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Sunday, 22 September, 2002, 23:01 GMT 00:01 UK
Gene therapy keeps blood flowing
Re-blocking after heart procedures is frequent
Re-blocking after heart procedures is frequent
Gene therapy given after treatment to unblock clogged-up arteries could help them stay clear, according to research.

Narrowing of blood vessels can increase the chance of heart attack or stroke, and one treatment is to insert and inflate a balloon in the affected section, then put in a metal tube to stop it closing again.

However, the insertion of the tube, called a stent, can actually trigger a reaction in some patients which leads to rapid re-blocking of the blood vessel.


We expect it will only take about two years to complete pre-clinical studies before we can begin human trials

Professor Seppo Yla-Herttuala, University of Kuoppio
Researchers at the University of Kuoppio in Finland believe they understand why the stent causes this process.

They also think they can halt this reaction by introducing an extra gene into the blood vessel.

Experiments in animals suggest that this approach may work.

Vicious cycle

The key is what happens in the lining of the blood vessel when the stent is put in.

The process inevitably slightly damages this lining, called the endothelium, and it reacts by sending out a chemical "distress" signal.

This provokes the body to produce other chemicals called "free radicals", which cause damage to more endothelial cells, starting a vicious cycle which results in the re-furring of the blood vessel.

In this situation, another chemical is supposed to be produced to counteract the negative effects of the free radicals, but this is not happening in patients suffering from restenosis.

Inserting gene

The researchers believe that injecting the gene which produces this protective chemical could redress the balance.

When this gene was inserted into the genetic make-up of deactivated viruses, then injected into white rabbits, they noticed a distinct difference.

At two weeks, the group given gene therapy had 10 times fewer of the immune cells linked to destructive inflammation of the artery lining.

After four weeks the difference was 20 times less.

It may be possible to give the drug to humans just after the stent is put in, reducing the chance of restenosis.

There are still fears over the safety of gene therapy, but researchers believe that it can be tested in humans relatively soon.

Professor Seppo Yla-Herttuala, who led the project, said: "We expect it will only take about two years to complete pre-clinical studies before we can begin human trials."

The research was published in the journal Circulation.

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