Evaluation of Osteogenic/Cementogenic Modulating Potential of PAI-1 Transfected Media for Stem Cells.

AIM OF THE STUDY: In vitro evaluation of the effects of plasminogen activator inhibitor-1 (PAI-1) transfected-conditioned media (P-CM) on the differentiation of human periodontal ligament stem cells (hPDLSCs) and human periapical follicular stem cells (hPAFSCs). MATERIALS AND METHODS: The hPDLSCs and hPAFSCs received from impacted third molars were treated with P-CM and viability, as well as differentiation of the cells were evaluated. Plasmids were constructed according to standard techniques, and all sequences were validated by proper enzyme digestion and sequencing. Chinese hamster ovarian (CHO) cells were transfected with pcDNA3.1-hPAI-1 plasmid to obtain P-CM, followed by western blotting and PAI-1-specific ELISA kit to evaluate the proteins of P-CM. The cell viability of hPDLSCs and hPAFSCs were analyzed using MTT assay after 48 h of incubation. Alizarin red S staining was performed to evaluate the differentiation of hPDLSCs and hPAFSCs. The reverse transcription-polymerase chain reaction was used to observe the expression levels of osteogenic/cementogenic marker genes. The human cytokine antibody array was applied for further analysis of cytokine expression in P-CM. RESULTS: P-CM significantly promoted the differentiation of hPDLSCs and hPAFSCs and upregulated the expression of osteogenic/cementogenic marker genes in vitro. Furthermore, rhPAI-1 promoted mineralized nodules formation of hPDLSCs and hPAFSCs, and we identified that other proteins, RANTES and IL-6, were highly expressed in P-CM. CONCLUSIONS: P-CM promoted the differentiation of hPDLSCs and hPAFSCs by upregulating the expression of RANTES and IL-6, and interaction between PAI-1 and RANTES/IL-6 signaling may be involved in P-CM-induced osteogenic/cementogenic differentiation.

A comparison of the sealing abilities between Biodentine and MTA as root-end filling materials and their effects on bone healing in dogs after periradicular surgery.

OBJECTIVES: To compare the sealing ability and biocompatibility of Biodentine with mineral trioxide aggregate (MTA) when used as root-end filling materials. METHODOLOGY: The Cell Counting Kit-8 (CCK-8) assay was used to compare the cytotoxicity of MTA and Biodentine. Twenty-one extracted teeth with a single canal were immersed in an acidic silver nitrate solution after root-end filling. Then, the volume and depth of silver nitrate that infiltrated the apical portion of the teeth were analyzed using micro-computed tomography (micro-CT). Seventy-two roots from 3 female beagle dogs were randomly distributed into 3 groups and apical surgery was performed. After six months, the volume of the bone defect surrounding these roots was analyzed using micro-CT. RESULTS: Based on the results of the CCK-8 assay, MTA and Biodentine did not show statistically significant differences in cytotoxicity (P>0.05). The volume and the depth of the infiltrated nitrate solution were greater in the MTA group than in the Biodentine group (P<0.05). The volume of the bone defect was larger in the MTA group than in the Biodentine group. However, the difference was not significant (P>0.05). The volumes of the bone defects in the MTA and Biodentine groups were smaller than the group without any filling materials (P<0.05). CONCLUSIONS: MTA and Biodentine exhibited comparable cellular biocompatibility. Biodentine showed a superior sealing ability to MTA in root-end filling. Both Biodentine and MTA promoted periradicular bone healing in beagle dog periradicular surgery models.

MiR-141-3p regulates proliferation and senescence of stem cells from apical papilla by targeting YAP.

Biological phenotypes of mesenchymal stem cells (MSCs) are regulated by a series of biochemical elements, including microRNAs, hormones and growth factors. Our previous study illustrated a significant role of miR-141-3p during the osteogenic differentiation of stem cells from apical papilla (SCAPs). Nevertheless, the functions of miR-141-3p in regulating the proliferative ability and senescence of SCAPs have not been determined. This study identified that overexpression of miR-141-3p inhibited the proliferative ability of SCAPs. Meanwhile, the senescence of SCAPs was ahead of time. Conversely, transfection of miR-141-3p inhibitor promoted the proliferative ability of SCAPs and delayed their senescence. Yes-associated protein (YAP) was predicted as the downstream target gene of miR-141-3p by online softwares (miRDB, miRTarBase, miRWalk, and TargetScan), and was further verified by dual-luciferase reporter gene assay. Additionally, knockdown of YAP inhibited the proliferation and accelerated the senescence of SCAPs. Collectively, these findings proposed a novel direction that miR-141-3p impeded proliferative ability and promoted senescence of SCAPs through post-transcriptionally downregulating YAP.

