A novel platform for unraveling the role of the primary cilium in heart regeneration

K. Apolinova1,4, S. Dyballa1, B. Coppe3, C. Jung2, N. Mercader Huber3, V. Di Donato1, J. Terriente1, 2. 1 ZeClinics SL, Badalona, Spain; 2 ZeCardio SL, Badalona, Spain; 3 University of Bern, Department of Developmental Biology and Regeneration, Bern, Bern, Switzerland; 4 University Pompeu Fabra, Department of Medicine and Life Science, Barcelona, Spain.


Cardiovascular diseases remain the leading cause of death worldwide, and few effective treatment options are available. Heart injury, such as myocardial infarction, causes irreversible damage to the heart muscle and its replacement by scar, leading to a chronic decrease in heart function. In contrast to humans, the injured zebrafish heart muscle regenerates efficiently through the robust proliferation of myocardial cells. Thus, the zebrafish presents a beneficial vertebrate model for studying genetic programs behind cardiac regeneration, which may be present, albeit dormant, in the adult human heart.

Recently, a link between cardiomyocyte regeneration and the primary cilium has been identified but remains poorly defined. Exploring the role of the cilium in heart regeneration will allow us to better understand the signaling networks behind heart regeneration, potentially leading to the identification of druggable targets in order to facilitate better cardiomyocyte regeneration in the human heart.

To this end, we established a novel medium-throughput platform for studying heart regeneration after cardiomyocyte ablation in zebrafish larvae. The specific ablation of cardiomyocytes is achieved through a transgenic construct inducing the expression of nitroreductase in a pool of ventricular cardiomyocytes. Subsequent treatment with a pro-drug induces a loss of >90% of nitroreductase-expressing cardiomyocytes, which are replaced through the proliferation of remaining cardiomyocytes within 4 days post injury. Our results further show that treatment with known anti-regenerative molecules causes a significant delay in regeneration kinetics, providing proof of principle for this platform in identifying anti-regenerative effects of genes and drugs. In combination with a powerful CRISPR/Cas9-driven approach for the knockout of ciliary genes of interest in zebrafish larvae, this platform can be used for fast medium- throughput screening of genes with presumed effects on regeneration. Using this platform, we aim to discover therapeutic targets that will allow us to activate the dormant regenerative potential of the human heart.

A novel platform for unraveling the role of the primary cilium in heart regeneration