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

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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.

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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!”

From Stem Cells to Stomachs: Scientists Generate 3D, Functioning Human Stomach Tissue

The human stomach can be a delicate organ. For example, even the healthiest stomach can be compromised by H. pylori bacteria—a tiny but ruthless pathogen which has shown to be linked to both peptic ulcer disease and stomach cancer.

The best way to study how an H. pylori infection leads to conditions like cancer would be to recreate that exact environment, right down to the stomach itself, in the lab. But that task has proven far more difficult than originally imagined.

Part of a miniature stomach grown in the lab, stained to reveal various cells found in normal human stomachs [Credit: Kyle McCracken]

Part of a miniature stomach grown in the lab, stained to reveal various cells found in normal human stomachs [Credit: Kyle McCracken]

But now, scientists at the Cincinnati Children’s Hospital Medical Center and the University of Cincinnati College of Medicine have successfully grown functional, human stomach tissue in a dish—the first time such a feat has been accomplished.

Further, they were then able to test how human stomach tissue reacts to an invasion by H. pylori—a huge leap forward toward one day developing treatments for potentially deadly stomach disease.

Reporting in today’s issue of the journal Nature, senior author Jim Wells describes his team’s method of turning human pluripotent stem cells into stomach cells, known as gastric cells. Wells explained the importance of their breakthrough in a news release:

“Until this study, no one had generated gastric cells from human pluripotent stem cells. In addition, we discovered how to promote formation of three-dimensional gastric tissue with complex architecture and cellular composition.”

The team called this stomach tissue gastric organoids, a kind of ‘mini-stomach’ that mimicked the major cellular processes of a normal, functioning human stomach. Developing a human model of stomach development—and stomach disease—has long been a goal among scientists and clinicians, as animal models of the stomach did not accurately reflect what would be happening in a human stomach.

In this study, the research team identified the precise series of steps that can turn stem cells into gastric cells. And then they set these steps in motion.

Over the course of a month, the team coaxed the formation of gastric organoids that measured less than 1/10th of one inch in diameter. But even with this small size, the team could view the cellular processes that drive stomach formation—and discover precisely what happens when that process goes awry.

But what most intrigued the researchers, which also included first author University of Cincinnati’s Kyle McCracken, was how quickly an H. pylori infection impacted the health of the stomach tissue.

“Within 24 hours, the bacteria had triggered biochemical changes in the organ,” said McCracken.

According to McCracken, as the H. pylori infection spread from cell to cell, the researchers also recorded the activation of c-Met, a gene known to be linked to stomach cancer—further elucidating the relationship between H. pylori and this form of stomach disease.

Somewhat surprisingly, little was known about how gastric cells play a role in obesity-related diseases, such as type 2 diabetes. But thanks to Wells, McCracken and the entire Cincinnati Children’s research team—we are that much closer to shedding light on this process.

Wells also credits his team’s reliance on years of preliminary data performed in research labs around the world with helping them reach this landmark:

“This milestone would not have been possible if it hadn’t been for previous studies from many other basic researchers on understanding embryonic organ development.”