Characterisation of dental pulp stem cells: A new horizon for tissue regeneration?

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.

The potential therapeutic roles of dental pulp stem cells in spinal cord injury

Spinal cord injury (SCI) can lead to serious functional disorders, which have serious impacts on patients and society. The current traditional treatments of SCI are not effective the injured spinal cord is difficult to repair and regenerate. In recent years, stem cell transplantation for the treatment of SCI has been a hot research topic. Dental pulp stem cells have strong abilities of self-renewal and multi-directional differentiation, and have been applied for tissue engineering and regenerative medicine. And dental pulp stem cells have certain advantages in neuro-regenetation, bringing new hope to biotherapy for SCI. This article reviews the characteristics of dental pulp stem cells and their research progress in the treatment of SCI.

Chemically modified microRNA delivery via DNA tetrahedral frameworks for dental pulp regeneration

Dental pulp regeneration is a promising strategy for addressing tooth disorders. Incorporating this strategy involves the fundamental challenge of establishing functional vascular networks using dental pulp stem cells (DPSCs) to support tissue regeneration. Current therapeutic approaches lack efficient and stable methods for activating DPSCs. In the study, we used a chemically modified microRNA (miRNA)-loaded tetrahedral-framework nucleic acid nanostructure to promote DPSC-mediated angiogenesis and dental pulp regeneration. Incorporating chemically modified miR-126-3p into tetrahedral DNA nanostructures (miR@TDNs) represents a notable advancement in the stability and efficacy of miRNA delivery into DPSCs. These nanostructures enhanced DPSC proliferation, migration, and upregulated angiogenesis-related genes, enhancing their paracrine signaling effects on endothelial cells. This enhanced effect was substantiated by improvements in endothelial cell tube formation, migration, and gene expression. Moreover, in vivo investigations employing matrigel plug assays and ectopic dental pulp transplantation confirmed the potential of miR@TDNs in promoting angiogenesis and facilitating dental pulp regeneration. Our findings demonstrated the potential of chemically modified miRNA-loaded nucleic acid nanostructures in enhancing DPSC-mediated angiogenesis and supporting dental pulp regeneration. These results highlighted the promising role of chemically modified nucleic acid-based delivery systems as therapeutic agents in regenerative dentistry and tissue engineering.

Determining Factors in the Success of Direct Pulp Capping: A Systematic Review

AIM

To elucidate the factors that determine the success of direct pulp capping (DPC) in permanent teeth with pulp exposure due to dental caries.

MATERIALS AND METHODS

A comprehensive electronic search from 1980 to 2023 across PubMed, Scopus, and ISI Web databases was conducted using specific keywords and MeSH terms in Q1 or Q2 journals. Only prospective/retrospective clinical studies in English on 15 or more human permanent teeth with carious pulpal exposure treated with DPC agents-mineral trioxide aggregate (MTA), Biodentine, or calcium hydroxide with a rubber dam and minimum 1-year follow-up, were considered. The factors retrieved and analyzed were based on study design, patient age, sample size, type of cavity, exposure size and location, pulp diagnosis, solutions to achieve hemostasis, hemostasis time, capping material, restoration type, follow-up period, methods of evaluation, and overall success.

REVIEW RESULTS

Out of 680 articles, only 16 articles were selected for the present systematic review on application of the selection criteria. A wide age range of patients from 6 to 88 years were considered among these studies with sample sizes ranging from 15 to 245 teeth with reversible pulpitis being the predominant diagnosis of the cases. Mineral trioxide aggregate as a capping material was evaluated in 4 studies as a lone agent, while compared with other capping agents such as biodentine or calcium hydroxide in 7 studies. The follow-up period ranged from 9 days to nearly 80 months. While both clinical and radiographic evaluation was carried out in all studies, cold testing dominated the clinical tests while IOPR was the common radiograph considered. Mineral trioxide aggregate success rate was higher and similar to biodentine than calcium hydroxide.

CONCLUSION

Direct pulp capping has a high and predictable success rate in permanent teeth with carious exposure to reversible and irreversible pulpitis. Currently, mineral trioxide aggregate and biodentine have better long-term results in DPC than calcium hydroxide, hence, they should be used as an alternative to calcium hydroxide. Definitive restoration within a short period improves long-term prognosis.

CLINICAL SIGNIFICANCE

The significance of this review lies in its provision of evidence-based information on the effectiveness of DPC and the factors that influence its success. By considering these factors, clinicians can optimize treatment outcomes and improve the long-term prognosis of the treated teeth. This systematic review serves as a valuable resource for clinicians and researchers in the field of endodontics. How to cite this article: Gomez-Sosa JF, Granone-Ricella M, Rosciano-Alvarez M, et al. Determining Factors in the Success of Direct Pulp Capping: A Systematic Review. J Contemp Dent Pract 2024;25(4):392-401.

Osteoblastic differentiation and changes in the redox state in pulp stem cells by laser treatment

The aim of this study was to determine the effect of low-level laser therapy (LLLT) on cell proliferation, mitochondrial membrane potential changes (∆Ψm), reactive oxygen species (ROS), and osteoblast differentiation of human dental pulp stem cells (hDPSCs). These cells were irradiated with 660- and 940-nm lasers for 5 s, 50 s, and 180 s. Cell proliferation was assessed using the resazurin assay, cell differentiation by RUNX2 and BMP2 expression, and the presence of calcification nodules using alizarin-red S staining. ROS was determined by the dichlorofluorescein-diacetate technique and changes in ∆Ψm by the tetramethylrhodamine-ester assay. Data were analyzed by a Student's t-test and Mann-Whitney U test. The 940-nm wavelength for 5 and 50 s increased proliferation at 4 days postirradiation. After 8 days, a significant decrease in proliferation was observed in all groups. Calcification nodules were evident in all groups, with a greater staining intensity in cells treated with a 940-nm laser for 50 s, an effect that correlated with increased RUNX2 and BMP2 expression. ROS production and Δψm increased independently of irradiation time. In conclusion, photobiomodulation (PBM) with LLLT induced morphological changes and reduced cell proliferation rate, which was associated with osteoblastic differentiation and increased ROS and Δψm, independent of wavelength and time.

A review of the therapeutic potential of dental stem cells as scaffold-free models for tissue engineering application

In the realm of regenerative medicine, tissue engineering has introduced innovative approaches to facilitate tissue regeneration. Specifically, in pulp tissue engineering, both scaffold-based and scaffold-free techniques have been applied. Relevant articles were meticulously chosen from PubMed, Scopus, and Google Scholar databases through a comprehensive search spanning from October 2022 to December 2022. Despite the inherent limitations of scaffolding, including inadequate mechanical strength for hard tissues, insufficient vents for vessel penetration, immunogenicity, and suboptimal reproducibility-especially with natural polymeric scaffolds-scaffold-free tissue engineering has garnered significant attention. This methodology employs three-dimensional (3D) cell aggregates such as spheroids and cell sheets with extracellular matrix, facilitating precise regeneration of target tissues. The choice of technique aside, stem cells play a pivotal role in tissue engineering, with dental stem cells emerging as particularly promising resources. Their pluripotent nature, non-invasive extraction process, and unique properties render them highly suitable for scaffold-free tissue engineering. This study delves into the latest advancements in leveraging dental stem cells and scaffold-free techniques for the regeneration of various tissues. This paper offers a comprehensive summary of recent developments in the utilization of dental stem cells and scaffold-free methods for tissue generation. It explores the potential of these approaches to advance tissue engineering and their effectiveness in therapies aimed at tissue regeneration.

Therapeutic Potential of Oral-Derived Mesenchymal Stem Cells in Retinal Repair

The retina has restricted regeneration ability to recover injured cell layer because of reduced production of neurotrophic factors and increased inhibitory molecules against axon regrowth. A diseased retina could be regenerated by repopulating the damaged tissue with functional cell sources like mesenchymal stem cells (MSCs). The cells are able to release neurotrophic factors (NFs) to boost axonal regeneration and cell maintenance. In the current study, we comprehensively explore the potential of various types of stem cells (SCs) from oral cavity as promising therapeutic options in retinal regeneration. The oral MSCs derived from cranial neural crest cells (CNCCs) which explains their broad neural differentiation potential and secret rich NFs. They are comprised of dental pulp SCs (DPSCs), SCs from exfoliated deciduous teeth (SHED), SCs from apical papilla (SCAP), periodontal ligament-derived SCs (PDLSCs), gingival MSCs (GMSCs), and dental follicle SCs (DFSCs). The Oral MSCs are becoming a promising source of cells for cell-free or cell-based therapeutic approach to recover degenerated retinal. These cells have various mechanisms of action in retinal regeneration including cell replacement and the paracrine effect. It was demonstrated that they have more neuroprotective and neurotrophic effects on retinal cells than immediate replacement of injured cells in retina. This could be the reason that their therapeutic effects would be weakened over time. It can be concluded that neuronal and retinal regeneration through these cells is most likely due to their NFs that dramatically suppress oxidative stress, inflammation, and apoptosis. Although, oral MSCs are attractive therapeutic options for retinal injuries, more preclinical and clinical investigations are required.

