Adult Dental Pulp Stem Cells Research Articles

Impact of Exposure to Commonly Used Carbamide Peroxide on Dental Pulp Stem Cells

Background: This study investigated the contact between adult dental pulp stem cells (DPSCs) and carbamide peroxide (CP), a bleaching agent that is a popular choice for at-home whitening products, using an in vitro model. Objectives: The aim of this study was to evaluate the impact of exposure to different concentrations and timings of a commonly used peroxide-based home tooth-whitening product on DPSCs. Materials and methods: Human DPSCs obtained from impacted third molars were cultured and exposed to various concentrations of carbamide peroxide (0.1%, 0.5%, and 1%). The effects of CP on DPSC proliferation and apoptosis were investigated by MTT assay and flow cytometry. Migration was investigated by micrographs of wound healing. An enzyme-linked immunosorbent assay (IL-6 and IL-8) was used to investigate the CP-stimulated cytokine production of DPSCs. Each experiment was performed three times with independent batches of DPSCs. Statistical analysis of the collected data was performed using one-way and two-way ANOVAs with the significance threshold set at p < 0.05. Tukey’s post hoc multiple comparison test was used to identify differences between groups. Results: Cell viability and adherence were lower in the CP-exposed cells compared to the non-stimulated cells, probably due to increased cell death (** p ≤ 0.01, **** p ≤ 0.0001). CP-stimulated DPSCs exhibited a dose-dependent release of IL-6 and IL-8 (**** p ≤ 0.0001). CP did not affect wound healing at any concentration tested. Conclusions: Human DPSCs were able to sense CP. Consequently, CP contributed significantly to cell apoptosis and local inflammatory responses through cytokine release.

Self-assembly of differentiated dental pulp stem cells facilitates spheroid human dental organoid formation and prevascularization.

The self-assembly of solid organs from stem cells has the potential to greatly expand the applicability of regenerative medicine. Stem cells can self-organise into microsized organ units, partially modelling tissue function and regeneration. Dental pulp organoids have been used to recapitulate the processes of tooth development and related diseases. However, the lack of vasculature limits the utility of dental pulp organoids. To improve survival and aid in recovery after stem cell transplantation, we demonstrated the three-dimensional (3D) self-assembly of adult stem cell-human dental pulp stem cells (hDPSCs) and endothelial cells (ECs) into a novel type of spheroid-shaped dental pulp organoid in vitro under hypoxia and conditioned medium (CM). During culture, primary hDPSCs were induced to differentiate into ECs by exposing them to a hypoxic environment and CM. The hypoxic pretreated hDPSCs were then mixed with ECs at specific ratios and conditioned in a 3D environment to produce prevascularized dental pulp organoids. The biological characteristics of the organoids were analysed, and the regulatory pathways associated with angiogenesis were studied. The combination of these two agents resulted in prevascularized human dental pulp organoids (Vorganoids) that more closely resembled dental pulp tissue in terms of morphology and function. Single-cell RNA sequencing of dental pulp tissue and RNA sequencing of Vorganoids were integrated to analyse key regulatory pathways associated with angiogenesis. The biomarkers forkhead box protein O1 and fibroblast growth factor 2 were identified to be involved in the regulation of Vorganoids. In this innovative study, we effectively established an in vitro model of Vorganoids and used it to elucidate new mechanisms of angiogenesis during regeneration, facilitating the development of clinical treatment strategies.

Challenge Tooth Regeneration in Adult Dogs with Dental Pulp Stem Cells on 3D-Printed Hydroxyapatite/Polylactic Acid Scaffolds.

