Periodontal Ligament Cell Sheets and RGD-Modified Chitosan Improved Regeneration in the Horizontal Periodontal Defect Model

Effects of Chrysin on Oral Squamous Cell Carcinoma In Vitro

OBJECTIVE

 Chrysin is a hydroxylated flavonoid derived from "propolis or bee glue," a natural product. Previous research on chrysin's biological functions, including anticancer activity, had been reported. However, chrysin's effect on oral squamous cell carcinoma (OSCC) is still scarce. This article aimed to test the cytotoxicity, antiproliferative, antimigration, anti-invasion, and apoptotic effects of purified chrysin in two OSCC cell lines, HSC4 and SCC25.

MATERIALS AND METHODS

 The malignant phenotype was assessed using cell proliferation, wound healing, and transwell assays. Cell apoptosis was determined using flow cytometry. The positive control was OSCC cells treated with cisplatin, and the negative control was OSCC cells incubated with 0.1% dimethyl sulfoxide.

RESULTS

 Chrysin at concentrations of 100 and 200 µM could inhibit OSCC cell proliferation, migration, and invasion, as well as enhance cell apoptosis, particularly in the early stages of apoptosis.

CONCLUSION

 In OSCC cell lines, chrysin has been demonstrated to be an effective antioncogenic agent. Additional research is required to confirm the results. Chrysin should be suggested as a possible alternative therapeutic application for OSCC.

Hydrogel-Based Biomaterial as a Scaffold for Gingival Regeneration: A Systematic Review of In Vitro Studies

BACKGROUND

Hydrogel is considered a promising scaffold biomaterial for gingival regeneration. In vitro experiments were carried out to test new potential biomaterials for future clinical practice. The systematic review of such in vitro studies could synthesize evidence of the characteristics of the developing biomaterials. This systematic review aimed to identify and synthesize in vitro studies that assessed the hydrogel scaffold for gingival regeneration.

METHODS

Data on experimental studies on the physical and biological properties of hydrogel were synthesized. A systematic review of the PubMed, Embase, ScienceDirect, and Scopus databases was conducted according to the Preferred Reporting System for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement guidelines. In total, 12 original articles on the physical and biological properties of hydrogels for gingival regeneration, published in the last 10 years, were identified.

RESULTS

One study only performed physical property analyses, two studies only performed biological property analyses, and nine studies performed both physical and biological property analyses. The incorporation of various natural polymers such as collagen, chitosan, and hyaluronic acids improved the biomaterial characteristics. The use of synthetic polymers faced some drawbacks in their physical and biological properties. Peptides, such as growth factors and arginine-glycine-aspartic acid (RGD), can be used to enhance cell adhesion and migration. Based on the available primary studies, all studies successfully present the potential of hydrogel characteristics in vitro and highlight the essential biomaterial properties for future periodontal regenerative treatment.

Basic fibroblast growth factor/chitosan derivatives/collagen composite thermosensitive hydrogel promotes perio-dontal tissue regeneration in rats

OBJECTIVES

To investigate the feasibility of different thermosensitive composite hydrogels from chitosan derivatives as scaffold materials for periodontal tissue engineering.

METHODS

Three chitosan derivatives with different biological characteristics were prepared, namely, sulfonated chitosan (SCS), phosphorylated chitosan (PCS), and phosphorylated sulfonated chitosan (PSCS). Three thermosensitive composite hydrogels were constructed using basic fibroblast growth factor (bFGF), the chitosan derivatives, and collagen. Twenty male Wistar rats were randomly divided into control group, blank group, bFGF/SCS/collagen composite thermosensitive hydrogel group, bFGF/PCS/collagen compo-site thermosensitive hydrogel group, and bFGF/PSCS/collagen composite thermosensitive hydrogel group. Then, three-wall intrabony defects were established. The defects were treated with the different kinds of thermosensitive composite hydrogels. After 6 weeks of surgery, the animals were killed, and specimens were collected. Then, gross observation, hematoxylin-eosin staining, and Masson staining were performed.

