Effect of low concentration of sodium fluoride on osteogenic/odontogenic differentiation of human dental pulp cells / 口腔疾病防治

Objective@#To study the effect of low concentrations of sodium fluoride on the osteogenic/odontogenic differentiation of human dental pulp cells (hDPCs) in vitro.@*Methods@#This study was reviewed and approved by the Ethics Committee. hDPCs were cultured using a modified tissue explant technique in vitro. The effects of different concentrations of sodium fluoride on the proliferation of hDPCs were measured by methylthiazol tetrazolium (MTT) assay. Appropriate concentrations were added to the osteogenic/odontogenic differentiation induction medium, and the cells were induced in vitro. Alizarin red S staining was used to detect the osteoblastic/odontogenic differentiation ability of the cells, and the mRNA expression of the key differentiation factors was detected by RT-qPCR. Moreover, the expression of key molecules of endoplasmic reticulum stress (ERS) was detected by RT-qPCR and Western blot. The data were analyzed with the SPSS 18.0 software package.@*Results@#Low concentration of NaF (0.1 mmol/L) could stimulate cell proliferation in vitro, while a high concentration (5-10 mmol/L) could inhibit cell proliferation (P<0.05). According to the literature and the experimental data, 0.1 mmol/L NaF was selected as the following experimental concentration. The levels of alizarin red S staining were increased after NaF induction of mixed osteogenic/odontogenic differentiation in vitro. The mRNA expression levels of key molecules for osteogenic/odontogenic differentiation, dentin sialophosphoprotein (DSPP), bone sialoprotein (BSP) and osteocalcin (OCN), were increased (P<0.05). The mRNA levels of ERS markers (splicing x-box binding protein-1 (sXBP1), glucose-regulated protein 78 (GRP78) and activating transcription Factor 4 (ATF4) were increased in NaF-treated cells. The protein expression levels of key ER stress molecules (phosphorylated RNA-activated protein kinase-like ER-resident kinase (p-PERK), phosphorylated eukaryotic initiation factor-2α (p-eIF2α) and ATF4) were higher in NaF-treated cells.@*Conclusion@#A low concentration of NaF promotes the osteogenic/odontogenic differentiation of hDPCs and increases the level of ER stress.

MiR⁃31 Promotes the Proliferation and Migration of Human Dental Pulp Mesenchymal Stem Cells / 中国生物化学与分子生物学报

Pulpitis and periapical inflammation are two common diseases in stomatology today. Existing treatment options primarily include root canal therapy and pulp revascularization, which can effectively control inflammation and preserve the affected tooth while also causing permanent deactivation of the pulp tissue, structural failure, and secondary infection. In recent years, research on dental pulp regeneration has progressively entered the public consciousness because of tissue engineering technology that combines stem cells and biomaterials. Due to their multi⁃differentiation and high proliferation, dental pulp stem cells (DPSCs) isolated from permanent or deciduous teeth have emerged as a significant stem cell source for dentin or pulp tissue regeneration. However, the number and survival time of live cells in the dam⁃ aged area are impacted, which significantly limits the efficacy of stem cells since they are unable to efficiently be recruited to the injured area. The ability of DPSCs to migrate and multiply must therefore be enhanced. This study sought to determine if miR⁃31 (miR⁃31) may significantly enhance the proliferative and migratory capacities of DPSCs. The tissue block enzyme digestion method was used to successfully separate and culture DPSCs from dental pulp tissues, and the miR⁃31 levels in dental pulp tissues and DPSCs from normal and inflammatory teeth were compared. The results of real⁃time fluorescence quanti⁃ tative PCR (RT⁃qPCR) revealed that the expression level of miR⁃31 in dental pulp tissues and DPSCs from inflammatory teeth was significantly lower when compared to the control group (P<0. 05). Interfer⁃ ence and over⁃expression of miR⁃31 expressions in DPSCs were specifically divided into three groups: the NC group, the miR⁃31 agomir (over⁃expressed) group and the miR⁃31 antagomir (inhibitor) group. RTq⁃PCR results showed that the transfection was successful (P<0. 001). The results of CCK⁃8, wound⁃ healing, and Transwell migration experiments showed that overexpression of miR⁃31 successfully improved the proliferation and migration abilities of DPSCs compared with the control group (P<0. 05). Further⁃ more, Western blotting analysis revealed that miR⁃31 overexpression increased the expression of important migratory proteins, including CXC chemokine receptor type 4 (CXCR4) and matrix metalloproteinase2 (MMP2), as well as key proliferation proteins Ki67 and proliferating cell nuclear antigen (PCNA) (P< 0. 05). This study demonstrates that miR⁃31 can effectively boost the proliferation and migratory ability of DPSCs, providing strong theoretical support for the increased use of DPSCs in regenerative medicine.

