In cases of pulp exposure due to deep dental caries or severe traumatic injuries, existing pulp-capping materials have a limited ability to reconstruct dentin-pulp complexes and can result in pulpectomy because of their low potentials to accelerate dental pulp cell activities, such as migration, proliferation, and differentiation. Therefore, the development of more effective therapeutic agents has been anticipated for direct pulp capping. Dental pulp tissues are enriched with dental pulp stem cells (DPSCs). Here, the authors investigated the effects of semaphorin 3A (Sema3A) on various functions of human DPSCs in vitro and reparative dentin formation in vivo in a rat dental pulp exposure model. Immunofluorescence staining revealed expression of Sema3A and its receptor Nrp1 (neuropilin 1) in rat dental pulp tissue and human DPSC clones. Sema3A induced cell migration, chemotaxis, proliferation, and odontoblastic differentiation of DPSC clones. In addition, Sema3A treatment of DPSC clones increased β-catenin nuclear accumulation, upregulated expression of the FARP2 gene (FERM, RhoGEF, and pleckstrin domain protein 2), and activated Rac1 in DPSC clones. Furthermore, in the rat dental pulp exposure model, Sema3A promoted reparative dentin formation with dentin tubules and a well-aligned odontoblast-like cell layer at the dental pulp exposure site and with novel reparative dentin almost completely covering pulp tissue at 4 wk after direct pulp capping. These findings suggest that Sema3A could play an important role in dentin regeneration via canonical Wnt/β-catenin signaling. Sema3A might be an alternative agent for direct pulp capping, which requires further study.

IntroductionThe 3-dimensional scaffold plays a key role in volume and quality of repair tissue in periodontal tissue engineering therapy. We fabricated a novel 3D collagen scaffold containing carbon-based 2-dimensional layered material, named graphene oxide (GO). The aim of this study was to characterize and assess GO scaffold for periodontal tissue healing of class II furcation defects in dog.Materials and methodsGO scaffolds were prepared by coating the surface of a 3D collagen sponge scaffold with GO dispersion. Scaffolds were characterized using cytotoxicity and tissue reactivity tests. In addition, GO scaffold was implanted into dog class II furcation defects and periodontal healing was investigated at 4 weeks postsurgery.ResultsGO scaffold exhibited low cytotoxicity and enhanced cellular ingrowth behavior and rat bone forming ability. In addition, GO scaffold stimulated healing of dog class II furcation defects. Periodontal attachment formation, including alveolar bone, periodontal ligament-like tissue, and cementum-like tissue, was significantly increased by GO scaffold implantation, compared with untreated scaffold.ConclusionThe results suggest that GO scaffold is biocompatible and possesses excellent bone and periodontal tissue formation ability. Therefore, GO scaffold would be beneficial for periodontal tissue engineering therapy.

We present serial changes on diffusion-weighted MRI (DWI) in a patient with Creutzfeldt-Jakob disease (CJD). DWI revealed serial changes of abnormal hyperintense lesions that had become more extensive and conspicuous with progression of neurologic findings, more sensitively than conventional MRI. In the late stage, disappearance of abnormal hyperintense lesions on DWI was observed. DWI proved to be particularly useful for monitoring the progression of CJD.

Japan Running titlePeriodontal healing by nano β-TCP and FGF-2 Key wordsPeriodontal tissue engineering, Fibroblast growth factor-2 (FGF-2), β-tricalcium phosphate

