Weibin Sun

Silk scaffolds for dental tissue engineering

Abstract: Silk-based biomaterial scaffolds have been extensively used for both soft and hard tissue engineering. This is due to their various physical characteristics, biocompatibility and ability to support the attachment, proliferation and differentiation of many different cell types. Although cardiac diseases, diabetes and obesity are typically major problems in the developed world, dental patients far outweigh those with these conditions and are responsible for huge costs to medical providers. This chapter will discuss the clinical challenges in dentistry, the current status of dental tissue engineering and the background and future potential of using silk scaffolds for dental tissue engineering.

Electrospun fibrous scaffolds combined with nanoscale hydroxyapatite induce osteogenic differentiation of human periodontal ligament cells

Periodontal repair is a complex process in which regeneration of alveolar bone is a vital component. The aim of this study was to develop a biodegradable scaffold with good biocompatibility and osteoinductive ability. Two types of composite fibrous scaffolds were produced by electrospinning, ie, type I collagen/poly(ε-caprolactone) (COL/PCL) and type I collagen/poly(ε-caprolactone)/nanoscale hydroxyapatite (COL/PCL/nHA) with an average fiber diameter of about 377 nm. After a simulated body fluid (SBF) immersion test, the COL/PCL/nHA-SBF scaffold developed a rough surface because of the calcium phosphate deposited on the fibers, suggesting that the presence of nHA promoted the mineralization potential of the scaffold. Energy dispersive X-ray spectroscopy clearly showed the calcium and phosphorus content in the COL/PCL/nHA and COL/PCL/nHA-SBF scaffolds, confirming the findings of nHA and calcium phosphate precipitation on scanning electron micrographs. Water contact analysis revealed that nHA could improve the hydrophilic nature of the COL/PCL/nHA-SBF scaffold. The morphology of periodontal ligament cells cultured on COL/PCL-SBF and COL/PCL/nHA-SBF was evaluated by scanning electron microscopy. The results showed that cells adhered to either type of scaffold and were slightly spindle-shaped in the beginning, then extended gradually with stretched filopodia, indicating an ability to fill the fiber pores. A Cell Counting Kit-8 assay showed that both scaffolds supported cell proliferation. However, real-time quantitative polymerase chain reaction analysis showed that expression of the bone-related markers, alkaline phosphatase and osteocalcin, was upregulated only on the COL/PCL/nHA-SBF scaffold, indicating that this scaffold had the ability to induce osteogenic differentiation of periodontal ligament cells. In this study, COL/PCL/nHA-SBF produced by electrospinning followed by biomimetic mineralization had combined electrospun fibers with nHA in it. This scaffold has good biocompatibility and osteoinductive ability as a result of the characteristics of nHA, so could be innovatively applied to periodontal tissue engineering as a potential scaffold.

Porphyromonas gingivalis Infection Reduces Regulatory T Cells in Infected Atherosclerosis Patients

Increasing evidence has shown periodontal pathogen Porphyromonas gingivalis (P.gingivalis) infection contributes to atherosclerosis (AS) progression. P.gingivalis fimbriae act as an important virulence factor in AS. Regulatory T cells (Tregs) may play a crucial role in autoimmune response during this process. However, whether P.gingivalis infection is associated with Tregs dysregulation during AS is still unknown and the prevalence of different P.gingivalis FimA genotypes during this process is unclear. Here we analyzed the distribution of Tregs and in P.gingivalis-infected atherosclerotic patients to reveal the relationship between P.gingivalis infection and Tregs reduction/dysfunction and to elucidate their role in periodontitis-AS interaction. FimA genotype was also examined to determine the prevalence of fimbriae. Our results showed that P.gingivalis infection reduced Tregs in atherosclerotic patients compared with non-atherosclerotic patients and health controls. Concentration of TGF-β1, which plays an important role in the development of Tregs, also decreased in P.gingivalis infected patients. Furthermore, type II FimA seems to show higher prevalence than the other five detected types. The population of Tregs further decreased in patients with type II FimA compared with the other types. P.gingivlias FimA genotype II was the dominant type associated with decreased Treg population. These results indicate that P.gingivalis infection may be associated with Tregs dysregulation in AS; type II FimA may be a predominant genotype in this process.

The synthesis of hydroxyapatite with different crystallinities by controlling the concentration of recombinant CEMP1 for biological application.