Potential of dental pulp stem cells and their products in promoting peripheral nerve regeneration and their future applications

Peripheral nerve injury (PNI) seriously affects people's quality of life. Stem cell therapy is considered a promising new option for the clinical treatment of PNI. Dental stem cells, particularly dental pulp stem cells (DPSCs), are adult pluripotent stem cells derived from the neuroectoderm. DPSCs have significant potential in the field of neural tissue engineering due to their numerous advantages, such as easy isolation, multidifferentiation potential, low immunogenicity, and low transplant rejection rate. DPSCs are extensively used in tissue engineering and regenerative medicine, including for the treatment of sciatic nerve injury, facial nerve injury, spinal cord injury, and other neurodegenerative diseases. This article reviews research related to DPSCs and their advantages in treating PNI, aiming to summarize the therapeutic potential of DPSCs for PNI and the underlying mechanisms and providing valuable guidance and a foundation for future research.

Evaluation of the Efficacy of Human Dental Pulp Stem Cell Transplantation in Sprague-Dawley Rats with Sensorial Neural Hearing Loss

OBJECTIVES

 The purpose of the present study was to evaluate the efficacy of spiral ganglion neuron (SGN) regeneration after dental pulp stem cell (DPSC) transplantation in a rat sensorineural hearing loss (HL) model.

MATERIALS AND METHODS

 Sham or experimental HL was induced in adult Sprague-Dawley rats by cochlear round window surgery. An HL rat model was established with a single 10 mM ouabain intratympanic injection. After 7 days, the rats received DPSCs, stem cells from human exfoliated deciduous teeth (SHED), or culture medium in the sutural area to establish four groups: sham, HL-DPSC, HL-SHED, and HL-medium. Histological analyses were performed at 4, 7, and 10 weeks after transplantation, and the number of SGNs, specific SGN protein expression, and the function of SGNs were evaluated.

STATISTICAL ANALYSIS

 Data were statistically by MS Excel and SPSS v.15.0. Intergroup level of significance was determined via a one-way analysis of variance and Duncan's multiple range test with 95% confidence intervals.

RESULTS

 New SGN formation was observed in the HL-DPSC and HL-SHED rat groups. The number of SGNs was significantly higher in the HL-DPSC and HL-SHED groups than in the HL-medium group over 4 to 10-week survival period. HL-DPSC rats exhibited higher SGN density compared with that in HL-SHED group, which was statistically significant at week 10. The regenerated SGNs expressed cochlear wiring regulator GATA-binding-protein 3. Moreover, the SGNs from the HL-DPSC group also exhibited a higher expression of synaptic vesicle protein and regulated action potential-dependent neurotransmitter release compared with SGNs from the HL-SHED group.

CONCLUSIONS

 Our findings suggest that DPSCs and SHED repair and regenerate SGNs in rat HL model. Dental pulp stem cells represent a promising treatment strategy for restoring damage to the sensory circuits associated with deafness.

Selection of Mechanical Fragmentation Methods Based on Enzyme-Free Preparation of Decellularized Adipose-Derived Matrix

BACKGROUND

The decellularized adipose-derived matrix (DAM) has emerged as a promising biomaterial for inducing adipose tissue regeneration. Various methods have been employed to produce DAM, among which the enzyme-free method is a relatively recent preparation technique. The mechanical fragmentation step plays a crucial role in determining the efficacy of the enzyme-free preparation.

METHODS

The adipose tissue underwent fragmentation through the application of ultrasonication, homogenization, and freeze ball milling. This study compared the central temperature of the mixture immediately following crushing, the quantity of oil obtained after centrifugation, and the thickness of the middle layer. Fluorescence staining was utilized to compare the residual cell activity of the broken fat in the middle layer, while electron microscopy was employed to assess the integrity and properties of the adipocytes among the three methods. The primary products obtained through the three methods were subsequently subjected to processing using the enzyme-free method DAM. The assessment of degreasing and denucleation of DAM was conducted through HE staining, oil red staining, and determination of DNA residues. Subsequently, the ultrasonication-DAM (U-DAM) and homogenation-DAM (H-DAM) were implanted bilaterally on the back of immunocompromised mice, and a comparative analysis of their adipogenic and angiogenic effects in vivo was performed.

RESULTS

Oil discharge following ultrasonication and homogenization was significantly higher compared to that observed after freeze ball milling (p < 0.001), despite the latter exhibiting the lowest center temperature (p < 0.001). The middle layer was found to be thinnest after ultrasonication (p < 0.001), and most of the remaining cells were observed to be dead following fragmentation. Except for DAM obtained through freeze ball milling, DAM obtained through ultrasonication and homogenization could be completely denucleated and degreased. In the in vivo experiment, the first adipocytes were observed in U-DAM as early as 1 week after implantation, but not in H-DAM. After 8 weeks, a significant number of adipocytes were regenerated in both groups, but the U-DAM group demonstrated a more efficient adipose regeneration than in H-DAM (p = 0.0057).

CONCLUSIONS

Ultrasonication and homogenization are effective mechanical fragmentation methods for breaking down adipocytes at the initial stage, enabling the production of DAM through an enzyme-free method that facilitates successful regeneration of adipose tissues in vivo. Furthermore, the enzyme-free method, which is based on the ultrasonication pre-fragmentation approach, exhibits superior performance in terms of denucleation, degreasing, and the removal of non-adipocyte matrix components, thereby resulting in the highest in vivo adipogenic induction efficiency.

Molecules Inducing Dental Stem Cells Differentiation and Bone Regeneration: State of the Art

Teeth include mesenchymal stem cells (MSCs), which are multipotent cells that promote tooth growth and repair. Dental tissues, specifically the dental pulp and the dental bud, constitute a relevant source of multipotent stem cells, known as dental-derived stem cells (d-DSCs): dental pulp stem cells (DPSCs) and dental bud stem cells (DBSCs). Cell treatment with bone-associated factors and stimulation with small molecule compounds are, among the available methods, the ones who show excellent advantages promoting stem cell differentiation and osteogenesis. Recently, attention has been paid to studies on natural and non-natural compounds. Many fruits, vegetables, and some drugs contain molecules that can enhance MSC osteogenic differentiation and therefore bone formation. The purpose of this review is to examine research work over the past 10 years that has investigated two different types of MSCs from dental tissues that are attractive targets for bone tissue engineering: DPSCs and DBSCs. The reconstruction of bone defects, in fact, is still a challenge and therefore more research is needed; the articles reviewed are meant to identify compounds useful to stimulate d-DSC proliferation and osteogenic differentiation. We only consider the results of the research which is encouraging, assuming that the mentioned compounds are of some importance for bone regeneration.

Role of Mesenchymal Stem Cells and Short Chain Fatty Acids in Allergy: A Prophylactic Therapy for Future

Allergic diseases are broadly classified as IgE-mediated type-I hypersensitivity immune reactions due to exposure to typically harmless substances known as allergens. These allergenic substances activate antigen presenting cells, which further triggers T-helper 2 cells immune response and class switch B-cells for synthesis of allergen-specific IgE, followed by classical activation of inflammatory mast cells and eosinophils, which releases preformed mediators involved in the cascade of allergic symptoms. However, the role of Mesenchymal stem cells (MSCs) in tissue repair ability and immunomodulation, makes them as an appropriate tool for treatment of various allergic diseases. Several clinical and preclinical studies show that MSCs could be a promising alternative therapy to allergic diseases. Further, short chain fatty acids, produced from gut microbes by breaking down complex fibre-rich foods, acts through G-coupled receptor mediated activation of MSCs, and their role as key players involved in amelioration of allergic inflammation needs further investigation. Therefore, there is a need for understating the role of SCFAs on the activation of MSCs, which might shed light on the development of new therapeutic regime in allergy treatment. In summary, this review focuses on the underlying of therapeutic role of MSCs in different allergic diseases and the prospects of SCFA and MSC therapy.

The Self Assembling peptide P11-4 influences viability and osteogenic differentiation of stem cells of the apical papilla (SCAP)

OBJECTIVE

to analyze the effect of P₁₁-4 self-assembly peptide on cell viability and osteogenic capacity of SCAPs through mineral deposition and gene expression of osteogenic markers. .

