iRoot SP Promotes Osteo/Odontogenesis of Bone Marrow Mesenchymal Stem Cells via Activation of NF-κB and MAPK Signaling Pathways

Shear stress and pathophysiological PI3K involvement in vascular malformations

Molecular characterization of vascular anomalies has revealed that affected endothelial cells (ECs) harbor gain-of-function (GOF) mutations in the gene encoding the catalytic α subunit of PI3Kα (PIK3CA). These PIK3CA mutations are known to cause solid cancers when occurring in other tissues. PIK3CA-related vascular anomalies, or "PIKopathies," range from simple, i.e., restricted to a particular form of malformation, to complex, i.e., presenting with a range of hyperplasia phenotypes, including the PIK3CA-related overgrowth spectrum. Interestingly, development of PIKopathies is affected by fluid shear stress (FSS), a physiological stimulus caused by blood or lymph flow. These findings implicate PI3K in mediating physiological EC responses to FSS conditions characteristic of lymphatic and capillary vessel beds. Consistent with this hypothesis, increased PI3K signaling also contributes to cerebral cavernous malformations, a vascular disorder that affects low-perfused brain venous capillaries. Because the GOF activity of PI3K and its signaling partners are excellent drug targets, understanding PIK3CA's role in the development of vascular anomalies may inform therapeutic strategies to normalize EC responses in the diseased state. This Review focuses on PIK3CA's role in mediating EC responses to FSS and discusses current understanding of PIK3CA dysregulation in a range of vascular anomalies that particularly affect low-perfused regions of the vasculature. We also discuss recent surprising findings linking increased PI3K signaling to fast-flow arteriovenous malformations in hereditary hemorrhagic telangiectasias.

Comparative bioactivity and immunomodulatory potential of the new Bioroot Flow and AH Plus Bioceramic sealer: An in vitro study on hPDLSCs

OBJECTIVES

To evaluate the cytocompatibility, bioactivity, and anti-inflammatory potential of the new pre-mixed calcium silicate cement-based sealers Bioroot Flow (BrF) and AH Plus Bioceramic Sealer (AHPbcs) on human periodontal ligament stem cells (hPDLSCs) compared to the epoxy resin-based sealer AH Plus (AHP).

MATERIALS AND METHODS

Standardized discs and 1:1, 1:2, and 1:4 eluates of BrF, AHPbcs and AHP after setting were prepared. The following assays were performed: cell attachment and morphology via SEM, cell viability via a MTT assay, cell migration/proliferation via a wound-healing assay, cytoskeleton organization via immunofluorescence staining; cytokine release via ELISA; osteo/cemento/odontogenic marker expression via RT-qPCR, and cell mineralized nodule formation via Alizarin Red S staining. HPDLSCs were isolated from extracted third molars from healthy patients. Comparisons were made with hPDLSCs cultured in unconditioned (negative control) or osteogenic (positive control) culture media. Statistical significance was established at p < 0.05.

RESULTS

Both BrF and AHPbcs showed significantly positive results in the cytocompatibility assays (cell metabolic activity, migration, attachment, morphology, and cytoskeleton organization) compared with a negative control group, while AHP showed significant negative results. BrF exhibited an upregulation of at least one osteo/cementogenic marker compared to the negative and positive control groups. BrF showed a significantly higher calcified nodule formation than AHPbcs, the negative and positive control groups, while AHPbcs was higher than the negative control group. Both were also significantly higher than AHP group.

CONCLUSION

BrF and AHPbcs exhibit adequate and comparable cytocompatibility on hPDLSCs. BrF also promoted the osteo/cementogenic differentiation of hPDLSCs. Both calcium silicate-based sealers favored the downregulation of the inflammatory cytokine IL-6 and the calcified nodule formation from hPDLSCs. BrF exerted a significantly higher influence on cell mineralization than AHPbcs.

CLINICAL RELEVANCE

This is the first study to elucidate the biological properties and immunomodulatory potential of Bioroot Flow and AH Plus Bioceramic Sealer. The results act as supporting evidence for their use in root canal treatment.

A comparative study of biological properties of three root canal sealers

OBJECTIVES

The aim of this study was to evaluate the effects of Hiflow with other two kinds of root canal sealers on the biological behavior of stem cells from the apical papilla (SCAP), the influence on inflammatory cytokines release and its antibacterial effects.

