Genetic Breakthrough Could Make Pacemakers Obsolete 
10/19/2005 5:12:37 PM

Australian scientists said pacemakers could be obsolete within a decade after researchers managed to revive heart tissue withered by cardiac arrests. The Sydney-based Children's Medical Research Institute (CMRI) said the breakthrough involved injecting a virus containing two of the patients' own genes into the scar tissue caused by heart attacks known as fibroblasts. CMRI head of gene therapy Ian Alexander said the process revived electrical pathways in the fibroblasts, allowing the scar tissue to once again "twitch" like normal heart muscle cells in response to the cardiac system's natural electrical pulses. "It means we can take two genes and we can say to these scar tissue cells 'we want you to take on the properties of heart muscle cell that is capable of being excited electrically'," Alexander told AFP. While the gene transfer technology has so far only been used to repair heart cells in the laboratory, Alexander said he hoped trials on animals, and eventually humans, would begin soon. "What we would envisage is you might have a patient with damage to those electrical pathways caused by scarring from a heart attack, an operation or even in childhood with a congenital heart problem -- we could go in and genetically reprogram them to be a useful cell type that restores the function of the heart," he said. Alexander said the technology had the potential to replace pacemakers, which are currently implanted for a variety of cardiac complications including in heart attack victims to pass on the electrical pulses. He said it meant patients could potentially avoid having pacemaker hardware installed in their bodies, avoiding problems with battery life and parts wearing out. It involves injecting two genes contained in a virus into the fibroblasts. The first reprograms the cells to act like muscle cells and the second allows the cells to communicate with each other so they can pass on electrical pulses. Alexander said a single injection had the potential to repair thousands of scarred heart cells. The breakthrough, published in the medical journal Cardiology, was discovered by a CMRI cardiologist Eddy Kizana during his PhD studies. Kizana is now carrying out post-doctoral studies with US experts to develop his discovery.