Kosen Y, Miyaji H, Kato A, Sugaya T, Kawanami M. Application of collagen hydrogel/sponge scaffold facilitates periodontal wound healing in class II furcation defects in beagle dogs. J Periodont Res 2012; 47: 626–634. © 2012 John Wiley & Sons A/S Background and Objective:  A three‐dimensional scaffold may play an important role in periodontal tissue engineering. We prepared bio‐safe collagen hydrogel, which exhibits properties similar to those of native extracellular matrix. The aim of this study was to examine the effect of implantation of collagen hydrogel/sponge scaffold on periodontal wound healing in class II furcation defects in dogs. Material and Methods:  The collagen hydrogel/sponge scaffold was prepared by injecting collagen hydrogel, cross‐linked to the ascorbate‐copper ion system, into a collagen sponge. Class II furcation defects (of 5 mm depth and 3 mm width) were surgically created in beagle dogs. The exposed root surface was planed and demineralized with EDTA. In the experimental group, the defect was filled with collagen hydrogel/sponge scaffold. In the control group, no implantation was performed. Histometric parameters were evaluated 2 and 4 wk after surgery. Results:  At 2 wk, the collagen hydrogel/sponge scaffold displayed high biocompatibility and biodegradability with numerous cells infiltrating the scaffold. In the experimental group, reconstruction of alveolar bone and cementum was frequently observed 4 wk after surgery. Periodontal ligament tissue was also re‐established between alveolar bone and cementum. Volumes of new bone, new cementum and new periodontal ligament were significantly greater in the experimental group than in the control group. In addition, epithelial down‐growth was suppressed by application of collagen hydrogel. Conclusion:  The collagen hydrogel/sponge scaffold possessed high tissue compatibility and degradability. Implantation of the scaffold facilitated periodontal wound healing in class II furcation defects in beagle dogs.

Carbon-based nanomaterials are being investigated for biomedical applications. Graphene oxide (GO), a monolayer of carbon, holds promise as a tissue engineering substrate due to its unique physicochemical properties. The aim of this study was to evaluate the effect of a GO coating on cell proliferation and differentiation in vitro. We also assessed the bioactivities of collagen scaffolds coated with different concentrations of GO in rats. The results showed that GO affects both cell proliferation and differentiation, and improves the properties of collagen scaffolds. Subcutaneous implant tests showed that low concentrations of GO scaffold enhances cell in-growth and is highly biodegradable, whereas high concentrations of GO coating resulted in adverse biological effects.Consequently, scaffolds modified with a suitable concentration of GO are useful as a bioactive material for tissue engineering.

Nanoparticle bioceramics have become anticipated for biomedical applications. Highly bioactive and biodegradable scaffolds would be developed using nanoparticles of -tricalcium phosphate ( -TCP). We prepared collagen scaffolds coated by nano--TCP and fibroblast growth factor 2 (FGF2) and evaluated the effects on new bone augmentation and biodegradation. The collagen sponge was coated with the nano-TCP dispersion and freeze-dried. Scaffold was characterized by SEM, TEM, XRD, compressive testing and cell seeding. Subsequently, the nano--TCP/collagen scaffold, collagen sponge, and each material loaded with FGF2 were implanted on rat cranial bone. As a control, no implantation was performed. Nano-TCP particles were found to be attached to the fibers of the collagen sponge by SEM and TEM observations. Scaffold coated with nano-TCP showed higher compressive strength and cytocompatibility. In histological evaluations at 10 days, inflammatory cells were rarely seen around the residual scaffold, suggesting that the nano-TCP material possesses good tissue compatibility. At 35 days, bone augmentation and scaffold degradation in histological samples receiving nano--TCP scaffold were significantly greater than those in the control. By loading of FGF2, advanced bone formation is facilitated, indicating that a combination with FGF2 would be effective for bone tissue engineering.

Great efforts have been devoted to the exploration of potential diagnostic and therapeutic applications of thiolate-protected gold nanoclusters (Au NCs). One of the therapeutic applications is the photosensitized generation of highly reactive singlet oxygen (1O2) using Au NCs for photodynamic therapy. However, there is scope for improving the 1O2-generation efficiency of Au NC photosensitizers. In this study, we exploit three strategies to improve the 1O2-generation efficiency of glutathione-protected Au NCs: (i) doping with silver (i.e., using bimetallic AuAg NCs, (ii) achieving aggregation-induced emission (AIE) using a Au­(I)–thiolate complex, and (iii) achieving self-assembly-induced emission (SAIE) using a polymer nanogel. The combination of these three effects dramatically increased the 1O2-generation efficiency and enhanced the luminescence of the glutathione-protected Au NCs, owing to the inhibition of the nonradiative decay pathways. Finally, the photosensitizers based on AuAg NC@nanogel composites were successfully used for antimicrobial photodynamic therapy (a-PDT) against oral bacteria. This study provides general insights into the molecular design of water-soluble Au NC photosensitizers for therapeutic applications.