Amniotic Fluid Yields New Type of Stem Cell
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GWEN IFILL: Researchers at two leading universities are reporting new promise for stem cell research. Stem cells, which scientists believe can produce muscle, bone, fat, and other human blood and tissue, have been discovered in the amniotic fluid and placenta of pregnant women.
The discovery could change the nature of the debate over stem cell research, or at least broaden the scope of that debate. Joining us to describe the findings, reported in the journal Nature Biotechnology, is the study’s lead researcher, Dr. Anthony Atala, director of the Institute for Regenerative Medicine at Wake Forest University.
DR. ANTHONY ATALA, Wake Forest University: Nice to be with you.
GWEN IFILL: So give us a sense, in layperson’s language, exactly what you found here.
DR. ANTHONY ATALA: Basically, we were looking for an alternate source of stem cells, and we found it in the amniotic fluid, which is the fluid that bathes the baby during development while the mother carries the baby in her womb, as well as the placenta, which is a tissue that surrounds both.
Path to discovery
GWEN IFILL: Now, how did you come about -- did you just happen along this or had you been looking for a while to find an alternative source of stem cells?
DR. ANTHONY ATALA: We actually were looking at it seven years ago. And we found the stem cell population seven years ago, but it took us this long to actually prove that we had a true stem cell.
GWEN IFILL: So people are familiar with amniotic fluid, because when women have that amniocentesis test while pregnant, often the liquid that's withdrawn from the woman's belly is what you found these stem cells in, is that correct?
DR. ANTHONY ATALA: That's exactly right. In that fluid, as well as the placenta, which of course is the afterbirth -- so when the baby is born, comes the afterbirth, which is the placenta -- and we found the same stem cell population there, as well.
GWEN IFILL: And how much, would you say, a pint of this fluid -- how much of this fluid contains stem cells, viable stem cells?
DR. ANTHONY ATALA: Actually, the fluid is chockfull of cells, because the embryo is constantly shedding cells. But we were looking for a stem cell population, a cell that we could derive to become other things that would be nimble. And that particular cell makes up about 1 percent of the cells in the fluid and the placenta.
GWEN IFILL: Describe what you mean when you say "a cell that could be nimble."
DR. ANTHONY ATALA: Well, basically, it's a cell that has the ability to become other tissues. And, therefore, we have been able to drive the cell to what we call all three germ layers, which basically means all three major classes of tissues available in the body, from which all cells come from.
GWEN IFILL: And that's bone, muscle, what...
DR. ANTHONY ATALA: Well, that involves, basically, all tissues in the body. But we actually were deriving it to specific tissue types, such as nerves, bone, muscle, cartilage, the cells that line blood vessels, liver, and other tissues like that.
Differences from other stem cells
GWEN IFILL: Now, there's been a discussion or a debate in this country about stem cell research for some time. This is different. This kind of amniotic stem cell that you're talking about is different from, say, adult stem cells how?
DR. ANTHONY ATALA: That's right. It's actually different from both adult and human embryonic stem cells. It has properties of both. It differs from adult stem cells in that they can grow very rapidly, so in that way they act more like human embryonic stem cells. They double in number every 36 hours, just like human embryonic stem cells.
GWEN IFILL: So if there were a continuum, with embryonic stem cells coming from the embryo on one end, and adult stem cells on the other end, this falls somewhere in the middle, in terms of its ability to replicate?
DR. ANTHONY ATALA: It's actually much closer to the human embryonic stem cells. In fact, it has almost identical replicating abilities as the human embryonic stem cell. So it's one of the advantages of the cells, is that you can grow these in very large quantities for therapy.
Future of the stem cells
GWEN IFILL: So you talk about the advantages. What are the advantages? Who would benefit from the use of these cells, if they were to turn out to be as fruitful as they seem? And how would they benefit?
DR. ANTHONY ATALA: Well, I think that patients may benefit from these technologies, but that's still years down the line. These cells are still early in their development. And, like human embryonic stem cells, we are still trying to figure out how to get those cells to therapy; the same will be true for these cells, as well.
GWEN IFILL: So what do you do with these stem cells? You put them in a freezer and hope that one day they're useful?
DR. ANTHONY ATALA: Well, actually, there are two ways to get these cells for use. One of them is to preserve the cells at the time of birth and freeze those cells down, so you can have a natural repository of cells available to that baby throughout their lifetime, in case they need it for a medical condition.
Or an alternate way to do this is to actually bank these cells. And you need approximately 100,000 specimens in a bank to provide about 99 percent of the U.S. population with a perfect genetic match for transplantation.
GWEN IFILL: Once again, some years down the line, in theory, right?
DR. ANTHONY ATALA: That's right. I think, at this point, we are deriving these cells to become nerves, and bone, and cartilage, and muscle, but these are still experimental studies. And it's going to take several years before we can get these to the patient.
GWEN IFILL: What are the potential medical applications, if everything were as you would hope, and these were as useful as they seem? What would be the medical applications?
DR. ANTHONY ATALA: Well, for example, in this study, we describe how these cells can be converted to nerves that can then be injected into areas of brain injury. And they are able to replenish the brain injury site in experimental models.
So the hope for that, of course, would be for patients with Parkinson's, or stroke disease, or spinal cord injuries. But, again, this is still very early in its development.
GWEN IFILL: Has this been tested in living beings yet, like say in mice?
DR. ANTHONY ATALA: This has been tested in mice, so actually nerves have been injected into mice where they replenished the brain-injured area. They have also been injected into mice to replace bone. We have been able to make liver cells that secrete urea, which is an important component of what the liver does.
GWEN IFILL: And there have also been other experiments done -- have been done in sheep, I gather?
DR. ANTHONY ATALA: That's right. So these cells actually have been in the amniotic fluid for many years, and we've known about their presence for many years. The major finding in this study is the fact that we found a stem cell population that is a true stem cell, in terms of their nimble ability to become all tissue types.
GWEN IFILL: So does this end the argument that we've been having all these years about stem cell research?
DR. ANTHONY ATALA: It does not, mainly because it's another stem cell choice. And I think you really can't tell which cell is going to be best for which indication, and all cells have advantages and disadvantages.