New, multi-functional material promises more effective tendon repair
Tendons connect muscles to bones – strains or injuries to tendons are especially debilitating because the fine tissue never fully regains its former mechanical strength, thereafter, resulting in reduced mobility. Now, a team of researchers at Harvard’s Wyss Institute in Boston, US, have developed a unique two-faced biomaterial that promotes tendon healing and maintains its function. Additionally, the new material can be loaded with and releases drugs into the injured area to reduce scarring and inflammation.
Named after the Roman god with two-faces, the Janus Tough Adhesives (JTAs) consists of two different surfaces: one contains chitosan, obtained from the shells of crustaceans, which firmly bonds to tendons to keep two sides of a tear together to improve healing. At the same time, the opposing surface uses plain hydrogel to help the tendon glide against other tissues during movement.
Results were promising when the JTAs were tested a series of experiments using animal and human tissue. On isolated pig tendons still covered in blood, the JTAs bonded more strongly than other tissue adhesives. The material was also implanted into patellar, foot flexor, and Achilles’ tendons of live rats, and found that they bonded strongly and non-invasively. Similar results were seen in tests using human cadavers.
In further tests, the team encapsulated corticosteroid drugs into the hydrogel, which would help reduce inflammation during healing and the formation of scars afterwards. Tests in rats with injuries to their knee tendons showed that inflammation passed much more quickly.
“Importantly, when we applied JTAs to ruptured patellar tendons of rats, they remained in place over their three-week implantation and facilitated tendon healing,” said postdoctoral fellow Benjamin Freedman. “They also reduced the formation of scars by 25% compared to surgically repaired tendons that we didn’t treat with JTAs.”
Freedman and his team are developing JTAs as off-the-shelf biomaterials for easy use for surgery. All the biomaterial components in JTAs, including chitosan, are biocompatible and already used in other medical applications.
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