The Four Pillars for Successful Regenerative Therapy in Endodontics: Stem Cells, Biomaterials, Growth Factors, and Their Synergistic Interactions.

Endodontics has made significant progress in regenerative approaches in recent years, thanks to advances in biologically based procedures or regenerative endodontic therapy (RET). In recent years, our profession has witnessed a clear conceptual shift in this therapy. RET was initially based on a blood clot induced by apical bleeding without harvesting the patient's cells or cell-free RET. Later, the RET encompassed the three principles of tissue engineering, stromal/stem cells, scaffolds, and growth factors, aiming for the regeneration of a functional dentin pulp complex. The regenerated dental pulp will recover the protective mechanisms including innate immunity, tertiary dentin formation, and pain sensitivity. This comprehensive review covers the basic knowledge and practical information for translational applications of stem cell-based RET and tissue engineering procedures for the regeneration of dental pulp. It will also provide overall information on the emerging technologies in biological and synthetic matrices, biomaterials, and signaling molecules, recent advances in stem cell therapy, and updated experimental results. This review brings useful and timely clinical evidence for practitioners to understand the challenges faced for a successful cell-based RET and the importance of preserving or reestablishing tooth vitality. The clinical translation of these current bioengineering approaches will undoubtedly be beneficial to the future practice of endodontics.

A new direction in managing avulsed teeth: stem cell-based de novo PDL regeneration.

Management of avulsed teeth after replantation often leads to an unfavorable outcome. Damage to the thin and vulnerable periodontal ligament is the key reason for failure. Cell- or stem cell-based regenerative medicine has emerged in the past two decades as a promising clinical treatment modality to improve treatment outcomes. This concept has also been tested for the management of avulsed teeth in animal models. This review focuses on the discussion of limitation of current management protocols for avulsed teeth, cell-based therapy for periodontal ligament (PDL) regeneration in small and large animals, the challenges of de novo regeneration of PDL on denuded root in the edentulous region using a mini-swine model, and establishing a prospective new clinical protocol to manage avulsed teeth based on the current progress of cell-based PDL regeneration studies.

Cell-derived Extracellular Matrix Proteins in Colloidal Microgel as a Self-Assembly Hydrogel for Regenerative Endodontics.

INTRODUCTION: This study investigated a colloidal microgel for angiogenic and odontogenic differentiation of cells in the presence of cell-derived extracellular matrix (ECM) proteins using a 3-dimensional culture model. METHODS: Viscoelastic properties of human dental pulp were determined to understand the native ECM environment. ECM proteins were extracted from dental pulp stem cell (DPSC) cultures, and MaxGel (Millipore Sigma, Burlington, MA) was used as a commercially available ECM protein. DPSCs were incubated in colloidal microgels in the presence of ECM proteins or gelatin methacryloyl (GelMA) as a bulk hydrogel (n = 9/group). The viability and odontogenic differentiation of DPSCs within hydrogels was determined using viability assays, mineralization staining, calcium and alkaline phosphatase assays, and quantitative polymerase chain reaction for odontogenic gene expression. Angiogenic properties of endothelial cells were determined using tubule formation assays and quantitative polymerase chain reaction to detect angiogenic gene expression. RESULTS: Dental pulp had a higher elastic modulus than the viscous modulus, showing a solidlike response similar to hydrogels. DPSC-derived ECM showed higher collagen and GAG than MaxGel (P < .05). The viability of DPSCs was similar in colloidal microgels, whereas higher cell viability, calcium deposition, and alkaline phosphatase activity were observed in GelMA (P < .05). Colloidal microgels allowed tubule-like structures by endothelial cells, whereas no tubular formation was observed in GelMA. DPSC-derived ECM in colloidal microgel up-regulated odontogenic gene expression, whereas MaxGel up-regulated angiogenic gene expression (P < .05). CONCLUSIONS: Colloidal microgels allowed cellular organization that can improve penetration and nutritional supply in a full-length root canal system. The bioactivity of cell-derived ECM proteins can be modified depending on the external stimulus.

Effects of intentionally treated water on the growth of mesenchymal stem cells: An exploratory study.

