. Human dental pulp stem cells (hDPSCs) cultured on the constructed microspheres exhibited enhanced pulp-formation ability in vitro. Furthermore, the hDPSCs-microcarriers achieved the regeneration of pulp-like tissue and new dentin in a semi-orthotopic model in vivo. Mechanistically, the decellularized pulp matrix-derived bioactive factors mediated the multi-directional differentiation of hDPSCs to regenerate the pulp tissue by eliciting the secretion of crucial bioactive cues. Our findings demonstrated that a 3D dental pulp-specific microenvironment facilitated by hydrogel microspheres and dental pulp-specific bioactive factors regenerated the pulp-dentin complex and could be served as a promising treatment option for dental pulp disease. STATEMENT OF SIGNIFICANCE: Injectable bioscaffolds are increasingly used for regenerative endodontic treatment. Despite their success related to their ability to load stem cells, bioactive factors, and injectability, conventional bulk bioscaffolds have drawbacks such as ischemic necrosis in the central region. Various studies have shown that ischemic necrosis in the central region can be corrected by injectable hydrogel microspheres. Unfortunately, pristine microspheres or microspheres without dental pulp-specific bioactive factor would oftentimes fail to regulate stem cells fates in dental pulp multi-directional differentiation. Our present study reported the biofabrication of dental pulp-derived decellularized matrix functionalized gelatin microspheres, which contained dental pulp-specific bioactive factors and have the potential application in endodontic regeneration.

Extracellular Vesicles for Dental Pulp and Periodontal Regeneration

Extracellular vesicles (EVs) are lipid bound particles derived from their original cells, which play critical roles in intercellular communication through their cargoes, including protein, lipids, and nucleic acids. According to their biogenesis and release pathway, EVs can be divided into three categories: apoptotic vesicles (ApoVs), microvesicles (MVs), and small EVs (sEVs). Recently, the role of EVs in oral disease has received close attention. In this review, the main characteristics of EVs are described, including their classification, biogenesis, biomarkers, and components. Moreover, the therapeutic mechanism of EVs in tissue regeneration is discussed. We further summarize the current status of EVs in pulp/periodontal tissue regeneration and discuss the potential mechanisms. The therapeutic potential of EVs in pulp and periodontal regeneration might involve the promotion of tissue regeneration and immunomodulatory capabilities. Furthermore, we highlight the current challenges in the translational use of EVs. This review would provide valuable insights into the potential therapeutic strategies of EVs in dental pulp and periodontal regeneration.

EVL Promotes Osteo-/Odontogenic Differentiation of Dental Pulp Stem Cells via Activating JNK Signaling Pathway

Objective

Human dental pulp stem cells (hDPSCs) were recognized as a suitable and promising source of stem cells in dental pulp regeneration. However, the mechanism by which hDPSCs differentiation into osteo-/odontogenic lineage remains unclear. Ena/VASP-like protein (EVL) has been found to be involved in diverse biological processes. In this study, we explored the role and underlying mechanism of EVL in osteo-/odontogenic differentiation of hDPSCs.

Methods

Expression of EVL was detected in hDPSCs by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot (WB) analyses during osteo-/odontogenic differentiation. The function of EVL in osteo-/odontogenic differentiation and involvement of MAPK signaling pathways were evaluated by alkaline phosphatase (ALP) staining and activity, alizarin red staining (ARS), and qRT-PCR and western blot analyses.

Results

The expression of EVL was upregulated during osteo-/odontogenic differentiation of hDPSCs. Overexpression of EVL significantly increased osteo-/odontogenic capacity of hDPSCs, which was reflected in increased alkaline phosphatase (ALP) staining, ALP activity, mineralized nodule formation, and the expressions of genes related to osteo-/odontogenic differentiation, while downregulation of EVL inhibited it. In addition, EVL activated the JNK pathway and phosphorylation of p38 MAPK during differentiation procedure of hDPSCs. The EVL-enhanced differentiation of DPSCs was suppressed by blocking the JNK pathway, rather than the p38 MAPK pathway.

