Figure 1.

Wild-caught and laboratory-reared animals employed to characterize the immune response to injury during regeneration and fibrotic repair using a comparative ear punch assay. (A) Immune-primed A. percivali (wild-caught) and M. musculus (privately bred) were acquired in Kenya and housed in an open-air facility in Nairobi. A. cahirinus and M. musculus used at the University of Kentucky were captive bred from lab colonies in a clean facility and considered to have naïve immune systems. We also trapped M. musculus in Kentucky. (B) Schematic depicting excision of a 4 mm circular hole in the ear pinna (D0) and subsequent regeneration and fibrotic repair in Acomys and Mus, respectively. Local inflammation follows tissue excision and persists until ~D10 (red) (16, 42). Keratinocyte activation leads to re-epithelialization between D5 and D10 (yellow box) (41, 43). New tissue formation follows re-epithelialization and is characterized by a strong upregulation of extracellular matrix proteins. Matrix production is biased toward collagen production and fibrosis in Mus, leading to scar formation and an open hole (light blue). In Acomys, robust cell proliferation is maintained until the entire hole is filled with new tissue that undergoes morphogenesis to replace all of the original tissue components (e.g., epidermis, dermis, hair follicles, sebaceous glands, cartilage, etc.) (gray).