Putty could revolutionize how broken bones mend
Lisa Chapman describes her broken leg as possibly the worst pain she’s ever felt — taking the trash to the curb outside her Baldwin house two weeks ago, missing a step, and then hearing a dreadful pop in the back of her leg as she fell.
“I literally crawled on all fours. It was awful,” she said, describing how she got back in the house.
The Centers for Disease Control and Prevention said about 4 million people fractured bones in 2010, the last year for which data is available. Depending on the type of break, healing can be complicated and subject to surgery, infection and incomplete joining of broken ends, said Dr. MaCalus Hogan, an orthopedic surgeon and researcher at the University of Pittsburgh.
But researchers from Carnegie Mellon University and Allegheny Health Network think they have found a way to speed the healing of complex fractures with an inexpensive and easily stored biological product that doctors in emergency rooms, battlefields and developing nations could use. A product they call “bone putty” went through early clinical trials in South Africa, and the makers hope to ramp up trials in the United States.
“There is nothing like this anywhere,” said Phil Campbell, a research scientist at the Institute of Complex Engineered Systems at CMU and one of three founders of Carmell Therapeutics, the Oakland-based company that makes bone putty.
The other founders are Lee Weiss of the CMU Robotics Institute and Dr. James Burgess, a neurosurgeon at Allegheny General Hospital.
Bone putty works by providing a concentrated amount of wound-healing and bone-building proteins to the two fractured ends, encouraging it to heal, said Campbell. It’s applied by syringe to the small gap between the fractured ends after they’re set.
In the bone putty’s clinical trial, 30 patients with broken tibiae and open wounds were treated with the product. Ten were treated with the traditional protocol.
Researchers followed their progress for a year.
None of the patients had an adverse reaction to bone putty, said Campbell.
Healing in the treated group took weeks less than in the control group, he said. What surprised the researchers was that the recipients of bone putty had fewer infections at the wound site than the control group.
The formulation, said Campbell, did not include antimicrobial medicines. He said they are unsure how bone putty affects patients’ immune systems.
“It was a real finding,” he said. “There’s a lot of potential there.”
Bone putty is made from plasma, the part of blood that does not include red blood cells. In a drop of plasma are platelets, the cells that make up blood clots, and proteins such as fibrin and fibroblast growth factor, which enable wound healing.
The team at Carmell takes discarded human plasma from blood banks and adds a little calcium to start the clotting process. They dry the clotted plasma and turn it into a powder.
That powder, when reconstituted with glycerin, acts like plastic.
It can be mixed with everything from antibiotics to ceramic, said Campbell. The end result is anything from a pizza dough-like bone putty to flat sheets that researchers hope could go into quick-healing bandages.
Carmell Therapeutics was founded in 2007, said CEO Alan West. Its principals decided to go to South Africa for their first human trials because, West said, it was faster and more straightforward than doing trials in the United States.
The company is looking for investments to fund the next set of trials, he said, and has ventured outside Pittsburgh to find money because of a lack of life-sciences venture capital.
He said they want to keep the company in Pittsburgh and to introduce the product in 2015.
“That’s the tip of the iceberg — the broken bones,” West said. “We see other applications, including in sports medicine.”
Hogan, the Pitt orthopedist, said the findings are promising, especially in bone putty’s effect on infection. He studies how platelet-rich plasma, the same starting material that goes into bone putty, affects tendon healing.
He said one big question is determining under what conditions a concentrated amount of wound-healing and bone-building proteins becomes a benefit or a danger.
“There are a number of materials in this area,” he said. “We don’t know which factor is doing what, and at what concentration. We have to be very responsible with the application of this technology.”
Megha Satyanarayana is a Trib Total Media staff writer. Reach her at 412-320-7991 or [email protected].