Conclusion

EVL promotes the osteo-/odontogenic differentiation of hDPSCs by activating the JNK pathway, providing a future target for osteo-/odontogenic differentiation and dental pulp regeneration.

Cannabidiol Rescues TNF-α-Inhibited Proliferation, Migration, and Osteogenic/Odontogenic Differentiation of Dental Pulp Stem Cells

Strategies to promote dental pulp stem cells (DPSCs) functions including proliferation, migration, pro-angiogenic effects, and odontogenic/osteogenic differentiation are in urgent need to restore pulpitis-damaged dentin/pulp regeneration and DPSCs-based bone tissue engineering applications. Cannabidiol (CBD), an active component of Cannabis sativa has shown anti-inflammation, chemotactic, anti-microbial, and tissue regenerative potentials. Based on these facts, this study aimed to analyze the effect of CBD on DPSCs proliferation, migration, and osteogenic/odontogenic differentiation in basal and inflammatory conditions. Highly pure DPSCs with characteristics of mesenchymal stem cells (MSCs) were successfully isolated, as indicated by the results of flowcytometry and multi-lineage (osteogenic, adipogenic, and chondrogenic) differentiation potentials. Among the concentration tested (0.1-12.5 µM), CBD (2.5 μM) showed the highest anabolic effect on the proliferation and osteogenic/odontogenic differentiation of DPSCs. Pro-angiogenic growth factor VEGF mRNA expression was robustly higher in CBD-treated DPSCs. CBD also prompted the migration of DPSCs and CBD receptor CB1 and CB2 expression in DPSCs. TNF-α inhibited the viability, migration, and osteogenic/odontogenic differentiation of DPSCs and CBD reversed these effects. CBD alleviated the TNF-α-upregulated expression of pro-inflammatory cytokines TNF-α, interleukin (IL)-1β, and IL-6 in DPSCs. In conclusion, our results indicate the possible application of CBD on DPSCs-based dentin/pulp and bone regeneration.

Creating a Microenvironment to Give Wings to Dental Pulp Regeneration-Bioactive Scaffolds

Dental pulp and periapical diseases make patients suffer from acute pain and economic loss. Although root canal therapies, as demonstrated through evidence-based medicine, can relieve symptoms and are commonly employed by dentists, it is still difficult to fully restore a dental pulp's nutrition, sensory, and immune-regulation functions. In recent years, researchers have made significant progress in tissue engineering to regenerate dental pulp in a desired microenvironment. With breakthroughs in regenerative medicine and material science, bioactive scaffolds play a pivotal role in creating a suitable microenvironment for cell survival, proliferation, and differentiation, following dental restoration and regeneration. This article focuses on current challenges and novel perspectives about bioactive scaffolds in creating a microenvironment to promote dental pulp regeneration. We hope our readers will gain a deeper understanding and new inspiration of dental pulp regeneration through our summary.

Combination of Dental-Capping Agents with Low Level Laser Therapy Promotes Proliferation of Stem Cells from Apical Papilla

Background: Direct pulp capping is a vital pulp therapy, which stimulates differentiation of stem cells from apical papilla (SCAPs). SCAPs have multipotential capacity to differentiate into types of cells, contributing to the regeneration of tissues. Objective: Considering the promising effects of dental-capping materials, we aim to investigate the effect of dental dressing materials combined with laser therapy on the percentage of SCAP viability and the consequent dental regeneration capacity. Methods: We collected two immature third molar teeth and isolated SCAPs through collagenase type I enzymatic activity. Isolated SCAPs were then cultured with Dulbecco's modified Eagle's medium and α-minimum essential medium enriched with 15% and 10% fetal bovine serum, respectively. After reaching 70-80% confluency, cells were seeded in a 96-well plate and then treated with mineral trioxide aggregate (MTA), enamel matrix derivative (EMD), biodentine, and low level laser therapy (LLLT) alone and in combination for 24, 48, and 168 h. After that, cell survival rate was assessed using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay. Results: We found that combination of MTA, EMD, and LLLT as well as that of biodentine, EMD, and LLLT could lead to significant increase of SCAP viability as compared with other treatment groups. Combination of MTA and biodentine with EMD could also show increased level of SCAP proliferation and viability. However, MTA and biodentine alone reduced SCAP survival rate in all time points. Conclusions: Our conclusion is that LLLT can serve as an enhancer of SCAP proliferation and differentiation rate when added to dental-capping agents such as MTA, EMD, and biodentine. Thus, LLLT combination with effective capping materials will serve as a promising option for dental tissue repair.

