Enhancing Effects of Immobilized Chondroitin Sulfate on Odontogenic Differentiation of Dental Pulp Stem Cells and Reparative Dentin Formation

IntroductionChondroitin sulfate (CS) is a major proteoglycan involved in the mineralization of the organic matrix of dentin. In this study, the roles of CS immobilized in cross-linked collagen I (Col I) hydrogels on odontogenic differentiation of dental pulp stem cells (DPSCs) and reparative dentin formation were investigated.MethodsDifferent concentrations of CS were incorporated into the genipin–cross-linked Col I hydrogels (CS-0.05, CS-0.1, and CS-0.2, respectively). The influences of CS on the proliferation and odontogenic differentiation of DPSCs were investigated. Finally, the effect of the functionalized hydrogel on the formation of reparative dentin was analyzed in a rat pulp capping model in vivo.ResultsCS improved the proliferation of DPSCs seeded on the hydrogels (P < .05). CS also enhanced the mineralization activities and increased the expression levels of the odontogenic-related proteins of DPSCs on days 7 and 14 (P < .05). In vivo, CS-0.1 hydrogel induced reparative dentin formation with higher quality compared with mineral trioxide aggregate.ConclusionsCS immobilized in Col I hydrogels could induce odontogenic differentiation of DPSCs in vitro and promote homogeneous mineralized barrier formation in vivo. CS–Col I hydrogel has the potential for reparative dentin formation of high quality in direct pulp capping.     

Dental pulp stem cells’ secretome enhances pulp repair processes and compensates TEGDMA-induced cytotoxicity

ObjectivesAim of this study was to investigate the effects of dental pulp stem cells’ (DPSCs) secretome, expressed through their culture conditioned medium (CM), on biological endpoints related to pulp repair and on TEGDMA-induced cytotoxicity.MethodsDPSCs cultures were established and characterized for stem cell markers with flow cytometry. CM was collected from DPSCs under serum deprivation conditions (SDC) and normal serum conditions (NSC) at various time-points. CM effects on DPSCs viability, migration and mineralization potential were evaluated by MTT assay, transwell insert and in vitro scratch assay and Alizarin Red staining/quantification respectively. TEGDMA (0.25–2.0 mM) cytotoxicity regarding the same biological endpoints was tested in the presence/absence of CM. TGF-β1 and FGF-2 secretion in CM was measured by ELISA.ResultsCM collected under SDC (4 d) was able to increase cell viability by 20–25% and to reduce TEGDMA cytotoxicity by 20% (p < 0.05). CM positive effects were not obvious when collected under NSC. Transwell assay showed significant increase (26%, p < 0.05) of DPSCs’ migration after CM exposure, whereas both migration assays could not support a migration rate improvement in TEGDMA-treated cultures exposed to CM compared to TEGDMA alone. CM significantly (p < 0.01) increased DPSCs mineralization potential and completely counteracted TEGDMA cytotoxicity on this process. ELISA analysis showed a time-dependent increase of TGF-β1 and a TEGDMA concentration-dependent increase of both TGF-β1 and FGF-2 in CM.SignificanceThese findings suggest that DPSCs secretome increases their viability, migration and mineralization potential and counteracts TEGDMA-induced cytotoxicy, revealing a novel mechanism of DPSCs autocrine signaling on pulp repair processes.     

Human Freeze-dried Dentin Matrix as a Biologically Active Scaffold for Tooth Tissue Engineering

