Umbilical Cord Stem Cells vs. Embryonic Stem Cells
Umbilical Cord Stem Cells vs. Embryonic Stem Cells
Another reader question: “Dear Anne, Some of my associates are clearly opposed to embryonic stem cell research and are promoting umbilical stem cells as an alternative. Could you do a comparison of the two?”
So I poked around and found out that there are two basic disadvantages to umbilical cord stem cells: one is that there are actually very few of them in cord blood, so they are hard to isolate. The other is that they do not grow well in culture compared to embryonic stem cells. While umbilical cord stem cells appear to have the potential to differentiate into nearly as many kinds of cells as hESCs, they are significantly harder to work with.
Another issue with most kinds of stem cell treatments is immune system response. Stem cells from one’s own umbilical cord blood would not produce an immune system response. Great, for people who have banked their blood. But millions of us are too old to have done so. So we would need umbilical cord stem cells from someone else’s blood, which might provoke an immune system response. (The risk is less than with a straight bone marrow donation or organ transplant, but it is still an issue.) With hESC work, the cells that are produced could be a genetic copy of the patient’s own. This scenario assumes that the cells are specially created for the patient as part of a treatment plan. Getting someone else's hESC cells would presumably also create an immune system response. But the point here is that you can create an exact genetic copy with hESCs, which you can't with umbilical cord stem cells.
There are probably situations in which hESC treatment would not be ideal and it would be better to risk an immune system reponse; for example, what is the risk that the cloned stem cells contain the same conditions leading to cancer or a disease as the patient's original cells? hESC treatment might turn out to be appropriate for injury but not cancer, in which case umbilical cord stem cells could be perfect.
Umbilical cord stem cells certainly have great potential. But until their limitations are overcome, hESCs have more therapeutic advantages. Will this be true 10 years from now? Maybe not. The only way we will know is for research in both to continue.
Below are some sources that I consulted for this. I have highlighted the key points myself but otherwise these are copied directly from the web sites. Please go to those web sites for further information or any citation of the information. Thanks.
From the Stem Cell Research Foundation
http://www.stemcellresearchfoundation.org/About/FAQ.htm
Adult stem cells are undifferentiated cells that are found in small numbers in most adult tissues. However, they are also found in children and can be extracted from umbilical cord blood. A more accurate phrase is “somatic stem cells,” although this phrase has yet to be generally adopted. The primary roles of adult stem cells in the body are to maintain and repair the tissues in which they are found. They are usually thought of as multipotent cells, giving rise to a closely related family of cells within the tissue. An example is hematopoietic stem cells, which form all the various cells in the blood. Recent evidence, however, indicates that some adult stem cell types may be pluripotent, or at least able to differentiate into multiple cell types. For example, hematopoietic stem cells can differentiate into neurons, glia, skeletal muscle cells, heart muscle cells, and liver cells. Whether they actually do this ordinarily within the body is unknown. Blood from the placenta and umbilical cord that are left over after birth is a rich source of hematopoietic stem cells. These so-called umbilical cord stem cells have been shown to be able to differentiate into bone cells and neurons, as well as the cells lining the inside of blood vessels. A potential advantage of using adult stem cells from a patient is that the patient’s own cells could be expanded in culture, treated to differentiate into the desired cells, and then reintroduced into the patient. The use of the patient’s own cells would eliminate any possibility that they might be rejected by the immune system. Disadvantages of using adult stem cells are that they are rare in mature tissues and it is more difficult to expand their numbers in cell culture, compared with ESCs.
From the National Institute of Health
http://stemcells.nih.gov/info/faqs.asp
Why not use adult stem cells instead of using human embryonic stem cells in research?
Human embryonic stem cells are thought to have much greater developmental potential than adult stem cells. This means that embryonic stem cells may be pluripotent—that is, able to give rise to cells found in all tissues of the embryo except for germ cells rather than being merely multipotent—restricted to specific subpopulations of cell types, as adult stem cells are thought to be.
