Heartbeat on a chip to improve testing of cardiovascular drugs

A gravity-powered chip that can mimic a human heartbeat could advance pharmaceutical testing and open new possibilities in cell culture because it can mimic fundamental physical rhythms, scientists say.
The chip, developed by the University of Michigan researchers, uses an intricate network of microscopic, gravity-driven channels, capacitors and switches to make liquids flow across it in an unlimited variety of pulses and flow rates.
It enables researchers to test new therapies on human cell samples that have been injected into the device, in an environment that closely mimics conditions inside the body.
The first uses are likely to be in testing new cardiovascular drugs and blood thinners, where blood flow is critical to predicting performance, said Shuichi Takayama, U-M professor of biomedical engineering and macromolecular science and engineering who is one of the creators of the device.

"This chip gives us a bridge between the petri dish and the patient," Takayama said.
"Cells behave much more naturally when they're subjected to the pulsing rhythms inside the body, as opposed to sitting in a static environment in the lab.

"So, by duplicating those rhythms on a chip, we can perform much more accurate lab tests before we begin testing on patients," he said.
While previous devices have been able to recreate the pulse of a heartbeat outside the body, they required the use of a syringe pump operated by a lab technician, which made long-term tests difficult.
The new device is much simpler to operate and can run unattended for long periods of time.

The steady input pressure also makes it possible to run multiple pulse rates and pressures on a single chip. This is a big step forward because it enables technicians to run multiple tests at once, Takayama said.
"Different types of patients have different pulse rates," he said.
"For example, a septic patient's heart may beat faster or one blood vessel may have a different flow rate than another. Those factors influence how a given therapy will affect a cell. We can now replicate those factors and many others on a single chip and run the tests simultaneously," he said.
Takayama said the chip can also be used to duplicate other biorhythms in the body, like signals within the brain and hormone delivery.

"For example, we generally study liver cells' response to insulin by giving them a big dose all at once," he said.
"But in the body, the liver gets insulin from the pancreas in a series of tiny pulses. We could use this chip to duplicate those pulses and create a much more accurate model of what's happening in the body," he added.
The team's findings are detailed in a study published in the journal Nature Communications.