Stem Cells, regenerative Medicine and the Heart

 

 

 

Stem Cells, Regenerative Medicine and the Heart   

 

The road from basic science to clinical practice can be a rocky one. A perfect case in point is our 

current struggle on both sides of the Atlantic to realize the benefits of utilizing regenerative medicine 

as a treatment for damaged hearts. 

 

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. Now, four years later, the scientific community is in 

full gear trying to answer basic questions and simultaneously save lives. And both the issues and 

emotions involved are complex and deeply personal.4 

 

If one were to choose to explore the promise of regenerative medicine, the heart would be 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 4.8 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.5 

 

For many years, the commonly held belief was that heart cells did not divide. That has now been 

proven false.1 As Dr. Anversa has 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?”6   

 

That said, all agree that normal cell division is not an adequate response in the face of the broad 

and extensive damage that rapidly occurs following an acute blockage of a coronary artery. In fact, 

evidence supports that the body’s initial attempts to address the acute insult can actually extend the 

area of injury.7 

 

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  Others over the past 4 years have been unable to 

confirm their experiments.4  During this same period, clinicians in at least 10 different studies have 

harvested bone marrow and peripheral cells, cultured them to expand their numbers, and injected 

 

them or deposited them into the damaged areas of patients’ hearts, then watched, waited, and 

measured with variable and not fully conclusive results.5 

 

To all of this, Dr. Irving Weissman, stem cell basic scientist at Stanford University, has 

responded, “These studies are premature and may in fact place a group of sick patients at risk.”4 He 

and other bench researchers want more answers. What is the natural role of stem cells in the heart?  

How do heart cells normally repair themselves?  Which cells in the bone marrow are most effective in 

heart repair?  Can peripheral cells work as well as bone marrow cells?  Does the stem cell system 

age and become less effective as you age? Are there homing systems that guide stem cells to the 

damaged areas? 

 

All good questions, of course. Yet the need is urgent and real, and it is concurrently driving 

experimental studies in humans. Dr. Emerson Perin of the Texas Heart Institute explains, “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   

 

While there is certainly disagreement on the pacing and order of studies, there is no 

disagreement on the potential promise of regenerative medicine for treating heart disease. The NIH 

says, “Scientists are interested in exploring this ability to provide replacement tissue for the damaged 

heart. This approach has immense advantages over heart transplant.”4 Certainly, regenerative 

medicine would be less invasive and less expensive. Beyond this, it would resolve a nagging supply 

and demand crisis. As of September 2005, there were more than 85,000 Americans awaiting organ 

transplants. The year before, nearly 7,000 Americans died while awaiting an organ.9  

 

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 Dr. Dib will be 

participating in a roundtable of leading experts put together by the American Federation for Aging 

Research (AFAR), a group that strongly supports stem cell research and wants to help sort out the 

questions it poses. According to Dr. George M. Martin, AFAR’s scientific director, “We want to learn 

more about the relevance of stem cell research in understanding the basic mechanisms of aging and 

its regenerative applications for heart disease, cognitive repair and cell renewal in aged tissue.”10  

 

Making reasonable progress in the face of uncertainty requires data transparency, reliance on 

high quality and ethical research practices, and open communication and dialogue between 

scientists, clinicians and health consumers. There is a role for optimism, as there is for action. 

Progress can be messy and still be progress. As it occurs, the focus sharpens and the questions gain 

clarity. Some of the questions out there now, according to the NIH, include:  How long will 

replacement cells function?  Do rodent findings reflect what will happen in humans?  Can we harvest 

and deliver the cells in time in the face of an acute heart attack?  Could a vulnerable patient donate 

and bank cells ahead of time? 5  

Are we taking two steps forward and one step back?  Perhaps! But it’s progress still the same! 

 

For Health Politics, I’m Mike Magee. 

 

 

References 

 

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. 

2. Reason To Take Heart. CBS News. November 18, 2002. Available at: 

http://www.cbsnews.com/stories/2002/11/18/health/main529683.shtml. 

3. Institute of Science in Society report. Adult Bone Marrow Cells Mend Heart Without Transplant. 

August 24, 2001. Available at: http://www.i-sis.org.uk/Bone_Marrow.php. 

4. Wade N. Tracking the Uncertain Science of Growing Heart Cells. The New York Times. March 

14, 2005.  

5. National Institutes of Health. Stem Cell Information: Can Stem Cells Repair a Damaged Heart? 

Available at: http://stemcells.nih.gov/info/scireport/chapter9.asp. 

6. Touchette N. Stem Cells Found in the Heart. Genome News Network. October 17, 2003. 

7. Institute of Science in Society press release. Patient’s Own Stem Cells Mend Heart. January 

13, 2005. Available at: http://www.i-sis.org.uk/POSCMH.php. 

8. Orlic D, Kajstura J, Chimenti S, Jakoniuk I, Anderson SM. Bone marrow cells regenerate 

infarcted myocardium. Nature. 2001:410:701-705. 

9. The Organ Procurement and Transplantation Network. National Data. Available at: 

http://www.optn.org/data/. 

10. Personal communication with George M. Martin. October 13, 2005.