Biological Pacemaker Using Gene Therapy

Researchers recently induced ordinary cardiac muscle fibers into becoming functioning pacemaker cells by injecting a therapeutic gene.

Working with pigs, a common model for human cardiovascular research, researchers first destroyed the natural pacemaker cells in each subject's heart and installed an electronic pacemaker. They then inserted a gene for transcription factor TBX18 into cardiac muscle tissue using an adenovirus.  Using adenovirous vectors for inserting genes is a common strategy in gene therapy.

Within a couple of days, ordinary myocardial fibers had developed the structure and function of pacemaker cells.  In about 5 days, the electronic pacemakers were no longer needed.

However, this biological pacemaking peaked at about 8 days, then eventually disappeared.  This may occur because the virus-infected cells are probably destroyed by the body's immune defenses.  So researchers are thinking that perhaps, at the very least, this could eventually lead to a temporary treatment for certain arrythmias in humans.

What can we use from this in teaching undergraduate A&P?  

• This is an interesting bit of news that helps illustrate the frontiers of human biomedical sciences.
• This story provides a good case to provoke a discussion of the nature of gene therapy.  
• Why did the effect last only 8 or so day?  
• What does this tell us about transcription factor TBX18?  
• What benefit might this treatment have if developed for humans?
• This may add interest to an discussion of the function of the electrical system of the heart in general, and artificial pacemakers in particular.
• The case also provides a scenario in which the body attacks and destroys virus-infected cells.

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Want to know more?

Next Generation: Biological Pacemakers

• R Williams, The Scientist (the-scientist.com) July 16, 2014
• Plain-English article summarizing the discovery.  Includes quotes from the researchers.
• my-ap.us/1ruocYu

Biological pacemaker created by minimally invasive somatic reprogramming in pigs with complete heart block

• Y-F. Hu et al., Science Translational Medicine, 6:245ra94, 2014. DOI:10.1126/scitranslmed.3008681
• Original research report.
• my-ap.us/1nfErcA

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Photo credit: vfdbsn