Stem Cell Research News

The problem is that a lung or a brain is not only a bucket of lung/brain cells but it has also a structure.

True wolfram but there are two separate aspects to the approach of first creating the cells, one is to insert them into an existing organ for repair of an already existing structure and there has been some success in that respect as the cells do seem to *self* organize in accord with the organ's wound and the second is to separately either artificially or through a host build an organ from scratch that is transferable to the host.

In the teeth experiments we have seen how simpler but still complex structures like human teeth could be grown on mice. In support of the first approach we have also already seen where eyelet cells are able to repair a pancreas so I think while your criticism is valid it does not represent an insurmountable problem as there does appear to be some form of internal genetic template for self organization at work.

In another hi-tech coup to my alma mater the UW has garnered the contract to preserve and disseminate ESC in the US and to much of the research community around the world by default.

http://edition.cnn.c...k.ap/index.html

The article doesn't emphasize the issue of storing ESC versus ASC but I am still curious why the cryonics comunity doesn't work harder to create a viable market for storing ASC and ESC (umbilicals for example) that could be a competitive lower cost privately controlled tissue banking service generating profits to advance other aspects of their R&D?

Wisconsin group to run stem cell bank
Federal program will store and distribute cells for research

Tuesday, October 4, 2005 Posted: 1439 GMT (2239 HKT)

MADISON, Wisconsin (AP) -- A Wisconsin-based research group will run the nation's first embryonic stem cell bank under a four-year, $16 million federal contract, officials announced Monday.

The WiCell Research Institute, a nonprofit set up in 1999 to support stem cell research at the University of Wisconsin, will store and distribute the cells under a federal plan to reduce their cost.

"At a minimum, we will be a single portal so people can do one-stop shopping" for stem cells, said Carl Gulbrandsen, president of WiCell's board of directors.
(excerpt)

21st are doing that. Especially also vitrification of tissue-engineered constructs to distribute them to the clinics. Kind of smart, I think they are the only ones. When everybody starts large scale tissue engineering things, I would like to have some of their stock ;-)

Interesting point on both counts.

I suggest they should go on our stock lists that caliban started if they are not already there. Are they even publicly traded?

A notable discovery: As reported by Longevity Meme a new method inducing of stem cell regeneration has been discovered using cytokines to stimulate endogenous stem cell production. What is very exciting about this discovery is the simplicity and cost-effectiveness of the treatment would make it broadly available very soon. With some tweaking stem cell niche-specific cytokines could be sytemically administered to provide targeted regeneration to the tissue of choice.

Interesting point on both counts.

I suggest they should go on our stock lists that caliban started if they are not already there.  Are they even publicly traded?

This stock list is only viewable for full members, correct?

GERON ANNOUNCES IMPROVED PRODUCTION METHOD FOR HUMAN EMBRYONIC STEM CELL-DERIVED ISLET CELLS

Menlo Park, CA — January 27, 2006

improved method of deriving islet cells that secrete insulin and glucagon and express the appropriate set of genetic markers confirming them to be human islet cells. Moreover, the new production method generates islet-like clusters that contain proliferating precursors, which if isolated, could potentially enable the scalable production of hESC-derived islets. The drawbacks of the cadaver-based approach are limitations of supply and product variation from donor to donor… As we improve our production method for hESC-derived islet cells and demonstrate their utility in animal models of diabetes, we take an important step toward the clinic.
Full story: http://www.geron.com...view.asp?id=737

Where will this lead?

http://www.theglobea...ory/cancer/home

Stem cells core of more cancers
New discoveries that pinpoint bad seeds leading to a major redirection of research

CAROLYN ABRAHAM

From Monday's Globe and Mail

A spate of new discoveries about the basic biology of cancer is pushing researchers toward an astonishing conclusion: For decades, efforts to cure the disease may have targeted the wrong cells.

Current therapies treat all cancer cells the same. They're aimed at shrinking tumours on the basis that the various cells within them all have similar powers to spawn new cancers and spread destruction.

But mounting evidence suggests that cancer's real culprits -- the roots of perhaps every tumour -- are actually a small subset of bad seeds known best to the world as stem cells.

In what can only be seen as an important example of "nature finding a way" there has been an event that deserves much closer scrutiny. A young liver transplant recipient has had a genetic makeover caused by still unknown circumstances though a viral transcription event from a postoperative infection is suspected.