Cementum protein 1 (CEMP1) has been reported to be cementum specific and it plays a role in the properties and structure of cementum mineralization. This study was carried out to test the hypothesis that, CEMP1 had the capacity to guide ordered HA formation as it accumulated at targeting site. Crystals induced by protein were prepared by biomimetic method. The effects of CEMP1 concentrations (0-100μg/ml) on the rate of calcium phosphate precipitation was monitored during 48h, while the formed mineral phases were assessed utilizing transmission electron microscope (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results showed that recombinant cementum protein 1 (rhCEMP1) affected the crystal nucleation and growth. At lower rhCEMP1 concentrations (0-50μg/ml), limited mineral formation occurred and only small bundles of HA crystals were found. However, with 100μg/ml of rhCEMP1, a predominance of organized linear needle-like HA crystals was observed. FTIR revealed the characteristic bands of HA appearing at 1106cm(-1), 557cm(-1), and 598cm(-1). Therefore, increasing the concentration of rhCEMP1 can lead to the formation of ordered bundles of HA crystals in vitro.

Multiple idiopathic cervical root resorption: a case report

AIM To report a severe and rare case of multiple idiopathic cervical root resorption (MICRR) in an adult female. SUMMARY A healthy 27-year-old Chinese female, with no significant associated factors, presented with MICRR. Resorption progressed quickly and lesions varied in severity, involving 29 teeth and leading to the loss of 23 teeth over a period of only 3 years. The inner surface of the crown showed extensive areas with worm-eaten lacunar resorption, and the resorptive lesions had abundant lysosomes throughout their cytoplasm. Further, heavy deposits of reaction products were shown in variously sized lysosomes.

Effect of deletion of the rgpA gene on selected virulence of Porphyromonas gingivalis

Background/purpose The most potent virulence factors of the periodontal pathogen Porphyromonas gingivalis are gingipains, three cysteine proteases (RgpA, RgpB, and Kgp) that bind and cleave a wide range of host proteins. Considerable proof indicates that RgpA contributes to the entire virulence of the organism and increases the risk of periodontal disease by disrupting the host immune defense and destroying the host tissue. However, the functional significance of this proteinase is incompletely understood. It is important to analyze the effect of arginine-specific gingipain A gene (rgpA) on selected virulence and physiological properties of P. gingivalis. Materials and methods Electroporation and homologous recombination were used to construct an rgpA mutant of P. gingivalis ATCC33277. The mutant was verified by polymerase chain reaction and sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Cell structures of the mutant were examined by transmission electron microscopy and homotypic biofilm formation was examined by confocal laser scanning microscopy. Results Gene analysis revealed that the rgpA gene was deleted and replaced by a drug resistance gene marker. The defect of the gene resulted in a complete loss of RgpA proteinase, a reduction of out membrane vesicles and hemagglutination, and an increase in homotypic biofilm formation. Conclusion Our data indicate that an rgpA gene deficient strain of P. gingivalis is successfully isolated. RgpA may have a variety of physiological and pathological roles in P. gingivalis.

Application of OSCE for Stage Assessment in Standardized Training for Oral Residents

The aim of this study was to establish and implement an objective structured clinical examination (OSCE) for stage assessment in standardized training for oral residents, evaluating its validity and suitability. An OSCE was established for stage assessment of 158 residents in a program in Jiangsu Province, China. Its validity and suitability were evaluated using indices such as reliability and discrimination coefficients of assessment results. The established OSCE had eight stations: interpretation of auxiliary examination results, basic knowledge, doctor-patient communication and clinical examination, clinical case analysis, medical record and prescription writing, public skills, first aid skills, and specialists operation skills. The mean overall score and consistency coefficient (Cronbachs alpha) for the test subjects were 83.64±3.69 points and 0.732, respectively. The developed OSCE was reasonably established, with credible assessment results, and indices such as mean and discrimination coefficient of test scores from each station were appropriate. Therefore, the proposed protocol was found to be reliable and suitable.