Tooth regeneration is an important issue. The purpose of this study was to explore the feasibility of using adult dental pulp stem cells on polylactic acid scaffolds for tooth regeneration. Three teeth were extracted from each side of the lower jaws of two adult dogs. In the experimental group, dental pulp stem cells were isolated and seeded in the 3D-printed hydroxyapatite/polylactic acid (HA/PLA) scaffolds for transplantation into left lower jaw of each dog. The right-side jaw of each dog was transplanted with cell-free scaffolds as the control group. Polychrome sequentially labeling was performed for observation of mineralization. Dental cone beam computed tomography (CBCT) irradiation was used for assessment. Nine months after surgery, dogs were euthanized, and the lower jaws of dogs were sectioned and fixed for histological observation with hematoxylin and eosin staining. The results showed that the degree of mineralization in the experimental group with cells seeded in the scaffolds was significantly higher than that of the control group transplanted with cell-free scaffolds. However, the HA/PLA scaffolds were not completely absorbed in both groups. It is concluded that dental pulp stem cells are important for the mineralization of tooth regeneration. A more rapid absorbable material was required for scaffold design for tooth regeneration.

Cationic surface charge effect on proliferation and protein production of human dental pulp stem cells cultured on diethylaminoethyl-modified cellulose porous beads

Human adult dental pulp stem cells (DPSCs) are a type of mesenchymal stem cells (MSCs). Recently, DPSCs have been proposed as a new MSC source for treating immune-mediated, inflammatory, and degenerative diseases via cell-based therapy. Hence, large-scale industrial production of the required cell number will be necessary. In this study, to investigate the cationic surface charge effect on DPSC proliferation, we fabricated two types of 2-diethylaminoethyl -modified cellulose porous beads (CPB-DEAE) with different ion exchange capacities. The cationic surface charge effect increased with increase in DPSC proliferation rate for the ion exchange capacity of 0.55–1.82 meq/g. However, the DPSC proliferation rate decreased at 2.50 meq/g. Thus, the optimal ion exchange capacity was determined to be 1.82 meq/g for DPSC proliferation. Additionally, the total amount of protein produced from the DPSCs on the CPB-DEAE microcarriers was higher than that produced under the conventional monolayer culture conditions. Furthermore, the hepatocyte growth factor, which is one of the anti-inflammatory growth factors, was produced from the DPSCs on the CPB-DEAE microcarriers. Finally, the DPSCs were confirmed to maintain their proliferative and multidifferentiation ability after culture on the CPB-DEAE microcarriers. CPB-DEAE microcarriers have the potential to be used for large-scale MSC expansion and protein production.

Lipoteichoic acid stimulates the proliferation, migration and cytokine production of adult dental pulp stem cells without affecting osteogenic differentiation.

To model in vitro the contact between adult dental pulp stem cells (DPSCs) and lipoteichoic acid (LTA), a cell wall component expressed at the surface of most Gram-positive bacteria. Human DPSCs obtained from impacted third molars were cultured and exposed to various concentrations of S.aureus LTA (0.1, 1.0 and 10µgmL-1 ). The effects of LTA on DPSCs proliferation and apoptosis were investigated by MTT assay and flow cytometry. Mineralization of DPSCs was evaluated by alizarin red staining assay. Migration was investigated by microphotographs of wound-healing and Transwell migration assays. Reverse transcription polymerase chain reaction was used to examine the effects of LTA on p65 NF-κB translocation and TLR1, TLR2 or TLR6 regulation. Enzyme-linked immunosorbent assay was used to investigate LTA-stimulated DPSCs cytokine production. One-way or two-way ANOVA and Tukey post hoc multiple comparison were used for statistical analysis. DPSCs expressed TLR1, TLR2 and TLR6 involved in the recognition of various forms of LTA or lipoproteins. Exposure to LTA did not up- or down-regulate the mRNAs of TLR1, TLR2 or TLR6 whilst LPS acted as a potent inducer of them [TLR1 (P≤0.05), TLR2 (P≤0.001) and TLR6 (P≤0.001)]. Translocation of p65 NF-κB to the nucleus was detected in LTA-stimulated cells, but to a lesser extent than LPS-stimulated DPSCs (P≤0.001). The viability of cells exposed to LTA was greater than unstimulated cells, which was attributed to an increased proliferation and not to less cell death [LTA 1μgmL-1 (P≤0.001) and 10μgmL-1 (P≤0.01)]. For specific doses of LTA (1.0µgmL-1 ), adhesion of DPSCs to collagen matrix was disturbed (P≤0.05) and cells enhanced their horizontal mobility (P≤0.001). LTA-stimulated DPSCs released IL-6 and IL-8 in a dose-dependent manner (P≤0.0001). At all concentrations investigated, LTA did not influence osteogenic/odontoblastic differentiation. Human DPSCs were able to sense the wall components of Gram-positive bacteria likely through TLR2 signalling. Consequently, cells modestly proliferated, increased their migratory behaviour and contributed significantly to the local inflammatory response through cytokine release.