LED red light up-regulates MAPK signal to promote osteogenic/odontogenic differentiation of human dental pulp stem cells in an inflammatory environment / 口腔疾病防治

Objective @#To study the effect of light-emitting diode (LED) red light on the osteogenic/odontogenic differentiation of human dental pulp stem cells (hDPSCs) and its mechanism were discussed. @*Methods@#This study has been reviewed and approved by the Ethics Committee. hDPSCs were cultured by tissue block enzyme digestion. The proliferative capacity of hDPSCs was detected by the CCK-8 at days 1, 3, 5 and 7 under stimulation with 0, 1, 5 and 10 μg/mL lipopolysaccharide (LPS), and the LPS stimulatory concentration was screened. The CG group (mineralization induction), LPS+CG group, and LPS+CG+ (2, 4, 6, 8, and 10 J/cm2) LED red light groups were set. On day 7, alkaline phosphatase (ALP) staining and ALP activity were determined. Relative expression levels of the ALP, osterix (OSX), dentin matrix protein-1 (DMP-1) and dentin sialophosphoprotein (DSPP) genes were measured by qRT-PCR. On day 21, alizarin red staining and calcium nodule quantitative determination were performed to screen the best light energy. The LPS+CG group and LPS+CG+LED group (optimal energy) were set up, and the secretion and expression levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were detected by ELISAs on days 1, 3, 5 and 7. The relative expression levels of the extracellular regulated protein kinases 1/2 (ERK1/2), p38, c-Jun N-terminal kinase (JNK), and extracellular regulated protein kinases 5 (ERK5) proteins and their phosphorylated proteins in the MAPK signaling pathway were detected by Western blots. After the pathway was blocked, the relative expression levels of the ALP, OSX, DMP-1, and DSPP proteins after LED red light irradiation on day 7 were detected by Western blots.@*Results@# CCK-8 assays showed that the proliferation of hDPSCs induced by 10 μg/mL LPS was lower than that of the 0, 1, and 5 μg/mL groups on the 5th and 7th days (P<0.05), and 10 μg/mL was selected as the LPS stimulatory concentration in the follow-up experiment. ALP staining, ALP activity, gene expression levels of ALP, OSX, DMP-1 and DSPP and calcium nodule quantification in the LPS+CG+4 J/cm2 group were higher than those in the other treatment groups (P<0.05). 4 J/cm2 LED red light had the strongest ability to promote osteogenic/odontogenic differentiation and was used as the LED light energy density in subsequent experiments. ELISA showed that the secretion and expression levels of TNF-α and IL-1β in the LPS+CG+LED group were lower than those in the LPS+CG group on the 5th and 7th days (P<0.05). Western blot analysis showed that 4 J/cm2 LED red light promoted the expression levels of the p-ERK1/2, p-p38, p-JNK and p-ERK5 proteins. After the MAPK pathway was blocked, the expression levels of the ALP, OSX, DMP-1, and DSPP proteins in the LPS+CG+LED+U0126 (ERK1/2 inhibitor), SP600125 (JNK inhibitor), and BIX02189 (ERK5 inhibitor) groups were lower than those in the LPS+CG+LED group (P<0.001). The protein expression levels of ALP, OSX and DMP-1 in the LPS+CG+LED+SB203580 (p38 inhibitor) group were not significantly different from those in the LPS+CG+LED group (P>0.05).@*Conclusion@#In inflammatory conditions, LED red light promotes osteogenic/odontogenic differentiation of hDPSCs. This effect may be attributed to enhancement of the ERK1/2, JNK, and ERK5 signaling pathways, which reduces the production of the inflammatory cytokines TNF-α and IL-1β.

Study of endoplasmic reticulum stress in human dental pulp cells induced by oxygen-glucose deprivation culture in vitro / 口腔疾病防治

Objective@#Oxygen-glucose deprivation (OGD) is used to mimic ischemia in vitro to observe whether endoplasmic reticulum (ER) stress is involved in human dental pulp cells (hDPCs) after OGD and to better understand the regulatory mechanism of hDPCs in ischemia.@*Methods@# hDPCs were cultured in glucose-free DMEM and hypoxia (volume fraction 2% O2) to establish an hDPCs OGD model in vitro, which mimics hDPCs ischemia in vitro. hDPCs were divided into a control group (normal culture) and an experimental group (OGD 0 h, 2 h, 4 h and 8 h groups). After pretreatment with OGD for 0, 2, 4 and 8 h, hDPC viability was measured by methylthiazol tetrazolium (MTT) assay. qRT-PCR was used to detect the mRNA expression of ER stress markers [splicing x-box binding protein1 (sXBP1), activating transcription Factor 4 (ATF4) and C/EBP homologous protein (chop)]. Western blot was used to detect the protein expression of ER stress markers [phosphorylated RNA-activated protein kinase-like ER-resident kinase (p-perk) and phosphorylated eukaryotic initiation factor-2α (p-eIF2α)]. @*Results@#Compared with OGD 0 h group, cell viability of hDPCs decreased when exposed to OGD treatment for 2 h, 4 h and 8 h. Compared with the control group, mRNA expressions of ER stress makers (sXBP1, ATF4 and chop) and the protein expressions of ER stress protein markers (p-perk andp-eIF2α) increased in OGD treatment cells after 4 h were higher in OGD cells. The differences were statistically significant (P<0.05).@*Conclusion@#The results indicate that ER stress response is involved in hDPCs in OGD treatment.

