By ED SUSMAN
U.S. researchers said Monday that focused electric pulses can puncture holes into cancer cells, killing those cells without using extremes of heat or cold that can damage other tissues.
In laboratory experiments, a one-minute test utilizing irreversible electroporation destroyed 92 percent of tumors in mice, said Rafael Davalos, assistant professor of biomedical engineering at Virginia Tech in Blacksburg.
The key to this is that it is relatively simple to perform in places such as community hospitals or in resource-limited setting, Davalos told United Press International.
We have already completed laboratory experiments in the test tube and in animals, he said. We expect to begin human trials with this process within a year.
In the treatment, small, needle-like electrodes are positioned around the tumors and electric micropulses are fired. The electric charges open holes in the cell membranes, some of which do not close and cannot be repaired by the cell. These holes are fatal to the cell.
We cannot distinguish individual cells, said Davalos, so some healthy cells within the field of attack would also be killed. But because the system does not heat up cells or freeze, there is no bystander effect in which cells outside the field are killed, he said. This application creates permanent openings in the pores in the cells of the undesirable tissue. The openings eventually lead to the death of the cells.
We were actually quite surprised to find the effectiveness of the system in our animal experiments, Davalos said. He said the efficiency in killing the cells was unexpected because in some cells the electric pulses do not cause enough damage to fatally injure the cancer cells — especially the cells on the periphery of the target.
The researchers successfully destroyed tissue using the electroporation pulses in the livers of male rats. We did not use any drugs, the cells were destroyed, and the vessel architecture was preserved, Davalos said. He describes his work in the special August issue of Technology in Cancer Research and Treatment.
The research by Davalos flows from previous attempts to use electroporation to temporarily open holes in cancer cells. The electric pulses would then be used to drive chemotherapy drugs into the cells to kill them. Davalos said that his system could also be combined with the drugs to kill more targeted cells.
This seems like an exciting new process to kill cancer cells, said Dr. Douglas Scherr, clinical director of urologic oncology at the Weill Medical School of Cornell University, New York. The key is imaging, especially in treating prostate cancer. The most difficult part of prostate cancer treatment is killing the microscopic cancers in the prostate without damaging healthy tissue or other anatomical structures.
Scherr suggested that the irreversible electroporation would prove more effective in treating tumors such as breast cancer, kidney cancer or brain cancer where the malignancies can be more easily imaged. He said that work at Weill is under way in developing more accurate imaging so that only the tumors would be impacted.
The lack of a bystander effect with the electroporation could prove to be an advantage of that type of system, he told UPI.
Davalos and colleagues are working with the National Institutes of Health to use the irreversible electroporation device in brain cancer patients.
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