Puesta al día en regeneración pulpar / An update on pulp regeneration in endodontics

Cuando se combinan entre sí, las células madre, las matrices y los factores de crecimiento tienen la capacidad de regenerar un tejido, tal como el complejo dentino-pulpar. La ingeniería tisular está adquiriendo cada vez más importancia en el campo de la endodoncia como una alternativa a la obturación clásica con gutapercha. El objetivo de esta revisión es comparar los diferentes materiales que actuarían como matrices disponibles en la actualidad, así como conocer el alcance del conocimiento sobre los factores de crecimiento relacionados con la regeneración de la pulpa, señalando las principales limitaciones y elaborando un protocolo para futuros procedimientos regenerativos. Las matrices de colágeno han demostrado ser una opción óptima, ya que son biodegradables, pueden ser autólogos y existe una alta disposición. El factor de crecimiento insulínico tipo 1 y el factor de crecimiento derivado de plaquetas han demostrado estar implicados en la proliferación celular. El factor de crecimiento endotelial vascular es uno de los más importantes para la proliferación de la red vascular. El aislamiento celular y los altos costos son los principales obstáculos. La combinación de un andamio de colágeno, factor de crecimiento insulínico tipo 1, factor de crecimiento derivado de plaquetas, factor de crecimiento endotelial vascular y células madre de tejido pulpar de dientes deciduos (SHEDs) podría dar buenos resultados en la regeneración de la pulpa dental

When combined together, stem cells, scaffolds and growth factors have the ability of regenerating a whole tissue, for example the dental-pulp complex. Tissue engineering is getting more and more importance in the endodontic field as an alternative to the standard filling of root canals with gutta-percha material. The aim of this review is to compare the different scaffold materials available today, find out the extent of knowledge about the growth factors related to pulp regeneration, pointing out the main limitations and devise a protocol for future regenerative procedures. Collagen scaffolds material have shown to be an optimal choice as they are biodegradable, can be autologous and are highly available. Insulin-like growth factor 1 and platelet derived growth factor have shown to be involved in cells proliferation. Vascular endothelial growth factor is one of the most important for vascular network proliferation. Cells isolation and high costs are the main obstacles. As a conclusion, the combination of a collagen scaffold, insulin-like growth factor 1, platelet derived growth factor, vascular endothelial growth factor and dental pulp stem cells from deciduous teeth (SHEDs) might give good outcomes in dental pulp regeneration

A comparison of the sealing abilities between Biodentine and MTA as root-end filling materials and their effects on bone healing in dogs after periradicular surgery

ABSTRACT Objectives: To compare the sealing ability and biocompatibility of Biodentine with mineral trioxide aggregate (MTA) when used as root-end filling materials. Methodology: The Cell Counting Kit-8 (CCK-8) assay was used to compare the cytotoxicity of MTA and Biodentine. Twenty-one extracted teeth with a single canal were immersed in an acidic silver nitrate solution after root-end filling. Then, the volume and depth of silver nitrate that infiltrated the apical portion of the teeth were analyzed using micro-computed tomography (micro-CT). Seventy-two roots from 3 female beagle dogs were randomly distributed into 3 groups and apical surgery was performed. After six months, the volume of the bone defect surrounding these roots was analyzed using micro-CT. Results: Based on the results of the CCK-8 assay, MTA and Biodentine did not show statistically significant differences in cytotoxicity (P>0.05). The volume and the depth of the infiltrated nitrate solution were greater in the MTA group than in the Biodentine group (P<0.05). The volume of the bone defect was larger in the MTA group than in the Biodentine group. However, the difference was not significant (P>0.05). The volumes of the bone defects in the MTA and Biodentine groups were smaller than the group without any filling materials (P<0.05). Conclusions: MTA and Biodentine exhibited comparable cellular biocompatibility. Biodentine showed a superior sealing ability to MTA in root-end filling. Both Biodentine and MTA promoted periradicular bone healing in beagle dog periradicular surgery models.

