Scientists reveal how the neural tube closes in early pregnancy

In a unique collaboration, researchers have decoded the mechanical forces that close the neural tube during the earliest stages of pregnancy. The study reveals that the neural tube doesn't just "grow" shut; it is physically pulled closed by a "purse-string" mechanism powered by cellular motors.

This breakthrough provides a quantitative framework for understanding why this process fails in one out of every 1,000 pregnancies, leading to severe birth defects like spina bifida.

Key Findings

• Interdisciplinary Breakthrough: By combining theoretical physics with biological imaging, the team "connected the dots" between developmental stages that were previously seen as separate events.
• Mechanical Origins of Birth Defects: The research suggests that neural tube defects may be caused by a mechanical failure in the "purse-string" tension or a lack of cellular coordination, rather than just genetic or nutritional factors alone.
• Beyond the Brain: This physics-based approach to biology can now be applied to other human development stages where force, motion, and timing are critical, such as heart formation or wound healing.

In about one out of every 1,000 pregnancies, the neural tube, a key nervous system structure, fails to close properly. Georgia Tech physicists are now helping explain why this happens, having uncovered the physics that drive neural tube closure in a pregnancy's earliest stages.

Working with collaborators at University College London (UCL), Georgia Tech researchers used computer models to reveal how, during early development, forces generated by cells physically pull the neural tube closed - like a drawstring. This discovery offers new insight into a critical process that, when disrupted, can result in severe birth defects such as spina bifida.

The researchers presented their findings in Current Biology.

The UCL team studied mouse embryos, which develop similarly to humans, and Georgia Tech researchers used that data to construct their models. From the data, they identified the fundamental physics mechanism that enables neural tube closure in part of the brain. This mechanism, called a "purse string," is made of actin, a pivotal protein that forms a cell's skeletal structure. As the purse strings tighten, the tube closes.

During neural tube closure, actin filaments form a ring around the opening and engage molecular motors - proteins that generate forces inside cells," he said. "As these motors pull on the actin, they generate tension that tightens the ring and draws the tube closed.

As the actin ring tightens, cells stretch and elongate, causing them to align and move together in a synchronized pattern, like a school of fish. This coordination allows the cells to move faster and more efficiently, increasing tension and driving a feedback loop that helps seal the neural tube.

The team built a computer model to show how this feedback loop leads to successful neural tube formation. Further research using the model could help explain why the neural tube fails to close.

Beyond neural tube development, the findings highlight the power of physics-based modeling to explain complex biological processes that can't be observed directly. The researchers say this approach could be applied to other stages of human development where forces, motion, and timing are just as critical.