Calcium dynamics in embryonic-stem-cell derived cardiac myocytes.

体外培养的小鼠胚胎干细胞可分化为心肌细胞。培养的细胞表现为自发搏动。与成人起搏细胞一样，胚胎干细胞来源的细胞表现出波状的自发钙振荡，通过钠钙交换携带全细胞动作电位。与窦房结细胞一样，细胞内环磷酸腺苷的升高也促进了这种振荡。这表明，被设计成cAMP水平较高的细胞可以形成强大的起搏器。我们现在正在着手研究其他方法，从心室细胞创造耦合的钙和膜时钟，使自然的窦房结细胞具有强大的搏动。除了用创造所需信号环境的单个蛋白质进行转基因外，我们还将探索--在老年组织中--通过转基因发育转录因子来重现导致SAN表型的发育程序。

Cardiac myocytes were differentiated in vitro from cultured embryonic stem cells derived from mice. The cultured cells displayed spontaneous beating. Like adult pacemaker cells, the embryonic stem cell derived cells were found to display wave-like spontaneous calcium oscillations which entrain with whole-cell action potentials by means of sodium-calcium exchange. As in sino-atrial node cells, these oscillations were promoted by elevation of intracellular cyclic AMP. This suggests that cells engineered to have constitutively high cAMP levels could form robust pacemakers. We are now embarking on studies of alternative means of creating, from ventricular cells, the coupled calcium and membrane clocks that endow natural sino-atrial node cells with robust beating. In addition to transfection with individual proteins that create the required signalling milieu, we will explore -- in aged tissue - the recapitulation of developmental programs that lead to the SAN phenotype by means of transfection of developmental transcription factors.