July 21, 2017 -- There’s a lot more to know about sharks than their bite.
Sharks heal quickly from wounds. They don’t get cancer very often. And they resist infections.
While little evidence supports those uses, researchers are studying sharks in hopes that they can help human health. (Experts also urge pregnant women to avoid eating shark meat because it has high levels of mercury.)
“There have been a handful of discoveries about shark immune systems and compounds that look promising for applications to human medicine," says Mahmood Shivji, PhD, a geneticist and director of the Save Our Seas Shark Research Center at Nova Southeastern University in Fort Lauderdale, FL. "There's so much more we can learn from these ancient vertebrates.''
Although in its early stages, research on sharks is increasing and has great potential, agrees Jennifer Schmidt, PhD, a molecular biologist, geneticist, and director of science and research for the Shark Research Institute. WebMD asked the two experts to elaborate on the most promising areas.
Wound Healing Lessons
Whale sharks often suffer severe injuries to their backs when boat propellers strike them, Schmidt says. "It's not unusual to see a shark with a big slice through its back starting to heal six months later," she says. A year later, she says, the injury is often barely noticeable.
This quick-healing ability, as well as sharks' ability to resist infections, is of great interest.
Shivji’s team is sequencing the entire shark genome. "We are trying to understand what makes a shark a shark," he says, including why it heals quickly.
By looking at which genes sharks use as they heal, scientists might be able to develop or find drugs that could turn on the genes to promote healing, or turn off the ones that slow it down, Schmidt says.
At least one wound-healing product already on the market borrows from the shark's healing ability. Called Omnigraft, it includes shark cartilage as well as silicone and cow collagen. The FDA has approved it to treat serious burns and diabetic foot ulcers.
Squalamine as a Germ and Cancer Fighter
Shark liver has a compound called squalamine that has antiviral and antibacterial properties.
Researchers are testing squalamine to see if it can combat different types of bacterial infections.
Other studies have found that the compound can help prevent the formation of blood vessels that feed cancerous tumors and help them to grow.
Supplements containing squalamine are sold as a dietary supplement but are not regulated by the FDA. Research to date does not prove that oral supplements can fight infection or cancer. They can also have serious side effects such as liver toxicity, nausea, fatigue, and anorexia, and they should not be combined with certain antibiotics or chemotherapy medications.
IgNAR Antibodies as a Cancer Fighter
A shark antibody known as IgNAR may also someday help fight cancer, Shivji says. This antibody has properties that may help scientists make a more targeted cancer therapy for people, he says.
In targeted therapy, a drug is attached to an antibody and then carried to the tumor cells to fight the cancer. The IgNAR antibody can enter the cancerous cells more easily and penetrate the cells more thoroughly than others used in targeted treatment.
Scientists are researching how to use the shark antibody as a model for one that could be used in humans, Shivji says.
In his research, Shivji has found two genes in sharks that may help explain their robust immune system and why they may resist getting cancer. The two genes have equivalents in people that are linked with cancers of the breast, colon, and prostate, he says.
However, in sharks, these genes have adapted, Shivji found, perhaps explaining their continued good health. His research is continuing, but he cautions: "We don't want to give the impression that if you eat shark, it's going to cure or prevent cancer."
Shark Skin for Hospital Surfaces
A material that mimics the skin surfaces of sharks, which can resist algae, barnacles, and other organisms, is sold as a covering for hospital surfaces.
Its aim, Shivji says, is to cut bacterial growth and lessen dangerous infections that hospitalized patients can get.
Shark-Like Protein to Fight Fibrosis
Australian scientists have developed a humanized version of a shark protein known as the i-body. Early animal studies found it lowers the thickening and inflammation in lung tissues in people with pulmonary fibrosis. The drug may also help fight other diseases, such as liver problems and eye problems.
The FDA granted it orphan drug designation status, which helps speed drug development. The company hopes to start studies on people soon.