When the heart beats, all of the muscle’s cells contract in unison in one smooth movement. Re-creating such synchronized motion in a petri dish (both for research and therapeutic purposes) poses a particular challenge, one that a research team from the Harvard-MIT Division of Health Sciences and Technology and the Draper Laboratory in Massachusetts met by taking inspiration from the humble accordion.

The researchers first tried tissue scaffolding (an ultrathin, biodegradable grid) with square- and rectangular-shaped pores, into which they seeded the heart cells from a newborn rat. Both pore shapes disappointed: Cells in the square pores didn’t grow in one direction as natural heart tissue does, whereas cells in the rectangular pores, despite aligning properly, were too stiff to move like normal heart tissue. The researchers then tried a design they named accordionlike honeycomb scaffolding, which combined the cell alignment of the rectangular design with the vertical and horizontal stiffness required to beat strongly and consistently. The cell-seeded scaffold mimicked natural heart tissue when electrical current was applied. The researchers don’t yet know why the accordion shape fosters more natural alignment than others.

Initially the team plans to use the scaffolding to grow artificial heart tissue with which to test new heart drugs. But damaged hearts are the real target of this technology; scaffolding impregnated with stem cells (which are able to proliferate, unlike adult heart cells) could be shaped into patches and, thanks to its flexibility and ability to disintegrate over time, placed on the heart’s surface, leaving the new, healthy cells to repopulate the damaged area.