Researchers Develop Surgical Stitches Loaded With Anti-Inflammatory Medications

Deep cuts from accidents or surgeries require stitches, typically followed by oral anti-inflammatory medications like ibuprofen. While these medications help with pain, they don’t specifically treat the wounds. Consequently, the stitches’ site can become inflamed, which could slow healing and result in scarring.

However, Ouachita Baptist University researchers are developing stitches loaded with anti-inflammatory drugs to deliver medication directly to the injury.

Mieya Kirby, an undergraduate researcher working with chemist Sharon K. Hamilton, presented results at the spring meeting of the American Chemical Society (ACS).

When Kirby was a child, her mother underwent breast reconstruction surgery, which involved anastomosis, or suturing together blood vessels. “If there’s inflammation at the site of suture, that can quickly close up that blood vessel, and those sutures can fail,” Kirby said. This can cause scars, reopen wounds, trigger infections or, as with breast reconstruction surgery, kill surrounding tissue. Her mother’s experience inspired Kirby to look for alternatives that would minimize sutured vessel inflammation.

In Hamilton’s laboratory, Kirby works with electrospun polymers, which have emerged as an attractive material for wound-healing technologies. Under high voltage, polymer solutions are drawn into delicate nanofibers that can be molded into different shapes, including dissolvable stitches, and provide a surface for regenerating tissues.

Take, for instance, polydioxanone, a polymer already used for dissolvable surgical sutures. The material does not interact with living tissues and maintains its strength for weeks. After the wound heals, these sutures break down, turning into simpler biomolecules that are metabolized by the body or passed in urine.

In previous work, scientists have coated polydioxanone sutures with anti-inflammatory drugs by dipping the strands in solutions containing these medications. But the drug molecules don’t hold on to the polymers tightly, which isn’t ideal for wounds that take longer to heal. And the dipped strands release the anti-inflammatory drug quickly in the body, which can interfere with the synthesis of collagen—the protein that provides tissues with the scaffolding required to heal the wound. “New collagen is laid down between the two- and four-week mark,” Kirby stated. “So, you need something that won’t be released immediately.”

The researchers mitigated the quick-release problem by blending polydioxanone with another polymer that binds anti-inflammatory drugs during the electrospinning process. The drugs are attached to the new polymer by covalent bonds. The bonds break down gradually, ensuring that the attached anti-inflammatory drug is released into the wound slowly over weeks.

The team is experimenting with different polymers, probing how fast they release drugs and how adjustable those release rates are. These new stitches could eliminate the need to remember to take oral pain medications. Moreover, by reducing inflammation and limiting scars, they could increase the success rates for anastomosis procedures.

In the future, the researchers plan to scale up their solution from thin electrospun polymers to a fiber that is sufficiently strong and flexible for surgeons to stitch. The team is seeking collaborations that would allow them to test the new stitches in animal models. This would be a critical step toward commercialization, as it would test how the drug-release rate changes with scale and whether any preexisting conditions could hinder its use in certain patient groups.

The researchers are also looking at electrospinning other biomedical polymers into sutures. Blending in an antibacterial polymer, for example, could make the stitches resistant to bacterial infections. Likewise, “We could combine the drug-loaded polymer with other materials to make not just an anti-inflammatory suture, but something that helps rebuild the collagen even quicker,” Hamilton noted.

The research was funded by the Arkansas IDeA Network of Biomedical Research Excellence program through a grant from the National Institute of General Medical Sciences and a grant from the National Institutes of Health.