Drug-coated scaffolds prevent scar tissue from forming in arteries

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July 3, 2003 – As a longtime trucker and owner of an expedited freight company, Elton “Tony” Brazeel knows the value of just-in-time delivery. But he never expected to benefit from it in the operating room.

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The Michigan man was among the first in the nation to get a drug-coated stent, the same day in April that the U.S. Food and Drug Administration approved the tiny, pop-up metal scaffolding implanted in arteries and coated with medication to keep arteries from clogging. He had four blockages and his doctor, cardiologist Kirit Patel, first told him of the advanced medical device only days before.

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“All of a sudden, they called me on the phone and … said, ‘Can you come in tomorrow (for surgery)?'” said Brazeel, 68. He was at St. Joseph Mercy-Oakland Hospital in suburban Detroit the next morning, and Patel placed two stents in Brazeel’s arteries as part of an angioplasty.

The new stents have given Brazeel — and the stent market — a second chance.
Like today’s stents, the first-generation models were three-dimensional devices made via a laser machining process used for micromechanical devices. The bare-metal stents proved promising initially, but soon ran into some problems. Within about six months, about 30 percent to 35 percent of the arteries would renarrow and reblock because of scar tissue.

With the recently approved drug-coated stent from Johnson & Johnson’s Cordis Corp., the renarrowing rate drops to as low as 5 percent, Patel said, depending on the size of the patients’ arteries. The drug is steadily released from within special polymers placed on the stent.

Patel said the new technology will be useful in a majority of angioplasties, a common technique for clearing blocked arteries. “I think this is a big boom for patients — it will keep them (from coming) back to the hospital. … It will save a lot of health care dollars in the long run. This is truly a cure for a significant amount of patients.”

Brazeel’s first stent implanted a decade ago didn’t work, and he was in the hospital a few months later undergoing open-heart surgery. Patel said Brazeel was the “perfect candidate” for the new drug-coated stent. “I think this is going to work really well for him — another bypass would have been pretty dangerous. It’s an important breakthrough for this patient population.”

Micromachined devices also are providing breakthroughs in other areas of life science.
Germany-based STEAG microParts GmbH has developed a microspectrometer that enables the BiliChek, a handheld tool that analyzes light reflected from a baby’s forehead, to detect jaundice.
 
Respironics Inc. of Pennsylvania bought the BiliChek product line earlier this year from Georgia-based SpectRx Inc., which plans to incorporate STEAG’s microspectrometer technology into some of its future products.

STEAG also developed the Respimat aerosol inhaler sold by Germany’s Boehringer Ingelheim GmbH. The metered-dose inhaler processes liquid through a micronozzle and delivers precise doses of drugs without environmentally harmful propellant gases.
Advances in stents also continue on several fronts. Several companies vie with J&J in the market, such as  Medtronic Inc. Guidant Corp. and Boston Scientific. The University of Michigan and University of California, Berkeley, are developing new approaches to designing and making stents cheaper, faster and smaller.

“As the technology matures, you can get tinier and tinier stents … that will allow arteries that were never a possibility before to be done,” said Marlene Bourne, a MEMS analyst for In-Stat/MDR. “Researchers are even looking in other places besides cardiovascular, such as (neurological) use of stents.”

Medtronic has invested in a microtechnology that could one day complement — or even compete with —  stents.

The Minneapolis-based medical device maker last year bought a minority stake in EndoBionics Inc., with an exclusive option to license the San Leandro, Calif.-based startup’s MicroSyringe technology. The micromedical device, based on MEMS technology from UC Berkeley, is designed to inject drugs directly into the outer membranes of diseased arteries. The drugs then permeate the vessel’s layers with limited trauma and bleeding.

Although it has not yet been tested on humans, the MicroSyringe could provide a safe and effective way of preventing the reclogging of arteries caused by angioplasty and stents, EndoBionics officials say.

For his part, Patel welcomes advancements, but he said the success of drug-coated stents has set the bar pretty high. He cited numerous clinical trials and the treatment
of thousands of patients in Europe before FDA approval. The results show that the drugs effectively penetrate the arterial wall, he said.

“If they want to inject a drug, the results have to be better than what we’ve got … but there’s still some room for improvement,” he said.

One area for improvement, he said, is cost. A new stent sells for $3,100 — compared with $800 for the bare-metal stents. But he’s optimistic that competition will bring that cost down, especially if Boston Scientific’s new drug-coated stent receives FDA approval as expected later this year or early next year.

History is on the side of price cuts. Patel said bare metal stents hit the market a decade ago at $2,200.

Joanie Sams, Brazeel’s wife, said the most valuable thing for her has been watching her  husband improve — and hopes he can steer clear of the operating table. “It’s amazing what the (stent) is doing and how it’s working,” she said. “It sure beats the hell out of going through open-heart surgery.”

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