Posted on 08/05/2005 1:40:01 PM PDT by West Coast Conservative
Routinely discarded as medical waste, placental tissue could feasibly provide an abundant source of cells with the same potential to treat diseases and regenerate tissues as their more controversial counterparts, embryonic stem cells, suggests a University of Pittsburgh study to be published in the journal Stem Cells and available now as an early online publication in Stem Cells Express.
A part of the placenta called the amnion, or the outer membrane of the amniotic sac, is comprised of cells that have strikingly similar characteristics to embryonic stem cells, including the ability to express two key genes that give embryonic stem cells their unique capability for developing into any kind of specialized cell, the researchers report. And according to the results of their studies, these so-called amniotic epithelial cells could in fact be directed to form liver, pancreas, heart and nerve cells under the right laboratory conditions.
"If we could develop efficient methods that would allow amnion-derived cells to differentiate into specific cell types, then placentas would no longer be relegated to the trashcan. Instead, we'd have a useful source of cells for transplantation and regenerative medicine," said senior author Stephen C. Strom, Ph.D., associate professor of pathology at the University of Pittsburgh School of Medicine and a researcher at the university's McGowan Institute for Regenerative Medicine.
According to U.S. census figures, there are more than 4 million live births each year. For each discarded placenta, the researchers calculate there are about 300 million amniotic epithelial cells that potentially could be expanded to between 10 and 60 billion cells relatively easily.
"Provided that research advances to the point that we can demonstrate these cells' true therapeutic benefit, parents could conceivably choose to bank their child's amniotic epithelial cells in the event they may someday be needed, as is sometimes done now with umbilical cord blood," commented Dr. Strom.
The amnion is derived from the embryo and forms as early as eight days after fertilization, when the fate of cells has yet to be determined, and serves to protect the developing fetus. According to the researchers' studies using placentas from full-term pregnancies, amniotic epithelial cells have many of the telltale surface markers that define embryonic stem cells, and also express the Oct-4 and nanog genes that are known to be required for self-renewal and pluripotency - the ability to develop into any type of cell.
Yet the authors are careful to point out that despite their remarkable similarities to embryonic stem cells, amniotic epithelial cells are not stem cells per se, because they can't grow indefinitely. This may be due to the fact that these amnion-derived cells do not express a certain enzyme, called telomerase, that is important for normal DNA and chromosome replication, and by extension, ultimately, cell division.
"Perhaps it's to their advantage that the amnion epithelial cells lack telomerase expression, because telomerase is associated with many cancers and one of the main concerns about stem cell therapies is that transplanted stem cells would replicate in the recipient to form tumors," noted Toshio Miki, M.D., Ph.D., first author of the paper and an instructor in the department of pathology at the School of Medicine.
To help determine if amnion-derived cells that are delivered directly to tissues would cause tumors, the researchers conducted studies in immune system-deficient mice and found no evidence that tumors had developed seven months after the cells were injected into multiple sites.
While amniotic epithelial cells do not share the same capacity for unlimited replication as do embryonic stem cells, they still can double in population size about 20 times over without needing another cell type serving as a feeder cell layer. This is significant, because to replicate, the currently available embryonic stem cell lines require a bed of mouse cells, traces of which can end up in each new generation of stem cells. Amniotic epithelial cells, on the other hand, create their own feeder layer, with some cells choosing to spread out at the bottom of the culture dish thereby giving those cells just above them the best environment for replicating and for retaining their stem cell characteristics.
With the addition of various growth factors, the authors report the amnion-derived cells could differentiate to become liver cells, heart cells, the glial and neuronal cells that make up the nervous system, and pancreatic cells with genetic markers for insulin and glycogen production.
"In this first paper we sought to determine if amniotic epithelial cells have the potential to differentiate into many different cell types rather than focusing on ways for optimizing this potential for a specific cell type. Further studies will be required to better understand if and how they may be useful in a clinical setting," Dr. Strom added.
The researchers say their original motivation was, and still is, to identify cells with the same therapeutic promise as embryonic stem cells. To this end, they began looking at the viability of amnion as a cell source in late 2001, obtaining discarded placentas from full-term births under an Institutional Review Board-approved protocol. In 2002, the University of Pittsburgh licensed the technology to a company now called Stemnion, LLC, and as part of the agreement, and in keeping with university patent policy, Drs. Strom and Miki will receive license proceeds. Both have served as paid consultants and hold equity in Stemnion.
The research was supported by the Alpha-1 Foundation and the National Institute of Diabetes and Digestive and Kidney Diseases, a part of the National Institutes of Health. In addition to Drs. Miki and Strom, other authors are Thomas Lehmann, Ph.D., and Hongbo Cai, M.D., Ph.D., both from the department of pathology, and Donna Stolz, Ph.D., of the department of cell biology and physiology.
shhh...there are political footballs to be kicked - don't let science get in the way...
This ceased to be a scientific fact a couple of decades old and became breaking news....when? (/rhetorical question)
Let's not be looking for any "win win" situations here. Far too capitalistic. Need a zero sum universe to promote the pro-death agenda.
Didn't I read here just yesterday that another company has just made a major practical breakthrough with placental cells?
This ESCR mania has absolutely zilch to do with actual medical science. The people I've heard make the most noise about it know nothing, absolutely nothing about the various directions and advances in real research.
But why would anyone want to use them? They don't help make the case for retaining abortion on demand.