IntroductionDentin is a suitable scaffold for tooth tissue engineering and can provide the appropriate combinations and concentrations of bioactive proteins to accommodate odontogenic cells. Freeze drying is a possible strategy to treat dentin because it ensures long-term stability of biopharmaceutical products and can increase the stability of dentin for improved distribution and storage. We hypothesized that freeze-dried dentin matrix (FDDM) constitutes a novel bioinstructive scaffold for tooth tissue engineering.MethodsThis study used a modified technique to prepare an FDDM that preserved the mechanical and biological properties of dentin. The compression resistance and microhardness of FDDM were determined. Similarly, various biological characteristics, including cell morphology, cell proliferation, collagen secretion, alkaline phosphatase activity, and gene and protein expression, were investigated. To assess the inductive capacity of FDDM in vivo, FDDM and human dental pulp stem cell (DPSC) sheets were subcutaneously implanted in the dorsal pockets of nude mice. At 8 weeks postimplantation, the transplants were removed and histologically studied.ResultsThe results show that FDDM has mechanical and biological characteristics similar to those of dentin (P > .05). DPSCs cultured on FDDM and dentin showed superior attachment, growth, viability, and collagen secretion capacity but decreased mineral capability compared with DPSCs cultured with alpha minimum essential medium or hydroxyapatite (P < .05). The histologic results show that FDDM, which is similar to dentin, supported dentin/pulplike tissue regeneration in vivo as shown by the related expression levels of dentin markers, such as dentin sialoprotein and alkaline phosphatase.ConclusionsThese results suggest that FDDM constitutes a novel superior scaffold for tooth tissue engineering.     

Comparative Evaluation of the Cytotoxic and Angiogenic Effects of Minocycline and Clindamycin: An In Vitro Study

IntroductionThis study aimed to compare the cytocompatibility and angiogenic potential of 2 antibiotics (clindamycin [CLIN] and minocycline [MINO]) at distinct concentrations on dental pulp stem cells (DPSCs) and human umbilical vein endothelial cells (HUVECs).MethodsDPSCs and HUVECs were exposed to cell culture media modified with CLIN or MINO at concentrations ranging from 30 μg/mL–1000 μg/mL. Cell toxicity and proliferation were investigated using the lactate dehydrogenase and tetrazolium reduction assays, respectively. A capillarylike tube formation in vitro assay was conducted to determine the angiogenic potential associated with each antibiotic. Additionally, selected morphometric angiogenesis parameters were determined using dedicated software (WimTube; Onimagin Technologies SCA, Córdoba, Spain). All statistical analyses were performed using 1-way analysis of variance and the Tukey post hoc test (α= .05).ResultsThe collected data showed that compared with the control (cell culture media, alpha-minimum essential medium Eagle) increasing the antibiotic concentration significantly decreased cell viability and proliferation of both DPSCs and HUVECs. In terms of angiogenic potential, when tested at 30 μg/mL and 50 μg/mL, CLIN significantly amplified tube formation when compared with MINO with angiogenesis parameters (ie, tube length and tube number) similar to the effect promoted by exogenous vascular endothelial growth factor (50 ng/mL).ConclusionsCLIN was less cytotoxic when compared with MINO at higher concentrations. Of note, CLIN did not hinder the proangiogenic activity induced by vascular endothelial growth factor to the same extent as MINO, suggesting that the replacement of MINO by CLIN might translate into positive implications in the overall regenerative outcome.     

Fabrication and characterization of a novel injectable human amniotic membrane hydrogel for dentin-pulp complex regeneration

