30,000-year old mammoth tusk could reveal new information about bone loss

Researchers at The University of Western Ontario's Schulich School of Medicine & Dentistry are using a section of 30,000 year old woolly mammoth tusk, unearthed in the Yukon, for modern medical research. Stephen Sims, a physiologistin the Musculoskeletal Health Research Group at Western, studies the cells that cause bone loss. He's hoping the ancient ivory will provide new insight which could lead to novel therapies for osteoporosis and other diseases of the bone.

Sims got the three foot long section of mammoth tusk from Grant Zazula, a paleontologist with the Yukon government. Up to now, Sims and his team have studied samples of ivory, mostly from elephant tusk kindly provided by the Canadian Wildlife Services. Sims and Zazula want to know if mammoth tusk has different properties from modern ivory.

"An enticing possibility is that mammoth tusk will be more transparent than modern ivory, which will allow us to better monitor the process of bone loss. We speculate this could arise due to the process whereby dentinal (tooth) tubules, small channels present in dentine, become mineralized over time," explains Sims. "The properties of mammoth tusk have not been studied in this way before. We are optimistic that we'll be able to marry mammoth tusks with medical research to bring new life to old relics."

Sims is particularly interested in the osteoclast, the cell responsible for the destruction of bone. Osteoclasts are large, multinucleated cells that secrete hydrochloric acid and digestive enzymes onto bone, causing it to be resorbed. Skeletal remodeling is a normal physiological function, but excessive bone loss can occur in osteoporosis and rheumatoid arthritis, resulting in skeletal fragility. The osteoclast cell is the target for therapies aimed at preventing excessive bone loss in these conditions.

To study osteoclast function, thin sections of bone, or dentine, are machined, and then coated with bone cells. The mammoth tusk will be cut into tiny slices, much finer than a hair, and then coated with bone cells. After several days they'll be examined by microscope for small pits, which would be evidence of osteoclastic resorption.

Sims is a Professor of Physiology and Pharmacology and Associate Vice-Provost in the School of Graduate and Postdoctoral Studies at Western. His research is supported by the Canadian Institutes of Health Research (CIHR) and the Canadian Arthritis Network.

The research team includes graduate students Ryan Shugg and Ben Wheal, Research Scientists Alexey Pereverzev and Natsuko Tanabe, and Jeff Dixon, a researcher in the Musculoskeletal Health Research Group and co-director of the CIHR supported Joint Motion Program at Western.

Sims and Dixon have a unique expertise in studying osteoclast biology. Their laboratory is one of only a few in the world that applies an array of techniques to study the electrophysiology, cell signalling and movement of osteoclasts. The lab is internationally recognized for its expertise and has conducted research for pharmaceutical and biotechnology companies investigating novel antiresorptive agents, and characterizing defects in osteoclasts isolated from genetically modified mouse models.

Video of Stephen Sims discussing and showing the mammoth tusk can be found at: http://www.youtube.com/watch?v=FAsD1zcuhgs