Li, L., Yan, B., Shi, Y.Q., Zhang, W.Q., and Wen, Z.L. (2012) Live imaging reveals differing roles of macrophages and neutrophils during Zebrafish tail fin regeneration. The Journal of biological chemistry. 287(30):25353-25360.
Macrophages and neutrophils are the pivotal immune phagocytes that enter the wound after tissue injury to remove the cell
debris and invaded microorganisms, which presumably facilitate the regrowth of injured tissues. Taking advantage of the regeneration
abilities of zebrafish and the newly generated myeloid-specific zebrafish lines with labeling of both myeloid lineages, we
assessed the behaviors and functions of neutrophils and macrophages during tail fin regeneration. Live imaging showed that
within 6 hours post amputation (hpa) - the inflammatory stage, neutrophils were the primary cells scavenging apoptotic bodies
and small cell debris, although they had limited phagocytic capacity and quickly underwent apoptosis. From 6 hpa on - the
resolution and regeneration stage, macrophages became the dominant scavengers, efficiently resolving inflammation and facilitating
tissue remodeling and regrowth. Ablation of macrophages but not neutrophils severely impaired the inflammatory resolution
and tissue regeneration, resulting in the formation of large vacuolesin the regenerated fins. In contrast, removal of neutrophils
slightly accelerates the regrowth of injured fin. Our study documents the differing behaviors and functions of macrophages
and neutrophils during tissue regeneration.