Xenograft Tumor Models

        Xenograft model of breast cancer is an important tumor research tool. This model usually involves transplanting human breast cancer tissue or cells into immune deficient mice to make the tumor grow in mice. 

        In this process, tumor tissue from tumor patients is first transplanted into severe immunodeficient mice (NSG) so that the tumor tissue grows in the mice to form a first-generation transplanted tumor. When it grows to a certain size, the transplanted tumor tissue is removed and transplanted into a new batch of mice under aseptic conditions to form the second-generation transplanted tumor. This procedure is repeated to form the third and fourth generation of transplanted tumors. 

        The advantage of this model is that the growth microenvironment of the original tumor is preserved as much as possible, which is conducive to a better representation of the original tumor characteristics and maintains the heterogeneity of the tumor. However, there are some problems with this model, for example, the DNA fragments extracted from this model contain not only human genes, but also a percentage of mouse fragments. Another problem is that the model lacks paired normal samples. 

        Xenograft model of breast cancer has been widely used in both basic and clinical research to simulate the process of human malignant tumor occurrence and development. However, it should be noted that the selection of appropriate cell lines is also very important due to the existence of different molecular typing of human breast cancer and the fact that human breast cancer cell lines are more difficult to become tumors and are unstable compared to other cancer types.