LncRNA CCAT1 promotes cell proliferation and differentiation via negative modulation of miRNA-218 in human DPSCs.

To investigate the expression of Long non-coding RNA (LncRNA) CCAT1 and potential functions in promoting cell proliferation and differentiation, via miRNA-218 in human adult Dental Pulp Stem Cells (DPSCs). CCAT1 expressions in Periodontal Ligament Cells (PDLCs), DPSCs, differentiated main population (MP) cells and stem-cell-enriched Side Population (SP) cells in DPSCs were detected by qRT-PCR. MTT assay and ELISA assay were performed to evaluate the DPSCs cell proliferation and differentiation. The correlation between miR-218 and CCAT1 was detected by statistical analysis. The bioinformatics and luciferase assay were performed to explore the interaction and binding site of CCAT1 and miR-218. Results showed the CCAT1 expression was up-regulated in DPSCs cells. And the expression level in MP cell was higher than SP cell. MTT assay and showed overexpression CCAT1 significantly increased cell proliferation of DPSCs. ELISA assay showed the expressions of collagen I, Osteopontin (OPN) and Osteocalcin (OCN) were significantly increased in DPSCs compared with control (p<0.05). The bioinformatics and luciferase assay showed that the CCAT1 directly interacted with miR-218. In addition, miR-218 expression was negatively correlated with CCAT1 expression in DPSCs CONCLUSIONS: For the first time, we found that lncRNA-CCAT1 was upregulated in DPSCs, which could promote cell proliferation and differentiation by repressing the expression of miR-218.

Enzymatic Isolation, Amplification and Characterization of Dental Pulp Stem Cells

The dental pulp represents an easily accessible source of adult dental pulp stem cells (DPSCs). The preferred approach to DPSC isolation is enzymatic digestion. However, the duration of the enzymatic activity is crucial. The purpose of this study was to isolate the DPSC populations using this method, characterize their biological properties and proliferation capacity, and to determine their ability to differentiate into mature cells. Before enzymatic digestion using 0.05% trypsin, we used the homogenization method in order to obtain a fine homogenate from the solid pulp tissue. The stem cells were cultivated in modified cultivation medium for mesenchymal adult progenitor cells containing 2% foetal bovine serum, growth factors and insulin-transferrin-selenium supplement. We were successfully able to isolate 10 populations of DPSCs. The vitality of DPSCs did not drop below 90 %. However, the DPSCs showed a significant decrease in the relative telomere length number with increasing passaging (P &lt; 0.05). Isolated DPSCs highly expressed the CD markers: CD29, CD44, CD90, CD13, CD73 and CD166. In contrast, CD markers CD31, CD106, CD34 and CD45 were negative or low positive. We confirmed the high osteogenic and chondrogenic potential of the isolated stem cells. Isolated DPSCs did not show signs of cell degeneration or spontaneous differentiation during the entire cultivation. In addition, we were able to shorten the enzyme activity duration, and we were the first to demonstrate trypsin as the enzyme used for the enzymatic digestion method with the viability over 90 % of isolated DPSCs using this method.

MicroRNA-139-5p elevates skeletal myogenic differentiation of human adult dental pulp stem cells through Wnt/β-catenin signaling pathway.

