Plastic surgery

Human tendons inspire soft surgical sutures

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McGill University researchers have developed sutures inspired by human tendons, which mitigate the damage typically caused by stiff surgical sutures while offering the possibility of personalised wound treatment.

Sutures are indispensable for closing wounds, having the capacity to exert larger force than tissue adhesives and speeding up the natural healing process. There are many materials which have been adopted for this purpose – such as degradable and nondegradable plastics, biologically derived proteins, and metals – but their performance has been limited by their stiffness. This can cause discomfort, inflammation and impaired healing, among other post-surgical complications.

In an effort to remedy this problem while expanding functionality for sutures, a team of Montreal researchers developed tough gel-sheathed (TGS) sutures which contain a slippery but tough gel envelope. Their work has been documented in Science Advances.

According to the researchers, part of the problem with conventional sutures is the mismatch between our soft tissues and the rigidity of sutures which rub against contacting tissue. They approached this problem by developing a new technology which mimics the mechanics of tendons.

“Our design is inspired by the human body, the endotenon sheath, which is both tough and strong due to its double-network structure. It binds collagen fibres together while its elastin network strengthens it,” said PhD candidate Zhenwei Ma.

The endotenon sheath forms a slippery surface to reduce friction with surrounding tissue and also delivers materials for tissue repair in a tendon injury, comprising cells and blood vessels and mass transport and tendon repair.

The McGill University sutures contain a popular commercial braided suture within a gel envelope mimicking this sheath. The TGS sutures can be fabricated up to 15cm long and can be freeze-dried for long-term storage. Using first a porcine skin and then a rat model, the researchers demonstrated that they can be used for standard surgical stitches and knots and are effective for wound closure without causing infection.

The TGS sutures – in another parallel with endotenon sheaths – can also be designed to provide personalised wound treatment. The researchers demonstrated this principle by loading the sutures with an antibacterial compound, pH sensing microparticles, drugs and fluorescent nanoparticles for anti-infection, wound bed monitoring, drug delivery and bioimaging applications.

“This technology provides a versatile tool for advanced wound management,” said Professor Jianyu Li. “We believe it could be used to deliver drugs, prevent infections, or even monitor wounds with near-infrared imaging. The ability to monitor wounds locally and adjust the treatment strategy for better healing is an exciting direction to explore.”

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