Stem Cell Marker Expression in Persistent Apical Periodontitis.

INTRODUCTION: This study evaluated the expression of CD90 (mesenchymal stem cell) and Sox2 (progenitor stem cell) markers in persistent apical periodontitis (PAP) (n = 16) and primary periapical lesions (PPLs) (n = 10). METHODS: All samples were classified histologically according to the intensity of inflammatory cell infiltrate in the periapical lesion. Immunohistochemistry was used to detect CD90 and Sox2 in PAP and PPLs. The Spearman correlation coefficient and the Mann-Whitney U test were used to analyze data at the 5% significance level. RESULTS: CD90 expression was found in mesenchymal cells and vascular endothelial cells of 68.5% of all cases of PAP. There was no correlation between CD90 expression and histopathological diagnosis (P = .053) or inflammatory cell infiltrate intensity (P = .112). CD90 staining was predominantly found in the vascular endothelial cells of 30% (n = 3) of PPLs. CD90 expression was significantly higher in PAP than in PPLs (Mann-Whitney U test, P < .05). Sox2 expression was found in all cases of PAP. Eventually, all mesenchymal and chronic inflammatory cells exhibited Sox2 expression. There was no correlation between Sox2 expression and histopathological diagnoses (P = .749), inflammatory cell infiltrate intensity (P = .510), or acute or chronic inflammatory cell infiltrate (P = .256). Sox2 expression was found in 100% of PPLs. There was no difference in Sox2 expression between PAP and PPLs (P = .477). CONCLUSIONS: Mesenchymal stem cells may contribute to the immunosuppressive environment in PAP. Additionally, distinct stem cell sources may be associated with the chronic nature of PAP as well as with the development of PPLs.

Proliferation and osteo/odontogenic differentiation of stem cells from apical papilla regulated by Zinc fingers and homeoboxes 2: An in vitro study.

In the process of tooth root development, stem cells from the apical papilla (SCAPs) can differentiate into odontoblasts and form root dentin, however, molecules regulating SCAPs differentiation have not been elucidated. Zinc fingers and homeoboxes 2 (ZHX2) is a novel transcriptional inhibitor. It is reported to modulate the development of nerve cells, liver cells, B cells, red blood cells, and so on. However, the role of ZHX2 in tooth root development remains unclear. In this study, we explored the potential role of ZHX2 in the process of SCAPs differentiation. The results showed that overexpression of ZHX2 upregulated the expression of osteo/odontogenic related genes and ALP activity, inhibited the proliferation of SCAPs. Consistently, ZHX2 knockdown reduced SCAPs mineralization and promoted SCAPs proliferation. These results indicated that ZHX2 plays a critical role in the proliferation and osteo/odontogenic differentiation of SCAPs.

Delivery of Apical Mesenchymal Stem Cells into Root Canals of Mature Teeth.

Regenerative endodontic procedures are stem cell-based treatments for immature teeth with pulp necrosis. The translation of regenerative endodontic procedures into treating mature teeth depends, among other factors, on the availability and delivery of mesenchymal stem cells (MSCs) into the root canal system. The aim of this clinical study was to evaluate whether evoked bleeding from the periapical tissues elicits the influx of MSCs into the root canal system in mature teeth with apical lesions. Participants included in this study (N = 20) were referred for endodontic treatment of mature teeth with apical lesions. Following chemomechanical debridement, intracanal bleeding from the periapical tissues was achieved, and intracanal blood samples were collected. A positive blood aspirate was also collected in the cartridges during local anesthesia. Total RNA was isolated and used as a template in quantitative reverse transcription polymerase chain reactions using MSC-specific arrays. Data were analyzed with the Wilcoxon signed-rank test, and correlation between gene expression and sex or age was tested with Spearman's rank correlation coefficient test. In addition, MSCs were isolated from an intracanal bleeding sample and subjected to flow cytometry and quantitative osteogenesis assay. Last, the presence and distribution of MSCs within periradicular lesions were evaluated with immunohistochemistry (n = 4). The MSC markers CD73, CD90, CD105, and CD146 were significantly upregulated, with median fold change values of 2.9, 31.7, 4.6, and 6.8, respectively. Conversely, the negative marker for MSCs, CD45, was significantly downregulated (median, -2.7). There was no correlation with age, sex, tooth type, or treatment for any of the evaluated genes. Isolated intracanal cells coexpressed MSC markers and demonstrated robust mineralizing differentiation potential. Finally, immunohistochemical analysis revealed that MSCs were found compartmentalized mainly within vasculature structures located in periapical lesions. Collectively, findings indicate that the evoked-bleeding technique delivers MSCs into the root canal system in mature teeth with apical lesions.

