Explaining the reason for blood vessels' resistance to high pressure:

In a groundbreaking discovery, a team of researchers led by physicist Claire Dessalles from the University of Geneva in Switzerland have uncovered the intricate ways blood vessels adapt to increased pressure. Their findings, published in the June issue of Nature Physics, shed light on the behaviour of vessel cells on a microscopic level.

The study focuses on the endothelium, the thin inner layer of blood vessels, which contains thin strands of a muscle protein called actin. These strands can contract or relax, allowing the cells to flex and structurally adapt under pressure. This adaptation occurs with a "fluid-like expansion," a result of the nematodynamic action in the actin layer.

This research stands out due to its application of real pressure to a 3-D tube, rather than stretching cell layers in a flat, 2-D sheet, as was common in previous studies. Alisa Morss Clyne, a biomechanical engineer at the University of Maryland in College Park, notes this difference as a significant contribution to the field.

Without actin, the tissue becomes much softer and cannot handle pressure well, suggesting that actin is crucial for the strength of blood vessels. The study also revealed that the tiny thread-like proteins in cells lining blood vessels reorganize dramatically under increased pressure, behaving similarly to how liquid crystals do – having both fluid-like flow and some orderly structure.

The similar action observed in zebrafish when the heart starts to beat was "very exciting" for Dessalles and her team, as it highlights the universality of these findings. The researchers hope to expand their study to examine bigger vessels with muscle around them in the future, using their new model.

Nathan Sniadecki, a mechanical engineer at the University of Washington in Seattle, believes that this study will help us better understand how the human body changes over time, whether from aging or disease. Other scientists are interested in using the new 3-D model to study blood vessels in places such as the kidneys or lungs.

The tests conducted by Dessalles' team used only endothelial cells, which are found in tiny blood vessels like capillaries. The study was carried out on a tiny artificial blood vessel built in a dish, lined with human cells. Despite the advancements made, the study does not provide information about the identity of the researcher who published findings on changes in blood vessel cells related to high blood pressure.

This new understanding of blood vessel expansion could lead to improved treatments for conditions involving increased pressure in the cardiovascular system, offering a promising avenue for future research.