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.

[Adhesion of Streptococcus mutans to removable denture crowns].

OBJECTIVE: To determine adhesion of Streptococcus mutans (S. mutans) to different kinds of removable denture crowns for the purpose of minimizing influence of removable denture on oral environment. METHODS: Three kinds of removable denture crowns (single color synthetic resin teeth, alloy pin porcelain tooth and minute color synthetic resin teeth) were adsorbed S. mutans for 24 h in sterile saliva, The adhered bacteria were counted by means of sonic oscillation and bacteria coating. RESULTS: Highest level of adhesion was found on ,the single color synthetic resin teeth was adsorbed mostly, followed by alloy pin porcelain teeth. Minute color synthetic resin teeth had far less adhesion than the others (P<0.01). CONCLUSION: Minute color synthetic resin teeth have less adhesion of S. mutans, which may be associated with their lower level of surface free energy.

Comparing Bone Alteration and Esthetic Recovery Between the Socket-Shield Technique and the Conventional Immediate Implant Technique: A Retrospective Study.

PURPOSE: To evaluate bone preservation and esthetic recovery between the socket-shield technique (SST) with different labial bone plate thicknesses and the conventional immediate implant technique (CIIT). MATERIALS AND METHODS: Patients who underwent immediate implant placement in the anterior region were divided into three groups: the SST with a thickwall phenotype (> 1 mm; SSTA group), the SST with a thin-wall phenotype (< 1 mm; SSTB group), and the CIIT with a thickwall phenotype (> 1 mm; CIIT group). Radiologic images and clinical photos were collected before surgery, immediately postoperatively, and 6 months postoperatively. The labial bone width, labial bone width change (BWC), labial bone volume change (BVC), pink esthetic score (PES), and complication rate were evaluated among the three groups. Statistical analysis was performed using SPSS software. RESULTS: A total of 60 patients (n = 20/group) were enrolled in this 6-month retrospective study. The BWC in the SSTA group (0.22 to 0.30 mm) and the SSTB group (0.18 to 0.33 mm) was less than that in the CIIT group (0.61 to 0.80 mm; P < .004). The SSTA group and the SSTB group had a lower BVC (24.08 vs 21.14 vs 54.81, respectively; P = .004) and greater PES (11.75 vs 11.65 vs 10.65, respectively; P = .009) than the CIIT group. No complications occurred among these patients. CONCLUSIONS: With the limitations of this study, it can be concluded that the SST is a reliable method for preserving bone and achieving satisfactory esthetic outcomes. The labial bone plate phenotype associated with the SST has minimal impact on both clinical and radiologic outcomes.

Hypoxia Drives Material-Induced Heterotopic Bone Formation by Enhancing Osteoclastogenesis via M2/Lipid-Loaded Macrophage Axis.

Heterotopic ossification (HO) is a double-edged sword. Pathological HO presents as an undesired clinical complication, whereas controlled heterotopic bone formation by synthetic osteoinductive materials shows promising therapeutic potentials for bone regeneration. However, the mechanism of material-induced heterotopic bone formation remains largely unknown. Early acquired HO being usually accompanied by severe tissue hypoxia prompts the hypothesis that hypoxia caused by the implantation coordinates serial cellular events and ultimately induces heterotopic bone formation in osteoinductive materials. The data presented herein shows a link between hypoxia, macrophage polarization to M2, osteoclastogenesis, and material-induced bone formation. Hypoxia inducible factor-1α (HIF-1α), a crucial mediator of cellular responses to hypoxia, is highly expressed in an osteoinductive calcium phosphate ceramic (CaP) during the early phase of implantation, while pharmacological inhibition of HIF-1α significantly inhibits M2 macrophage, subsequent osteoclast, and material-induced bone formation. Similarly, in vitro, hypoxia enhances M2 macrophage and osteoclast formation. Osteoclast-conditioned medium enhances osteogenic differentiation of mesenchymal stem cells, such enhancement disappears with the presence of HIF-1α inhibitor. Furthermore, metabolomics analysis reveals that hypoxia enhances osteoclastogenesis via the axis of M2/lipid-loaded macrophages. The current findings shed new light on the mechanism of HO and favor the design of more potent osteoinductive materials for bone regeneration.

Design, fabrication and applications of tetrahedral DNA nanostructure-based multifunctional complexes in drug delivery and biomedical treatment.

Although organic nanomaterials and inorganic nanoparticles possess inherent flexibility, facilitating functional modification, increased intracellular uptake and controllable drug release, their underlying cytotoxicity and lack of specificity still cause safety concerns. Owing to their merits, which include natural biocompatibility, structural stability, unsurpassed programmability, ease of internalization and editable functionality, tetrahedral DNA nanostructures show promising potential as an alternative vehicle for drug delivery and biomedical treatment. Here, we describe the design, fabrication, purification, characterization and potential biomedical applications of a self-assembling tetrahedral DNA nanostructure (TDN)-based multifunctional delivery system. First, relying on Watson-Crick base pairing, four single DNA strands form a simple and typical pyramid structure via one hybridization step. Then, the protocol details four different modification approaches, including replacing a short sequence of a single DNA strand by an antisense peptide nucleic acid, appending an aptamer to the vertex, direct incubation with small-molecular-weight drugs such as paclitaxel and wogonin and coating with protective agents such as cationic polymers. These modified TDN-based complexes promote the intracellular uptake and biostability of the delivered molecules, and show promise in the fields of targeted therapy, antibacterial and anticancer treatment and tissue regeneration. The entire duration of assembly and characterization depends on the cargo type and modification method, which takes from 2 h to 3 d.

Stiffness regulates the proliferation and osteogenic/odontogenic differentiation of human dental pulp stem cells via the WNT signalling pathway.

OBJECTIVES: Researches showed that stiffness of the extracellular matrix can affect the differentiation of many stem cells. Dental pulp stem cells (DPSCs) are a promising type of adult stem cell. However, we know little about whether and how the behaviour of DPSCs is influenced by stiffness. MATERIALS AND METHODS: We carried out a study that cultured DPSCs on tunable elasticity polydimethylsiloxane substrates to investigate the influence on morphology, proliferation, osteogenic/odontogenic differentiation and its possible mechanism. RESULTS: Soft substrates changed the cell morphology and inhibited the proliferation of DPSCs. Expression of markers related to osteogenic/odontogenic differentiation was significantly increased as the substrate stiffness increased, including ALP (alkaline phosphatase), OCN (osteocalcin), OPN (osteopontin), RUNX-2 (runt-related transcription factor-2), BMP-2 (bone morphogenetic protein-2), DSPP (dentin sialophosphoprotein) and DMP-1 (dentin matrix protein-1). Mechanical properties promote the function of DPSCs related to the Wnt signalling pathway. CONCLUSIONS: Our results showed that mechanical factors can regulate the proliferation and differentiation of DPSCs via the WNT signalling pathway. This provides theoretical basis to optimize dental or bone tissue regeneration through increasing stiffness of extracelluar matrix.