ABSTRACT
Objective:To investigate the therapeutic effect of exosomes divided from bone marrow mesenchymal stem cell (BMSC) on pancreatic cancer in vivo through regulation of tumor-associated macrophages (TAM) polarization.Methods:Ten male C57BL/6 mice weighing approximately 20 g, ages 4 weeks, were used for BMSC exosomes extraction and PKH26 labelling. Thirty female SPF BALB/c-nu/nu nude mice weighing approximately (18.56±0.85) g, ages 4-6 weeks, were adopted for pancreatic carcinoma models. The models were randomly divided into 3 groups with 10 in each: control group (injected with PBS through tail vein), portal vein treatment group (injected with exosomes in PBS through portal vein), tail vein treatment group (injected with exosomes in PBS through tail vein). After the models were executive 8 weeks later, the percentage of PKH26 positive-exosomes in pancreas tissue was quantified by flow cytometry technique. The volume of the primary pancreatic tumor, the tumor volume of inhibitory rate, the number of metastatic nodule, and the ascitic fluid were assess. Also, the weight of liver and the tumor weight were evaluated. The expression of M1 and M2 macrophage-activate biomarkers and the content of pancreatic cancer marker B7-H4 tumor carbohydrate antigen 199 in peripheral blood was detected. Moreover, the expression of Survivin and matrix metalloproteinase-9 (MMP-9) in pancreatic cancer tissue cells was also detected.Results:There was no significant difference for the tumor volume of inhibitory rate between portal vein treatment group (72.4±21.6)% and tail vein treatment group (70.1±20.7)% ( t=0.24, P=0.811). Compared with control group, the volume of the primary pancreatic tumor, the weight of liver, the tumor weight, the number and rate of liver metastatic nodule, the ascitic fluid, and the number of other metastatic nodule were totally lower in the 2 treatment groups with significant difference (all P<0.05). Compared with the control group, iNOS and CD68 in portal vein treatment group and tail vein treatment group were increased, while Arginase, CD206, B7-H4, tumor carbohydrate antigen 199, Survivin and matrix metalloprotein-9 were decreased, with statistically significant differences (all P<0.05). Conclusion:Exosomes derived from BMSC can inhibit the polarization of TAM to the M2 phenotype and induce their polarization to the M1 phenotype, thereby suppressing the proliferation, invasion and migration of pancreatic cancer.