OBJECTIVE: This study explored if human primary mesenchymal stem cells (MSCs), derived from two donors and cultivated in a medium made with intentionally treated water, would exhibit more growth and pluripotency than MSCs from the same source but grown in untreated (control) water. DESIGN: To create the treated water, three Buddhist monks directed their attention toward commercially bottled water while holding the intention that the water would enhance the growth of MSCs. Under double-blind conditions, cell culture growth mediums were prepared with the treated and untreated water, which was in turn used to grow the primary MSCs. Primary cells obtained from two donors were designated as Cells #1 and Cells #2. The prediction was that treated water would result in increased cell proliferation, that more cells would enter the cell cycle growth phase, and that there would be increased expression of genes (NANOG, OCT4 and SOX2) associated with improved cell growth and decreased expression of genes (p16, p21, and p53) associated with a decline in cell growth. The improved growth hypothesis was directional, thus one-tailed p-values were used to evaluate the results. RESULTS: Proliferation averaged across Cells #1 and #2 showed overall increased growth in treated as compared to control water (p = 0.0008). Cells #1 and #2 considered separately had differences in the same direction but only Cells #2 showed a significant difference on day 6 (p = 0.01). For cell cycle, there was a significantly greater percentage of Cells #2 in the S interphase with treated vs. control water (p = 0.04). For the gene expression analysis, when considering the average across the two donor cells, only the NANOG gene expression was in the predicted direction (p = 0.01); by contrast, the p16 gene expression was significantly opposite to the predicted direction (p = 0.005, one-tailed, post-hoc). For Cells #1 considered separately, no differences were significant except for p16, which resulted in an effect opposite to the predicted outcome (p = 0.05). For Cells #2, three genes were significantly in the predicted directions: NANOG (p = 0.0008), OCT4 (p = 0.005), and P53 (p = 0.05); p16 was significantly opposite to the prediction (p = 0.001). CONCLUSION: Intentionally treated water appeared to have some biological effects on the growth, pluripotency and senescence of human MSCs. This was especially the case in one of the two donor cells tested, but the effects were not consistently in the predicted direction. As an exploratory study, caution is warranted in interpreting these outcomes, and adjustment for multiple testing would likely reduce some of the weaker effects to nonsignificant. But given the double-blind protocol, as well as several more significant outcomes in the predicted directions, further research is warranted.

Potential of tailored amorphous multiporous calcium silicate glass for pulp capping regenerative endodontics-A preliminary assessment.

INTRODUCTION/OBJECTIVE: The tailored amorphous multi-porous (TAMP) material fabrication technology has led to a new class of bioactive materials possessing versatile characteristics. It has not been tested for dental applications. Thus, we aimed to assess its biocompatibility and ability to regenerate dental mineral tissue. METHODS: 30CaO-70SiO2 model TAMP discs were fabricated by a sol-gel method followed by in vitro biocompatibility testing with isolated human or mini-swine dental pulp stem cells (DPSCs). TAMP scaffolds were tested in vivo as a pulp exposure (pin-point, 1 mm, 2 mm, and entire pulp chamber roof) capping material in the molar teeth of mini-swine. RESULTS: The in vitro assays showed that DPSCs attached well onto the TAMP discs with comparable viability to those attached to culture plates. Pulp capping tests on mini-swine showed that after 4.5 months TAMP material was still present at the capping site, and mineral tissue (dentin bridge) had formed in all sizes of pulp exposure underneath the TAMP material. CONCLUSIONS: TAMP calcium silicate is biocompatible with both human and swine DPSCs in vitro and with pulp in vivo, it may help regenerate the dentin bridge after pulp exposure.

Pulp/Dentin Regeneration: It Should Be Complicated.

