13 October 2022

Thesis defense Hessel Honkoop: “Uncovering the road towards cardiomyocyte proliferation”

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Hessel Honkoop, from the group of Jeroen Bakkers, has successfully defended his thesis “Uncovering the road towards cardiomyocyte proliferation: A spatial and temporal analysis of zebrafish heart regeneration” on 13 October 2022. In his thesis, he studies how the zebrafish restores heart tissue that has died, for example due to a heart attack. A better understanding of how the zebrafish manages this, could in the long run also improve the treatment of patients with heart disease.

Cardiovascular diseases are the number one cause of death in the Western World. Among this group of diseases, heart attacks are common. During a heart attack, the blood supply to the heart is cut off, preventing oxygen and nutrients from reaching certain parts of the heart. This causes millions of heart muscle cells to die, which creates a scar. The scar hinders the contraction of the heart, thereby deteriorating heart function.

New tissue

People cannot restore tissue lost from a heart attack; the resulting scar is permanent. Surprisingly, this is different in zebrafish. Within 30 days after a heart attack, they have already replaced the lost heart tissue and restored their heart function. Zebrafish use a unique mechanism that causes adult heart muscle cells to divide and thereby produce new cells to replace the lost ones. In his thesis, Hessel Honkoop investigates exactly how these heart muscle cells do this and which processes underlie this mechanism.

Learning from the zebrafish

By studying zebrafish, Honkoop and his colleagues learned more about how heart muscle cells divide and how the zebrafish heart makes new tissue. “Hopefully we can use this information to eventually stimulate the division of heart muscle cells in people, in order to improve the recovery of the heart after a heart attack.” But before that, more research is needed to find out if and how the results obtained through studies with zebrafish can be translated to humans.

Ups and downs

Honkoop considers himself lucky with the lab where he completed his PhD and the helpful colleagues that surrounded him. There was also a lot of room for personal development during his PhD. He would advise prospective PhD students: “A PhD comes with highs and lows, in which the latter sometimes seem to take the upper hand. It is important not to forget the highs and to keep the end goal in sight.” He also advises young researchers to participate in all activities that are organized, such as borrels and master classes. “These activities make your promotion at the Hubrecht a great time,” says the brand-new doctor.

Portrait picture Hessel Honkoop




To celebrate his promotion, Hessel Honkoop is throwing a party in the center of Utrecht. The next step in his career is still undecided.