Predicting an individual's risk of ischemic stroke is difficult because thrombosis embolization—the process of a blood clot detaching from the area where it formed and traveling to and then sticking in another blood vessel—is based on factors that are unique to each person. In a study publishing in the Cell Press journal Cell Biomaterials on July 23, researchers developed a tool to get around this challenge: an artery-on-a-chip platform that can replicate a patient's specific vascular structure and blood flow dynamics, called a "physical twin."
"This idea was born out of a critical clinical gap," says author Lining Arnold Ju of the University of Sydney in Australia. "We know that even patients at 'low risk' can suffer from severe or fatal strokes. We wanted to find a better way to predict this risk."
Ischemic strokes occur when a blood vessel supplying the brain is blocked, usually by a clot or fatty plaque. When vital blood and oxygen are cut off, brain cells die within minutes. For this reason, it's important to find new ways to predict who is at highest risk so that better interventions can be developed.
"Our work recreates precise, patient-specific carotid artery geometries," says Ju." The physical twin also uses cells that more closely mimic the dynamics of blood flow in these structures.
The researchers reconstructed carotid arteries from six patients with varying degrees of disease. They used computational fluid dynamics to calculate how blood flowed through each artery, revealing substantial differences in local blood flow despite similar levels of narrowing. After using a laser to create a small injury in the underlying collagen, they also observed strikingly different clotting behaviors depending on the artery's shape.
"Our findings suggested that three-dimensional vascular shape and local flow disturbances matter far more than simple narrowing," says first author Yunduo Charles Zhao of the Heart Research Institute in Newtown, Australia, who was motivated to shift his research toward predictive stroke diagnosis during his PhD, when his grandmother passed away from stroke.
"We hope these tools will allow us to study drugs aimed at reducing the risk of stroke and to eventually provide personalized treatments for each patient based on their anatomy."
The team is currently recruiting stroke patients for a clinical trial to evaluate how this technology can directly benefit underserved stroke patients. They say this technology also has the potential to study other cardiovascular conditions, including peripheral artery disease, deep-vein thrombosis, and aneurisms.
