In this podcast episode, MRS Bulletin’s Sophia Chen interviews graduate student John Ahrens of Harvard University about challenges in bioprinting heart tissue. One challenge in particular is aligning the cells. Heart cells are narrow and rectangular in shape. In a natural heart, they line up in parallel to form aligned filaments. Those aligned filaments are built up into a larger tissue with more complex alignment. Cellular alignment correlates with heart function. The research team has programmed the bioprinter to make tissues that are aligned vertically, in a circular pattern, or in the shape of a chevron. This study is published in Advanced Materials (doi:10.1002/adma.202200217).