[Subcutaneous transplantation of microencapsulated Chinese hamster ovary (CHO) cells/pcDNA 3.1/mIL-12 and subcutaneous transplantation of microencapsulated CHO/pcDNA3.1/mIL-12 combined with 5-fluoro-uracil in treatment of tumor-burdened mice].

OBJECTIVE

To investigate the effect of subcutaneous transplantation of microencapsulated Chinese hamster ovary cells (CHO)/pcDNA3.1/mIL-12 and subcutaneous transplantation of microencapsulated CHO/pcDNA3.1/mIL-12 combined with 5-fluoro-uracilum (5-FU) in treatment of tumor-burdened mice.

METHODS

CHO/pcDNA3.1/mIL-12 and CHO/pcDNA3.1 were suspended in solution of sodium alginate and made into microcapsules. Sixty mice were divided into 6 groups of 10 mice: (1) IL-12 group, microencapsulated CHO/pcDNA3.1/mIL-12 was injected subcutaneously, (2) combined treatment group: CHO/pcDN with 5-FU, (3) 5-FU group: 5-FU was injected intraperitoneally, (4) blank vector group: CHO/pcDNA3.1 was injected subcutaneously, (5) tumor-burdened group: without any treatment, and (6) blank control group: normal mice without any treatment. Except the mice of the blank control group, all mice were injected subcutaneously into the inner side of right thigh with mice colonic adenoma cells. The volume of tumor was measured every third day. 20 days after the treatment, 5 mice in each group were killed to examine the serum Th1 type cytokines: interferon (IFN)-gamma, IL-12, and Th2 type cytokins: IL-4, IL-10 by double antibody sandwich ELISA. The spleens were made into suspension of lymphocytes to examine the activity of natural killer cell (NK) and cytolytic T lymphocyte (CTL). The survival period of the remaining 5 mice in each group was observed till the 60th day.

RESULTS

The activity of NK and CTL were significantly much more in the IL-12 group than in other groups. The activity of NK was significantly much more in combined treatment group than in the tumor-burdened group. The levels of Th1 type cytokines were the lowest in the tumor-burdened group. There was no difference in the levels of Th1 type cytokine between the tumor-burdened group and 5-FU group. However, the levels of Th1 type cytokine were significantly higher in the IL-12 group than in other groups. The levels of Th2 type cytokines were rather high in the tumor-burdened group. There was no difference in the levels of Th2 type cytokine between the tumor-burdened group and 5-FU group. However, the levels of Th2 type cytokine were the lowest in the IL-12 group than in other groups. There was no significant difference in volume of tumor among the tumor-burdened group, blank vector group, and 5-FU group. The mean diameters of tumor in the IL-12 group and combined treatment group were significantly smaller than in the 5-FU, tumor-burdened, and blank vector groups (P < 0.05), however, without a difference between the IL-12 group and combined treatment group. The survival periods of the IL-12 group and combined treatment group were significantly longer than those in the blank vector, tumor-burdened and 5-FU groups (P < 0.05).

CONCLUSION

Microencapsulated CHO/pcDNA3.1/mIL-12 transplanted subcutaneously significantly improves the immune function of tumor-burdened mice and partially overcomes immune suppression caused by chemotherapy, and is effective in slowing the growth of tumor and lengthening the survival period of tumor-burdened ice.