A “heart-on-a-chip,” built by UC Berkeley bioengineers, houses human heart tissue derived from adult stem cells. The system could one day replace animal models for drug safety screening.

The Berkeley team presented a network of pulsating cardiac muscle cells within an inch-long silicone device. The researchers designed their cardiac microphysiological system so that its 3-D structure would be comparable to the geometry and spacing of connective tissue fiber in a human heart. The system’s confined geometry helps align the cells in multiple layers and in a single direction.

Within 24 hours after the heart cells were loaded into the chamber, the cells began beating on their own at a normal physiological rate of 55 to 80 beats per minute. 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.

The heart-on-a-chip could be adapted to model human genetic diseases or to screen for an individual’s reaction to drugs.

The project is funded through the Tissue Chip for Drug Screening Initiative, an interagency collaboration launched by the National Institutes of Health to develop 3-D human tissue chips that model the structure and function of human organs.