There are many factors involved including her age at the time of the transplant and that her body must have still been producing large quantities of developmental stem cells. Anyway here is a case to study more and discover any subsequent reports. I am confident there will be more. Can someone get the source article from the New England Journal of Medicine?


Girl switches blood type after liver transplant in first known case: doctors

1 hour, 41 minutes ago

SYDNEY (AFP) - An Australian girl spontaneously switched blood groups and adopted her donor's immune system following a liver transplant in the first known case of its type, doctors treating her said Thursday.

Demi-Lee Brennan was aged nine and seriously ill with liver failure when she received the transplant, doctors at a top Sydney children's hospital told AFP.

Nine months later it was discovered that she had changed blood types and her immune system had switched over to that of the donor after stem cells from the new liver migrated to her bone marrow.

She is now a healthy 15-year-old, Michael Stormon, a hepatologist treating her, told AFP. Stormon said he had given several presentations on the case around the world and had heard of none like it.

"It is extremely unusual -- in fact we don't know of any other instance in which this happened," Stormon told AFP from the Children's Hospital.

"In effect she had had a bone marrow transplant. The majority of her immune system had also switched over to that of the donor."

An article on the case was published in Thursday's edition of the leading US medical journal The New England Journal of Medicine.

Doctors who treated Brennan say she is now only under treatment as an outpatient and are interested to know if the case could have other applications in transplant surgery, where rejection of donor organs by the recipient's immune system is a major hurdle.

Stormon said it appeared that Brennan may have been fortunate because a "sequence of serendipitous events", including a post-transplantation infection, may have given the stem cells from her donor's liver the chance to proliferate.

The task now was to establish whether the same sort of outcome could be replicated in other transplant patients, he said.

Could this new treatment for transplant patients be related causally to what the 9 y/o liver transplpant patient experienced?

Doctors report transplant breakthrough

By ALICIA CHANG, AP Science Writer
2 hours, 56 minutes ago

LOS ANGELES - In what's being called a major advance in organ transplants, doctors say they have developed a technique that could free many patients from having to take anti-rejection drugs for the rest of their lives.

The treatment involved weakening the patient's immune system, then giving the recipient bone marrow from the person who donated the organ. In one experiment, four of five kidney recipients were off immune-suppressing medicines up to five years later.

"There's reason to hope these patients will be off drugs for the rest of their lives," said Dr. David Sachs of Massachusetts General Hospital in Boston, who led the research published in Thursday's New England Journal of Medicine.

Since the world's first transplant more than 50 years ago, scientists have searched for ways to trick the body to accept a foreign organ as its own. Immune-suppressing drugs that prevent organ rejection came into wide use in the 1980s. But they raise the risk of cancer, kidney failure and many other problems. And they have unpleasant side effects such as excessive hair growth, bloating and tremors.

Eliminating the need for anti-rejection drugs is "a huge advance," said Dr. Suzanne Ildstad, a University of Louisville immunology specialist who had no role in the work.

"It still needs some fine-tuning so that everyone who gets treated gets the same consistent outcome ... It's not the holy grail of tolerance yet," she cautioned.

The results do not mean that it is safe for current transplant patients to go off their medicines. Doing so could lead to organ rejection and even death, doctors warn. And Sachs said the treatment will not solve the country's organ shortage.

In the 1990s, Sachs showed the treatment could work in a kidney recipient who was a good genetic match. The woman, who had an organ and marrow transplant in 1998, has not needed anti-rejection drugs for a decade.

The new study involved five people who got kidneys from parents or siblings who had slightly different tissue types from the patients. Since many kidney transplants are similarly mismatched, there is hope more people might one day be spared immune-suppressing drugs.

The breakthrough has changed the life of a Los Angeles man who was one of Sachs' patients.

Derek Besenfelder was born with a genetic kidney disease. After a year on dialysis, he decided to enroll in the experiment and received a kidney and marrow transplant from his mother in 2005. He took anti-rejection pills for eight months, but then was weaned from them. He has been drug-free for two years.

"I wanted to be off the drugs as soon as possible. I had this huge bloated face and didn't feel comfortable going out in public," said Besenfelder, 28, who works as a communications director for a Beverly Hills plastic surgeon.

Doctors have experimented with giving marrow before, during or after organ transplants, while also tinkering with patients' immune systems to prime them to accept the new organs.

