Researchers create stem cells to treat heart disease

Feb. 10, 2011, 3:01 a.m.

Stanford researchers at the School of Medicine can now march to the sound of a different beat. In a study published yesterday, associate professor of neurobiology Ricardo Dolmetsch and his team unveiled a technique that, for the first time, allows scientists to convert human skin cells to heart cells and develop treatments for cardiac deficiencies.

Researchers create stem cells to treat heart disease
(SERENITY NGUYEN/The Stanford Daily)

This novel approach, inspired by a similar experiment conducted by Japanese researchers four years ago, involves reprogramming adult skin cells to a stem-cell-like state, known as induced pluripotent stem cells (iPS), so that they can “differentiate” into other types of cells—in this case cardiomyocytes.

The study focused on treating a genetic disease commonly found among autistic children and tested 20 different drugs on cells suffering from irregular heartbeats, or arrhythmia.

Those suffering from Timothy syndrome have overly lengthy heartbeats, a symptom known as long QT. Long QT, which is caused by a deficient calcium channel and occurs in one out of 7,000 people, slows down heart rate by 50 percent. A typical human heart generates 60 beats per minute. Sufferers of Timothy syndrome have an average lifespan of less than three years.

“Timothy syndrome is a life threatening disorder for reasons not understood,” Dolmetsch said. “Part of it was that the heartbeats were too long and were fatal. We wanted to understand all of the underlying reasons.”

Using special dyes, Dolmetsch can now examine the human heart at a molecular level and determine the exact source of Timothy syndrome.

But he hasn’t been the only one trying to find a cure.

“Lots of drugs treat this rare disorder [but] most don’t work very well,” Dolmetsch said.

In fact, when researchers in Dolmetsch’s lab tested some commercial drugs available to long QT patients, they found that one such drug, roscovitine, actually generated long QT symptoms.

He noted that existing drugs have been tested using cells from mice. But the structural differences between the human heart and that of mice are too great to create accurate parallels in medicine. The normal heart rate of a mouse is much higher than a human, clocking in at 500 beats per minute.

“We’re excited that this might be a potential way of identifying new drugs,” said Dolmetsch of the latest research.

“This is just the beginning of a set of studies,” he added. “A whole bunch of papers will follow.”

Dolmetsch and his research team have already begun to recruit patients with other problems, such as velo-cardio-facial syndrome, a disorder involving deficiencies on specific chromosomes, and overlap cardiac arrhythmia, another long QT disease.

“There are many things that you can do with his technology,” Dolmetsch added. “We can revolutionize the way we study [disease] in people.”

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