ObjectiveInjectable biomaterials that can completely fill the root canals and provide an appropriate environment will have potential application for pulp regeneration in endodontics. This study aimed to fabricate and characterize a novel injectable human amniotic membrane (HAM) hydrogel scaffold crosslinked with genipin, enabling the proliferation of Dental Pulp Stem Cells (DPSCs) and optimizing pulp regeneration.MethodsHAM extracellular matrix (ECM) hydrogels (15, 22.5, and 30 mg/ml) crosslinked with different genipin concentrations (0, 0.1, 0.5, 1, 5, and 10 mM) were evaluated for mechanical properties, tooth discoloration, cell viability, and proliferation of DPSCs. The hydrogels were subcutaneously injected in rats to assess their immunogenicity. The hydrogels were applied in a root canal model and subcutaneously implanted in rats to determine their regenerative potential for eight weeks, and histological and immunostaining analyses were performed.ResultsHydrogels crosslinked with low genipin concentration demonstrated low tooth discoloration, but 0.1 mM genipin crosslinked hydrogels were excluded due to their unfavourable mechanical properties. The degradation ratio was lower in hydrogels crosslinked with 0.5 mM genipin. The 30 mg/ml-0.5 mM crosslinked hydrogel exhibited a microporous structure, and the modulus of elasticity was 1200 PA. In vitro, cell culture showed maximum viability and proliferation in 30 mg/ml-0.5 mM crosslinked hydrogel. All groups elicited minimum immunological responses, and highly vascularized pulp-like tissue was formed in human tooth roots in both groups with/without DPSCs.SignificanceGenipin crosslinking improved the biodegradability of injectable HAM hydrogels and conferred higher biocompatibility. Hydrogels encapsulated with DPSCs can support stem cell viability and proliferation. In addition, highly vascularized pulp-like tissue formation by this biomaterial displayed potential for pulp regeneration.     

Biological Properties of Dental Pulp Stem Cells Isolated from Inflamed and Healthy Pulp and Cultured in an Inflammatory Microenvironment

IntroductionThe aim of this study was to assess whether the biological characteristics of dental pulp stem cells (DPSCs), such as viability, adhesion to dentin, mineralization, and release of immunomodulatory cytokines, are affected by the inflammatory status of the donor tissue and/or the sustained inflammatory environment.MethodsDPSCs were isolated from pulps from 3 caries-free teeth (healthy or hDPSCs), and from 3 teeth with irreversible pulpitis or deep caries (unhealthy DPSCs or uDPSCs). The cells were cultured in odontogenic and osteogenic media with or without lipopolysaccharides. Viability was analyzed by MTT assay at days 1, 3, 5, and 7; adhesion to dentin was evaluated through an environmental scanning electron microscope after 48 hours and through MTT assay; mineralization was analyzed with alizarin red staining after 21 days; and the release of proinflammatory (interleukin 6) and immunosuppressive cytokines (interleukin 10) was measured with the enzyme-linked immunosorbent assay after 24 hours and 7 days.ResultsThe inflammatory status of the pulp significantly reduced the viability and mineralization capacity of the DPSCs, although it did not affect the adhesion capacity to dentin or the secretion of the proinflammatory interleukin. The inflammatory microenvironment (lipopolysaccharide) only had a significant impact on the secretion of interleukin 6, which was augmented after 7 days.ConclusionsThe inflammatory status of the dental pulp should be taken into account when the use of DPSCs is intended either for research and/or for application in reparative or regenerative therapies.     

EphrinB2 signaling enhances osteogenic/odontogenic differentiation of human dental pulp stem cells

ObjectiveTo investigate the role of the EphrinB2 signaling pathway in the osteogenesis/odontogenesis of human dental pulp stem cells (DPSCs).DesignThe endogenous expression levels of EphrinB2 and its cognate receptors EphB2 and EphB4 in DPSCs were analyzed by qRT-PCR and Western blotting after 7, 14 and 21 days of osteogenic/odontogenic induction culture. Additionally, the phosphorylation of EphrinB2, EphB4 and ERK1/2 proteins at early time-points following osteogenic induction, were also investigated by Western blots. Subsequently, we investigated whether supplementation of recombinant EphrinB2-Fc within the induction milieu can enhance the osteogenic/odontogenic differentiation of DPSCs.ResultsEndogenous gene and protein expression levels of EphrinB2, EphB2 and EphB4 were upregulated in induced versus non-induced DPSCs, over 21 days of osteogenic/odontogenic induction. Western blots showed increase in phosphorylated EphrinB2, EphB4 and ERK1/2 proteins at early time-points following osteogenic induction. Preliminary investigation of a concentration range (0, 0.5, 1 and 2 μg/ml) of recombinant EphrinB2-Fc within osteogenic induction media, showed that 0.5 μg/ml was optimal for enhancing the osteogenic/odontogenic differentiation of DPSCs over a culture duration of 14 days. Subsequently, more comprehensive qRT-PCR analysis with 0.5 μg/ml EphrinB2-Fc revealed significant upregulation of several key osteogenic marker genes in treated versus untreated DPSCs after 21 days of osteogenic/odontogenic induction. By 7 days of osteogenic induction, DPSCs treated with 0.5 μg/ml EphrinB2-Fc exhibited significantly more calcium mineralization (Alizarin red S staining) and alkaline phosphatase activity than the untreated control.ConclusionsEphrinB2 signaling plays a key role in the osteogenic/odontogenic differentiation of DPSCs.     

