Flexing MUSSELS

Mussels have been the scourge of boat hulls since mankind first set sail. Built to withstand the corrosive powers of the sea, these mollusks are nearly impossible to dislodge once they take root. Aside from when sautéed with white wine, mussels are frequently considered no more than a pest, but their reputation may soon improve. A team of researchers at the Massachusetts Institute of Technology recently found a way to make use of the sticky bivalves. The glue secreted by mussels when latching onto the surfaces of rocks and boats has provided a recipe for a gel that stabilizes damaged blood vessels and has the potential to treat numerous cardiovascular diseases.

Dr. Christian Kastrup, assistant professor at the University of British Columbia’s Michael Smith Laboratories in the Department of Biochemistry and Molecular Biology and lead researcher on the project, was searching for an underwater adhesive that would not easily wash away under blood flow. He wanted to develop an alternative to the usual mechanical treatments for atherosclerosis, such as stents, which can cause significant damage. “We were really interested in finding a way to gently implant materials onto blood vessel walls,” he explains. A special glue was one option under consideration.

Surprising Results

He asked around different departments at MIT in search of inspiration. The interdisciplinary team he assembled kept a running list of possible adhesives, but one in particular stood out. “Other researchers had found that the proteins mussels use to stick to rocks worked extremely well and could be mimicked in synthetic systems.” Kastrup was both skeptical and intrigued, but decided to give it a shot.

The process involved experts in the fields of polymer chemistry, controlled release, transcatheter procedures, radiologists, and pathologists. After much tinkering in the lab, the researchers formulated a synthetic version of the glue using an alginate base. The adhesive gel was then applied in a thin layer via catheter over plaque build-up in the vessel walls in mice. Surprisingly, it was able to withstand blood flow for months before degrading, and left a stabilized vessel in its wake. The results were even better than Kastrup had imagined.

“It’s what we had set out to do, but I had many doubts in mind. I was really surprised, especially by how long it adhered.” In preliminary studies, the glue stayed put for about one to four months, but researchers believe it has the potential to last even longer. “That is one thing we still have to evaluate,” he says.

Far-Reaching Benefits

Kastrup experimented with drug-elution by adding steroids to the gel. The drug-infused adhesive formed a protective cap over the plaque and released the medication, leading to reduced macrophage content and plasma cytokine levels. Inflammation diminished and rupture no longer appeared to be a threat. Mechanical drug-eluting devices have been used to achieve the same results, but can cause damage of their own.

The benefits of the glue could be far-reaching if it receives approval for human application. Cardiovascular disease is still the number one cause of death in the United States, with one out of every three people dying of a heart attack or stroke. Kastrup’s mussel gel may be able to help prevent the clots that often lead to these events by stabilizing damaged vasculature and preventing plaque from breaking off and blocking blood flow. Unfortunately, many years of research and trials are ahead before the gel can be translated into practice.

Though it is yet to be tested for uses beyond cardiovascular issues, the glue may be able to treat other maladies. “This material can be adhered to any region of vasculature where a catheter can reach, so potentially it could treat a number of different conditions, such as stabilizing aneurysms and embolizing tumors,” Kastrup says. The current research has focused on painting thin layers over the endothelium, but such afflictions would necessitate larger implants of the glue. Kastrup is optimistic it will be an effective therapy for these conditions and looks forward to testing the theory.

The invention of the synthetic mussel glue functions as a reminder that great breakthroughs can come from unexpected places, such as Alexander Fleming’s discovery of penicillin. It is still too soon to know if the mussel glue will revolutionize therapies for atherosclerosis and other vascular damage, but Kastrup and his colleagues are continuing their research. Now working in the Vancouver, British Columbia, area with the ocean and its many bivalves just a stone’s throw away, it seems possible that his next big idea might also come from the sea.

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