Decellularized rat submandibular gland as an alternative scaffold for dental pulp regeneration

Introduction: Decellularized extracellular matrix has been recognized as an optimal scaffold for dental pulp regeneration. However, the limited amount of native dental pulp tissue restricts its clinical applications. The submandibular gland shares some basic extracellular matrix components and characteristics with dental pulp. However, whether decellularized submandibular gland extracellular matrix (DSMG) can be used as an alternative scaffold for dental pulp regenerative medicine is unclear. Methods: Thus, we successfully decellularized the whole rat submandibular gland and human dental pulp, and then conducted in vitro and in vivo studies to compare the properties of these two scaffolds for dental pulp regeneration. Results: Our results showed that extracellular matrix of the submandibular gland had great similarities in structure and composition with that of dental pulp. Furthermore, it was confirmed that the DSMG could support adhesion and proliferation of dental pulp stem cells in vitro. In vivo findings revealed that implanted cell-seeded DSMG formed a vascularized dental pulp-like tissue and expressed markers involved in dentinogenesis and angiogenesis. Discussion: In summary, we introduced a novel accessible biological scaffold and validated its effectiveness as an extracellular matrix-based tissue engineering scaffold for dental pulp regenerative therapy.

Stage-specific requirement for METTL3-dependent m6A modification during dental pulp stem cell differentiation

BACKGROUND

N⁶-methyladenosine (m⁶A) is the most prevalent epigenetic modification in eukaryotic messenger RNAs and plays a critical role in cell fate transition. However, it remains to be elucidated how m⁶A marks functionally impact the transcriptional cascades that orchestrate stem cell differentiation. The present study focuses on the biological function and mechanism of m⁶A methylation in dental pulp stem cell (DPSC) differentiation.

METHODS

m⁶A RNA immunoprecipitation sequencing was utilized to assess the m⁶A-mRNA landscape during DPSC differentiation. Ectopic transplantation of DPSCs in immunodeficient mice was conducted to verify the in vitro findings. RNA sequencing and m⁶A RNA immunoprecipitation sequencing were combined to identify the candidate targets. RNA immunoprecipitation and RNA/protein stability of Noggin (NOG) were evaluated. The alteration in poly(A) tail was measured by 3'-RACE and poly(A) tail length assays.

RESULTS

We characterized a dynamic m⁶A-mRNA landscape during DPSC mineralization with increasing enrichment in the 3' untranslated region (UTR). Methyltransferase-like 3 (METTL3) was identified as the key m⁶A player, and METTL3 knockdown disrupted functional DPSC differentiation. Moreover, METTL3 overexpression enhanced DPSC mineralization. Increasing m⁶A deposition in the 3' UTR restricted NOG expression, which is required for DPSC mineralization. This stage-specific m⁶A methylation and destabilization of NOG was suppressed by METTL3 knockdown only in differentiated DPSCs. Furthermore, METTL3 promotes the degradation of m⁶A-tagged NOG by shortening the poly(A) tail length in the differentiated stage.

CONCLUSIONS

Our results address an essential role of dynamic m⁶A signaling in the temporal control of DPSC differentiation and provide new insight into epitranscriptomic mechanisms in stem cell-based therapy.