Stem cell-mediated regenerative endodontics has reached the human clinical trial phase; however, many issues still exist that prevent such technology to be a widely used clinical practice. These issues are not straightforward and are complicated. They should be because pulp regeneration is dealing with a small dead-end space. In addition, when regeneration is needed, the space is often heavily infected. The true standard of pulp regeneration should be everything except generation of some fibrous connective tissue and amorphous mineral deposit. As of now, we are still far short of reaching the standard of complete vascularized and innervated pulp regeneration with newly formed tubular dentin in all types of teeth. Thus, we need to go back to the bench and use established animal models or create new animal models to tackle those issues. This article will address several key issues including the possibility of pulp regeneration in small canals of molar teeth by enhancing the neovascularization, and whether the organized tubular dentin can be generated on the canal walls. Data from our semi-orthotopic tooth fragment mouse model have shown that complete pulp regeneration using dental pulp stem cells (DPSCs) in small canal has been inconsistent because of limited blood supply. This inconsistency is similar in our orthotopic miniature swine model, although in some cases vascularized pulp-like tissue can be formed throughout the canal space after DPSC transplantation. Furthermore, no tubular dentin was observed in the orthotopic pulp regeneration, despite the fact that DPSCs have the capacity to generate some tubular dentin-like structure in the hydroxyapatite/tricalcium phosphate-mediated ectopic pulp/dentin formation model in mice. Potential strategies to be tested to address these regeneration issues are discussed herein.

Nanobubble-Enhanced Antimicrobial Agents: A Promising Approach for Regenerative Endodontics.

INTRODUCTION: In this study, we investigated the properties of nanobubble (NB) water and its effect on smear layer removal and strengthening the efficiency of disinfecting agents used in regenerative endodontic treatment. METHODS: NB water was generated in a NB Generator. The NB size, concentration, and pH were measured. Porcine teeth were enlarged to size 60 by using hand-files and irrigated with either NB water or 17% EDTA or received no further irrigation. The ability of irrigants to remove the smear layer was evaluated by using a scanning electron microscope (9 roots/group). Other samples (6 roots/group) were subjected to Vickers hardness test to determine the dentin microhardness. Autofluorescent tetracycline mixed with distilled water or NB water was placed inside the root canal space of porcine teeth, and the depth of medicament penetration into the dentinal tubules was visualized by using fluorescent stereomicroscope (5 roots/group). For the disinfection experiment, human roots were prepared, autoclaved, and inoculated with Enterococcus faecalis for 3 weeks. Canals were then disinfected by (1) standard needle irrigation (SNI) with 5.25% NaOCl, (2) 5.25% NaOCl with ultrasonication (US), (3) 5.25% NaOCl + XP finisher (XP), (4) SNI with 1.5% NaOCl, or (5) SNI with 1.5% NaOCl in NB water (5 roots/group). Teeth were split open and stained with LIVE/DEAD BackLight and visualized by using confocal laser scanning microscope (CLSM) at the coronal, middle, and apical thirds of the canal. The ratio of dead/total bacteria in the dentinal tubules at various depth levels (50, 100, and 150 µm) was calculated. RESULTS: NB water was more effective in removing smear layer than 17% EDTA and could allow infiltration of tetracycline into the dentinal tubule more than 1 mm. NB water did not alter the dentin microhardness compared with 17% EDTA (P < .05). At 50-µm depth, CLSM analysis showed no statistically significant difference between 1.5% NaOCl in NB water and 5.25% NaOCl with or without irrigation activation at the coronal, middle, and apical root segments (P > .05), ie, these groups had stronger bacterial killing than 1.5% NaOCl (P < .05). At deeper levels (100 and 150 µm), higher concentrations of NaOCl were more effective than 1.5% NaOCl with or without NB water. No statistically significant difference was noted between 5.25% NaOCl with and without irrigation activation at most depth levels (P > .05). CONCLUSIONS: NB water can allow smear layer removal and enhance tubular penetration of medicaments without changing dentin microhardness. In large canal models, NB water appears to improve the tubular disinfection capacity of lower concentration of NaOCl up to 50 µm. On the other hand, the use of irrigation activation (US or XP) did not provide any added disinfection into the dentinal tubules compared with SNI. These results suggest that NB water may be a promising adjunct to endodontic irrigants and medicaments.

Dens evaginatus: Current treatment options.

BACKGROUND: Teeth with dens evaginatus (DE) are more commonly observed in Western countries than previously. This is due to the increase in populations of patients of Asian origin, in whom DE is more common than in people of European origin. The interest in DE has also increased with the introduction of a procedure called regenerative endodontics. CASE DESCRIPTION: A narrative review of treatment options for teeth with DE is presented, based on pulpal conditions and maturity of the teeth. PRACTICAL IMPLICATIONS: Early recognition of teeth with DE allows for treatment choices that generally lead to good outcomes and can aid in preserving developing teeth in young patients.