The aim of the present study was to identify a microRNA (miRNA or miR)-based biomarker and therapeutic target for skeletal myogenic differentiation of human adult dental pulp stem cells (ADSCs). miRNA expression was measured using reverse transcription-quantitative polymerase chain reaction; cell viability assay and lactate dehydrogenase (LDH) activity levels were measured using MTT and LDH activity kits, respectively. Apoptosis assay and caspase-3/9 activity levels were measured using flow cytometry and caspase-3/9 activity kits, respectively. Western blot analysis and immunofluorescence microscopy measured the protein expression of myocyte-specific enhancer factor 2C, myogenic differentiation 1, myosin heavy chain, Wnt and β-catenin. Overexpression of miR-139-5p promoted cell growth and induced skeletal myogenic differentiation of ADSCs. Downregulation of miR-139-5p inhibited cell growth and reduced skeletal myogenic differentiation of ADSCs. Overexpression of miR-139-5p induced Wnt/β-catenin signaling pathway and Wnt/β-catenin signaling pathway was suppressed by anti-miR-139-5p in ADSCs. Wnt inhibitor reduced the effect of miR-139-5p on skeletal myogenic differentiation of ADSCs. In conclusion, miR-139-5p elevates skeletal myogenic differentiation of human ADSCs through the Wnt/β-catenin signaling pathway.

Comparative Analysis of Mesenchymal Progenitor Cells from Dental Pulp and Cord Tissue and their Potentiality Towards Trans-Differentiation

Objective: The objective of our study was to successfully isolate progenitor cells from dental pulp and umbilical tissue and perform a comparative investigation of their potential transdifferentiation into osteo- and neuronal-like cells. Methods: Progenitor cells were harvested from dental pulp tissue as well as cord tissue and cultured through explant culture method over the span of 4 weeks. Image-based cytometric analysis was done to determine the cell viability along with phenotypic analysis to validate the occurrence of stem cell surface markers such as CD13, CD29, CD31, CD34, CD45, CD73, CD90, CD105, HLA-DR, and HLA-ABC. After culturing mesenchymal progenitor cells, osteogenic and neurogenic differentiation potential of both tissue sources was studied. The cells were seeded in two different surfaces tissue culture treated dishes and titanium sheets and cultured along with osteogenic differentiation medium (for 28 days) and neurogenic differentiation medium (for 5 days). The osteogenic potential of the progenitor cells were checked with the detection of calcium deposits by Vonn Kossa staining and PCR studies were done to confirm the presence of osteogenic genes like BMP2, HDAC1, HNF1A. The neurogenic potential of the progenitors were phenotypically determined by the observation of neuronal cells in the culture medium. Post differentiation PCR studies were done to confirm the presence of neuronal genes like NESTIN, AGRIN, MAG, DAPDH, NF-M. Findings: Progenitor cells extracted from cord tissue and dental pulp were positive for markers such as CD13, CD29, CD73, CD90, and CD105 and were found negative for markers such CD31, CD34, CD45, and HLA-DR. Progenitors obtained from dental pulp tissue showed a higher expression of cell surface markers indicating a stronger mesenchymal lineage. After culturing progenitor cells in osteogenic differentiation specific medium, these cells were successfully differentiated into cells of osteogenic lineage. Within 28 days of culture calcium deposits were detected by Von kossa staining. The differentiated cells were also found positive for osteogenic markers such as BMP2, HDAC1, HNF1A.In neural differentiation, post day 5 of culture neurospheres of varying sizes were observed floating in the culture medium. The fraction of the cells differentiated into osteogenic and neurogenic lineages were higher in progenitor cells derived from dental pulp in comparison with umbilical cord tissue. The higher potentialityof progenitor cells derived from dental pulp for neurogenic trans-differentiation could be explained by the fact that human adult dental pulp stem cells residing within the perivascular niche are thought to originate from the migrating cranial neural crest cells. There was no difference observed in the osteogenic and neurogenic differentiation capabilities of mesenchymal cells when plated in a plastic dish or titanium surface. Improvement: In-depth studies needs to be carried out on progenitor cells from dental pulp tissues in order to enhance the clinical efficacy of stem cells based therapies.

