The ‘bear bones’ behind contracting osteoporosis


    By Jade McDowell

    It is every college student?s dream to be able to sleep for six months straight, but in order to do it they will have to learn some secrets from the bears.

    A visiting professor will speak at BYU Thursday about why hibernating bears don?t get osteoporosis, a disease in which bones become fragile.

    In humans, extended inactivity, such as bed rest or spinal cord injury, causes bones to weaken within a matter of weeks. The bones become porous, meaning they develop thousands of tiny holes like a sponge, making them much easier to break.

    In contrast, bears hibernate for up to six months out of the year and do not lose any bone mass or strength during the long period of inactivity. Professor Seth Donahue, biomedical engineering professor from Michigan Tech University, is working to understand why.

    Donahue said he became interested in this research 10 years ago when he learned that bears do not lose muscle mass during hibernation. He wondered if the same thing applied to their bones.

    ?Muscles are adaptable to their mechanical environments, which you can easily see with weight lifters,? he said. ?The more they use those muscles, the stronger and bigger they get. The same thing happens to bone strength and porosity.?

    So he began studying black bears. He obtained blood samples from live black bears in captivity and also the femurs of bears killed by hunters in Michigan.

    ?We found out the bones don?t lose mass during hibernation,? he said. ?In fact, they become less porous.?

    Donahue is working to apply his findings to human bones to prevent bone loss, especially after inactive periods. His team has sequenced and synthesized the gene for the bear parathyroid hormone, which regulates calcium and which he believes may be the key.

    The team has been injecting the synthesized hormone into rats with decreased bone density, and has had encouraging results. Donahue said he hopes the research will eventually lead to new and improved osteoporosis drugs.

    He has been collaborating with several people across the country, including Hal Black, BYU professor of plant and wildlife studies.

    ?This has direct relevance for human health, especially for females with osteoporosis,? Black said.

    Black, who studies black bears in Utah, has served as a valuable resource for post-hibernation bear bones. Donahue?s home state of Michigan only allows bear hunting in the fall, which means before Black?s help, Donahue only had access to pre-hibernated bones.

    Janene Auger, an assistant research professor who started working with Black as an undergraduate student, said they also have access to older bears than the East Coast due to less hunting pressure.

    Black and his research team contacted Donahue when they heard about the project and offered to help collect more diverse samples.

    ?The hunters in Utah over the past several years have received mail and phone solicitation describing how to collect femurs from the bears they take and why this effort is important,? Auger said. ?We had a good response and were able to get about 50 bones per year.?

    Black said he invited Donahue to present his research at BYU because he feels it is something that students and professors alike could learn from.

    ?He?s reached a point where he?s coming up with strong conclusions about osteoporosis,? Black said.

    Donahue will present his research on Thursday at 11 a.m. in 234 MARB.

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