From the International Society for Stem Cell Research
http://www.isscr.org/public/adultstemcells.htm
Umbilical cord blood stem cells can be obtained from the umbilical cord immediately after birth. Like bone marrow, umbilical cord blood is another rich source of hematopoietic stem cells. These hematopoietic stem cells are usually referred to as neonatal stem cells and are less mature than those stem cells found in the bone marrow of adults or children.
The advantages of using cord blood as a source of stem cells are its non-invasive procurement and its vast abundance; thousands of babies are born each day. Until recently, umbilical cord blood was discarded after birth, along with the placenta. Now, in several countries around the world, cord blood is collected and either banked in public banks for general use, or stored by private companies for private use, in private cord blood banks.
Cord blood has recently emerged as an alternative source of hematopoietic stem cells for treatment of leukemia and other blood disorders. In these applications, umbilical cord blood has the notable advantage that despite its high content of immune cells, it does not produce strong graft-versus-host disease, a condition where the graft immune cells attack the patient's body cells. Therefore, cord blood grafts do not need to be as rigorously matched to a recipient as bone marrow grafts.
This expands the available donor pool for hematopoietic stem cell transplants considerably. However, a disadvantage of umbilical cord blood, and an argument against generalized use, is the limited number of stem cells in any given cord. This increases the risk of graft failure once transplanted into an adult.
The use of umbilical cord blood stem cells for other uses, such as organ and tissue repair, is under investigation. However, the stem cells themselves would be recognized as foreign and rejected the same way as a transplanted organ, unless the patient's immune system is strongly suppressed, or has been ablated before transplantation, such as is the case prior to bone marrow transplantations.
Also from the ISSCR:
8. What is unique about stem cells from baby teeth or umbilical cords? Stem cells from umbilical cord blood or the pulp under baby teeth are "younger" stem cells than those obtained from adults. They are able to divide for longer times in cell cultures than most adult stem cells, and may give rise to different tissues. Their potential to form many different cell types is currently being explored.
Umbilical cord blood stem cells are used for stem cell transplantation to reconstitute blood cell formation (the hematopoietic system) in patients that have been irradiated or treated with specific drugs for cancer or leukemia. Also, in some genetic diseases, where patients have a problem forming normal blood cells, a transplantation of matched umbilical cord blood cells can give them a new blood-forming system.
The new cells are infused into the vein of the patient and then they are able to find their way into the bone marrow, in a process called "stem cell homing."
And here is an article discussing the issue:
The Science Correspondent for the on-line magazine Reason wrote about umbilical cord stem cells a year ago. He wrote, “For example, one current problem with stem cells from umbilical cord blood is that they do not continually renew in culture without differentiating like human embryonic stem cells do.” His conclusion was one that I have also come to as I have read about stem cell cells, and in fact is very similar to the point I made above and in a previous post (Americans Support Stem Cell Research, 10/24/05):
However, only more research will tell whether the promise of adult umbilical cord and embryonic stem cells will be fulfilled. Various lines of research should be pursued simultaneously to insure the best chance of discovering effective future treatments. It may well turn out that adult stem cells are good treatments for certain diseases, umbilical ord stem cells work best for others, and embryonic stem cells are better at curing still different maladies. Contrary to the claims of ioconservatives, it is not either adult and umbilical cord stem cells or embryonic ones; for the sake of millions of suffering patients, it's necessary to forge ahead on all three fronts.Here is the link to his full article:
http://www.reason.com/rb/rb120104.shtml
9 Comments:
You might not have done quite enough poking around. Those articles and resources have been mostly outdated since 1968, which is to say 2 years younger than myself. ACSs have are treating more afflictions every month.
http://www.fumento.com/sustemcell.html
Well, let's not confuse things here. One of those articles was published a year ago, and the web site sources are all frequently updated. While stem cell research in animals has been around since the 1960's, human embryonic stem cells were not isolated until 1998, by University of Wisconsin scientist James Madison. Hematapoetic stem cells have been used in leukemia treatment for years in the form of bone marrow transplants, but umbilical cord stem cell research is still fairly new. For example, in 1989, a study was still being done to evaluate the possibility of using umbilical cord blood cells as a source of transplantable stem cells. See
| May 15, 1989 | vol. 86 | no. 10 | 3828-3832
Copyright © 1989 by the National Academy of Sciences
"Human Umbilical Cord Blood as a Potential Source of Transplantable Hematopoietic Stem/Progenitor Cells."