Easily attainable and low immunogenic stem cells from exfoliated deciduous teeth enhanced the in vivo bone regeneration ability of gelatin/bioactive glass microsphere composite scaffolds

Repair of critical-size bone defects remains a considerable challenge in the clinic. The most critical cause for incomplete healing is that osteoprogenitors cannot migrate to the central portion of the defects. Herein, stem cells from exfoliated deciduous teeth (SHED) with the properties of easy attainability and low immunogenicity were loaded into gelatin/bioactive glass (GEL/BGM) scaffolds to construct GEL/BGM + SHED engineering scaffolds. An in vitro study showed that BGM could augment the osteogenic differentiation of SHED by activating the AMPK signaling cascade, as confirmed by the elevated expression of osteogenic-related genes, and enhanced ALP activity and mineralization formation in SHED. After implantation in the critical bone defect model, GEL/BGM + SHED scaffolds exhibited low immunogenicity and significantly enhanced new bone formation in the center of the defect. These results indicated that GEL/BGM + SHED scaffolds present a new promising strategy for critical-size bone healing.

Neural Regeneration in Regenerative Endodontic Treatment: An Overview and Current Trends

Pulpal and periapical diseases are the most common dental diseases. The traditional treatment is root canal therapy, which achieves satisfactory therapeutic outcomes-especially for mature permanent teeth. Apexification, pulpotomy, and pulp revascularization are common techniques used for immature permanent teeth to accelerate the development of the root. However, there are obstacles to achieving functional pulp regeneration. Recently, two methods have been proposed based on tissue engineering: stem cell transplantation, and cell homing. One of the goals of functional pulp regeneration is to achieve innervation. Nerves play a vital role in dentin formation, nutrition, sensation, and defense in the pulp. Successful neural regeneration faces tough challenges in both animal studies and clinical trials. Investigation of the regeneration and repair of the nerves in the pulp has become a serious undertaking. In this review, we summarize the current understanding of the key stem cells, signaling molecules, and biomaterials that could promote neural regeneration as part of pulp regeneration. We also discuss the challenges in preclinical or clinical neural regeneration applications to guide deep research in the future.

Regeneration of the Pulp Tissue: Cell Homing versus Cell Transplantation Approach: A Systematic Review

BACKGROUND

The main objective of this systematic review was to compare the apical healing, root maturation and histological characteristics of teeth treated with cell-based versus cell-free techniques.

METHODS

The methodology of this review was based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. A literature search strategy was carried out on PubMed, EMBASE and the Web of Science databases. The last search was done on 1 August 2021. Articles written in languages other than English were excluded. Two researchers independently selected the studies and extracted the data. As no randomized clinical trials were available, animal studies were included.

RESULTS

In total, 26 studies were included in the systematic review: 22 articles only researched the cell-free technique, 3 articles compared the cell-based to the cell-free technique, and 1 article compared the cell-based technique to apexification. In terms of apical healing, qualitative analysis of the data suggested that there seems to be no significant difference between cell-free and cell-based techniques. The results regarding tooth maturation are contradictory. The main difference between the cell-free and the cell-based techniques seems to be the histology of the treated tooth. The cell-free technique seems to result in cementum-like, bone-like or periodontal ligament-like tissue. One study, on the other hand, found that the cell-based technique resulted in regeneration of the whole pulp with an odontoblast layer, connective tissue, blood vessels and neuronal tissue.

CONCLUSIONS

Currently, the number of randomized clinical trials on this topic are very scarce. This is probably due to the limited infrastructure and lack of resources to apply the cell-based technique. Even though both techniques seem to be promising for clinical application, long-term data need to be provided regarding the healing and reparative patterns.

The Inhibition of the Inducible Nitric Oxide Synthase Enhances the DPSC Mineralization under LPS-Induced Inflammation

Nitric oxide (NO) is a key messenger in physiological and pathological processes in mammals. An excessive NO production is associated with pathological conditions underlying the inflammation response as a trigger. Among others, dental pulp inflammation results from the invasion of dentin by pathogenic bacteria. Vital functions of pulp mesenchymal stem cells (DPSCs, dental pulp stem cells), such as mineralization, might be affected by the inducible NOS (iNOS) upregulation. In this context, the iNOS selective inhibition can be considered an innovative therapeutic strategy to counteract inflammation and to promote the regeneration of the dentin-pulp complex. The present work aims at evaluating two acetamidines structurally related to the selective iNOS inhibitor 1400W, namely CM544 and FAB1020, in a model of LPS-stimulated primary DPSCs. Our data reveal that CM544 and even more FAB1020 are promising anti-inflammatory compounds, decreasing IL-6 secretion by enhancing CD73 expression-levels, a protein involved in innate immunity processes and thus confirming an immunomodulatory role of DPSCs. In parallel, cell mineralization potential is retained in the presence of compounds as well as VEGF secretion, and thus their angiogenetic potential. Data presented lay the ground for further investigation on the anti-inflammatory potential of acetamidines selectively targeting iNOS in a clinical context.

