Once implanted, coronary artery stents to prop open blood vessels usually remain in place for the rest of the patient’s life. The longer a stent is in place, the greater the risk of late-stage side effects. That's why researchers are trying to develop a bioabsorbable stent, one that will gradually and harmlessly dissolve after the blood vessel is healed.

Studies have investigated iron stents, which can rust, and magnesium-based stents, which dissolve too quickly. So, researchers at Michigan Technological University, Houghton, are trying something different—zinc.

After placing tiny zinc wires in the arteries of rats, they discovered that the wires degraded at a rate just below 0.2 millimeters per year, which, they say, is the "magic" value for bioabsorbable stents for the first three months. After that, the corrosion accelerated, so the implant would not remain in the artery for too long. On top of that, the rats' arteries appeared healthy when the wires were removed, with tissue firmly grasping the implant. In addition, they say there are additional benefits as zinc reduces atherosclerosis, the development of plaque in the arteries.

The only potential draw back, they say, is that the zinc is not strong enough on its own to hold open an artery. It would need to be an alloy, but it would have to be one that would allow the corrosion to occur. The researchers have filed a provisional patent on their discoveries and are now testing new zinc-based stent materials.

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