Zhuan Bian

The performance of dental pulp stem cells on nanofibrous PCL/gelatin/nHA scaffolds

The aim of current study is to investigate the in vitro and in vivo behavior of dental pulp stem cells (DPSCs) seeded on electrospun poly(epsilon-caprolactone) (PCL)/gelatin scaffolds with or without the addition of nano-hydroxyapatite (nHA). For the in vitro evaluation, DNA content, alkaline phosphatase (ALP) activity and osteocalcin (OC) measurement showed that the scaffolds supported DPSC adhesion, proliferation, and odontoblastic differentiation. Moreover, the presence of nHA upregulated ALP activity and promoted OC expression. Real-time PCR data confirmed these results. SEM micrographs qualitatively confirmed the proliferation and mineralization characteristics of DPSCs on both scaffolds. Subsequently, both scaffolds seeded with DPSCs were subcutaneously implanted into immunocompromised nude mice. Scaffolds with nHA but without cells were implanted as control. Histological evaluation revealed that all implants were surrounded by a thin fibrous tissue capsule without any adverse effects. The cell/scaffold composites showed obvious in vivo hard tissue formation, but there was no sign of tissue ingrowth. Further, the combination of nHA in scaffolds did upregulate the expression of specific odontogenic genes. In conclusion, the incorporation of nHA in nanofibers indeed enhanced DPSCs differentiation towards an odontoblast-like phenotype in vitro and in vivo.

Biological Mechanisms in Palatogenesis and Cleft Palate

Clefts of the palate are common birth defects requiring extensive treatment. They appear to be caused by multiple genetic and environmental factors during palatogenesis. This may result in local changes in growth factors, extracellular matrix (ECM), and cell adhesion molecules. Several clefting factors have been implicated by studies in mouse models, while some of these have also been confirmed by genetic screening in humans. Here, we discuss several knockout mouse models to examine the role of specific genes in cleft formation. The cleft is ultimately caused by interference with shelf elevation, attachment, or fusion. Shelf elevation is brought about by mesenchymal proliferation and changes in the ECM induced by growth factors such as TGF-βs. Crucial ECM molecules are collagens, proteoglycans, and glycosaminoglycans. Shelf attachment depends on specific differentiation of the epithelium involving TGF-β3, sonic hedgehog, and WNT signaling, and correct expression of epithelial adhesion molecules such as E-cadherin. The final fusion requires epithelial apoptosis and epithelium-to-mesenchyme transformation regulated by TGF-β and WNT proteins. Other factors may interact with these signaling pathways and contribute to clefting. Normalization of the biological mechanisms regulating palatogenesis in susceptible fetuses is expected to contribute to cleft prevention.

Fibrous scaffolds loaded with protein prepared by blend or coaxial electrospinning

The aim of the present study was to fabricate polycaprolactone-based nanofibrous scaffolds with incorporated protein via either the blend or coaxial electrospinning technique. Both techniques were compared with respect to processing set-up and scaffold characteristics as well as the release kinetics and biological activity of the loaded protein. Bovine serum albumin was used as a model protein to determine release profiles, while alkaline phosphatase was used to determine protein activity after the electrospinning process. Coaxial electrospinning resulted in a uniform fiber morphology with a core-shell structure, and a homogeneous protein distribution throughout the core of the fibers. In contrast, blend electrospinning formed bead-like fibers with a heterogeneous protein distribution in the fibers. The coaxial scaffold exhibited more sustained release profiles than the comparative blend scaffold, and the additive poly(ethylene glycol) (PEG) in the coaxial scaffold accelerated protein release. Both electrospinning processes decreased the biological activity of the incorporated protein, but coaxial electrospinning with PEG as an additive showed up to 75% preservation of the initial biological activity. Thus, coaxial electrospinning was demonstrated to be superior to blend electrospinning for the preparation of nanofibrous scaffolds with a uniform fibrous structure and protein distribution and sustained protein release kinetics as well as high preservation of the protein activity.

In vivo evaluation of human dental pulp stem cells differentiated towards multiple lineages

An increasing number of investigations supports that adult stem cells have the potential to differentiate into matured cell types beyond their origin, a property defined as plasticity. Previously, the plasticity of stem cells derived from dental pulp (DPSC) has been confirmed by culturing cells in lineage‐specific media in vitro. In the current study, the in vivo differentiation or maturation potential of DPSC was further analysed, by transplanting human DPSC/collagen scaffold constructs into subcutaneous tissue of immunocompromised mice. Cells received odontogenic, adipogenic or myogenic pre‐induction, whereas control samples received no stimulation. Also blank collagen scaffolds were implanted. The results indicated that seeded cells produced tissue within the implanted constructs after 3 weeks of implantation. According to morphological and phenotypical changes, the pre‐induced DPSC showed the ability to further differentiate along odontogenic, myogenic and adipogenic pathways in vivo. Moreover, DPSC without pre‐treatment were able to spontaneously differentiate along odontogenic and adipogenic directions in vivo. However, only limited mature morphological changes were detected in histology. In summary, stem cells derived from human dental pulp form a suitable source for tissue engineering and cell‐mediated therapy, although additional analyses should be considered. Copyright

