Fly model of repetitive head trauma speeds up time

Behnke and Zheng describe their model as a platform for future studies on repetitive head injury, in which they can unleash all of the genetic tools fruit flies have to Read more

Brain organoid model shows molecular signs of Alzheimer’s before birth

In a model of human fetal brain development, Emory researchers can see perturbations of epigenetic markers in cells derived from people with familial early-onset Alzheimer’s disease, which takes decades to appear. This suggests that in people who inherit mutations linked to early-onset Alzheimer’s, it would be possible to detect molecular changes in their brains before birth. The results were published in the journal Cell Reports. “The beauty of using organoids is that they allow us to Read more

The earliest spot for Alzheimer's blues

How the most common genetic risk factor in AD interacts with the earliest site of neurodegeneration Read more

George Beck

Bone-strengthening particles stimulate autophagy

Neale Weitzmann and George Beck have been publishing a series of papers describing how silica nanoparticles can increase bone mineral density in animals. Their findings could someday form the basis for a treatment for osteoporosis.

In 2012, we posted an article and video on this topic. We wanted to call attention to a few of the team’s recent papers, one of which probes the mechanism for a remarkable phenomenon: how can very fine silica particles stimulate bone formation?

The particles’ properties seem to depend on their size: 50 nanometers wide – smaller than a HIV or influenza vision. In a 2014 ACS Nano paper, Beck, Weitzmann and postdoc Shin-Woo Ha show that the particles interact with particular proteins involved in the process of autophagy, a process of “self digestion” induced by stress.

“These studies suggest that it is not the material per se that stimulates autophagy but rather size or shape,” they write. Read more

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Strengthening bone with silica nanoparticles

Tiny particles of silicon dioxide – essentially, extremely fine sand — can strengthen bones when introduced into animals, researchers at Emory University School of Medicine have discovered.

The particles stimulate the generation of bone-forming cells and inhibit other cells that break down bone. The findings could someday form the basis for an alternative treatment for osteoporosis.

The results were published recently in the journal Nanomedicine.

The paper represents a collaboration between the laboratories of George Beck and Neale Weitzmann, both in the Division of Endocrinology, Metabolism and Lipids. The project started when Jin-Kyu Lee, now at Seoul National University, came to Beck’s lab with silica nanoparticles he had developed that contained fluorescent dyes. This allowed researchers to track the particles within the body and within cells.

In the laboratory, the nanoparticles stimulate the generation of bone-forming osteoblasts and inhibit the maturation of bone-remodeling osteoclasts. Beck says that the particles’ properties seem to depend on their size (50 nanometers wide) and shape, because larger particles don’t have the same effects. The nanoparticles appear to work by being taken up by the cells and then by inhibiting NF-kB, a molecule that controls inflammation.

Silicon is a trace element in the diet of most people. Scientists have known for several years that dietary silicon is linked to strong bones, but how silicon influences bone growth has remained unclear: it could become physically incorporated into bone, or it could provide signals to the cells that make up bone. To be sure, silica nanoparticles may be acting in a way that is different than dietary silicon.

The particles’ ability to stimulate osteoblasts distinguish them from bisphosphonates, the most common drugs now used to treat osteoporosis, Beck says. Bisphosphonates only inhibit bone breakdown and do not stimulate bone formation.

The Emory team has found that injecting silica nanoparticles can increase the bone density of young mice by roughly 15 percent over six weeks, augmenting the increases coming from adolescent growth.

To test the particles’ potential for use with humans, the researchers are examining whether injection is the best way to deliver the nanoparticles, and whether long-term toxicity is an issue. Inhalation of larger particles of silica dust, an occupational hazard for miners and construction workers, can result in the lung disease silicosis. However, silicosis arises because the lungs can’t absorb and remove the larger dust particles. Since cells clearly can take up the nanoparticles (see video), it is possible that they will not induce the body to respond similarly.

Emory has applied for patents on this technology. A presentation by Emory’s Office of Technology Transfer is available here.

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