Effects of hyperthermia with dextran magnetic fluid on the growth of grafted H22 tumor in mice

Objective: To study the effect of dextran magnetic fluid hyperthermia on growth, vascular endothelial growth factor (VEGF) expression and apoptosis of the grafted H22 tumors in mice. Methods: Mice with grafted H22 tumor were randomly divided into four groups. The treatment group was intratumorally injected with dextran magnetic fluid and subsequently exposed to a 55 kHz 20 kA/m alternating magnetic field for 10 min. The three control groups were respectively injected with physiological saline and no magnetic field; with physiological saline and exposed to 55 kHz 20 kA/m alternating magnetic field for 10 min; and with dextran magnetic fluid only. The inhibitive ratios were calculated. Other mice with grafted tumor were randomly divided into two groups, respectively injected with dextran magnetic fluid or physiological saline and exposed to a 55 kHz 20 kA/m alternating magnetic field for 10 min. The VEGF expression and apoptosis in tumor tissues were analyzed at 1 h, 5 h, 24 h, 48 h and 336 h after treatment. Results: The inhibitive ratio of treated group was 59.74%, 52.51% and 40.35% respectively. Necrotic areas in tumor tissue were mainly distributing around the magnetic fluid and became larger with the lengthening of treatment. The VEGF expression and apoptosis of the treated group did not show obvious difference from that of the control group at different time points. Conclusion: Single time magnetic fluid hyperthermia significantly inhibited growth of grafted H22 tumor in mice, which mainly resulted from inducing necrosis while not inhibiting VEGF expression or inducing apoptosis.