BioEssays 12/2024

Human pluripotent stem cells can differentiate to all cells of the body, including those of the heart. The heart contains multiple cell types but the contractile cells are called cardiomyocytes. In article 2400078, Christine Mummery describes her serendipitous finding on how to induce differentiation of human embryonic stem cells into cardiomyocytes by co‐culture with visceral endoderm. This was later reproduced in human induced pluripotent stem cells using growth factors. The contractile apparatus of cardiomyocytes, which consists of structures called sarcomeres, is clearly evident in these cells after antibody staining. hiPSC can be derived from patients with different cardiac diseases. Cardiomyocytes from these hiPSC often capture patient phenotypes. This has led both to new insights into mechanisms underlying genetic cardiac diseases, like myopathies or arrhythmias, and created opportunities for discovering new drugs to treat these conditions and to assess their cardiac safety, without using animal models. The image shows immunofluorescent staining of sarcomeres, the contractile units of the human heart, in cardiomycytes derived from human induced pluripotent stem cells. Staining is for cardiac Troponin T (green) and α‐sarcomeric actinin (red). Nuclei are stained blue with Hoechst. Credit to Viviana Meraviglia.