'Cause if you're worried your child will have a medical problem, the best stem cells to use to cure him or her are his or her own, and peripharlly, stem cells from discarded placentas which match your blood group can possibly save you....oh yeah, but the kids from which the stem cells came are still alive, so the lefties just hate that. I hate white elephants as much as the lefties hate having them discovered after they start making money.
Same story, different source. The story yesterday had two sources -- Pittsburgh Post Gazette -- but was was also referred by Catholic News Agency.
All three articles are about a University of Pittsburgh study. So it is the same news.
If it comes from the mothers abdomen then it should be up to the family to sell the placenta to cover medical costs or start a college/education fund for the child.
I am sick of medicine and science expecting me to donate this, donate that. I say bring back selling parts on eBay. That really wasn't such a bad idea.
There are now four different types of Stem Cell that work better than embryonic stem cell:
1. Adult Stem Cell -- stem cells taken from the nose of an adult. No rejection because it is from the donor for the host (one and the same).2. Umbilical Cord Stem Cell -- these stem cells are very adaptable since they function between two bodies -- the mother and unborn child. Thus going from donor to host seems to have less trouble of rejection.
3. Amniotic fluid stem cells -- stem cells found in amniotic fluid from a pregnancy.
4. Placenta stem cells -- probably very similar to amniotic (it is what this article is about).
Paging Dr. Frist, paging Dr. Frist, code blue in your '08 campaign room!
Why am I not surprised that God has given promise to the "what's left"? Rather than let innocents be killed, he leads to promise in the after birth. Once a child has been born, many riches to be found!
Praise God from whom ALL blessings flow!
All stem cells have the potential to cause tumors. It is one of the problems with using them as a treatment. Yet, it may be that cells similar to stem cells, like the ones in this article, provide only a temporary fix, since they are not immortal like real stem cells.
Just wanted to say that when I was a student nurse doing OB rotation, the instructor took us into a room with a freezer, opened it and pointed out all of these frozen placentas in plastic bags. I asked what were they in the freezer for. She said they sold them. SOLD THEM, I said, quite shocked. She said they sold them to cosmetic companies to put in their products, and went on to tell how the best products had placenta in them because it was so good for you. I remember being really freaked out by this at the time, plus it just didn't quite seem right that someone was taking control of YOUR placenta, without your knowledge and doing this.
What you mean is all cells have the potential to cause tumors.
The reason Embryonic Stem Cells cause tumor is that they are the fastest growing cells. The four I listed are very slow growing. That was even part of the Pittsburgh Post-Gazette article -- that the placenta type stem cells have shown to be similar to embryonic stem cells except they do not seem to cause tumors.
Embryonic stem cell are supposed to grow quite rapidly -- the whole process of quicking forming the baby to survive outside the womb.
The key point is the age of the cells -- the placenta (at child birth) are 9 months old. The embryonic stem cells are only a few days old when the unborn must be destroyed to harvest them.
Embryonic Stem Cells have been the only form of stem cell research to have significant problems with tumor developing. I have not heard of any problems with these other four types -- just the Embryonic Stem Cells.
Firstly, the cells described in this article (and in the journal article, which I just finished reading) are not stem cells, nor do the authors claim them to be. They cannot demonstrate long-term self-renewal of these cells, nor can they expand single cell clones of these cells as you can with true stem cells and which you would need to be able to do for most therapeutic applications of these cells. The very reason that they are not tumorigenic is also the same reason that would probably render them useless except for short term or repeated therapies, namely, that they are not self-renewing. The reason you would use stem cells is to repopulate particular cellular compartments, replacing or assisting native defective cells. These cells would allow you to do that in the short term, but they would eventually die out. The explanation for this is given, namely, they do not have active telomerase. Telomerase adds on the ends of the chromosomes at the end of each cell division in stem cells. It is one way in which cells are programmed to have a limited lifespan. With each division, the length of their telomeres shortens, until finally, after a certain number of division, they can no longer properly maintain chromosomal integrity and often undergo apoptosis (commit suicide). Even adult stem cells do not demonstrate telomerase activity as robust as in embryonic stem cells, and are actually about 1/1000 as effective for long term treatmen. In the majority of tumor cells examined, telomerase has been reactivated. This is one reason why stem cells are prone to forming tumors.
A couple of minor corrections: adult stem cells are not taken only from the nose. They are present in most tissue areas, e.g. bone marrow, lungs, colonic epithelium, etc. Anywhere that you have constantly renewing tissues, you'll probably find stem cells. These are different however, in that they are not necessarily totipotent (capable of forming all cells types). They may form only one or a few cell types depending on their origin. Amniotic fluid stem cells are almost certainly from tissues like the fetal lung which are shed into the amniotic fluid. These also may only be able to form a limited number of cell types. Cord blood stem cells represent the "youngest" type of stem cell, meaning they have the proliferative characteristics closest to embryonic stem cells.
While it used to be assumed that all cells have the potential to cause tumors, that is almost certainly not the case. Current evidence is strongly indicative that cancer initiating cells are probably either a stem cell or an early progenitor cell (the next step down from a stem cell in the differentiation hierarchy) specific for that type of cancer.
I stand corrected.
Sorry if I lectured.....it's a complex topic, but being a cancer geneticist, it's one I'm a bit familiar with!
This is great!!! So maybe we don't need to do embryonic stem cell research -- and maybe we don't need phonies like John Edwards, who promised that everyone would rise from their wheelchairs if Kerry-Edwards were elected.
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