Medical Device Daily Contributing Writer
VICTORIA, British Columbia – A Swiss-born pharmaceutical professor at the University of British Columbia (UBC; Vancouver) has won a grant from the Canadian Institutes of Health Research (Ottawa, Ontario) to explore the use of what he called magnetic "bandages" to treat diabetic leg ulcers, cancerous tumors and rheumatoid arthritis.
Urs Hafeli, PhD, told Medical Device Daily that he believes the bandages could replace the use of chemotherapy in the treatment of some cancers.
"The problem with chemotherapy is that it goes everywhere in your body. It's very potent and for sure will kill the tumor. But very often the drug goes to other organs that are healthy and also does damage to those organs."
About the size of the human fingernail, the magnetic bandage operates on the same principle as the larger therapeutic superconducting magnets that have been used to treat cancer. Both rely on digital fluoroscopy systems to track the path of the microspheres.
With this strategy, Hafeli proposes pursuit of a two-fold treatment: First, tiny magnetic particles or microspheres containing cancer-fighting drugs or radioactive materials are injected into the patient's bloodstream. Then, the magnetic bandage is placed over an open wound or above a tumor to draw the microspheres directly to the area of the body to be treated. Drugs are then slowly released from the microspheres.
"We need to make sure the magnet is above the tumor," Hafeli says. "So first we do imaging to see where the tumor is, and we put a magnet over it. We then inject the particles, stop them and concentrate them in the tumor and from there irradiate or treat the tumor."
Such a system has been used in the labs of FeRx (San Diego) and with remarkable initial results, says Hafeli. In one trial, 32 patients suffering from liver disease were injected with radiolabeled magnetic microspheres, which were tracked to the disease site using digital fluoroscopy. What X-rays revealed was a significant uptake of microspheres and cancer fighting drug directly into the tumor.
Unfortunately, Hafeli notes, FeRx folded about a year ago, and the clinical effects on the patients were never made public (Medical Device Daily, May 4, 2004).
"But the results were quite good," he adds. "X-rays show the microspheres ended up in the area of the liver they were targeting."
Made of materials ranging from polymers like gelatin and albumin to glass, the microspheres are about 1 micron in size, or about 1/25,400 of an inch – thus small enough to travel through capillary blood vessels, pulled along by a large external magnetic force.
"They have to be a little bit smaller than the red blood cells because you don't want to clog the capillaries," says Hafeli.
Use of polymers in the human body is not new; surgeons have been using polymeric sutures for at least two decades. And like polymeric sutures, microspheres are biodegradable and eventually disappear from the body.
"You can use what people normally call these 'slow-release' applications, or you could actually chemically bind the drug to your microspheres. Its enzymatic action breaks off the drug, and then the drug is free to do the treatment."
Hafeli believes those with diabetes could be the first to benefit from his magnetic bandage.
Diabetics often suffer from open leg wounds or ulcers that fail to heal after three or four months, thereby putting them at risk for infection – or much worse. About 5,000 people in Canada, for example, have their legs amputated each year as a result of diabetic leg ulcers. In the U.S. the figure runs closer to 80,000 a year.
Another application for microspheres, says Hafeli, could be in the field of gene therapy. Some genetic researchers already are using small magnetic particles to attract genes to human cells and, he says, doing it "faster, much more efficiently and with much less material" than conventional gene therapy.
"The results in cell culture experiments are very nice, very clear. It's just great," he says.
But this greatest excitement is reserved for the potential use of microspheres and magnetic bandages to treat cancers, especially those nearest the body surface, such as skin cancer.
"For the ones where we have relatively good access to the tumor – where we are within reach of the magnetic field from the outside – I think this technology would be a good choice. It should work," says Hafeli.
One challenge the technology faces is developing microspheres that are sufficiently magnetic to be attracted by the magnetic bandage.
Hafeli's work at UBC will involve a multi-disciplinary science team, with its main task being to seek out "the perfect particle" to produce a more magnetic microsphere, he says.
A second problem is balancing the toxicity of drugs with the number of microspheres injected into a patient's blood stream.
"You have to use very active drugs, because you don't want to inject huge amounts of these microspheres. There is always the danger that you will clog capillaries if there are too many of these particles."
Doctors using microspheres and magnetic bandages would also be limited to treating local disease; they would not be effective in treating metastases. That's because magnetic forces tend to fall off relatively rapidly with distance, so that a cancer that is very deep in the body would be beyond the scope of the magnetic bandage.
Hafeli has tested the use of microspheres and magnetic bandages with good results using rabbit models. More extensive animal studies, and eventually human studies, are likely to follow, but the technology is not expected to be available in hospitals for at least a few more years.
While Hafeli is still one of only a few scientists in the world exploring the use of magnetic microspheres and magnetic bandages, he sees a growing interest in their potential uses. "The group that is working with magnetic bandages is expanding around the world."
Hafeli says he laughed when a reporter asked him recently if his ideas conjured up the movie classic, Fantastic Voyage. But the association actually is no laughing matter, he acknowledges, since it "really is the stuff of science fiction."