METHODS

SCAPs were seeded in contact with P₁₁-4 (10 µg/ml, 100 µg/ml and 1 mg/ml) solution. Cell viability was evaluated using a colorimetric assay MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) in an experimental time of 24, 48 and 72 h (n=7). Mineral deposition and quantification provided by the cells was tested using the Alizarin Red staining and Cetylpyridinium Chloride (CPC), respectively, after 30 days (n=4). Gene expression of Runt-related transcription factor 2 (RUNX2), Alkaline phosphatase (ALP) and Osteocalcin (OCN) was quantified using quantitative polymerase chain reaction (RT-qPCR), at 3 and 7 days with Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as the housekeeping gene, and relative gene expression was measured using the ΔΔCq method. Data were analyzed using Kruskall-Wallis followed by multiple comparisons, and T-test for gene expression with α=0.05.

RESULTS

All tested concentrations (10 µg/ml, 100 µg/ml and 1 mg/ml) were not cytotoxic at time 24 and 48 h. After 72 h, a slight decrease in cell viability was observed for the lowest concentration (10 µg/ml). The concentration of 100 µg/ml P11-4 showed the highest mineral deposition. However, qPCR analysis of P11-4 (10 µg/ml) showed upregulation of RUNX2 and OCN at 3 days, with downregulation of ALP at 3 and 7d.

CONCLUSION

P11-4 did not affect cell viability, induced mineral deposition in SCAPs, and upregulated the expression of RUNX2 and OCN genes at 3 days, while downregulating ALP expression at 3 and 7 days.

CLINICAL SIGNIFICANCE

Based on the results obtained in this study it can be stated that self-assembling peptide P11-4 is a potential candidate to induce mineralization on dental stem cells for regenerative purposes and also for a clinical use as a capping agent without compromising the cells health.

Three-dimensional spheroid culture of dental pulp-derived stromal cells enhance their biological and regenerative properties for potential therapeutic applications

Mesenchymal stem/stromal cell (MSC) spheroids generated in a three-dimensional (3D) culture system serve as a surrogate model that maintain stem cell characteristics since these mimic the in vivo behavior of cells and tissue more closely. Our study involved a detailed characterization of the spheroids generated in ultra-low attachment flasks. The spheroids were evaluated and compared for their morphology, structural integrity, viability, proliferation, biocomponents, stem cell phenotype and differentiation abilities with monolayer culture derived cells (2D culture). The in-vivo therapeutic efficacy of DPSCs derived from 2D and 3D culture was also assessed by transplanting them in an animal model of the critical-sized calvarial defect. DPSCs formed compact and well-organized multicellular spheroids when cultured in ultra-low attachment condition with superior stemness, differentiation, and regenerative abilities than monolayer cells. They maintained lower proliferative state and showed marked difference in the cellular biocomponents such as lipid, amide and nucleic acid between DPSCs from 2D and 3D cultures. The scaffold-free 3D culture efficiently preserves DPSCs intrinsic properties and functionality by maintaining them in the state close to the native tissues. The scaffold free 3D culture methods allow easy collection of a large number of multicellular spheroids of DPSCs and therefore, this can be adopted as a feasible and efficient method of generating robust spheroids for various in-vitro and in-vivo therapeutic applications.

Evaluation of Direct and Indirect Pulp Capping With Biodentine in Vital Permanent Teeth With Deep Caries Lesions

INTRODUCTION

Pulp capping is a procedural method of preserving pulp vitality following deep caries damage or accidental pulp exposure. Biodentine is a calcium silicate material that has been promoted for use in pulp capping among various clinical applications. This study evaluated the outcome of pulp capping with Biodentine following curettage of deep caries in the case series of permanent mature teeth.

MATERIALS AND METHODS

The study was carried out on 40 teeth with advanced caries treated by direct and indirect pulp capping using Biodentine, within a follow-up of six months. This was carried out at the Department of Conservative Dentistry-Endodontics of the CCTD Ibn Rochd-Casablanca.  Results: In this study, 43 teeth from 37 patients were treated with direct pulp capping and indirect pulp capping using Biodentine. The success rate of pulp capping was 90% at one month, 85% at three months, and 80% at six months.

CONCLUSION

The results of the studies conducted using Biodentine indicate that it is a suitable material for direct and indirect pulp capping, due to its bioactivity and ability to form a dentinal bridge.

Immunomodulatory Mechanism and Potential Application of Dental Pulp-Derived Stem Cells in Immune-Mediated Diseases

Dental pulp stem cells (DPSCs) are mesenchymal stem cells (MSCs) derived from dental pulp tissue, which have high self-renewal ability and multi-lineage differentiation potential. With the discovery of the immunoregulatory ability of stem cells, DPSCs have attracted much attention because they have similar or even better immunomodulatory effects than MSCs from other sources. DPSCs and their exosomes can exert an immunomodulatory ability by acting on target immune cells to regulate cytokines. DPSCs can also migrate to the lesion site to differentiate into target cells to repair the injured tissue, and play an important role in tissue regeneration. The aim of this review is to summarize the molecular mechanism and target cells of the immunomodulatory effects of DPSCs, and the latest advances in preclinical research in the treatment of various immune-mediated diseases, providing new reflections for their clinical application. DPSCs may be a promising source of stem cells for the treatment of immune-mediated diseases.

Human dental pulp stem cell monolayer and spheroid therapy after spinal motor root avulsion in adult rats

Spinal cord injuries result in severe neurological deficits and neuronal loss, with poor functional recovery. Mesenchymal stem cells have shown promising results; therefore the present objective of this work was to compare motor recovery after treatment with human dental pulp stem cells (hDPSC) cultivated in monolayer (2D) or as spheroids (3D), following avulsion and reimplantation of spinal motor roots in adult rats. Thus, 72 adult female Lewis rats were divided into 4 groups: avulsion (AV); avulsion followed by reimplantation (AR); avulsion associated with reimplant and 2D cell therapy (AR + 2D), and avulsion associated with reimplant and 3D cell therapy (AR + 3D). The application of the cells in 2D and 3D was performed by microsurgery, with subsequent functional assessment using a walking track test (Catwalk system), immunohistochemistry, neuronal survival, and qRT-PCR in 1-, 4-, and 12-weeks post-injury. The animals in the AR + 2D and AR + 3D groups showed the highest neuronal survival rates, and immunofluorescence revealed downregulation of GFAP, and Iba-1, with preservation of synaptophysin, indicating a reduction in glial reactivity, combined with the maintenance of pre-synaptic inputs. There was an increase in anti-inflammatory (IL-4, TGFβ) and a reduction of pro-inflammatory factors (IL-6, TNFα) in animals treated with reimplantation and hDPSC. As for the functional recovery, in all analyzed parameters, the AR + 2D group performed better and was superior to the avulsion alone. Overall, our results indicate that the 2D and 3D cell therapy approaches provide successful immunomodulation and motor recovery, consistent with advanced therapies after spinal cord injury.

Human Bone Marrow-Derived Mesenchymal Stromal Cells Reduce the Severity of Experimental Necrotizing Enterocolitis in a Concentration-Dependent Manner

Necrotizing enterocolitis (NEC) is a devastating gut disease in preterm neonates. In NEC animal models, mesenchymal stromal cells (MSCs) administration has reduced the incidence and severity of NEC. We developed and characterized a novel mouse model of NEC to evaluate the effect of human bone marrow-derived MSCs (hBM-MSCs) in tissue regeneration and epithelial gut repair. NEC was induced in C57BL/6 mouse pups at postnatal days (PND) 3-6 by (A) gavage feeding term infant formula, (B) hypoxia/hypothermia, and (C) lipopolysaccharide. Intraperitoneal injections of PBS or two hBM-MSCs doses (0.5 × 10⁶ or 1 × 10⁶) were given on PND2. At PND 6, we harvested intestine samples from all groups. The NEC group showed an incidence of NEC of 50% compared with controls (p < 0.001). Severity of bowel damage was reduced by hBM-MSCs compared to the PBS-treated NEC group in a concentration-dependent manner, with hBM-MSCs (1 × 10⁶) inducing a NEC incidence reduction of up to 0% (p < 0.001). We showed that hBM-MSCs enhanced intestinal cell survival, preserving intestinal barrier integrity and decreasing mucosal inflammation and apoptosis. In conclusion, we established a novel NEC animal model and demonstrated that hBM-MSCs administration reduced the NEC incidence and severity in a concentration-dependent manner, enhancing intestinal barrier integrity.

Hopes and opportunities of stem cells from human exfoliated deciduous teeth (SHED) in cartilage tissue regeneration

Cartilage lesions are common conditions, affecting elderly and non-athletic populations. Despite recent advances, cartilage regeneration remains a major challenge today. The absence of an inflammatory response following damage and the inability of stem cells to penetrate into the healing site due to the absence of blood and lymph vessels are assumed to hinder joint repair. Stem cell-based regeneration and tissue engineering have opened new horizons for treatment. With advances in biological sciences, especially stem cell research, the function of various growth factors in the regulation of cell proliferation and differentiation has been established. Mesenchymal stem cells (MSCs) isolated from different tissues have been shown to increase into therapeutically relevant cell numbers and differentiate into mature chondrocytes. As MSCs can differentiate and become engrafted inside the host, they are considered suitable candidates for cartilage regeneration. Stem cells from human exfoliated deciduous teeth (SHED) provide a novel and non-invasive source of MSCs. Due to their simple isolation, chondrogenic differentiation potential, and minimal immunogenicity, they can be an interesting option for cartilage regeneration. Recent studies have reported that SHED-derived secretome contains biomolecules and compounds that efficiently promote regeneration in damaged tissues, including cartilage. Overall, this review highlighted the advances and challenges of cartilage regeneration using stem cell-based therapies by focusing on SHED.

