The Human Heart: credit iStockphoto via Science Daily
Neurobiologists at Stanford University have created a 'broken heart' that actually floats in a petri dish and beats. The beats are irregular and slow, like the child's whose skin cells were donated to create the heart. The child has Timothy syndrome, a rare genetic disease with irregular heart beat as its most serious characteristic. Children with Timothy syndrome have an average life span of 2.5 years.
The technique of reprogramming human skin cells into embryonic-like cells, called induced pluripotent stem cells (IPS cells), has been used since 2007, and is a far more efficient way to study several disorders because, by adding various chemicals to the IPS cells, they can be made to mimic a variety of disordered cells.
In the Stanford study of Timothy syndrome, the researchers created cells that represent atrial, ventricular and nodal cells. Amazingly, the three cells spontaneously connected to form one chamber, like a human heart. Then, they started beating.
But when the petri dish heart beats, it beats 30 times per minute, not 60 times per minute, as would a healthy heart, because that is the number of beats of the donor's heart, the child who has Timothy syndrome. The petri dish heart also misses beats or suddenly starts racing, like a real life, life-threatening arrhythmia.
Ricardo Dolmetsch, senior author of the study published in the journal Nature, told
the Silicon Valley Mercury News, ""What is wrong in these patients, we
see in these cells." Everything going on in a child's heart can be
viewed in a petri dish without performing surgery on the child to
extract heart cells.
Using special dyes, the Stanford team has been able to identify the source of the problem: the ventricular cells, not the atrial or nodal cells. Then, they tested different drugs on the petri heart, to see how the cells responded. Finally, the team was able to restore a normal heartbeat with roscovitine, a drug being tested for a different ailment. Though the news is positive, the researchers are not yet ready for clinical trials of the drug.
Dolmetsch and his team are also studying IPS cells formed by skin cells from children with Chromosome 16 mutation autism, early-onset schizophrenia, and Velo-Cardio Facial Syndrome.
"Our hope is to advance our basic understanding to the point where we can do a
better job of delivering treatment," he said.
sources: MercuryNews, Genetics Home Reference, Wikipedia