Casting new light on cancer treatment
Twinkling like stars against the night sky, gold nanoparticles produce distinctive pulses of light while gyrating in sync with a rotating magnetic field. Measuring about 100 nanometers from tip to tip, the nanostars may hold the promise for early cancer diagnosis.
The near-infrared pulses from the nanostars can pass through biological tissue more easily than visible light, and may someday allow pathologists to detect tumors at an earlier stage of development.
“This is a very different approach to enhancing contrast in optical imaging,” says Alexander Wei, a professor of chemistry and member of the Purdue University Center for Cancer Research. “We don’t want to oversell this new technology, but we hope it will prove useful in developing methods for early detection.
“Brighter isn’t necessarily better for imaging; the real issue is background noise, and you can’t always overcome this simply by creating brighter particles.With gyromagnetic imaging, we can zero in on the nanostars by increasing signal strength while cutting down on background noise.”
Nanomedicine also is casting a new light of sorts on the search for more effective cancer treatments. Dr. Debbie Knapp and Professor Jim Leary are investigating how antibody-targeted nanoparticles can treat urinary bladder and other cancers. They’re starting with the treatment of mice, then will follow with dogs and ultimately humans.
Nanotechnology has the potential to address the collateral damage that often accompanies traditional chemotherapy. Many cytotoxic drugs don’t differentiate between normal and cancerous cells and end up wiping out both, causing not only short-term side effects like hair loss and nausea, but also long-term, devastating ones, like damage to nerves and organs.
Targeting also could provide a more individualized approach to cancer care someday. “The cancer that one person gets, even if it looks the same in a microscope, is different from the cancer another person gets,” says Knapp, the Dolores L. McCall Professor of Veterinary Medicine and a specialist in canine cancer care.
“There will be a time in the future when a person’s cancer can be analyzed at a molecular level and then nanoparticles will be designed to treat that individual’s cancer. It’s not like the shotgun approach of standard chemotherapy. It’s more of an individual way of delivering cancer drugs. And this should be a much more successful approach.”
Striving for a new standard
Knapp’s work with canines complements that of her colleague, Professor Sulma Mohammed.Two years ago, Mohammed and her colleagues discovered similarities between pre-malignant mammary lesions in dogs and humans. Because the lesions appear spontaneously in dogs and because dogs are exposed to the same environmental risks as humans, that makes them an ideal model for determining which lesions will develop into cancer and which ones won’t.
Since mammography has become the gold standard in screening for breast cancer, many more women are diagnosed with abnormal cell growth than ever before. Because the lesions are considered risk factors for cancer, their discovery drives preventive care.
Hormonal therapy is usually prescribed if the lesions are estrogen-receptor (ER) positive. No treatments are available, however, when women have high-risk or ER-negative lesions. By studying tissue samples of dogs, Mohammed can see if malignancies develop and also determine which medical interventions are most likely to prevent their occurrence.
“To stop any disease, you need to develop a model of intervention,” says Mohammed, an associate professor of cancer biology. “Dogs provide an animal model for preclinical work, essentially biological studies so that we can understand the disease better before we try treatments on humans.”
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