Effects of Recombinant Overexpression of Bcl2 on the Proliferation, Apoptosis, and Osteogenic/Odontogenic Differentiation Potential of Dental Pulp Stem Cells

Role of Pyrrolidine dithiocarbamate in inducing odontoblastic differentiation of dental pulp stem cells

Background

Pyrrolidine dithiocarbamate (PDTC) is an efficient, reproducible, and biological antioxidant of clinical utility, which may also be preferred for obtaining human dental pulp stem cells (hDPSCs) for the purpose of tissue engineering and regenerative medicine.

Aim and Objectives

The study was conducted to evaluate the effects of PDTC on the propagation and differentiation of hDPSCs.

Materials and Methods

hDPSCs were isolated by explant culture method and characterized for stem cell properties using flow cytometry method. The effects of PDTC-induced odontoblastic differentiation of hDPSC at different concentrations (0.5, 1.0, and 5.0 mM) were determined by staining for mineralization.

Results

Mineralization was more prominent and significantly higher in the induced hDPSCs treated with 1.0 mM concentration of PDTC.

Conclusion

PDTC at 1.0 mM concentration could have a significant pharmacological role in activating and enhancing odontogenic differentiation of dental stem cells and make it an important step in regenerative dentistry.

Applications of Graphene Family Nanomaterials in Regenerative Medicine: Recent Advances, Challenges, and Future Perspectives

Graphene family nanomaterials (GFNs) have attracted considerable attention in diverse fields from engineering and electronics to biomedical applications because of their distinctive physicochemical properties such as large specific surface area, high mechanical strength, and favorable hydrophilic nature. Moreover, GFNs have demonstrated the ability to create an anti-inflammatory environment and exhibit antibacterial effects. Consequently, these materials hold immense potential in facilitating cell adhesion, proliferation, and differentiation, further promoting the repair and regeneration of various tissues, including bone, nerve, oral, myocardial, and vascular tissues. Note that challenges still persist in current applications, including concerns regarding biosecurity risks, inadequate adhesion performance, and unsuitable degradability as matrix materials. This review provides a comprehensive overview of current advancements in the utilization of GFNs in regenerative medicine, as well as their molecular mechanism and signaling targets in facilitating tissue repair and regeneration. Future research prospects for GFNs, such as potential in promoting ocular tissue regeneration, are also discussed in details. We hope to offer a valuable reference for the clinical application of GFNs in the treatment of bone defects, nerve damage, periodontitis, and atherosclerosis.

Priming strategies for controlling stem cell fate: Applications and challenges in dental tissue regeneration

Mesenchymal stromal cells (MSCs) have attracted intense interest in the field of dental tissue regeneration. Dental tissue is a popular source of MSCs because MSCs can be obtained with minimally invasive procedures. MSCs possess distinct inherent properties of self-renewal, immunomodulation, proangiogenic potential, and multilineage potency, as well as being readily available and easy to culture. However, major issues, including poor engraftment and low survival rates in vivo, remain to be resolved before large-scale application is feasible in clinical treatments. Thus, some recent investigations have sought ways to optimize MSC functions in vitro and in vivo. Currently, priming culture conditions, pretreatment with mechanical and physical stimuli, preconditioning with cytokines and growth factors, and genetic modification of MSCs are considered to be the main strategies; all of which could contribute to improving MSC efficacy in dental regenerative medicine. Research in this field has made tremendous progress and continues to gather interest and stimulate innovation. In this review, we summarize the priming approaches for enhancing the intrinsic biological properties of MSCs such as migration, antiapoptotic effect, proangiogenic potential, and regenerative properties. Challenges in current approaches associated with MSC modification and possible future solutions are also indicated. We aim to outline the present understanding of priming approaches to improve the therapeutic effects of MSCs on dental tissue regeneration.

The Role of miR-34c-5p in Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells

Background and Objectives

Osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) plays a critical role in the success of lumbar spinal fusion with autogenous bone graft. This study aims to explore the role and specific mechanism of miR-34c-5p in osteogenic differentiation of BMSCs.

Methods and Results

Rabbit model of lumbar fusion was established by surgery. The osteogenic differentiation dataset of mesenchymal stem cells was obtained from the Gene Expression Omnibus (GEO) database, and differentially expressed miRNAs were analyzed using R language (limma package). The expressions of miR-34c-5p, miR-199a-5p, miR-324-5p, miR-361-5p, RUNX2, OCN and Bcl-2 were determined by qRT-PCR and Western blot. ELISA, Alizarin red staining and CCK-8 were used to detect the ALP content, calcium deposition and proliferation of BMSCs. The targeted binding sites between miR-34c-5p and Bcl-2 were predicted by the Target database and verified using dual-luciferase reporter assay. MiR-34c-5p expression was higher in rabbit lumbar fusion model and differentiated BMSCs than normal rabbit or BMSCs. The content of ALP and the deposition of calcium increased with the osteogenic differentiation of BMSCs. Upregulation of miR-34c-5p reduced cell proliferation and promoted ALP content, calcium deposition, RUNX2 and OCN expression compared with the control group. The effects of miR-34c-5p inhibitor were the opposite. In addition, miR-34c-5p negatively correlated with Bcl-2. Upregulation of Bcl-2 reversed the effects of miR-34c-5p on ALP content, calcium deposition, and the expressions of RUNX2 and OCN.