Sachs' treatment involved weakening each kidney patient's immune system with intravenous drugs several days before the transplant. After the transplant, the patient got an infusion of marrow from the donor to create a new immune system.

The stem cells from the marrow reprogram the body by allowing new immune cells to grow that don't try to attack the donated organ.

The patients took anti-rejection drugs but were weaned several months later.

Four of the five patients developed a hybrid immune system — where recipient and donor cells live together in the body — for a short time. They were able to stop taking anti-rejection drugs and had healthy kidney function two to five years later.

In the one case that failed, the patient had a second kidney transplant and has been on medications since.

Some researchers such as Ildstad believe the "home run" breakthrough will come when more people respond to the treatment and keep the mixed immune system permanently.

Transplant pioneer Dr. Thomas Starzl of the University of Pittsburgh said donor cells appeared to persist in the bodies of the successful transplant recipients even if those cells were not readily detected.

As promising as the treatment is, Sachs said it won't solve the country's organ shortage problem. Nearly 98,000 people are on the waiting list, according to the United Network for Organ Sharing.

The study was funded by the Immune Tolerance Network, an international consortium of federal and advocacy groups. Sachs plans a follow-up study involving 15 to 20 patients at Massachusetts General and other hospitals.

In the same issue of the New England Journal, Stanford University doctors reported successfully inducing tolerance to a donor organ in a man who was born with one kidney.

Larry Kowalski, now 50, received a matching kidney and marrow from his brother in 2005 and was weaned off drugs six months later. He has been off medications for two years.

Unlike the Massachusetts General cases, doctors said Kowalski has maintained an immune system from his own cells and his brother's. The research was funded by the National Heart, Lung and Blood Institute.

___

On the Net:

New England Journal of Medicine: http://www.nejm.org

Truly amazing. It really gives hope that rejuvenation therapies have potential. I bet her age was a key factor though.

Here is another interesting and important discovery.

Scientists find pancreatic stem cells in mice

By Julie Steenhuysen Thu Jan 24, 2:05 PM ET

CHICAGO (Reuters) - After most scientists had given up the search, a Belgian team said on Thursday they found elusive pancreatic stem cells in adult mice, a finding that could lead to treatments for people with type-1 diabetes.

Scientists have long hunted for adult cells with the capacity to make insulin-producing cells known as beta cells, which help regulate the body's blood sugar levels.

If coaxed into reproducing, adult stem cells or progenitor cells could offer a way to replace beta cells lost or destroyed in people with diabetes.

"For many years people believed that progenitor cells existed in the adult pancreas but were not able to trace or isolate them," Harry Heimberg, a diabetes researcher at Vrije Universiteit Brussels and the Beta Cell Biology Consortium, said in an e-mail.

More recent studies found that under normal circumstances, adult progenitor cells had little to do with the process of making beta cells, he said.

"Most people gave up looking because they were so few and so hard to activate," Heimberg, whose study appears in the journal Cell, said in a statement.

Currently, there is no cure for type-1 diabetes except rare pancreatic cell transplants done under what is known as the Edmonton Protocol, involving transplanting pancreatic cells from cadavers into the liver.

But these transplants are fragile and it takes several donors to make one transplant.

Researchers are also looking to stem cell therapies, including embryonic stem cells, as a way to have a more ready supply of cells to transplant.

Heimberg decided to see if they could get the body's own progenitor cells to make beta cells under abnormal circumstances, such as significant injury.

STRESS AND INFLAMMATION

His team clamped off a duct that drains digestive enzymes from the pancreas in laboratory mice. This led to a doubling of beta cells in the pancreas within two weeks.

These animals began to produce more insulin, suggesting the new beta cells were working. Heimberg suspects the cells began to regenerate as part of an inflammatory response.

He said the study suggests that progenitor cells exist in the adult pancreas of mice and they can be induced to make new insulin-producing cells.

Now scientists must look for these same cells in human adults, and find a way to activate them that does not involve injury to the pancreas.

But if they could figure out how to generate large numbers of beta cells this way, they might be used as beta-cell transplants.

"The most important challenge now is to extrapolate our findings to patients with diabetes," he said.

But, he added, "There is a long way to go before we can talk about a potential cure."

Type-1 diabetes affects an estimated 5 to 10 percent of the 20 million Americans with diabetes. Also called juvenile diabetes, it has different causes from the more common type-2 diabetes that is linked with obesity, poor diet and a lack of exercise.

