【Animal Modeling】- Establishment of a mouse model of lung metastasis and postoperative recurrence after bone marrow injection

  Objective To establish a model of lung metastasis and postoperative recurrence by bone marrow injection, to reveal the superiority and feasibility of the model by bone marrow injection, and to provide a new research basis for the study of lung metastasis of malignant tumors.

  Methods Mice were divided into breast pad injection group, subcutaneous injection group, tail vein injection group and bone marrow injection group. Different models were constructed using 4T1 cells to observe the growth, survival and metastasis efficiency of primary tumors in different groups. Different numbers of 4T1 cells were injected to observe the time when lung metastasis occurred. The postoperative recurrence model was established by injecting 4T1-luc cells into the bone marrow. The mice were divided into sham amputation group, amputation group on day 3, amputation group on day 7 and amputation group on day 10. The lung metastasis of mice was observed by in vivo imaging.

  Results Compared with breast pad injection and subcutaneous injection, bone marrow injection had no effect on the growth of primary tumor, but its survival time was significantly shortened. Compared with breast pad injection, subcutaneous injection and tail vein injection, bone marrow injection was the most efficient for lung metastasis. Bone marrow injection only required 1×105 4T1 cells to develop lung metastasis on day 12. Bone marrow-injected model mice can still cause lung metastasis and primary tumor recurrence after amputation.

  Conclusion The mouse model of lung metastasis by bone marrow injection and the mouse model of postoperative recurrence were successfully established. The mouse model using this injection method has the characteristics of short survival time and high metastasis efficiency, and can be used for the mechanism research and drug screening of malignant tumor lung metastasis.