Hal E. Broxmeyer, Gordon W. Douglas, Giao Hangoc, Scott Cooper, Judith Bard, Denis English, Margaret Arny, Lewis Thomas, and Edward A. Boyse
The purpose of this study was to evaluate human umbilical cord blood as an alternative to bone marrow in the provision of transplantable stem/progenitor cells for hematopoietic reconstitution."
Scientists don't put their time and creativity and curiosity into unnecessary research. There is too much to do as it is. If hESCs had no potential, or if ASCs had shown that they could do all the same things, scientists would not be working so hard on hESC research as they are. As I said in the original post, we might get to a point where umbilical cord or adult stem cells can do everything embryonic stem cells can--but we aren't there yet.
General info on stem cells can also be found on wikipedia: http://en.wikipedia.org/wiki/Stem_cell.
I am presently looking for a good history/timeline of stem cell research.
Wakefield, the source you site is Michael Fumento's website. Fumento is known (by his own description) as a right wing conservative and has made a career of arguing against various scientific claims. While I have not read his work and so will not dismiss it out of hand, I do think that if you want to make a scientific argument you need to avoid sources that a)are obviously slanted ideologically and b)are not based directly in personal research. There are liberals opposed to stem cell research and conservatives who support it, it's not a clear-cut ideological position. Try to find more neutral sources. Good researchers are debating the issue, it shouldn't be hard to find a respected bioethicist or researcher from a "liberal" institution who can make an argument against hESCs. It's a complicated issue. But scientifically, umbilical cord stem cells are still harder to use then hESCS.
Anne
OOPS! That's "than" hESCS...And the scientist who isolated hESCS is James Thompson, not James Madison. (U-W is located in Madison.) I can't type this morning.
Anne,
That is some really odd reasoning, to be sure. Either the science behind any issues has its own legs to stand on--or not. It really is that simple.
Yes, ideology is important. But so far the much heralded "neutrality" issue has not paved many successful roads. The reason is that the media have not themselves remained neutral nor intend to. Most journalists are catty or lazy and just defer to those who have the media spotlight. Obviously the advocacy of ESCs needs more of a counterbalance than "neutrality" if the truth is to emerge. Rather than those begging like doggies at the table of Federal funding. AS with art and education, those areas needed Federal transfusions of cash rather than convincing private money beg the question as to their efficacy. That's the first red warning signal that ESCs might be scams.
This kind of "ideological" accusation has been leveled against Fumento before. And it never seems to matter. Notice the response of one person who nonetheless never proved Fumento wrong but thought it would good to get in the "contrarian" dig just the same:
You can't be taken seriously if you don't toe the MSM line
By Michael Fumento
After the Volokh Conspiracy posted my Weekly Standard avian flu piece, one commenter remarked: "Fumento is smart, but he's a contrarian by profession and I think that might affect his objectivity." Yes, I was indeed contrarian when we were told "Now No One Is Safe from AIDS," that Ebola posed a pandemic threat, that SARS could overrun the U.S. hospital system (it killed no Americans), that the avian flu hysteria of 1997-98 was just that, and on countless other issues as recent as Herceptin being portrayed as a "cure" for breast cancer when the very studies cited showed women dying while on the drug. If that doesn't detract from a person's credibility, what should?