Type-1 diabetes is an autoimmune disease, caused by the mistaken destruction of insulin-producing cells. Most type-1 diabetics must take insulin daily to control their blood sugar levels.

(Editing by Maggie Fox and Cynthia Osterman)

And here is another breakthrough method being developed in the area of tissue regeneration involving Stem Cells.

Kudos to our Finnish members for encouraging their scientists forward while my fellow Americans sink their heads deeper in the sand.

Finnish patient gets new jaw from own stem cells

By Sami Torma
Fri Feb 1, 1:47 PM ET

HELSINKI (Reuters) - Scientists in Finland said they had replaced a 65-year-old patient's upper jaw with a bone transplant cultivated from stem cells isolated from his own fatty tissue and grown inside his abdomen.

Researchers said on Friday the breakthrough opened up new ways to treat severe tissue damage and made the prospect of custom-made living spares parts for humans a step closer to reality. "There have been a couple of similar-sounding procedures before, but these didn't use the patient's own stem cells that were first cultured and expanded in laboratory and differentiated into bone tissue," said Riitta Suuronen of the Regea Institute of Regenerative Medicine, part of the University of Tampere.

She told a news conference the patient was recovering more quickly than he would have if he had received a bone graft from his leg. "From the outside nobody would be able to tell he has been through such a procedure," she said.

She added, the team used no materials from animals -- preventing the risk of transmitting viruses than can be hidden in an animal's DNA, and followed European Union guidelines. Stem cells are the body's master cells and they can be found throughout the blood and tissues. Researchers have recently found that fat contains stem cells which can be directed to form a variety of different tissues.

Using a patient's own stem cells provides a tailor-made transplant that the body should not reject.

Suuronen and her colleagues -- the project was run jointly with the Helsinki University Central Hospital -- isolated stem cells from the patient's fat and grew them for two weeks in a specially formulated nutritious soup that included the patient's own blood serum. In this case they identified and pulled out cells called mesenchymal stem cells -- immature cells than can give rise to bone, muscle or blood vessels.

When they had enough cells to work with, they attached them to a scaffold made out of a calcium phosphate biomaterial and then put it inside the patient's abdomen to grow for nine months. The cells turned into a variety of tissues and even produced blood vessels, the researchers said. The block was later transplanted into the patient's head and connected to the skull bone using screws and microsurgery to connect arteries and veins to the vessels of the neck. The patient's upper jaw had previously been removed due to a benign tumor and he was unable to eat or speak without the use of a removable prosthesis.

Suuronen said her team had submitted a report on the procedure to a medical journal to be reviewed.

(Reporting by Sami Torma, Editing by Maggie Fox and Michael Kahn and Matthew Jones)

UCLA confirms previous research on converting skin cells to stem cells.

UCLA stem cell scientists reprogram human skin cells into embryonic stem cells

UCLA stem cell scientists have reprogrammed human skin cells into cells with the same unlimited properties as embryonic stem cells without using embryos or eggs.

Led by scientists Kathrin Plath and William Lowry, UCLA researchers used genetic alteration to turn back the clock on human skin cells and create cells that are nearly identical to human embryonic stem cells, which have the ability to become every cell type found in the human body. Four regulator genes were used to create the cells, called induced pluripotent stem cells or iPS cells.

The UCLA study confirms the work first reported in late November of researcher Shinya Yamanaka at Kyoto University and James Thompson at the University of Wisconsin. The UCLA research appears Feb. 11, 2008, in an early online edition of the journal Proceedings of the National Academy of the Sciences.

The implications for disease treatment could be significant. Reprogramming adult stem cells into embryonic stem cells could generate a potentially limitless source of immune-compatible cells for tissue engineering and transplantation medicine. A patient’s skin cells, for example, could be reprogrammed into embryonic stem cells. Those embryonic stem cells could then be prodded into becoming various cells types – beta islet cells to treat diabetes, hematopoetic cells to create a new blood supply for a leukemia patient, motor neuron cells to treat Parkinson’s disease.

“Our reprogrammed human skin cells were virtually indistinguishable from human embryonic stem cells,” said Plath, an assistant professor of biological chemistry, a researcher with the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research and lead author of the study. “Our findings are an important step towards manipulating differentiated human cells to generate an unlimited supply of patient specific pluripotent stem cells. We are very excited about the potential implications.”

