Despite long-held beliefs that heart cells never regenerate, researchers working under the lab supervision of Jonas Frisen at Stockholm’s Nobel Medical Research Institute have found evidence that the heart continuously produces new cells. The scientists made the discovery using carbon dating to track DNA molecules within heart cells.
Why was carbon dating used? Dr. Ratan Bhardwaj, who contributed primary inputs for the research, explains that nuclear testing during the Cold War released significant amounts of radioactive C-14 into the atmosphere. The C-14 mixed with carbon dioxide, which in turn, was used by plants in the photosynthesis process. “Humans and animals ate the plants, so the C-14 went into our system,” he says. “Now could this somehow be tracked, we wondered. With that leap of logic, we zeroed in on the DNA molecule which ought to be fixed from the time when the cell was made, barring very negligible amounts of turnover, so if one could carbon date the DNA from a specific set of cells, one could find out how old that cell was. For the first time, we were able to see and show that the heart actually is continuously making and replenishing new heart cells,” says Dr. Bhardwaj, who is now at the University of Toronto.
Cardiomyocytes, the cells responsible for pumping blood, comprise about 20 percent of the total heart tissue, with the remaining cells primarily supporting the cells of the matrix. “Now, as we grow in age and size, this amazing cell has long been known to ‘hypertrophy’, that is, get bigger with function. We were able to show that it grows in number as well,” says Bhardwaj, who calls the finding a “myth breaker and a paradigm shifter in science” and believes that it will open doors to future stem cell therapeutics and regenerative strategies. “It would be great if researchers could understand this mechanism better and possibly devise a pill to boost the regeneration of the organ, especially after a heart attack or chronic heart failure,” he adds.
News Release: Heart cells grow back, finds Indian doctor www.timesofindia.indiatimes.com April 3, 2009
