Dental Pulp Stem Cell Therapy in Ischemic Stroke: A Meta-Analysis of Preclinical Studies.

OBJECTIVE: More preclinical research evidence has shown that dental pulp stem cells (DPSCs) transplantation is expected to promote the recovery of ischemic stroke (IS), but it still lacks an evidence-based analysis. The purpose of this study was to investigate the effects of DPSCs on neurological function and infarct size in Sprague-Dawley (SD) rats with middle cerebral artery embolization (MCAO). METHODS: According to PRISMA guidelines, the preclinical study of DPSCs in the treatment of IS was screened according to the inclusion and exclusion criteria, and the relevant data and quality were evaluated by two independent researchers; A meta-analysis of histological and behavioral results was performed. RESULTS: Seven studies were finally included, with quality evaluation scores ranging from 8 to 9. Four articles reported modified Neurological Severity Scores (mNSS), three studies reported rotarod test, and six studies reported infarct volume. Meta-analysis showed that the mNSS score decreased by 1.17 times, the rotarod test increased by 1.11 times and the volume of cerebral infarction decreased by 1.91 times in the DPSC group compared with the blank control group. CONCLUSION: Transplantation of DPSCs can significantly improve the neurological function of ischemic stroke and reduce the infarct volume.

Effects of the prevention of medication-related osteonecrosis of the jaw by local administration of a dental pulp stem cell-conditioned medium to the rat tooth extraction socket.

The onset of osteonecrosis of the jaw, which is a side effect of bisphosphonates, often develops after tooth extraction; measures for its prevention have not yet been established. While treatment with systemic administration of bone marrow stem cell-derived conditioned medium for medication-related osteonecrosis of the jaw (MRONJ) has been reported, its preventive effects have not been clarified yet, and the high degree of invasiveness of bone marrow fluid collection remains an issue. Therefore, we created a rat model of MRONJ using BP zoledronic acid, used a dental pulp stem cell-conditioned medium (DPSC-CM), which can be collected relatively easily, and locally applied it to the tooth extraction socket with atelocollagen and gelatin sponges. The preventive effect on the onset of MRONJ was subsequently examined. The results demonstrated that the bone exposure width of the extraction socket was reduced, and the mucosal covering was promoted in the atelocollagen + DPSC-CM group as compared with the other groups. Furthermore, histological results indicated a decrease in the number of empty bone lacunae, whereas immunohistochemical staining revealed the presence of many vascular endothelial growth factor (VEGF)-positive cells. Moreover, the results of the investigation of the sustained release of atelocollagen using VEGF indicated the release of VEGF over time. Our results suggest that local administration of DPSC-CM using atelocollagen may be a useful method for the prevention of MRONJ triggered by tooth extraction.

Evaluation of cytotoxicity impacts of combined methylene blue-mediated photodynamic therapy and intracanal antibiotic medicaments on dental stem cells.

Root canal therapy is a predominant method for treatment of dental pulp and periapical diseases. Conventional methods such as mechanical instrumentations, chemical irrigation and intracanal medicaments pose a huge limitation to root canal disinfection as they kill bacteria and dental stem cells simultaneously. Therefore, much attention has been focused on finding more efficacious antibacterial methods that has no or negligible cytotoxicity for dental stem cells. Herein, we hypothesized that combining antibacterial medicaments with Antimicrobial photodynamic therapy (aPDT) and methylene blue (MB) as a photosensitizer would be effective in reducing death of dental pulp stem cells (DPSCs). To examine this, DPSCs were isolated from third molar teeth through enzymatic digestion. Isolated cells were cultured in αMEM and when reached adequate confluency, were used for further analysis. Cytotoxicity effect of different groups of MB, DAP, MB, LED and their combination on DPSCs was analyzed using MTT assay. DPSCs membrane integrity as a marker of live cells was assessed through measuring lipid peroxidation and lactate dehydrogenase (LDH) release into extracellular space. Results showed that the combination of LED, MB and TAP or aPDT, MB and DAP was more effective in reducing DPSCs death rate compared to TAP and DAP administration alone. Moreover, Malondialdehyde (MDA) and LDH levels were found to be decreased in cells exposed to combination treatment in comparison with single TAP or DAP therapy. Our study shows the promising perspectives of employing combined aPDT, MB and antibiotic medicaments for reduction of dental stem cell death.

