The connection between diabetes and frail bones uncovered
Fundamentally, diabetes is defined by abnormally high blood sugar levels. But that one defect over time carries an increased risk for a wide range of severe health problems. For instance, compared to healthy individuals, type 2 diabetics are more prone to poorly healing bone fractures – a condition that can dramatically lower one’s quality of life.
To help these people, researchers are trying to tease out how diabetes impacts bone health. But it’s been a complicated challenge since there are many factors at play. Is it from potential side effects of diabetes drugs? Or is the increased body weight associated with type 2 diabetes leading to decreased bone density? This week a CIRM-funded team at Stanford pinpointed skeletal stem cells, a type of adult stem cell that goes on to make all the building blocks of the bone, as important pieces to this scientific puzzle.
Reporting in Science Translational Medicine, the team, led by Michael Longaker – co-director of Stanford’s Institute for Stem Cell Biology and Regenerative Medicine – found that, compared to healthy animals, type 2 diabetic mice have a reduced number of skeletal stem cells after bone fracture. A study of the local cellular “neighborhood” of these stem cells showed that the diabetic mice also had a reduction in the levels of a protein called hedgehog. Blocking hedgehog activity in healthy mice led to the slow bone healing seen in the diabetic mice. More importantly, boosting hedgehog levels near the site of the fracture in diabetic mice lead to bone healing that was just as good as in the healthy mice.
To see if this result might hold up in humans, the team analyzed hedgehog levels in bone samples retrieved from diabetics and non-diabetics undergoing joint replacement surgeries. Sure enough, hedgehog was depleted in the diabetic bone exactly reflecting the mouse results.
Though more studies will be needed to develop a hedgehog-based treatment in humans, Longaker talked about the exciting big picture implications of this result in a press release:
“We’ve uncovered the reason why some patients with diabetes don’t heal well from fractures, and we’ve come up with a solution that can be locally applied during surgery to repair the break. Diabetes is rampant worldwide, and any improvement in the ability of affected people to heal from fractures could have an enormously positive effect on their quality of life.”
Getting the ethics ahead of the next generation of fertility treatments
The Business Insider ran an article this week with a provocative title, “Now is the time to talk about creating humans from stem cells.” I initially read too much into that title because I thought the article was advocating the need to start the push for the cloning of people. Instead, author Rafi Letzter was driving at the importance for concrete, ethical discussion right now about stem cell technologies for fertility treatments that may not be too far off.
In particular, he alludes to a paper from October (read our blog about it) that reported the creation of female mouse eggs from stem cells. These eggs were fertilized, implanted into the mother and successfully developed into living mice. What’s more, one set of stem cells were derived from mouse skin samples via the induced pluripotent stem cell method. This breakthrough could one day make it possible for an infertile woman to simply go through a small skin biopsy or mouth swab to generate an unlimited number of eggs for in vitro fertilization (IVF). Just imagine how much more efficient, less invasive and less costly this procedure could be compared to current IVF methods that require multiple hormone injections and retrieval of eggs from a woman’s ovaries.
But along with that hope for couples who have trouble conceiving a child comes a whole host of ethical issues. Here, Letzter refers to a perspective letter published on Wednesday in Science Translation Medicine by scientists and ethicists about this looming challenge for researchers and policymakers.
It’s an important read that lays out the current science, the clinical possibilities and regulatory and ethical questions that must be addressed sooner than later. In an interview with Letzter, co-author Eli Adashi, from the Alpert Medical School at Brown University, warned against waiting too long to heed this call to action:
“Let’s start the [ethical] conversation now. Like all conversations it will be time consuming. And depending how well we do it, and we’ve got to do it well, it will be demanding. It will not be wise to have that conversation when you’re seeing a paper in Science or Nature reporting the complete process in a human. That would not be wise on our collective part. We should be as much as possible ready for that.”
Tackling Frontotemporal dementia and Alzheimer’s by hitting the same target.
To develop new disease therapies, you usually need to understand what is going wrong at a cellular level. In some cases, that approach leads to the identification of a specific protein that is either missing or in short supply. But this initial step is just half the battle because it may not be practical to make a drug out of the protein itself. So researchers instead search for other proteins or small molecules that lead to an increase in the level of the protein.
A CIRM-funded project at the Gladstone Institutes has done just that for the protein called progranulin. People lacking one copy of the progranulin gene carry an increased risk for frontotemporal dementia (FTD), a degenerative disease of the brain that is the most common cause of dementia in people under 60 years of age. FTD symptoms are often mistaken for Alzheimer’s. In fact, mutations in progranulin are also associated with Alzheimer’s.
Previous studies have shown that increasing levels of progranulin in animals with diseases that mimic FTP and Alzheimer’s symptoms can reverse symptoms. But little was known how progranulin protein levels were regulated in the cells. Amanda Mason, the lead author on the Journal of Biological Chemistry report, explained in a press release how they tackled this challenge:
“We wanted to know what might regulate the levels of progranulin. Many processes in biology are controlled by adding or removing a small chemical group called phosphate, so we started there.”
These phosphate groups hold a lot of energy in their chemical bonds and can be harnessed to activate or turn off the function of proteins and DNA. The team systematically observed the effects of enzymes that add and remove phosphate groups and zeroed in on one called Ripk1 that leads to increases in progranulin levels. Now the team has set their sights on Ripk1 as another potential target for developing a therapeutic that could be effective against both FTP and Alzheimer’s. Steve Finkbeiner, the team lead, gave a big picture perspective on these promising results:
“This is an exciting finding. Alzheimer’s disease was discovered over 100 years ago, and we have essentially no drugs to treat it. To find a possible new way to treat one disease is wonderful. To find a way that might treat two diseases is amazing.”