Synthetic bone glue based on marine worm secretions

Synthetic Sea Worm Glue May Mend Shattered Knee, Face Bones
ScienceDaily (Nov. 26, 2008)
http://www.sciencedaily.com/releases/2008/11/081125085620.htm

Glue bones
Aug 25th 2009
From Economist.com
http://www.economist.com/
displaystory.cfm?story_id=14299348

The discovery of a marine worm's shell-building mechanism has sparked the recent development of what might be the ideal bone fracture adhesive. The sandcastle worms lives in a mineral shell made from sand glued together by the worm's own adhesive secretion. The glue adheres to surfaces in aqueous solutions, does not dissolve, is relatively strong, and last year, Russel Stewart of the University of Utah figured out how it works. "The worm 'secretes two little dabs of glue onto the [sand, shell or other] particle,' says Stewart. 'And the building organ puts it onto the end of the tube and holds it there for about 25 seconds, wiggling it a little to see if the glue is set, and then it lets go. The glue is designed to set up and harden within 30 seconds after the worm secretes it.'" The molecular ingredients include a mixture of proteins and ions that create a specific charge,. In addition, the acidic gland that the glue is made in plays another vital role because when the substance is exposed to the alkaline water, it very quickly sets to form a very strong adhesive. And now Stewart has taken this magnificient biological adaptation and used the molecular knowledge to engineer a synthetic bone glue that not only functions like the sandcaste worm adhesive, but actually works better.

This glue is made out of two synthetic polymers with the same chemical groups and a similar electrical charge to that of the worm's glue-like secretion. "'We made polymers with side chains that mimicked the positive and negative charges in the worm glue,' Stewart says." The result is a synthetic bone glue that is twice as strong as the worm secretion and sets from liquid to solid based on temperature as well as acidity. In addition, though only early tests have been conducted, the glue appears to be non-toxic and biodegradable.

The benefit of this biomimetic technology for the healthcare industry would be tremendous. Fractures are common injuries and though simple, linear types can heal on their own and large fractures can be set with pins and screws, more complex fractures that are too small to set with pins are very hard to repair properly. This glue would be inexpensive and would require simplified procedures than current broken bone repair. In addition, the glue sets very quickly allowing the patient to regain function and mobility without the aid of inserted metal screws or pins. The glue also biodegrades, theoretically leaving the healed, native bone in its place, even for the most complex fractures. The development of a safe and effective adhesive that can be used in aqueous solutions has been a long time coming. Current glue alternatives are too toxic to be used in deep tissues and are used only in superficial skin wounds or in elderly people in which toxicity over the long term is not as much of an issue, such as in hip replacements. The glue might also be used to adhere tissue scaffolds to bone in cancer patients and to deliver drugs to sites that bone fragments are glued. Stewart expects the synthetic worm glue will be tested on animals within a year or two, and will be tested and used on humans in five to 10 years.