Mesenchymal stem cells as active prohealing and immunosuppressive agents in periapical environment: evidence from human and experimental periapical lesions.

INTRODUCTION: Previous studies describe contrasting molecular profiles of active and inactive periapical granulomas characterized by distinct expression of cytokines, osteoclastogenic factors, and wound healing markers. Although the molecular mechanisms underlying such a dichotomy remain unknown, in this study we investigated the potential involvement of mesenchymal stem cells (MSCs) in determining human and murine periapical lesion activity and outcomes. METHODS: Periapical granulomas (n = 83) and control samples (n = 24) were comparatively assessed for the expression levels of 11 mesenchymal stem cell (MSC) markers using real-time polymerase chain reaction. Experimental periapical lesions induced in mice were evaluated for MSC marker expression and the effects of AMD3100 treatment on lesion outcomes. RESULTS: MCS marker expression was prevalent in periapical granulomas compared with that in controls, whereas CD29, CD73, CD90, CD146, CD166, NANOG, Stro-1, and CXCR4 expressions were higher in inactive than in active lesions. Experimental periapical lesion inactivity was also associated with an increased expression of MSC markers. The inhibition of MSC mobilization to the periapex by AMD3100 resulted in increased lesion sizes; decreased expression of MSCs and wound healing markers; and increased expression of interleukin 1 beta (IL-17ß), interleukin 17 (IL-17), tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), and nuclear factor kappa-B ligand (RANKL). CONCLUSIONS: Our results show that MSC markers are overexpressed in inactive human and experimental periapical lesions and that MSC mobilization results in the attenuation of experimental lesion progression associated with immunosuppressive and prohealing mechanisms.

Periapical fluid RANKL and IL-8 are differentially regulated in pulpitis and apical periodontitis.

The dental pulp space can become infected due to a breach in the surrounding hard tissues. This leads to inflammation of the pulp (pulpitis), soft tissue breakdown, and finally to bone loss around the root apex (apical periodontitis). The succession of the molecular events leading to apical periodontitis is currently not known. The main inflammatory mediator associated with neutrophil chemotaxis is interleukin-8 (IL-8), and with bone resorption the dyad of receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG). The levels of RANKL, OPG and IL-8 were studied in periapical tissue fluid of human teeth (n = 48) diagnosed with symptomatic irreversible pulpitis (SIP) and asymptomatic apical periodontitis (AAP). SIP represents the starting point, and AAP an established steady state of the disease. Periapical tissue fluid samples were collected using paper points and then evaluated using enzyme-linked immunosorbent assays (ELISAs). Target protein levels per case were calibrated against the corresponding total protein content, as determined fluorometrically. RANKL was expressed at significantly higher levels in SIP compared to AAP (P < 0.05), whereas OPG was under the detection limit in most samples. In contrast, IL-8 levels were significantly lower in SIP compared to AAP (P < 0.05). Spearman's correlation analysis between RANKL and IL-8 revealed a significantly (P < 0.05) negative correlation between the two measures (rho = -.44). The results of this study suggest that, in the development of apical periodontitis, periapical bone resorption signaling, as determined by RANKL, occurs prior to inflammatory cell recruitment signaling, as determined by IL-8.

Cell-free approaches for dental pulp tissue engineering.

The standard treatment modality for teeth with irreversibly damaged dental pulp is root canal therapy, which involves complete removal of the soft tissue and obturation with a synthetic material. So far, research studies show that the combination of stem cells with a suitable scaffold material and transplantation into the root canal may result in the generation of pulplike tissue and the formation of tubular dentin. Because of the technical challenges associated with such a procedure, cell-free alternatives that take advantage of the dental pulp's inherent regenerative capacity because of endogenous stem cell populations and bioactive dentin matrix components need to be considered and explored. Following the tissue engineering approach, this includes (1) a bioactive scaffold, (2) growth and differentiation factors from dentin, and (3) the recruitment of stem cells from resident populations within the pulp or from the periapical region. If this concept proved to be successful, cell-free therapies may be a safer, more practical, feasible, and affordable approach to dental pulp regeneration.

