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Atomic-Scale Nanoparticles Promise New Era in Medicine
By Daniel J. DeNoon
WebMD Health News
Reviewed by Laura J. Martin, MD
June 21, 2011 -- New technology now makes it possible to create atomic-scale drug particles, diagnostic tools, and biological medical devices -- and the FDA is struggling to regulate the fast-growing field.
Noting the "critical need to learn more" about the impact of nanotechnology on medicines and medical devices, the FDA has issued a warning that it intends to regulate the field -- and has asked for help in understanding the impact the new technology will have on FDA-regulated products.
It's a welcome development, says nanomedicine developer Gang Bao, PhD, director of the Center for Pediatric Nanomedicine, a joint project of the Georgia Institute of Technology, Emory University, and Children's Healthcare of Atlanta.
"It is a great thing that FDA now pays attention to nanotechnology," Bao tells WebMD. "We can always publish scientific papers, but what we really want to do is have nanomedicine used in the clinic: for drug delivery, diagnosis, or treatment using nanomachines. Without FDA approval we cannot do that. So therefore this is a very important advance."
Nanotechnology already is a trillion-dollar industry spanning fields from agriculture to product packaging. It springs from new technology that makes it possible to manipulate matter at the atomic scale. The application of this technology to medicine is truly revolutionary, says Jamey Marth, PhD, director of the Sanford Burnham Center for Nanomedicine at the University of California, Santa Barbara.
"It will be comparable to what occurred 50 or so years ago when Watson and Crick discovered the structure of DNA and its role in biology," Marth tells WebMD. "We are going to witness a huge increase in the understanding of disease and in the ability to treat, detect, and ultimately cure disease with nanomedicine."
What Is Nanomedicine?
It's difficult, but important, to grasp the scale of the nano world. A nanometer (nm) is a billionth of a meter. A single sugar molecule is 1 nm in diameter; the DNA helix is 2 nm in diameter. A typical virus is 75 nm in size. A red blood cell is 7,000 times larger than a nanometer.
"Why this size? Inside a living cell we have proteins, we have DNA molecules, etc., all on a nanoscale," Bao says.
"Just a few decades ago, a computer used to be the size of a room," says Marth. "Now everyone has a laptop. It's the same thing in biology. We are seeing the miniaturization of biology, which will rapidly change the way we do research and develop drugs."
By allowing scientists to take such a close look at biological processes, nanotechnology offers new tools to understand what causes disease. We've been able to learn a lot by cracking the DNA code. But genetics doesn't tell us all the biology we need to know.
"We have not been able to answer all of the questions about a lot of important diseases -- grievous diseases such as diabetes, cardiovascular disease, diseases of aging, cancer. All these diseases have some genetic underpinning, but the genetic role is partial," says Marth. "What nanomedicine is able to do is to begin to identify and interrogate those processes which are outside our genetic inheritance."
That's only part of the story. Nanotechnology also offers powerful new tools to treat disease.
The FDA already has approved two cancer drugs based on nanotechnology: Abraxane and Doxil, which package cancer drugs into nanoscale lipid droplets and allow higher chemotherapy doses with fewer side effects.
Second-generation drugs of this type will carry nanoparticles on their surfaces that not only target the drugs to cancer cells, but also allow them to penetrate deep into tumors. The FDA has given the green light to clinical trials of Cornell dots -- nanoscale silicon cages that carry nanoparticles to tumor cells.
Marth says that nanomedicine will speed the discovery of biomarkers that identify diseased cells. Once these biomarkers are found, they can be used to bind therapeutic nanoparticles only to the cells that need them, leaving normal cells alone.
Bao's team is pioneering another approach: using nanoparticles to repair genetic mutations. Their first target will be the mutation that causes sickle cell disease.
"We are trying to develop nanodevices to fix this mutation," Bao says. "We use a nanoscissors -- technically a zinc finger nuclease -- to cut the DNA at a pre-described location. At the same time, we supply a piece of DNA that has no mutation. In repairing the DNA cut, the cell actually uses the template we supply."
Is Nanomedicine Safe?
A major task for the FDA will be to set guidelines for demonstrating that new nanomedicines are safe. But Marth says there are both toxic and nontoxic approaches to nanomedicine.
"We will have to do clinical trials, but we are not adding poisonous materials to the body," he argues. "The way forward is to take natural products, rearrange them in ways that do new things, but allow them to be degraded normally in the body."
Even so, Bao says the FDA guidance will be important, as materials that behave one way on a normal scale can behave quite differently at a nanoscale.
"There might be some unique features of nanoparticles that induce some toxic effects," Bao suggests. "If they could get into the body, stay in the cells, not be cleared, there might be some harmful effects down the road, and we need to understand that. We do not think the particles we use have any intrinsic toxicity, but we need to know this for sure."