Immediately following an aneurysm, blood vessels reinforce themselves by adapting collagen fibres to spread out the load, a study has found.
An aneurysm is an abnormal bulge in the artery wall that can form in brain arteries. Brain aneurysms that rupture are fatal in nearly 50% of cases. In a rabbit model, the researchers used cutting-edge high-resolution microscopes to observe changes within the aneurysm, and observed that new collagen fibres laid down to deal with the strain and existing ones were re-oriented. Blood vessels had already been known to be able to reform and restructure over time, but this kind of primary restructuring is the first time that it has been observed, happening immediately after an event. Instead of forming along the same direction, the blood vessels adapt to the different directions the new loads are in.
Professor Anne Robertson at the University of Pittsburgh’s Swanson School of Engineering explained: “Imagine stretching a rubber tube in a single direction so that it only needs to be reinforced for loads in that direction. However, in an aneurysm, the forces change to be more like those in a spherical balloon, with forces pulling in multiple directions, making it more vulnerable to bursting. Our study found that blood vessels are capable of adapting after an aneurysm forms. They can restructure their collagen fibers in multiple directions instead of just one, making it better able to handle the new loads without rupturing.
“The first restructuring phase involves putting down a layer collagen fibres in two directions to deal with the new load, and the second phase involves re-orienting existing layers to adjust to these two directions, explained Chao Sang, who was a primary investigator on this research as part of his doctoral dissertation.
“The long-term restructuring is akin to a scar forming after a cut has healed, while this first phase that we observed can be thought of as having a role similar to clotting immediately after the cut–the body’s first response to protect itself,” added Robertson, who has a secondary appointment in the Swanson School’s Department of Bioengineering. “Now that we know about this first phase, we can begin to investigate how to promote it in patients with aneurysms, and how factors like age and preexisting conditions affect this ability and may place a patient at higher risk for aneurysm rupture
Source: News-Medical.Net
Journal information: Sang, C., et al. (2020) Adaptive Remodeling in the Elastase-Induced Rabbit Aneurysms. Experimental Mechanics. doi.org/10.1007/s11340-020-00671-9.