A Chinese family with periodontal Ehlers−Danlos Syndrome associated with missense mutation in the C1R gene

AIM We report a rare case of the periodontal Ehlers-Danlos syndrome (pEDS) associated with severe periodontitis and tooth loss in a Chinese family. MATERIAL AND METHODS The proband complained of gingival bleeding and mobility, which were also reported in his mother, and maternal uncle and his maternal grandmother and great-grandfather in the past. All family members underwent oral, physical, dermatological, and genetic examinations. RESULTS Oral manifestation of family members affected with pEDS presented severe periodontitis with multiple or total tooth loss. The proband displayed unique clinical manifestations including a characteristic facial appearance and thin, translucent skin with easily visible venous patterns on feet. Whole-exome sequencing identified missense mutation c.265T>C in C1R in all affected family members tested and frameshift mutation c.1322delG in COL3A1 in the proband alone. None of the unaffected members showed any marked oral, physical, dermatological, or genetic findings. CONCLUSION We reported an extremely rare case of pEDS with a missense mutation in C1R in a Chinese family, with coexistence C1R and COL3A1 mutations in the proband who was suspected to suffer from vascular EDS as well. To our knowledge, this is the first case of coexistence of two forms of EDS in a single individual.

Porphyromonas gingivalis oral infection promote T helper 17/Treg imbalance in the development of atherosclerosis

Background/purpose Increasing studies have indicated the involvement of Porphyromonas gingivalis in atherosclerosis. T helper 17 (Th17)/Treg balance is critical during atherosclerosis. However, whether P. gingivalis oral infection is associated with Th17/Treg imbalance is unclear. The aim of the present study was to investigate the effect of P. gingivalis on Th17/Treg balance during atherosclerosis. Materials and methods ApoE–/– and C57BL/6 mice were inoculated orally with P. gingivalis ATCC 33277 for 9 weeks. The alveolar bone loss was assessed by microcomputerized tomography. The area of atherosclerosis plaque was identified by oil red O staining. Plaque stability was analyzed by CD68 and αSMA immunohistochemistry staining and Masson staining. The frequency of Th17 and Treg in spleen was detected by flow cytometry. The mRNA expression of Th17- and Treg-related factors was determined by quantitative polymerase chain reaction. Interleukin (IL)-6, a critical factor in modulating T-cell differentiation, was determined from spleen cells and mouse dendritic cells by enzyme-linked immunosorbent assay. Results Long-term P. gingivalis oral infection induced alveolar bone resorption. In ApoE–/– mice, P. gingivalis enhanced atherosclerotic lesion formation and plaque instability accompanied with a decreased Treg frequency and an increased Th17 cell frequency. In addition, mRNA expression of retinoic acid receptor-related orphan receptor γt and IL-17 was increased, and that of transforming growth factor (TGF) β and IL-10 was decreased in P. gingivalis-infected ApoE–/– mice. Furthermore, secretion of IL-6 was elevated in the spleen of P. gingivalis-infected ApoE–/– mice, as well as in mouse dendritic cells after P. gingivalis infection. Conclusion P. gingivalis oral infection may promote Th17/Treg imbalance by influencing T-cell differentiation during the process of atherosclerosis, with a larger lesion area and decreasing plaque instability.

Aligned Fibers Fabricated by Near-Field Electrospinning Influence the Orientation and Differentiation of hPDLSCs for Periodontal Regeneration

The periodontal ligament (PDL) is a specific connective tissue composed of organized and aligned collagenous fibers that fix the tooth root in the alveolar bone. The alignment of PDL fibers and their function have been neglected in the past, as many studies investigated the regeneration of the periodontium, including alveolar bone and cementum regeneration. In this study, we fabricated biodegradable aligned fibers (ε-caprolactone/collagen) by near-field electrospinning (NFE) to control the arrangement of human periodontal ligament stem cells (hPDLSCs), aiming to guide the oriented regeneration of the periodontal ligament. Compared with random electrospun fibers, the in vitro study investigated the effects of nanotopography on stem cell differentiation of hPDLSCs. The hPDLSCs were identified by flow cytometry, and the multipotency of hPDLSCs was confirmed by successful osteogenic induction. The hPDLSCs were co-cultured with aligned and random fibers. The cell morphology was observed by confocal micrograph and scanning electron micrograph, which showed that aligned fibers could guide the orientation and elongation of hPDLSCs. The expression of periodontal ligament-related genes was higher when cultured with aligned fibers than when cultured with random fibers. In conclusion, via near-field electrospinning, aligned biodegradable fibers were prepared and guided the orientation arrangement of hPDLSCs, providing a better microenvironment for periodontal ligament regeneration. This technology might be further used in the regeneration of tissues in a given direction.