Dental Mesenchymal Stem Cells: Dental Pulp Stem Cells, Periodontal Ligament Stem Cells, Apical Papilla Stem Cells, and Primary Teeth Stem Cells-Isolation, Characterization, and Expansion for Tissue Engineering.

Dental stem cells (DSCs) have been shown to possess great potential for multiple biomedical applications, especially for dental tissue regeneration. They are a special type of subpopulation of mesenchymal stem/stromal cells (MSCs) and present subtle differences from other types of MSCs. Therefore, it requires a specialized expertise to isolate, culture, and characterize these cells in vitro and in vivo. The purpose of this chapter is to share our experience in studying these cells. We will describe in detail laboratory protocols outlining how the cells are isolated, cultured, expanded, and characterized using various in vitro cellular and biochemical analyses, as well as an in vivo study model using immunocompromised mice to observe tissue regeneration after transplantation of these DSCs.

Effects of Restorative Materials on Dental Pulp Stem Cell Properties.

INTRODUCTION: Dental pulp stem cells (DPSCs) are multipotent progenitors for biotechnological practices, but the influences of existing restorations on their viability and differentiation are not well-known. This study was aimed to investigate in vivo and in vitro responses of DPSCs to restorative materials. METHODS: Class I cavities were prepared on molars scheduled to be extracted and then restored with a resin-based composite (RBC), a glass ionomer cement, or zinc oxide eugenol. Intact teeth were used as controls. Twelve molars in each group were extracted on day 7 or day 30 after restorations to assess the early or intermediate pulp responses and were then cut in half. One half was processed for histopathological analysis, and the other was used to isolate DPSCs for a colony-forming unit assay and real-time polymerase chain reaction for NANOG, OCT4, and CD44 expression. RESULTS: All restored teeth showed pulp damage at various levels, whereas mild to moderate inflammation persisted in the RBC group until day 30. The existence of DPSCs in the pulp cores of all groups was revealed based on CD44 immunoreactivity. Glass ionomer cement and zinc oxide eugenol did not affect the relative percentages of DPSCs in either early or intermediate stages, whereas RBCs reduced the percentage. The colony-forming units in all restoration groups were comparable with those in the control. Nevertheless, the restorations significantly enhanced OCT4 expression, especially in RBC/day 30. CONCLUSIONS: Dental restorations cause mild pulp damage but do not affect DPSC viability. RBC decreases DPSC densities but might increase the stemness of surviving DPSCs through an inflammation-stimulation process.

Animal Models for Stem Cell-Based Pulp Regeneration: Foundation for Human Clinical Applications.

IMPACT STATEMENT: Animal models are essential for tissue regeneration studies. This review summarizes and discusses the small and large animal models, including mouse, ferret, dog, and miniswine that have been utilized to experiment and to demonstrate stem cell-mediated dental pulp tissue regeneration. We describe the models based on the location where the tissue regeneration is tested-either ectopic, semiorthotopic, or orthotopic. Developing and utilizing optimal animal models for both mechanistic and translational studies of pulp regeneration are of critical importance to advance this field.

Human Dental Pulp Stem Cells and Gingival Mesenchymal Stem Cells Display Action Potential Capacity In Vitro after Neuronogenic Differentiation.

The potential of human mesenchymal stromal/stem cells (MSCs) including oral stem cells (OSCs) as a cell source to derive functional neurons has been inconclusive. Here we tested a number of human OSCs for their neurogenic potential compared to non-OSCs and employed various neurogenic induction methods. OSCs including dental pulp stem cells (DPSCs), gingiva-derived mesenchymal stem cells (GMSCs), stem cells from apical papilla and non-OSCs including bone marrow MSCs (BMMSCs), foreskin fibroblasts and dermal fibroblasts using non-neurosphere-mediated or neurosphere-mediated methods to guide them toward neuronal lineages. Cells were subjected to RT-qPCR, immunocytofluorescence to detect the expression of neurogenic genes or electrophysiological analysis at final stage of maturation. We found that induced DPSCs and GMSCs overall appeared to be more neurogenic compared to other cells either morphologically or levels of neurogenic gene expression. Nonetheless, of all the neural induction methods employed, only one neurosphere-mediated method yielded electrophysiological properties of functional neurons. Under this method, cells expressed increased neural stem cell markers, nestin and SOX1, in the first phase of differentiation. Neuronal-like cells expressed ßIII-tubulin, CNPase, GFAP, MAP-2, NFM, pan-Nav, GAD67, Nav1.6, NF1, NSE, PSD95, and synapsin after the second phase of differentiation to maturity. Electrophysiological experiments revealed that 8.3% of DPSC-derived neuronal cells and 21.2% of GMSC-derived neuronal cells displayed action potential, although no spontaneous excitatory/inhibitory postsynaptic action potential was observed. We conclude that DPSCs and GMSCs have the potential to become neuronal cells in vitro, therefore, these cells may be used as a source for neural regeneration.

