"Circulatory system on a chip lets scientists mimic heartbeat."

A tiny chip that mimics a circulatory system—right down to the rhythm of a human heart beat—could be an invaluable tool in understanding the causes of cardiovascular disease and developing drug therapies.

The system of tiny valves and channels on the chip mimic blood flow in the body, said biomedical engineering professor Shuichi Takayama, corresponding author of the paper, "Computer Controlled Microcirculatory Support System for Endothelial Cell Culture and Shearing," scheduled to appear in July in the journal Analytical Chemistry.

The design lets scientists study the fluid mechanical effects of blood flow (called shear stress) in certain cells that play a critical role in heart disease. The cells, called endothelial cells, line the inner walls of blood vessels. The changes in ECs caused when blood flows past them at different speeds and rhythms are at least partly responsible for fueling certain diseases—including cardiovascular disease.

Studying endothelial cells in a Petri dish is often ineffective because the test environment is static, like bath water, said Takayama, so the cells are not acting as they would in the body where they are exposed to flow, like in a river. But with the U-M system, scientists can adjust the flow through the channels on the chip so that the ECs think they are inside an artery or vein, or maybe even inside the blood vessels of a couch potato or a regular exerciser, Takayama said.

The system is also capable of mimicking the irregular, surging flow of blood pumped by the heart. A big question in the study of heart disease and cardiovascular research is how these endothelial cells sense and convert the fluid mechanical stresses associated with blood flowing past the cell into diseases, such as hardening of the arteries or thrombosis. Answering those questions will provide big clues to developing therapies to regulate ECs.

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