Pete and Mayo Clinic discover a new and immediate phase of vascular restructuring after aneurysms
Hitting a hole on the road the wrong way could cause a tire to bulge, which is a weak spot that will definitely lead to a puncture in the tire eventually. But what if this tire immediately begins re-woven the rubber, which strengthens the bulge and prevents it from bursting?
This is exactly what blood vessels can do after an aneurysm forms, according to new research led by the University of Pittsburgh’s Swanson School of Engineering and in partnership with the Mayo Clinic. Aneurysms are abnormal bulges in artery walls that can form in the arteries of the brain. A ruptured brain aneurysm is fatal in about 50% of cases.
The research was recently published in Experimental MechanicsHe is the first to demonstrate that there are two phases of wall restructuring after the aneurysm has formed, the first being to immediately strengthen weak spots.
Imagine extending a rubber tube in one direction such that it only needs reinforcement for loads in that direction. However, in an aneurysm, the forces change to resemble those of a spherical balloon, pulling forces in multiple directions, making it more likely to explode, explains Ann Robertson, a professor of mechanical engineering and materials science at Pitt, whose lab led the research. Our study found that blood vessels are able to adapt after the aneurysm has formed. They can restructure their collagen fibers in multiple directions instead of just one, making them better able to handle new loads without tearing. “
Researchers have known that blood vessels have the potential to change and restructure over time, but this study represents the first observation of a new initial phase of restructuring that begins immediately.
The researchers used a rabbit model developed by David Calms of Mayo Clinic to observe the restructuring of brain tissue over time. To see this process up close, the researchers partnered with Simon Watkins at the Pitt Biological Imaging Center, leveraging the center’s state-of-the-art microscopes to image the fiber structure within the aneurysm wall.
“We found that the first stage of restructuring involves placing a completely new layer of collagen fibers in two directions to better deal with the new pregnancy, while the second phase involves remodeling the existing layers so that their fibers fall in two directions,” Zhao Sang explained, who was a lead researcher at This research is part of a PhD thesis in the Department of Mechanical Engineering and Materials Science at Pete
“Long-term restructuring is like forming a scar after wound healing, whereas this first stage that we observed can be considered to play a similar role to clotting immediately after a wound – the body’s first response to protect itself,” added Robertson, who got a secondary appointment in the bioengineering department at Swanson School. “Now that we know this first stage, we can begin to investigate how it is enhanced in patients with aneurysms, and how factors such as age and pre-existing conditions affect this ability and may put the patient at greater risk for an aneurysm rupture.”
The investigation team includes Robertson and graduate students Zhao Sang and Michael Durka of Pitt, Simon Watkins of the Biological Imaging Center, David Calms, Ramanathan Caderville, Young Hong Ding and Ding Dai of the Mayo Clinic Radiology Department.
The paper “Adaptive Remodeling in the Elastase-induced Rabbit aneurysms” (DOI: 10.1007 / s11340-020-00671-9) is published in the journal Experimental Mechanics It was written by Chow Sang, Michael Durka and Ann Robertson at Swanson School. David Calms, Ramanathan Caderville, Young Hong Ding and Ding Dai in the Mayo Clinic Radiology Department; Simon Watkins at the Pitt Biological Imaging Center.
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