Derivation and characterization of putative craniofacial mesenchymal progenitor cells from human induced pluripotent stem cells.

The introduction and widespread adoption of induced pluripotent stem cell (iPSC) technology has opened new avenues for craniofacial regenerative medicine. Neural crest cells (NCCs) are the precursor population to many craniofacial structures, including dental and periodontal structures, and iPSC-derived NCCs may, in the near future, offer an unlimited supply of patient-specific cells for craniofacial repair interventions. Here, we used an established protocol involving simultaneous Wnt signaling activation and TGF-ß signaling inhibition to differentiate three human iPSC lines to cranial NCCs. We then derived a mesenchymal progenitor cell (NCC-MPCs) population with chondrogenic and osteogenic potential from cranial NCCs and investigated their similarity to widely studied human postnatal dental or periodontal stem/progenitor cells. NCC-MPCs were quite distinct from both their precursor cells (NCCs) and bone-marrow mesenchymal stromal cells, a stromal population of mesodermal origin. Despite their similarity with dental stem/progenitor cells, NCC-MPCs were clearly differentiated by a core set of 43 genes, including ACKR3 (CXCR7), whose expression (both at transcript and protein level) appear to be specific to NCC-MPCs. Altogether, our data demonstrate the feasibility of craniofacial mesenchymal progenitor derivation from human iPSCs through a neural crest-intermediate and set the foundation for future studies regarding their full differentiation repertoire and their in vivo existence.

A Miniature Swine Model for Stem Cell-Based De Novo Regeneration of Dental Pulp and Dentin-Like Tissue.

The goal of this study was to establish mini-swine as a large animal model for stem cell-based pulp regeneration studies. Swine dental pulp stem cells (sDPSCs) were isolated from mini-swine and characterized in vitro. For in vivo studies, we first employed both ectopic and semi-orthotopic study models using severe combined immunodeficiency mice. One is hydroxyapatite-tricalcium phosphate (HA/TCP) model for pulp-dentin complex formation, and the other is tooth fragment model for complete pulp regeneration with new dentin depositing along the canal walls. We found that sDPSCs are similar to their human counterparts exhibiting mesenchymal stem cell characteristics with ability to form colony forming unit-fibroblastic and odontogenic differentiation potential. sDPSCs formed pulp-dentin complex in the HA/TCP model and showed pulp regeneration capacity in the tooth fragment model. We then tested orthotopic pulp regeneration on mini-swine including the use of multi-rooted teeth. Using autologous sDPSCs carried by hydrogel and transplanted into the mini-swine root canal space, we observed regeneration of vascularized pulp-like tissue with a layer of newly deposited dentin-like (rD) tissue or osteodentin along the canal walls. In some cases, dentin bridge-like structure was observed. Immunohistochemical analysis detected the expression of nestin, dentin sialophosphoprotein, dentin matrix protein 1, and bone sialoprotein in odontoblast-like cells lining against the produced rD. We also tested the use of allogeneic sDPSCs for the same procedures. Similar findings were observed in allogeneic transplantation. This study is the first to show an establishment of mini-swine as a suitable large animal model utilizing multi-rooted teeth for further cell-based pulp regeneration studies.

Comparison of sodium hypochlorite extrusion by five irrigation systems using an artificial root socket model and a quantitative chemical method.

