The objective of the present study was to investigate the effects of mesenchymal stem cells (MSCs) genetically modified by lentivirus-mediated mouse interleukin-12 (Lenti-mIL-12) in treating malignant ascites in mice. The in vitro chemotactic effect of Lenti-mIL-12-MSC culture supernatant on dendritic cells was investigated using a chemotaxis chamber. Liver cancer H22 and MethA ascites models were constructed. Mice were divided evenly into four groups: Normal saline, MSC, Null and Lenti-mIL-12-MSC. The survival rate, ascites volume and red blood cell number were measured for these groups. The toxicity and side effects of Lenti-mIL-12-MSCs were investigated using visual and microscopy inspections. The results indicated that mIL-12 had a strong chemotactic effect on dendritic cells. mIL-12 was highly expressed in ascites of Lenti-mIL-12-MSC-treated mice. Lenti-mIL-12-MSCs reduced the volume of ascites and the number of red blood cells in ascites and thus increased the survival rate and prolonged the survival duration of the mice. Furthermore, Lenti-mIL-12-MSCs showed no toxicity and side effects on the mice with malignant ascites. In conclusion, the results demonstrated that Lenti-mIL-12-MSCs inhibited the growth of ascites and promoted the survival of tumor-bearing mice, suggesting that Lenti-mIL-12-MSCs exerts a therapeutic effect on malignant ascites by stimulating the immune responses of the mice.
Keywords: immunotherapy; interleukin-12; malignant ascites; mesenchymal stem cells.