Various methods are used to construct the scaffolds used for bone regeneration. We built a three-dimensional (3D) porous scaffold from layers of pure titanium powder melted with a powerful electron beam. We then added bone morphogenic protein to this scaffold and examined its ability to induce new bone. The surface of the scaffold was rough and the pore size was approximately 1000 μm. Three weeks after implantation, little new bone was observed inside the scaffold, whereas much bone formation had been induced around the scaffold. This study showed that a complex 3D porous scaffold can be fabricated using the electron beam melting method, suggesting that this method is effective for the construction of optimal shapes for new bone induction.
Multi-directional forging (MDF) method is one of the useful techniques for improving the mechanical properties of metals and alloys. In the present study, we aimed to evaluate the cortical bone response of MDF titanium implant by the implantation experiments into the rabbit tibiae. Multi-directionally forged titanium (MDF-Ti) cylinder implants and commercial pure titanium cylinder implants (Ti) with 3.5 mm in diameter and 7.0 mm in height were used. Half of Ti and MDF-Ti were sandblasted. These implants were implanted into bone defects of rabbit tibiae. After 12 weeks postsurgery, the implants were excised and nondecalcified thin sections were prepared. Fluorochrome green labeling by the administration of calcein was clearly observed around both implants at 11 weeks after implantation. No significant difference was observed in length of fluorescence labeling between Ti-Sandblast and MDF-Ti-Sandblast implants (p>0.05). After 12 weeks of implantation, new bone formation was observed around four different implants. There were no significant differences in bone-to-implant contact ratio (BIC) and bone mass (BM) between Ti-As and MDF-As (p>0.05). BICs between Ti-Sandblast and MDF-Ti-Sandblast were not also significantly different (p>0.05). BICs were not significantly increased by sandblasting (p>0.05), but BMs were increased by sandblasting (p<0.05). In conclusion, it revealed that MDF-Ti showed a cortical bone response same as conventional commercial titanium. MDF-Ti will be a candidate for dental implant material instead of titanium alloys.
In the field of regenerative medicine, tissues and organs differentiated from iPS cells are implanted into the body. For this purpose, scaffolds using collagen derived from fish, evolutionarily distant from humans, are safer than those using mammalian (porcine) collagen. In the present study, the differentiation of mouse-derived ES cells was examined using string-like porous collagen derived from tilapia that inhabits tropical and subtropical regions. Cell differentiation into bone or cartilage requires 30-day culture. Whether or not the string-like collagen could withstand the long-term culture was examined, demonstrating that 86% of the collagen retained a gel form during the culture without any effect on ES cell differentiation.
Tissue regeneration is the important issue in the field of operative dentistry. In the previous study, we demonstrated that TNFα activates the potential for totipotency in human bone marrow mesenchymal stem cells (hMSCs) and leads to the regeneration of target cells or tissues along with the appropriate differentiating factor such as Emd-Gel. In this study, we apply the transcription factor set of TNF-α and Amelogenin to the human adipose-derived stem cells (hASCs) and our results indicate that this transcription factor set differentiate hASCs into odontblasts simillary and suggest that TNFα activates potential totipotency of hASCs and the activation can lead to the regeneration of target cells or tissues
We examined the embryotoxicity of dental materials using a three-dimension protocol using porcine collagen gel. Although cell differentiation was hardly observed in dental amalgam, the cell survival ratio of 3T3 cells was the highest level. Glass ionomer cement showed the highest differentiation ratio and there was a tendency that the cell survival ratio of 3T3 cells was the lowest. In the two types of light-cured composite resin showed a moderate embryotoxicity. In this test protocol, it became possible to expose dental materials after curing to the ES cells without using solvents thanks to the application of a three-dimensional culture method using collagen gel. Although this modified EST method has not been subjected to validation test, it can be positively assessed to some extent for in vitro examination of the embryotoxicity level of dental materials.