Effect of lncRNA TUG1 on osteogenic/odontogenic differentiation of human dental pulp stem cells / 口腔疾病防治

Objective@#To explore the effects of long noncoding-RNA (lncRNA) taurine upregulated gene 1 (TUG1) on the proliferation and osteogenic/odontoblast differentiation of human dental pulp stem cells (hDPSCs). @*Methods @# hDPSCs were isolated and cultured. The surface antigens CD44, CD45, CD73, CD90, CD133 and STRO-1 were detected by flow cytometry. Alkaline phosphatase (ALP) staining and alizarin red staining were used to identify the ability of cells to differentiate. RNA was collected on Days 0, 7 and 14 of the osteogenic induction of hDPSCs, and qRT-PCR was used to detect the relative expression of TUG1. The hDPSCs were stably transfected with a lentiviral vector containing the TUG1-silenced pSLenti-U6-shRNA(TUG1)-CMV-EGFP-F2A-Puro-WPRE to silence TUG1. The ability of hDPSCs to proliferate was assessed with the CCK-8 method. ALP and alizarin red staining and quantitative detection were used to detect the ALP activity and formation of mineralized nodules of hDPSCs. The expression levels of dentin sialophosphoprotein (DSPP), dentin matrix protein-1 (DMP-1), Runt-associated transcription factor 2 (Runx2), osteocalcin (OCN) and osteopontin (OPN) genes and proteins were measured by qRT-PCR and Western blot.@*Results @#The hDPSCs were successfully isolated and cultured, and TUG1 expression was significantly increased during osteogenic differentiation (P<0.05). The hDPSCs proliferation was suppressed after silencing TUG1(P<0.05). After osteogenic induction, ALP and alizarin red staining showed that ALP activity and mineralized nodules were suppressed by silencing TUG1. The expression levels of the odontogenic differentiation gene DSPP and DMP-1 and the osteogenic differentiation gene Runx2, OCN and OPN were also significantly decreased (P<0.05).@*Conclusion @# Knocking down TUG1 can inhibit the proliferation and osteogenic/odontogenic differentiation of hDPSCs.

Influence of photobiomodulation and tricalcium silicate-based cement on viability and dentinogenic activity of cultured human dental pulp stem cells / Influência da fotobiomodulação e cimento de silicato tricálcio na viabilidade e atividade dentinogênica de células tronco cultivadas da polpa de dente humano

Objective: To assess the effect of application of Biodentine (BD), Photobiomodulation (PBM) using 810 nm diode laser and both on the proliferation and odontogenic differentiation of human dental pulp stem cells (HDPSCs). Material and Methods: HDPSCs were collected, isolated, and characterized and then divided into six groups: groups 1, control; groups 2, biodentine (BD); group 3, irradiation at 1 J/cm 2 of 810-nm diode laser; group 4, irradiation at 1 J/cm 2 and culture with BD; group 5, irradiation at 2 J/cm 2, and group 6, irradiation at 2 J/cm 2 and culture with BD. Viability assay was measured through MTT assay and Alkaline phosphatase (ALP) enzyme activity and mRNA levels of RUNX2, collagen 1 (Col-1) and BMP2 were also assessed. Results: Photobiomodulation at 1 and 2 J/cm 2 combined with biodentine significantly promoted HDPSCs proliferation (in MTT assay results) and odontogenic differentiation (through the gene expression of RUNX2, Col-1 and BMP2 levels (p < 0.05). Conclusion: Photobiomodulation at 2 J/cm 2 combined with biodentine enhanced proliferation and odontogenic differentiation of cultured HDPSCs and thus could further be beneficial for dentin regeneration (AU)

