A team from Rensselaer Polytechnic Institute has found—for the first time—how the protein osteocalcin plays a significant role in the strength of our bones. The findings could lead to new strategies and therapeutics for fighting osteoporosis and lowering the risk of bone fracture. This work, led by Deepak Vashishth, Ph.D., head of the Department of Biomedical Engineering at Rensselaer, is the first to give evidence of fracture at the level of bone’s nanostructure. Additional partners include Villanova University, the Hospital for Special Surgery in New York, and Yale University.
Funded by the NIH (National Institutes of Health), the study recounts how fractures in healthy bones begin with the creation of incredibly tiny holes, each measuring only about 500 atoms in diameter, within the bone’s mineral structure. In the case of a slip, trip, or fall, the force of the impact on a bone physically deforms a pair of joined proteins, osteopontin and osteocalcin, and results in the formation of nanoscale holes. These holes, called dilatational bands, function as a natural defense mechanism, and help to prevent further damage to the surrounding bone. However, if the force of the impact is too great—or if the bone is lacking osteopontin, osteocalcin, or both—the bone will crack and fracture.
“This study is important because it implicates, for the first time, the role of osteocalcin in giving bone the ability to resist fracture, ” Dr. Vashishth said in the December 11, 2012 news release. “Since osteocalcin is always the point of fracture, we believe that strengthening it could lead to a strengthening of the overall bone.”
“Currently, all of the advice for treating osteoporosis is related to calcium. We believe there’s more to the story than just calcium, and the results of this new study raise an important question about vitamin K. Leafy green vegetables are the best source of vitamin K—wouldn’t it be great if eating spinach and broccoli was not only healthy, but also good for your bones? We plan to investigate this link in future, ” Dr. Vashisth said.
Asked what specifically he would like orthopedic surgeons to know about this work, Dr. Vashisth told OTW, Risk for fracture, in particular osteoporotic fractures, is also dictated by the quality of bone matrix of which osteocalcin and osteopontin are key components.
As how he will proceed with further research, Dr. Vashisth commented to OTW, “Use human cadaveric models to investigate loss and/or modification of osteocalcin and osteopontin in bone matrix with aging and diseases.”
