Photo of a lab rat

It may soon be easier to test new heart drugs for safety and effectiveness. Scientists have created a miniature human heart by introducing human cells into the matrix of a whole rat heart. The tiny hearts could also make it easier to confirm basic science findings.

Researchers have long used the Langendorff method to remove the heart from an animal in order to introduce fluid through the aorta, the body’s largest vessel, then into the artery network of a heart. This method is also used to deliver solutions that strip away cells from the rat heart before introducing the human cells to model a human heart.

In the new study, researchers used a technique called 4-Flow cannulation, which introduces solution not just into the arteries but into the veins’ network of the heart. This system allowed the researchers to strip rat cells while preserving the lining matrix of the whole heart to repopulate with human cells. Unlike the Langendorff method, 4-Flow cannulation allowed the researchers to preserve the circulation within the entire heart to maintain the normal flow and, in addition, to stimulate the mechanical expansion of heart chambers.

The findings were presented Wednesday at the American Heart Association’s Basic Cardiovascular Sciences 2017 Scientific Sessions.