The Wisdom in Teeth: Neuronal Differentiation of Dental Pulp Cells

Mesenchymal stem/stromal cells (MSCs) are found in almost all postnatal organs. Under appropriate environmental cues, multipotency enables MSCs to serve as progenitors for several lineage-specific, differentiated cell types. In vitro expansion and differentiation of MSCs give the opportunity to obtain hardly available somatic cells, such as neurons. The neurogenic potential of MSCs makes them a promising, autologous source to restore damaged tissue and as such, they have received much attention in the field of regenerative medicine. Several stem cell pool candidates have been studied thus far, but only a few of them showed neurogenic differentiation potential. Due to their embryonic ontology, stem cells residing in the stroma of the dental pulp chamber are an exciting source for in vitro neural cell differentiation. In this study, we review the key properties of dental pulp stem cells (DPSCs), with a particular focus on their neurogenic potential. Moreover, we summarize the various presently available methods used for neural differentiation of human DPSCs also emphasizing the difficulties in reproducibly high production of such cells. We postulate that because DPSCs are stem cells with very close ontology to neurogenic lineages, they may serve as excellent targets for neuronal differentiation in vitro and even for direct reprogramming.

The potential roles of dental pulp stem cells in peripheral nerve regeneration

Peripheral nerve diseases are significantly correlated with severe fractures or trauma and surgeries, leading to poor life quality and impairment of physical and mental health. Human dental pulp stem cells (DPSCs) are neural crest stem cells with a strong multi-directional differentiation potential and proliferation capacity that provide a novel cell source for nerve regeneration. DPSCs are easily extracted from dental pulp tissue of human permanent or deciduous teeth. DPSCs can express neurotrophic and immunomodulatory factors and, subsequently, induce blood vessel formation and nerve regeneration. Therefore, DPSCs yield valuable therapeutic potential in the management of peripheral neuropathies. With the purpose of summarizing the advances in DPSCs and their potential applications in peripheral neuropathies, this article reviews the biological characteristics of DPSCs in association with the mechanisms of peripheral nerve regeneration.

C5L2 modulates BDNF production in human dental pulp stem cells via p38α pathway

Tissue injury affects nerve fibers and triggers an immune response, leading to inflammation. The complement system gets activated during inflammatory conditions and has been reported to be involved in the regeneration process. We have demonstrated that the C5a receptor (C5aR) has crucial roles in regeneration and healing processes including nerve sprouting and hard tissue formation. Another C5a-like 2 receptor (C5AR2; C5L2) has been cloned which is still considered controversial due to limited studies. We previously established that C5L2 regulates brain-derived neurotrophic factor (BDNF) secretion in pulp fibroblasts. However, there is no study available on human dental pulp stem cells (DPSCs), especially in the inflammatory context. Stem cell therapy is an emerging technique to treat and prevent several diseases. DPSCs are a great option to be considered due to their great ability to differentiate into a variety of cells and secrete nerve regeneration factors. Here, we demonstrated that C5L2 modulates BDNF secretion in DPSCs. Our results stated that C5L2 silencing through siRNA could increase BDNF production, which could accelerate the nerve regeneration process. Moreover, stimulation with lipopolysaccharide (LPS) enhanced BDNF production in C5L2 silenced DPSCs. Finally, we quantified BDNF secretion in supernatant and cell lysates using ELISA. Our results showed enhanced BDNF production in C5L2 silenced DPSCs and hampered by the p38MAPKα inhibitor. Taken together, our data reveal that C5L2 modulates BDNF production in DPSCs via the p38MAPKα pathway.

Metabolic shift and the effect of mitochondrial respiration on the osteogenic differentiation of dental pulp stem cells

Background

Metabolism shifts from glycolysis to mitochondrial oxidative phosphorylation are vital during the differentiation of stem cells. Mitochondria have a direct function in differentiation. However, the metabolic shift and the effect of mitochondria in regulating the osteogenic differentiation of human dental pulp stem cells (hDPSCs) remain unclear.

Methods

Human dental pulp stem cells were collected from five healthy donors. Osteogenic differentiation was induced by osteogenic induction medium. The activities of alkaline phosphatase, hexokinase, pyruvate kinase, and lactate dehydrogenase were analyzed by enzymatic activity kits. The extracellular acidification rate and the mitochondrial oxygen consumption rate were measured. The mRNA levels of COL-1, ALP, TFAM, and NRF1 were analyzed. The protein levels of p-AMPK and AMPK were detected by western blotting.

Results

Glycolysis decreased after a slight increase, while mitochondrial oxidative phosphorylation continued to increase when cells grew in osteogenic induction medium. Therefore, the metabolism of differentiating cells switched to mitochondrial respiration. Next, inhibiting mitochondrial respiration with carbonyl cyanide-chlorophenylhydrazone, a mitochondrial uncoupler inhibited hDPSCs differentiation with less ALP activity and decreased ALP and COL-1 mRNA expression. Furthermore, mitochondrial uncoupling led to AMPK activation. 5-Aminoimidazole-4-carboxamide ribonucleotide, an AMPK activator, simulated the effect of mitochondrial uncoupling by inhibiting osteogenic differentiation, mitochondrial biogenesis, and mitochondrial morphology. Mitochondrial uncoupling and activation of AMPK depressed mitochondrial oxidative phosphorylation and inhibited differentiation, suggesting that they may serve as regulators to halt osteogenic differentiation from impaired mitochondrial oxidative phosphorylation.

Biomineralization-inspired sandwich dentin desensitization strategy based on multifunctional nanocomposite with yolk-shell structure

Dentin hypersensitivity (DH) treatment is far from being unequivocal in providing a superior strategy that combines immediate and long-term efficiency of dentinal tubule (DT) occlusion and clinical applicability. In order to achieve this aim, a type of multifunctional yolk-shell nanocomposite with acid resistance, mechanical resistance and biomineralization properties was developed in this study, which consists of a silica/mesoporous titanium-zirconium nanocarrier (STZ) and poly(allylamine hydrochloride) (PAH)-stabilized amorphous calcium phosphate (ACP) liquid precursor. First, the nanocomposite, named as PSTZ, immediately occluded DTs and demonstrated outstanding acid and mechanical resistance. Second, the PSTZ nanocomposite induced intrafibrillar mineralization of single-layer collagen fibrils and remineralization of demineralized dentin matrix. Finally, PSTZ promoted the odontogenic differentiation of dental pulp stem cells by releasing ACP and silicon ions. The reconstruction of the dentin-mimicking hierarchical structure and the introduction of newly formed minerals in the upper, middle and lower segments of DTs, defined as sandwich-like structures, markedly reduced the permeability and achieved superior long-term sealing effects. The nanocomposite material based on mesoporous yolk-shell carriers and liquid-phase mineralized precursors developed in this study represents a versatile biomimetic sandwich desensitization strategy and offers fresh insight into the clinical management of DH.

Towards a New Concept of Regenerative Endodontics Based on Mesenchymal Stem Cell-Derived Secretomes Products

The teeth, made up of hard and soft tissues, represent complex functioning structures of the oral cavity, which are frequently affected by processes that cause structural damage that can lead to their loss. Currently, replacement therapy such as endodontics or implants, restore structural defects but do not perform any biological function, such as restoring blood and nerve supplies. In the search for alternatives to regenerate the dental pulp, two alternative regenerative endodontic procedures (REP) have been proposed: (I) cell-free REP (based in revascularization and homing induction to remaining dental pulp stem cells (DPSC) and even stem cells from apical papilla (SCAP) and (II) cell-based REP (with exogenous cell transplantation). Regarding the last topic, we show several limitations with these procedures and therefore, we propose a novel regenerative approach in order to revitalize the pulp and thus restore homeostatic functions to the dentin-pulp complex. Due to their multifactorial biological effects, the use of mesenchymal stem cells (MSC)-derived secretome from non-dental sources could be considered as inducers of DPSC and SCAP to completely regenerate the dental pulp. In partial pulp damage, appropriate stimulate DPSC by MSC-derived secretome could contribute to formation and also to restore the vasculature and nerves of the dental pulp.