Conclusions

miR-34c-5p could promote osteogenic differentiation and suppress proliferation of BMSCs by inhibiting Bcl-2.

Bcl-2 Overexpression and Hypoxia Synergistically Enhance Angiogenic Properties of Dental Pulp Stem Cells

Post-implantation cell survival and angio-/vasculogenesis are critical for the success of cell-based regenerative strategies. The current study aimed to overexpress B-cell lymphoma 2 (Bcl-2) gene in dental pulp stem cells (DPSCs) and examine the anti-apoptotic and angio-/vasculogenic effects both in-vitro and in-vivo. DPSCs were transduced with Bcl-2-green fluorescent protein (GFP) lentiviral particles and examined for cell proliferation and apoptosis. The cells were cultured under normoxic or hypoxic (0.5 mM CoCl₂) conditions and examined for the expression of angiogenic factors and effects on endothelial cell proliferation, migration and vessel morphogenesis. Cells with or without hypoxic preconditioning were used in in-vivo Matrigel plug assay to study the post-implantation cell survival and angio-/vasculogenesis. Bcl-2-overexpressing-DPSCs showed significantly lower apoptosis than that of null-GFP-DPSCs under serum-free conditions. Under hypoxia, Bcl-2-overexpressing-DPSCs expressed significantly higher levels of vascular endothelial growth factor compared to that under normoxia and null-GFP-DPSCs. Consequently, Bcl-2-overexpressing-DPSCs significantly enhanced endothelial cell proliferation, migration and vascular tube formation on Matrigel. Immunohistological assessment of in-vivo transplanted Matrigel plugs showed significantly higher cell survival and vasculature in hypoxic preconditioned Bcl-2-overexpressing-DPSC group compared to null-GFP-DPSC group. In conclusion, Bcl-2 overexpression and hypoxic-preconditioning could be synergistically used to enhance post-implantation cell survival and angio-/vasculogenic properties of DPSCs.

A mussel-inspired osteogenesis microenvironment with bioactive peptides for the dual-functionalization of biomedical substrates

A facile but useful peptide modified strategy for the dual-functionalization of biomedical implants with cell-adhesion-enhancing as well as differentiation-inducing abilities.

Fusobacterium nucleatum Facilitates Apoptosis, ROS Generation, and Inflammatory Cytokine Production by Activating AKT/MAPK and NF-κB Signaling Pathways in Human Gingival Fibroblasts

Fusobacterium nucleatum (F. nucleatum) plays key roles in the initiation and progression of periodontitis. However, the pathogenic effect of F. nucleatum on human oral tissues and cells has not been fully evaluated. In this study, we aimed to analyze the pathogenic effects of F. nucleatum on human gingival fibroblasts (GFs) and clarify the potential mechanisms. RNA-sequencing analysis confirmed that F. nucleatum significantly altered the gene expression of GF as the stimulation time increased. Cell counting and EdU-labeling assays indicated that F. nucleatum inhibited GF proliferation and promoted cell apoptosis in a time- and dose-dependent manner. In addition, cell apoptosis, intracellular reactive oxygen species (ROS) generation, and proinflammatory cytokine production were dramatically elevated after F. nucleatum stimulation. Furthermore, we found that the AKT/MAPK and NF-κB signaling pathways were significantly activated by F. nucleatum infection and that a large number of genes related to cellular proliferation, apoptosis, ROS, and inflammatory cytokine production downstream of AKT/MAPK and NF-κB signaling pathways were significantly altered in F. nucleatum-stimulated GFs. These findings suggest that F. nucleatum inhibits GF proliferation and promotes cell apoptosis, ROS generation, and inflammatory cytokine production partly by activating the AKT/MAPK and NF-κB signaling pathways. Our study opens a new window for understanding the pathogenic effects of periodontal pathogens on the host oral system.

Dental pulp stem cells overexpressing stromal-derived factor-1α and vascular endothelial growth factor in dental pulp regeneration

OBJECTIVES

The current study aimed to investigate the effects of vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1α (SDF-1α) overexpressing dental pulp stem cells (DPSCs) in vascularized dental pulp regeneration in vivo.

MATERIALS AND METHODS

Human DPSCs were transfected with VEGF or SDF-1α using premade lentiviral particles. Overexpression was verified by quantitative polymerase chain reaction (q-PCR), enzyme-linked immunosorbent assay (ELISA), and western blot analysis. Effects of SDF-1α and VEGF overexpressing DPSCs on their proliferation (CCK-8 and MTT assays) and endothelial vascular-tube formation (Matrigel assay) were investigated in vitro. Human tooth roots sectioned into 6-mm segments were injected with gene-modified DPSCs encapsulated in PuraMatrix hydrogel and implanted in the dorsum of severe-combined-immunodeficient (SCID) mice. Implants were retrieved after 4 weeks and examined for regenerated pulp-like tissue and vascularization using histology and immunohistochemistry. p < 0.05 was considered statistically significant.