Apoptotic vesicles activate autophagy in recipient cells to induce angiogenesis and dental pulp regeneration

Extracellular vesicles (EVs) derived from living cells play important roles in donor cell-induced recipient tissue regeneration. Although numerous studies have found that cells undergo apoptosis after implantation in an ischemic-hypoxic environment, the roles played by the EVs released by apoptotic cells are largely unknown. In this study, we obtained apoptotic vesicles (apoVs) derived from human deciduous pulp stem cells and explored their effects on the dental pulp regeneration process. Our work showed that apoVs were ingested by endothelial cells (ECs) and elevated the expression of angiogenesis-related genes, leading to pulp revascularization and tissue regeneration. Furthermore, we found that, at the molecular level, apoV-carried mitochondrial Tu translation elongation factor was transported and regulated the angiogenic activation of ECs via the transcription factor EB-autophagy pathway. In a beagle model of dental pulp regeneration in situ, apoVs recruited endogenous ECs and facilitated the formation of dental-pulp-like tissue rich in blood vessels. These findings revealed the significance of apoptosis in tissue regeneration and demonstrated the potential of using apoVs to promote angiogenesis in clinical applications.

Metformin carbon nanodots promote odontoblastic differentiation of dental pulp stem cells by pathway of autophagy

Human dental pulp stem cells (hDPSCs) have been a focus of pulp regeneration research because of their excellent odontogenic potential and availability. Applying the odontoblastic differentiation of hDPSCs to tooth regeneration has been challenging. Metformin-based carbon nanodots (MCDs) were synthesized and characterized to investigate their effects in vitro on odontoblastic hDPSC differentiation and the underlying mechanism. MCDs were synthesized by a hydrothermal treatment method and characterized using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The biocompatibility and fluorescence properties of the MCDs in Dulbecco’s modified Eagle’s medium high-glucose culture medium and the in vitro odontogenic potential and related mechanism of the bioactive nanomaterial was explored. TEM images showed that MCDs were spherical in shape with a size of approximately 5.9 nm. MCDs showed biological safety in cell viability, apoptosis, and fluorescence labelling ability at a concentration up to 200 μg/ml in vitro. The presence of MCDs facilitated high-efficiency odontogenic differentiation of hDPSCs by promoting odontogenic gene and protein expression. Moreover, MCDs promoted odontoblastic hDPSC differentiation via autophagy. MCDs are capable of activating autophagy and enhancing the odontogenic differentiation of hDPSCs by upregulating odontoblast gene marker (DMP1, DSPP, RUNX2, and SP7) and protein (DSPP and DMP1) expression.

Bioinductive and anti-inflammatory properties of Propolis and Biodentine on SHED

Objectives

This study aimed to evaluate and compare the cell viability, differentiation potential and anti-inflammatory potential of propolis and Biodentine™ on stem cells isolated from human exfoliated deciduous teeth (SHED).

Materials and methods

SHED were segregated and cultured from the dental pulp of children after therapeutic extraction. Microculture Tetrazolium Assay (MTT) assay was carried out for assessing cell proliferation potential of propolis and Biodentine at different concentrations. As per the results from cell proliferation assay, cell differentiation potential of SHED was evaluated at concentration of 12.5 μg/ml using Alizarin Red staining. The anti-inflammatory potential of test materials was evaluated using gelatin zymography by detecting MMP-2 and MMP-9.

