Robert M. Berne
Cardiovascular Research Center
![October 2007
Inside Out: U.Va. Engineering School and School of Medicine Researchers Unite to Create First Realistic Intra-Vascular Environment to Better Understand Cell Responses to Early-Stage Atherosclerosis
HemoShear 2.0 is first human-based cellular co-culture system to model earliest stages of vascular heart disease outside of the human body
By: Andrea Arco
At any given second, the human body is performing thousands of functions and enabling millions of processes. In the circulatory system alone there are a variety of cells and organs interacting with — and affecting — each other on an almost constant basis. Although these interactions could potentially hold the key to understanding disease onset, improving diagnoses and creating efficacious treatment plans, they have proven difficult to study. Emulating the body’s complex processes realistically in the lab has been impossible — until now.
U.Va. researchers Brett Blackman, assistant professor in the Department of Biomedical Engineering, and Brian Wamhoff, assistant professor in the Department of Medicine (Cardiovascular Division), have teamed up to create a novel human cell-based model to study heart disease outside of the human body. Specifically, the model is used to study atherosclerosis — a disease affecting arterial blood vessels that causes hardening and narrowing of the arteries and that can lead to heart attack or stroke. An inflammatory disease, atherosclerosis tends to occur at locations in the arteries where blood flow is compromised and the altered shear stress — or the stress of the blood flow acting tangential to the walls of the blood vessels — causes endothelial cells (the cells lining the interior of blood vessels) and smooth muscle cells (the cells found in the wall of blood vessels) to undergo detrimental changes.
The researchers’ device, HemoShear 2.0, exposes human endothelial and smooth muscle cells (or any other type of cells the researcher wishes to pair with endothelial cells) to pulsatile features of blood flow in the human body (i.e. hemodynamic blood flow). The device also allows for the data from this exposure to be measured and recorded.
“By using the data on the velocity of blood in different arteries as obtained by MRI,” says Blackman, “we are able to simulate actual flow patterns in atheroprone areas [bifurcating and bulbous areas like the internal carotid that are more susceptible to atherosclerosis] and atheroprotective areas [pipe-like arteries like the common carotid that are less susceptible to atherosclerosis] and observe how the cells respond to these flow patterns.”
That is something, Wamhoff adds, that has never been done before. “Research has been conducted wherein human cells are isolated to observe behavior patterns, but there are no available models that allow one to accurately study the intricate communication between endothelial cells and smooth muscle cells in a setting that mimics hemodynamic blood forces in the body.”
This communication is important, considering that endothelial cells recognize different blood flow patterns imposed upon them and respond by expressing or repressing genes and that this, in turn, influences their interactions with the smooth muscle cells — interactions that, the researchers found, may lead to the onset of early-inflammation-associated atherosclerosis in arteries with altered shear stress.
Using HemoShear 2.0, the researchers mimicked atheroprone and atheroprotective circulatory environments. Endothelial cells were plated on the top surface of a synthetic elastic lamina (similar to a real blood vessel wall) and smooth muscle cells were plated on the bottom surface. Then, either atheroprone or atheroprotective arterial flow patterns modeled from human circulation were applied to the endothelial cells through rotation of a motor-driven cone system. The findings: hemodynamic flow can influence both endothelial and smooth muscle cell behaviors.
In the presence of atheroprotective flow, the endothelial cells aligned with the direction of the blood flow, and the smooth muscle cells aligned perpendicularly to the flow direction identical to the cellular orientation in a healthy blood vessel. In stark contrast, atheroprone flow caused the endothelial cells to move away from their parallel structure, and smooth muscle cells to move away from their perpendicular structure. This remodeling mimics the early phases of the diseased state of the artery. Atheroprone flow induced an inflammatory phenotype in both cells reminiscent of early hallmarks of atherosclerosis. This was confirmed through evaluating gene and protein expression profiles in both cell types.
"The results of this study validate the use of this novel co-culture system as a relevant biometric vascular model for studying early atherosclerotic events," says Tom Skalak, professor and chair of the U.Va. Department of Biomedical Engineering. "The cells' responses to these carefully controlled shear stresses can now be used to develop therapeutic interventions for detection and treatment of vascular diseases — it has the potential to be revolutionary."
Revolutionary, indeed. And drug companies are already taking notice. HemoShear 2.0 is a product unlike any before it that can help test the efficacy of therapeutic compounds and aid in early stage toxicity studies. Instead of testing drug compounds on isolated cells which can produce false negatives, drug companies can now test compounds in a more realistic in vitro environment, resulting in more meaningful data — and less time wasted.
Collaboration was key to the success of this product, and the research it makes possible. According to Dr. Sharon Hostler, Interim Dean and Vice President at the University of Virginia School of Medicine, "The exciting research done by Drs. Blackman and Wamhoff is a testament to the collaborative spirit found at the University of Virginia. Their work could hold the key in the area of translational research; shortening the time it takes for a new therapy or procedure to go from the laboratory bench to helping patients." In fact, the researchers have formed
a collaborative entity — the Laboratory of Atherogenesis — to begin using the HemoShear system to make these translatable discoveries in atherosclerosis.
Funding, too, was a collaborative effort. The research and product development was made possible by a U.Va. Fund for Excellence in Science and Technology (FEST) Award, provided by the Office of the Vice President for Research and Graduate Studies, and a U.Va. Heart Board Partner’s Fund Award administered through the Robert M. Berne Cardiovascular Research Center. Additional funding came from the Department of Biomedical Engineering’s Wallace H. Coulter Translational Partnership Award.
“There is a real need for biometric models like the one Professors Blackman and Wamhoff have developed,” says U.Va. Engineering School Dean James H. Aylor. “When collaborations among the intersecting fields of engineering, medicine and biotechnology occur, the potential innovations are limitless.”
A provisional patent has been filed for HemoShear 2.0. The research that HemoShear 2.0 made possible was spearheaded by a biomedical engineering graduate student, Nicole Hastings (’08), and has been accepted for publication in the American Journal of Physiology — Cell Physiology.
For more information, please visit the Laboratory of Atherogenesis at
http://faculty.virginia.edu/labofatherogenesis.
Related story in UVA’s Research News (July 2006)](news_pr_files/shapeimage_2.png)
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