Johns Hopkins Medicine researchers are collaborating with NASA to send human heart "tissue-on-a-chip" specimens into space. The project is designed to monitor the tissue for changes in heart muscle cells' mitochondria (their power supply) and ability to contract in low-gravity conditions. To develop the microengineered human heart tissue-on-a-chip, researchers begin with human induced pluripotent stem cells grown in the laboratory. Kim, his previous postdoctoral researcher Jonathan Tsui, and his doctoral student Devin Mair previously sent heart tissue into space in March 2020. The astronauts aboard the space station will also test whether any of three medicines can stave off the problems anticipated in space-bound heart cells.