Quantitative relations between acoustic inertial cavitation and gene transfection rate/cell viability

Ultrasound has been utilized to assist gene transfection. In combination with ultrasound, microbubble-based contrast agents have also been used to enhance the transfection efficiency by inducing acoustic inertial cavitation. However, the relations between inertial cavitation and gene transfection rate/cell viability are still unknown. It is the primary purpose of this study to examine the relations experimentally and quantitatively. A commercial contrast agent Levovist (R) was used, and the cavitation was represented by the parameter ICD (inertial cavitation dose). The relations between ICD and gene delivery rate/cell viability were studied under various acoustic pressures, microbubble concentrations and pulse durations. Concentration of cells (HeLa cells) and DNA (short DNA-FITC molecules) were 2 x 10(5) cells/mL and 40 mu g/mL, respectively. Linear regression was performed on the delivery rate versus ICD and the cell viability versus ICD. For the delivery, y = 28.67x + 10.71 (x: ICD, y: delivery rate) was obtained (R-2 = 0.95). On the other hand, y = -62.83x + 91.18 (x: ICD, y: cell viability) was obtained (R-2 = 0.8) for cell viability. The results show high correlations between delivery rate/cell viability and ICD.