Anti-Inflammatory Activity of Curcumin in Macrophages Stimulated by Lipopolysaccharides from Porphyromonas gingivalis

Background:Porphyromonas gingivalis, a major periodontopathic bacterium, is necessary for periodontitis to take place. The lipopolysaccharide (LPS) of P. gingivalis stimulates cytokine secretion in immune cells, and thereby initiates the inflammation related to periodontitis. Macrophages are the important ones of the immune cells that are prominent at inflammatory periodontal sites. Curcumin, a major curcumanoid found in the spice turmeric, exhibits anti-inflammatory properties. The aim of this study was to investigate the anti-inflammatory effect and the mechanism of action of curcumin in macrophages stimulated by P. gingivalis LPS. Methods: RAW264.7 cells pre-treated with various concentrations of curcumin were stimulated by P. gingivalis LPS. TNF-α and IL-1β expressions were separately detected by RT-PCR and ELISA. Next, activation of NF-ĸB-dependent transcription was examined by luciferase assay. Results: Curcumin dose-dependently inhibited TNF-α and IL-1β gene expression and protein synthesis in RAW264.7 cells stimulated with P. gingivalis LPS. P. gingivalis LPS activated NF-ĸB-dependent transcription in RAW264.7 cells, which were down-regulated by pre-treatment with curcumin as well. Conclusion: Our data suggest that curcumin can inhibit P. gingivalis LPS-induced cytokine expression, and that this could be due to the inhibition of the NF-ĸB pathway.

Self-assessed dental health, oral health practices, and general health behaviors in Chinese urban adolescents.

The objectives of this study were: to describe perceived dental health status and oral health-related knowledge, attitudes, and behavior in Chinese urban adolescents; to assess the associations of oral health variables with socio-economic status and school performance; and to analyse the relative effect of socio-behavioral risk factors on perceived dental health, perceived need for dental care, and experience of dental symptoms. A cross-sectional survey of 2662 adolescents was conducted in eight capital cities in China; the response rate was 92%. The study population was chosen by multistage cluster sampling and covered three age groups: 11, 13, and 15 years. Data on dental and general health were collected by self-administered questionnaires. Self-assessment of dental health of Chinese adolescents was generally good, only 12% of the students answered that their teeth were “poor” or “very poor”, and 9% claimed having “poor” or “very poor” gums. Eleven percent of participants said that other students made fun of their teeth; 24% of the respondents were dissatisfied with the appearance of their teeth, and 41% claimed that they had experienced toothache or symptoms during the previous 12 months. Positive attitudes towards dental care were found in all age groups; 67% of adolescents brushed their teeth at least twice a day and 48% of the students used fluoridated toothpaste. Only 26% of the students visited a dentist during the previous 12 months. In all, 6% of the adolescents had tried cigarette smoking at least once, while 41% reported having tasted alcohol drinks. Multivariate regression analyses showed that perceived dental health status and needs were associated with gender, age, unhealthy lifestyles, poor school performance, and socio-economic status. The establishment of school-based health promotion programs in China is urgently needed, and promotion of oral health lifestyles should be integrated with other general health actions.

Effect of Bioaggregate on Mineral-associated Gene Expression in Osteoblast Cells

INTRODUCTION This study investigated the cytotoxicity of bioaggregate (BA) and the effect of BA on mineral associated gene expression in osteoblast cells. METHODS The cytotoxicity of BA to mouse MC3T3-E1 osteoblast cells was evaluated via the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay after 1, 2, and 3 days of culture. The expression of mineral associated genes (collagen type 1, osteocalcin, and osteopontin) was assessed by quantitative real-time polymerase chain reaction (qRT-PCR) and compared expression after exposure to BA or mineral trioxide aggregate (MTA). The data were analyzed by one-way analysis of variance and the Tukey test. RESULTS BA was essentially nontoxic to osteoblast cells. The expression of collagen type 1, osteocalcin, and osteopontin genes significantly increased in the BA group compared with that in the MTA group on the second or third day of culture. CONCLUSION BA appears to be a novel nontoxic root-end filling biomaterial and be able to induce mineralization-associated gene expression in osteoblast cells.

