Local drug and gene delivery through microbubbles and ultrasound.

Although gene therapy has great potential as a treatment for diseases, clinical trials are slowed down by the development of a safe and efficient gene delivery system. In this review, we will give an overview of the viral and nonviral vehicles used for drug and gene delivery, and the different nonviral delivery techniques, thereby focusing on delivery through ultrasound contrast agents. The development of ultrasound contrast agents containing encapsulated microbubbles has increased the possibilities not only for diagnostic imaging, but for therapy as well. Microbubbles have been shown to be able to carry drugs and genes, and destruction of the bubbles by ultrasound will result in local release of their contents. Furthermore, ligands can be attached so that they can be targeted to a specific target tissue. The recent advances of microbubbles as vehicles for delivery of drugs and genes will be highlighted.