Strange Medicine

Advances in the development of biomaterials are changing the treatment of bone fractures.

Researchers in the United States who have been investigating the properties of silkworm and spider silk have found that it could be used to create artificial—and bio-compatible—bone tissue.

Earlier this year, Japanese researchers successfully grew a bioengineered tooth in the mouth of a mouse. A separate study, carried out by Italian researchers, successfully tested a wood-derived bone substitute in sheep. Meanwhile, Brisbane researchers engineered a synthetic biomaterial that encourages the body to build new bone tissue. All of these studies are producing exciting alternatives to the metal and ceramic implants currently used in orthopaedics and orthodontics.

Professor David Kaplan from Tufts University in Massachusetts presented his team’s findings on silk protein at a conference in Brisbane late last year. He explained that by breaking down and re-engineering the silk protein his team had been able to create and control a protein matrix. Special stem cells derived from bone marrow can be dropped into the matrix where they may trigger the formation and growth of healthy bone.

Earlier this year, Japanese researchers were able to “seed” a mouse’s mouth with “bioengineered tooth germ” which, after 37 days of growth, was beginning to show. The adult rodent had grown and could use its new tooth. Subsequent tests found that the hardness of the enamel and dentin of the tooth were equivalent to those of a natural adult tooth.

Italian researchers at the Instituto Di Scienza E Techologia Dei Materiali Ceramici have pioneered a new method of creating artificial bones using the wood from red oak, rattan or sipo trees. The wood is heated until all that remains is pure carbon. This substrate is coated in calcium, creating calcium carbide. Further chemical processes convert the calcium carbide into carbonated hydroxyapatite, which can then be implanted and serves as the artificial bone. Wood is rather spongy and better replicates the properties of actual bone, compared to the ceramic and metal implants currently used (which can actually cause bone breakage). The process is currently being tested in sheep.

Here in Brisbane, researchers are focusing on how to improve bone grafts and the use of synthetic materials in repairing skeletal damage. Dr Cameron Lutton of Queensland University of Technology points out the limitations of traditional methods.

“If the chunk of bone missing is too big it can’t heal, this is the circumstance that people need assistance,” he explained. “There are several products that fill up bone holes with minerals found in bone. It looks like bone, but it isn’t and it can’t be dealt with by the body in the same way.”

But a biomaterial produced by his research team and colleagues at Stryker Australia may just change that. The new material is coated in a special arrangement of polymers that attract the right proteins to fracture sites to encourage healing in the wounded bone. Animal trials are currently underway.

References

• www.abc.net.au/science/articles/2009/02/19/2495828.htm
• www.abc.net.au/science/articles/2008/11/18/2422636.htm?topic
• http://dsc.discovery.com/news/2009/08/10/artificial-bone-02.html