Using Magnetic Fluids to Repair Damaged Retinas

Originally Published MDDI May 2002

R&D DIGEST

When the retina becomes detached or torn as a result of disease or injury, vision can be impaired and blindness can occur if the condition is not repaired. A method now in development by researchers at Virginia Polytechnic Institute and State University (Blacksburg, VA) could provide a treatment option that offers a number of advantages over current techniques.

Conventional treatment involves injecting either silicone fluid or a special gas directly into the eye to push the retina back into place. But when retinal damage is severe, treatment can fail because the material cannot reach certain areas of the eye, particularly the lower parts, according to J. P. Dailey, MD, an ophthalmologist with Erie Retinal Surgery (Erie, PA) and a major collaborator in the research. The new method entails the use of injectable magnetic fluids that would be capable of repairing all areas of the retina.

The researchers speculate that use of a magnetized version of the conventional silicone fluid would facilitate repairs and make the process more precise by allowing the fluid to be moved to areas of the eye that are difficult to reach.

According to Judy Riffle, PhD, head of the research team and a chemistry professor at the university, the treatment appears promising in laboratory studies. Riffle says that animal studies could take place within a year, and human studies could soon follow. "We are the first to develop controlled magnetic nanoparticles that are appropriate to use in the eye," Riffle adds.

The Virginia Tech process involves enmeshing tiny particles of cobalt or magnetite in a silicone-based fluid (polydimethylsiloxane). Exposing the material to an external magnetic field enables the fluid to be manipulated similarly to the way that magnetic pieces are moved around in certain toys, says Riffle. Dailey initially developed the concept of using magnetic fluids for the new treatment protocol and discussed the concept with Riffle, a polymer chemist. Riffle then designed the biocompatible silicone magnetic nanofluids.

"If it works, it will be wonderful," says Dailey, adding, "This could be a major innovation in how retinal detachment repair is done." He explains, however, that the technology will still require additional safety testing.

Speculating about other potential applications of the new technique, Riffle says, "Our lab's work may open the door for a whole host of new medical applications for magnetic nanoparticles." Similar magnetic fluids are being developed for use in targeted drug delivery. Riffle and her colleagues are developing magnetic, biodegradable microspheres capable of being attached to specific drugs, such as chemotherapy agents. Using a magnet positioned outside the body, the medicated fluid microspheres could be directed to hard-to-reach tumor sites, such as the lung, prostate, or brain. Riffle believes that a similar technique can eventually be used to deliver DNA to specific cells during gene therapy.

The researchers also suggest that the fluids could be used for magnetic hyperthermia. In this application, an alternating magnetic field passed across a magnetic fluid would cause the particles to heat up and subsequently destroy targeted tissue. Riffle says this method shows promise as a noninvasive means of treating brain tumors.

Certain challenges remain before clinical trials involving the magnetic fluids can begin. Because of the potential toxicity of cobalt, research is progressing with magnetite, which should be less toxic to cells. Riffle's group is also attempting to create silica shells for the experimental nanoparticles. These shells would prevent the fluids from losing their magnetism over time, and would give them the potential to be permanently implanted, Riffle explains.

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