The UCLA work was completed at about the same time the Yamanaka and Thomson reports were published. Taken together, the studies demonstrate that human iPS cells can be easily created by different laboratories and are likely to mark a milestone in stem cell-based regenerative medicine, Plath said.

These new techniques to develop stem cells could potentially replace a controversial method used to reprogram cells, somatic cell nuclear transfer (SCNT), sometimes referred to as therapeutic cloning. To date, therapeutic cloning has not been successful in humans. However, top stem cell scientists worldwide stress that further research comparing these reprogrammed cells with stem cells derived from embryos, considered the gold standard, is necessary. Additionally, many technical problems, such as the use of viruses to deliver the four genes for reprogramming, need to be overcome to produce safe iPS cells that can be used in the clinic.

“Reprogramming normal human cells into cells with identical properties to those in embryonic stem cells without SCNT may have important therapeutic ramifications and provide us with another valuable method to develop human stem cell lines,” said Lowry, an assistant professor of molecular, cell and developmental biology, a Broad Stem Cell Center researcher and first author of the study. “It is important to remember that our research does not eliminate the need for embryo-based human embryonic stem cell research, but rather provides another avenue of worthwhile investigation.”

Human ESCs developed from 4 cell embryo

The work could have major ramifications for preimplantation genetic diagnosis (PGD), by enabling the biopsy of one cell from a 4-cell stage embryo, allowing the remaining three cells to develop into a blastocyst (five day embryo) which could be transferred into the uterus and develop into a healthy baby. "Currently, PGD is performed at the 8-cell stage, when one or two cells are removed; others have derived stable hESC lines at this stage but with low efficiency. If hESC derivation at the 4-cell stage turns out to be more efficient then at the 8-cell stage, we might consider to change our PGD policy in cases where we perform human leukocyte antigen (HLA) typing," said Dr. Van de Velde.

HLA molecules play an important role in the immune system by ensuring that our bodies recognise their own cells as their own. By being able to select an HLA-identical embryo, the cord blood of the 'saviour siblings' could help cure an older brother or sister suffering from a genetic disease affecting the production and/or function of hematopoietic (blood producing) stem cells. "We could also combine the pregnancy of an HLA-matched healthy baby with the derivation of a personal hESC line that could be used to generate in vitro hematopoietic stem cells as an additional source of hematopietic stem cells," she said.

a stem cell article http://www.news.com....from=public_rss

The latest breakthrough in disease specific stem cell lines

Technology Review: Why are disease-specific cell lines so important?

Doug Melton: If a patient has Parkinson's disease, their dopamine-producing cells are gone. We don't understand anything about what makes those cells go away--the field is kind of stuck because you can't watch the progression of the disease.

Stem cells can make neurons in a dish. Imagine you have iPS cells from a healthy person and from a Parkinson's patient. If you make dopamine neurons from both sets of cells in separate dishes, you can look at what went wrong with the diseased stem cell. The same approach will work with different degenerative diseases, such as diabetes or ALS [amyotrophic lateral sclerosis, a motor-neuron disease].

TR: How long will it take to get insight into these diseases?

DM: For ALS, Kevin Eggan published a paper on mice showing he could see a defect in cell survival in motor neurons [made from cells derived from an animal model of the disease]. He is now looking for that defect in human cells. The next step would be to determine if that defect is the same in all patients.

Stem Cell Therapy Repairs Congenital Heart Defect

How They Did It

The team reproduced prominent features of human malignant heart failure in a series of genetically altered mice. Specifically, the "knockout" of a critical heart-protective protein known as the KATP channel compromised heart contractions and caused ventricular dilation or heart enlargement. The condition, including poor survival, is typical of patients with heritable dilated cardiomyopathy.

Researchers transplanted 200,000 embryonic stem cells into the wall of the left ventricle of the knockout mice. After one month the treatment improved heart performance, synchronized electrical impulses and stopped heart deterioration, ultimately saving the animal's life. Stem cells had grafted into the heart and formed new cardiac tissue. Additionally, the stem cell transplantation restarted cell cycle activity and halved the fibrosis that had been developing after the initial damage. Stem cell therapy also increased stamina and removed fluid buildup in the body, so characteristic in heart failure.

The researchers say their findings show that stem cells can achieve functional repair in non-ischemic (cases other than blood-flow blockages) genetic cardiomyopathy. Further testing is underway.

