Meat glue and crustacean shells form the right recipe for patching wounds

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A Wyss Institute team has leveraged a commercially-available enzyme called transglutaminase to directly bond chitosan biomaterial to bodily tissue(Credit: Wyss Institute at Harvard University)

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The kitchen and the laboratory have come together at Harvard's Wyss Institute for Biologically Inspired Engineering, where researchers have developed a method that allows a biodegradable, and biocompatible bioplastic derived from the chitin shells of crustaceans and insects to be used to patch up wounds or hold implanted medical devices in place. The technique involves combining the material with a cutting edge culinary ingredient called transglutaminase or "meat glue".

Wyss Institute Founding Director Donald Ingber and Javier Fernandez are responsible for a chitosan bioplastic dubbed "Shrilk" previously developed at Wyss, andhave now extended the potential for the material into clinical areas. Chitosan, which is already approved for clinical use, boasts coagulant and antimicrobial properties and is used in a range of applications, from agricultural biopesticides to coagulant powders for controlling bleeding in emergencies.

The Wyss team saw chitosan bioplastics as having greater clinical potential, but the problem was how to bond them to living tissue. They found the answer in transglutaminase – a natural protein-binding enzyme that's more popularly known as meat glue. It's used commercially for food processing tasks like making seamless stuffed tenderloins, caseless sausages, and bacon-wrapped beef medallions without using skewers.

By combining chitosan with transglutaminase, the team found that they could use the bioplastic and glue to bond tissues together. In addition, they were able to develop different formulations to create different types of chitosan that can bond to many types of material.

The simplest involves laying down a sheet of chitosan over serious injuries and using transglutaminase to secure it in place. The team has already demonstrated this application using a removed pig intestine with a large hole in it. Under pressure tests, the patch was found to be stronger than the intestinal tissue itself.

Another version is a spray made of liquid chitosan and liquid transglutaminase that can be used to quickly seal wounds. When it was used on a pig lung through which air was pumped to simulate breathing, it was able to seal a puncture wound. According to the team, the spray version of chitosan could be used to cover large areas, including serious burn cases.

Chitosan foam bonded to a one-centimeter-long defect in explanted porcine muscle(Credit: Wyss Institute at Harvard University)

A foam version is designed for the most serious of wounds, like those found on battlefields or in car accidents. Such a foam could be used to fill wound cavities and staunch bleeding until the patient can be moved to hospital.

The Wyss team sees the new chitosan dressings as having applications beyond keeping wounds closed and protected against infection. The technology could also be used to bond inorganic materials to living tissue, like holding biomedical implants or microfluidic devices in place in the body.

"Right now our approach is very general, but we could theoretically take this concept and adapt it into almost any form imaginable for a broad number of possible uses," says Fernandez.

The research was published in Tissue Engineering.

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