Non-viral bone morphogenetic protein 2 transfection of rat dental pulp stem cells using calcium phosphate nanoparticles as carriers.

Calcium phosphate nanoparticles have shown potential as non-viral vectors for gene delivery. The aim of this study was to induce bone morphogenetic protein (Bmp)2 transfection in rat dental pulp stem cells using calcium phosphate nanoparticles as a gene vector and then to evaluate the efficiency and bioactivity of the transfection. We also intended to investigate the behavior of transfected cells when seeded on 3-dimensional titanium fiber mesh scaffolds. Nanoparticles of calcium phosphate encapsulating plasmid deoxyribonucleic acid (DNA) (plasmid enhanced green fluorescent protein-BMP2) were prepared. Then, STRO-1-selected rat dental pulp stem cells were transfected using these nanoparticles. Transfection and bioactivity of the secreted BMP2 were examined. Thereafter, the transfected cells were cultured on a fibrous titanium mesh. The cultures were investigated using scanning electron microscipy and evaluated for cell proliferation, alkaline phosphatase activity and calcium content. Finally, real-time polymerase chain reaction was performed for odontogenesis-related gene expression. The results showed that the size of the DNA-loaded particles was approximately 100 nm in diameter. Nanoparticles could protect the DNA encapsulated inside from external DNase and release the loaded DNA in a low-acid environment (pH 3.0). In vitro, nanoparticle transfection was shown to be effective and to accelerate or promote the odontogenic differentiation of rat dental pulp stem cells when cultured in the 3-dimensional scaffolds. Based on our results, plasmid DNA-loaded calcium phosphate nanoparticles appear to be an effective non-viral vector for gene delivery and functioned well for odontogenic differentiation through Bmp2 transfection.

Blocking antibody to the β-subunit of FSH prevents bone loss by inhibiting bone resorption and stimulating bone synthesis

Low estrogen levels undoubtedly underlie menopausal bone thinning. However, rapid and profuse bone loss begins 3 y before the last menstrual period, when serum estrogen is relatively normal. We have shown that the pituitary hormone FSH, the levels of which are high during late perimenopause, directly stimulates bone resorption by osteoclasts. Here, we generated and characterized a polyclonal antibody to a 13-amino-acid-long peptide sequence within the receptor-binding domain of the FSH β-subunit. We show that the FSH antibody binds FSH specifically and blocks its action on osteoclast formation in vitro. When injected into ovariectomized mice, the FSH antibody attenuates bone loss significantly not only by inhibiting bone resorption, but also by stimulating bone formation, a yet uncharacterized action of FSH that we report herein. Mesenchymal cells isolated from mice treated with the FSH antibody show greater osteoblast precursor colony counts, similarly to mesenchymal cells isolated from FSH receptor (FSHR)−/− mice. This suggests that FSH negatively regulates osteoblast number. We confirm that this action is mediated by signaling-efficient FSHRs present on mesenchymal stem cells. Overall, the data prompt the future development of an FSH-blocking agent as a means of uncoupling bone formation and bone resorption to a therapeutic advantage in humans.

Oral and general health behaviours among Chinese urban adolescents

OBJECTIVES The objectives of this study were to measure the association of general and oral health-related behaviours with living conditions and to explore the interrelationships between general and oral health-related behaviours in Chinese urban adolescents. METHODS A cross-sectional survey of 2662 adolescents was conducted in eight Chinese provincial capitals. The response rate was 92%. The study population was selected through multistage cluster sampling and comprised three age groups: 11, 13 and 15 years. Data on oral and general health, lifestyles as well as living conditions were collected by means of self-administered structured questionnaires. Several additive indices were constructed from answers to the questions on specific behaviour, and participants were categorized according to scores on each component of health-related behaviour for statistical analyses by frequency distributions, regression analyses and factor analyses. RESULTS Oral health-related behaviours among adolescents were associated with socioeconomic status of parents, school performance and peer relationships. The odds of a dental visit was 0.63 in adolescents of poorly educated parents and the corresponding figure for regular oral hygiene practices was 0.62. Odds of tobacco use was 3 for adolescents with poor performance in school while odds of consuming sugary foods/drinks was 1.3. Adolescents with high levels of preventive oral health practices also demonstrated general health-promoting behaviours. In factor analysis of general and oral health-related behaviours, three factors were isolated: (a) risk behaviours (loadings 0.48-0.66), (b) health-promoting behaviours (loadings 0.60-0.64) and (c) help-seeking behaviours (loadings 0.56-0.67). CONCLUSION The findings support a multidimensional model of health behaviour. Several approaches and multiple methods should be applied in oral health education in order to modify behaviours that affect oral health.