Dose-Dependent Effects of Melatonin on the Viability, Proliferation, and Differentiation of Dental Pulp Stem Cells (DPSCs)

(1) Background: Dental pulp stem cells (DPSCs) are derived from pulp tissue lodged within human teeth and are mesenchymal in origin. These DPSCs have been demonstrated to dissociate into clusters of various cell lineages and are very easy to isolate, culture, and expand. Melatonin, a multifaceted molecule with a spectrum of effects in the human body, is known to influence stem cell viability, proliferation, and differentiation, but little is known about the impact melatonin has on the capacity of DPSCs to differentiate into adipocytes, osteocytes, and chondrocytes. The primary objective of this research was to explore the impact that melatonin has on proliferation, and the capacity of DPSCs to differentiate into adipocytes, osteocytes, and chondrocytes. (2) Methodology: DPSCs were extracted from 12 healthy human teeth, cultured, and expanded. Flow cytometry was performed to examine the surface stem cell markers. Further, melatonin was added to the cultured DPSCs in various concentrations, to assess cytotoxicity using an MTT assay. Following this, the DPSCs were tested for their proliferative ability, as well as adipogenic, osteogenic, and chondrogenic differentiation capabilities under the influence of variable concentrations of melatonin. (3) Results: DPSCs obtained from human teeth demonstrated surface characteristics of mesenchymal stem cells, as shown by the positive expression of CD105, CD90, and CD73 markers. An MTT cytotoxicity assay revealed that melatonin was well tolerated by the cells at low (1 µM) and high (25 µM) concentrations. Assessment of DPSC cell differentiation elucidated that melatonin at 1 µM and 25 µM concentrations with the induction media stimulated DPSCs to differentiate into osteocytes, but did not have much influence on adipogenic and chondrogenic differentiation. (4) Conclusions: Melatonin could be used in stem cell and tissue engineering applications for osteogenic differentiation of DPSCs and could protect these cells due to its cytoprotective, immunomodulatory, and antioxidant roles, in addition to being an osteopromoter molecule.

Osteogenic enhancement of modular ceramic nanocomposites impregnated with human dental pulp stem cells: an approach for bone repair and regenerative medicine

Background/aim

Human dental pulp-derived mesenchymal stem cells (hDP-MSCs) are a promising source of progenitor cells for bone tissue engineering. Nanocomposites made of calcium phosphate especially hydroxyapatite (HA) offer an impressive solution for orthopedic and dental implants. The combination of hDP-MSCs and ceramic nanocomposites has a promising therapeutic potential in regenerative medicine. Despite the calcium phosphate hydroxyapatite (HA)-based nanocomposites offer a good solution for orthopedic and dental implants, the heavy load-bearing clinical applications require higher mechanical strength, which is not of the HA’ properties that have low mechanical strength. Herein, the outcomes of using fabricated ceramic nanocomposites of hydroxyapatite/titania/calcium silicate mixed at different ratios (C1, C2, and C3) and impregnated with hDP-MSCs both in in vitro cultures and rabbit model of induced tibial bone defect were investigated. Our aim is to find out a new approach that would largely enhance the osteogenic differentiation of hDP-MSCs and has a therapeutic potential in bone regeneration.

Subjects and methods

Human DP-MSCs were isolated from the dental pulp of the third molar and cultured in vitro. Alizarin Red staining was performed at different time points to assess the osteogenic differentiation. Flow cytometer was used to quantify the expression of hDP-MSCs unique surface markers. Rabbits were used as animal models to evaluate the therapeutic potential of osteogenically differentiated hDP-MSCs impregnated with ceramic nanocomposites of hydroxyapatite/tatiana/calcium silicate (C1, C2, and C3). Histopathological examination and scanning electron microscopy (SEM) were performed to evaluate bone healing potential in the rabbit induced tibial defects three weeks post-transplantation.

Results

The hDP-MSCs showed high proliferative and osteogenic potential in vitro culture. Their osteogenic differentiation was accelerated by the ceramic nanocomposites’ scaffold and revealed bone defect’s healing in transplanted rabbit groups compared to control groups. Histopathological and SEM analysis of the transplanted hDP-MSCs/ceramic nanocomposites showed the formation of new bone filling in the defect area 3 weeks post-implantation. Accelerate osseointegration and enhancement of the bone-bonding ability of the prepared nanocomposites were also confirmed by SEM.

Conclusions

The results strongly suggested that ceramic nanocomposites of hydroxyapatite/ titania /calcium silicate (C1, C2, and C3) associated with hDP-MSCs have a therapeutic potential in bone healing in a rabbit model. Hence, the combined osteogenic system presented here is recommended for application in bone tissue engineering and regenerative medicine.

An optimized method for obtaining clinical-grade specific cell subpopulations from human umbilical cord-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are heterogeneous populations with broad application prospects in cell therapy, and using specific subpopulations of MSCs can enhance their particular capability under certain conditions and achieve better therapeutic effects. However, no studies have reported how to obtain high‐quality specific MSC subpopulations in vitro culture. Here, for the first time, we established a general operation process for obtaining high‐quality clinical‐grade cell subpopulations from human umbilical cord MSCs (hUC‐MSCs) based on particular markers. We used the MSC‐CD106⁺ subpopulations, whose biological function has been well documented, as an example to explore and optimize the crucial links of primary preparation, pre‐treatment, antibody incubation, flow sorting, quality and function test. After comprehensively evaluating the quality and function of the acquired MSC‐CD106⁺ subpopulations, including in vitro cell viability, apoptosis, proliferation, marker stability, adhesion ability, migration ability, tubule formation ability, immunomodulatory function and in vivo wound healing ability and proangiogenic activity, we defined an important pre‐treatment scheme which might effectively improve the therapeutic efficiency of MSC‐CD106⁺ subpopulations in two critical clinical application scenarios—direct injection after cell sorting and post‐culture injection into bodies. Based on the above, we tried to establish a general five‐step operation procedure for acquiring high‐quality clinical‐grade MSC subpopulations based on specific markers, which cannot only improve their enrichment efficiency and the reliability of preclinical studies, but also provide valuable methodological guidance for the rapid clinical transformation of specific MSC subpopulations.

Dopamine‐related oxidative stress and mitochondrial dysfunction in dopaminergic neurons differentiated from deciduous teeth‐derived stem cells of children with Down syndrome

Down syndrome (DS) is one of the common genetic disorders caused by the trisomy of human chromosome 21 (HSA21). Mitochondrial dysfunction and redox imbalance play important roles in DS pathology, and altered dopaminergic regulation has been demonstrated in the brain of individuals with DS. However, the pathological association of these elements is not yet fully understood. In this study, we analyzed dopaminergic neurons (DNs) differentiated from deciduous teeth‐derived stem cells of children with DS or healthy control children. As previously observed in the analysis of a single case of DS, compared to controls, patient‐derived DNs (DS‐DNs) displayed shorter neurite outgrowth and fewer branches, as well as downregulated vesicular monoamine transporter 2 and upregulated dopamine transporter 1, both of which are key regulators of dopamine homeostasis in DNs. In agreement with these expression profiles, DS‐DNs accumulated dopamine intracellularly and had increased levels of cellular and mitochondrial reactive oxygen species (ROS). DS‐DNs showed downregulation of non‐canonical Notch ligand, delta‐like 1, which may contribute to dopamine accumulation and increased ROS levels through DAT1 upregulation. Furthermore, DS‐DNs showed mitochondrial dysfunction in consistent with lower expression of peroxisome proliferator‐activated receptor‐gamma coactivator 1 alpha (PGC‐1α) and upregulation of a HSA21‐encoded negative regulator of PGC‐1α, nuclear receptor‐interacting protein 1. These results suggest that dysregulated dopamine homeostasis may participate in oxidative stress and mitochondrial dysfunction of the dopaminergic system in DS.

Lineage Differentiation Potential of Different Sources of Mesenchymal Stem Cells for Osteoarthritis Knee

Tissue engineering and regenerative medicine (TERM) have paved a way for treating musculoskeletal diseases in a minimally invasive manner. The regenerative medicine cocktail involves the usage of mesenchymal stem/stromal cells (MSCs), either uncultured or culture-expanded cells along with growth factors, cytokines, exosomes, and secretomes to provide a better regenerative milieu in degenerative diseases. The successful regeneration of cartilage depends on the selection of the appropriate source of MSCs, the quality, quantity, and frequency of MSCs to be injected, and the selection of the patient at an appropriate stage of the disease. However, confirmation on the most favorable source of MSCs remains uncertain to clinicians. The lack of knowledge in the current cellular treatment is uncertain in terms of how beneficial MSCs are in the long-term or short-term (resolution of pain) and improved quality of life. Whether MSCs treatments have any superiority, exists due to sources of MSCs utilized in their potential to objectively regenerate the cartilage at the target area. Many questions on source and condition remain unanswered. Hence, in this review, we discuss the lineage differentiation potentials of various sources of MSCs used in the management of knee osteoarthritis and emphasize the role of tissue engineering in cartilage regeneration.