Objetivo: Avaliar o efeito da aplicação de Biodentina (BD), Fotobiomodulação (PBM) usando diodo de laser de 810 nm e ambos na proliferação e diferenciação odontogênica de células tronco cultivadas da polpa dental (HDPSCs). Material e Métodos: HDPSCs foram coletadas, isoladas, caracterizadas e então divididas em seis grupos: grupo 1, controle; grupo 2, biodentina (BD); grupo 3, irradiação com diodo de laser a 1 J/cm2 de 810- nm; grupo 4, irradiação a 1 J/cm 2 e cultivo com BD; grupo 5, irradiação a 2 J/cm2, e grupo 6, irradiação a 2 J/cm2 e cultivo com BD. A viabilidade foi mensurada através do teste MTT e a atividade da enzima Fosfatase alcalina (ALP), e níveis de RNAm de RUNX2, de colágeno 1 (Col-1) e de BMP2 foram também mensurados. Resultados: Fotobiomodulação a 1 e 2 J/cm 2 combinada com biodentina promoveu significativa proliferação de HDPSCs (nos resultados do teste MTT) e diferenciação odontogênica (através da expressão genética dos níveis de RUNX2, Col-1 e BMP2 (p < 0.05)). Conclusão: Fotobiomodulação a 2 J/cm2 combinada com biodentina aumentou a proliferação e diferenciação odontogênica de HDPSCs cultivadas e dessa forma poderia ser benéfica para a regeneração dentinária. (AU)

Odontogenic gene expression profile of human dental pulp-derived cells under high glucose influence: a microarray analysis

Abstract Hyperglycemia, a major characteristic of diabetes, is considered to play a vital role in diabetic complications. High glucose levels have been found to inhibit the mineralization of dental pulp cells. However, gene expression associated with this phenomenon has not yet been reported. This is important for future dental therapeutic application. Objective Our study aimed to investigate the effect of high glucose levels on mineralization of human dental pulp-derived cells (hDPCs) and identify the genes involved. Methodology hDPCs were cultured in mineralizing medium containing 25 or 5.5 mM D-glucose. On days 1 and 14, RNA was extracted and expression microarray performed. Then, differentially expressed genes (DEGs) were selected for further validation using the reverse transcription quantitative polymerase chain reaction (RT-qPCR) method. Cells were fixed and stained with alizarin red on day 21 to detect the formation of mineralized nodules, which was further quantified by acetic acid extraction. Results Comparisons between high-glucose and low-glucose conditions showed that on day 1, there were 72 significantly up-regulated and 75 down-regulated genes in the high-glucose condition. Moreover, 115 significantly up- and 292 down-regulated genes were identified in the high-glucose condition on day 14. DEGs were enriched in different GO terms and pathways, such as biological and cellular processes, metabolic pathways, cytokine-cytokine receptor interaction and AGE-RAGE signaling pathways. RT-qPCR results confirmed the significant expression of pyruvate dehydrogenase kinase 3 (PDK3), cyclin-dependent kinase 8 (CDK8), activating transcription factor 3 (ATF3), fibulin-7 (Fbln-7), hyaluronan synthase 1 (HAS1), interleukin 4 receptor (IL-4R) and apolipoprotein C1 (ApoC1). Conclusions The high-glucose condition significantly inhibited the mineralization of hDPCs. DEGs were identified, and interestingly, HAS1 and Fbln-7 genes may be involved in the glucose inhibitory effect on hDPC mineralization.

High glucose affects proliferation, reactive oxygen species and mineralization of human dental pulp cells

Abstract Diabetes is a group of metabolic disorders that can lead to damage and dysfunction of many organs including the dental pulp. Increased inflammatory response, reduction of dentin formation and impaired healing were reported in diabetic dental pulp. Hyperglycemia, which is a main characteristic of diabetes, was suggested to play a role in many diabetic complications. Therefore our aim was to investigate the effects of high glucose levels on proliferation, reactive oxygen species (ROS) production and odontogenic differentiation of human dental pulp cells (HDPCs). HDPCs were cultured under low glucose (5.5mM Glucose), high glucose (25 mM Glucose) and mannitol (iso-osmolar control) conditions. Cell proliferation was analyzed by MTT assay for 11 days. Glutathione and DCFH-DA assay were used to assess ROS and antioxidant levels after 24 h of glucose exposure. Odontogenic differentiation was evaluated and quantified by alizarin red staining on day 21. Expression of mineralization-associated genes, which were alkaline phosphatase, dentin sialophosphoprotein and osteonectin, was determined by RT-qPCR on day 14. The results showed that high glucose concentration decreased proliferation of HDPCs. Odontogenic differentiation, both by gene expression and mineral matrix deposit, was inhibited by high glucose condition. In addition, high DCF levels and low reduced glutathione levels were observed in high glucose condition. However, no differences were observed between mannitol and low glucose conditions. In conclusion, the results clearly showed the negative effect of high glucose condition on HDPCs proliferation and differentiation. Moreover, it also induced ROS production of HDPCs.

