Heart Transplants Could Become History With The Use of Adult Stem Cells
By Steve Connor, The New Zealand Herald, November 14, 2006
According to a study on how to repair the effects of cardiac failure, stem cells taken from a patientís own body could help restore the health of a malfunctioning heart.
To replace damaged heart tissue, scientists have shown that it is possible to grow cardiac stem cells in the laboratory prior to transplanting them back into a patient.
Offering an alternative treatment to a complete heart-transplant operation, the findings demonstrate the prospect of rebuilding cardiac muscle that had been destroyed during a heart attack.
Since a pigís heart is so similar to the human heart, the experiment was conducted on pigs. But the researchers involved said that clinical trials on people could begin in 12 months' time.
The technique involves taking a small biopsy - a sample of living heart muscle - that is no bigger than a grain of rice said Professor Eduardo, head of cardiology at the Johns Hopkins University School of Medicine in Baltimore, Maryland.
Using a standard method of accessing the organ through a catheter inserted into an artery in the leg, an infusion of stem cells was put into the animalís heart. The stem cells were derived from a biopsy and then grown in the laboratory prior to infusion.
"This is a relatively simple method of stem cell extraction that can be used in any community-based clinic, and if further studies show the same kind of organ repair that we see in pigs, it could be performed on an outpatient basis," Professor Eduardo said.
"Starting with just a small amount of tissue, we demonstrated that it was possible, very soon after a heart attack, to use the healthy parts of the heart to regenerate some of the damaged parts," he said.
The stem cells in the experiment were labeled with a colored dye so that the scientists could see where they became integrated into the structure of the heart. The cells were cultured for up to a month in the laboratory.
About 10 million cells were injected back into the heart after growing them in the laboratory. The preliminary biopsy extracted about a million stem cells initially. After infusion, the stem cells were still embedded in functioning tissue two months later.
Professor Eduardo said that rather than measuring the physical benefits, the purpose of the experiment was to see whether or not the integration occurred. An examination of the therapeutic qualities of the infusion will form the next stage of the experiment.
"But we have proof of principle, and we are planning to use larger numbers of cells implanted in different sites of the heart to test whether we can restore function as well," Professor Eduardo said.
"If the answer is yes, we could see the first phase of studies in people in later 2007," he said.
As the undifferentiated cells of the body, stem cells are capable of forming specialized tissues, such as cardiac muscle.
Taking adult stem cells from a patient's own heart could provide an alternative to using stem cells taken from a cloned human embryo.
Among other advantages, the transplanted tissue will not be rejected by the body's immune system since the patient will be using his or her own cells. This will eliminate the need for potentially damaging drugs.
"The goal is to repair heart muscle weakened not only by heart attack but by heart failure, perhaps averting the need for heart transplants," said Peter of the Hopkins' Heart Institute.
"By using a patient's own adult stem cell rather than a donor's, there would be not risk of triggering an immune response that could cause rejection," he said.
The results of the study were released yesterday at the American Heart Association's annual meeting in Chicago.