Results

The maximum cell proliferation percentage of SHED treated with propolis and Biodentine was observed at a concentration of 12.5 μg/ml, on day 7, 14 and 21 with Biodentine having maximum cell proliferation potential followed by propolis. SHED treated with Biodentine showed maximum cell differentiation on day 7 (107.16), 14 (106.29) and 21 (107.72). However, anti-inflammatory activity against MMP-2 was 95 % with propolis and 85 % with Biodentine and whereas, against MMP-9 it was 65 % for propolis and 47 % for Biodentine.

Conclusion

Propolis shows comparable cell viability, cell proliferation and differentiation potential on SHED when compared to Biodentine. It also exhibits better invitro anti-inflammatory activity on SHED compared to Biodentine. Further studies are warranted to validate the application of propolis as an effective and economical alternative biocompatible agent to Biodentine for vital pulp therapies.

Cells and material-based strategies for regenerative endodontics

<p class = "Abstract" style = "margin: 0 cm; line-height: 32px; font-size: 12 pt; font-family: "Times New Roman", serif; color: rgb(0, 0, 0); "><span lang = "EN-US">The carious process leads to inflammation of pulp tissue. Current care options include root canal treatment or apexification. These procedures, however, result in the loss of tooth vitality, sensitivity, and healing. Pulp capping and dental pulp regeneration are continually evolving techniques to regenerate pulp tissue, avoiding necrosis and loss of vitality. Many studies have successfully employed stem/progenitor cell populations, revascularization approaches, scaffolds or material-based strategies for pulp regeneration. Here we outline advantages and disadvantages of different methods and techniques which are currently being used in the field of regenerative endodontics. We also summarize recent findings on efficacious peptide-based materials which target the dental niche.<o:p></o:p></span></p>

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Pulp infection necessitates removal of necrotic, inflamed and infected tissue.

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Materials used clinically are inert (such as gutta percha, mineral trioxide aggregate).

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Recent developments in materials (angiogenic hydrogels, stem cell composites) have tuneable bioactivity.

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Dental pulp regeneration may now be possible through the use of bioactive systems, that guide regeneration.

Bone Tissue Engineering in the Treatment of Bone Defects

Bones play an important role in maintaining exercise and protecting organs. Bone defect, as a common orthopedic disease in clinics, can cause tremendous damage with long treatment cycles. Therefore, the treatment of bone defect remains as one of the main challenges in clinical practice. Today, with increased incidence of bone disease in the aging population, demand for bone repair material is high. At present, the method of clinical treatment for bone defects including non-invasive therapy and invasive therapy. Surgical treatment is the most effective way to treat bone defects, such as using bone grafts, Masquelet technique, Ilizarov technique etc. In recent years, the rapid development of tissue engineering technology provides a new treatment strategy for bone repair. This review paper introduces the current situation and challenges of clinical treatment of bone defect repair in detail. The advantages and disadvantages of bone tissue engineering scaffolds are comprehensively discussed from the aspect of material, preparation technology, and function of bone tissue engineering scaffolds. This paper also summarizes the 3D printing technology based on computer technology, aiming at designing personalized artificial scaffolds that can accurately fit bone defects.

Metabolic Remodeling Impacts the Epigenetic Landscape of Dental Mesenchymal Stem Cells

Epigenetic regulation can dynamically adjust the gene expression program of cell fate decision according to the cellular microenvironment. Emerging studies have shown that metabolic activities provide fundamental components for epigenetic modifications and these metabolic-sensitive epigenetic events dramatically impact the cellular function of stem cells. Dental mesenchymal stem cells are promising adult stem cell resource for in situ injury repair and tissue engineering. In this review, we discuss the impact of metabolic fluctuations on epigenetic modifications in the oral and maxillofacial regions. The principles of the metabolic link to epigenetic modifications and the interaction between metabolite substrates and canonical epigenetic events in dental mesenchymal stem cells are summarized. The coordination between metabolic pathways and epigenetic events plays an important role in cellular progresses including differentiation, inflammatory responses, and aging. The metabolic-epigenetic network is critical for expanding our current understanding of tissue homeostasis and cell fate decision and for guiding potential therapeutic approaches in dental regeneration and infectious diseases.