RESULTS

The bFGF/chitosan derivatives/collagen composite thermosensitive hydrogel groups and the control group had statistical differences in the relative alveolar bone height, relative epithelial down growth and grading count score of periodontal tissue regeneration (P<0.05).

CONCLUSIONS

bFGF/chitosan derivatives/collagen composite thermosensitive hydrogels have good application prospects in periodontal tissue engineering.

Biomaterials and biotechnology for periodontal tissue regeneration: Recent advances and perspectives

Periodontal tissues are organized in a complex three-dimensional (3D) architecture, including the alveolar bone, cementum, and a highly aligned periodontal ligament (PDL). Regeneration is difficult due to the complex structure of these tissues. Currently, materials are developing rapidly, among which synthetic polymers and hydrogels have extensive applications. Moreover, techniques have made a spurt of progress. By applying guided tissue regeneration (GTR) to hydrogels and cell sheets and using 3D printing, a scaffold with an elaborate biomimetic structure can be constructed to guide the orientation of fibers. The incorporation of cells and biotic factors improves regeneration. Nevertheless, the current studies lack long-term effect tracking, clinical research, and in-depth mechanistic research. In summary, periodontal tissue engineering still has considerable room for development. The development of materials and techniques and an in-depth study of the mechanism will provide an impetus for periodontal regeneration.

In Silico Analysis of Glycosaminoglycan-Acemannan as a Scaffold Material on Alveolar Bone Healing

OBJECTIVE

 This study aimed to analyze interaction between glycosaminoglycan-acemannan as a scaffold material and toll-like receptor-2 (TLR-2) receptor, which predicted the osteogenesis potency on alveolar bone healing (in silico analysis).

MATERIALS AND METHODS

 Docking interaction between glycosaminoglycan-acemannan and TLR-2 receptor using the Molegro Virtual Docker (MVD) program. The compounds of glycosaminoglycan-acemannan and TLR-2 receptor with the structure in the form of two- and three-dimensional images were analyzed, as well as the most stable structure. It was observed the interaction of the ligand on the cavity of the TLR-2 receptor structure. The energy required for the ligand and receptor interaction (Moldock score) was calculated with MPD program.

RESULTS

 The chemical structure shows that glycosaminoglycan-acemannan is capable binding to the TLR-2 receptor with hydrogen bonds and strong steric interaction. The docking results were detected for five cavities where the compound binds to the TLR-2 receptor. The Moldock score of the ligand on the CAS-LYS-LEU-ARG-LYS-ILE-MSE[A] ligand was -95,58 Kcal/mol, that of acemannan was -91,96 Kcal/mol, and for glycosaminoglycan -61,14 Kcal/mol.

CONCLUSION

 The compound of glycosaminoglycan-acemannan as a scaffold material is able to bind with a TLR-2 target receptor, which predicted osteogenesis activity on alveolar bone healing supported by in silico analysis.

IL-7-Treated Periodontal Ligament Cells Regulate Local Immune Homeostasis by Modulating Treg/Th17 Cell Polarization

Both interleukin (IL)-7 and human periodontal ligament cells (hPDLCs) have immunomodulatory properties. However, their combined effect on CD4⁺T cells has never been studied. In this study, we aimed to investigate the effect of conditioned medium of hPDLCs treated with rhIL-7 on the differentiation of CD4⁺T cells into regulatory T cells/T helper 17 cells (Treg/Th17 cells) and observe the effect of IL-7 on the immunomodulatory properties of PDLCs. After hPDLCs were treated with different concentrations of rhIL-7 for 24 h, the collected supernatants were used to incubate CD4⁺T cells for 3 days. A gamma-secretase inhibitor (DAPT) was used to suppress the activation of the Notch1 signaling pathway. Cell proliferation, apoptosis, and necrosis were determined using the cell counting kit-8 (CCK-8) and flow cytometry (FCM). The expressions of forkhead box P3 (Foxp3) in CD4⁺T cells and transforming growth factor (TGF-β) and IL-6 in the supernatants were determined by ELISA. Reverse transcription-quantitative PCR (RT-qPCR), and the Western blot (WB) determined the mRNA levels and protein expression of various target factors. FCM was used to detect the mean fluorescence intensity of PD-L1 in hPDLCs and to analyze the differentiation of Treg/Th17 cells. Our results showed that IL-7 promoted proliferation and inhibited apoptosis in hPDLCs, promoted the expression of TGF-β, PD-L1, Notch1, Jagged1, and Hes1, and inhibited the levels of hypoxia-inducible factor (HIF)-1α and TCF7, whereas the addition of DAPT effectively reversed these effects. Importantly, we found that the conditioned medium of hPDLCs treated with rhIL-7 promoted the polarization of CD4⁺T cells into Treg cells but had no significant effect on the differentiation of Th17 cells. Our study indicated that treatment of PDLCs with IL-7 can promote the polarization of CD4⁺T cells into Treg cells by modulating the expression of inflammatory factors and signaling molecules through activating the Notch1 signaling pathway, thus participating in the regulation of immune homeostasis in the periodontal microenvironment.

