Human stem cells have been coaxed to form structures that resemble tiny, primitive, beating hearts by altering the mechanical and biochemical signals that they receive, reports a paper published in Nature Communications. It is thought that the structures will aid the study of normal and abnormal cardiac development and could find use in drug development as ‘organs on a chip.’

Kevin Healy, Bruce Conklin and colleagues etched physical patterns into the base of tissue culture dish then used them to grow colonies of human stem cells in chemically-defined media. They found that the stem cells differentiate into different cardiac cell types including heart muscle cells and the different cells self-organised themselves into beating cardiac microchambers.

When exposed to the drug thalidomide, a drug known for its adverse effects on embryonic heart development, the forming microchambers failed to develop properly, highlighting a potential role for the tissue culture system in drug screening. Similar systems already exist but these use two- rather than three-dimensional cultures of cells and so are unable to predict how drugs may affect the normal 3-D development of the embryonic heart.