Abstract:

Objective To explore whether ultrasound-mediated microbubble destruction can enhance the expression efficiency of plasmid pIRES -rhBMP2 -EGFP for bone morphogenetic protein -2（BMP -2） in mice skeletal muscle. Methods Twenty four male BALB/c mice were divided into four groups. The naked plasmid was injected into the pretibial muscle or the quadriceps muscle（group A and group C） without ultrasound-mediated microbubble destruction method. Micobubbles with plasmid were injected into the pretibial muscle or the quadriceps muscle（group B and group D） with destructing microbubbles by ultrasound immediately. Twelve mice（group A and group B, 30 μg plasmid  injected） were killed after 7 days and the tissue samples of the pretibial muscle were obtained to observe the expression of enhanced green fluorescence protein（EGFP） by inverted fluorescence microscope, gene transfection efficiencies were quantified by counting EGFP positive fibers on mice skeletal muscle. After 14 days, the other twelve mice（group C and group D, 100 μg plasmid injected） were killed and immunnohistochemical technique was applied to detect the rhBMP-2 gene expression. Results The percentage of GFP-positive fibers was significantly lower in the group A than that in the group B. After 14 days, expression of rhBMP-2 was detected in cells and interstitial spaces in the group C and group D, and expression efficiency of rhBMP-2 in the group D was significantly higher than that in the group C. Conclusion Ultrasound-mediated microbubble destruction could enhance the transfection and expression efficiency of rhBMP-2 gene in skeletal muscle of mouse in vivo. It is a new gene therapy method for periodontal regeneration.

Key words: ultrasound, microbubble, gene therapy, human bone morphogenetic protein-2