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Friday 25th May 2018

Nano-tech treatment for tumours

10th February 2009

Microbiologists are now using a technique called electroportation to accomplish various tasks at the cellular level.


The technology is often used to punch temporary holes in cell membranes for the insertion of drugs or genes, but it could help fight cancer too.

AngioDynamics of Queensbury, New York, announced that their new device, the NanoKnife, eliminates cancerous tumour cells while leaving the cells around them virtually intact.

In addition, the operation causes the patient no physical pain.

Prototypes of the device have been installed in 17 medical centers worldwide, 5 of which say they actively use it. It has been tested upon 37 patients so far.

In order to remove tumours without the use of chemical treatments, doctors use a technique called ablation, which heats or cools tumour tissue until it has died.

In this type of operation, there are a lot of non-cancerous tissues that end up dying as well, and internal bleeding becomes a potential problem.

The adoption of this new technique for removing tumours could have profound effects upon treatment results, because electroportation does not produce enough heat to destroy surrounding tissues.

Stephen Kee of the University of California at Los Angeles Medical Center compared ablation to an egg being boiled. He said that the real Achilles' heel of ablation techniques is the destruction of blood vessels.

Tumours that arise near larger blood vessels may experience a problem known as the heat sink effect, in which the flow of blood cools the area around the tumour, putting pressure on the doctor to raise the temperature.

The NanoKnife can deliver quick bursts of energy through its electrodes, which are inserted into the tumour and placed around it.

Its pulses, which create an electrical field of up to 3000 volts per centimeter, can last up to 100 microseconds.

Ions then rush through as cells somewhere near the electric field make pores in the fatty membrane of the tumour.

Electroportation, when done with a voltage lower and less frequent than that of the NanoKnife, allows the cell to close in response to the electrical pulses.

The process of reversing electroportation is often used by microbiologists to modify the genetic material inside stem cells.

With the NanoKnife, cells respond to the electrical pressure by staying open, then the cell initiates a kind of suicide known as apoptosis, and dies.

Tissue varies from organ to organ in its conductivity, and the main difficulty in using the NanoKnife is to properly space the electrodes from one another so that a spherical electrical field can be created around it.

These electrodes have either one pole or two poles, which influences the breadth they should be given from one another.

However, the operator of the NanoKnife will not need to be so well trained in its use that he or she memorises all of the appropriate information.

Mark Ortiz of AngioDynamics says that a software system is being developed that will yield a protocol of treatment planning based on medical imaging.

The software will use medical imaging data to plot a series of points where electrodes may be placed for optimal performance.

The older technique of ablation is still advancing, too, and some doctors remain skeptical about electroportation.

Francisco Garbagnati said that his patient group is having very good results with ablation when working near blood vessels, and that he doesn't think electroportation could solve the problem of bleeding.

His speciality is thermal ablation involving radio frequencies and low watts, using thin electrodes to work on the parts of the liver rich in blood vessels.

It remains to be seen if electroportation will have any unforeseen effects on blood vessels, although studies have suggested that they will remain intact.


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