In vivo gene delivery is usually achieved by one of two methods: viral vectors or electroporation. Electroporation works by delivering the plasmid DNA to the target area and then applying an electric field around that area triggering the uptake of the DNA by cells. Physical and electrical components significantly affect the efficiency of this process. Therefore, the choice of the best electrode for a specific application is particularly important. Recently our lab has been using the BTX 2-Needle Array, from the BTX Division of GeneTronics, for this purpose. The BTX 2-Needle Array is an electrode specifically designed for muscle
in vivo gene delivery but can also be used for targets as diverse as glioma and testis.
The BTX 2-Needle Array consists of a couple of stainless steel needles connected trough a handle to a power supply. The needles are very thin, 20 mm long and 5 or 10 mm apart from each other. However, the gap can be reduced at will since the needles are flexible. Although designed to be compatible with several BTX generators, their capabilities (voltage range 1-500 V, pulse length range 1 microsec-99 msec) also makes them compatible with a wide variety of electroporation systems. Regardless of the system used, it is worth noting that for in vivo electroporation, a square-wave porator is required. The BTX 2-Needle Array is sold in six-pack, sterile assemblies. Although defined as disposable by the manufacturer, every BTX 2-Needle Array can be used many times without compromising the pulse delivery.
I have used the BTX 2-Needle Array, connected to a BTX ECM 830, to transfect expression vectors for GFP-fusion proteins into adult mouse skeletal muscle. Using this system, I have increased the transfection efficiency by at least 1.5 orders of magnitude in respect to the transfection of regenerating muscle. I especially appreciated the tiny dimensions of the 2 needles when transfecting the Soleus, which is a muscle few mm long and maybe 1-2 mm wide, located deep in the hindlimb. Another positive aspect of the BTX 2-Needle Array is the fact that they are actually reusable. This is very important to cut the costs, which become negligible for the electrodes alone. Overall, these electrodes are well designed, easy to assemble, and practical to use. The only part I would change is the connection cable, which is not very soft and so has the tendency to coil instead of just laying down. When buying BTX 2-Needle Array be advised that it is not necessary to take the additional “high voltage banana cable”, as suggested in the manufacturer’s specifications sheet.
Overall, I have been satisfied with the BTX 2-Needle Array’s performance. It has reproducibly given me high-levels of in vivo gene delivery in skeletal muscle. I would definitely recommend it as one of the best kind of commercially available electrodes for this application.
Dario Coletti, PhD
Post-Doctoral Fellow
Mount Sinai School of Medicine