Sticky proteins from sea mussels

How to mend a broken heart

Feb 18, 2020 | ANDREA SIX

If the heart muscle is damaged, repairing the constantly active organ is a challenge. Empa researchers are developing a novel tissue adhesive inspired by nature, which is able to repair lesions in muscle tissue. They have taken advantage of the incredible ability of marine mussels to adhere to any kind of surface.

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Inspired by Mother Nature: Sea mussels resist the stormiest surf with ease. They hold on to the surface with protein threads. Empa researchers are using this property for a novel tissue glue for wound treatment. Image: Pixabay

On wind- and wave-swept coasts, they adhere stoically to rocks, boats and jetties: sea mussels. With super powers that make Spiderman turn pale, the mussel's foot holds on to the surface, as its glands produce fine threads which, unlike spider silk, remain firm under water and yet highly elastic. Two proteins, mfp-3 and the particularly sulfurous mfp-6, are components of this sea silk. As structural proteins, they are especially interesting for biomedical research because of their fascinating mechanical properties and their biocompatibility.

Challenging conditions
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The novel biopolymer with mussel proteins exhibits a fine yet robust microstructure. Scanning electron microscopy, 1'000-fold magnification, colored.

Researchers from Empa's "Biomimetic Membranes and Textiles" lab in St. Gallen have made use of these properties. Claudio Toncelli's team was looking for a biocompatible tissue glue that would adhere to the beating heart while remaining elastic, even under the most challenging conditions. After all, if heart muscle tissue is damaged, for instance by a heart attack or a congenital disorder, the wounds must be able to heal, even though the muscle continues to contract.

"Actually, collagen is a suitable basis for a wound glue, a protein that is also found in human connective tissue and tendons," says Toncelli. For example, gelatin consists of cross-linked collagen that would be very attractive for a tissue adhesive. "The structure of gelatin already comes very close to some of the natural properties of human connective tissue," he adds. However, the hydrocolloid is not stable at body temperature, but liquefies. So in order to develop an adhesive material that can securely connect wounded areas on internal organs, the researchers had to find a way to incorporate additional properties into gelatin.

Under pressure
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The tissue adhesive made of mussel protein is able to adapt to the finest structures of complex surfaces, as this impression of a heart-shaped casting mold shows. (colored)

"The muscular foot of mussels excretes strongly adhesive threads, with which the mussel can adhere to all kinds of surfaces in water," explains Toncelli. In this sea silk, several proteins interact tightly. Inspired by nature's solution for dealing with turbulent forces under water, the researchers equipped gelatin biopolymers with functional chemical units similar to those of the sea silk proteins mfp-3 and mfp-6. As soon as the gelatin sea silk gel makes contact with tissue, the structural proteins cross-link with each other and ensure a stable connection between the wound surfaces.

The researchers have already investigated how well the novel hydrogel actually adheres in lab experiments that are usually used to define technical standards for so-called bursting strength. "The tissue adhesive can resist a pressure equivalent to human blood pressure," says Empa researcher Kongchang Wei. The scientists were also able to confirm the outstanding tissue compatibility of the new adhesive in cell culture experiments. They are now trying hard to advance the clinical application of the "mussel glue".

Further Information

Dr. Claudio Toncelli
Biomimetic Membranes and Textiles   
Phone +41 58 765 72 15
claudio.toncelli@empa.ch

Dr. Luciano Boesel
Biomimetic Membranes and Textiles     
Phone +41 58 765 7393
Luciano.Boesel@empa.ch


Editor /Media contact
Dr. Andrea Six
Communications
Phone +41 58 765 6133
redaktion@empa.ch

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Audio

Radio programme on RTS CQFD of February 19, 2020 in french


Audio

Radio programme on SRF1 of March 22, 2020 in German


Audio

Empa researchers have developed a new tissue adhesive that can be used to treat heart muscle damage. The novel adhesive was inspired by sea mussel. They produce the so called mussel silk, which is extremely adhesive. Radio programme on SRF4 News Aktuell of March 5, 2020 in German