RESULTS

Gene-modified DPSCs expressed significantly high levels (p < 0.05) of SDF-1α and VEGF mRNA and proteins, respectively. Transfected DPSCs showed a significantly higher cell proliferation compared to that of wild-type DPSCs. Furthermore, they enhanced endothelial cell migration and vascular-tube formation on Matrigel in vitro. When injected into tooth root canals and implanted in vivo, DPSCs/SDF-1α + DPSCs/VEGF-mixed group resulted in significantly increased length of regenerated pulp-like tissue within the root canals compared to that of wild-type DPSCs/VEGF and DPSCs/SDF-1α groups. Vessel area density was significantly higher in DPSCs/SDF-1α and mixed DPSCs/SDF-1α + DPSCs/VEGF groups than in DPSCs-VEGF alone or wild-type DPSCs groups.

CONCLUSION

A combination of VEGF-overexpressing and SDF-1α-overexpressing DPSCs could enhance the area of vascularized dental pulp regeneration in vivo.

CLINICAL RELEVANCE

Enhancing vascularization in pulp regeneration is crucial to overcome the clinical limitation of the limited blood supply to the root canals via a small apical foramen enclosed by hard dentin.

Dental pulp stem cells and osteogenesis: an update

Dental pulp stem cells constitute an attractive source of multipotent mesenchymal stem cells owing to their high proliferation rate and multilineage differentiation potential. Osteogenesis is initiated by osteoblasts, which originate from mesenchymal stem cells. These cells express specific surface antigens that disappear gradually during osteodifferentiation. In parallel, the appearance of characteristic markers, including alkaline phosphatase, collagen type I, osteocalcin and osteopontin characterize the osteoblastic phenotype of dental pulp stem cells. This review will shed the light on the osteogenic differentiation potential of dental pulp stem cells and explore the culture medium components, and markers associated with osteodifferentiation of these cells.

Effect of tetrahedral DNA nanostructures on proliferation and osteo/odontogenic differentiation of dental pulp stem cells via activation of the notch signaling pathway

Dental pulp stem cells (DPSCs) derived from the human dental pulp tissue have multiple differentiation capabilities, such as osteo/odontogenic differentiation. Therefore, DPSCs are deemed as ideal stem cell sources for tissue regeneration. As new nanomaterials based on DNA, tetrahedral DNA nanostructures (TDNs) have tremendous potential for biomedical applications. Here, the authors aimed to explore the part played by TDNs in proliferation and osteo/odontogenic differentiation of DPSCs, and attempted to investigate if these cellular responses could be driven by activating the canonical Notch signaling pathway. Upon exposure to TDNs, proliferation and osteo/odontogenic differentiation of DPSCs were dramatically enhanced, accompanied by up regulation of Notch signaling. In general, our study suggested that TDNs can significantly promote proliferation and osteo/odontogenic differentiation of DPSCs, and this remarkable discovery can be applied in tissue engineering and regenerative medicine to develop a significant and novel method for bone and dental tissue regeneration.

Pulpal Tissue Inflammatory Reactions after Experimental Pulpal Exposure in Mice

INTRODUCTION

The purpose of this study was to establish a stable experimental mice pulpal inflammatory model and to evaluate inflammatory reactions of pulpal tissue after pulpal exposure.

METHODS

Pulpal inflammation was induced in 80 C57BL/6 mice by occlusal exposure of the pulp of the maxillary first molar. The mice were sacrificed randomly at 0, 1, 6, 12, 24, 48, and 72 hours after pulpal exposure. Mice without pulpal exposure served as controls. Maxillary teeth were obtained and prepared for histologic analyses and real-time polymerase chain reaction analyses.

RESULTS

As the duration of pulpal exposure increases, the inflammatory reaction is exacerbated. Within 6 to 12 hours after pulpal exposure, pulp tissues experienced red blood cell extravasation to the destruction of the odontoblast layer. After 24 hours, necrosis was observed in the pulpal tissue; until 72 hours, necrosis spread to the whole coronal pulpal tissue, and a large number of inflammatory cells were found in the radicular pulpal tissue. The results of histomorphologic scores have the same trend; samples from the 72-hour group possessed the highest score followed by samples from other groups (P < .01). The expression levels of inflammatory cytokines increased over the 72 hours, and there was a high rate of inflammatory cytokine expression at 6 and 12 hours after pulpal exposure.

CONCLUSIONS

Our study represents a stable mice model for studying pulpal inflammation in vivo. Mouse pupal inflammation progresses rapidly, with dramatic changes evident in just a few hours.