August 17, 2005 - Baltimore Sun
Science of tiny generates big developments
Researchers meet in city, discuss nanotechnology
Kathleen Pirollo talked nonstop yesterday, excitedly telling fellow researchers all about the cancer-fighting nanoparticle that she and some colleagues had created.
A millionth of an inch across and known as a liposome, the tiny particle is designed to find a tumor, attach itself and open a pathway for chemicals and radiation. Injected by the millions, liposomes don't cure the cancer on their own, but they make chemotherapy and radiation more effective.
"It works for head and neck cancers, for pancreatic and prostate cancer, wherever it hides in the body," Pirollo said of tests in mice.
Pirollo, a microbiologist at Georgetown University Medical Center, was among 170 researchers at the Johns Hopkins School of Medicine for the initial conference of the fledgling American Academy of Nanoscience, a clearinghouse for cutting-edge medical research that harnesses the power of nanotechnology.
The term "nanotechnology" comes from the word nanometer, which means a billionth of a meter, or about one 25-millionth of an inch. Researchers working on the nanoscale use the world's most powerful microscopes to create and measure the tiniest of objects: molecules, viruses and strands of DNA inside cells.
"Right now, nobody can imagine where all this will lead, but doctors can't do it alone. They're clinicians. We need people with engineering backgrounds, material sciences, mathematics. We want to open up the channels of communications between the doctors and these other scientists," said Dr. Chiming Wei, the academy's president and the director of Hopkins' cardiothoracic-renal molecular program.
For the past decade, nanotechnology has been a key to developing super-strong materials, such as carbon tubes, that are expected to lead to high-performance clothing, microchips and satellites.
But at the two-day conference that ended yesterday, scientists from around the world praised nanoparticles as important tools for delivering drugs to diseased tissues and creating imaging techniques that make it easier to detect cancer and other ailments. While therapies using nanoparticles are still years from approval, a number are being tested in clinical trials. "As a field, nanotechnology is the best hope we've got," Pirollo said.
Some medical researchers work with the same fullerene-based carbon nanotubes being studied by structural engineers. Others work with liposomes and a class of nanoparticles called adenoviruses, which together are used in a gene therapy trials, to enhance imaging technologies used to detect cancer and to deliver drugs to injured tissues and organs.
Pirollo said it took her and Georgetown colleague Ester Chang two years to create their liposome nanoparticle in a project funded by the National Institutes of Health and SynerGene Therapeutics, a small Washington-based research firm.
The liposomes are in preliminary human clinical trials at the Lombardi Comprehensive Cancer Center at Georgetown University Medical Center. "It's not a magic bullet, but it's the bullet that makes everything else work," Pirollo said. "It's like little smart bombs."
Pirollo said that treatments are at least five years off.
Other researchers predicted that nanoparticles might one day be used to repair damaged lung tissue, build stents for heart patients inside the body and enable better hip replacements. They also think nanoparticles will treat both genetically inherited diseases, such as cystic fibrosis, and neurological disorders, such as Parkinson's disease.
But at yesterday's conference, scientists concentrated mainly on one disease. "Most of the possibilities right now are with cancer," Wei said.
A major obstacle in most of today's treatments is that radiation and chemotherapy kill healthy cells along with the cancer. Many cancers also are resistant to drug therapies.
"There are gatekeepers that effectively keep the drugs out of the cancerous cell," said Dr. Alexander Kabanov, a researcher at the University of Nebraska Medical Center.
Dr. Steven Rosenfeld, director of the brain tumor center at Columbia University Hospital, said nanoparticles could be the best hope to defeat the gatekeepers.
He also noted that patients diagnosed with brain tumors have an average survival of less than two years, and treatments are now limited to surgery, radiation and chemotherapy. "It sucks, to put it bluntly," Rosenfeld told 20 colleagues at one of dozens of conference sessions.
When cancer spreads from one cell to another it uses numerous pathways, so blocking just one pathway won't work, he said. He is working on targeting molecular motors that drive cancer cell growth, trying to stop the cancer before it can reach the pathways that send it from one cell to another.
Another problem is that, rather than going directly to infected cells, cancer drugs injected into the blood stream spread throughout the body, an inefficient delivery system.
David Neeham, a researcher at Duke University, said a liposome he discovered in 1996 can be triggered for release when it reaches cancerous tissue cells by applying heat to the damaged tissue.
"With this technique, you have a more site-specific therapy," he said.
His research is funded by Celsion Corp., a Columbia-based firm that supports research into ways of using heat to kill cancer. Clinical trials are planned for the next few months at Duke, he said.