Resumo O diabetes abrange um grupo de distúrbios metabólicos que podem levar a danos e disfunções de muitos órgãos, incluindo a polpa dentária. Aumento da resposta inflamatória, redução da formação de dentina e comprometimento da cicatrização foram relatados na polpa dentária diabética. A hiperglicemia, que é uma característica determinante do diabetes, desempenha um papel importante em muitas complicações diabéticas. Portanto, nosso objetivo foi investigar os efeitos dos altos níveis de glicose na proliferação, produção de espécies reativas de oxigênio (ROS, em inglês) e diferenciação odontogênica das células da polpa dental humana (HDPCs, em inglês). As HDPCs foram cultivadas em condições de baixa glicose (glicose 5,5 mM), alta glicose (glicose 25 mM) e manitol (controle iso-osmolar). A proliferação celular foi analisada pelo ensaio MTT por 11 dias. Glutationa e DCFH-DA foram utilizados para avaliar os níveis de ROS e antioxidantes após 24 h de exposição à glicose. A diferenciação odontogênica foi avaliada e quantificada pela coloração com vermelho de alizarina no dia 21. A expressão de genes associados à mineralização, que eram fosfatase alcalina, sialofosfoproteína de dentina e osteonectina, foi determinada por RT-qPCR no dia 14. Os resultados mostraram que a alta concentração de glicose diminuiu a proliferação de HDPCs. A diferenciação odontogênica, tanto pela expressão gênica quanto pelo depósito da matriz mineral, foi inibida pela condição de alta glicose. Além disso, altos níveis de DCF e níveis reduzidos de glutationa foram observados na condição de alta glicose. No entanto, não foram observadas diferenças entre o manitol e as condições de baixa glicose. Em conclusão, os resultados mostraram claramente o efeito negativo da condição de alta glicose na proliferação e diferenciação de HDPCs. Além disso, essa condição também induziu a produção de ROS em HDPCs.

Non-coding rnas in human dental pulp stem cells: Regulations and mechanisms / 中国组织工程研究

BACKGROUND: Human dental pulp stem cells are important oral mesenchymal stem cells with strongproliferation and multidirectional differentiation functions. In-depth studies on the Human Genome Project make people gradually reali ze that functional non-coding RNAs play an extraordinary role in regulating gene expression. OBJECTIVE: To discuss the function and application of non-coding RNAs in human dental pulp stem cells. METHODS: Using “ncRNAs, human dental pulp stem cells, regenerative medicine” as keywords in English and Chinese, the first author searched PubMed, Medline, CNKI, and WanFang for relevant articles published from 2005 to 2019. Literatures unrelated to the purpose of the study and repetitive literatures were excluded, and 71 articles that meet the criteria were included for review. RESULTS AND CONCLUSION: It is now generally believed that non-coding RNAs can be used as a signal of specific cell state, providing prognostic value and even providing treatment options for patients. With the continuous development of regenerative medicine applications, human dental pulp stem cells are arousing increasing attentions. Exploration on the relationship between non-coding RNAs and human dental pulp stem cells provides a new approach for the clinical application of human dental pulp stem cells.

Changes in the proliferation and angiogenesis of human dental pulp stem cells after treated with prostaglandin E1 combined with basic fibroblast growth factor / 中国组织工程研究

BACKGROUND: Prostaglandin E1 and basic fibroblast growth factor can promote the proliferation of human dental pulp stem cells, but the effects of their combinations on the proliferation of human dental pulp stem cells and angiogenesis are unknown. OBJECTIVE: To investigate the effects of prostaglandin E1 combined with basic fibroblast growth factor on the proliferation and angiogenesis of human dental pulp stem cells. METHODS: (1) Human dental pulp stem cells were isolated and cultured in vitro. After detection and identification of surface markers, prostaglandin E1 and basic fibroblast growth factor at concentrations of 5, 10, 20, 50 and 100 μg/L were used to treat human dental pulp stem cells in vitro. The untreated cells served as control group. The cell proliferation was detected by cell counting kit-8 assay, and the optimum drug concentration and time of drug action were screened. (2) The in vitro cultured human dental pulp stem cells were divided into four groups: blank control group, prostaglandin E1 group, basic fibroblast growth factor group and combination group. The cell proliferation was detected by cell counting kit-8 assay. Human dental pulp stem cell conditioned medium was extracted. The levels of vascular endothelial growth factor and endostatin in the culture medium were detected by ELISA. The in vitro tubular formation ability of human umbilical vein endothelial cells after culture in conditioned medium was tested by tubule formation experiment. RESULTS AND CONCLUSION: The optimum concentration of prostaglandin E1 and basic fibroblast growth factor was 20 μg/L, and the optimum time of action was 2 days. Compared with the blank control group, the relative proliferation rate, level of vascular endothelial growth factor and the angiogenesis ability of human umbilical vein endothelial cell in vitro in the prostaglandin E1, basic fibroblast growth factor and combination groups were significantly increased (P < 0.05), while the level of endostatin was significantly decreased (P < 0.05). All above index levels in the combination group were significantly superior to those in the prostaglandin E1 and basic fibroblast growth factor groups (P < 0.05). In summary, prostaglandin E1 combined with basic fibroblast growth factor can promote the proliferation of human dental pulp stem cells and enhance the tubular formation ability of human umbilical vein endothelial cells in vitro.