Administration of Epidermal Growth Factor (EGF) and Basic Fibroblast Growth Factor (bFGF) to Induce Neural Differentiation of Dental Pulp Stem Cells (DPSC) Isolates.

The aging populations in many countries have developed many chronic illnesses and diseases, including chronic neurologic conditions such as Parkinson's and Azheimer's diseases. Many new lines of research and treatment are focusing on the potential for neurologic regeneration using mesenchymal stem cells (MSCs) in the rapidly growing field of regenerative medicine. This may include dental pulp stem cells (DPSCs), which have recently been demonstrated to produce neuronal precursors. Based upon this evidence, the primary aim of this study was to determine if the growth factors used in MSC-based studies are sufficient to induce neuronal differentiation among DPSCs. Using an existing biorepository, n = 16 DPSC isolates were thawed and cultured for this study, which revealed several subpopulations of rapid-, intermediate-, and slowly dividing DPSCs. Administration of epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) were sufficient to induce differential changes in growth and viability mainly among some of the rapidly growing DPSCs (n = 4). These phenotypic changes included expression of neural differentiation markers including Sox1, Pax6 and NF-M, which were observed only among those DPSC isolates not expressing early odontoblast-specific biomarkers such as ALP and DSPP. Future studies will be needed to confirm if these methods are sufficient to induce consistent and reliable induction of DPSCs towards neuronal specific differentiation.

Differential Expression of MicroRNA (MiR-27, MiR-145) among Dental Pulp Stem Cells (DPSCs) Following Neurogenic Differentiation Stimuli.

This study sought to evaluate the expression of previously identified microRNAs known to regulate neuronal differentiation in mesenchymal stem cells (MSCs), including miR-27, miR-125, miR-128, miR-135, miR-140, miR-145, miR-218 and miR-410, among dental pulp stem cells (DPSCs) under conditions demonstrated to induce neuronal differentiation. Using an approved protocol, n = 12 DPSCs were identified from an existing biorepository and treated with basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF), which were previously demonstrated to induce neural differentiation markers including Sox1, Pax6 and NFM among these DPSCs. This study revealed that some microRNAs involved in the neuronal differentiation of MSCs were also differentially expressed among the DPSCs, including miR-27 and miR-145. In addition, this study also revealed that administration of bFGF and EGF was sufficient to modulate miR-27 and miR-145 expression in all of the stimulus-responsive DPSCs but not among all of the non-responsive DPSCs-suggesting that further investigation of the downstream targets of these microRNAs may be needed to fully evaluate and understand these observations.

Molecular Changes in Prader-Willi Syndrome Neurons Reveals Clues About Increased Autism Susceptibility.

Background: Prader-Willi syndrome (PWS) is a neurodevelopmental disorder characterized by hormonal dysregulation, obesity, intellectual disability, and behavioral problems. Most PWS cases are caused by paternal interstitial deletions of 15q11.2-q13.1, while a smaller number of cases are caused by chromosome 15 maternal uniparental disomy (PW-UPD). Children with PW-UPD are at higher risk for developing autism spectrum disorder (ASD) than the neurotypical population. In this study, we used expression analysis of PW-UPD neurons to try to identify the molecular cause for increased autism risk. Methods: Dental pulp stem cells (DPSC) from neurotypical control and PWS subjects were differentiated to neurons for mRNA sequencing. Significantly differentially expressed transcripts among all groups were identified. Downstream protein analysis including immunocytochemistry and immunoblots were performed to confirm the transcript level data and pathway enrichment findings. Results: We identified 9 transcripts outside of the PWS critical region (15q11.2-q13.1) that may contribute to core PWS phenotypes. Moreover, we discovered a global reduction in mitochondrial transcripts in the PW-UPD + ASD group. We also found decreased mitochondrial abundance along with mitochondrial aggregates in the cell body and neural projections of +ASD neurons. Conclusion: The 9 transcripts we identified common to all PWS subtypes may reveal PWS specific defects during neurodevelopment. Importantly, we found a global reduction in mitochondrial transcripts in PW-UPD + ASD neurons versus control and other PWS subtypes. We then confirmed mitochondrial defects in neurons from individuals with PWS at the cellular level. Quantification of this phenotype supports our hypothesis that the increased incidence of ASD in PW-UPD subjects may arise from mitochondrial defects in developing neurons.

