Tag Archives: bone morphogenetic protein 2

Speeding up bone growth with a tobacco virus

Steven Powell in a June 22, 2012 article for the University of South Carolina news office describes progress that Qian Wang, a chemistry professor, and his colleagues at the University of South Carolina have made toward cutting down the time it takes to heal a bone. From the June 22, 2012 article (Note: I have removed a link),

Wang, Andrew Lee and co-workers just reported in Molecular Pharmaceutics that surfaces coated with bionanoparticles could greatly accelerate the early phases of bone growth. Their coatings, based in part on genetically modified Tobacco mosaic virus, reduced the amount of time it took to convert stem cells into bone nodules – from two weeks to just two days.

Here’s a description of the healing process,

The human body continuously generates and circulates cells that are undifferentiated; that is, they can be converted into the components of a range of tissues, such as skin or muscle or bone, depending on what the body needs.

The conversion of these cells – called stem cells – is set into motion by external cues. In bone healing, the body senses the break at the cellular level and begins converting stem cells into new bone cells at the location of the break, bonding the fracture back into a single unit.

There are reasons for wanting to speed the process,

The process is very slow, which is helpful in allowing a fracture to be properly set, but after that point the wait is at least an inconvenience, and in some cases highly detrimental.

“With a broken femur, a leg, you can be really incapacitated for a long time,” said Wang. “In cases like that, they sometimes inject a protein-based drug, BMP-2, which is very effective in speeding up the healing process. Unfortunately, it’s very expensive and can also have some side effects.”

Wang and his colleagues stumbled across a new approach to speeding up the healing process (Note: I have removed a link),

In a search for alternatives four years ago, Wang and colleagues uncovered some unexpected accelerants of bone growth: plant viruses. They originally meant for these viruses, which are harmless to humans, to work as controls. They coated glass surfaces with uniform coverings of the Turnip yellow mosaic virus and Tobacco mosaic virus, originally intending to use them as starting points for examining other potential variations.

But they were surprised to find that the coatings alone could reduce the amount of time to grow bone nodules from stem cells. Since then, Wang and co-workers have refined their approach to better define just what it is that accelerates bone growth.

This is a description of their latest refinements and what they imagine to be possible at some time in the future,

In the most recent effort spearheaded by Lee, they built up a layer-by-layer assembly underneath the virus coating to ensure stability. They also genetically modified the viral protein to enhance the interaction between the coating and the stem cells and help drive them toward bone growth.

Their efforts were rewarded with bone nodules that formed just two days after the addition of stem cells, compared to two weeks with a standard glass surface. They’re also carefully following the cellular signs involved with success. BMP-2 is involved, but as an intrinsic cellular product rather than an added drug.

“BMP-2 is bone morphogenetic protein 2. It can be added as a protein-based drug, but it’s a natural protein produced in the cell,” said Wang. “We see upregulation of the BMP-2 within 8 hours with the new scaffold.” They also find osteocalcin expression and calcium sequestration, two processes associated with bone formation, to be much more pronounced with their new coatings.

“What we’ve seen could prove very useful, particularly when it comes to external implants in bones,” said Wang. “With those, you have to add a foreign material, and knowing that a coating might increase the bone growth process is clearly beneficial.”

“But more importantly, we feel we’re making progress in a more general sense in bone engineering. We’re really showing the direct correlation between nanotopography and cellular response. If our results can be further developed, in the future you could use titanium to replace the bone, and you might be able to use different kinds of nanoscale patterning on the titanium surface to create all kinds of different cellular responses.” [emphasis mine]

I had not expected to leap from bone tissue engineering to creating titanium bones  the sort of thing that I imagine much interests the military.  As for “different cellular responses,” my imagination fails. What is being suggested? Thanks to the June 25,2012 news item on Nanowerk for alerting me to this work.