Comparative Analysis of Mesenchymal Progenitor Cells from Dental Pulp and Cord Tissue and their Potentiality Towards Trans-Differentiation

Objective: The objective of our study was to successfully isolate progenitor cells from dental pulp and umbilical tissue and perform a comparative investigation of their potential transdifferentiation into osteo- and neuronal-like cells. Methods: Progenitor cells were harvested from dental pulp tissue as well as cord tissue and cultured through explant culture method over the span of 4 weeks. Image-based cytometric analysis was done to determine the cell viability along with phenotypic analysis to validate the occurrence of stem cell surface markers such as CD13, CD29, CD31, CD34, CD45, CD73, CD90, CD105, HLA-DR, and HLA-ABC. After culturing mesenchymal progenitor cells, osteogenic and neurogenic differentiation potential of both tissue sources was studied. The cells were seeded in two different surfaces tissue culture treated dishes and titanium sheets and cultured along with osteogenic differentiation medium (for 28 days) and neurogenic differentiation medium (for 5 days). The osteogenic potential of the progenitor cells were checked with the detection of calcium deposits by Vonn Kossa staining and PCR studies were done to confirm the presence of osteogenic genes like BMP2, HDAC1, HNF1A. The neurogenic potential of the progenitors were phenotypically determined by the observation of neuronal cells in the culture medium. Post differentiation PCR studies were done to confirm the presence of neuronal genes like NESTIN, AGRIN, MAG, DAPDH, NF-M. Findings: Progenitor cells extracted from cord tissue and dental pulp were positive for markers such as CD13, CD29, CD73, CD90, and CD105 and were found negative for markers such CD31, CD34, CD45, and HLA-DR. Progenitors obtained from dental pulp tissue showed a higher expression of cell surface markers indicating a stronger mesenchymal lineage. After culturing progenitor cells in osteogenic differentiation specific medium, these cells were successfully differentiated into cells of osteogenic lineage. Within 28 days of culture calcium deposits were detected by Von kossa staining. The differentiated cells were also found positive for osteogenic markers such as BMP2, HDAC1, HNF1A.In neural differentiation, post day 5 of culture neurospheres of varying sizes were observed floating in the culture medium. The fraction of the cells differentiated into osteogenic and neurogenic lineages were higher in progenitor cells derived from dental pulp in comparison with umbilical cord tissue. The higher potentialityof progenitor cells derived from dental pulp for neurogenic trans-differentiation could be explained by the fact that human adult dental pulp stem cells residing within the perivascular niche are thought to originate from the migrating cranial neural crest cells. There was no difference observed in the osteogenic and neurogenic differentiation capabilities of mesenchymal cells when plated in a plastic dish or titanium surface. Improvement: In-depth studies needs to be carried out on progenitor cells from dental pulp tissues in order to enhance the clinical efficacy of stem cells based therapies.

Characterization of p75 neurotrophin receptor expression in human dental pulp stem cells

Human adult dental pulp stem cells (DPSC) are a heterogeneous stem cell population, which are able to differentiate down neural, chondrocyte, osteocyte and adipocyte lineages. We studied the expression pattern of p75 neurotrophin receptors (p75NTR), a marker of neural stem cells, within human DPSC populations from eight donors. p75NTR are expressed at low levels (<10%) in DPSC. Importantly, p75+ DPSC represent higher expression levels of SOX1 (neural precursor cell marker), SOX2 (cell pluripotency marker) and nestin (neural stem cell marker) in comparison to p75− DPSC. Our results suggest that p75+ hDPSC may denote a subpopulation with greater neurogenic potential.

High-plasticity mesenchymal stem cells isolated from adult-retained primary teeth and autogenous adult tooth pulp—A potential source for regenerative therapies?

