New pacemaker cells from cardiomycotes

CALIFORNIA – In a paper reported released today from The Cedars-Sinai Heart Institute, Los Angeles, California, USA, researchers detailed a way to restore normal biological functionality to a heart lacking a functional natural pacemaker.

An electronic pacemaker is typically implanted, and serves to generate electrical signals that regulate heart beat

Pacemaker cells are specialised cells that initiate each beat of the heart, and without them (or if they are defective or weak), the heart is unable to maintain an appropriate rhythm. The loss of this functionality has usually been addressed through the insertation of an artificial pacemaker that generates electrical signals and so replaces the role of the defective cells.

The new method, as tested in guinea-pigs, uses a virus able to insert a gene which expresses Tbx18 into cardiomyocytes (general heart muscle cells) to cause them to behave as pacemaker cells. The method caused about 9.2% of transduced cardiomyocytes to start spontaneous firing in the same way that pacemaker cell clusters do in the Sino-Atrial Node. The cells also alter in their shape (morphology) to take up the shape of pacemaker cells. Many cells express their phenotype (functional type) in their shape.

The researchers were able to use this treatment to cure bradycardiac disease in the guinea pig, pointing to the possibility of a similar method being used in humans. The potential benefit of avoiding costly electronic pacemakers of limited life is substantial, however there will need to be a number of years research before this method is likely to be available for clinical trials in humans.

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