Yuichi Tei

Ultrasound-mediated gene transfection in vitro: Effect of ultrasonic parameters on efficiency and cell viability

Ultrasound (US)-mediated gene transfection in the presence of microbubbles is a recently developed and promising non-viral gene delivery method. Optimising the parameters used in ultrasonic transfection is urgently required in order to realise higher transfection efficiencies in clinical settings. This study examined the effect of ultrasound exposure parameters on plasmid DNA transfection in mouse embryonic fibroblast cell lines using perfluorobutane bubbles. Variations in US intensity (0–11 W/cm2), pulse repetition frequency (PRF, 50–50,000 Hz), duty ratio (10 to 50%), exposure time (0–120 s) and microbubble volume concentration (0 to 10%) were tested, and the microbubble volume concentration was also monitored during exposure. Through the experiments, the mechanism of how variations in parameters influence US-mediated gene transfection was discussed, which can provide a basis for future applications of ultrasound mediated transfection.

An Introduction of New Artificial Bone Unit “Tetra-Bone”

We fabricated a small α-TCP ceramic unit having four pods, named “Tetra-bone” employing a ceramic injection molding. Tetra-bone can keep uniform concave geometry among the pods as well as immobilizing each other. Owing to the monotony of Tetra-bone, weight of Tetrabones used can be converted into the number of Tetra-bones, volume that can be filled with Tetrabones, and the number of functional structures. By using Tetra-bones, bone defects can be filled with intentional geometry that helps to discuss the relation between geometric features of pores and bone formation.

Ultrasound Gene Transfer into Fibroblast Cells using Microbubbles

Ultrasound is widely applied in the medical field and offers the strong advantages of non‐invasiveness and high‐selectivity. Gene transfer using ultrasound, which is called sonoporation, is one application. Ultrasound has the potential to deliver therapeutic materials such as genes, drugs or proteins into cells. Microbubbles are known to be able to improve delivery efficiency. This is attributed to therapeutic materials passing through the cell membrane after permeability is increased by destruction or oscillation of microbubbles. The present study tried to deliver the GFP plasmids into fibroblast cells. Cells were cultured in 6‐well culture plates and exposed to ultrasound (frequency, 2.1 MHz; wave pattern, duty cycle 10%; intensity, 0–26 W/cm2; time, 0–200 s) transmitted through medium containing microbubbles (Levovist® (void fraction, 8×10−5) or Sonazoid® (void fraction, 0–24×10−4)) and GFP plasmids at a concentration of 15 μg/mL. Density of microbubbles after ultrasound irradiation was measured. When ...

Microbubble‐Enhanced Ultrasound Gene Transfer into Fibroblast Cells

Ultrasound finds many applications in the medical field, including ultrasound imaging, non‐invasive treatment of tumors and lithotripsy. Ultrasound also has a potential to deliver some therapeutic materials, such as genes, drugs or proteins into cells. It is known that microbubbles can improve the delivery efficiency. It is believed that therapeutic materials can pass through the cell membrane whose permeability is increased by microbubble destruction or the ultrasound pressure. In this study, we investigated the delivery of GFP plasmid gene into the fibroblast cells. Ultrasound (frequency = 2.1 MHz, duty cycle = 10%) was used to irradiate the cultured cells through a medium that contains microbubbles and GFP plasmid. GFP plasmid transfection could be easily observed by fluorescence microscopy. Ultrasound irradiation under a variety of conditions resulted in successful GFP plasmid delivery. Microbubbles enhanced GFP transfection, and conclusions were drawn as to the relationship between gene transfection ...