Protocol for generating brain metastatic tumor cells through repeated intracardiac injections in mice.

Here, we present a protocol for generating the lung cancer cell line, LLC1-BMT5, with highly brain metastatic tropism through multiple rounds of in vivo selection. We describe steps for establishing the brain metastases (BrMs) mouse model through intracardiac injection of cancer cells. We then detail procedures for obtaining brain metastatic subpopulations, in vivo selection of LLC1-BMT5 cells, and validating metastatic potential. This protocol will facilitate the study of the molecular mechanisms of BrMs and the development of anti-BrM treatment strategies. For complete details on the use and execution of this protocol, please refer to Wang et al.¹.