Regulation of Wnt signaling pathway on calcium hydroxide-promoted osteogenic differentiation of hDPSCs / 国际生物医学工程杂志

Objective To investigate the role of Wnt/β-catenin signaling pathway in the osteogenic differentiation of human dental pulp stem cells (hDPSCs). Methods After 14 days of the calcium hydroxide training, the cytoskeletal changes of hDPSCs, the expression of β-catenin, i.e. the key promoter of in the Wnt signaling pathway, and the cell localization were detected by laser scanning confocal technique. The Wnt signaling pathways were up-regulated and inhibited, and the osteogenic differentiation and mineralization of hDPSCs were detected by Western Blot and alizarin red staining after 14 days of the training. Results The cytoskeleton of hDPSCs was rearranged by the effect of calcium hydroxide, and theβ-catenin migration from nucleus to cytoplasm were observed. The number of calcium nodules in hDPSCs was decreased after blocking Wnt signaling pathway by Dickkopf-related protein 1 (DKK-1). The calcium hydroxide treatment can promoted dentin sialophosphoprotein (DSPP) expression in hDPSCs. Conclusions Calcium hydroxide can down-regulate the expression of canonical Wnt signaling pathway and promote osteogenic differentiation and mineralization and odontogenetic differentiation of hDPSCs.

A Comparison of the Effects of Silica and Hydroxyapatite Nanoparticles on Poly(ε-caprolactone)-Poly(ethylene glycol)-Poly(ε-caprolactone)/Chitosan Nanofibrous Scaffolds for Bone Tissue Engineering

BACKGROUND: The major challenge of tissue engineering is to develop constructions with suitable properties which would mimic the natural extracellular matrix to induce the proliferation and differentiation of cells. Poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL, PCEC), chitosan (CS), nano-silica (n-SiO₂) and nano-hydroxyapatite (n-HA) are biomaterials successfully applied for the preparation of 3D structures appropriate for tissue engineering. METHODS: We evaluated the effect of n-HA and n-SiO₂ incorporated PCEC-CS nanofibers on physical properties and osteogenic differentiation of human dental pulp stem cells (hDPSCs). Fourier transform infrared spectroscopy, field emission scanning electron microscope, transmission electron microscope, thermogravimetric analysis, contact angle and mechanical test were applied to evaluate the physicochemical properties of nanofibers. Cell adhesion and proliferation of hDPSCs and their osteoblastic differentiation on nanofibers were assessed using MTT assay, DAPI staining, alizarin red S staining, and QRT-PCR assay. RESULTS: All the samples demonstrated bead-less morphologies with an average diameter in the range of 190–260 nm. The mechanical test studies showed that scaffolds incorporated with n-HA had a higher tensile strength than ones incorporated with n-SiO₂. While the hydrophilicity of n-SiO₂ incorporated PCEC-CS nanofibers was higher than that of samples enriched with n-HA. Cell adhesion and proliferation studies showed that n-HA incorporated nanofibers were slightly superior to n-SiO₂ incorporated ones. Alizarin red S staining and QRT-PCR analysis confirmed the osteogenic differentiation of hDPSCs on PCEC-CS nanofibers incorporated with n-HA and n-SiO₂. CONCLUSION: Compared to other groups, PCEC-CS nanofibers incorporated with 15 wt% n-HA were able to support more cell adhesion and differentiation, thus are better candidates for bone tissue engineering applications.

Effects of triethylene glycol dimethacrylate (TEGDMA) on the odontoclastic differentiation ability of human dental pulp cells

Abstract Objectives: The primary purpose of this study was to examine the effects of triethylene glycol dimethacrylate (TEGDMA) on odontoclastic differentiation in the dental pulp tissue. Material and Methods: The effects of different TEGDMA dosages on the odontoclastic differentiation capability of dental pulp cells were analyzed in vitro using the following methodologies: i) flow cytometry and tartrate-resistant acid phosphatase (TRAP) staining; ii) apoptotic effects using Annexin V staining; iii) mRNA expression of osteoprotegerin (OPG) and receptor activator of nuclear factor (NF)-kB ligand (RANKL) genes by quantitative Real-time PCR (qRT-PCR); and iv) OPG and RANKL protein expression by enzyme-linked immunosorbent assay (ELISA). Results: TEGDMA caused relatively less odontoclastic differentiation in comparison with the control group; however, odontoclastic differentiation augmented with increasing doses of TEGDMA (p<0.05). The mRNA and protein expression of OPG was lower in TEGDMA treated pulp cells than in the control group (p<0.05). While the mRNA expression of RANKL remained unchanged compared to the control group (p>0.05), its protein expression was higher than the control group (p<0.05). In addition, TEGDMA increased the apoptosis of dental pulp cells dose dependently. Conclusions: TEGDMA reduced the odontoclastic differentiation ability of human dental pulp cells. However, odontoclastic differentiation ratios increased proportionally with the increasing dose of TEGDMA.

