Apex resection in Zebrafish: a Model for Heart Regeneration
Ischemic heart disease is one of the leading causes of deaths worldwide. A major hindrance to resolving this challenge lies in the mammalian heart’s inability to regenerate after injury, such as myocardial infarct. In contrast, zebrafish retain a regenerative capacity of the heart throughout their lifetime. Apex resection (AR) is a popular zebrafish model for studying heart regeneration, and entails resecting 10–20% of the heart in the apex region, followed by monitoring of the repair process until the heart is fully regenerated within 60 days.
In this publication the scientists describe in short videos the entire AR procedure step-by-step including anaesthesia, surgery, and recovery. They highlight that the concentration and duration of anesthesia are important parameters to consider for balancing necessary sedation levels while minimizing mortality.
The process of regeneration in zebrafish hearts is often evaluated in two dimensional (2D) tissue sections, as also shown in this study, the scientists hope to inspire others to develop new ideas on how to analyze heart repair using more unbiased 3D approaches. Even though histological and immunohistochemical stained sections provide valuable information of the regeneration process, the need for selection of individual heart tissue sections may bias the analysis. For instance, if one chooses to analyze the height of the ventricle to estimate myocardial outgrowth, the sections used should embrace the middle and largest part of the heart, which can be challenging in 2D views. Alternatively, 3D-analysis of cleared hearts may offer a more accurate assessment of where the resection site resides and how it is oriented.
In this paper the authors provide examples of how zebrafish heart regeneration can be assessed both in 2D (immunohistochemistry of heart sections) and 3D (analyses of whole, tissue cleared hearts using multiphoton imaging). Since the biological variation in zebrafish heart size is relatively high, the authors believe that the 3D-method presented here may improve the normalization of heart size to zebrafish body length or weight.
Overall, the AR model is an attractive model for studying heart regeneration, especially to gain insight into mechanistic differences between mammals and zebrafish, which may be translated back into mammals for improving repair after myocardial infarct.
In summary, this paper and its video guides aim to aid beginners in establishing and conducting the AR model in their laboratory, but also to spur further interest in improving the model and its evaluation.
This work is a result of a National collaboration initiative established by DanStem in 2017, with the aim to strengthen and develop basic research within the stem cell and developmental biology areas in Denmark.
Ellman, D. G., Slaiman, I. M., Mathiesen, S. B., Andersen, K. S., Hofmeister, W., Ober, E. A., & Andersen, D.C. (2021) Apex Resection in Zebrafish (Danio rerio) as a Model of Heart Regeneration: A Video-Assisted Guide. International Journal of Molecular Sciences, 22. doi: 10.3390/ijms22115865