Establishment Of Liver And Colon Cancer PDX Models In Immunocompetent Mice Based On Microcarrier 6

BackgroundAnimal model is an important research tool in tumor research.PDX(patient derived xenograft)model is a human tumor xenograft model,which is widely used in current research.PDX model is a kind of animal model constructed by transplanting tumor tissue or cells of patients into mice.Because it can reflect the characteristics of the original tumor,this model is important for tumor research.Human tumor cells in an immunocompetent mouse will be attacked by the mouse immune system and be eliminated so that it is difficult to form a tumor.Therefore,the traditional PDX model uses immunodeficient mice.However,immunodeficient mice can not reflect the changes of immune system in the process of tumor development.Therefore,PDX model can not be applied to the research related to immune system,including drug screening or development which depends on immune system.Drug screening is one of the important applications of PDX model.Microcarrier 6 comes from Shanghai Meifeng Biotechnology Co.,Ltd.It is a multi-layer porous strip like microcarrier,which can cross link and curl with each other to form an irregular structure with enough space.The structure can protect the growing tumor cells from immune cells in a period of time.In addition,Microcarrier 6 has low immunogenicity,biocompatibility and metabolizability.Therefore,it can provide a stable environment for tumor cells in immunocompetent mice,so as to establish PDX models in immunocompetent mice.Previous studies have used Microcarrier 6 to establish gastric cancer model in immunocompetent mouse.However,it used human tumor cell lines to establish cell-derived xenograft(CDX)model.Based on the above,the establishment of PDX model in immunocompetent mice with Microcarrier 6remains to be explored.The immune system has some changes in the process of tumor development.From the surveillance and clearance of tumor cells by immune system to the resistance and escape of tumor cells to immune system,there is a relationship between tumor and immune system.Inspired by the infiltration of T lymphocytes into tumor,immunotherapy such as in vitro expansion and autologous transfusion of immune cells and immune checkpoint inhibitors have been developed.The main phenotype of total T lymphocytes is CD3~+,which includes two subsets:CD4~+T lymphocytes and CD8~+T lymphocytes.The two subsets play a variety of substantial roles in the occurrence and development of tumor.For example,CD4~+T lymphocytes can drive cancer into senescence;CD8~+T lymphocytes can directly infiltrate into tumor tissue and play their cytotoxic role.We can explore the changes of T lymphocytes in the development of tumorigenesis by immunocompetent mice PDX models.ObjectiveTo establish the PDX models of liver and colon cancer in immunocompetent mice by Microcarrier 6,and based on the immunocompetent PDX models of liver cancer,to identify the changes of T lymphocytes,including CD4~+T lymphocytes and CD8~+T lymphocytes subsets,in the process of tumor development.Methods1.Human primary liver cancer cells were isolated and extracted,and then co-incubated with Microcarrier 6.Then it was inoculated into immunocompetent mice to form a co-incubation group.Compared with mice inoculated with human primary liver cancer cells alone and mice inoculated with Microcarrier 6 alone,it was to prove that the establishment of immunocompetent PDX model could be realized,and Microcarrier6 played a key role in it.2.Human primary colon cancer cells were isolated and co-incubated with Microcarrier 6,and then inoculated into immunocompetent mice to form a co-incubation group.Compared with mice inoculated with human primary colon cancer cells alone and mice inoculated with Microcarrier 6 alone,it was to prove that the PDX models of different tumor types(liver cancer and colon cancer)in immunocompetent mice could be established based on Microcarrier 6.3.The PDX model of liver cancer in immunocompetent mice was re-established.Compared with the mice inoculated with Microcarrier 6 alone,the changes of T lymphocytes and the subsets,CD4~+T lymphocytes and CD8~+T lymphocytes,in peripheral blood and spleen of the two groups were analyzed by flow cytometry.Results1.Based on Microcarrier 6,we successfully established immunocompetent liver cancer PDX models.Neither human primary liver cancer cells alone nor Microcarrier6 alone could produce a tumor.2.Based on Microcarrier 6,we successfully established immunocompetent colon cancer PDX models.Neither human primary colon cancer cells alone nor Microcarrier6 alone could produce a tumor.Based on Microcarrier 6,different cancer(liver cancer and colon cancer)PDX models were successfully established.3.The total T lymphocytes in the peripheral blood and spleen were decreased in the experimental group(P<0.01).In the peripheral blood and spleen,CD4~+T lymphocyte subset also decreased in the experimental group with statistical significance(P<0.01).However,CD8~+T lymphocyte subset was slightly increased in the peripheral blood,while it was slightly decreased in the spleen without statistical significance.Conclusion1.Microcarrier 6 can be used to establish immunocompetent liver cancer PDX models,and Microcarrier 6 plays a key role in it.2.Based on Microcarrier 6,we can establish immunocompetent colon cancer PDX models,and Microcarrier 6 plays a substantial role in it.Microcarrier 6 can help to establish immunocompetent different cancer PDX models.3.In the short-term development of liver cancer in immunocompetent mice,T lymphocytes and CD4~+T lymphocyte subsets in peripheral blood and spleen were inhibited;CD8~+T lymphocyte subsets may not be inhibited or promoted in peripheral blood and spleen;the inhibition of total T lymphocytes may be mainly due to the inhibition of CD4~+T lymphocyte subsets.