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March 4, 2005

Boning Up with Crab Shells. . .
At Engineering Profesor Otto Wilson's BONE/CRAB Lab

By Anne Cassidy

When Otto Wilson looks at a pile of crab shells he doesn’t see the remnants of a seafood dinner but the raw material of human life. Wilson, an assistant professor of biomedical engineering at CUA, is researching the use of pulverized crab shells to repair people’s bones. 

“The part of the crab we use is the part you throw away,” says Wilson. Crab shells are rich in calcium carbonate, which is similar to calcium phosphate, the mineral base of human bones. Wilson’s goal is to use crushed crab shells to repair damaged bone — and perhaps even to stimulate new bone growth — at the cellular and sub-cellular level.

 

Assistant Professor Otto Wilson is invetigating the use of crushed crab shells in bone repair.

Wilson knows from the research of other scientists that nacre (the lining of mollusk shells, also known as mother-of-pearl) can stimulate bone cell growth in human beings. In one study, scientists injected a solution containing powdered nacre into the jaws of women suffering from bone loss in that part of their bodies. The nacre activated bone-forming cells that produced healthy new bone tissue.

“It’s not a big jump from that research to think that crushed crab shells would work, too,” says Wilson, a biomedical engineer with a special interest in biomaterials and hard-tissue engineering. 

There’s a need for new bone replacement materials because the ones most commonly used now — metal and ceramic — have a problem known as stress-shielding. “Bones need stress to heal and grow properly,” Wilson explains. “The problem with metal and ceramic is that they’re stronger than the bone.” They absorb the stress of movement so the load doesn’t transfer to the bone and the bone can atrophy and even die. 

“We need to develop materials that are more closely related to bone in terms of their chemistry, structure and components,” Wilson says.  Bone is both strong and light; furthermore, it’s able to translate the mechanical energy of locomotion into the electrical energy of bone growth and repair. Wilson is looking for a bone-repair material — possibly crab shell — that might replicate those qualities.

This science of abstracting design ideas from nature is called biomimetics. “In biomimetics you look at how God designed things in order to improve technology,” Wilson says. “So we look at the structure and function of bone and crab shells to gain insights on how to make better bone-replacement materials.” 

At this point Wilson’s work is preliminary. “First we’re focusing on the chemistry of the crab shell,” he says. “We have to process the shell to make it useful.”  

In his Pangborn Hall BONE/CRAB Lab (an acronym that stands for Biomimetics, Orthopedics and Nanomaterials Exploration/Composite Research in Advanced Biomaterials), Wilson is crushing the crab shells into a granular powder. From this powder he derives nanoparticles that can be mixed with bone cells. (A nanoparticle has a dimension of less than 100 nanometers, with a nanometer being one-billionth of a meter.)

During a subsequent stage of his research, he will expose bone cells to the crushed crab shells to see how they interact. If the bone cells survive exposure to this alien substance, that’s a good indication that the body wouldn’t reject crab shell, says Wilson.

If the professor proves the compatibility of bone and crushed crab shell, other scientists would need to test the material, as nacre was tested, to see if it stimulates new bone growth. If it does, it could be used in two different ways: It could be put in a paste to repair smaller bone defects. Or, if mixed with certain types of plastic polymers (large molecules formed by chaining simple molecules together), it might be strong enough to support weight, as bones do. This would make it suitable for larger bone implants.

If his basic research turns out to be promising, Wilson believes that crab shells might begin to be used for bone replacement or repair in five years — with CUA research a small but important part of the process. “Most of the work we do here is on developing the materials [rather than testing them on people], but in materials development we’re top-notch,” says the professor, who teaches a CUA class on cell and tissue engineering.

Creating bone replacement material isn’t the only thing Wilson does in his BONE/CRAB Lab. He’s also doing cancer research. 

“We take really small magnetic nanoparticles and put coatings on them which make them appetizing to cancer cells. The cancer cells ingest them. Then we expose the cancer cells to alternating forms of magnetic fields and that causes them to heat up. If you heat the cells up a few degrees you’ll weaken them so they’re more susceptible to chemotherapy. Or you can heat them up 5 to 10 degrees and kill them.” 

On the cancer project Wilson is collaborating with Professor Winston Anderson of Howard University, who says that Wilson’s work in this area “provides a new strategy to enhance our knowledge of cancer cell metastasis.”

 

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