The University of Massachusetts Amherst
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Juan Jiménez Receives Grant to Study the Healing Role Played by Implanted Stents

Juan Jiménez

Juan Jiménez 

Juan Jiménez, an assistant professor in the Mechanical and Industrial Engineering Department and an adjunct in the Biomedical Engineering Department, has been awarded $147,849 by Stryker Neurovascular to study how different properties of stents play a role in healing after stents are used clinically to treat intracranial atherosclerotic lesions.

The development, progression, and complication of these intracranial atherosclerotic lesions, affecting the large arteries in the cranial region, are a major cause of stroke occurrence and recurrence. A stent is a tiny wire mesh tube that props open an artery and is left there permanently after an artery has been narrowed by a buildup of fatty deposits called plaque.

In the case of intracranial atherosclerotic disease, stents help keep arteries open, increase blood flow through the arteries, and reduce the chance of a stroke.

“Unfortunately,” explains Jiménez, “stents harm the vessel during deployment, and healing can be affected by the design of the stent. The Jiménez group will be studying different stent properties that may affect healing.”

As Jiménez observes about these laboratory experiments, “They are a necessary first step to elucidate which stent variables delay or inhibit healing after deployment.”

As background for his research, Jiménez explains that intracranial atherosclerotic disease tends to occur concurrently with systemic atherosclerosis in other arterial beds, where it has been shown that the temporal characteristics of wall shear stress play a major role in the susceptibility, development, and progression of the disease.

In addition, “The temporal characteristics of hemodynamic wall shear stresses are further affected upon deployment of stents to treat atherosclerotic lesions,” says Jiménez.

Jiménez adds that it has been recently demonstrated in his laboratory that the effects of both the bulk blood flow and the resulting local field of blood flow due to the geometry of the stent strut are important in the regeneration of endothelial tissue, the primary marker for clinical success after a stent has been implanted.

According to Jiménez, understanding the effects of stent design on the flow field and consequent reendothelialization after stent implantation is paramount to improving clinical success. In this context, early in the design process, stents can be tested in vitro to determine their effect on reendothelialization and cytocompatibility, meaning their compatibility with human cells.

As Jiménez explains how his experiments are applicable to real human cerebral arteries implanted with stents, “The endothelial cells that line the inner layer of blood vessels are highly responsive to not only the material properties of the stent, but also to the mechanical stresses imparted by the blood flow. In addition to using stents that are deployed clinically, we recreate in vitro the physiological mechanical stresses experienced in a cerebral artery and measure metrics related to healing in an in vitro artery model.”

In general, the Jiménez Research Group studies the interaction between fluid flow and biology by integrating fluid dynamic engineering and cellular and molecular biology. The research focuses on biofluids, such as blood and lymph, which continuously interact with endothelial cells in the body eliciting biochemical and physical responses.

“Our research seeks to elucidate the fluid flow characteristics and fluid flow-dependent biomolecular pathways relevant in medicine,” says Jiménez.