The recent advances in scaffolds for integrated periodontal regeneration

The periodontium is an integrated, functional unit of multiple tissues surrounding and supporting the tooth, including but not limited to cementum (CM), periodontal ligament (PDL) and alveolar bone (AB). Periodontal tissues can be destructed by chronic periodontal disease, which can lead to tooth loss. In support of the treatment for periodontally diseased tooth, various biomaterials have been applied starting as a contact inhibition membrane in the guided tissue regeneration (GTR) that is the current gold standard in dental clinic. Recently, various biomaterials have been prepared in a form of tissue engineering scaffold to facilitate the regeneration of damaged periodontal tissues. From a physical substrate to support healing of a single type of periodontal tissue to multi-phase/bioactive scaffold system to guide an integrated regeneration of periodontium, technologies for scaffold fabrication have emerged in last years. This review covers the recent advancements in development of scaffolds designed for periodontal tissue regeneration and their efficacy tested in vitro and in vivo. Pros and Cons of different biomaterials and design parameters implemented for periodontal tissue regeneration are also discussed, including future perspectives.

Anti-Inflammatory and Antibacterial Activity of the Chitosan/Chlorhexidine Gel Commercial Preparation for Postexodontia Treatment: An In Vitro Study

Objective  The present study aimed to assess in vitro the antibacterial activity, cytotoxicity, and the expression of prostaglandin E ₂ (PGE ₂ ) of Bexident post topical gel (BP).

Materials and Methods  The broth dilution test was performed to analyze the antimicrobial activity of BP against Staphylococcus aureus , Escherichia coli , and Streptococcus mutans . Minimal bactericidal concentrations (MBCs) and minimal inhibitory concentrations (MICs) were assessed. Cytotoxic activity was performed by the MTT (tetrazolium dye) method on human gingival fibroblast (HGF), human bone cells (HBC), and human pulp cells (HPC) (from primary cell culture) and HGF-1 from American Type Culture Collection. The expression of PGE ₂ produced by RAW 264.7 cells was determined by ELISA utilizing an Enzyme Immuno-Assay Kit.

Statistical Analysis  Shapiro–Wilks normality test and Mann–Whitney U test were performed for all data.

Results  The MBCs of BP for S. aureus , E. coli , and S. mutans were found at 25, 50, and 12.5%, respectively. The MICs for the same strains were found at 12.5, 25, and 3.125%. The CC ₅₀ of BP gel for HBC, HPC, and HGF, and HGF-1 were 12.5 ± 1.09, 0.37 ± 0.02, 0.35 ± 0.02, and 20.4 ± 0.02%, respectively. The levels of expression PGE ₂ produced by RAW 264.7 cells treated with IL-1β exhibit an inverse dose-dependent effect on the concentrations of BP gel used.

Conclusion  Our results indicate that the BP gel has a great antibacterial effect, adequate biocompatibility, showing a decrease in the expression of PGE ₂ on cells with previously induced inflammation. Due to the above, its use as a healing agent after oral surgery seems to be adequate.