$2M In Grants Awarded For Stem Cell Research
http://www.northcoun...19/stem_grants/

Edited by cnorwood, 21 September 2008 - 12:33 AM.
Merged Topics and Posts and Added Headlines for ID

S.D. Banker Supports Stem Cell Research, Philanthropist Makes $30 Million Donation To Calif. Research Group
http://www.cbsnews.c...in4455768.shtml

http://www.sdbj.com/...amp;aID2=129525

Edited by cnorwood, 21 September 2008 - 12:31 AM.
added headline

Breakthroughs
http://www.redorbit....l_breakthrough/

http://www.marketwat...e...}&dist=hppr

http://www.marketwat...p...}&dist=hppr

Edited by cnorwood, 21 September 2008 - 12:33 AM.
added headline

Key Advance In Treating Spinal Cord Injuries Found In Manipulating Stem Cells
http://www.scienceda...80918192939.htm

Edited by cnorwood, 21 September 2008 - 12:21 AM.
added headline

Flatworms Help In Study Of Stem Cells And Cancer
http://www.redorbit....lls_and_cancer/

Edited by cnorwood, 21 September 2008 - 12:19 AM.
added headline

http://www.punchng.c...008091814395689

Adult Stem Cells from Teeth Could Heal Stroke Damaged Brains
http://www.lifesiten...p/08091901.html

Muscle Stem Cell Identity Confirmed by Stanford Researchers
http://www.marketwat...c...}&dist=hppr

Edited by cnorwood, 21 September 2008 - 12:22 AM.
added headline

Celprogen Introduces Stem Cells in Syringes for in vivo applications
http://www.marketwat...p...}&dist=hppr

Edited by cnorwood, 21 September 2008 - 12:22 AM.
added headline

Stanford gets $75 million for stem cell center
Demian Bulwa, Chronicle Staff Writer
Monday, October 6, 2008
http://www.sfgate.co.../BA0M13BU4V.DTL




Monday, October 6, 2008
Letters
Remove research ban on embryonic stem cells?
Support proven cures
http://detnews.com/a...ION01/810060323

In what can only be seen as an important example of "nature finding a way" there has been an event that deserves much closer scrutiny. A young liver transplant recipient has had a genetic makeover caused by still unknown circumstances though a viral transcription event from a postoperative infection is suspected.

There are many factors involved including her age at the time of the transplant and that her body must have still been producing large quantities of developmental stem cells. Anyway here is a case to study more and discover any subsequent reports. I am confident there will be more. Can someone get the source article from the New England Journal of Medicine?


Girl switches blood type after liver transplant in first known case: doctors

This phenomenon is actually not that unexpected. Unbeknownst to many, the liver is the resident organ of the HSC (hematopoeitic stem cell) before it moves into the bone marrow. Throughout life there remain a significant population of blood-forming cells in the liver. In mice, we get HSCs from fetal mice by harvesting their livers, and liver transplants are often not rejected for currently unexplored reasons (a graduate student friend of mine is exploring what cell types are inducing the tolerance). It is not an enormous leap, therefore, to have a very young patient (with putative HSCs still in the liver) begin producing RBCs of a different blood type after a liver transplant. I imagine, like fetal liver transplants in mice, that she is a chimera.

At the same time, it is nifty, I just don't think it will develop into anything interesting from a research perspective.

Testes Stem Cells not as pluripotent as ESC but still differentiate better than ASC.
http://www.eurekaler...c-tsc010509.php

Contact: Krista Conger
kristac@stanford.edu
650-725-5371
Stanford University Medical Center
Testes stem cell can change into other body tissues, Stanford/UCSF study shows

STANFORD, Calif. — Scientists at the Stanford University School of Medicine and at UC-San Francisco have succeeded in isolating stem cells from human testes. The cells bear a striking resemblance to embryonic stem cells — they can differentiate into each of the three main types of tissues of the body — but the researchers caution against viewing them as one and the same.

According to the study, the testes stem cells have different patterns of gene expression and regulation and they do not proliferate and differentiate as aggressively as human embryonic stem cells.

The findings, published in the January issue of the journal Stem Cells, are in contrast to those reported in a recent Nature paper, which concluded that the cells were, in fact, as pluripotent as embryonic stem cells. Pluripotent cells can become any cell in the body and form tumors called teratomas when transplanted into mice. (excerpt)