Novel live cell fluorescent probe for human-induced pluripotent stem cells highlights early reprogramming population.

BACKGROUND: Despite recent rapid progress in method development and biological understanding of induced pluripotent stem (iPS) cells, there has been a relative shortage of tools that monitor the early reprogramming process into human iPS cells. METHODS: We screened the in-house built fluorescent library compounds that specifically bind human iPS cells. After tertiary screening, the selected probe was analyzed for its ability to detect reprogramming cells in the time-dependent manner using high-content imaging analysis. The probe was compared with conventional dyes in different reprogramming methods, cell types, and cell culture conditions. Cell sorting was performed with the fluorescent probe to analyze the early reprogramming cells for their pluripotent characteristics and genome-wide gene expression signatures by RNA-seq. Finally, the candidate reprogramming factor identified was investigated for its ability to modulate reprogramming efficiency. RESULTS: We identified a novel BODIPY-derived fluorescent probe, BDL-E5, which detects live human iPS cells at the early reprogramming stage. BDL-E5 can recognize authentic reprogramming cells around 7 days before iPS colonies are formed and stained positive with conventional pluripotent markers. Cell sorting of reprogrammed cells with BDL-E5 allowed generation of an increased number and higher quality of iPS cells. RNA sequencing analysis of BDL-E5-positive versus negative cells revealed early reprogramming patterns of gene expression, which notably included CREB1. Reprogramming efficiency was significantly increased by overexpression of CREB1 and decreased by knockdown of CREB1. CONCLUSION: Collectively, BDL-E5 offers a valuable tool for delineating the early reprogramming pathway and clinically applicable commercial production of human iPS cells.

Neuronal differentiation of dental pulp stem cells from human permanent and deciduous teeth following coculture with rat auditory brainstem slices.

Sensorineural hearing loss is a common disability found worldwide which is associated with a degeneration of spiral ganglion neurons (SGN). It is a challenge to restore SGN due to the permanent degeneration and viability of SGN is requisite for patients to receive an advantage from hearing aid devices. Human dental pulp stem cells (DPSC) and stem cells from human exfoliated deciduous teeth (SHED) are self-renewing stem cells that originate from the neural crest during development. These stem cells have a high potential for neuronal differentiation. This is primarily due to their multilineage differentiation potential and their relative ease of access. Previously, we have shown the ability of these stem cell types to differentiate into spiral ganglion neuron-like cells. In this study, we induced the cells into neural precursor cells (NPC) and cocultured with auditory brainstem slice (ABS) encompassing cochlear nucleus by the Stoppini method. We also investigated their ability to differentiate after 2 weeks and 4 weeks in coculture. Neuronal differentiation of DPSC-NPC and SHED-NPC was higher expression of specific markers to SGN, TrkB, and Gata3, compared to monoculture. The cells also highly expressed synaptic vesicle protein (SV2A) and exhibited intracellular calcium oscillations. Our findings demonstrated the possibility of using DPSCs and SHEDs as an autologous stem cell-based therapy for sensorineural hearing loss patients.

Study of the immunomodulatory effects of osteogenic differentiated human dental pulp stem cells.

