Stem Cell “Fracture Putty” Can Heal Broken Bones?

A new, experimental “fracture putty” created by American scientists from adult stem cells taken from the bone marrow has been shown to speed the healing of bone fractures significantly — and in doing so, may revolutionize the treatment of fractures.

Researchers from the University of Georgia’s Regenerative Bioscience Center (RBC) took adult stem cells that produce a protein involved in bone healing and generation, then incorporated these into a gel they call “fracture putty.” In tests on lab mice, then on larger animals, the putty was shown to help heal bones fast.

To treat fractures, “our approach is biological with the putty,” says Dr. Steve Stice, director of the UGA Regenerative Bioscience Center and one of the lead researchers who created the new stem cell product. “Other groups are looking at polymers and engineering approaches like implants and replacements which may eventually be combined with our approach,” he explains.

The “gel” or “putty” his team created could also be used to improve spinal fusion outcomes, he says. It also has the potential to improve the treatment of facial cranial injuries, which are often seen on the battlefield.

Overall, the stem cell putty has the potential to heal complex orthopedic injuries quickly — and that’s the very reason why the RBC research is being supported by the U.S. Department of Defense.

Between 2009 and 2011, the RBC project received a US$1.4 million grant from the DOD. It’s a collaboration between the RBC researchers and scientists and surgeons from three Texas-based universities, who conducted previous studies: the Baylor College of Medicine, Rice University and the University of Texas.

Dr. Stice and another University of Georgia researcher, Dr. John Peroni, are leading this multidiscipline and multi-institutional bone tissue-engineering project. Right now, the project is testing the “facture putty” on sheep and other “large” animals (larger than lab rats, that is). Dr. Peroni is an associate professor of large animal surgery at the university’s Veterinary Medicine College.

“Complex fractures are a major cause of amputation of limbs for U.S. military men and women,” explains Dr. Stice, who is also an animal and dairy scientist at the UGA College of Agricultural and Environmental Sciences and a Georgia Research Alliance Eminent Scholar.

“For many young soldiers, their mental health becomes a real issue when they are confined to a bed for three to six months after an injury,” he says. “This discovery may allow them to be up and moving as fast as days afterward.”

But to do that, new bone has to be engineered and coaxed to grow.

“Healing of critical-size defects is a major challenge to the orthopedic research community,” says Dr. Peroni. “Large-bone defects must be stabilized. And (this) necessitate(s) technologies that induce rapid bone formation to replace the missing tissue and allow the individual to return to rapid function,” he observes. “To date, no single material can suffice.”

That is, until the new putty was created.

“We have been successful in formulating a product that contains mesenchymal stem cells and allows them to survive in the environment of the fracture long enough to elicit the rapid formation of new bone,” Dr. Stice says.

The team first tested the putty in fractures in rats. After two weeks, the rats were found to be running around and standing on their hind legs with no evidence of injury. Now, the RBC researchers are testing the material in pigs and sheep.

Indeed, the speed in which bone is formed after using the “facture putty” is one of the RBC team’s unique accomplishments.

This year, the team showed that bone could be generated in sheep in less than four weeks.

We’ve tested the fracture putty on “large animals,” “following the guidelines established by our animal care and use committee,” says Dr. Stice.

“The small-animal work has progressed, and we are making good progress in large animals,” says Dr. Peroni.

“The next step is to show that we can rapidly and consistently heal fractures in a large animal,” Peroni says, “then to convert it to clinical cases in the UGA [College of Veterinary Medicine] clinics where clinicians treat animals with complex fractures all the time.”

Once they have something that works for animals, it will be passed over to the DOD for human testing. The RBC researchers expect to wrap up their project by the middle of this year. “By then we are to deliver the system to the DOD,” Dr. Stice says.

For animals, too
Dr. Peroni, who is also chairman of the North American Veterinary Regenerative Medicine Association, says he hopes the material will also be used in the field of veterinary medicine. “This process addresses both human and veterinary orthopedic needs,” he adds.

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