Researchers from Duke University have developed a bone bandage that accumulates pro-healing adenosine molecules to accelerate bone repair.
Bone fractures are complex, difficult injuries resulting in prolonged and sometimes incomplete repair. One way of approaching new treatments for bone fractures involves delivering new bone cells, which can promote healing. Yet, delivering these cells is limited by the challenge of high costs and limited engraftment of transplanted cells. As an alternate approach, the Duke researchers developed a method to mobilize bone tissue to augment its healing abilities thanks to a special biomaterial.
The research team noted that the body produces a high amount of adenosine molecules after bone injuries, and that increasing access to it can help accelerate bone repair. Yet, the amount of available natural adenosine can be limited, resulting in insufficient repair. Thus, they developed a bone bandage to sequester adenosine molecules to the site of bone injury. They used a polyethylene glycol (PEG) network, functionalized with boronate molecules, which bind adenosine and slowly release it over time.
To test the potential of this approach, the researchers applied it in a mouse model with tibia fractures. They found that mice treated with the therapeutic bandages were healing faster than those without the boronate molecules. Three weeks later, the mice with therapeutic bandages had greater healing than those without, showing better bone formation, higher bone volume, and better vascularization.
Image: Healing progress of a fracture in a mouse treated with a new type of bone bandage that traps native adenosine (top), is preloaded with external adenosine (middle), and has no adenosine at all. The sequestered adenosine clearly helps the breaks heal faster to the naked eye up to 14 days, with cross sections of the bones showing more density and vascularization after 21 days.
“Adenosine is ubiquitous throughout the body in low levels and performs many important functions that have nothing to do with bone healing,” said Prof. Shyni Varghese, senior author of the study and professor at Duke University. “To avoid unwanted side effects, we had to find a way to keep the adenosine localized to the damaged tissue and at appropriate levels. We’ve demonstrated that this is a viable approach and filed a patent for future devices and treatments, but we still have a long way to go. The bandages could be engineered to capture and hold on to adenosine more efficiently. And of course we also have to find out whether these results hold in humans or could cause any side effects.”
The publication in Advanced Materials: In Vivo Sequestration of Innate Small Molecules to Promote Bone Healing