Effect of dentin conditioning with intracanal medicaments on survival of stem cells of apical papilla.

INTRODUCTION: Regenerative endodontics is a valuable treatment modality for immature teeth with pulpal necrosis. A common feature in regenerative cases is the use of intracanal medicaments. Although these medicaments are chosen because of their antibacterial properties, their enduring effect on dentin (conditioning) and the subsequent impact on stem cell survival has never been evaluated. In this study, we hypothesized that triple antibiotic paste (TAP), double antibiotic paste (DAP), or Ca(OH)2 has an indirect adverse effect on the survival of stem cells of apical papilla (SCAP) by dentin conditioning. METHODS: Human dentin disks were created with a standardized root canal diameter of 3.2 mm. The disks were then exposed to either TAP or DAP (at concentrations of 1 mg/mL or 1000 mg/mL), Ca(OH)2 (Ultracal), or Hank's balanced salt solution for 7 or 28 days. Next, the medicaments were removed with copious irrigation, followed by placement of SCAP in a Matrigel scaffold in the lumen of the disks. The bioengineered constructs were cultured for 7 days, followed by determination of cellular viability by using the CellTiter-Glo luminescence assay. Data were analyzed using 1-way analysis of variance with Bonferroni post hoc test. RESULTS: Exposure of dentin to TAP or DAP at 1000 mg/mL resulted in no viable SCAP, whereas the use of these medicaments at 1 mg/mL had no adverse effect on cell viability. In contrast, Ca(OH)2 treatment significantly increased SCAP survival and proliferation when compared with the control group. CONCLUSIONS: Dentin conditioning with TAP and DAP at commonly used clinical concentration (approximately 1000 mg/mL) alters dentin in such a way as to prevent SCAP survival. This lethal indirect effect of both TAP and DAP can be largely avoided if these medicaments are used at the 1 mg/mL concentration. Conversely, dentin conditioning with Ca(OH)2 promotes SCAP survival and proliferation.

The tooth -- a treasure chest of stem cells.

Mesenchymal stem cells can be obtained with ease from dental/oral tissue, making them an attractive source of autologous stem cells. They offer a biological solution for restoring damaged dental tissues such as vital pulp engineering, regeneration of periodontal ligament lost in periodontal disease, and for generation of complete or partial tooth structures to form biological implants. Dental mesenchymal stem cells share properties with mesenchymal stem cells from bone marrow and there is a considerable potential for these cells to be used in different stem-cell-based therapies, such as bone and muscle regeneration. In addition, their immunosuppressive-immunomodulatory properties make these cells a suitable source for treating immunodisorders like systematic lupus erythematosus. In addition, gingival tissue might also be a very good source of epithelial cells used in the treatment of severe ocular surface disorders. Being such an accessible source for different stem cells, the tooth and the attached gingival tissue (usually discarded in the clinics) represent an ideal source of autologous or allogeneic stem cells that can be used in the treatment of many clinical conditions in dentistry and medicine.

Conditioned medium from periapical follicle cells induces the odontogenic differentiation of stem cells from the apical papilla in vitro.

INTRODUCTION: We investigated the biological effects of conditioned medium (CM) from periapical follicle cells (PAFCs) of root-developing tooth on the proliferation and differentiation of stem cells from the apical papilla (SCAP) in vitro. METHODS: Human SCAP and PAFCs were isolated and expanded. CM from PAFCs was prepared with the primary cells. Cell cycle analysis, methyl-thiazol-diphenyltetrazolium assay, alkaline phosphatase activity, mineralization behavior, and gene expression of odontoblast phenotype SCAP cultured with or without CM from PAFCs were evaluated. RESULTS: In the CM-treated group, the cell growth, alkaline phosphatase activity, and mineralization of SCAP were up-regulated. The expression of dentin sialophosphoprotein, alkaline phosphatase, and osteocalcin mRNA progressively increased in SCAP treated with CM from PAFCs. CONCLUSIONS: Our findings suggest that CM from PAFCs is able to provide a favorable odontogenic microenvironment to induce differentiation of SCAP along the odontoblast lineage.

