Skip to comments.Flaw in induced-stem-cell model - Adult cells do not fully convert to embryonic-like state.
Posted on 02/03/2011 3:09:28 PM PST by neverdem
Medical researchers' hopes of replacing politically fraught embryonic stem (ES) cells with stem cells derived from adult tissues have suffered a setback. Induced pluripotent stem (iPS) cells, created by turning back the developmental clock on adult tissues, and ES cells display similar gene-expression patterns, and both can produce any of the various tissues in the human body. But patterns of epigenetic changes alterations that affect gene expression without changing the DNA sequence tell a different story about iPS cells, a team led by Joseph Ecker, a molecular geneticist at the Salk Institute in La Jolla, California, reports online in Nature this week1.
"They are slightly different creatures," says Chad Cowan, a stem-cell biologist at Massachusetts General Hospital in Boston who was not involved in the work. The finding suggests that iPS cells may not be suitable substitutes for ES cells in modelling or treating disease.
Ecker and his colleagues analysed patterns of DNA methylation, a type of epigenetic change, across the genomes of 15 cell lines. These included four human ES cell lines, five iPS cell lines and the tissues from which they came, as well as differentiated cells made from both kinds of stem cells. "If you look with blinders on, they look fairly similar," says Ecker. "But if you zoom in you find different signatures of what an iPS cell is."
The researchers found that rather than being reset to an embryo-like state, methylation patterns near the tips and centres of chromosomes in the iPS cells resembled those in the adult tissues from which the iPS cells had been derived. This could constrain the types of tissues that the cells are capable of forming. "The reprogramming process, although fascinating, is a fundamentally different way of getting to pluripotency than deriving cells from [embryos]," says George Daley...
(Excerpt) Read more at nature.com ...
On the other hand, iPS cells have been useful in treating disease anyway.
Here's a problem for the pro-ES crowd ~ to wit: methylation is "added" as cells develop, and as organisms grow. Without methylation chickens might come well-armed with teeth and scale-like biological armor plating.
Just conjecture but perhaps these adult cells don’t have
to fully convert in order to work?
I only know about C, D ,and AA cells.
They probably don’t have to be perfect to work ~ but by the same token the Embryonic Stem Cells haven’t yet been methylated so they aren’t perfect either ~ and that’s probably why they can’t be brought forward to produce new organs.
Are they serious? After all the clinical data? In a decade or so, these people are going to look like the anti-vaccine folks.
Stem cell ping - I’m starting to think the entire stem cell enterprise, including embryonic, is a very long way from prime time. If you check the links at the end of the Nature News’ article, you’ll find that, besides these epigenetic differences, they’re using lousy culturing techniques, and they’re getting different copy number variations, deletions of tumor suppressor genes and duplications of oncogenic genes. Maybe they should just stick with adult stem cells and study the salamanders more.
It sounds like this should be very easy to test with animals, which raise no such ethical qualms. Why is it that we know 30,000 ways to cure rat cancer (maybe 30 of those have gone one to success in humans) but no way to build a new rat kidney out of either embryonic or reprogrammed adult stem cells? If that is the case, or if not why aren’t we hearing about it?
They need the genetic equivalent of a word processor to do anything sensible.
The Embryonic Stem Cell advocates are beginning to sound more and more like shamen who need just the right weight of “eye of newt” to make the potions work ~ in short, they already sound barbaric.
I think you meant adult stem cells. Check the links at the end of the Nature News article.
Yeah, they're drawing a difference between iPS and Adult Stem Cells, but the rest of the article is focused on discrediting iPS and ASC to favor ESCs as usual.
Not fully converting back to an embyronic state is rather the point of using adult stem cells. If they did, each one would be a clone of the donor, and an individual human being.
Read comment# 6, or chesk the links at the end of the Nature News’ article. IPSCs are very problematic.
haven’t we been reading of actual adult stem cell case successes?
It's mentioned on the thread. Getting the right type can be problematic. Getting them from very early in development has the most potential in terms the different cell types you can get. That assumes the user knows how to guide their differentiation.
It doesn’t matter anyway. It is wrong destroy human life.
Related topic from my email from COG:
“March 29, 2011 - ACTION ALERT
Biotech company using aborted fetal cell lines to test food flavor enhancers
(Largo, FL) Children of God for Life is calling for a public boycott of major food companies partnering with Senomyx, a biotech company that produces artificial flavor enhancers using aborted fetal cell lines to test their products.
In 2010, the pro-life organization wrote to Senomyx CEO Kent Snyder, pointing out that moral options for testing their food additives could and should be used. But when Senomyx ignored their letter, they wrote to the companies Senomyx listed on their website as “collaborators” warning them of public backlash and threatened boycott. Food giants Pepsico, Kraft Foods, Campbell Soup, Solae and Nestlé are the primary targets of the boycott.
Senomyx website states: ?The company’s key flavor programs focus on the discovery and development of savory, sweet and salt flavor ingredients that are intended to allow for the reduction of MSG, sugar and salt in food and beverage products....Using isolated human taste receptors, we created proprietary taste receptor-based assay systems that provide a biochemical or electronic readout when a flavor ingredient interacts with the receptor.?
Their collaborators provide Senomyx research and development funding plus royalties on sales of products using their flavor ingredients.
?What they don?t tell the public is that they are using HEK 293 ? human embryonic kidney cells taken from an electively aborted baby to produce those receptors?, stated Debi Vinnedge, Executive Director for Children of God for Life, a pro-life watch dog group that has monitored the use of aborted fetal material in medical and consumer products for years.
?They could have easily chosen animal, insect, or other morally obtained human cells expressing the G protein for taste receptors?, she added.
In writing to their collaborators, it took three letters before Nestlé finally admitted the truth about their relationship with Senomyx, noting the cell line was ?well established in scientific research”.
Both Pepsico and Campbell Soup also responded.
Shockingly, Pepsico wrote: ?We hope you are reassured to learn that our collaboration with Senomyx is strictly limited to creating lower-calorie, great-tasting beverages for consumers. This will help us achieve our commitment to reduce added sugar per serving by 25% in key brands in key markets over the next decade and ultimately help people live healthier lives.?
Campbell Soup was more sensitive in their response: ?Every effort is made to use the finest ingredients and develop the greatest selection of products, all at a great value. With this in mind, it must be said that the trust we have cultivated and developed over the years with our consumers is not worth compromising to cut costs or increase profit margins.”
While Campbell didn?t state they would change their methods, their response, gave Vinnedge hope.
?If enough people voice their outrage and intent to boycott these consumer products, it may convince Senomyx to change their methods?, she noted. ?Otherwise, we will be buying Coca-Cola, Lipton soups and Hershey products!”
Biotech company using aborted fetal cell lines to test food flavor enhancers >>
they’re part of vaccines too. so we put aborted cells into millions of babies every year...
everyone thought ipsc was going to be the new norm...what they should do is continue to do research on something that works which is ethical, effective and moral: adult stem cells
“what they should do is continue to do research on something that works which is ethical, effective and moral: adult stem cells”
Which tells us this is about abortion. They want to desensitize people about the value of human life.
I have an immunity problem, but won’t get the flu shot, because I don’t know if aborted fetal cell lines are in the vaccine. It gives me the creeps. (Of course, I could check it out, but it’s just easier to not bother with getting vaccines.)
No, I haven’t. I’ll check it out. Thanks.