Influence of Ultrasound and Magnetic Field Treatment Time on Carcinoma Cell Inhibition with Drug Carriers: An in...

The influence of exposing carcinoma cells to a static magnetic field (SMF) and low-intensity pulsed ultrasound (LIPUS), for different durations (15-45 min/d), in the presence of magnetic and non-magnetic drug carriers, on their in vitro inhibition is examined. Increasing the exposure time by 15 min/d decreased the culture duration by 24 h to achieve the same level of inhibition in colon (HCT116) and hepatocellular (HepG2) cells. Cell cycle analysis revealed enhanced cellular blockage in G1 and S phases with SMF + LIPUS exposure, and exposure for 45 min/d completely suppressed the S → G2 transition. Apoptosis of both types of cells increased with SMF + LIPUS treatment time, and HepG2 cells exhibited elevated necrosis with >30 min/d exposure. HepG2 cells also had higher amounts of reactive oxygen species (seven- to eightfold) than HCT116 cells (two- to sixfold), suggesting treatment effectiveness is cell and drug carrier dependent. The accelerated cellular activities are attributed to the enhanced internalization of drug carriers as a consequence of destabilized cellular membranes caused by the SMF + LIPUS-generated mechanical and electrical stimuli.