Complement C5aR/LPS-induced BDNF and NGF modulation in human dental pulp stem cells

Stem cells with the ability to differentiate into a variety of cells and secrete nerve regeneration factors have become an emerging option in nerve regeneration. Dental pulp stem cells (DPSCs) appear to be a good candidate for nerve regeneration given their accessibility, neural crest origin, and neural repair qualities. We have recently demonstrated that the complement C5a system, which is an important mediator of inflammation and tissue regeneration, is activated by lipoteichoic acid-treated pulp fibroblasts, and governs the production of brain-derived nerve growth factor (BDNF). This BDNF secretion promotes neurite outgrowth towards the injury site. Here, we extend our observation to DPSCs and compare their neurogenic ability to bone marrow-derived mesenchymal stem cells (BM-MSCs) under inflammatory stimulation. Our ELISA and immunostaining data demonstrate that blocking the C5a receptor (C5aR) reduced BDNF production in DPSCs, while treatment with C5aR agonist increased the BDNF expression, which suggests that C5aR has a positive regulatory role in the BDNF modulation of DPSCs. Inflammation induced by lipopolysaccharide (LPS) treatment potentiated this effect and is C5aR dependent. Most important, DPSCs produced significantly higher levels of C5aR-mediated BDNF compared to BM-MSCs. Taken together, our data reveal novel roles for C5aR and inflammation in modulation of BDNF and NGF in DPSCs.

Angiogenesis during coronal pulp regeneration using rat dental pulp cells: Neovascularization in rat molars in vivo and proangiogenic dental pulp cell-endothelial cell interactions in vitro

Background/purpose

Angiogenesis is considered a crucial event for dental pulp regeneration. The purpose of this study was to demonstrate neovascularization during coronal pulp regeneration in rat molars using rat dental pulp cells (rDPCs) and to examine whether rDPC-endothelial cell interactions promote proangiogenic capacity in vitro.

Materials and methods

Maxillary first molars of Wistar rats (n = 42) were pulpotomized and rDPCs isolated from incisors were implanted with a porous poly (l-lactic acid) (PLLA) scaffold and hydrogel (Matrigel). After 3, 7, and 14 days, coronal pulp tissues were examined histologically and by nestin and CD146 immunohistochemistry. rDPCs and rat dermal microvascular endothelial cells (rDMECs) were cocultured for 4 days and vascular endothelial growth factor (VEGF) synthesis and angiogenic factor gene expression were determined by enzyme-linked immunosorbent assays and real-time polymerase chain reaction, respectively. Effects of cocultured medium on tube formation by rDMECs were also evaluated.

Results

Implantation of rDPC/PLLA/Matrigel induced coronal pulp regeneration with dentin bridge formation and arrangement of nestin-positive odontoblast-like cells at 14 days. PLLA/Matrigel without rDPCs did not induce pulp regeneration. CD146-positive blood vessels increased in density in the remaining pulp tissues at 3 and 7 days, and in the regenerated pulp tissue at 14 days. rDPC/DMEC coculture significantly promoted VEGF secretion and mRNA expression of nuclear factor-kappa B, angiogenic chemokine CXCL1, and chemokine receptor CXCR1. Cocultured medium significantly promoted tube formation.

Conclusion

Coronal pulp regeneration with rDPC/PLLA/Matrigel was accompanied by neovascularization. rDPC-rDMEC interactions may promote angiogenic activity represented by proangiogenic factor upregulation and tube formation in vitro.

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.

General gene expression patterns and stemness of the gingiva and dental pulp

Background/purpose

Due to the unique properties of healing processes and cellular differentiation, the gingiva and dental pulp have attracted attention as a potential source of mesenchymal stem cells (MSCs). The purpose of this study was to obtain molecular-level information on these tissues in terms of their function and differentiation processes and investigate stemness.

Materials and methods

Healthy gingival tissues were collected from patients (n = 9; aged 7–12 years) who underwent simple surgical procedures, and normal dental pulp tissues were obtained from patients (n = 25; aged 11–25 years) undergoing tooth extraction for orthodontic reasons. Complementary DNA microarray, qRT-qPCR, and immunohistochemical staining were performed to assess general and MSC gene expression patterns.

Results

In the gingival tissue, genes related to keratinization, the formation of epithelial cells and ectoderm, and immune and/or inflammatory responses were highly expressed. Meanwhile, in the dental pulp tissue, genes related to ion transport, neuronal development and axon guidance, bone and enamel mineralization, extracellular matrix organization, and angiogenesis were highly expressed. When focusing on the expression of MSC genes, induced pluripotent stem (iPS) cell genes, such as Sox2, c-Myc, and KLF4, were expressed at higher levels in the gingival tissue, whereas dental stem cell genes, such as NT5E and VCAM1, were expressed in dental pulp tissue.

Conclusion

We found different general and MSC gene expression patterns between the gingival and dental pulp tissue. These results have implications for future regenerative medicine, considering the application of gingival tissue as a potential source of iPS cells.

Epigenetic regulation of dental pulp stem cells and its potential in regenerative endodontics

Regenerative endodontics (RE) therapy means physiologically replacing damaged pulp tissue and regaining functional dentin–pulp complex. Current clinical RE procedures recruit endogenous stem cells from the apical papilla, periodontal tissue, bone marrow and peripheral blood, with or without application of scaffolds and growth factors in the root canal space, resulting in cementum-like and bone-like tissue formation. Without the involvement of dental pulp stem cells (DPSCs), it is unlikely that functional pulp regeneration can be achieved, even though acceptable repair can be acquired. DPSCs, due to their specific odontogenic potential, high proliferation, neurovascular property, and easy accessibility, are considered as the most eligible cell source for dentin–pulp regeneration. The regenerative potential of DPSCs has been demonstrated by recent clinical progress. DPSC transplantation following pulpectomy has successfully reconstructed neurovascularized pulp that simulates the physiological structure of natural pulp. The self-renewal, proliferation, and odontogenic differentiation of DPSCs are under the control of a cascade of transcription factors. Over recent decades, epigenetic modulations implicating histone modifications, DNA methylation, and noncoding (nc)RNAs have manifested as a new layer of gene regulation. These modulations exhibit a profound effect on the cellular activities of DPSCs. In this review, we offer an overview about epigenetic regulation of the fate of DPSCs; in particular, on the proliferation, odontogenic differentiation, angiogenesis, and neurogenesis. We emphasize recent discoveries of epigenetic molecules that can alter DPSC status and promote pulp regeneration through manipulation over epigenetic profiles.

Novel Bioactive Adhesive Monomer CMET Promotes Odontogenic Differentiation and Dentin Regeneration

This study aimed to evaluate the in vitro effect of the novel bioactive adhesive monomer CMET, a calcium salt of 4-methacryloxyethyl trimellitate acid (4-MET), on human dental pulp stem cells (hDPSCs) and its capacity to induce tertiary dentin formation in a rat pulp injury model. Aqueous solutions of four tested materials [4-MET, CMET, Ca(OH)₂, and mineral trioxide aggregate (MTA)] were added to the culture medium upon confluence, and solvent (dH₂O) was used as a control. Cell proliferation was assessed using the Cell Counting Kit-8 assay, and cell differentiation was evaluated by real-time quantitative reverse transcription-polymerase chain reaction. The mineralization-inducing capacity was evaluated using alizarin red S staining and an alkaline phosphatase activity assay. For an in vivo experiment, a mechanical pulp exposure model was prepared on Wistar rats; damaged pulp was capped with Ca(OH)₂ or CMET. Cavities were sealed with composite resin, and specimens were assessed after 14 and 28 days. The in vitro results showed that CMET exhibited the lowest cytotoxicity and highest odontogenic differentiation capacity among all tested materials. The favorable outcome on cell mineralization after treatment with CMET involved p38 and c-Jun N-terminal kinases signaling. The nuclear factor kappa B pathway was involved in the CMET-induced mRNA expression of odontogenic markers. Similar to Ca(OH)₂, CMET produced a continuous hard tissue bridge at the pulp exposure site, but treatment with only CMET produced a regular dentinal tubule pattern. The findings suggest that (1) the evaluated novel bioactive adhesive monomer provides favorable biocompatibility and odontogenic induction capacity and that (2) CMET might be a very promising adjunctive for pulp-capping materials.

Identification of stemness and differentially expressed genes in human cementum-derived cells

Purpose

Periodontal treatment aims at complete regeneration of the periodontium, and developing strategies for periodontal regeneration requires a deep understanding of the tissues composing the periodontium. In the present study, the stemness characteristics and gene expression profiles of cementum-derived cells (CDCs) were investigated and compared with previously established human stem cells. Candidate marker proteins for CDCs were also explored.

