Magnetic stent hyperthermia for esophageal cancer: An in vitro investigation in the ECA-109 cell line

Magnetic stent hyperthermia (MSH) is a novel approach for targeted thermotherapy for esophageal cancer, which is based on the mechanism that inductive heat can be generated by the esophageal stent upon exposure under an alternative magnetic field (AMF). A positive effect of MSH on esophageal cancer has been demonstrated, however, there is no study on the in vitro effects of heating treatment or of the effects of AMF exposure on human esophageal cancer cells. This study aimed to investigate the effect of MSH and of AMF exposure in esophageal cancer cells. Inductive heating characteristics of esophageal stents were assessed by exposing the stents under AMF. A rather rapid temperature rise of the Ni-Ti stent when subjected to AMF exposure was observed and the desired hyperthermic temperature could be controlled by adjusting the field parameter of the AMF. Human esophageal squamous carcinoma (ESCC) ECA-109 cells were divided into four groups: the control group, the water-bath heating group, the MSH group and the AMF exposure group. Hyperthermic temperatures were 43, 48 and 53˚C and the treatment time was in the range of 5-30 min. The MTT assay, apoptotic analysis and TUNEL staining were applied in the current investigation. Exposure of ECA-109 cells under AMF with a field intensity of 50 to 110 kA/m had negligible effect on cell viability, cell necrosis and apoptosis. Hyperthermia had a remarkable inhibitory effect on the cell viability and the effect was dependent on the thermal dose (temperature and time). The optimal thermal dose of MSH for ECA-109 cells was 48˚C for 20-30 min. The study also elucidated that there was a difference in the effects on cell necrosis and apoptosis between the heating mode of water bath and MSH. The data suggest that MSH may have clinical significance for esophageal cancer treatment.