Odonto/Osteogenic Differentiation of Dental Pulp Stem Cells of Type 1 Diabetic Patients with Mineral Trioxide Aggregate/1α,25-Dihydroxyvitamin D3 Combination

IntroductionVitamin D3 plays an important role in the mineralization mechanism and is often deficient in diabetic patients. The objective of this study was to investigate the odonto/osteogenic differentiation potential of the combination of mineral trioxide aggregate (MTA)/1α,25-dihydroxyvitamin D3 (VD3) on dental pulp stem cells (DPSCs) of patients with type 1 diabetes mellitus (T1DM).MethodsDPSCs isolated from donors (control and T1DM) were cultured and characterized. Cell proliferation and wound healing assays were performed. DPSCs were exposed to 4 different media: growth medium (Dulbecco's modified Eagle's medium, 10% fetal bovine serum, antibiotic, and antimycotic), differentiation medium (DM) (growth medium plus ß-glycerophosphate and ascorbic acid), DM + MTA (DM plus 0.02 mg/mL MTA), and DM + MTA + VD3 (DM + MTA and 10 nmol/L vitamin D3). Odonto/osteogenic differentiation of DPSCs was evaluated by the alizarin red test, relative real-time polymerase chain reaction (dentin sialophosphoprotein, dentin matrix protein 1, collagen type 1 alpha 1, and osteocalcin), immunocytochemistry (antibone sialoprotein II, anti–dentin matrix protein 1, and anti–collagen type 1 alpha 1), and Western blot (dentin matrix protein 1 and osteocalcin) methods.ResultsThe proliferation rates of DPSCs isolated from controls were significantly higher than DPSCs isolated from T1DM in a time-dependent manner (P < .05). Alizarin red staining and the expression of odonto/osteogenic markers showed that odonto/osteogenic differentiation was more pronounced in controls (P < .05) compared with T1DM patients. Although DM + MTA caused the odonto/osteogenic differentiation in DPSCs derived from controls, DM + MTA + VD3 resulted in the odonto/osteogenic differentiation in DPSCs of T1DM patients (P < .05).ConclusionsOdonto/osteogenic differentiation was affected by both supplements used for differentiation and the systemic disease, diabetes mellitus. The differentiation potential of T1DM-derived DPSCs was clearly increased with the VD3 supplement, although it was not as efficient as in the controls. The VD3 supplement showed a positive effect on the differentiation of T1DM DPSCs compared with MTA alone.     

Evaluation of the Apical Complex and the Coronal Pulp as a Stem Cell Source for Dentin-pulp Regeneration

