A single cell contains a variety of organelles, including a nucleus, mitochondria, the golgi apparatus and others. If it were possible to prepare a nano craft that could specifically target a specific organelle, it would open a new field of research directed toward therapeutic treatments for a variety of diseases. We recently developed a new concept that we refer to as “Programmed Packaging”, by which we succeeded in creating a multifunctional envelope-type nano device (MEND) as a non-viral vector. Our attempts to target mitochondria are discussed here, mainly focusing on a MITO-Porter, a MEND for delivering cargoes to mitochondria. A variety of human diseases, including various neurodegenerative disorders, ischemic heart disease, diabetes and cancer have been reported to be associated with mitochondrial dysfunction. Because of this, mitochondrial therapy would be expected to be useful and productive in the treatment of such diseases. Our findings regarding mitochondrial drug delivery systems that are directed toward mitochondrial nano medicine development are summrized herein.

The effect of extracellular polymeric substance (EPS) of Escherichia coli was investigated through the bacterial adhesive behavior onto the glass surface. The adhesive forces were estimated using the parallel plate flow chamber (PPFC) and the atomic force microscope (AFM). In the case of adhered cells attached for 3 ‍h on a glass substratum, PPFC measurements revealed that the adhesive force for a washed cell (without EPS) was about three times larger than that for an intact cell even though the EPS increases the bacterial adhesive force basically. Interestingly, AFM force measurements also revealed that the EPS reduced the bacterial adhesive force between a cell and a glass bead. These results indicates that the existence of EPS on the bacterial cells increases the separation distance between a cell and a solid surface, leading to the inhibition of the initial bacterial adhesion.

Particles of additives that are ingested along with food can either adhere to the intestinal microflora or be absorbed, and these may possibly lead to illnesses caused by changes in the microflora composition. Barely 1% of Fe₂O₃ particles dissolve in acids present in the stomach. In addition, the direct administration of Fe₂O₃ particles into the stomach with a probe showed no adverse health effects. However, mixing Fe₂O₃ particles of a smaller diameter into food and orally administering the dose over a period of more than 2 weeks encouraged the multiplication of the diarrhea-causing Clostridium family amongst intestinal flora, indicating the cause of the diarrhea outbreak. On the other hand, multiplication of the Clostridium species was suppressed by the multiplication of another family within the intestinal flora, namely Lactobacillus. It was confirmed that by analyzing the formation of fermentation products such as hydrogen, acetic acid, and lactic acid, symptoms of diarrhea caused by the alteration of intestinal microflora composition spontaneously recovered.

Centrifugal spinning process with duplex tube nozzle for the fabrication of core-shell structured edible fiber was successfully developed. Using maltose enabled fibers to be relatively stable against humidity of air. Fat-soluble materials could be successfully encapsulated by the employment of domain-matrix structure where maltose aqueous solution is continuous phase and oil is dispersed phase. In order to protect encapsulated material from oxidation or leakage, core-shell structured fiber, where domain-matrix structure fibers were enwrapped by maltose shell, was developed. The required condition to obtain core-shell structure was considered based on Hagen-Poiseuille equation, and the ratio of cross section averaged linear velocities of 0.97 was accomplished.

Fluorescent microscopy confirmed the core-shell structure and SEM observation revealed that domain-matrix structure fibers without shell had rough surface probably due to the detachment of domain oil phase, by contrast core-shell structured fibers had quite smooth surface. This may be attributed to the protection from detachment of oil phase by shell material, which was supported by the result of pyrene elution experiment.

Human dental pulp cells are a valuable source for the generation of patient-specific induced pluripotent stem cells (hiPSCs). We previously generated hiPSCs from deciduous dental pulp cells using three factors, Oct3/4, Sox2, and Klf4 and evaluated the feasibility of hiPSCs as substrates for tooth-forming cells.

Third molar tooth buds were extracted from the mandibles of 6-month-old pigs. After removal of the calcified tissues, the heterogeneous cells were isolated from third molar tooth and then were mixed with hiPSCs. The mixed cells were seeded in poly (D, L-lactoc-coglycolic acid) (PLGA) scaffolds and then were transplanted into the omentum of the immunocompromised rats. The implants were harvested at 16 weeks after transplantation. Histologically, a number of small pieces of tooth-like tissues were observed in the implants. Enamel structure, dentin-predentin complex, and cementum structure were present histologically and the specific cells were stained positive for both human mitochondria and specific antibodies. The results suggested that hiPSCs have a potential to differentiate into ameloblasts, odontoblasts, and cementoblasts.