Pacemakers, which are placed in the chest or the abdomen to regulate the contractions of the heart, is used as treatment for individuals with arrhythmia, a condition characterized by the irregular beating of the heart that could lead to shortness of breath, fainting, damage to vital organs and even premature death.
Although pacemakers can be a life saver, use of the device is associated with some discomfort and even risks such as swelling, bleeding and infection of the area where it is placed. Fortunately, biological pacemakers could be available soon.
A group of scientists said that they have identified a way to transform the heart muscle cells of pigs into a biological pacemaker, a development that could possibly lead to the replacement of electronic pacemakers.
The new technique described in the research article published in the Science Translational Medicine on July 15, involves a gene called TBX18, which transforms ordinary heart muscle cells into specialized cells that produce electrical impulses and initiates the beating of the heart.
For their experiment, Eugenio Cingolani, from the Cedars-Sinai Heart Institute in Los Angeles, and colleagues injected the TBX18 gene into a peppercorn-sized area of the pumping chambers of the pigs' heart which prompted the creation of a sino-atrial node, a group of neurons that serves as the natural pacemaker of the heart.
"In essence, we created a new sino-atrial node in a part of the heart that ordinarily spreads the impulse, but does not originate it," study researcher Eduardo Marban, from the Cedars-Sinai Heart Institute explained. Marban said that the newly formed node becomes the functional pacemaker that no longer requires implanted hardware.
Prior to being given the gene therapy, all the animals used in the studies had heart rates that were abnormally low but within two days after the treatment, the pigs that were injected with the gene were found to have stronger heartbeats compared with those that were not given the gene.
From the initial 50 beats per minute prior to treatment, the heart rates of the treated pigs increased to the normal range of 70 to 90 beats per minute and this persisted for 14 days. At the end of the two week period, however, the heart rates of the treated pig started to falter but remained stronger compared with those of the untreated pigs.
Still, the researchers hope that the procedure could be advanced to human trials. "This development heralds a new era of gene therapy where genes are used not only to correct a deficiency disorder, but actually to convert one kind of cell into another type to combat disease," Marban said.
