Cardiac Microchambers (IMAGE) University of California - Berkeley Caption When spatially confined, differentiating human induced pluripotent stem cells self-organize into cardiac microchambers. Myofibroblasts are green, cardiomyocytes are red and the nuclei are blue. Cardiac microchambers can be used to study the toxicity of drugs that affect early human heart development. Credit Zhen Ma, UC Berkeley Usage Restrictions Editorial use only. 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.