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A SUGAR coating could help keep arteries clear after surgery.

Clearing clogged arteries is one of the most common operations, with over 2 million people worldwide treated each year. But an angioplasty, as the procedure is called, can damage the lining of arteries, leading to blood clots and new blockages. One way to prevent this is to implant scaffolds known as stents to prop arteries open.

Now Maryam Tabrizian鈥檚 team at McGill University in Montreal is developing a different approach 鈥� 鈥減aving鈥� over the damaged area. The team has shown that depositing ultra-thin layers of complex sugars can greatly reduce clotting.

First, they deposit a thin layer of chitosan, a strong bio-adhesive that binds to muscle cells exposed by the loss of the arterial lining. Next, they add a layer of another polysaccharide called hyaluronan. The process is repeated to build up 10 alternating layers, creating a coating just 70 nanometres thick. Both chitosan and hyaluronan are naturally occurring sugars with inflammatory properties that are already used in medicine.

The team then placed damaged pig arteries with and without the coatings in blood. Clotting was dramatically reduced in the coated arteries: 87 per cent fewer platelets adhered to the lining. The coatings last only a few days, but that is enough time for an artery鈥檚 protective lining of endothelial cells to regrow.

The procedure can also be used to deliver drugs. In other experiments, Tabrizian trapped small amounts of an amino acid called L-arginine between the layers. L-arginine is converted into nitric oxide, which increases blood flow. These fortified coatings reduced platelet adhesion even further, to 91 per cent overall (Journal of the American Chemical Society, DOI: 10.1021/ja034321x).

Tests in pigs, using a special catheter to apply the coating, suggest the technique works just as well as it did in the lab, Tabrizian says. If human trials are successful, the technique could be adapted for many kinds of surgery.