Histologic evaluation and immunohistochemical localization of STRO-1 and BMP-4 in rat immature teeth: a comparison between vital and induced pulp necrosis.

OBJECTIVE: To assess histological features and the expression of STRO-1 and BMP-4 in dental pulp and periapical tissues in vital or necrotic rat immature teeth. DESIGN: The lower left first molars of male Wistar rats ageing four weeks (n=24) had their pulps exposed to the oral environment for 3, 6, 9 and 12 weeks (animals ageing 7, 10, 13 and 16 weeks-old, respectively; n=24). The right lower first molars served as control untouched teeth. After sample harvesting the jaws were dissected and processed for histology and immunodetection of STRO-1 and BMP-4. RESULTS: Necrotic teeth had root development arrested, while control animals showed development of dental tissues. Immunohistochemistry showed that detection of BMP-4 was restricted to vital pulps. For both groups, STRO-1 expression was evident around blood vessels walls. Neither BMP-4 nor STRO-1 was observed in the apical papilla region. CONCLUSION: STRO-1-positive precursor cells were not detected in the apical papilla. BMP-4 expression has not been detected during infection.

Mesenchymal stem cells from periapical lesions modulate differentiation and functional properties of monocyte-derived dendritic cells.

Immunoregulatory mechanisms within periapical lesions (PLs) are as of yet unexplored. Considering the crucial role of DCs in controlling the immune response within PLs, the immunomodulatory properties of mesenchymal stem cells (MSCs), and the colocalization of MSCs and DCs in situ, we wondered whether MSCs from PLs modulate the development and functions of DCs. Using a model of monocyte-derived DCs, we showed that PL-MSCs inhibited differentiation of DCs via soluble factors, of which IL-6 had a minor effect, but did not impair their subsequent maturation induced by pro-inflammatory cytokines. However, upon maturation such DCs favored the production of Th2/Th17 cytokines by allogenic CD4(+) lymphocytes in coculture, compared with mature DCs differentiated without PL-MSCs. PL-MSC-differentiated DCs, cultivated with pro-inflammatory cytokines and PL-MSCs, although phenotypically mature, exhibited poor allostimulatory activity, induced anergy, Th2 polarization, differentiation of suppressive CD4(+) CD25(high) CD39(+) Treg-cell subsets via IDO-1-, ILT-3-, and ILT-4-dependent mechanisms, and increased production of TGF-ß in the coculture. In contrast, DCs cultivated with PL-MSCs only during maturation stimulated proliferation and Th1 polarization of CD4(+) T cells in an IL-12-independent manner. In conclusion, PL-MSCs significantly modulate the development and functions of DCs, depending on the phase of DCs development during which the interaction occurs.

Regulation of matrix metalloproteinases, tissue inhibitor of matrix metalloproteinase-1, and extracellular metalloproteinase inducer by interleukin-17 in human periodontal ligament fibroblasts.

INTRODUCTION: Under physiological conditions, matrix metalloproteinases (MMPs) are involved in the turnover of periapical tissue, and their activity is tightly regulated by tissue inhibitors of metalloproteinases (TIMPs). Disturbances in the balance between MMPs and TIMPs may result in excessive tissue destruction. In addition, the extracellular metalloproteinase inducer (EMMPRIN) capable of inducing MMPs may also play a role in the pathologic processes. This study aimed to investigate the effects of interleukin (IL)-17 on the mRNA expression and protein production of MMP-1, MMP-2, MMP-9, MMP-13, TIMP-1, and EMMPRIN through human periodontal ligament cells. METHODS: The cells were stimulated with IL-17 (1, 10, and 50 ng/mL) for different time periods. The mRNA levels of MMP-1, MMP-2, MMP-9, MMP-13, TIMP-1, and EMMPRIN were evaluated via quantitative real-time polymerase chain reaction analysis, whereas the protein secretion into the culture medium was assessed via enzyme-linked immunosorbent assay and zymography analysis. RESULTS: IL-17 significantly up-regulated MMP-1 and MMP-13 mRNA expression but down-regulated MMP-2, MMP-9, and TIMP-1 mRNA expression. Furthermore, IL-17 (50 ng/mL) increased the secreted protein level of MMP-1 and MMP-13 and conversely reduced the level of MMP-2, MMP-9, and TIMP-1. However, IL-17 exerted no effect on EMMPRIN mRNA or protein secretion. CONCLUSIONS: This study first reported the ability of IL-17 to regulate MMP and TIMP-1 production through human periodontal ligament cells, a phenomenon that may contribute to periapical tissue destruction.

