Kateřina Apolínová, Vincenzo Di Donato, Javier Terriente. ZeClinics - IGTP research centre, Barcelona (SPAIN).
Cardiovascular diseases remain the leading cause of death worldwide, and few effective treatment options are available. Therefore, repairing and regrowing an injured myocardium is one of the holy grails of regenerative medicine. In contrast with the human heart, the injured zebrafish heart regenerates efficiently through robust proliferation of myocardial cells, making it a beneficial vertebrate model for studying the molecular and cellular mechanisms behind cardiac regeneration.
An interesting link between the endocardial primary cilium, a microtubule-based organelle integrating many signaling inputs, and heart regeneration has been recently identified. The ciliary mechanosensory TRPV4-TRPP2 channel complex is activated upon sensing oscilallatory blood flow in the injured heart, leading to the activation of Notch pathway in the endocardium, and a subsequent non-cell autonomous activation of pro-regenerative pathways in the myocardium. However, the precise molecular pathways underlying this process are currently unknown.
In order to investigate the role of the primary cilium in heart regeneration, we firstly generated mutants in ciliary genes of interest using CRISPR-Cas9. These mutants exhibited phenotypes consistent with known cilia phenotypes in the zebrafish. Secondly, to determine the kinetics of heart regeneration in zebrafish larvae, we established a novel medium-throughput platform for genetic ablation of cardiomyocytes. Using automated heart imaging at different timepoints during regeneration, we observe that the injured heart is completely regenerated by 3 days post injury in control larvae. Lastly, by combining these two tools, we will be able to determine the kinetics of heart regeneration in larvae with impaired cilia function, the hypothesis being that their regenerative capacity will be reduced due to the lack of sensing of oscillatory blood flow.
Unraveling the role of the primary cilium in heart regeneration