BACKGROUND AND AIMS: Dental pulp stem cells (DPSC) are promising tools in regenerative medicine due to their differentiation potential and immunomodulatory properties. However, it is not clearly known whether or not DPSCs maintain their immunosuppressive effects after differentiation. In the present study, we examined the immunomodulatory effects of osteogenic differentiated DPSCs (OD-DPSCs). METHODS: OD-DPSCs and undifferentiated DPSCs were co-cultured with allogenic PBMCs in different ratios and the proliferation of the PBMCs was measured. The concentration of IL-10, TGF-ß, PGE2, IL-6, and NO were then examined. Moreover, the expression of IDO, HLAG, and HGF genes were determined in undifferentiated and OD-DPSCs. FINDINGS: The results showed that OD-DPSCs could inhibit the proliferation of allogenic PBMCs. The levels of PGE2, IL-6, and TGF-ß anti-inflammatory cytokines increased after the co-culture. Moreover, the levels of NO increased during the differentiation process and the expression of IDO, HLAG, and HGF genes remained unchanged after osteogenic differentiation. SIGNIFICANCE: Although, there were some differences between the OD-DPSCs and undifferentiated DPSCs in terms of their cytokine and NO production, undifferentiated DPSCs maintained their immunomodulatory activities upon differentiation.

Establishing methods for isolation of stem cells from human exfoliated deciduous from carious deciduous teeth.

AIM: This study aims to establish the isolation method of stem cells from pulp tissue of carious deciduous teeth. METHODS: The teeth were soaked in 1% povidone-iodine solution for about 1 min followed by washing in PBS with 1% antibiotic-antimycotic thrice. Dental pulp tissue was removed by extirpation, and then cultivated in the culture medium. Characterization of mesenchymal stem cell (MSC) was carried out using human MSC analysis kit with positive markers CD90, CD73, and CD105, but negative for expressions of CD45, CD34, CD11b, CD19, and HLA-DR. Differentiation capacity of stem cells from human exfoliated deciduous (SHED) was determined by staining with Alizarin S, Alcian Blue, and Oil Red O. RESULTS: There is no contamination after 3 days of culture. SHED derived from dental pulp were expressions of 99.2% of positive marker and 0.3% of the negative marker. At passage 5, SHED was differentiated into osteocyte, chondrocyte, and adipocyte types of cells in the induction medium. CONCLUSION: SHED derived from carious deciduous teeth can be used as a source of stem cell for regenerative medicine.

Immunohistochemical characterization of stem cell and differentiation markers of the dental pulp of human natal teeth.

AIM: Dental pulp stem cells, which are primarily derived from the pulp tissues of human teeth, have rarely been obtained from natal teeth. This study investigated the stem cell and differentiation markers of the dental pulp of natal teeth using immunohistochemistry. MATERIALS & METHODS: The pulp tissue from extracted natal teeth (n = 2) of a 20-day-old healthy male was examined for immunohistochemical expression of stem cell (Oct-4 and SOX 2) and differentiation markers (Nestin, CD 44, desmin, osteopontin and Ki- 67). RESULTS: The pulp tissue of the natal teeth expressed immunopositivity for nestin, CD 44 and SOX2. CONCLUSION: Natal teeth, if preserved properly, could serve as sources of dental pulp stem cells that are an improvement on deciduous teeth.

Differentiation of dental pulp stem cells into chondrocytes upon culture on porous chitosan-xanthan scaffolds in the presence of kartogenin.

Adhesion, proliferation and differentiation of dental pulp stem cells (DPSCs) into chondrocytes were investigated in this work with the purpose of broadening the array of cell alternatives to the therapy of cartilage lesions related to tissue engineering approaches. A porous chitosan-xanthan (C-X) matrix was used as scaffold and kartogenin was used as a selective chondrogenic differentiation promoter. The scaffold was characterized regarding aspect and surface morphology, absorption and stability in culture medium, thickness, porosity, thermogravimetric behavior, X-ray diffraction, mechanical properties and indirect cytocompatibility. The behavior of DPSCs cultured on the scaffold was evaluated by scanning electron microscopy and cell differentiation, by histological analysis. A sufficiently stable amorphous scaffold with mean thickness of 0.89±0.01mm and high culture medium absorption capacity (13.20±1.88g/g) was obtained, and kartogenin concentrations as low as 100nmol/L were sufficient to efficiently induce DPSCs differentiation into chondrocytes, showing that the strategy proposed may be a straightforward and effective approach for tissue engineering aiming at the therapy of cartilage lesions.