The heartbeat is typically run by the sinoatrial node (or SA node), a cluster of ~10,000 SA cells. Once these pacemaker cells die or are damaged by age and disease, they cease to function properly. At this point, surgeons insert a mechanical device, the pacemaker, to replace the function of the SA node.
Pacemakers are problematic. They break, they’re prone to interference (at least in theory) from all sorts of electronic devices, and they need to be recharged. Researchers Nidhi Kapoor, Hee Cheol Cho, and their colleagues suggest an alternative.
Researchers isolated newborn rat cardiac myocytes (muscle cells) and infected them using bicistronic adenoviral vectors expressing transcription factor genes for a number of genes thought to be vital to cardiac cell development. They found surprisingly, that the activation of one gene, Tbx18, can transform ordinary cardiac muscle cells into sinoatrial node pacemaker cells.
In fact, once transformed the induced SA node pacemaker cells (termed iSAN) are indistinguishable from genuine SA node pacemaker cells. Seven guinea pigs (literally) were subject to new induced SA node rodent pacemakers, and 5 developed heartbeats originating from their iSANs.
It’s important to note that researchers avoided embryonic stem cells. On more than once occasion the implantation of embryonic stem cells or embryonic stell cell derived tissue implanted in adults leads to cancer or cancer precursors.
As such, researchers are hopeful:
Myocytes transduced in vivo acquire the cardinal tapering morphology and physiological automaticity of native SAN pacemaker cells. The creation of induced SAN pacemaker (iSAN) cells opens new prospects for bioengineered pacemakers.