Bear Bones and Hormones?

By Marcia Goodrich | Published

Black bears sometimes snooze away almost six months out of the year. And while many of us humans would love to spend the winter curled up in a warm den, doctors tell us that's a terrible idea. Our bones aren't designed for constant bedrest and would quickly deteriorate to the equivalent of peppermint sticks.

Bears, however, typically emerge from hibernation with bones as strong as two-by-fours. Why bears are able to dodge the osteoporosis">osteoporosis bullet has been a puzzle. Now, a MichiganTech scientist may have solved the mystery.

During and right after hibernation, bears have a much higher concentration of parathyroid hormone in their blood than they do during the rest of the year, says Seth Donahue, an associate professor of biomedical engineering. And parathyroid hormone is key to bone formation.

Bones are constantly being broken down and rebuilt, in both people and bears. Osteoporosis occurs when bone loss outpaces bone formation, weakening bones sometimes to the point that they fracture.

In people, staying active promotes strong bones. So does parathyroid hormone, but when people are sedentary, parathyroid hormone production doesn't increase as it does in hibernating bears.

"We can't say for sure at this point that parathyroid hormone is what protects bear bones from osteoporosis during hibernation, but the results are very provocative at this point," Donahue said.

Donahue has identified the bear gene responsible for making parathyroid hormone and has synthesised the hormone in the lab. "Our next step is to sprinkle it on bone cells and see if we get activity related to bone formation," he said.

The work holds promise for developing a new drug to reverse osteoporosis, prompting the university to enter into an agreement with Apjohn Group LLC. The Kalamazoo-based business development advisory firm specializes in commercializing life sciences technology.

"Their role is to assist us in developing the commercial potential of this work," said Jim Baker, director of technology and economic development. "They will assist us in seeking research funding and other capital to develop its potential. Ultimately, Apjohn will form a start-up company to commercialize the drug."

"The collaboration with Apjohn is really exciting and will be a useful model for us, since we don't have a medical school," Baker added. "Hopefully, it will result in commercial opportunities that we wouldn't have been able to act on independently."

Michigan Technological University is a public research university, home to more than 7,000 students from 60 countries. Founded in 1885, the University offers more than 120 undergraduate and graduate degree programs in science and technology, engineering, forestry, business and economics, health professions, humanities, mathematics, and social sciences. Our campus in Michigan’s Upper Peninsula overlooks the Keweenaw Waterway and is just a few miles from Lake Superior.