OBJECTIVES: This is to compare the volumes of irrigant apically extruded by five irrigation systems in an artificial socket model simulating clinical conditions. MATERIALS AND METHODS: Twenty extracted human single-rooted teeth were enlarged to size 40/04 and then embedded in silicone impression material. The root canal space was irrigated with nominal 3% sodium hypochlorite (NaOCl) using standard needle irrigation (SNI) with a 30-gauge notched needle, EndoActivator (EA), XP Endo Finisher (XP Endo), EndoVac (EV), and photon-induced photoacoustic streaming (PIPS). Extruded NaOCl was collected, reacted with taurine to form taurine-monochloramine, and absorbance of taurine-monochloramine was measured at 252 nm using a spectrophotometer. The five irrigation systems were compared with repeated measures ANOVA and pairwise comparisons. RESULTS: The EV group had very low extrusion (mean ± SD = 0.12 ± 0.2 µL) and differed significantly from the other four groups (P ≤ 0.001). Larger volumes of irrigant were extruded in the other irrigation groups. There were no significant differences in the extruded volumes among the SNI (7.4 ± 3.4 µL), EA (7.0 ± 6.1 µL), and XP Endo (7.8 ± 4.1 µL) groups (P = 1). The PIPS group had the highest mean extruded volume (12.9 ± 6.8 µL) and differed significantly from SNI (P = 0.030), EV (P < 0.0005), and EA (P = 0.02), but not XP Endo (P = 0.154). CONCLUSION: Under the in vitro conditions of this study, irrigant extrusion appears unavoidable unless negative pressure irrigation such as EV is used. PIPS extrudes more irrigant than other systems, while SNI, EA, and XP Endo extrude similar volumes of irrigant. CLINICAL RELEVANCE: The findings help clinicians select the optimal irrigation system to avoid irrigant extrusion.

Human dental stem cell derived transgene-free iPSCs generate functional neurons via embryoid body-mediated and direct induction methods.

Induced pluripotent stem cells (iPSCs) give rise to neural stem/progenitor cells, serving as a good source for neural regeneration. Here, we established transgene-free (TF) iPSCs from dental stem cells (DSCs) and determined their capacity to differentiate into functional neurons in vitro. Generated TF iPSCs from stem cells of apical papilla and dental pulp stem cells underwent two methods-embryoid body-mediated and direct induction, to guide TF-DSC iPSCs along with H9 or H9 Syn-GFP (human embryonic stem cells) into functional neurons in vitro. Using the embryoid body-mediated method, early stage neural markers PAX6, SOX1, and nestin were detected by immunocytofluorescence or reverse transcription-real time polymerase chain reaction (RT-qPCR). At late stage of neural induction measured at Weeks 7 and 9, the expression levels of neuron-specific markers Nav1.6, Kv1.4, Kv4.2, synapsin, SNAP25, PSD95, GAD67, GAP43, and NSE varied between stem cells of apical papilla iPSCs and H9. For direct induction method, iPSCs were directly induced into neural stem/progenitor cells and guided to become neuron-like cells. The direct method, while simpler, showed cell detachment and death during the differentiation process. At early stage, PAX6, SOX1 and nestin were detected. At late stage of differentiation, all five genes tested, nestin, ßIII-tubulin, neurofilament medium chain, GFAP, and Nav, were positive in many cells in cultures. Both differentiation methods led to neuron-like cells in cultures exhibiting sodium and potassium currents, action potential, or spontaneous excitatory postsynaptic potential. Thus, TF-DSC iPSCs are capable of undergoing guided neurogenic differentiation into functional neurons in vitro, thereby may serve as a cell source for neural regeneration.

Combined Effects of Vascular Endothelial Growth Factor and Bone Morphogenetic Protein 2 on Odonto/Osteogenic Differentiation of Human Dental Pulp Stem Cells In Vitro.

