LAKE WALES, Fla. — Instead of dissecting rats or culturing sacrificial heart cells in petri dishes, medical researchers may be able to study the causes of cardiovascular disease and ways to prevent it using a microelectromechanical system (MEMS) microfluidic chip developed at Nanyang Technological University in Singapore.
The chip mimics the blood flow in delicate arteries when fat and cholesterol accumulate as plaque on the interior arterial walls. In living tissue, the resultant atherosclerosis restricts blood flow and can cause a heart attack. The key to the chip is its ability to model the inflammatory responses of heart vessel cells that cause them to cut off the blood supply. If those responses can be suppressed, then a heart attack will not occur.
In the study, the researchers first used artificial blood to perfect the flow through the microfluidic “vessels” and then used real blood to initiate the inflammatory responses that need to be eliminated to prevent heart attacks. Because the responses of the cells lining the blood vessels can be closely observed in the chip, the research team claims its modeling approach for atherosclerosis is vastly superior to methods that model the condition using cultured cells or lab animals.
The team hopes to learn how to regulate vessel constriction by various means in order to prevent or at least mitigate heart attacks. The researchers thus far have concentrated on the overall biomechanics of blood flow in the heart and on accurately modeling the shape and geometry of the heart’s blood vessels in order to pinpoint the causes of constriction.
The square-inch chip uses two stacked chambers, separated by a flexible polymer membrane, to simulate the conditions leading to a heart attack. The bottom chamber contains compressed air. The top chamber contains the blood (or bloodlike test fluid). To model a real heart accurately, the researchers cultured endothelial cells from coronary veins to line the fluid-filled chamber. The system operates by pumping air into the flexible air-filled chamber, thus pushing the membrane to mimic the restricted blood flow in a clogged artery.
Atherosclerosis-on-a-chip models stenosis
and assesses blood health before heart attacks.
Source: Han Wei Hou
The researchers found that as the clogging action increased, the endothelial cells emitted the same protein that develops atherosclerosis. When real blood was used, the immune cells accumulated the lipids that develop into artery-clogging plaque even more quickly.
The chip’s accuracy in mimicking these well-known precursors to heart attacks make it an ideal device for testing new treatments, according to team leader Han Wei Hou.
The team reports its results in “Atherosclerosis-on-a-Chip: A Tunable 3D Stenotic Blood Vessel Microdevice” and in an article publishing today (Jan. 2): “A tunable microfluidic 3D stenosis model to study leukocyte-endothelial interactions in atherosclerosis.”
— R. Colin Johnson, Advanced Technology Editor, EE Times