Could Stem Cell Success Mean An End To Heart Transplants?
Posted Dec 09 2011 10:01pm
Posted on | December 7, 2011 |
When Dr. Piero Anversa from New York Medical College and his colleague Dr. Donald Orlic from the National Institutes of Health announced in April 2001 that stem cells from bone marrow injected into the damaged hearts of mice had morphed into cardiac cells, implanted in the damaged tissue, and laid the seeds for regenerative healing, the news was met with great enthusiasm. (1,2,3)
All understood this was a starting point. But the finding supported early beliefs about the promise and challenge of using stem cells – that they might work before we fully understand why; that if you put them in the right place, they will do the rest; and that if they worked in a damaged heart, they would work in other damaged organs as well. By 2005, the scientific community was in full swing trying to answer basic questions and simultaneously save lives.(4)
Now seven years later, a new study published in Lancet by a group of researchers led by Robert Bolli is reporting dramatic success.(5) They began with a group of heart failure patients whose average ventricular output had declined to a mere 30% (Left Ventricular Ejection Fraction – LVEF). They took a small amount of each patients heart tissue, purified stem cells from that tissue, and injected the cardiac stem cells back into the heart. Since they were the patients’ own cells, there was no chance of rejection.
Four months later, the the group of 18 treated patients had an average LVEF of nearly 39%. A control group’s average LVEF was unchanged. By one year, the treated LVEF had hit nearly 43%. When they performed comparative MRI’s on the treated group’s hearts, they found an average decrease in damaged heart tissue of 30%. Bottom line, the heart’s stem cells were repairing these hearts from inside out.(5)
If one were to choose to explore the promise of regenerative medicine, the heart was always a logical starting point. Hearts weakened by chronic or acute loss of blood supply are exceedingly common. The condition, called Congestive Heart Failure, affects some 5 million people in the United States, and there are 400,000 new cases each year. The major contributor to the development of this condition is a heart attack. More than a million Americans suffer heart attacks each year. Out of those who subsequently develop Congestive Heart Failure, half die within 5 years as a result of their severely weakened hearts.(6)
For many years, the commonly held belief was that heart cells did not divide. By 2001, that had been proven false.(1) As Dr. Anversa said, “For years there has been a general belief that the numbers of cells in the heart was established at birth. But how could anyone believe that the heart could contract so many years using the same cells?”(7)
Evidence supports that the body’s initial attempts to address the acute insult can actually extend the area of injury.(8) The work of Drs. Anversa and Orlic suggested that reparative stem cells existed in the spaces between normal heart cells and in bone marrow.1,8 Other scientists remained cautious. Dr. Irving Weissman, stem cell basic scientist at Stanford University, commented in 2005, “These studies are premature and may in fact place a group of sick patients at risk.”(4) He and other bench researchers wanted more answers.
But the clinicians had a different take. Dr. Emerson Perin of the Texas Heart Institute explained, “The basic science guys don’t see patients that are going to die, but I have to look them in the face every day. It’s ludicrous to say we must understand the molecular mechanisms before we can try anything.”(4) Dr. Nabil Dib of the Arizona Heart Institute voiced a common hope for stem cell use in heart disease when he said, “If this proves efficacious, this will replace heart transplants.” (2)
So here we are, entering a new decade, with great new possibilities. Do we have all the answers? No – but that’s not uncommon. Scientific progress is messy, and knowledge rarely proceeds in a straight line. Bolli and his team illustrate the value of persistence, and a stubborn desire to uncover secrets and reveal hope.
For HealthCommentary, I’m Mike Magee
1. Beltrami AP, Urbanek K, Kajstura J, Yan S, Finato N. Evidence that human cardiac myocites divide after myocardial infarction. NEJM. 2001;344:1750-1757.