Heart cells share many of the problems of neurons, from a research perspective; they are woefully inept at directing their own growth through space, requiring virtually every effort be made on their behalf, and even when led to the right place require all sorts of special genetic and chemical allowances. It was once thought impossible to regrow neurons, but lately we’ve come to realize that it’s just very, very finicky. Not the least of the reasons for this is conductivity; neurons cannot work unless they somehow come to meet one another such that an electrical signal can propagate between them. Heart cells are much the same — a cluster of so-called pacemaker cells keeps the whole thing contracting as one. This requires not just that the pacemaker signal pass between the cells, but that it happens fast enough for the heart to act seemingly as one coordinated unit.
In pursuit of this, the heart has a class of myocytes that form Purkinje Fibers, long cords that ferry pacemaker signals at a rate unsurpassed in the body. When a contraction signal leaves the pacemaking cells, its order reaches the furthest cells in the heart at an imperceptibly short time after it reaches the closest ones, and so the heart cells seem to beat as one. This ability is absolutely essential to a working heart, and has proven very difficult for organ transplant researchers to overcome.
Enter carbon nanotubes. As anyone familiar with the little critters will know, their important feature is a combination of strength, flexibility, and conductivity. Some combination of these virtues has made them of import to virtually every advanced research and manufacturing sector, from space elevators to flexible computers. Now, we must add conductive tissue development to that quickly growing list. By laying the conductive carbon nanotubes coated with a growth medium, researchers were able to create a scaffold that mimicked the utility of the Purkinje Fibers. By coating the scaffold in rat cardiomyocytes, they were able to create a colony of heart cells capable of contracting properly.