Induction of Prostaglandin E₂ by Porphyromonas gingivalis in Human Dental Pulp Cells

Cyclooxygenase-2 (COX-2)-mediated prostaglandin E₂ (PGE₂) plays a key role in development and progression of inflammatory responses and Porphyromonas gingivalis is a common endodontic pathogen. In this study, we investigated induction of COX-2 and PGE₂ by P. gingivalis in human dental pulp cells (HDPCs). P. gingivalis increased expression of COX-2, but not that of COX-1. Increased levels of PGE₂ were released from P. gingivalis-infected HDPCs and this PGE₂ increase was blocked by celecoxib, a selective COX-2 inhibitor. P. gingivalis activated all three types of mitogen-activated protein kinases (MAPKs). P. gingivalis-induced activation of nuclear factor-κB (NF-κB) was demonstrated by the results of phosphorylation of NF-κ B p65 and degradation of inhibitor of κB-α (IκB-α). Pharmacological inhibition of each of the three types of MAPKs and NF-κB substantially attenuated P. gingivalis induced PGE2 production. These results suggest that P. gingivalis should promote endodontic inflammation by stimulating dental pulp cells to produce PGE₂.

Melatonin Rescues Human Dental Pulp Cells from Premature Senescence Induced by H₂O₂

Although anti-aging activities of melatonin, a hormone secreted by the pineal gland, have been reported in senescence-accelerated mouse models and several types of cells, its impact and mechanism on the senescence of human dental pulp cells (HDPCs) remains unknown. In this study, we examined the impact of melatonin on cellular premature senescence of HDPCs. Here, we found that melatonin markedly inhibited senescent characteristics of HDPCs after exposure to hydrogen peroxide (H₂O₂), including the increase in senescence-associated β-galactosidase (SA-β-gal)-positive HDPCs and the upregulation of p21 protein, an indicator for senescence. In addition, as melatonin attenuated H₂O₂-stimulated phosphorylation of c-Jun N-terminal kinase (JNK), while selective inhibition of JNK activity with SP600125 significantly attenuated H₂O₂-induced increase in SA-beta-gal activity. Results reveal that melatonin antagonizes premature senescence of HDPCs via JNK pathway. Thus, melatonin may have therapeutic potential to prevent stress-induced premature senescence, possibly correlated with development of dental pulp diseases, and to maintain oral health across the life span.

Research progress on applications of hDPSCs in cornea reconstruction / 国际眼科杂志(Guoji Yanke Zazhi)

The corneal reconstruction is tosurgial recover the structure integrity and corneal function after suffered from various trauma, inflammation and degenerative diseases.The corneal diseases caused millions of people worldwide suffering from eyesight damages and even blindness.At present, the corneal transplant is the main therapy for corneal blindness.However, the shortage in donor corneal issue is a worldwide problem and the failure due to the immunologic rejection of host is common.Nowadays, with the development of tissue culture and bioengineering technology, the application prospect of autologous stem cell transplantation is becoming more and more popular which might replace the allogeneic transplantation, becoming an important clinical treatment of regenerative medicine.Human dental pulp stem cells (hDPSCs) is a class of adult stem cell divided from the third molar teeth.Both hDPSCs and corneal cell are from the cranial nerve in embryonic ectoderm.Extensive researches show that the hDPSCs have the potentialities in corneal cell differentiation without causing immunologic rejection of the recipient.These findings manifested the potentials of hDPSCs in the clinical applications related to ocular surface reconstruction.In this paper, the features and current investigation status of hDPSCs in ocular surface reconstruction are reviewed.

The effects of human dental pulp stem cells-conditioned medium on the osteogenic differentiation of human dental follicle stem cells in vitro / 实用口腔医学杂志

Objective:To evaluate the effects of human dental pulp stem cells-conditioned medium(HDPSCs-CM)on the osteogenic differentiation of human dental follicle stem cells(HDFSCs) in vitro.Methods:HDFSCs were in vitro cultured,purified and identified.CCK-8 assay was applied to evaluate the HDFSCs viability after 7 days cultured by HDPSCs-CM;the morphological changes of HDFSCs were observed;the osteogenic differentiation was studied by alkaline phosphatase(ALP) staining and alizarin red staining.The mRNA expression of POSTN,Col-Ⅰ,ALP,BSP and OPN was detected by Real-Time PCR.Results:Induced by HDPSCs-CM,HDFSCs exhibited several characteristics of cementoblast or osteoblast lineages.In the induction group the viability of HDFSCs was inhibited(P<0.05 or P<0.01),ALP staining was stronger and there were more mineralized nodules,the expression levels of POSTN,Col-Ⅰ,ALP,BSP and OPN were upregulated(P<0.05 or P<0.01).Conclusion:HDPSCs-CM can promote the osteogenic differentiation of HDFSCs.

