| Co-Investigator(Kenkyū-buntansha) |
TACHIBANA Katsuro Fukuoka Univ., School of Medicine, Professor, 医学部, 教授 (40271605)
IRIE Yutaka Fukuoka University, School of Medicine, Senior Researcher, 医学部, 助手 (80352235)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2004: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
We have previously shown that low intensity ultrasound can induce apoptosis of suspension cells in vitro, and that such apoptosis can be optimized when using pulsed ultrasound. In the present study, we used an ultrasound set up that simulates in vivo condition. The ultrasound device used is variable in terms of intensity, frequency with or without sweeping, pulse repetition frequency (PRF), duty factor (DF), and duration. The set up embeds the sample between 2 cm thick material of soft tissue density and using ultrasound-absorbing rubber on the other side to avoid formation of standing waves. The result showed that the ideal ultrasound conditions to induce apoptosis involve the following parameters: PRF, 0.5 Hz ; DF, 25%; frequency, 1.011 swept at +12% or +12% ; intensities, 0.5 W/cm2 or above; and for 20 sec sonication. However, because necrosis and lysis tend to predominate at higher intensities, optimal apoptosis with minimal instant cell lysis and necrosis could be observed at intensities 0.5-1.2. At optimal condition, 16.5% of cells became apoptotic and 5.9% necrotic as determined by Annexin V-FITC staining and based on PI staining, respectively. Since most of the necrotic cells showed positive also for Annexin V-FITC staining, we could classify most of these cells as in secondary necrosis (cells which initially underwent apoptosis but eventually became necrosis). This findings confirms the ability of ultrasound to induce apoptosis and that this can be optimized even in a condition similar to an in vivo environment, thus suggesting the potential use in therapy.
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