Heterogeneity of Brain Metastasis-associated Microglia and Macrophages

Brain metastasis (BrM) represents a challenging clinical issue. The most common treatment options are surgery and irradiation. Little is known about the complex cellular and molecular microenvironment of BrM, thus lacking molecular targets to combat this dismal disease. It is known that macrophages from the periphery (monocyte-derived macrophages, MDM) and microglia, the brain-resident macrophages, comprise the most abundant stromal cell types in BrM. However, it is not known if both cell types represent a homogeneous cell population with redundant functions or if there are differences due to their ontologic origin. Besides breast cancer and melanoma, the highest incidence of BrM can be found in lung cancer. To gain deeper insight into the myeloid immune landscape and the heterogeneity of BrM-associated immune cells, we here provide single cell RNA Seq data of microglia and MDMs which were associated with a lung cancer (LuCa) BrM, as well as with an irradiated LuCa BrM. Cells were FACS purified into 384 well plates, snap frozen on dry ice and single cell RNA-Seq performed. Together, our data hint towards cell type-specific heterogeneity both, before and upon application of irradiation. Single cell RNA-Seq of FACS-purified microglia and macrophages out of lung cancer brain metastasis