Embryonic Stem Cells Repair Human Heart? Not Hardly

The lying headline is bad enough but the opening isn't much better from this Health Day News (via Yahoo) story. -- "Experiments in rats show that human embryonic stem cells can repair damaged heart muscle, improve heart function and slow the progression of heart failure." One naturally assumes we're talking about people here, especially given the headline. But the reader who bothers to go on discovers a much different picture. A few relevant excerpts are printed below and I ask you to note especially the statements in bold.

Using stem cells to repair damaged hearts is something that appears promising, but so far it has been fraught with problems. Previous experiments have shown that it is possible to create heart cells from embryonic stem cells. However, most of these cells do not become heart muscle cells, and many don't survive once transplanted into a damaged heart.

"We found a way to increase the survival of these cells," said lead researcher Dr. Charles Murry, director of the Center for Cardiovascular Biology and Regenerative Medicine at the University of Washington, in Seattle. Murry's team created a "survival" cocktail that prevented the cells from dying. The treated cells were then implanted in rats that had had their hearts damaged to simulate a heart attack. "If we prepared our cells in this cocktail and transplanted them, we could get virtually 100 percent of the rats to have human heart muscle grafts in them," Murry said...

The study shows that growing heart muscle in an injured heart is possible, Murry noted. "In patients who had suffered a heart attack, if we were able to re-muscularize their heart with stem cell-derived heart muscle cells, this should prevent them from developing heart failure," he said. "The rub is that the rat is not a person."

Murry thinks that while the finding is promising, it needs to be confirmed in larger animals such as sheep or pigs, because their hearts beat slower. Rat hearts beat 450 times a minute, while the human heart beats about 70 times a minute. "So, there may be problems that were not predicted with the rat model," he acknowledged...

"The other issue is whether these cells will survive over a long time and how efficiently are they grafted in with the neighboring cells," Chien said. "In addition, because rat hearts beat so fast, they are resistant to arrhythmias. When you put this into an animal with a slower heart rate, would there be arrhythmias over the long term?"

"Clinical applications are many years away," Chien said. "But this is an important step."

There may be other flaws in these experiments which will come out in time. This has frequently been the case with other seeming "breakthrough studies" which prove to be more hype than high quality science. But this story is noteworthy for the outright lie represented in the headline; the begrudging acknowledgment it eventually makes about the experiment not being valid for sheep or pigs (let alone human beings); and for the galling attitude shown by Dr. Murry who refers to his rats as "patients" but shows no sensitivity towards the human embryos who are callously destroyed to provide the cells for his experiments.

"The rub is that the rat is not a person," indeed.