The Scientist

CIRM weekly stem cell roundup: stomach bacteria & cancer; vitamin C may block leukemia; stem cells bring down a 6’2″ 246lb football player

/ Kevin McCormack / Leave a comment
gastric

This is what your stomach glands looks like from the inside:  Credit: MPI for Infection Biology”

Stomach bacteria crank up stem cell renewal, may be link to gastric cancer (Todd Dubnicoff)

The Centers for Disease Control and Prevention estimate that two-thirds of the world’s population is infected with H. pylori, a type of bacteria that thrives in the harsh acidic conditions of the stomach. Data accumulated over the past few decades shows strong evidence that H. pylori infection increases the risk of stomach cancers. The underlying mechanisms of this link have remained unclear. But research published this week in Nature suggests that the bacteria cause stem cells located in the stomach lining to divide more frequently leading to an increased potential for cancerous growth.

Tumors need to make an initial foothold in a tissue in order to grow and spread. But the cells of our stomach lining are replaced every four days. So, how would H. pylori bacterial infection have time to induce a cancer? The research team – a collaboration between scientists at the Max Planck Institute in Berlin and Stanford University – asked that question and found that the bacteria are also able to penetrate down into the stomach glands and infect stem cells whose job it is to continually replenish the stomach lining.

Further analysis in mice revealed that two groups of stem cells exist in the stomach glands – one slowly dividing and one rapidly dividing population. Both stem cell populations respond similarly to an important signaling protein, called Wnt, that sustains stem cell renewal. But the team also discovered a second key stem cell signaling protein called R-spondin that is released by connective tissue underneath the stomach glands. H. pylori infection of these cells causes an increase in R-spondin which shuts down the slowly dividing stem cell population but cranks up the cell division of the rapidly dividing stem cells. First author, Dr. Michal Sigal, summed up in a press release how these results may point to stem cells as the link between bacterial infection and increased risk of stomach cancer:

“Since H. pylori causes life-long infections, the constant increase in stem cell divisions may be enough to explain the increased risk of carcinogenesis observed.”

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Vitamin C may have anti-blood cancer properties

Vitamin C is known to have a number of health benefits, from preventing scurvy to limiting the buildup of fatty plaque in your arteries. Now a new study says we might soon be able to add another benefit: it may be able to block the progression of leukemia and other blood cancers.

Researchers at the NYU School of Medicine focused their work on an enzyme called TET2. This is found in hematopoietic stem cells (HSCs), the kind of stem cell typically found in bone marrow. The absence of TET2 is known to keep these HSCs in a pre-leukemic state; in effect priming the body to develop leukemia. The researchers showed that high doses of vitamin C can prevent, or even reverse that, by increasing the activity level of TET2.

In the study, in the journal Cell, they showed how they developed mice that could have their levels of TET2 increased or decreased. They then transplanted bone marrow with low levels of TET2 from those mice into healthy, normal mice. The healthy mice started to develop leukemia-like symptoms. However, when the researchers used high doses of vitamin C to restore the activity levels of TET2, they were able to halt the progression of the leukemia.

Now this doesn’t mean you should run out and get as much vitamin C as you can to help protect you against leukemia. In an article in The Scientist, Benjamin Neel, senior author of the study, says while vitamin C does have health benefits,  consuming large doses won’t do you much good:

“They’re unlikely to be a general anti-cancer therapy, and they really should be understood based on the molecular understanding of the many actions vitamin C has in cells.”

However, Neel says these findings do give scientists a new tool to help them target cells before they become leukemic.

Jordan reed

Bad toe forces Jordan Reed to take a knee: Photo courtesy FanRag Sports

Toeing the line: how unapproved stem cell treatment made matters worse for an NFL player  

American football players are tough. They have to be to withstand pounding tackles by 300lb men wearing pads and a helmet. But it wasn’t a crunching hit that took Washington Redskins player Jordan Reed out of the game; all it took to put the 6’2” 246 lb player on the PUP (Physically Unable to Perform) list was a little stem cell injection.

Reed has had a lingering injury problem with the big toe on his left foot. So, during the off-season, he thought he would take care of the issue, and got a stem cell injection in the toe. It didn’t quite work the way he hoped.

In an interview with the Richmond Times Dispatch he said:

“That kind of flared it up a bit on me. Now I’m just letting it calm down before I get out there. I’ve just gotta take my time, let it heal and strengthen up, then get back out there.”

It’s not clear what kind of stem cells Reed got, if they were his own or from a donor. What is clear is that he is just the latest in a long line of athletes who have turned to stem cells to help repair or speed up recovery from an injury. These are treatments that have not been approved by the Food and Drug Administration (FDA) and that have not been tested in a clinical trial to make sure they are both safe and effective.

In Reed’s case the problem seems to be a relatively minor one; his toe is expected to heal and he should be back in action before too long.

Stem cell researcher and avid blogger Dr. Paul Knoepfler wrote he is lucky, others who take a similar approach may not be:

“Fortunately, it sounds like Reed will be fine, but some people have much worse reactions to unproven stem cells than a sore toe, including blindness and tumors. Be careful out there!”

Making brain stem cells act more like salmon than bloodhounds

/ Todd Dubnicoff / Leave a comment

Like salmon swimming against a river current, brain stem cells can travel against their normal migration stream with the help of electrical stimuli, so says CIRM-funded research published this week in Stem Cell Reports. The research, carried out by a team of UC Davis scientists, could one day provide a means for guiding brain stem cells, or neural stem cells (NSCs), to sites of disease or injury in the brain.

