Mechanisms and functions of intercellular mitochondria transfer to and from macrophages

Cell-to-cell communication is essential for maintaining homeostasis and coordinating complex biological processes in multicellular organisms. Classically, cells communicate using secreted peptides and metabolites and through cell contact-dependent signaling. Emerging studies over the past 20 years indicate that many cell types, including innate immune cells such as macrophages, participate in a process called intercellular mitochondria transfer, in which macrophages either donate their own mitochondria to other cells or accept mitochondria originating from another cell type. This raises the intriguing possibility that macrophages use mitochondria transfer as a mechanism of cell-to-cell communication. In this review, we describe the distinct mechanisms and functional roles of mitochondria transfer in macrophages across different organ systems and highlight how this biology contributes to health maintenance and disease pathogenesis.