MAY 24, 2018 9:32 PM PDT

How Zebrafish Reveal The Truth About The Human Heart

WRITTEN BY: Nouran Amin

The development of the Zebrafish has revealed the blueprint for the chambers of our human heart. The discovery has revealed the truth about the processes involved in congenital heart defects this has made the zebrafish the ultimate heart model for future research that mimics what exactly happens in the development of the human heart.

During development, the four chambers of the heart are formed to support the flow of blood to the lungs and the rest of the body. The organization of these blood systems is essential for the evolution of mammals descending from aquatic ancestors. However, the processes by how the left and right cardiac compartments are distinguished remain poorly understood.

Investigation into the human heart has shown that the development of the adult heart occurs from two types of precursor cells known as first heart field (FHF) and second heart filed (SHF). The FHF cells compose most of the left ventricle, whereas SHF shapes most of the right ventricle. Regardless of this type of development, both left and right atriums include the cells from both FHF and SHF.

"This suggested that the left and right sides of the ventricle and atrium of the heart are developed by different biological processes, to ensure distinction between the side that supports the lungs, and the side that supports blood flow to the rest of the body," notes Dr. Almary Guerra, a graduate student at the Max Planck Institute for Heart and Lung Research, Germany, and lead author of the research paper. "But given that the same cells are involved in both sides of the atrium, we still do not understand how the left and right parts of the atrium develop separately from each other."

Studies on the zebrafish has increased our knowledge of heart development which explains the reason behind Dr. Guerra and colleagues using this particular animal model to investigate the molecular and cellular differences between the two sides of the single atrium.

Investigators first sought the genes that were activated mostly in the atrium. This lead to two particular genes of interest: pitx2c and meis2b. It is known that mutations in the human versions of these genes can lead to significant heart defects in the development of the septum. To examine pitx2c and meis2b, investigators found that the most active gene in the cell populations present in the left atrium, during the earliest stages of development, was meis2b. Interestingly, the SHF precursor cells involved in the development of the atria were present in regions where meis2b was both present and absent. This confirmed that SHF is an equal contributor to both sides of the atrium and not involved in the asymmetric development of the atrium.

Asymmetrical cardiac expression of the meis2b gene at early stages of embryonic heart development in zebrafish. Credit: Almary Guerra via Science Daily

"We have shown for the first time that atrial compartmentalization occurs in the zebrafish," explains senior author Dr, Sven Reischauer, Junior Group Leader at the Max Planck Institute for Heart and Lung Research. "The next step is to identify the specific elements that control atrial asymmetry and to use the model to reveal further insights into heart development that will be invaluable for understanding and treating heart defects."

Source: Science Daily 

About the Author
Doctorate (PhD)
Nouran is a scientist, educator, and life-long learner with a passion for making science more communicable. When not busy in the lab isolating blood macrophages, she enjoys writing on various STEM topics.
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