Does time heal all wounds? Damage in blood vessels

It is most important in medicine not to cause harm. A common side effect of surgical interventions, however, is mechanical overloading of the affected and/or the surrounding tissue. This can lead to a remodeling of the tissue, which requires a new intervention. Research aims to find a way to reduce trauma. This can be achieved through less invasive techniques and by designing less traumatic devices. The effectiveness of techniques and design depends on how well damage mechanisms in the cardiovascular tissue are understood and how these can then be translated into objective design criteria. One goal of this project is therefore to create a precise mathematical representation of a blood vessel by including microstructural and mechanobiological information. This representation can then be used to virtually test surgical interventions in order to optimize interventions and minimize acute and long-term damage. This requires a collection of tissues, their microstructural analyzes, multi-axial mechanical tests and nonlinear numerical modeling. This is performed by a unique international consortium, with experts in each of these areas.

Cardiovascular diseases remain the leading cause of death worldwide, despite advances in medical treatments. Our research focuses on improving surgical procedures used to treat arterial diseases, particularly atherosclerosis, a condition where the arterial lumen narrows due to plaque buildup, restricting blood flow. To restore blood flow, physicians commonly perform balloon angioplasty or stenting, both of which mechanically stretch the artery. While these procedures are life-saving, they often lead to restenosis, the re-narrowing of the artery over time. One of the key contributors to restenosis is mechanical overstretching during the procedure, but the biological response of arterial tissue to this overstretching remains poorly understood. This research aimed to develop and assess methods for analyzing this response. We focused on building a framework for material modeling and simulation, supported by experimental techniques that provide critical input for these models. While current material models can mathematically describe how a specific arterial tissue behaves using pre-obtained mechanical data, they cannot predict how a different tissue sample will respond. To improve the predictive ability of these models, we evaluated various modeling approaches and investigated how structural parameters, such as collagen fiber damage, influence tissue behavior under mechanical stress. Notably, accurate experimental assessment of these structural parameters remains a challenge. Collagen fibers, which provide strength to arterial walls, undergo damage when overstretched, influencing how the artery reacts to surgical intervention. However, capturing detailed images of these fibers requires advanced microscopy techniques, which involve complex sample preparation that may alter tissue properties. This creates a challenge in balancing accurate imaging with preserving tissue integrity. To address this, we reviewed and refined existing imaging and testing techniques to allow for a more reliable analysis of structural parameters, including collagen fiber damage and its correlation with mechanical forces. While it is well known that tissue structure influences arterial mechanics, the specific structural parameters that drive this response are not yet fully understood. Gaining this knowledge is critical to improving surgical procedures such as balloon angioplasty and stenting, with the goal of reducing restenosis rates and enhancing long-term patient outcomes. Our study provides new insights into how mechanical overstretching affects arterial tissues, contributing to the development of more effective treatments for cardiovascular diseases.