Hmmm--a "contrarian"---A CONTRARIAN who nevertheless seems to get it right in the long run against all the blabber and conspiracy about global warming, the (now admitted) myth (mostly) of heterosexual AIDS, apocryphal church burnings in the South, the Atkins diet turning out fatties, and the list goes on...
Left wing blogger Chris Mooney did the same thing on the absurd thinking that if someone is known as a conservative on other issues therefore by some mysterious default mechanism, you can use the label alone as some kind of conspiratorial mindset and leave all else aside. As with the unproven attack on Fumento shown above where Fumento turned out to be correct (the Avian Flu is not about to swamp us), the real issue is not someone's ideological "connection" or even an agenda. The issue is whether or not the other side has made their case. No one who has faced Fumento has won yet. And the reason is simple. Unlike many journalists, the issue is not ideology but whether he does his journalistic "legwork" and goes beyond those with money invested in ESCs, etc. He also does the research on what has come about. Thus far, very little to write home about regarding ESCs.
Lastly, although Fumento has touched on some of the reasons behind the ESC controversy (but citing LIBERALS to do it!!!), his main intent is the alleged science behind ESC--not the other obvious problems. Likewise on Global Warming and other common leftwing scarecrows.
Ideological bias, eh??? Hmm. Funny you mention that as that is what he methodically takes apart.
While he identifies the ideological bias that promote the scare stories, his analysis is based on actual research into the matter. In opposition to almost all other journalistic "exposes."
--WT
Well, we will just have to agree to disagree about hESCs' potential. I consider myself a skeptic and require hard proof about many things too (especially fad diets!), and when I read a media article on stem cells I do my darnedest to go to the research institution that did the study and see what they say directly. Unfortunately it's often just the press release, and the study itself is in a highly technical journal that I don't have a subscription to, so I have to have trust in the referreeing process. (I am not a professional biologist or physician.) I certainly see that there are useful applications for adult stem cells, especially apparently in heart failure treatment, although studies on this have been contradictory. I agree that hESCs still have a long way to go. But I am willing to give them more time and not write them off, especially since it's only 7 years after they were first isolated and only 1 year or so after the first successful SCNT laboratory procedure--no human experiments have been done at all. When multiple double blind clinical trials (ideally in many countries) with hESCS show they are of no use or are harmful to the patients, then I will say it is a scientific dead end. But this hasn't happened yet.
Anne,
I appreciated your valued input and was going to just leave the parting that way, but a few thoughts on one of your comments about potentiality of resarch:
Let no man boast of the Morrow--says the Preacher of Ecclesiastes. OK. Fine.
It's hard to make an ABSOLUTE statement about the potential of ANY research except to see where the money is pulling from. I am not in the game of Absolutes---as far as the material realm. Except maybe for one, regarding relative comfort, if trends continue. And that is that if you have a choice between using your bare fist to pound nails or a hammer, the hammer should get the job. If you have a choice between a 64-bit supercomputer and a 1940s ENIAC punchcard clunker, don't use the clunker to analyze up to the minute stock performance. So it is analogous to hESC vs. hACS. In all the above examples the job will eventually get done regardless of the technique. But some techniques don't wear on flesh or patience as much.
As to the research issue, I think most honest people are suspect about ESCs needing a socialistically enhanced Federal "boost" to play a game of "catch up" with the progress of ASCs. But as with other commodities like TVs, energy, radios, CDs vs. vinyl, the public figures out the best route, not government funding or those who advocate such. There is no reason to think that as earlier entrepreneurs changed the world of industry and science without copying modern day Sweden or Laos in government funding of special projects to get shoes to people, so we should not doubt the market getting lifesaving material to us. We don't go to the People World Revolutionary Computer store or car store to get XP updates and parts for Ford's, do we?
Earlier you wrote that researchers don't spend oodles of time and effort and projects unlikely to get results. But they DO--if big bucks are involved. It happens all the time.