Biomolecule-Mediated Therapeutics of the Dentin–Pulp Complex: A Systematic Review

The aim of this systematic review was to evaluate the application of potential therapeutic signaling molecules on complete dentin-pulp complex and pulp tissue regeneration in orthotopic and ectopic animal studies. A search strategy was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement in the MEDLINE/PubMed database. Animal studies evaluating the application of signaling molecules to pulpectomized teeth for pulp tissue or dentin-pulp complex regeneration were included. From 2530 identified records, 18 fulfilled the eligibility criteria and were subjected to detailed qualitative analysis. Among the applied molecules, basic fibroblast growth factor, vascular endothelial growth factor, bone morphogenetic factor-7, nerve growth factor, and platelet-derived growth factor were the most frequently studied. The clinical, radiographical and histological outcome measures included healing of periapical lesions, root development, and apical closure, cellular recolonization of the pulp space, ingrowth of pulp-like connective tissue (vascularization and innervation), mineralized dentin-like tissue formation along the internal dentin walls, and odontoblast-like cells in contact with the internal dentin walls. The results indicate that signaling molecules play an important role in dentin/pulp regeneration. However, further studies are needed to determine a more specific subset combination of molecules to achieve greater efficiency towards the desired tissue engineering applications.

Decellularized Dental Pulp, Extracellular Vesicles, and 5-Azacytidine: A New Tool for Endodontic Regeneration

Dental pulp is a major component of the dental body that serves to maintain the tooth life and function. The aim of the present work was to develop a system that functions as a growth-permissive microenvironment for dental pulp regeneration using a decellularized dental pulp (DDP) matrix, 5-Aza-2′-deoxycytidine (5-Aza), and Extracellular Vesicles (EVs) derived from human Dental Pulp Stem Cells (hDPSCs). Human dental pulps extracted from healthy teeth, scheduled to be removed for orthodontic purpose, were decellularized and then recellularized with hDPSCs. The hDPSCs were seeded on DDP and maintained under different culture conditions: basal medium (CTRL), EVs, 5-Aza, and EVs+-5-Aza. Immunofluorescence staining and Western blot analyses were performed to evaluate the proteins’ expression related to dentinogenesis, such as ALP, RUNX2, COL1A1, Vinculin, DMP1, and DSPP. Protein contents found in the DDP recellularized with hDPSCs were highly expressed in samples co-treated with EVs and 5-Aza compared to other culture conditions. This study developed a DDP matrix loaded by hDPSCs in co-treatment with EVs, which might enhance the dentinogenic differentiation with a high potentiality for endodontic regeneration.

Dental Pulp Stem Cell Heterogeneity: Finding Superior Quality "Needles" in a Dental Pulpal "Haystack" for Regenerative Medicine-Based Applications

Human dental pulp stem/stromal cells (hDPSCs) derived from the permanent secondary dentition are recognised to possess certain advantageous traits, which support their potential use as a viable source of mesenchymal stem/stromal cells (MSCs) for regenerative medicine-based applications. However, the well-established heterogeneous nature of hDPSC subpopulations, coupled with their limited numbers within dental pulp tissues, has impeded our understanding of hDPSC biology and the translation of sufficient quantities of these cells from laboratory research, through successful therapy development and clinical applications. This article reviews our current understanding of hDPSC biology and the evidence underpinning the molecular basis of their heterogeneity, which may be exploited to distinguish individual subpopulations with specific or superior characteristics for regenerative medicine applications. Pertinent unanswered questions which still remain, regarding the developmental origins, hierarchical organisation, and stem cell niche locations of hDPSC subpopulations and their roles in hDPSC heterogeneity and functions, will further be explored. Ultimately, a greater understanding of how key features, such as specific cell surface, senescence and other relevant genes, and protein and metabolic markers, delineate between hDPSC subpopulations with contrasting stemness, proliferative, multipotency, immunomodulatory, anti-inflammatory, and other relevant properties is required. Such knowledge advancements will undoubtedly lead to the development of novel screening, isolation, and purification strategies, permitting the routine and effective identification, enrichment, and expansion of more desirable hDPSC subpopulations for regenerative medicine-based applications. Furthermore, such innovative measures could lead to improved cell expansion, manufacture, and banking procedures, thereby supporting the translational development of hDPSC-based therapies in the future.