MATERIALS AND METHODS

Material extracts of Hiflow, iRoot SP, and AH Plus were prepared. Then, SCAP was incubated with extracts. The effects were evaluated by CCK-8, wound healing assay, ALP staining, alizarin red staining, and qRT-PCR. Meanwhile, polymorphonuclears (PMNs) and monocytes were isolated and treated with extracts for 4 h and 24 h respectively. Cell viability was analyzed by Annexin-V/PI double staining flow cytometry. The effects on the release of cytokines were observed by ELISA. The antibacterial effects of different sealers were tested against three kinds of bacteria found in chronic apical periodontitis.

RESULTS

A series of results of SCAP showed that Hiflow and iRoot SP could promote cell proliferation, migration, and osteogenesis (p < 0.05). Although Hiflow was associated with greater cell apoptosis and necrosis when incubated with PMNs and monocytes (p < 0.05), it had an approximate release of anti-inflammatory cytokines with iRoot SP, which was higher than AH plus (p < 0.05). The co-culture showed that Hiflow and iRoot SP inhibited the colony formation of F. nucleatum (p < 0.05). However, both sealers had no obvious antibacterial effect on E. faecalis and P. gingivalis (p > 0.05).

CONCLUSIONS

In summary, Hiflow and iRoot SP both had positive biological stimulus on SCAP. Meanwhile, Hiflow showed a better induction on anti-inflammatory cytokines over the others. All the properties mentioned above and its antibacterial effect of F. nucleatum promise Hiflow a bright application prospect in endodontic uses.

CLINICAL RELEVANCE

References for clinical work to use BC Sealer Hiflow as a good biological root canal sealer.

The bioceramic sealer iRoot SP promotes osteogenic differentiation of human stem cells from apical papilla via miR-141-3p/SPAG9/MAPK signalling pathway

AIM

The premixed bioceramic sealer iRoot SP that is widely used clinically has been reported to kill bacterial biofilms and promote osteogenic differentiation of human stem cells from the apical papilla (hSCAPs). Although miR-141-3p has been substantiated to be involved in the osteogenic process, the underlying mechanisms remain unclear. The aim of this study was to investigate the role of miR-141-3p in osteogenic differentiation and underlying mechanisms of iRoot SP-treated hSCAPs.

METHODOLOGY

hSCAPs were extracted from tissue blocks with enzyme digestion and identified by using immunofluorescence, flow cytometry and alizarin red staining. The mRNA expression level of miR-141-3p in hSCPAs after culture with iRoot SP was examined by quantitative real-time PCR (qRT-PCR) assay. SPAG9 was identified as a downstream target gene of miR-141-3p by dual-luciferase report assay. Alkaline phosphatase (ALP) staining and activity detection, alizarin red staining, calcium concentration assay, qRT-PCR and western blot were used to estimate osteogenic differentiation ability and involved protein expression levels of the osteogenic makers and signalling pathway-related factors in iRoot SP-treated hSCAPs. Data were analysed by one-way anova and post hoc Tukey's test to determine any statistical differences between the experimental groups and the control group. p < .05 was considered statistically significant.

RESULTS

Expression of miR-141-3p was reduced in iRoot SP-treated hSCAPs with the increased exposure time up to 7 days, and the western blot and qRT-PCR results revealed that the osteogenic markers osteocalcin (OCN), osterix (OSX), runt-related transcription factor 2 (RUNX2) and dentin sialophosphoprotein (DSPP) were inversely correlated with miR-141-3p. The negative regulatory relationship between miR-141-3p and SPAG9/ mitogen-activated protein kinases (MAPK) signalling axis was validated in this in vitro experiments.

CONCLUSIONS

The bioceramic sealer iRoot SP promoted osteogenic differentiation of hSCAPs by inhibiting miR-141-3p following down-regulated SPAG9 expression, and activated MAPK pathway. These findings proposed a novel therapeutic impact of bioceramic sealer iRoot SP inducing bone regeneration in refractory periapical periodontitis.

A Review of the research methods and progress of biocompatibility evaluation of root canal sealers

The function of root canal sealer was to achieve an appropriate three-dimensional filling effect by filling the root canal and some irregular lumen, thereby inhibiting the residual bacteria. There were many types of sealers, but research to find the most suitable ones was still ongoing. In recent years, researchers had continuously improved the performance of sealers by developing new sealers or adding active ingredients to the sealers. However, most sealers exhibit varying degrees of cytotoxicity and tissue responses, which affect clinical therapy efficacy. This review describes different technical approaches, and recent research progress in the biocompatibility evaluation of root canal sealers and provides brief insights into this field by summarising the performance studies of different root canal sealers.