PurposeThe objective of this study was to compare the growth rate, morphology, immunohistology and plasticity of autogenous adult-retained SHEDs (arSHEDs) and adult dental pulp stem cells (DPSCs) obtained from the same donor. MethodsExpression of the mesenchymal stem cell markers CD44, CD90, CD105, caspase-3 and GAPDH were assessed using RT-PCR. Caspase-3 and CD44 were also evaluated at the protein level by western blotting of cell lysates. Plasticity of DPSCs and arSHEDs were tested by culture in adipogenic, chondrogenic, osteogenic and Schwann cells induction media. ResultsDPSCs and arSHEDs were isolated by explant culturing and were similarly positive for growth rate and all tested markers. Furthermore, DPSCs and arSHEDs could be driven to adipocyte, chondrocyte, osteocyte and Schwann cells lineages thus indicating similar plasticity as precursor cells. ConclusionThis study demonstrates the similarities between DPSCs and arSHEDs in a unique situation, where both stem cells (SC) types were obtained from a single patient and thus represent an alternative source of SC’s for tissue engineering and regeneration.

Adult human dental pulp stem cells promote blood–brain barrier permeability through vascular endothelial growth factor-a expression

Stem cell therapy is a promising new treatment option for stroke. Intravascular administration of stem cells is a valid approach as stem cells have been shown to transmigrate the blood–brain barrier. The mechanism that causes this effect has not yet been elucidated. We hypothesized that stem cells would mediate localized discontinuities in the blood–brain barrier, which would allow passage into the brain parenchyma. Here, we demonstrate that adult human dental pulp stem cells express a soluble factor that increases permeability across an in vitro model of the blood–brain barrier. This effect was shown to be the result of vascular endothelial growth factor-a. The effect could be amplified by exposing dental pulp stem cell to stromal-derived factor 1, which stimulates vascular endothelial growth factor-a expression. These findings support the use of dental pulp stem cell in therapy for stroke.

MiR-143 and miR-135 inhibitors treatment induces skeletal myogenic differentiation of human adult dental pulp stem cells

ObjectiveDental pulp stem cells (DPSCs) possess pluripotent properties that allow them to differentiate into multiple cell lineages, which can be potentially used in tissue regeneration. The aim of this in vitro study is to explore the effect of miRNAs on the myogenic differentiation of human adult DPSCs and seek for some potential biological factors for stable and feasible application in DPSC myogenic differentiation. MethodsHuman adult DPSCs were isolated from normal impacted third molars were treated with 5-Aza-2′-deoxycytidine to induce to myogenic differentiation in vitro. During this process the levels of myomiRNAs and myogenic marker genes were detected by real-time qPCR and Western blotting. Then antisense oligonucleotides of miR-143 and miR-135 were transfected into DPSCs to explore their effects on myogenic differentiation. Gene expression detection and MyHC immunofluorescence microscopy analysis were applied to characterize the myogenic differentiation of DPSCs. ResultsExpression of miR-135 and miR-143 was markedly decreased in myoblast DPSCs induced by 5-Aza. Part of the DPSCs treated with miR-135 or miR-143 inhibitors showed apparent myocytic properties and eventually fused to form myotubes. Co-transfection of miR-135 and miR-143 inhibitors impelled half of DPSCs to form myotubes. ConclusionMiR-135 and miR-143 inhibitors could induce myogenic differentiation of DPSCs. Our findings indicated that miRNAs could exert a decisive function in induction of myogenic differentiation of DPSCs.

Comparison of osteo/odontogenic differentiation of human adult dental pulp stem cells and stem cells from apical papilla in the presence of platelet lysate

IntroductionHuman dental pulp cells (DPSCs) and stem cells from apical papilla have been used for the repair of damaged tooth tissues. Human platelet lysate (PL) has been suggested as a substitute for fetal bovine serum (FBS) for large scale expansion of dental stem cells. However, biological effects and optimal concentrations of PL for proliferation and differentiation of human dental stem cells remain to be elucidated. MethodologyDPSCs and SCAP cells were isolated from impacted third molars of young healthy donors, at the stage of root development and identified by markers using flow cytometry. For comparison the cells were cultured in media containing PL (1%, 5% and 10%) and FBS, with subsequent induction for osteogenic/odontogenic differentiation. The cultures were analyzed for; morphology, growth characteristics, mineralization potential (Alizarin Red method) and differentiation markers using ELISA and real time -polymerase chain reaction (qPCR). ResultsThe proliferation rates of DPSCs and SCAP significantly increased when cells were treated with 5% PL (7X doubling time) as compared to FBS. 5% PL also enhanced mineralized differentiation of DPSCs and SCAP, as indicated by the measurement of alkaline phosphatase activity, osteocalcin and osteopontin, calcium deposition and q-PCR. ConclusionOur findings suggest that using 5% platelet lysate, proliferation and osteo/odontogenesis of DPSCs and SCAP for a short period of time (15 days), was significantly improved. This may imply its use as an optimum concentration for expansion of dental stem cells in bone regeneration.