IntroductionThis study compared the stemness and differentiation potential of stem cells derived from the apical complex (apical complex cells [ACCs]) and coronal pulp (dental pulp stem cells [DPSCs]) of human immature permanent teeth with the aim of determining a more suitable source of stem cells for regeneration of the dentin-pulp complex.MethodsACC and DPSC cultures were established from 13 human immature permanent teeth using the outgrowth method. The proliferation capacity and colony-forming ability of ACCs and DPSCs were evaluated. ACCs and DPSCs were analyzed for mesenchymal stem cell markers using flow cytometry. The adipogenic and osteogenic differentiation potential of ACCs and DPSCs were evaluated using the quantitative real-time polymerase chain reaction and histochemical staining. ACCs and DPSCs were transplanted subcutaneously in immunocompromised mice using macroporous biphasic calcium phosphate as a carrier. The histomorphologic characteristics of the newly formed tissues were verified using hematoxylin-eosin staining and immunohistochemical staining. Quantitative alkaline phosphatase analysis and quantitative real-time polymerase chain reaction using BSP, DSPP, POSTN, and Col XII were performed.ResultsACCs and DPSCs showed similar cell proliferation potential and colony-forming ability. The percentage of mesenchymal stem cell markers was similar between ACCs and DPSCs. In the in vitro study, ACCs and DPSCs showed adipogenic and osteogenic differentiation potential. In the in vivo study, ACCs and DPSCs formed amorphous hard tissue using macroporous biphasic calcium phosphate particles. The quantity and histomorphologic characteristics of the amorphous hard tissue were similar in the ACC and DPSC groups. Formation of periodontal ligament–like tissue, positive to Col XII, was observed in ACC transplants, which was absent in DPSC transplants.ConclusionsACCs and DPSCs showed similar stemness, proliferation rate, and hard tissue–forming capacity. The notable difference was the periodontal ligament–like fiber-forming capacity of ACCs, which indicates the presence of various lineages of stem cells in the apical complex compared with the coronal pulp. Regarding regeneration of the dentin-pulp complex, the coronal pulp can be a suitable source of stem cells considering its homogenous lineages of cells and favorable osteo/odontogenic differentiation potential.     

Micropatterned hydrogels and cell alignment enhance the odontogenic potential of stem cells from apical papilla in-vitro

IntroductionAn understanding of the extracellular matrix characteristics which stimulate and guide stem cell differentiation in the dental pulp is fundamental for the development of enhanced dental regenerative therapies. Our objectives, in this study, were to determine whether stem cells from the apical papilla (SCAP) responded to substrate stiffness, whether hydrogels providing micropatterned topographical cues stimulate SCAP self-alignment, and whether the resulting alignment could influence their differentiation towards an odontogenic lineage in-vitro.MethodsExperiments utilized gelatin methacryloyl (GelMA) hydrogels of increasing concentrations (5, 10 and 15%). We determined their compressive modulus via unconfined compression and analyzed cell spreading via F-actin/DAPI immunostaining. GelMA hydrogels were micropatterned using photolithography, in order to generate microgrooves and ridges of 60 and 120 μm, onto which SCAP were seeded and analyzed for self-alignment via fluorescence microscopy. Lastly, we analyzed the odontogenic differentiation of SCAP using alkaline phosphatase protein expression (ANOVA/Tukey α = 0.05).ResultsSCAP appeared to proliferate better on stiffer hydrogels. Both 60 and 120 μm micropatterned hydrogels guided the self-alignment of SCAP with no significant difference between them. Similarly, both 60 and 120 μm micropattern aligned cells promoted higher odontogenic differentiation than non-patterned controls.SignificanceIn summary, both substrate mechanics and geometry have a statistically significant influence on SCAP response, and may assist in the odontogenic differentiation of dental stem cells. These results may point toward the fabrication of cell-guiding scaffolds for regenerative endodontics, and may provide cues regarding the development of the pulp-dentin interface during tooth formation.     

Differential Effects of Escherichia coli– Versus Porphyromonas gingivalis–derived Lipopolysaccharides on Dental Pulp Stem Cell Differentiation in Scaffold-free Engineered Tissues

