New York, March 10 (IANS): for the first time, scientists - including an Indian American bioengineer - have developed a network of pulsating cardiac muscle cells housed in an inch-long silicone device that effectively models human heart tissue.

The team has 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.

"Ultimately, these chips could replace the use of animals to screen drugs for safety and efficacy," said professor Kevin Healy of University of California, Berkeley, who led the team.

"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.

"We designed this system so that it is dynamic. It replicates how tissue in our bodies actually gets exposed to nutrients and drugs," Mathur explained.

The study authors noted a high failure rate associated with the use of nonhuman animal models to predict human reactions to new drugs.

Much of the failure is due to fundamental differences in biology between species, the researchers explained.

"Using a well-designed model of a human organ could significantly cut the cost and time of bringing a new drug to market," Healy added.

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 3D structure would be comparable to the geometry and spacing of connective tissue fibre in a human heart.

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 researchers put the system to the test by monitoring the reaction of the heart cells to four well-known cardiovascular drugs.

The baseline beat rate for the heart tissue consistently fell within 55 to 80 beats per minute, a range considered normal for adult humans.

The researchers noted that their heart-on-a-chip could be adapted to model human genetic diseases or to screen for an individual's reaction to drugs.

The engineered heart tissue remained viable and functional over multiple weeks. Given that time, it could be used to test various drugs, Healy said.

The findings were published in the journal Scientific Reports.