Are ESC then utterly worthless? I would not go that far. After all, it is now revealed that Isaac Newton piddled around with Alchemy and other mystic pseudosciences in addition to the Principia. Only the latter had value to science. I'll admit that in its day both astrology and alchemy had roots in a genuine desire to understand the natural world and today we call these astronomy and physics, respectively.
What I WOULD say is that given the ability to use something that shows all the promise of hESCs without either the headaches or the controversy OR the suspect abilities is worth more to us as a society. A society that casts aside over 2000 years of ethical prowess to play politics over living embryos is suspect in and of itself. Now that ASCs have demonstrated all the abilities of cell differentiation, the excuses are wearing thin for not forging ahead almost exclusively.
Embryonic stem cell propagandists enjoy saying things like "adult stem cell research had a huge head start!" and "embryonic stem cells only need time" (well---and more importantly, massive government funding) to "catch up". As they've only been isolated for 7 years, etc.
But as a new book called The Proteus Effect points out, both types of stem cell research date back 50 years. You might think that one of the chief proponents of hESC research, a Professor of Medicine Jerome Groopman, would know this since his contribution is a review of the book. Research with embryonic stem cells has progressed at a slower pace simply because they are difficult to work with.
It's like trying to rewire your kitchen using gloves and having bulky appliances in the way. Not very economical even if promising later on, when all you had to do was throw the circuit breaker to cook the dinner.
Catherine Verfaillie of the University of Minnesota was the first to discover hASCs that appear to have the potential to become all cell types. Thus the ONE last pitch point for hESC about being "able to differentiate" unlike "all others" is now shot. hASCs can do the same thing for less sweat and tears and money.
Ironically, some of the very diseases he says embryonic stem cells may conquer have long been treated with adult stem cells. Groopman specifically mentions Fanconi's Anemia, but it was first treated with umbilical cord stem cells 16 years ago.
The only possible advantage of embryonic stem cells is always potential. Well shucks--if we as individuals had this kind of everlasting hope we'd never want or worry at all--now would we?
"It's well established that embryonic stem cells can generate any kind of tissue found in the body," Chris Mooney writes flatly. "There is no disagreement among experts about the capacity of (ESCs) to form any and all cells and tissues of the body," Groopman declares. Translation: Disagree with Groopman and you're a hack.
The problem is that hASCs have all the ability to do just the same. This is not theory, conjecture, or guesswork. It is fact. Regardless of Chris Mooney or Ron Reagan's cheapjack political stunt on the grave of his father----a man who'd have asked the same questions I do, like "well little Ronnie, if hESCs are so grand why doesn't the free market pony up the big bucks?"
Hi. Thanks for your thoughts. I don't know if I'll have any time soon to respond in a thoughful way myself, but I appreciate your taking the time to make these points.
Anything that deals with the positive of stem cells, i am behind. it is a great discovery and once all the bugs are sorted out, will be a huge advancement in medical terms.
"Cord blood stem cells have produced promising results when tested in preclinical animal models of nearly every disease that embryonic stem cells have been postulated to help," Cord blood pioneer Dr. Norman Ende.
He and his brother ought to know - they've done it since the 1960s ... and are quite frustrated that cord blood studies get 1/20th the money that human embryonic stem cell research does.
They also get frustrated when (like this article) one presumes cord blood = 'adult' stem cells.
With 100 million births worldwide, it would be easier to match and not have rejection as implied in this article.
AND, we are progressing in being able to expand the stem cells, so that's limited as well.
Some downsides of embryonic that were ignored by this article:
This article also presumes one could get hES from clones - when it's possible we may never be able to clone a human due to meiotoic spindle and protein issues unique to primates ... so that's a real downside.
Also, the biggest hamper to hES research is PATENTS - and why businesses want them so much. Cord blood doesn't have this problem.
Finally, even if you COULD clone, you would be needing EGGS. Women can/do die from egg donations, and women are already being enticed in poor countries w/US$300 to donate. hES = exploitation of poor women of color.
http://www.StemCellCures.Info
http://www.EndEggsploitation.org
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