Establishment And Characteristics Of Human Primary Colon Cancer Transplant Tumor Model In C57BL/6 Mice And NSG Mice

Objective:Two types of human primary colon cancer transplantation models of normal immune C57BL/6 mice and immunodeficient NSG mice were established with the help of microcarrier 6 to explore the characteristics and significance of the two models,so as to provide a more suitable model for the study of human colon cancer pathogenesis and the development of new anti-colon cancer drugs.Methods:20 males of C57BL/6 and 20 males of NSG mice 6 to 8weeks of age and 22 to 25 g of body weight were randomly selected as experimental subjects.20 C57BL/6 and 20 NSG mice were randomly divided into two groups of 10 mice each.After the two types of mice were grouped,both one group was inoculated with human primary colon cancer cells by subcutaneous injection(the control group,each mice in the control group was inoculated with 2×10~6 tumor cells PBS 100 ul),and another group was inoculated with human primary colon cancer cell-microcarrier complex(the experimental group,each mice in the experimental group was inoculated with 100uL suspension of 2×10~6tumor cells and 20 ug microcarrier).First,human primary colon cancer cells were isolated and extracted from the surgically excised specimens.Human primary colon cancer cells and microcarrier 6 were co-cultured and prepared with a certain concentration.After subcutaneous transplantation,Changes in appetite,activity and body mass of mice in each group were observed daily,and tumor formation time,tumor size and tumor formation rate were recorded.Tumor-bearing mice were killed at 21 days of inoculation,and the volume,texture,invasion,and degree of necrosis of the tumor were recorded by routine dissection.The pathological tissue of the transplanted tumor was examined by conventional HE staining and immunohistochemical staining.Results:1.The establishment of the cell-microcarrier complex:human primary colon cancer cells isolated and extracted under a microscope were observed as single spherical cells with good refraction;microcarriers were observed under a microscope with a loose texture and irregularities in a large number of pores;The complex was observed under the microscope after 24 hours of co-culture,and a large number of cells were closely attached to the inside and outside of the microcarrier scaffold,showing a saturated state,and densely packed spherical cell clusters were seen on the periphery.2.General conditions and transplant tumor growth of C57BL/6mice:No mice died in the experimental group and the control group.In the experimental group,the body weight increased on the 7th day,and on the 12th day,the body weight increased significantly,and the appetite and activity decreased.The mice in the control group had no significant difference in appetite,activity,and body weight throughout the experimental process.The tumor formation rate of mice in the experimental group reached 80%.On the 7th to 9th days,tumors can be touched on the back.On the 12th to 17th days,subcutaneous bumps on the back are visible.At 3 weeks,the volume of the tumor is about0.6-1.0cm3;The mice in the control group had no tumor formation during the whole experiment.3.General condition and transplant tumor growth of NSG mice:one mice died in the experimental group;no mice died in the cell control group.The mice in the experimental group and the control group showed that the body weight increased on the 5th day,and on the 10th day,the body weight increased significantly,and the appetite and activity decreased.One mice in the experimental group died without tumor formation,and the tumor formation rate reached 90%;The tumor formation rate of the control group NSG mice reached 80%.The experimental group and the control group both were in 5-7 days,and tumors could be touched on the back.A lumpy subcutaneous bulge was visible at 10-15 days.At 3 weeks,the volume of the lumps was about0.8-1.2cm3.4.The histopathological manifestations of transplanted tumors in C57BL/6 and NSG mice are as follows:the envelope of the transplanted tumor is intact,easily separated from the surrounding tissues,diverse in shape,mainly oval,and neovascular network is seen on the surface.Under the light microscope,a large number of deeply stained heterogeneous cells were arranged in disorder,chromatin was coarsely granular,nucleoli was obvious,mitotic figures increased,and infiltration and growth of surrounding tissues,neovascularization was seen at the tumor edge,and occasional necrosis was seen in the center.In the experimental group,a small amount of residual microcarriers were occasionally uncleared.Immunohistochemical staining showed positive expression of CDX-2,CEA,and CK20,confirming that the heterotypic cells were human colon cancer cells.Conclusions:In this study,human primary colon cancer cells were successfullyisolated and extracted from the samples,and the cell-microcarrier complex was established.When the cell-microcarrier complex was inoculated under the skin of the back of C57BL/6 and NSG mice,tumor formation was achieved in both mice,respectively,with tumor formation rates of 80%and 90%.The HE staining and immunohistochemical staining of the transplanted tumor tissues formed by the two mice confirmed that the transplanted tumors were human tumors.Comparing of the tumor formation characteristics of C57BL/6 and NSG mice.The tumor formation time of NSG mice was short and the tumor formation rate was relatively high.The C57BL/6 transplanted tumor model makes up for the deficiency of immune function and provides a more ideal animal model for the study of the relationship between tumorigenesis mechanism and immune function.