The use of a needle-free injector for DNA vaccination in BALB/c mice

The capability of DNA vaccine to transfect cells determines the success of DNA vaccine, but there are some natural obstacles that reduce the efficiency of DNA delivery into cells. One way to overcome this problem is through the use of a delivery systems such as needle free injectors (NFIT). In the present study, we evaluated 2 kinds of NFITs, Injex and Twin-Jector EZII, and as control we use hypodermic syringes. The path of injection and the capability of NFITs to deliver DNA into cells were observed by using India ink and plasmid coding enhanced green fluorescent protein (pCDNA eGFP) respectively. A mass of 50 µg pcDNA3.1-eGFP in 50 µL of PBS and India ink were injected into the mouse thigh using these three delivery systems. Two days post-injection, histological slides were prepared from the thigh muscle and the expression of eGFP was observed by confocal microscopy. The results show that all the delivery systems used in the present study were able to deliver India ink and pcDNA3.1-eGFP to the thigh muscle. There was a difference in the spread of Indian ink produced 3 kinds of delivery systems used in this study. Furthermore, there was also a difference in the distribution of eGFP expression cells, that corelated with the pattern of the path /spread of fluid produced by the three delivery systems. The number and intensity cell expressing eGFP was intense in mice injecting with hypodermic syring compare to Injex and Twin-Jector EZII. - The results seen with India ink support the eGFP expression results. In conclusion, needle free injection can be used to deliver DNA into BALB/c muscle, but less efficient compared to hypodermic syringe.