US researchers have engineered a tiny living heart chamber replica that may help to more accurately mimic the real organ and provide a sandbox for testing new heart disease treatments.

The miniature replica was built from a combination of nanoengineered parts and human heart tissue. There are no springs or external power sources -- like a real heart, it 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.

According to researchers at the Boston University who developed the gadget -- nicknamed miniPUMP, and officially known as the cardiac miniaturised Precision-enabled Unidirectional Microfluidic Pump, 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.

"We can study disease progression in a way that hasn't been possible before," said Alice White, a BU College of Engineering professor. "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 has the potential for replicating this for multiple organs," she added.

The researchers said the device could eventually speed up the drug development process, making it faster and cheaper. Instead of spending millions -- and possibly decades moving a medicinal drug through the development pipeline only to see it fall at the final hurdle when tested in people, researchers could use the miniPUMP at the outset to better predict success or failure.

At just 3 square centimetres, the miniPUMP isn't much bigger than a postage stamp. Built to act like a human heart ventricle --A or muscular lower chamber its custom-made components are fitted onto a thin piece of 3D-printed plastic.

There are miniature acrylic valves, opening and closing to control the flow of liquid -- water, in this case, rather than blood -- and small tubes, funnelling that fluid just like arteries and veins. And beating away in one corner, the muscle cells that make heart tissue contract, cardiomyocytes, made using stem cell technology.

To print each of the tiny components, the team used a process called two-photon direct laser writing -- a more precise version of 3D printing. When light is beamed into a liquid resin, the areas it touches turn solid; because the light can be aimed with such accuracy -- focused to a tiny spot -- many of the components in the miniPUMP are measured in microns, smaller than a dust particle.