Cauterization as a Simple Method for Regeneration Studies in the Zebrafish Heart

Abstract

In the last two decades, the zebrafish has emerged as an important model species for heart regeneration studies. Various approaches to model loss of cardiac myocytes and myocardial infarction in the zebrafish have been devised, and have included resection, genetic ablation, and cryoinjury. However, to date, the response of the zebrafish ventricle to cautery injury has not been reported. Here, we describe a simple and reproducible method using cautery injury via a modified nichrome inoculating needle as a probe to model myocardial infarction in the zebrafish ventricle. Using light and electron microscopy, we show that cardiac cautery injury is attended by significant inflammatory cell infiltration, accumulation of collagen in the injured area, and the reconstitution of the ventricular myocardium. Additionally, we document the ablation of cardiac nerve fibers, and report that the re-innervation of the injured zebrafish ventricle is protracted, compared to other repair processes that accompany the regeneration of the cauterized ventricle. Taken together, our study demonstrates that cautery injury is a simple and effective means for generating necrotic tissue and eliciting a remodeling and regenerative response in the zebrafish heart. This approach may serve as an important tool in the methods toolbox for regeneration studies in the zebrafish.

Comparative Study in Zebrafish and Medaka Unravels the Mechanisms of Tissue Regeneration

“…The cauterization technique involves burning or freezing the target tissue with electric or metal probes and introducing necrotic and apoptotic cell death. Cryoinjury is popular in heart regeneration studies in both zebrafish (Gonzalez-Rosa et al, 2011;Schnabel et al, 2011;Dyck et al, 2020) and medaka (Lai et al, 2017) as it mimics the myocardial infarction in mammals better than resection model (Chablais et al, 2011;Darehzereshki et al, 2015). This technique can also be applied to external organs, such as the fin (Chassot et al, 2016) and gills (Ramel et al, 2021).…”

Unlocking the Secrets of the Regenerating Fish Heart: Comparing Regenerative Models to Shed Light on Successful Regeneration

“…Furthermore, no studies have sought to determine whether the mechanisms that trigger the scarring response (instead of successful regeneration) are shared amongst non-regenerative fish species or whether there are multiple ways in which regeneration can fail. The giant zebrafish (D. aequipinnatus) [81], zebrafish (D. rerio) [8], goldfish (C. auratus) [82], killifish (N. furzeri) [62]and the eyed surface-morph of the A. mexicanus [83] have all been documented to regenerate their hearts after a variety of insults such as cauterisation [84], ventricular amputation, genetic ablation [85] and cryoinjury [86]. However, despite the close relation of the zebrafish to the giant zebrafish and the goldfish, only the killifish and the zebrafish have so far been compared for shared mechanisms of regeneration [62].…”

“…The medaka (O. latipes) [18] and the eyeless cave-dwelling morph of Astyanax mexicanus [83] are the only teleost fish that form a permanent fibrotic scar following cardiac injury (although a scarring response has also been observed in the grass carp: biorXiv https://doi.org/10.1101/627752); however, to-date no comparisons of the scarring response have been made. In addition, to the above models, work on farmed salmon (S. salar) [87] The giant zebrafish (D. aequipinnatus) [81], zebrafish (D. rerio) [8], goldfish (C. auratus) [82], killifish (N. furzeri) [62] and the eyed surface-morph of the A. mexicanus [83] have all been documented to regenerate their hearts after a variety of insults such as cauterisation [84], ventricular amputation, genetic ablation [85] and cryoinjury [86]. However, despite the close relation of the zebrafish to the giant zebrafish and the goldfish, only the killifish and the zebrafish have so far been compared for shared mechanisms of regeneration [62].…”

Reactive oxygen species during heart regeneration in zebrafish: Lessons for future clinical therapies

“…12 As coronary artery ligation has been precluded as a method of inducing myocardial ischaemia due to the small size of the zebrafish heart, alternative methods have been established, such as ventricular resection, ventricular puncture, cauterization, and cryoinjury. 28,[33][34][35] Cryoinjury, where a metal filament cooled in liquid nitrogen is applied to the ventricular surface of the heart to freeze an area, initiates tissue necrosis through fast freezing and thawing of cells. 35 The cryoinjury causes the cells surrounding the necrotic area to undergo apoptosis, 35 and deposition of fibrotic scar tissue via inflammatory cells is seen after the clearance of debris from cell death.…”