IntroductionTo leverage the therapeutic capabilities of dental pulp stem cells (DPSCs) for regenerative endodontic applications, a better understanding of their innate defense and reparative processes is needed. Lipopolysaccharide (LPS) is a major virulent factor of gram-negative bacteria and contributor to endodontic infections. We have developed 3-dimensional scaffold-free DPSC tissues that self-organize into dentin-pulp organoids comprising a mineralized dentin-like tissue on the periphery and an unmineralized pulp-like core. In this study, scaffold-free DPSC constructs were used as controllable experimental models to study the DPSC response to bacterial challenge.MethodsScaffold-free constructs were engineered using DPSCs isolated from human third molars. To simulate bacterial exposure, DPSC constructs were exposed to either Porphyromonas gingivalis–derived LPS or Escherichia coli–derived LPS. The effects of LPS on DPSC differentiation, proliferation, and apoptosis were evaluated.ResultsEngineered tissues lacking LPS treatment self-organized into dentin-pulp organoids. LPS treatment did not negatively affect DPSC proliferation or apoptosis in the engineered tissues. Both E. coli LPS and P. gingivalis LPS inhibited the up-regulation of RUNX2 messenger RNA expression and reduced the expression of the odontoblast-associated proteins (P < .05), suggesting that LPS is inhibiting odontoblastic differentiation. However, only E. coli LPS treatment significantly reduced mineral deposition in the DPSC (P < .05) constructs, indicating that E. coli LPS but not P. gingivalis LPS reduced functional differentiation of DPSCs and prevented DPSCs from self-organizing into a dentin-pulp complex–like structure.ConclusionsThis study establishes scaffold-free DPSC constructs as models of oral disease. Furthermore, it emphasizes the diversity of LPS derived from different bacterial species and highlights the necessity of using LPS derived from clinically relevant bacteria in basic science investigations.     

Dental pulp stem cells from traumatically exposed pulps exhibited an enhanced osteogenic potential and weakened odontogenic capacity

Objectives

Traumatic pulp exposure can bring about some permanent damages to tooth tissues including dental pulps. This study was designed to evaluate the effects of traumatic pulp exposure on the osteo/odontogenic capacity of dental pulp stem cells (DPSCs).

Methods

Rat incisors were artificially fractured and dental pulps were exposed to the oral environment for 48 h. Then, multi-colony-derived DPSCs from the injured pulps (iDPSCs) were isolated. Their osteo/odontogenic differentiation and the involvement of NF-κB pathway were subsequently investigated.

Results

iDPSCs presented a lower proliferative capacity than normal DPSCs (nDPSCs), as indicated by MTT and FCM assay. ALP levels in iDPSCs were significantly higher (P < 0.01) than those in nDPSCs. Alizarin red staining revealed that iDPSCs exhibited an increased capacity of calcium deposition. Moreover, iDPSCs expressed stronger osteogenic markers (Runx2/RUNX2 and Ocn/OCN) and less odontogenic gene/protein (Dspp/DSP) than nDPSCs in vitro. In vivo transplantation showed that nDPSCs implants generated the typical dentine-pulp complex while all iDPSCs pellets formed the osteodentin-like tissues which were immunopositive for OCN. Mechanistically, iDPSCs expressed the higher levels of cytoplasmic phosphorylated IκBα/P65 and nuclear P65 than nDPSCs, indicating an active cellular NF-κB pathway in iDPSCs. After the inhibition of NF-κB pathway, the osteogenic potential in iDPSCs was significantly down-regulated while odontogenic differentiation was up-regulated, as indicated by the decreased Alp/Runx2/Ocn and uprised Dspp expression.

Conclusions

Pulp exposure for 48 h decreased the odontogenic capacity and enhanced the osteogenic potential of DPSCs via the NF-κB signalling pathway.     

Mesenchymal Stem Cells Derived from Human Inflamed Dental Pulp Exhibit Impaired Immunomodulatory Capacity In Vitro

