| 이상철, 권현철, 박승우, 김준수, 전은석, 김덕경, 이상훈, 홍경표, 박정의, 서정돈 |
Background: Intramuscular gene injection is a safe method of gene delivery in various muscular or peripheral vascular diseases. We investigated the value of microbubble destruction by low-frequency ultrasound in enhancing gene delivery to skeletal muscles in laboratory animals.
Method: In 68 young mice, 10 mg of luciferase gene was directly injected into the anterior tibialis muscle in an injection mixture of 50ml. The mice were divided into two groups, in which the first group (N=34) the injection mixture was composed of PESDA (perfluorocarbon-exposed sonicated dextrose albumin), and in the second group the solute was the same amount of saline. The groups were subdivided into two groups, with one group receiving 10 seconds of low-frequency ultrasound(20KHz) on the injection site with a sonicator probe directly after injection, and the other without any further intervention. Luciferase activity was measured and compared between each group.
Results: Luciferase activity in each groups were as follows: Luciferase only group (Group 1, N=17), 5727 ± 2178 RLU; luciferase plus ultrasound group (Group 2, N=17), 16480 ± 5239 RLU; luciferase plus PESDA group (Group 3, N=17), 1170 ± 470.7 RLU; luciferase plus PESDA plus ultrasound group (Group 4, N=17), 49910 ± 16500 RLU. The activity was significantly higher in group 4 compared to group 1(p<0.01), showing a 9-fold increase in efficacy of gene delivery by microbubble destruction. The activity was also significantly higher in group 2 compared to group 1(p<0.01), proving that ultrasound itself can increase efficacy of gene delivery. However, the difference in activity between group 2 and group 4 was also significant (p<0.05), showing a 3-fold increase in efficacy with microbubble destruction compared with ultrasound alone. No significant difference was found between group 1 and group 3. No significant damage was found on microscopic examination of muscles after ultrasound exposure.
Conclusion: Microbubble destruction with low-frequency ultrasound is a safe and efficient method of increasing direct gene delivery efficacy to skeletal muscles.
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