The outer curvature of the heart faces a lot of pressure. It’s right across from the valve where blood enters, getting hit with incoming blood. Researchers thought specific genes were key to how this area developed, but when Priya and her student Christopher Chan looked into it, they found something surprising: the expected enzymes weren’t there. This led them to consider physics instead of just genetics.
Using zebrafish, Priya and Chan captured the heart’s formation with high-speed imaging. Six hours after the heart began to beat, they discovered gaps in the cardiac jelly—a protein network that supports heart tissue. These gaps spread like cracks, and a day later, strands of trabeculae started to form in these spaces, suggesting a link between the gaps and trabeculae development.
They asked computational scientist Daniel Santos-Oliván to run simulations of beating hearts. These models confirmed the gaps were fractures, showing how the heart’s pulsing creates stress that weakens the jelly scaffold until it breaks. When the fractures occur, heart muscle cells detach from the wall and dive into the jelly’s gaps, helping to form trabeculae. Priya noted that this geometric process was unexpected.
To test their idea, they altered the zebrafish heart rate. More fractures appeared with faster heartbeats, while fewer showed up when the heart rate slowed. This provided proof that the fracturing depended on the heart’s contractions. Additionally, when the team engineered the hearts to grow differently, the fractures adapted in response, further confirming their findings.
Interestingly, Priya’s team has also spotted similar fractures in chicken embryos. This raises the possibility that human hearts might be shaped through similar mechanical processes. Their ongoing work with zebrafish shows that physical forces can play a crucial role in developing vital organs, often ahead of genetic factors.
The idea that fractures can aid in development is intriguing. While this might not be common, it occurs in various animals. Fractures shape zebrafish nostrils, hydra mouths, and even fruit fly legs. Though fractures seem damaging, they might play a constructive role in tissue formation, a concept detailed in a recent review paper co-authored by Priya and her team.
Milinkovitch, an expert in evolutionary mechanics, suggests that as researchers become aware of these fracturing methods, they might find even more examples. Besides fracturing, living tissues can crumple, buckle, wrinkle, and fold, showcasing nature’s ingenuity. Understanding these physical mechanisms could clarify how evolution works, making it easier to grasp the complexity of development.
You can dive deeper into this research through the ongoing work from Quanta Magazine, which captures the intriguing intersection between biology and physics in heart development.
