Figure 2

Damage patterns in MI models and MI wound repair process. (A) Representations of zebrafish MI models and their damage patterns. Genetic ablation targets only myocardium and is resolved in 30 days. Resection models are transmural but remove tissue that would otherwise require cellular debridement and cause extracellular matrix (ECM) protein deposition that is inconsistent with mammalian MI. Resection injury resolves in 60 days. Cryoinjury is a transmural injury model that closely resembles mammalian MI, requiring cellular debridement and showing ECM protein composition and deposition patterns like those observed in mammalian MI. (B) Stages of wound repair in mammalian and zebrafish cryoinjury MI by stage. The inflammatory stage lasts from 0 to 3 days of injury and is characterized by inflammatory cell recruitment and inflammatory responses governed by the innate immune system. The reparative phase lasts 3–14 days in mammals or 3–7 days in zebrafish cryoinjury models. During this stage, ECM deposition provides a scaffolding for wound resolution. Wound resolution ends with characteristic loss of cardiomyocytes, scarring, and decreased cardiac function in mammals, while zebrafish can regenerate lost cardiomyocytes from cryoinjury within 130 days of injury.