Ultrasound-mediated gene transfection: problems to be solved and future possibilities

Together, the human genome project and advances in molecular biology have led to identification of many genes, some useful in the field of medicine. Gene therapy has opened a potentially new therapeutic avenue for managing an array of complicated diseases. One of the more critical areas of gene therapy is the design of an appropriate, accurate, and effective gene transfer system that can be safely applied in vivo. Because no known system meets all the requirements for clinical use, a better, more versatile method of gene transfer is desired. Ultrasound-mediated transfection (USMT) could serve as a potential site-specific gene transfer modality. Although no actual mechanism has yet been thoroughly described, we focus on the principles of USMT, discuss the use of microbubbles as a gene-transfer mechanism, and summarize preliminary in vivo experiments using microbubbles as vectors. Although the published data suggest the promise of this method, extensive improvement in USMT remains essential. Reassuringly, recent success in USMT research has positioned ultrasound as a highly safe modality for gene transfer.