Immunomic Screening of Cell Surface Molecules on Undifferentiated Human Dental Pulp Stem Cells.

Human adult dental pulp tissue is a source of adult stem cells that have a potential to differentiate into various tissues, although the primary cell suspensions cultured from pulp tissue are mixtures of both stem cell and nonstem cell populations with heterogeneous phenotypes and various differentiation efficiencies. Therefore, cell surface protein markers on dental pulp stem cells are critical for detection and purification of stem cell populations. Yet, little is known about the cell surface molecules that are specifically associated with the undifferentiated and progenitor state of human adult dental pulp stem cells (hDPSCs). Presently, cell surface proteins expressed on hDPSCs were assessed by screening surface molecules specifically expressed on dentinogenic progenitors. Using a decoy immunization strategy, a set of monoclonal antibodies (MAbs) was generated against undifferentiated pulp progenitor cells. Forty-five hybridomas produced MAbs that interacted weakly, if at all, to differentiated pulp cells. Of these, 19 MAbs (18 IgG, 1 IgM) recognized surface molecules on undifferentiated hDPSCs. By multicolor flow cytometric analysis, 40%-60% of newly identified MAb-positive cells were demonstrated to be positive for the CD44 and CD90 mesenchymal markers. When MAb-positive cells were sorted from the heterogeneous pulp cell suspension, mineralization efficiency was increased three to five times compared with MAb-negative cells. The results suggest that the decoy immunization is an efficient method for isolation of MAbs against dentinogenic progenitors. These MAbs will be helpful for identification and enrichment of hDPSCs for efficient dentin regeneration.

Human dental pulp stem cells respond to cues from the rat retina and differentiate to express the retinal neuronal marker rhodopsin

Human adult dental pulp stem cells (DPSCs) are self-renewing stem cells that originate from the neural crest during development and remain within the dental pulp niche through adulthood. Due to their multi-lineage differentiation potential and their relative ease of access they represent an exciting alternative for autologous stem cell-based therapies in neurodegenerative diseases. In animal models, DPSCs transplanted into the brain differentiate into functional neurons or astrocytes in response to local environmental cues that appear to influence the fate of the surviving cells. Here we tested the hypothesis that DPSCs might be able to respond to factors present in the retina enabling the regenerative potential of these cells. We evaluated the response of DPSCs to conditioned media from organotypic explants from control and chemically damaged rat retinas. To evaluate cell differentiation, we analyzed the expression of glial fibrillary acidic protein (GFAP), early neuronal and retinal markers (polysialic acid-neural cell adhesion molecule (PSA-NCAM); Pax6; Ascl1; NeuroD1) and the late photoreceptor marker rhodopsin, by immunofluorescence and reverse transcription polymerase chain reaction (RT-PCR). Exposure of DPSC cultures to conditioned media from control retinas induced a 39% reduction on the number of DPSCs that expressed GFAP; the expression of Pax6, Ascl1, PSA-NCAM or NeuroD1 was undetectable or did not change significantly. Expression of rhodopsin was not detectable in control or after exposure of the cultures with retinal conditioned media. By contrast, 44% of DPSCs exposed to conditioned media from damaged retinas were immunopositive to this protein. This response could not be reproduced when conditioned media from Müller-enriched primary cultures was used. Finally, quantitative RT-PCR was performed to compare the relative expression of glial cell-derived neurotrophic factor (GDNF), nerve growth factor (NGF), ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF) in DPSC co-cultured with retinal organotypic explants, where BDNF mRNA expression was significantly upregulated in retinal-exposed cultures. Our data demonstrate that DPSC cultures respond to cues from the rat retina and differentiate to express retinal neuronal markers.

