A randomized controlled clinical evaluation of desensitization efficacy of a newly developed toothpaste with highly stabilized SnF2.

PURPOSE: To assess the relief of dentin hypersensitivity of the new toothpaste with stabilized stannous fluoride (SnF2) versus a marketed standard fluoride toothpaste as a negative control and a marketed anhydrous SnF2 toothpaste as a positive control. METHODS: This was a single-centered, randomized, controlled, double blind, clinical trial. 96 participants with hypersensitivity were enrolled in this 4-week clinical study. Electrical stimulation and evaporative air tests were performed to evaluate the desensitization efficacy. Clinical assessments were made at baseline, and after 3 days, 1 week, 2 weeks and 4 weeks of twice-daily brushing. Additionally, the influence of Sn² ⁺ species on desensitization was evaluated using bovine dentin specimens treated with toothpaste. RESULTS: All 96 enrolled participants were randomized. 96 participants completed all evaluations. Participants had an average age (SD) of 47.0 (10.5) years; 45% of participants were female. Both SnF2 toothpastes showed superior desensitization efficacy compared to the negative control toothpaste, the conventional sodium monofluorophosphate (SMFP) toothpaste, after a week. The new stabilized SnF2 toothpaste demonstrated improved electrical stimulation benefits compared to the negative control toothpaste, with increases of 15.1% after 3 days, 34.2% after 1 week, 66.3% after 2 weeks, and 111.6% after 4 weeks. Additionally, it showed relative verbal evaluation scale (VES) benefits of 14.2% after 3 days, 37.6% after 1 week, 28.9% after 2 weeks, and 37.4% after 4 weeks. The stabilized SnF2 toothpaste exhibited desensitization properties comparable to those of a commercial anhydrous SnF2 toothpaste, which typically produces undesirable side effects in the mouth. Toothpastes containing 0.454 % SnF2 exhibited perfect occlusion of dentin tubules. CLINICAL SIGNIFICANCE: The stabilized 0.454% SnF2 toothpaste exhibited significantly greater dentin hypersensitivity relief within only a week and comparable property to commercial anhydrous SnF2 toothpaste.

Spatially Assembled Bilayer Cell Sheets of Stem Cells and Endothelial Cells Using Thermosensitive Hydrogels for Therapeutic Angiogenesis.

Although the coculture of multiple cell types has been widely employed in regenerative medicine, in vivo transplantation of cocultured cells while maintaining the hierarchical structure remains challenging. Here, a spatially assembled bilayer cell sheet of human mesenchymal stem cells and human umbilical vein endothelial cells on a thermally expandable hydrogel containing fibronectin is prepared and its effect on in vitro proangiogenic functions and in vivo ischemic injury is investigated. The expansion of hydrogels in response to a temperature change from 37 to 4 °C allows rapid harvest and delivery of the bilayer cell sheet to two different targets (an in vitro model glass surface and in vivo tissue). The in vitro study confirms that the bilayer sheet significantly increases proangiogenic functions such as the release of nitric oxide and expression of vascular endothelial cell genes. In addition, transplantation of the cell sheet from the hydrogels into a hindlimb ischemia mice model demonstrates significant retardation of necrosis particularly in the group transplated with the bilayer sheet. Collectively, the bilayer cell sheet is readily transferrable from the thermally expandable hydrogel and represents an alternative approach for recovery from ischemic injury, potentially via improved cell-cell communication.

Delivery of a Cell Patch of Cocultured Endothelial Cells and Smooth Muscle Cells Using Thermoresponsive Hydrogels for Enhanced Angiogenesis.

Cell-based therapy has been studied as an attractive strategy for therapeutic angiogenesis. However, obtaining a stable vascular structure remains a challenge due to the poor interaction of transplanted cells with native tissue and the difficulty in selecting the optimal cell source. In this study, we developed a cell patch of cocultured human umbilical vein endothelial cells (HUVECs) and smooth muscle cells (SMCs) using thermosensitive hydrogels for regeneration of mature vasculatures. In vitro characterization of HUVECs in the cocultured group revealed the formation of a mesh-like morphology over 5 days of culture. Vascular endothelial growth factor expression was also upregulated in the cocultured group compared with HUVECs only. The cell patch seeded with HUVECs, SMCs, or both cell type was prepared on the synthetic thermosensitive and cell interactive hydrogels, and readily detached from the hydrogel within 10 min by expansion of the hydrogel when the temperature was decreased to 4°C. We then investigated the therapeutic effect of the cell patch using a hind limb ischemic model of an athymic mouse. Overall, the group that received a cell patch of cocultured HUVECs and SMCs had a significantly retarded rate of necrosis with a significant increase in the number of arterioles and capillaries for 4 weeks compared with the groups transplanted with only HUVECs or SMCs. Dual staining of smooth muscle alpha actin and human nuclear antigen showed that the implanted cell patch was partially involved in vessel formation. In summary, the simple transplantation of a cocultured cell patch using a hydrogel system could enhance therapeutic angiogenesis through the regeneration of matured vascular structures.

Construction of 3-D Cellular Multi-Layers with Extracellular Matrix Assembly Using Magnetic Nanoparticles.

Construction of 3-dimensional (3-D) engineered tissue is increasingly being investigated for use in drug discovery and regenerative medicine. Here, we developed multi-layered 3-D cellular assembly by using magnetic nanoparticles (MNP) isolated from Magnetospirillum sp. AMB-1 magnetotactic bacteria. Magnetized human dermal fibroblasts (HDFBs) were prepared by treatment with the MNP, induced to form 3-D assembly under a magnetic field. Analyses including LIVE/DEAD assay, transmission electron microscopy revealed that the MNP were internalized via clathrin-mediated endocytosis without cytotoxicity. The magnetized HDFBs could build 3-D structure as a function of seeding density. When the highest seeding density (5 × 105 cells/mm2 was used, the thickness of assembly was 41.90 ± 1.69 µm, with approximately 9.3 ± 1.6 cell layers being formed. Immunofluorescence staining confirmed homogeneous distribution of ECM and junction proteins throughout the 3-D assembly. Real-time PCR analysis showed decrease in expression levels of collagen types I and IV but increase in that of connexin 43 in the 3-D assembly compared with the 2-D culture. Finally, we demonstrated that the discernible layers can be formed hierarchically by serial assembly. In conclusion, our study showed that a multi-layered structure can be easily prepared using magnetically-assisted cellular assembly with highlighting cell-cell and cell-ECM communication.

Reconstruction of vascular structure with multicellular components using cell transfer printing methods.

Natural vessel has three types of concentric cell layers that perform their specific functions. Here, the fabrication of vascular structure is reported by transfer printing of three different cell layers using thermosensitive hydrogels. Tetronic-tyramine and RGD peptide are co-crosslinked to prepare cell adhesive and thermosensitive hydrogels. The hydrogel increases its diameter by 1.26 times when the temperature reduces from 37 °C to 4 °C. At optimized seeding density, three types of cells form monolayers on the hydrogel, which is then transferred to the target surface within 3 min. Three monolayers are simultaneously transferred on one substrate with controlled shape and arrangement. The same approach is applied onto nanofiber scaffolds that are cultured for more than 5 d. Every type of monolayer shows proliferation and migration on nanofiber scaffolds, and the formation of robust cell-cell contact is revealed by CD31 staining in endothelial cell layer. A vascular structure with multicellular components is fabricated by transfer of three monolayers on nanofibers that are manually rolled with the diameter and length of the tube being approximately 3 mm and 12 mm, respectively. Collectively, it is concluded that the tissue transfer printing is a useful tool for constructing a vascular structure and mimicking natural structure of different types of tissues.