Effects of lipopolysaccharide on proliferation, differentiation and apoptosis of human dental pulp stem cells by Notch signaling pathway / 中国免疫学杂志

Objective:To investigate the effects and its mechanism of lipopolysaccharide on the proliferation,differentiation and apoptosis of human dental pulp stem cells by Notch signaling pathway. Methods:Human dental pulp stem cells( hDPSCs) was isolated from dental pulp tissue;cell proliferation was detected after 0,0. 1,1,10 μg/ml treated cells for 1,3,5,7 days by CCK8 test;related mRNA expression ALP,DSPP,DMP1 gene was detected after 1 μg/ml lipopolysaccharide treated hDPSCs for 0,3,7,14,21 day by RT-PCR;cell apoptosis was detected after 1 μg/ml lipopolysaccharide treated hDPSCs for 0,7,14,21 day by flow cytometry. Cleaved caspase3,Notch1,Hes1 protein expression was detected by Western blot. Results:Cell proliferation after different concentrations lipopo-lysaccharide stimulated hDPSCs for 1, 3, 5 days had no significant difference, significantly lower at 7 day than 0 μg/ml lipopolysaccharide group(P<0. 01). ALP,DSPP,DMP1 mRNA expression lipopolysaccharide treated hDPSCs at 3 day compared with the control group had no statistical significance(P>0. 05),significantly higher at 7,14,21 day than control group(P<0. 01);cells apoptosis rate and Cleaved caspase3,Notch1,Hes1 protein expression lipopolysaccharide treatment hDPSCs at 7,14 and 21day was sig-nificantly higher than the control group(P<0. 01);ALP,DSPP,DMP1 mRNA expression and apoptosis rate and Cleaved caspase3, Notch1,Hes1 protein expression at 21 day was a downward trend. Conclusion:Lipopolysaccharide can decrease the proliferation of hDPSCs and promote its mineralization and apoptosis,which may be related to the activation of Notch signaling pathway.

Effects of lipopolysaccharide on proliferation, differentiation and apoptosis of human dental pulp stem cells by Notch signaling pathway / 中国免疫学杂志

Objective:To investigate the effects and its mechanism of lipopolysaccharide on the proliferation,differentiation and apoptosis of human dental pulp stem cells by Notch signaling pathway. Methods:Human dental pulp stem cells( hDPSCs) was isolated from dental pulp tissue;cell proliferation was detected after 0,0. 1,1,10 μg/ml treated cells for 1,3,5,7 days by CCK8 test;related mRNA expression ALP,DSPP,DMP1 gene was detected after 1 μg/ml lipopolysaccharide treated hDPSCs for 0,3,7,14,21 day by RT-PCR;cell apoptosis was detected after 1 μg/ml lipopolysaccharide treated hDPSCs for 0,7,14,21 day by flow cytometry. Cleaved caspase3,Notch1,Hes1 protein expression was detected by Western blot. Results:Cell proliferation after different concentrations lipopo-lysaccharide stimulated hDPSCs for 1, 3, 5 days had no significant difference, significantly lower at 7 day than 0 μg/ml lipopolysaccharide group(P<0. 01). ALP,DSPP,DMP1 mRNA expression lipopolysaccharide treated hDPSCs at 3 day compared with the control group had no statistical significance(P>0. 05),significantly higher at 7,14,21 day than control group(P<0. 01);cells apoptosis rate and Cleaved caspase3,Notch1,Hes1 protein expression lipopolysaccharide treatment hDPSCs at 7,14 and 21day was sig-nificantly higher than the control group(P<0. 01);ALP,DSPP,DMP1 mRNA expression and apoptosis rate and Cleaved caspase3, Notch1,Hes1 protein expression at 21 day was a downward trend. Conclusion:Lipopolysaccharide can decrease the proliferation of hDPSCs and promote its mineralization and apoptosis,which may be related to the activation of Notch signaling pathway.

Effect of hypoxia on angiogenesis-related proteins in human dental pulp cells

Dental pulp is a highly vascularized tissue with high regenerative potential. Revascularization of severed vasculature in the tooth is required for pulp healing during avulsed tooth treatment. In this study, the relative expression of angiogenesis-related proteins was determined in human dental pulp cells using a human angiogenesis proteome profiler array. The proteome profiler array detected differentially expressed angiogenesis-related factors under conditions of hypoxia, which enhances the angiogenic potential of dental pulp cells. We confirmed that hypoxia regulates the mRNA expression of angiogenesis-related factors, including CXCL16 in dental pulp cells. Furthermore, conditioned media of hypoxic pulp cells induced tube-like structures of vascular endothelial cells, which were reduced by the neutralization of CXCL16 function. In conclusion, our data show that angiogenesis-related factors are differentially expressed by hypoxia in dental pulp cells and suggest that CXCL16 may involve in the revascularization of hypoxic dental pulp.