Adult stem cells multiply reliably,research indicates post-natal cells may work as well as embryonic

Scientists at Children's Hospital of Pittsburgh announced today that they have discovered that adult, or post-natal, stem cells have the same ability as embryonic stem cells to multiply. Calling it a previously unknown characteristic, they said it indicates that post-natal stem cells may play an important therapeutic role.

In a news release, the hospital said "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."

Johnny Huard, director of the Growth and Development Laboratory at Children's Hospital of Pittsburgh, said, "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.

"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."

Researchers from Children's and the University of Pittsburgh said they were able to expand post-natal stem cells to a population level comparable to that reached by researchers using embryonic stem cells.

The findings are published in the July 1 issue of Molecular Biology of the Cell, published by the American Society for Cell Biology.

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Additional info from what looks like the same, less edited article.

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.
[. . .]
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.

Pittsburgh Tribune Review article on the subject:

By Jennifer Bails
TRIBUNE-REVIEW
Friday, June 24, 2005

Children's Hospital of Pittsburgh researchers announced Thursday they have discovered a population of stem cells isolated from mouse muscle with the same ability to multiply as stem cells harvested from human embryos.
Until now, adult, or post-natal, stem cells were believed to be harder to grow than their embryonic counterparts. Many scientists, therefore, assumed they held less promise for curing disease.

A new study being published in the July 1 issue of Molecular Biology of the Cell suggests this might not be the case.

"This is really pushing the boundaries of science," said cell biologist Johnny Huard, director of the Growth and Development Laboratory at Children's Hospital and senior author of the study. "People say post-natal stem cells don't proliferate very well, and we show that is just not true."

Taken from week-old embryos left over from in vitro fertility treatments, embryonic stem cells can morph into cells for virtually all body tissues and organs. They also clone themselves indefinitely, doubling their population more than 250 times without suffering any damage to cell quality.

Adult stem cells are free of the ethical concerns plaguing embryonic stem cells, but researchers thought they would age and die much more rapidly.

Huard and his colleague, Bridget Deasy, decided to test these limits by seeing exactly how long adult stem cells isolated from mouse muscle tissue would survive and multiply in a flask.

They carefully monitored the number of times the cell population doubled, a measure of age. This project took about two years -- and a lot of patience -- to complete, said Huard, who also serves as a professor of orthopedic surgery, molecular genetics and biochemistry at the University of Pittsburgh School of Medicine.

"When we reached 100 population doublings, we said, 'Oh, come on!" he said. "After 200, we thought there would be nothing in the flask and everything would be dead."

Instead, Huard and Deasy showed for the first time that stem cells derived from mouse muscle could undergo more than 200 population doublings -- the same potential for self-renewal as embryonic stem cells.

"One of the criticisms of most adult stem cells is they don't proliferate for a long time," said stem cell expert Dr. Marie Csete from the Emory School of Medicine in Atlanta. "I would guess the vast majority of adult stems cells will not be as robust as these, but (the study) makes for optimism about other populations."

Ample adult stem cells from humans could be grown for use in cell therapy and tissue engineering, making them an attractive alternative to embryonic stem cells, said Huard, who already has shown his muscle-derived stem cells can differentiate into other types of tissue.

Moreover, the older cells cultured by the researchers were just as healthy as the younger ones. Even after multiplying up to 200 times, they discovered the adult stem cells still had the same molecular profile and capacity to regenerate skeletal muscle in mice.

"We've found that we could grow the adult stem cells in large numbers, and they still have the potential to look and act the way they should," said Deasy, who is the study's lead author and a research assistant professor at Pitt.

Unlike stem cells transplanted from embryos, those cultured from a patient's own body don't run the risk of immune rejection. They could be retrieved through a biopsy, multiplied in the lab and then injected back into the patient to heal damaged bones, cartilage or muscles, Huard said.

"For day-to-day clinical practice, maybe we don't even need embryonic stem cells," he said.

Huard and Deasy's study -- paid for in part by the Muscular Dystrophy Association and the National Institutes of Health -- is under consideration for "paper of the year" by the editors of the journal published by the American Society for Cell Biology. It also is being highlighted at this week's International Society for Stem Cell Research meeting in San Francisco, Huard said.

Stem cell researchers are praising Huard's work, but caution that care must be taken before adult stem cells can be used in a clinical setting.

"Before we start putting any adult stem cells in patients, we need to take a long time to show they are going to last and be stable, and that takes a huge effort as Dr. Huard has shown," said Csete, who reviewed the paper for publication.

Huard's next step is to conduct trials with adult stem cells taken from human muscle tissue.

"We have to make sure we don't overstate this entire thing," he said. "We have done this in a mouse, but now we have to do it in people, and that will be more difficult."

http://pittsburghlive.com/x/tribune-review/trib/regional/s_347073.html

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