Methods

Periodontal ligament stem cells (PDLSCs), pulp stem cells (PULPSCs), and CDCs were isolated and cultured from extracted human mandibular third molars. Human bone marrow stem cells (BMSCs) were used as a positive control. To identify the stemness of CDCs, cell differentiation (osteogenic, adipogenic, and chondrogenic) and surface antigens were evaluated through flow cytometry. The expression of cementum protein 1 (CEMP1) and cementum attachment protein (CAP) was investigated to explore marker proteins for CDCs through reverse-transcription polymerase chain reaction. To compare the gene expression profiles of the 4 cell types, mRNA and miRNA microarray analysis of 10 samples of BMSCs (n=1), PDLSCs (n=3), PULPSCs (n=3), and CDCs (n=3) were performed.

Results

The expression of mesenchymal stem cell markers with a concomitant absence of hematopoietic markers was observed in PDLSCs, PULPSCs, CDCs and BMSCs. All 4 cell populations also showed differentiation into osteogenic, adipogenic, and chondrogenic lineages. CEMP1 was strongly expressed in CDCs, while it was weakly detected in the other 3 cell populations. Meanwhile, CAP was not found in any of the 4 cell populations. The mRNA and miRNA microarray analysis showed that 14 mRNA genes and 4 miRNA genes were differentially expressed in CDCs vs. PDLSCs and PULPSCs.

Conclusions

Within the limitations of the study, CDCs seem to have stemness and preferentially express CEMP1. Moreover, there were several up- or down-regulated genes in CDCs vs. PDLSCs, PULPSCs, and BMSCs and these genes could be candidate marker proteins of CDCs.

Dental Pulp Stem Cells Derived From Adult Human Third Molar Tooth: A Brief Review

The fields of regenerative medicine and stem cell-based tissue engineering have the potential of treating numerous tissue and organ defects. The use of adult stem cells is of particular interest when it comes to dynamic applications in translational medicine. Recently, dental pulp stem cells (DPSCs) have been traced in third molars of adult humans. DPSCs have been isolated and characterized by several groups. DPSCs have promising characteristics including self-renewal capacity, rapid proliferation, colony formation, multi-lineage differentiation, and pluripotent gene expression profile. Nevertheless, genotypic, and phenotypic heterogeneities have been reported for DPSCs subpopulations which may influence their therapeutic potentials. The underlying causes of DPSCs’ heterogeneity remain poorly understood; however, their heterogeneity emerges as a consequence of an interplay between intrinsic and extrinsic cellular factors. The main objective of the manuscript is to review the current literature related to the human DPSCs derived from the third molar, with a focus on their physiological properties, isolation procedures, culture conditions, self-renewal, proliferation, lineage differentiation capacities and their prospective advances use in pre-clinical and clinical applications.

Mapping the Secretome of Dental Pulp Stem Cells Under Variable Microenvironmental Conditions

There is substantial evidence supporting the anti-inflammatory and regenerative potential of dental pulp stem cells (DPSCs) through direct cell transplantation or paracrine action. However, DPSC secretome profile remains inadequately studied. This study provides proteomic profiling of the human DPSC secretome by comparatively analysising cell lysates and respective culture supernatants (i.e. conditioned media-CM) under variable oxygen tension conditions (normoxia-20% O₂/CM_Norm vs. hypoxia 2% O₂/CM_Hyp) and/or stimulation with Tumor Necrosis Factor alpha (TNF-α). DPSC-CM samples and respective crude lysates (DPSC-CL) were collected and subjected to SDS-PAGE, followed by LC-MS/MS analysis. The identified proteins were analyzed by Gene Ontology, Reactome, and String databases. The anti-inflammatory properties of DPSC-CMs were validated via an in vitro RAW_246.7 murine macrophages model through evaluation of the expression of pro-and anti-inflammatory markers by real-time PCR. Results showed a total of 2413 proteins identified in CM_Norm, 2479 in CM_Norm+TNF-α, 1642 in CM_Hyp, and 2002 in CM_Hyp + TNF-α samples. CM_Norm contained 122 proteins statistically significantly upregulated compared to the CM_Hyp and involved in pathways related to "ECM organization", "cellular response to hypoxia", and "IL signaling". Functional network analysis showed that TGFβ1, TIMP1 and TIMP2 were key nodes among proteins significantly upregulated in the CM_Norm compared to the CM_Hyp, interacting with more than 10 proteins, each. DPSC-CM application in the in vitro RAW_246.7 model decreased the expression of pro-inflammatory markers (MMP-3, MMP-9, MMP-13, MCP-1), while increasing anti-inflammatory markers (IL-10). Overall, DPSC-CM collected under normoxic conditions is enriched with anti-inflammatory, tissue repair and regenerative factors, which prompts further investigation on its therapeutic applications.

Chondrogenic Potential of Dental-Derived Mesenchymal Stromal Cells

The field of tissue engineering has revolutionized the world in organ and tissue regeneration. With the robust research among regenerative medicine experts and researchers, the plausibility of regenerating cartilage has come into the limelight. For cartilage tissue engineering, orthopedic surgeons and orthobiologists use the mesenchymal stromal cells (MSCs) of various origins along with the cytokines, growth factors, and scaffolds. The least utilized MSCs are of dental origin, which are the richest sources of stromal and progenitor cells. There is a paradigm shift towards the utilization of dental source MSCs in chondrogenesis and cartilage regeneration. Dental-derived MSCs possess similar phenotypes and genotypes like other sources of MSCs along with specific markers such as dentin matrix acidic phosphoprotein (DMP) -1, dentin sialophosphoprotein (DSPP), alkaline phosphatase (ALP), osteopontin (OPN), bone sialoprotein (BSP), and STRO-1. Concerning chondrogenicity, there is literature with marginal use of dental-derived MSCs. Various studies provide evidence for in-vitro and in-vivo chondrogenesis by dental-derived MSCs. With such evidence, clinical trials must be taken up to support or refute the evidence for regenerating cartilage tissues by dental-derived MSCs. This article highlights the significance of dental-derived MSCs for cartilage tissue regeneration.

Influence of Dental Pulp Harvesting Method on the Viability and Differentiation Capacity of Adult Dental Pulp-Derived Mesenchymal Stem Cells

Objective

To compare two pulp harvesting methods for stem cell expansion, namely, conservative pulpotomy and pulpectomy from exodontia.

Method

Ten freshly extracted sound third molars from five patients were selected. Five were used in the control group, where pulp harvesting was performed by exodontia and the remaining teeth were used in the test group, where the pulp was harvested by conservative pulpotomy (preserving the tooth). This was a split-mouth design study, where a third molar from one side was randomly allocated into the test group and the contralateral tooth in the control group. After pulp harvesting, the following evaluations were performed: cell morphology, sterility test, immunophenotyping, differentiation assays, first pass live cell counts, time to cryopreservation, and total number of expanded cells at the end of the fourth pass.

Results

Regarding morphology, the cells from both groups presented a fibroblastic phenotype. All samples were sterile. Immunophenotyping demonstrated a positive expression for CD105, CD90, and CD73 and negative expression for CD45 in both groups. Differentiation assays were positive for osteogenic and chondrogenic differentiation in both groups. Regarding live cell counts in the first passage, the control group had 95.8% live cells in the total count and the test group 91.2% (p < 0.05). The time required for cryopreservation was equivalent in both groups 51.6 days and 52.6 days, respectively (p > 0.05). The total number of cells at the end of the fourth passage was 5,286,782 and 5,736,862, respectively (p > 0.05).

Conclusion

These results suggest that adult stem cell harvesting from conservative pulpotomy is as effective as the traditional exodontia-based method.

Insensitivity of dental pulp stem cells migration to substrate stiffness

Dental pulp stem cells (DPSCs) are a promising cell source for regeneration of dental pulp. Migration is a key event but influence of the microenvironment rigidity (5 kPa at the center of dental pulp to 20 GPa for the dentin) is largely unknown. Mechanical signals are transmitted from the extracellular matrix to the cytoskeleton, to the nuclei, and to the chromatin, potentially regulating gene expression. To identify the microenvironmental influence on migration, we analyzed motility on PDMS substrates with stiffness increasing from 1.5 kPa up to 2.5 MPa. We found that migration speed slightly increases as substrate stiffness decreases in correlation with decreasing focal adhesion size. Motility is relatively insensitive to substrate stiffness, even on a bi-rigidity PDMS substrate where DPSCs migrate without preferential direction. Migration is independent of both myosin II activity and YAP translocation after myosin II inhibition. Additionally, inhibition of Arp2/3 complex leads to significant speed decrease for all rigidities, suggesting contribution of the lamellipodia in the migration. Interestingly, the chromatin architecture remains stable after a 7-days exposure on the PDMS substrates for all rigidity. To design scaffold mimicking dental pulp environment, similar DPSCs migration for all rigidity, leaves field open to choose this mechanical parameter.

