Researches On Hyperthermia Using Magnetite Thermoseed Combined With Astragalus Mongholicus To Mediate The Abcopal Antitumor Effect On The Rat Walker-256 Tumor

Objective:We explored the anti-tumor treatment effect of hyperthermia induced by magnetic thermoseeds at different temperatures in Walker-256 tumors to determine the abscopal anti-tumor effect of local heat treatment combined with astragalus mongholicu and the feasibility of this technique to stimulate immune function in tumor-bearing rats.Methods:Walker-256 tumor cells were injected into the abdominal cavity in Wistar rats,to form tumor ascites.The rats in the experimental groups also received a flank subcutaneous inoculation of cells to form two tumors.After induction of the tumors,the rats were randomly assigned to seven groups: control group(group C),thermoseed comparison group(group T),magnetic comparison group(group M),and two groups for hyperthermia(group H1: 42-46℃for 30 min;group H2:50-55℃for 10min),two groups for astragalus combined with hyperthermia(group C1:42-46℃for 30 min,group C2:50-55℃for 10 min),and we also set the normal comparison group(group N).For the four hyperthermia groups,putting the thermoseeds in one side tumor of the hind-leg,leaving the tumor in the center of the alternating magnetic field for hyperthermia,not dealing with the other side tumor.Tumor growth was monitored in all groups every 2 days.Fourteen days after the treatment,tumor tissue was excised from all rats and fixed in 10%formalin for histological assessment of the tumor tissue.We used immunohistochemistry to detect tumor tissue expression of PCNA for each group.Peripheral blood samples were also obtained and flow cytometry was used to determine the populations of CD4+, CD8+and CD4+/CD8+T cells in each group.Serum samples were prepared and levels of INF-γand IL-2 were measured by enzyme-linked immunosorbent assays (ELISA).Results:We found that hyperthermia treatment combined with astragalus mongholicu inhibited tumor growth at the site of heat application.Growth of the tumor on the contralateral side,which was not heated,also showed inhibition of tumor growth.Histological observation showed necrosis of tumor cells on both sides.The expression of PCNA was decreased in the four hyperthermia groups,and the effect was greater in group C2 than in group C1.Flow cytometry revealed that CD4 subsets in astragalus combined hyperthermia groups and hyperthermia groups were higher than those in the three control groups,the CD4/CD8 were significantly higher as compared with those in the three control groups,while CD8 declined in the four experimental groups and all the datas are with statistical difference,(P＜0.05),the effect of the group C2 is much more apparent than the group C1.with significant difference,(P＜0.01).The concentrations of INF-γand IL-2 were significantly higher in the four experimental hyperthermia groups than in the control groups(P＜0.01).Conclusions:Magnetic induction hyperthermia combined with astragalus mongholicu is an effective way to treat tumors.In the present study, application of hyperthermia at 50-55℃for 10min had the most marked anti-tumor effect.Magnetic induction hyperthermia combined with astragalus mongholicu induced abscopal anti-tumor effects and stimulated endogenous immune responses in Walker-256 tumor-bearing rats.