Dental Stem Cells

While the regeneration of a lost tissue is known to mankind for several years, it is only in the recent past that research on regenerative medicine/dentistry has gained momentum and eluded the dramatic yet scientific advancements in the field of molecular biology. The growing understanding of biological concepts in the regeneration of oral/dental tissues coupled with experiments on stem cells is likely to result in a paradigm shift in the therapeutic armamentarium of dental and oral diseases culminating in an intense search for “biological solutions to biological problems.” Stem cells have been successfully isolated from variety of human tissues including orofacial tissues. Mesenchymal stem cells (MSCs) are multipotent stem cells which differentiate into a variety of cell types. The potential MSCs for tooth regeneration mainly include stem cells from human exfoliated deciduous teeth (SHEDs), adult dental pulp stem cells (DPSCs), stem cells from apical part of the papilla (SCAPs), stem cells from the dental follicle (DFSCs), periodontal ligament stem cells (PDLSCs) and bone marrow derived mesenchymal stem cells (BMSCs). This review article outlines the recent progress in mesenchymal stem cells used in tooth regeneration.

Pancreatic Differentiation of Human Dental Pulp CD117 + stem cells

Adult stem cells cannot proliferate to produce enough cells for human transplantation with keeping stem cell characteristics shown in the primary culture. We established a novel culture protocol using human dental pulp stem cells (DPSCs) that can produce quantities sufficient for human transplantation. The present study assessed differentiation of DPSCs toward a pancreatic lineage in serum-free conditions, which is essential for safe transplantation. CD117⁺ stem cells were separated from human exfoliated deciduous teeth (stem cells from human exfoliated deciduous teeth; SHED) and adult DPSCs. The cells were characterized with real-time reverse-transcription PCR for a panel of embryonal lineage markers. 82 out of 84 markers were expressed in different levels in SHED or DPSCs. After pancreatic differentiation in vitro, we found expression of pancreatic-specific endocrine markers insulin, glucagon, somatostatin and pancreatic polypeptide, and exocrine marker amylase-2a in both cultures. We also found reprogramming in both cell cultures mimicking the embryonal stages of development of the pancreas. Transcription factors PDX1, HHEX, MNX1, NEUROG3, PAX4, PAX6 and NKX6-1, crucial markers for the pancreatic development, were all activated. Expression of these factors strongly implies that the cells differentiated toward a distinguished pancreatic lineage. Our results show that CD117⁺ SHED and DPSCs are capable of differentiation toward all functional endocrine and exocrine subsets of pancreatic cells in serum-free conditions. SHED and DPSCs may therefore have great potential for future cell therapy of pancreatic disorders.

The role of lysyl oxidase-like 2 in the odontogenic differentiation of human dental pulp stem cells.

Adult human dental pulp stem cells (hDPSCs) are a unique population of precursor cells those are isolated from postnatal dental pulp and have the ability to differentiate into a variety of cell types utilized for the formation of a reparative dentin-like complex. Using LC-MS/MS proteomics approaches, we identified the proteins secreted from the differentiating hDPSCs in mineralization media. Lysyl oxidase-like 2 (LOXL2) was identified as a protein that was down-regulated in the hDPSCs that differentiate into odontoblast-like cells. The role of LOXL2 has not been studied in dental pulp stem cells. LOXL2 mRNA levels were reduced in differentiating hDPSCs, whereas the levels of other LOX family members including LOX, LOXL1, LOXL3, and LOXL4, are increased. The protein expression and secretion levels of LOXL2 were also decreased during odontogenic differentiation. Recombinant LOXL2 protein treatment to hDPSCs resulted in a dose-dependent decrease in the early differentiation and the mineralization accompanying with the lower levels of odontogenic markers such as DSPP, DMP-1 and ALP. These results suggest that LOXL2 has a negative effect on the differentiation of hDPSCs and blocking LOXL2 can promote the hDPSC differentiation to odontoblasts.