IntroductionDental pulp stem cells (DPSC) are very attractive in regenerative medicine. In this study, we focused on the characterization of the functional properties of mesenchymal stem cells derived from DPSCs. Currently, it is unknown whether inflammatory conditions present in an inflamed dental pulp tissue could alter the immunomodulatory properties of DPSCs. This study aimed to evaluate the immunomodulatory capacity in vitro of DPSCs derived from healthy and inflamed dental pulp.MethodsDPSCs from 10 healthy and inflamed dental pulps (irreversible pulpitis) were characterized according to the minimal criteria of the International Society for Cell Therapy, proliferation, differential potential, and colony-forming units. Furthermore, the immunomodulatory capacity of DPSCs was tested on the proliferation of T lymphocytes by flow cytometry and the in vitro enzyme activity of indoleamine 2, 3-dioxygenase.ResultsThere were no significant differences in the DPSC characteristics and properties such as immunophenotype, tridifferentiation, colony-forming units, and proliferation of the DPSCs derived from normal and inflamed pulp tissue. Furthermore, there were significant differences in the immunomodulatory capacity of DPSCs obtained from human healthy dental pulp and with the diagnosis of irreversible pulpitis.ConclusionsOur results showed that DPSCs isolated from inflamed dental pulp showed typical characteristics of MSCs and diminished immunosuppressive capacity in vitro in comparison with MSCs derived from healthy dental pulp. Further investigation in vivo is needed to clarify the mechanism of this diminished immunosuppressive capacity.     

外泌体诱导3D纳米纤维小管中牙髓干细胞成骨/成牙本质向分化的作用研究

目的    探究基质细胞衍生因子-1α（stromal cell-derived factor-1α,SDF-1α）诱导的根尖牙乳头干细胞来源外泌体（exosomes derived from stem cells from apical papilla,SCAP-Exo）对3D纳米纤维小管中牙髓干细胞（dental pulp stem cells,DPSCs）增殖和成骨/成牙本质向分化的影响。方法    提取SDF-1α诱导的SCAP-Exo,采用透射电镜、纳米粒子跟踪技术及Western Blot进行鉴定。将DPSCs培养于3D纳米纤维小管中,扫描电镜观察DPSCs的形态与黏附状态。使用不同质量浓度（0、50、100 μg/mL）的SCAP-Exo刺激3D纳米纤维小管中的DPSCs,分别记为对照组、50 μg/mL SCAP-Exo组和100 μg/mL SCAP-Exo组,并对细胞增殖活力和碱性磷酸酶（ALP）活性进行检测;实时RT-PCR和Western Blot分别检测成骨/成牙本质向分化相关基因的mRNA和蛋白表达水平。结果    SCAP-Exo形态呈茶托状,具有双层膜结构,平均粒径为126.4 nm,能够表达外泌体标志蛋白CD9和CD81。扫描电镜观察显示DPSCs在3D纳米纤维小管中的黏附状态良好。50 μg/mL SCAP-Exo组和100 μg/mL SCAP-Exo组DSPCs的增殖活力和ALP活性均高于对照组,且100 μg/mL SCAP-Exo组较50 μg/mL SCAP-Exo组的ALP活性升高更显著（均P < 0.05）。100 μg/mL SCAP-Exo组成骨/成牙本质向分化基因（ALP、DMP-1、BSP和OCN）的mRNA和蛋白表达水平均高于对照组（均P < 0.05）。结论    DPSCs可在3D纳米纤维小管中维持良好的增殖活力。SDF-1α诱导的SCAP-Exo可增强3D纳米纤维小管中DPSCs的增殖活力和ALP活性,以及促进其向成骨/成牙本质向分化。     

Age of the donor affects the nature of in vitro cultured human dental pulp stem cells

ObjectivesThe dental pulp stem cells (DPSCs) of six donors (three young donors aged < 19 years and three adult donors aged > 25 and < 30 years) were characterized for their stem cell marker expression and differentiation potential to study the effect of donor age on DPSCs in vitro.MethodsDPSCs were cultured in αMEM supplemented with 20% fetal calf serum (conventional conditions) or on fibronectin-coated flasks with neurobasal medium supplemented with B27, bFGF and EGF (alternative conditions). DPSCs were characterized by immunofluorescence staining to detect the neural crest/mesenchymal stem cells markers P75 and CD146, respectively. The differentiation potential was tested by the induction of DPSCs into osteogenic, adipogenic and glial lineages and then by detecting the corresponding markers osteocalcin, lipidtox and S100ß, respectively.ResultsThe DPSCs of the young donors expressed CD146 only under the conventional conditions and expressed P75 regardless of the culture conditions. However, the DPSCs of adult donors expressed CD146 only under the alternative conditions and expressed P75 only under conventional conditions. Only the DPSCs of the young donors differentiated into the glial linage. The DPSCs of the adult donors differentiated more efficiently into the adipogenic linage. Osteogenic differentiation was comparable.ConclusionDonor age affects the expression of stem cell markers and differentiation potential of DPSCs. Moreover, the effect of culture conditions on DPSCs is age dependent.     