INTRODUCTION: The purpose of this study was to investigate whether combined and concerted delivery of vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP-2) enhances odonto/osteogenic differentiation of human dental pulp stem cells (DPSCs) in vitro. METHODS: Various concentrations of VEGF and/or BMP-2 with or without the presence of odonto/osteogenic medium (OM) were added into DPSC cultures for 21 days. The mineral formation in cultures was evaluated using alizarin red stain (ARS). Optimal concentrations of VEGF and BMP-2 were codelivered to DPSCs for total of 21 days with the following experimental groups: (1) group 1: OM only, (2) group 2: OM + VEGF, (3) group 3: OM + BMP-2, and (4) group 4: OM + VEGF + BMP-2 (subgroup 4a: VEGF present the first 7 days, 4b: BMP-2 present the last 14 days, and 4c, both present for 21 days). Cultures were then subjected to quantitative ARS analysis or harvested for quantitative polymerase chain reaction analysis for the expression of core-binding factor alpha 1 (CBFA1), alkaline phosphatase (ALP), and dentin matrix protein 1 (DMP-1). RESULTS: No mineral formation was detected by ARS when VEGF and/or BMP-2 were used without OM. OM + VEGF, but not OM + BMP-2, formed more mineralization than OM (P < .05). In the codelivery groups, the highest mineralization was observed in OM + VEGF and subgroup 4a compared with OM or the other groups (P < .05). Quantitative polymerase chain reaction analysis showed that CBFA1, ALP, and DMP-1 levels were higher in groups 2, 3, and 4a compared with 4b and 4c (P < .05). CBFA1 expressed higher in groups 2, 3, and 4a compared with OM (P < .05). For ALP expression, only subgroup 4a expressed higher than OM (P < .05). No difference was detected between groups 2 and 3 (P > .05) in the expression of the 3 genes. CONCLUSIONS: VEGF addition in the early phase rather than a continuous presence of both VEGF and BMP-2 enhances odonto/osteogenic differentiation of DPSCs.

Human and Swine Dental Pulp Stem Cells Form a Vascularlike Network after Angiogenic Differentiation in Comparison with Endothelial Cells: A Quantitative Analysis.

INTRODUCTION: The aim of this study was to quantify vascular network formation capacity after angiogenic induction of human and swine dental pulp stem cells (DPSCs) in comparison with endothelial cells. METHODS: Primary human DPSCs or swine DPSCs were induced in endothelial growth medium for 7 days. The expression of the endothelial marker von Willebrand factor was determined by immunostaining. Induced DPSCs (iDPSCs) and noninduced DPSCs (niDPSCs) were seeded at different cell numbers onto Matrigel (BD Biosciences, San Jose, CA) for vascular network formation assays and analyzed after 4, 8, 12, and 18 hours in comparison with human microvascular endothelial cells (hMECs). Quantitative analysis of vascular tubule formation was performed using ImageJ software (National Institutes of Health, Bethesda, MD). The vascular network formation was also conducted by coculturing of niDPSCs and iDPSCs. RESULTS: Von Willebrand factor was detected by immunofluorescence in both niDPSCs and iDPSCs (human and swine). Time-lapse microscopic observation showed that the vascular network was formed by iDPSCs but not niDPSCs. After 4 hours, iDPSCs showed vascular network formation, whereas niDPSCs started to aggregate and formed clusters. Human iDPSCs displayed a similar capacity to form vascular networks in Matrigel compared with hMECs based on quantitative analysis. Swine iDPSCs had a higher capacity compared with human iDPSCs or hMECs (P < .05) in forming the network structures including segments, nodes, and mesh. A coculture experiment showed that human niDPSCs colocalized on the angiogenic tubules and vascular networks that were formed by human iDPSCs. CONCLUSIONS: Our findings indicate that iDPSCs in combination with their noninduced counterparts may be used as a future clinical strategy for enhancing angiogenesis during the process of pulp-dentin regeneration.

Stem Cells in Deciduous Teeth ­ Their Potential use in Medicine

The potency and quality of adult stem cells in our body is reversely proportional to our age. When stem cells were discovered in deciduous teeth, it has drawn much attention to the dental and medical fields. Because these cells are normally from children shedding teeth around ages 6-12, they are relatively more immature stem cells. The isolated stem cells from the pulp of deciduous teeth were named SHED (stem cells from exfoliated deciduous teeth) [1]. As other dental stem cells, SHED are a type of typical mesenchymal stromal/stem cells (MSCs) expressing CD146, CD105, CD73, CD29 and CD44; as well as expressing embryonic stem (ES) cell markers OCT4, NANOG, stage-specific embryonic antigens (SSEA-3, SSEA-4) and tumor recognition antigens (TRA-1-60 and TRA-1-81) [2].