[Isolation, culture and biological characterization of Beagle stem cells from apical papilla].

OBJECTIVE: To isolate and characterize the Beagle stem cells from apical papilla. METHODS: Apical papilla was severed from the end of freshly extracted Beagle's young permanent upper anterior teeth, and digested by collagenase type I and dispase for cell culture. The isolated cells were investigated for stem cell properties by analyzing their colony-forming efficiency, growth characteristics and the expression of mesenchymal stem cell markers; and evaluating their multidifferentiation potentials including osteogenic, adipogenic, and chondrogenic potentials. Additionally, the cells were transplanted subcutaneously into immunocompromised mice to observe the mineral tissue formation. RESULTS: Our study showed that a clonogenic, rapidly proliferative population of cells existed in Beagle's apical papilla, and these cells had a significantly higher colony-forming rate than the stem cells from apical papilla derived from humans (P<0.001). These cells had multilineage differentiation ability including osteogenic, adipogenic and chondrogenic potentials. Mineralized nodules were formed after osteogenic induction, lipid droplets were found after adipogenic induction, and the pellets showed positive immunohistochemical staining for collagen II after chondrogenic induction. These cells also expressed the mesenchymal stem cell markers including STRO-1 and CD146, while negative for CK. Moreover, these cells transplanted with hydroxyapatite in immunocompromised mice could form mineral tissue and pulp-dentin complex-like tissue. CONCLUSION: There are stem cells from the apical papilla which have high proliferation ability and multilineage differentiation potential existing in the Beagle's apical papilla.

Dental stem cells for craniofacial tissue engineering.

This article focuses on the biological characterization and discussion of the potential application of oral-derived adult stem cells for craniofacial tissue engineering applications. The authors reviewed experimental (in vitro and in vivo) and clinical reports regarding the isolation, characterization, modulation, and translational clinical application of human precursor cell populations derived from postnatal dental tissues. Five different human dental stem/progenitor cell populations have been isolated and characterized. These postnatal populations present mesenchymal stem cell-like characteristics and enjoy forceful capabilities regarding the differentiation into odontogenic/osteogenic lineages, supporting evidence--in preclinical and clinical trials--for the regeneration of oral/dental tissues.

Cells isolated from inflamed periapical tissue express mesenchymal stem cell markers and are highly osteogenic.

INTRODUCTION: We previously reported the presence of mesenchymal stem/progenitor cells (MSCs) in inflamed pulp tissue. Here we asked whether MSCs also exist in inflamed periapical tissues resulting from endodontic infection. The objectives of this study were to detect the expression of MSC markers in periapical inflammatory tissues and to characterize isolated cells from these tissues. METHODS: Human periapical inflammatory tissues were collected and processed to detect MSC marker expression by immunohistochemistry. Cells were isolated and tested for cell surface marker expression by using flow cytometry and examined for multiple differentiation potential into osteogenic and adipogenic pathways. In vivo formation of mineralized tissues was assessed in a mouse model. RESULTS: Immunohistochemistry showed positive staining for MSC markers STRO-1, CD90, and CD146. Isolated cells at passage 0 appeared as typical fibroblastic cells, and a few cells formed colony-forming unit-fibroblasts (CFU-Fs). After passaging, the CFU-F forming ability diminished dramatically, and the population doubling was up to 26. Flow cytometry data showed that these cells at passage 2 expressed low levels of STRO-1 and CD146 and moderate to high levels of CD90, CD73, and CD105. At passage 6, the levels of these markers decreased. When incubated in specific differentiation medium, cells demonstrated a strong osteogenic but weak adipogenic capacity. After in vivo cell transplantation, mineralized tissues formed in immunocompromised mice. CONCLUSIONS: Human periapical inflammatory tissues expressed MSC markers, suggesting the presence of MSCs. Isolated cells exhibited typical mesenchymal cell immunophenotype with a capacity to form mineralized matrix in vitro and in vivo.