Preliminary Study on Dental Pulp Stem Cell–mediated Pulp Regeneration in Canine Immature Permanent Teeth

IntroductionThe health of human teeth depends on the integrity of the hard tissue and the activity of the pulp and periodontal tissues, which are responsible for nutritional supply. Without the nourishing of the pulp tissue, the possibility of tooth fracture can increase. In immature permanent teeth, root development may be influenced as well. This study explored the potential of using autologous dental pulp stem cells (DPSCs) to achieve pulp regeneration in a canine pulpless model.MethodsThe establishment of the pulpless animal model involved pulp extirpation and root canal preparation of young permanent incisor teeth in beagles. Autologous DPSCs were obtained from extracted first molars and expanded ex vivo to obtain a larger number of cells. The biological characteristics of canine DPSCs (cDPSCs) were analyzed both in vitro and in vivo by using the same method as used in human DPSCs. cDPSCs were transplanted into the pulpless root canal with Gelfoam as the scaffold, and root development was evaluated by radiographic and histologic analyses.ResultscDPSCs with rapid proliferation, multiple differentiation capacity, and development potential were successfully isolated and identified both in vitro and in vivo. After they were transplanted into the pulpless root canal with Gelfoam as the scaffold, DPSCs were capable of generating pulp-like tissues containing blood vessels and dentin-like tissue. Thickening of the root canal wall was also observed.ConclusionsThis study demonstrates the feasibility of using stem cell–mediated tissue engineering to realize pulp regeneration in immature teeth.     

Adipose Tissue–derived Microvascular Fragments as Vascularization Units for Dental Pulp Regeneration

IntroductionThe transplantation of dental pulp stem cells (DPSCs) has emerged as a novel strategy for the regeneration of lost dental pulp after pulpitis and trauma. Dental pulp regeneration of the young permanent tooth with a wide tooth apical foramen has achieved significant progress in the clinical trials. However, because of the narrow apical foramen, dental pulp regeneration in adult teeth using stem cells remains difficult in the clinic. Finding out how to promote vascular reconstitution is essential for the survival of stem cells and the regeneration of dental pulp after transplantation into the adult tooth.MethodsAdipose tissue–derived microvascular fragments (ad-MVFs) were isolated from human adipose tissues. The apoptosis and senescence of DPSCs cultured in conditioned media were evaluated to explore the effects of ad-MVFs on DPSCs. DPSCs combined with ad-MVFs were inserted into the human tooth root segments and implanted subcutaneously into immunodeficient mice. Regenerated pulplike tissues were analyzed by hematoxylin and eosin and immunohistochemistry. The vessels in regenerated tissues were analyzed by Micro-CT and immunofluorescence.ResultsThe isolated ad-MVFs contained endothelial cells and pericytes. ad-MVFs effectively prevented the apoptosis and senescence of the transplanted DPSCs both in vivo and in vitro. Combined with DPSCs, ad-MVFs obviously facilitated the formation of vascular networks in the transplants. DPSCs combined with ad-MVFs formed dental pulp–like tissues with abundant cells and matrix after 4 weeks of implantation. The supplementation of ad-MVFs led to more odontoblastlike cells and increased the formation of mineralized substance around the root canal.ConclusionsCotransplantation with ad-MVFs promotes the angiogenesis and revascularization of transplanted DPSC aggregates, leading to robust regeneration of dental pulp.