So You Want to Know: What can lobster shells do for you?

First published in Landings, April, 2013.

It’s not only the meat in lobsters and other shellfish that is valuable to humans. Researchers have found that the shells, which are often discarded, contain a component known as chitosan that has therapeutic and medicinal purposes.

Richard Wahle, a research associate professor at the University of Maine School of Marine Sciences, explained that the shells of lobsters and other crustaceans are made up of many components, including carbohydrates, proteins, and minerals, which create the framework for the shell. Chitosan is a polysaccharide (sugar). “Those [components] give the exoskeleton its characteristics such as color, texture, flexibility, and other biological properties,” said Wahle. Researchers at Purdue University School of Veterinary Medicine in Indiana tested a form of chitosan derived from shrimp and lobster shells to determine whether it could be used to repair damaged spinal cords in guinea pigs. Dr. Richard Borgens, who led the team, said that the research center at the university has already discovered three other therapies for nerve damage which have since been patented.

The researchers tested a form of chitosan to determine whether it could be used to repair damaged spinal cords in guinea pigs. To test this hypothesis, the researchers isolated and compressed a section of spinal cord from a guinea pig. Then they applied the chitosan and added a fluorescent dye which could only enter the spinal cord cells through damaged membranes. If the chitosan repaired the damaged membranes, the spinal cord tissue would be unstained. On the other hand, if the chitosan failed to repair the membranes, the spinal cord nerves would be flooded with dye.

When the section of spinal cord was viewed under the microscope, the researchers were thrilled to see that the tissue remained unstained. They concluded that chitosan had repaired the damaged membranes. The researchers were even more excited when they tested to determine whether the spinal cord could transmit electrical signals to the brain through the tissues repaired by chitosan. They found that 30 minutes after injecting chitosan, electrical signals which previously had been unable to travel through damaged tissues were being received by the brain.

Chitosan has not yet been tested on human patients with spinal cord injuries because the research is still in the early stages. However, researchers are encouraged by the results of the study. Borgens isn’t claiming that chitosan will be a cure for spinal cord injuries but hopes that it can be used to improve the quality of life for disabled people. “There will never be one ‘magic bullet.’ It will take multiple therapies targeted to each phase of the injury process to provide quality of life for those injured,” he said.

In the case of uncontrolled bleeding, as may occur during a military battle, chitosan can be used as a dressing. The material forms an immediate seal of a wound which then allows time for a patient’s own blood clotting mechanisms to take effect. In a technical report published by the Army Institute of Surgical Research in 2004, the authors noted that chitosan has been shown to control external bleeding in experimental studies. A manufacturing company, HemCon Inc., received FDA approval for the use of chitosan dressings to control external bleeding. The company’s final product was recommended for possible treatment of combat casualties in Afghanistan and Iraq.

Another group of medical professionals from the Division of Plastic and Reconstructive Surgery at Northwestern University’s Feinberg School of Medicine reported that chitosan-based dressings have been used in military and other traumatic wound settings where massive hemorrhaging leads to depletion of blood clotting factors. Chitosan-based dressings were used successfully to control bleeding after the removal of dead tissue. The patients would otherwise have required a trip to the operating room or cauterization to control bleeding. More recent research suggests that chitosan may also possess antibacterial properties. HemCon manufacturers report that their chitosan-based hemostatic dressings provide a barrier against a spectrum of nasty bacteria, including the antibiotic-resistant staphylococcus aureus, the source of many infections contracted at hospitals.