They won't work at all as well. They won't provide excuses for abortion.
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