Scientists in Shanghai have used stem cells to create the world’s first laboratory-grown sinoatrial node – the tiny structure that acts as the heart’s natural pacemaker. Capable of beating autonomously, the organoid is a breakthrough that researchers say could transform cardiac disease research and drug screening. The heart’s ability to beat continuously and rhythmically depends on the sinoatrial node, which is nestled inside the right atrial chamber. Acting as the heart’s “master conductor”,.