Enhancing cell kill in vitro from hyperthermia through pre-sensitizing with ultrasound-stimulated microbubbles.

Ultrasound-stimulated microbubbles (MBs) were demonstrated to enhance cell kill from hyperthermia. Definity MBs were injected into wells containing 4T1 cells in culture media and scanned with 1-MHz ultrasound, an exposure duration of 30 s and a negative pressure of 0.5 or 1.3 MPa. Some cell samples were placed in a water bath heated to 42 °C for 5 min. Cell death was quantified. When combining MBs, ultrasound at 1.3 MPa and hyperthermia, more than 58.8% ± 7.21% of cells were nonviable. When exposed to hyperthermia alone or exposure to MBs and ultrasound but no hyperthermia, cell death was less than 10.1% ± 6.96% and 30.1% ± 10.8%, respectively.