Human 'heart-on-a-chip' to help screen drugs

Researchers, including one of Indian-origin, have created a 'heart-on-a-chip' loaded with human cardiac muscle cells that mimic the real organ to serve as a novel tool to screen medicines.
Researchers developed a network of pulsating cardiac muscle cells housed in an inch-long silicone device that effectively models human heart tissue, and they have demonstrated the viability of this system as a drug-screening tool by testing it with cardiovascular medications.
This organ-on-a-chip represents a major step forward in the development of accurate, faster methods of testing for drug toxicity, researchers said.
"Ultimately, these chips could replace the use of animals to screen drugs for safety and efficacy," said professor Kevin Healy from the University of California, Berkeley.

The authors noted a high failure rate associated with the use of nonhuman animal models to predict human reactions to new drugs.
"It takes about 5 billion pounds on average to develop a drug, and 60 per cent of that figure comes from upfront costs in the research and development phase. Using a well-designed model of a human organ could significantly cut the cost and time of bringing a new drug to market," said Healy.

The heart cells were derived from human-induced pluripotent stem cells, the adult stem cells that can be coaxed to become many different types of tissue.

The researchers designed their cardiac microphysiological system, or heart-on-a-chip, so that its 3-D structure would be comparable to the geometry and spacing of connective tissue fibre in a human heart.
The system's confined geometry helps align the cells in multiple layers and in a single direction.
Microfluidic channels on either side of the cell area serve as models for blood vessels, mimicking the exchange by diffusion of nutrients and drugs with human tissue.
In the future, this setup could also allow researchers to monitor the removal of metabolic waste products from the cells.
"This system is not a simple cell culture where tissue is being bathed in a static bath of liquid," said study lead author Anurag Mathur, a postdoctoral scholar in Healy's lab and a California Institute for Regenerative Medicine fellow.

"We designed this system so that it is dynamic; it replicates how tissue in our bodies actually gets exposed to nutrients and drug," said Mathur.
Within 24 hours after the heart cells were loaded into the chamber, they began beating on their own at a normal physiological rate of 55 to 80 beats per minute.
The research was published in the journal Scientific Reports.