Immune cells in intracerebral hemorrhage

Intracerebral hemorrhage (ICH), the deadliest form of stroke, is characterized by bleeding into brain parenchyma and formation of hematoma. Currently, there is no treatment available for ICH. Inflammatory response is a key pathology of ICH and plays a dual role in ICH---contributing to both secondary brain injury and recovery processes. This review discusses different types (both brain-resident and infiltrated) of immune cells and their functions during inflammation processes following ICH. Specifically, the temporal dynamics, polarization, and function of microglia/macrophages, neutrophils, lymphocytes, and astrocytes in ICH are summarized in a cell-specific manner. In addition, we also discuss key challenges and unanswered questions that need to be addressed in the future. A thorough understanding of the functions of different immune cells in ICH will provide a strong foundation for future studies and lead to the identification of novel cellular/molecular targets for therapeutic development.