Conference report: building a biologic pacemaker.

Although electronic pacemakers are an excellent therapy, their persistent shortcomings (need for monitoring and replacement, indwelling catheter electrodes in the heart, possibility of infection, lack of autonomic responsiveness, geometric limitations with respect to pediatric patients) are sufficient to warrant a search for better alternatives. The biologic pacemaker, which is a tissue that spontaneously or via engineering confers pacemaker properties to regions of the heart, is one such alternative. A variety of approaches have been taken in attempting to produce biologic pacemakers. These can be considered under 3 major headings: (1) the use of viral vectors to deliver genes to regions of the heart such that a pacemaker potential resulting in spontaneous impulse initiation evolves in the region of gene administration; (2) the use of embryonic stem cells grown along a cardiac lineage and manifesting the properties of sinus node cells; (3) the use of mesenchymal stem cells as platforms to carry pacemaker genes to the heart, relying on gap junctional coupling such that the stem cell and a coupled myocyte form a single functional unit to generate pacemaker function.