There's no safe way to get a close-up view of the human heart as it goes about its work: you can't just pop it out, take a look, then slot it back in.

Scientists have tried different ways to get around this fundamental problem: they've hooked up cadaver hearts to machines to make them pump again, and attached lab-grown heart tissues to springs to watch them expand and contract.

Each approach has its flaws: reanimated hearts can only beat for a few hours; springs can't replicate the forces at work on the real muscle.

But getting a better understanding of this vital organ is urgent: in America, someone dies of heart disease every 36 seconds. Now, an interdisciplinary team of engineers, biologists, and geneticists has developed a new way of studying the heart: they've built a miniature replica of a heart chamber from a combination of nanoengineered parts and human heart tissue.

Unlike past trials that used springs or external power sources, the new version just beats by itself, driven by the live heart tissue grown from stem cells. The device could give researchers a more accurate view of how the organ works, allowing them to track how the heart grows in the embryo, study the impact of disease, and test the potential effectiveness and side effects of new treatments -- all at zero risk to patients and without leaving a lab.

The Boston University-led team behind the gadget officially known as the cardiac miniaturized Precision-enabled Unidirectional Microfluidic Pump -- says the technology could also pave the way for building lab-based versions of other organs, from lungs to kidneys. Their findings have been published in Science Advances on April 24.

"This tool helps us study disease progression in a way that hasn't been possible before. We chose to work on heart tissue because of its particularly complicated mechanics, but we showed that, when you take nanotechnology and marry it with tissue engineering, there's potential for replicating this for multiple organs,” says Alice White, a BU College of Engineering professor and chair of mechanical engineering.