Stem cell stories that caught our eye: Horse patients, Brain cancer stem cells, and a Bony Heart

Horsing around at the World Stem Cell Summit
The World Stem Cell Summit (WSCS) is coming up very shortly (December 6-9) in lovely downtown West Palm Beach, Florida. And this year it has an added attraction; horses.

For my money the WSCS is the most enjoyable of the many conferences held around the US focusing on stem cells. Most conferences have either scientists or patients and patient advocates. This brings them both together creating an event that highlights the science, the people doing it, and the people who hope to benefit from it.

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Eadweard Muybridge’s Galloping Horse
Image: Wikimedia Commons

And this year it’s not just about people, it’s also about horses. For the first time the event will feature the Equine World Stem Cell Summit. This makes sense on so many levels. Animals, large and small, have always been an important element in advancing scientific research, enabling us to test treatments and make sure they are safe before trying them out on people.

But horses are also athletes and sports has always been a powerful force in accelerating research. When you think about the “Sport of Kings” and how much money is involved in breeding and racing horses it’s not surprising that rich owners are always looking for new treatments that can help their thoroughbreds recover from injuries.

And if they help repair damaged bones and tendons in thoroughbreds, who’s to say those techniques and that research couldn’t help the rest of us.

Loss of gene allows cancer stem cells to invade the brain
A fundamental property of stem cells is their ability to self-renew and make unlimited copies of themselves. That ability is great for repairing the body but in the case of cancer stem cells, it is thought to be responsible for the uncontrolled, lethal growth of tumors.

Both stem cells and cancer stem cells rely on special cellular neighborhoods, or “niches”, to support their function. Outside of those niches, the cells don’t survive well. But cancer stem cells somehow overcome this barrier which allows them to spread and do damage to whole organs.

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Brain MRI showing glioblastoma tumor
Image: Wikimedia Commons

A study this week at The University of Texas MD Anderson Cancer Center zeroed in on the gene QK1 that, when deleted in mice, provides cancer stem cells in the brain the ability to thrive outside their niches.  They team also showed that the loss of the gene slowed a cell process called endocytosis, which normally acts to break down and recycle protein receptors on the cell surface. Those receptors are critical for the cancer stem cell’s self-renew function. So by blocking endocytosis, the gene deletion leads to an accumulation of receptors on the cell surface and in turn that boosts the cancer stem cells’ ability to divide and grow outside of its niche.

In a university press release picked up by Science Daily, team lead Jian Hu talked about exploiting this result to find new ways to defeat glioblastoma, the deadliest form of brain cancer:

“This study may lead to cancer therapeutic opportunities by targeting the mechanisms involved in maintaining cancer stem cells. Although loss of QKI allows glioma stem cells to thrive, it also renders certain vulnerabilities to the cancer cells. We hope to design new therapies to target these.”

CIRM-funded scientists uncover mystery of bone growth in the heart
Calcium helps keep our bones strong but a build-up of the mineral in our soft tissues, like the heart, is nothing but bad news for our health. The origins of this abnormal process called ectopic calcification have been a mystery to scientists because the cells responsible for forming bone and secreting calcium, called osteoblasts, are not found in the heart. So where is the calcium coming from?

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Bone-forming osteoblasts. They’re bad news when found in the heart.
Image: Amgen

This week, a CIRM-funded team at UCLA found the answer: cardiac fibroblasts. The researchers suspected that this most abundant cell in the heart was the culprit behind ectopic calcification. So, using some genetic engineering tricks, they were able to track cardiac fibroblasts with a red fluorescent tag inside mice after a heart injury.

Within a week or so after injury, the team observed that cardiac fibroblasts had clustered around the areas of calcium deposits in the heart. It turns out that those cardiac fibroblasts had taken on the properties of heart stem cells and then became bone-forming osteoblasts. To prove this finding, they took some of those cells and transplanted them into healthy mice. Sure enough, the injection sites where the cells were located began to accumulate calcium deposits.

A comparison of gene activity in these abnormal cells versus healthy cells identified a protein called EPPN1 whose levels were really elevated when these calcium deposits occurred. Blocking EPPN1 put a stop to the calcification in the heart. In a university press release, lead author Arjun Deb explained that this detective work may lead to long sought after therapies:

Everyone recognizes that calcification of the heart and blood vessels and kidneys is abnormal, but we haven’t had a single drug that can slow down or reverse calcification; our study points to some therapeutic targets.

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