Kate Rubins, NASA (IMAGE) NASA/Johnson Space Center Caption The Heart Cells investigation uses human skin cells that are induced to become stem cells, which can then differentiate into any type of cell. Researchers forced the stem cells to grow into human heart cells, which NASA astronaut Kate Rubins cultured aboard the space station for one month. Credit NASA Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.