Dental mesenchymal stromal/stem cells in different microenvironments— implications in regenerative therapy

Current research data reveal microenvironment as a significant modifier of physical functions, pathologic changes, as well as the therapeutic effects of stem cells. When comparing regeneration potential of various stem cell types used for cytotherapy and tissue engineering, mesenchymal stem cells (MSCs) are currently the most attractive cell source for bone and tooth regeneration due to their differentiation and immunomodulatory potential and lack of ethical issues associated with their use. The microenvironment of donors and recipients selected in cytotherapy plays a crucial role in regenerative potential of transplanted MSCs, indicating interactions of cells with their microenvironment indispensable in MSC-mediated bone and dental regeneration. Since a variety of MSC populations have been procured from different parts of the tooth and tooth-supporting tissues, MSCs of dental origin and their achievements in capacity to reconstitute various dental tissues have gained attention of many research groups over the years. This review discusses recent advances in comparative analyses of dental MSC regeneration potential with regards to their tissue origin and specific microenvironmental conditions, giving additional insight into the current clinical application of these cells.

Mechanistically Scoping Cell-Free and Cell-Dependent Artificial Scaffolds in Rebuilding Skeletal and Dental Hard Tissues

Rebuilding mineralized tissues in skeletal and dental systems remains costly and challenging. Despite numerous demands and heavy clinical burden over the world, sources of autografts, allografts, and xenografts are far limited, along with massive risks including viral infections, ethic crisis, and so on. Per such dilemma, artificial scaffolds have emerged to provide efficient alternatives. To date, cell-free biomimetic mineralization (BM) and cell-dependent scaffolds have both demonstrated promising capabilities of regenerating mineralized tissues. However, BM and cell-dependent scaffolds have distinctive mechanisms for mineral genesis, which makes them methodically, synthetically, and functionally disparate. Herein, these two strategies in regenerative dentistry and orthopedics are systematically summarized at the level of mechanisms. For BM, methodological and theoretical advances are focused upon; and meanwhile, for cell-dependent scaffolds, it is demonstrated how scaffolds orchestrate osteogenic cell fate. The summary of the experimental advances and clinical progress will endow researchers with mechanistic understandings of artificial scaffolds in rebuilding hard tissues, by which better clinical choices and research directions may be approached.

In vitro evaluation of periapical lesion-derived stem cells for dental pulp tissue engineering

Dental pulp tissue engineering is a promising alternative treatment for pulpitis and periapical periodontitis, and dental pulp stem cells (DPSCs) are considered to be the gold standard for dental seed cell research. Periapical lesions harbor mesenchymal stem cells with the capacity for self-renewal and multilineage differentiation. However, it remains unknown whether these periapical lesion-derived stem cells (PLDSCs) are suitable for dental pulp tissue engineering. To investigate this possibility, PLDSCs and DPSCs were isolated using the tissue outgrowth method and cultured under identical conditions. We then performed in vitro experiments to investigate their biological characteristics. Our results indicate that PLDSCs proliferate actively in vitro and exhibit similar morphology, immunophenotype and multilineage differentiation ability as DPSCs. Simultaneously, PLDSCs exhibit stronger migrative ability and express more vascular endothelial growth factor and glial cell line-derived neurotrophic factor than DPSCs, and PLDSC-derived conditioned medium was more effective in tube formation assay. The mRNA expression levels of immunomodulatory genes HLA-G, IDO and ICAM-1 were also higher in PLDSCs. However, regarding osteo/odontogenic differentiation, PLDSCs showed weaker alkaline phosphatase staining and lower calcified nodule formation compared to DPSCs, as well as lower expression of ALP, RUNX2 and DSPP, as confirmed by a quantitative RT-PCR. The osteo/odontogenic protein expression levels of DSPP, RUNX2, DMP1 and SP7 were also higher in DPSCs. The present study demonstrates that PLDSCs demonstrate potential use as seed cells for dental pulp regeneration, especially for achieving enhanced neurovascularization.