Phosphoserine-loaded chitosan membranes promote bone regeneration by activating endogenous stem cells

Bone defects that result from trauma, infection, surgery, or congenital malformation can severely affect the quality of life. To address this clinical problem, a phosphoserine-loaded chitosan membrane that consists of chitosan membranes serving as the scaffold support to accommodate endogenous stem cells and phosphoserine is synthesized. The introduction of phosphoserine greatly improves the osteogenic effect of the chitosan membranes via mutual crosslinking using a crosslinker (EDC, 1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimide). The morphology of PS-CS membranes was shown by scanning electron microscopy (SEM) to have an interconnected porous structure. The incorporation of phosphoserine into chitosan membranes was confirmed by energy dispersive spectrum (EDS), Fourier Transforms Infrared (FTIR), and X-ray diffraction (XRD) spectrum. The CCK8 assay and Live/Dead staining, Hemolysis analysis, and cell adhesion assay demonstrated that PS-CS membranes had good biocompatibility. The osteogenesis-related gene expression of BMSCs was higher in PS-CS membranes than in CS membranes, which was verified by alkaline phosphatase (ALP) activity, immunofluorescence staining, and real-time quantitative PCR (RT-qPCR). Furthermore, micro-CT and histological analysis of rat cranial bone defect demonstrated that PS-CS membranes dramatically stimulated bone regeneration in vivo. Moreover, H&E staining of the main organs (heart, liver, spleen, lung, or kidney) showed no obvious histological abnormalities, revealing that PS-CS membranes were no additional systemic toxicity in vivo. Collectively, PS-CS membranes may be a promising candidate for bone tissue engineering.

Bioactivity Potential of Bioceramic-Based Root Canal Sealers: A Scoping Review

INTRODUCTION

Bioceramic-based root canal sealers are novel materials with a bioactivity potential that stands out compared with conventional root canal sealers. However, the term bioactivity may be overused and is often misunderstood. Hence, the objective of this study was to synthesize and map key concepts related to the bioactivity analysis of bioceramic-based root canal sealers.

METHODS

The present scoping review is reported in accordance with the PRISMA-ScR Statement and is registered in the Open Science Framework. Two blinded reviewers carried out a comprehensive search in six databases up to January 10th, 2022: MEDLINE, Scopus, Embase, Web of Science, Cochrane Library, and Lilacs/BBO. Eligibility was considered for in vitro and in vivo studies that evaluated the bioactivity potential of bioceramic-based root canal sealers.

RESULTS

A total of 53 studies were included in the qualitative synthesis. In vitro bioactivity was evaluated through the mineralization potential, formation of carbonated apatite on the surface, and the gene expression related to proteins involved in the mineralization process. Meanwhile, for in vivo studies, staining techniques associated with immunohistochemical tests were mainly used to detect mineralization on the material-host tissue interface.

CONCLUSIONS

According to the methodology used, the most prevalent methods to assess bioactivity in acellular form were the immersion of the material in Hank's balanced salt solution, followed by surface observation with scanning electron microscopy and energy dispersive X-ray. In cell cultures, the chosen method was usually Alizarin Red staining, followed by the evaluation of alkaline phosphatase enzymatic activity and the use of molecular biology tests.

Biological Evaluation of the Effect of Root Canal Sealers Using a Rat Model

Gutta-percha points and root canal sealers have been used for decades in endodontics for root canal obturation. With techniques such as single cone methods, the amount of sealer is larger, making their properties more critical. However, relatively few reports have comprehensively evaluated their biological effects. To this end, we evaluated three types of sealers, zinc oxide-fatty acid-, bio-glass- and methacrylate resin-containing sealers were considered. Their biological effects were evaluated using a rat subcutaneous implantation model. Each sealer was loaded inside a Teflon tube and implanted subcutaneously in the backs of rats. Inflammatory cells were observed around all samples 7 days after implantation and reduced after 28 days. Our results revealed that all samples were in contact with the subcutaneous tissue surrounding the sealer. Additionally, Ca and P accumulation was observed in only the bio-glass-containing sealer. Furthermore, each of the three sealers exhibited unique immune and inflammatory modulatory effects. In particular, bio-glass and methacrylate resin sealers were found to induce variable gene expression in adjacent subcutaneous tissues related to angiogenesis, wound healing, muscle tissue, and surrounding subcutaneous tissue. These results may help to understand the biological impacts of root canal sealers on surrounding biological tissues, guiding future research and comparisons with new generations of materials.