Sutures and staples have long been the go-to for closing up wounds and encouraging wound healing in the healthcare industry. While both wound-closing methods offer a host of benefits — they are quick and offer low risk of infection, among other benefits — they tend to offer less precise wound alignment, sometimes resulting in garish scars.

As such, researchers from all over the globe have devised solutions, some of which were inspired by nature, for sealing and healing wounds without commonly used sutures or staples.

Skin yarn

Researchers led by the University of Bordeaux in France have developed a yarn-like material derived from human skin cells.

To create the so-called skin yarn, the team grew skin cell fibroblasts — the cells that encourage the production of fibers and collagen — on sheets of material. The team then reconfigured the material into shapes like strings for suturing applications. According to the skin yarn developers, the material could also be braided or knotted and woven into human textiles to create various valves and tubes.

Medical textiles containing human skin could potentially encourage wound healing or possibly replace parts of damaged human organs without running the risk of rejection. According to the developers, the body will be less likely to reject the woven human textiles because they are natural human cells rather than the synthetic agents often rejected by the human immune system.

Salamander secretions

Researchers from Harvard Medical School have suggested that the mucus secretions from the Chinese giant salamander can be used to seal and heal wounds, potentially better than the synthetic adhesives currently in use.

SSAD performed better than other synthetic glues, oftering strength, flexibility and limited scarring and inflammation. Source: Deng et al.

The nature inspired bio-adhesive, called SSAD, is derived from salamander skin secretions that are freeze-dried and combined with a saline solution, which creates a gel-like glue. This gel-like glue reportedly closed wounds and expedited healing in both pigs and rats in the lab, according to its developers. The research team reported that the mixture performed better than current synthetic adhesives used in medical settings in lieu of staples and sutures.

When trialed on pigs and rats, the bio-adhesive demonstrated strength and flexibility and reduced inflammation and scarring. The team observed that SSAD closed a bleeding wound on a rat in less than 30 seconds and healed skin wounds on diabetic rats during testing. A few weeks after application, the SSAD degraded entirely inside the rats' bodies.

Glue

MeTro is applied directly to the wound and activated with light. Source: University of Sydney

A team of biomedical engineers from the U.S. and the University of Sydney has developed an elastic and surgical glue that helps heal wounds in place of surgical staples and sutures.

The glue, called MeTro, is designed to close wounds that present a risk of expanding and reopening, and it can also be used to seal hard-to-reach internal wounds.

When exposed to ultraviolet (UV) light, the glue can set in roughly 60 seconds and it contains a degrading enzyme that can be modified to last as long as is necessary to ensure adequate healing time.

Northeastern University professor and lead study author Nasim Annabi said: "The beauty of the MeTro formulation is that, as soon as it comes in contact with tissue surfaces, it solidifies into a gel-like phase without running away."

"We then further stabilize it by curing it on-site with a short light-mediated crosslinking treatment. This allows the sealant to be very accurately placed and to tightly bond and interlock with structures on the tissue surface."

Likening the process to the silicone sealants often found surrounding bathroom and kitchen tiles, researchers determined that MeTro responds and interfaces closely with human tissue to promote healing, is stored easily and can be applied directly at the site of a wound or cavity where it helps encourage healing and degrades without leaving behind any signs of toxicity.

Mussel-inspired adhesive

A team from Michigan Technical University has developed an underwater smart glue that can transform itself from sticky to solid in under 10 seconds when a small amount of electricity is applied to it.

With potential applications that include wound healing, the glue uses catechol, which is a synthetic compound that mimics the sticky and wet proteins secreted by mussels. Catechol has previously been used to mimic mussel and adhesive proteins, but this marks the first instance where electricity has been applied to deactivate the catechol. The application of electricity, according to the team, is reportedly easier than using pH, is easier to incorporate into electronics and it enables easy detachment.

This is just a sampling of the sealing and suturing alternatives in development across the globe. Check back with Engineering360 for more on the latest developments in healthcare engineering.