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Human neural stem cells (green) guided by electrical stimulation migrated to and colonized the subventricular zone of rats’ brains. This image was taken three weeks after stimulation. Image: Jun-Feng Feng/UC DAVIS, Sacramento and Ren Ji Hospital, Shanghai.

NSCs are a key ingredient in the development of therapies that aim to repair damaged areas of the brain. Given the incredibly intricate structure of nerve connections, targeting these stem cells to their intended location is a big challenge for therapy development. One obstacle is mobility. Although resident NSCs can travel long distances within the brain, the navigation abilities of transplanted NSCs gets disrupted and becomes very limited.

In earlier work, the research team had shown that electrical currents could nudge NSCs to move in a petri dish (watch team lead Dr. Min Zhao describe this earlier work in the 30 second video below) so they wanted to see if this technique was possible within the brains of living rats. By nature, NSCs are more like bloodhounds than salmon, moving from one location to another by sensing an increasing gradient of chemicals within the brain. In this study, the researchers transplanted human NSCs in the middle of such a such gradient, called the rostral migration stream, that normally guides the cells to the olfactory bulb, the area responsible for our sense of smell.

Electrodes were implanted into the brains of the rats and an electrical current flowing in the opposite direction of the rostral migration stream was applied. This stimulus caused the NSCs to march in the direction of the electrical current. Even at three and four weeks after the stimulation, the altered movement of the NSCs continued. And there was indication that the cells were specializing into various types of brain cells, an important observation for any cell therapy meant to replace diseased cells.

The Scientist interviewed Dr. Alan Trounson, of the Hudson Institute of Australia, who was not involved in study, to get his take on the results:

“This is the first study I’ve seen where stimulation is done with electrodes in the brain and has been convincing about changing the natural flow of cells so they move in the opposite direction. The technique has strong possibilities for applications because the team has shown you can move cells, and you could potentially move them into seriously affected brain areas.”

Though it’s an intriguing proof-of-concept, much works remains to show this technique is plausible in the clinic. Toward that goal, the team has plans to repeat the studies in primates using a less invasive method that transmits the electrical signals through the skull.

A call to put the ‘public’ back in publication, and make stem cell research findings available to everyone

/ Kevin McCormack / Leave a comment
Opening the door

Opening the door to scientific knowledge

Thomas Gray probably wasn’t thinking about stem cell research when, in 1750 in his poem “Elegy in a Country Churchyard”, he wrote: “Full many a flower is born to blush unseen”. But a new study says that’s precisely what seems to happen to the findings of many stem cell clinical trials. They take place, but no details of their findings are ever made public. They blush, if they blush at all, unseen.

The study, in the journal Stem Cell Reports, says that only around 45 percent of stem cell clinical trials ever have their results published in peer-reviewed journals. Which means the results of around 55 percent of stem cell clinical trials are never shared with either the public or the scientific community.

Now, this finding apparently is not confined to stem cell research. Previous studies have shown a similar lack of publication of the results of more conventional therapies. Nonetheless, it’s a little disappointing – to say the least – to find out that so much knowledge and potentially valuable data is being lost due to lack of publication.

Definitely not full disclosure

Researchers at the University of Alberta in Canada used the US National Institute of Health’s (NIH) clinicaltrials.gov website as their starting point. They identified 1,052 stem cell clinical trials on the site. Only 393 trials were completed and of these, just 179 (45.4 percent) published their findings in a peer-reviewed journal.

In an interview in The Scientist, Tania Bubela, the lead researcher, says they chose to focus on stem cell clinical trials because of extensive media interest and the high public expectations for the field:

“When you have a field that is accused of over promising in some areas, it is beholden of the researchers in that field to publish the results of their trials so that the public and policy makers can realistically estimate the potential benefits.”

Now, it could be argued that publishing in a peer-reviewed journal is a rather high bar, that many researchers may have submitted articles but were rejected. However, there are other avenues for researchers to publish their findings, such as posting results on the clinicaltrials.gov database. Only 37 teams (3.5 percent) did that.

Why do it?

In the same article in The Scientist, Leigh Turner, a bioethicist at the University of Minnesota, raises the obvious question:

“The study shows a gap between studies that have taken place and actual publication of the data, so a substantial number of trials testing cell-based interventions are not entering the public domain. The underlying question is, what is the ethical and scientific basis to exposing human research subjects to risk if there is not going to be any meaningful contribution to knowledge at the end of the process?”

In short, why do it if you are not going to let anyone know what you did and what you found?

It’s a particularly relevant question when you consider that much of this research was supported with taxpayer dollars from the NIH and other institutions. So, if the public is paying for this research, doesn’t the public have a right to know what was learned?

Right to know

At CIRM we certainly think so. We expect and encourage all the researchers we fund to publish their findings. There are numerous ways and places to do that. For example, we expect each grantee to post a lay summary of their progress which we publish on our website. Stanford’s Dr. Joseph Wu’s progress reports for his work on heart disease shows you what those look like.

We also require researchers conducting clinical trials that we are funding to submit and post their trial results on the clinicaltrials.gov website.

The International Society for Stem Cell Research (ISSCR), agrees and recently updated its Guidelines for Stem Cell Research and Clinical Translation calling on researchers to publish, as fully as possible, their clinical trial results.

That is true regardless of whether or not the clinical trial showed it was both safe and effective, or whether it showed it was unsafe and ineffective. We can learn as much from failure as we can from success. But to do that we need to know what the results are.

Publishing only positive findings skews the scientific literature, and public perception of this work. Ignoring the negative could mean that other scientists waste a lot of time and money trying to do something that has already demonstrated it won’t work.

Publication should be a requirement for all research, particularly publicly funded research. It’s time to put the word “public” back in publication.