io9.com, appropriately enough, has the details on a treatment that seems straight out of science fiction – a virus that infects heart cells and turns them into a biological pacemaker:
Researchers Nidhi Kapoor, Hee Cheol Cho, and their colleagues injected a genetically-modified virus carrying the crucial Tbx18 gene into guinea pigs. This caused ordinary heart cells to transform into the SAN cells; once infected, the heart cells became smaller, thin, and tapered, thus acquiring the exact characteristics of the pacemaker cells.
Tbx18 is the gene that’s responsible for pacemaker cell development during the embryonic stage of development. But in this context, the gene directly reprogrammed the pre-existing heart muscle cells (cardiomyocytes) to the SAN cells.
Of the seven guinea pigs treated, five eventually developed heartbeats that were being driven by their new biologically-endowed pacemaker.
Biological pacemakers have been created before, but this is the first time that a single gene was shown to directly convert the heart muscle cells to pacemaker cells. And in fact, the new cells — redubbed iSAN cells (induced SAN cells) — were indistinguishable from native pacemaker cells. Previous attempts resulted in cells that were not true pacemaker cells.
Moreover, by avoiding the use of embryonic stem cells to derive pacemaker cells, the researchers have reduced the risk of cancerous cells emerging.