Adult and post-natal stem cells are often overlooked in favor of embryonic stem cells in the national debate over the therapeutic use of stem cells. Until now, it has been generally believed that embryonic stem cells had a greater capacity to multiply than post-natal stem cells, making them more desirable to research as a potential treatment, according to Johnny Huard, PhD, director of the Growth and Development Laboratory at Children's Hospital of Pittsburgh.
"Scientists have typically believed that adult or post-natal stem cells grow old and die much sooner than embryonic stem cells, but this study demonstrates that is not the case," said Dr. Huard, senior author of the study. "The entire world is closely following the advances in stem cell research, and everyone is interested in the potential of stem cells to treat everything from diabetes to Parkinson's disease. But there are also many ethical concerns surrounding the use of embryonic stem cells, concerns that you don't have with post-natal or adult stem cells. My belief is that this study should erase doubts scientists may have had about the potential effectiveness of post-natal stem cells."
Researchers from Children's and the University of Pittsburgh in Dr. Huard's laboratory were able to expand post-natal stem cells to a population level comparable to that reached by researchers using embryonic stem cells. Previous research has found that embryonic stem cells could undergo more than 200 population doublings before the cells began to die. A population doubling is a method of measuring the age of a population of cells.
Bridget Deasy, PhD, a scientist in Dr. Huard's laboratory, was first author of the study. Dr. Deasy, a research assistant professor in the Department of Orthopaedic Surgery at the University of Pittsburgh School of Medicine, discovered that a unique population of muscle-derived stem cells was able to undergo more than 200 population doublings, as well. These post-natal cells were able to undergo population doublings while maintaining their ability to regenerate muscle in an animal model, a key finding indicating that they could maintain their treatment potential.
This ability to self-replenish is significant because in order for stem cells to be used for treatment, a large quantity of the cells would be required.
The findings are published in the July 1, 2005, issue of Molecular Biology of the Cell, published by the American Society for Cell Biology. The paper is under consideration for Molecular Biology of Cell paper of the year.
There also may be important advantages to post-natal stem cells when it comes to autoimmunity, according to Dr. Huard, deputy director of the McGowan Institute of Regenerative Medicine and associate professor of Orthopaedic Surgery, Molecular Genetics and Biochemistry, and Bioengineering at the University of Pittsburgh School of Medicine.
The use of embryonic stem cells could be complicated by issues of rejection, with the recipient's immune system rejecting the foreign embryonic stem cells. With post-natal stem cells taken from the recipient and then reintroduced in an autologous manner, rejection would not be an issue.
Dr. Huard is one of the world's top cell biologists researching the potential therapeutic use of stem cells. He currently is working with the stem cells he discovered while searching for a cure for Duchene muscular dystrophy (DMD), a genetic disease that is estimated to affect one in every 3,500 boys. DMD is the most common form of muscular dystrophy affecting children and patients often die in early adulthood because of heart damage.
In addition to searching for a cure for DMD, Dr. Huard's laboratory also is researching the use of stem cells to repair injured muscle following sports-related injuries, as well as to treat cardiac, joint and bone injuries. His work with these stem cells has potential implications ranging from repairing heart muscle damaged by heart attack or disease to the prevention of rejection during organ and tissue transplantation.
The study was supported by the Muscular Dystrophy Association, the National Institutes of Health, the William F. and Jean W. Donaldson Chair at Children's Hospital of Pittsburgh and the Henry J. Mankin Chair at the University of Pittsburgh.
For more information on Dr. Huard's research and Children's, please visit the hospital's Web site at www.chp.edu.