Particle Bombardment Gene Delivery
Particle bombardment technology, also known as biological biolistics or bioballistics, is a nonviral, physical gene delivery method in which target cells are transfected using DNA-coated particles. Cornell University horticultural scientist John Sanford and cohorts developed the technique in the early 1980s. The technology is a very effective gene delivery method for plant cells, as it can efficiently penetrate cell walls that are hard to pierce with other transfer methods, such as the walls of primary cells. Although still used heavily for plant and agricultural research, particle bombardment gene delivery has also gained popularity for use with a wide array of cell types and organisms, ranging from rodents to humans. Bombardment gene delivery is based on the fact that DNA adheres to certain types of metal particles, such as gold and tungsten. Gold is the preferred particle but due to its cost, tungsten is widely used. The DNA-metal particle hybrids are placed in a chamber and literally fired into a body of cell targets at a high rate of speed using a pressurized gas such as helium. Upon contact, the DNA-coated particles are absorbed by the target cells and identified by gene markers. The use of bombardment gene delivery technology in neuroscience research has soared in the past few years. Several animal studies have suggested that the use of bombardment gene delivery is more successful than other gene delivery methods, including hydrodynamics and ultrasound. However, this technique is not without its limitations. The largest drawback is that tissue and cell damage can occur due to the fast-moving particles. While many academic laboratories build their own systems, commercial systems are available. Bio-Rad Laboratories is the leading vendor of systems and consumables for biolistic gene delivery. Its flagship system, the handheld Helios, is commonly referred to as the “gene gun,” whose exclusive distribution rights Bio-Rad acquired from DuPont. The Helios is designed to transfect in vivo cells and has a pressure range of 100–600 psi. In addition to Helios, Bio-Rad also sells a larger system, the PSD-1000/He. Designed for in vitro applications, the PSD-1000/He has a pressure range of 450–2,200 psi and is often used for adherent cells. Other vendors of bombardment gene delivery systems include Taiwan-based BioWare Technology and Chinese company Ningbo Scientz Biotechnology. Bombardment gene delivery technology is a somewhat novel technique within the $300 million transfection market. The biggest factor hindering the growth of this technology is that many laboratories build their own systems. Current growth is driven by the technique’s ability to transfect most cell types. However, the technology’s true growth potential will be realized when its use for clinical applications, such as gene therapy, is fully realized.