The effect of melatonin on Hippo signaling pathway in dental pulp stem cells

Dental pulp stem cells (DPSCs) have a high capacity to differentiate into the neuronal cell lineage. Meanwhile, both Hippo signaling and melatonin are key regulators in neuronal differentiation of neuronal progenitor cells. Recently emerging evidences suggest the possible interaction between melatonin and Hippo signaling in different cell lines. But underlying mechanisms involved in the initiation or progression of neurogenic differentiation in DPSCs through this connection need to be explored. Therefore, the scope of this study is to investigate the effect of melatonin on Hippo signaling pathway through the expression of its downstream effector (YAP/p-YAP^Y357) after the neuronal differentiation of DPSCs. In regard with this, DPSCs were incubated with growth and dopaminergic neuronal differentiation medium with or without melatonin (10 μM) for 21 days. The morphological changes were followed by phase contrast microscopy and differentiation of DPSCs was evaluated by immunofluorescence labelling with NeuN, GFAP, and tyrosine hydroxylase. Furthermore, we evaluated the presence of neural progenitor cells by nestin immunoreactivity. Hippo signaling pathway was investigated by evaluating the immunoreactivity of YAP and p-YAP^Y357. Our results were also supported by western-blot analysis and SOX2, PCNA and caspase-3 were also evaluated. The positive immunoreactivity for NeuN, tyrosine hydroxylase and negative immunoreactivity for GFAP showed the successful differentiation of DPSCs to neurons, not glial cells. Melatonin addition to dopaminergic media induced tyrosine hydroxylase and decreased significantly nestin expression. The expressions of PCNA and caspase-3 were also decreased significantly with melatonin addition into growth media. Melatonin treatment induced phosphorylation of YAP^Y357 and reduced YAP expression. In conclusion, melatonin has potential to induce neuronal differentiation and reduce the proliferation of DPSCs by increasing phosphorylation of YAP^Y357 and eliminating the activity of YAP, which indicates the active state of Hippo signaling pathway.

Differentiation capacity of dental pulp stem cell into inner ear hair cell using an in vitro assay: a preliminary step toward treating sensorineural hearing loss

PURPOSE

Sensorineural hearing loss (SNHL) is commonly caused by the death or dysfunction of cochlear cell types as a result of their lack of regenerative capacity. However, regenerative medicine, such as stem cell therapy, has become a promising tool to cure many diseases, including hearing loss. In this study, we determined whether DPSCs could differentiate into cochlear hair cell in vitro.

METHODS

DPSCs derived from human third molar dental pulp were induced into NSCs using a medium containing basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) for 7 days, and then into cochlear hair cell using a medium containing EGF and IGF-1 for the next 14 days. We used the neuroepithelial protein marker nestin and cochlear hair cell marker myosin VIIa as the markers for cells differentiation. Cells expressing the positive markers under the microscope were confirmed to have differentiated into cochlear hair cell.

RESULTS

DPSCs were successfully induced to differentiate into NSCs, with mean 24% nestin-positive cells. We found that DPSC-derived NSCs have a great capacity in differentiating into inner ear hair cell-like cells with an average of 81% cells presenting myosin VIIa. Thus, DPSCs have high potential to serve as a good resource for SNHL treatment.

CONCLUSION

We found the high potential of DPSCs to differentiate into NSC. The ability of DPSCs in differentiating into neural lineage cell made them a good candidate for regenerative therapy in neural diseases, such as SNHL.

Methylglyoxal-Dependent Glycative Stress Is Prevented by the Natural Antioxidant Oleuropein in Human Dental Pulp Stem Cells through Nrf2/Glo1 Pathway

Methylglyoxal (MG) is a potent precursor of glycative stress (abnormal accumulation of advanced glycation end products, AGEs), a relevant condition underpinning the etiology of several diseases, including those of the oral cave. At present, synthetic agents able to trap MG are known; however, they have never been approved for clinical use because of their severe side effects. Hence, the search of bioactive natural scavengers remains a sector of strong research interest. Here, we investigated whether and how oleuropein (OP), the major bioactive component of olive leaf, was able to prevent MG-dependent glycative stress in human dental pulp stem cells (DPSCs). The cells were exposed to OP at 50 µM for 24 h prior to the administration of MG at 300 µM for additional 24 h. We found that OP prevented MG-induced glycative stress and DPSCs impairment by restoring the activity of Glyoxalase 1 (Glo1), the major detoxifying enzyme of MG, in a mechanism involving the redox-sensitive transcription factor Nrf2. Our results suggest that OP holds great promise for the development of preventive strategies for MG-derived AGEs-associated oral diseases and open new paths in research concerning additional studies on the protective potential of this secoiridoid.

Bovine-Derived Xenografts Immobilized With Cryopreserved Stem Cells From Human Adipose and Dental Pulp Tissues Promote Bone Regeneration: A Radiographic and Histological Study

Adipose tissue-derived stem cells (ADSCs) and dental pulp stem cells (DPSCs) have become promising sources for bone tissue engineering. Our study aimed at evaluating bone regeneration potential of cryopreserved ADSCs and DPSCs combined with bovine-derived xenografts with 10% porcine collagen. In vitro studies revealed that although DPSCs had higher proliferative abilities, ADSCs exhibited greater mineral depositions and higher osteogenic-related gene expression, indicating better osteogenic differentiation potential of ADSCs. After applying cryopreserved ADSCs and DPSCs in a critical-sized calvarial defect model, both cryopreserved mesenchymal stem cells significantly improved bone volume density and new bone area at 2, 4, and 8 weeks. Furthermore, the combined treatment with ADSCs and xenografts was more efficient in enhancing bone repair processes compared to combined treatment with DPCSs at all-time points. We also evaluated the sequential early bone healing process both histologically and radiographically, confirming a high agreement between these two methods. Based on these results, we propose grafting of the tissue-engineered construct seeded with cryopreserved ADSCs as a useful strategy in accelerating bone healing processes.

Advances and Perspectives in Dental Pulp Stem Cell Based Neuroregeneration Therapies

Human dental pulp stem cells (hDPSCs) are some of the most promising stem cell types for regenerative therapies given their ability to grow in the absence of serum and their realistic possibility to be used in autologous grafts. In this review, we describe the particular advantages of hDPSCs for neuroregenerative cell therapies. We thoroughly discuss the knowledge about their embryonic origin and characteristics of their postnatal niche, as well as the current status of cell culture protocols to maximize their multilineage differentiation potential, highlighting some common issues when assessing neuronal differentiation fates of hDPSCs. We also review the recent progress on neuroprotective and immunomodulatory capacity of hDPSCs and their secreted extracellular vesicles, as well as their combination with scaffold materials to improve their functional integration on the injured central nervous system (CNS) and peripheral nervous system (PNS). Finally, we offer some perspectives on the current and possible future applications of hDPSCs in neuroregenerative cell therapies.

Dental Pulp-Derived Mesenchymal Stem Cells for Modeling Genetic Disorders

A subpopulation of mesenchymal stem cells, developmentally derived from multipotent neural crest cells that form multiple facial tissues, resides within the dental pulp of human teeth. These stem cells show high proliferative capacity in vitro and are multipotent, including adipogenic, myogenic, osteogenic, chondrogenic, and neurogenic potential. Teeth containing viable cells are harvested via minimally invasive procedures, based on various clinical diagnoses, but then usually discarded as medical waste, indicating the relatively low ethical considerations to reuse these cells for medical applications. Previous studies have demonstrated that stem cells derived from healthy subjects are an excellent source for cell-based medicine, tissue regeneration, and bioengineering. Furthermore, stem cells donated by patients affected by genetic disorders can serve as in vitro models of disease-specific genetic variants, indicating additional applications of these stem cells with high plasticity. This review discusses the benefits, limitations, and perspectives of patient-derived dental pulp stem cells as alternatives that may complement other excellent, yet incomplete stem cell models, such as induced pluripotent stem cells, together with our recent data.

Different Approaches to the Regeneration of Dental Tissues in Regenerative Endodontics

(1) Background: The regenerative procedure has established a new approach to root canal therapy, to preserve the vital pulp of the tooth. This present review aimed to describe and sum up the different approaches to regenerative endodontic treatment conducted in the last 10 years; (2) Methods: A literature search was performed in the PubMed and Cochrane Library electronic databases, supplemented by a manual search. The search strategy included the following terms: “regenerative endodontic protocol”, “regenerative endodontic treatment”, and “regenerative endodontics” combined with “pulp revascularization”. Only studies on humans, published in the last 10 years and written in English were included; (3) Results: Three hundred and eighty-six potentially significant articles were identified. After exclusion of duplicates, and meticulous analysis, 36 case reports were selected; (4) Conclusions: The pulp revascularization procedure may bring a favorable outcome, however, the prognosis of regenerative endodontics (RET) is unpredictable. Permanent immature teeth showed greater potential for positive outcomes after the regenerative procedure. Further controlled clinical studies are required to fully understand the process of the dentin–pulp complex regeneration, and the predictability of the procedure.