Neutrophils are important for the development of pro-reparative macrophages after irreversible electroporation of the liver in mice

Irreversible electroporation (IRE) is a non-thermal tissue ablative technology that has emerging applications in surgical oncology and regenerative surgery. To advance its therapeutic usefulness, it is important to understand the mechanisms through which IRE induces cell death and the role of the innate immune system in mediating subsequent regenerative repair. Through intravital imaging of the liver in mice, we show that IRE produces distinctive tissue injury features, including delayed yet robust recruitment of neutrophils, consistent with programmed necrosis. IRE treatment converts the monocyte/macrophage balance from pro-inflammatory to pro-reparative populations, and depletion of neutrophils inhibits this conversion. Reduced generation of pro-reparative Ly6C(lo)F4/80(hi) macrophages correlates with lower numbers of SOX9(+) hepatic progenitor cells in areas of macrophage clusters within the IRE injury zone. Our findings suggest that neutrophils play an important role in promoting the development of pro-reparative Ly6C(lo) monocytes/macrophages at the site of IRE injury, thus establishing conditions of regenerative repair.