Advances in NanomedicineDecember 2007
By Christopher Windham
Imagine a future when tumor cells can be directly targeted with chemotherapy, eliminating a cancer patient’s systemic exposure to harmful side effects and even death from toxic chemo reactions.
Nanotechnology scientists—with the financial help of endowed universities, the federal government, and private venture capitalists—believe that this fantasy may become a reality within our lifetimes.
Although the debate about the validity of using nanotechnology in medicine continues, the emerging field of nanomedicine is gaining momentum in the medical device and drug-delivery arenas. As scientists explore ways of incorporating nanotechnology to treat disease and prevent illness, many believe nanomedicine has the potential to revolutionize medicine.
The Emerging Science of Nanomedicine
Nanomedicine, a derivative of nanotechnology, is the science of controlling molecular structures to create precise materials and devices.1 This technology centers on scientists’ ability to structure these materials and devices at the molecular scale to address medical problems through research and clinical practice. These “nanodevices” and structures would then be used in human biological systems at the molecular level for monitoring and repair purposes. Physicists predict that this precise approach could be used, for example, to repair damaged tissues, such as bones, muscles, or nerves.
“There are certain things we can do today and there are certain things we’ll be able to do tomorrow,” says Robert Freitas, a Senior Research Fellow at the Institute for Molecular Manufacturing. “For example, when we have nanorobots 20 years from now we’ll be able to find all the cancers (in the bloodstream) and kill them. To build them (nanorobots) we’re going to have to go through a step-by-step process.”
A nanometer is so small that it can’t be seen on a conventional lab microscope. But the use of nanometer-sized devices could be effective in medicine, scientists say, as they are roughly the same size in which biological molecules and structures inside living cells operate.
Many of today’s medical tools are too large, and at the cell and molecular level are not small enough to manipulate our tiny cellular components. With more specific and precise nanotechnology tools, scientists say they’ll be able to better treat and diagnose diseases often associated with aging, such as heart disease and cancer.
Whether or not nanomedicine would ultimately be the solution to today’s medical problems will be answered in two phases: the short- and long-term. Nano-based enzymes and other materials are more likely to take effect in the near future. Many of the more disease treatment-oriented benefits will likely occur in about a decade, when programmable medical nanomachines and nanorobots are developed.
Nanomedicine Research Underway
The federal government, academia, and the biotechnology industry have been exploring new ways to better study nanomedicine in recent years.
In 2004, the National Institutes of Health (NIH) launched its Nanomedicine Roadmap Initiative, which was designed to spur a collaborative nanomedicine research effort. Under the initiative, a national network of eight Nanomedicine Development Centers was created to serve as a breeding ground for nanomedicine-based research and technology.2
Scientists hope that nanomedicine research will foster a greater understanding of disease processes, as well as more elegant diagnostic and treatment tools.“The goal is to intervene in the disease process with much greater knowledge,” says Jeffery A. Schloss, co-chair of the trans-NIH Nanomedicine Taskforce.
Joining the NIH are several other groups exploring the utility of the molecular nanomachines, including the Institute for Molecular Manufacturing, the Laboratory for Molecular Robotics at the University of Southern California, and NASA. Government organizations in Europe, Japan, and Iran have also funded forums and research projects exploring nanomedicine. While funding has been scarce, private groups and seed capital firms are also interested in the technology.
Biotechnology company Gilead Sciences sells a drug-delivery mechanism using lipid spheres, or liposomes, of 100 nanometers in diameter, which coat an anticancer drug that treats AIDS-related Kaposi’s sarcoma.3 Another leader in the field of nanotechnology and medicine is Zyvex, which claims to be the first molecular nanotechnology research and development company.
Unlimited Potential: Diagnostics and Drug Delivery
The term nanomedicine is often applied to chemicals, delivery methods, drugs, and diagnostic tools.
To scientists, the potential ways to use nanotechnology in medicine are endless. One approach under study uses nanotechnology in tracking devices called quantum dots. Quantum dots are small semi-conductor devices that emit certain wavelengths of light according to their size. This makes them highly suitable as contrast agents for magnetic resonance imaging (MRI), positron emission tomography (PET), or as fluorescent tracers in optical microscopy. When inserted into the body, quantum dots can penetrate through both the skin and tissue and emit color to signal the presence of cancerous cells. Doctors can then peer into a tumor to find where it has spread by using quantum dots to examine nearby lymph nodes. In contrast, today’s technology calls for the dissection of many lymph nodes by a pathologist to find the malignant tumor. Scientists believe that quantum dots may also be useful as structural scaffolds in tissue engineering.
Furthermore, near-term nanotechnology benefits could be seen in improvements to the drug-delivery process. For example, nano-sized drug-delivery carriers called dendrimers, which are artificial molecules the size of a protein, could be capable of delivering medicine to an exact location. This targeted approach has already made it safer and more effective to render gene therapy in some research labs. The drug-delivery process could also benefit from hollow polymer capsules that release into the body only after swelling or compression.
One of the most promising applications of nanotechnology in drug delivery is the use of nanoshells. These are small, gold-coated glass beads that seek out tumors in the bloodstream when injected. Nanoshells can produce heat by absorbing light. By binding them to antibodies and using infrared light to penetrate the skin and cause the nanoparticles to heat up, scientists may be able to destroy tumors without harming healthy tissue. This technique has already been used successfully in mice by a team at Rice University, which published its results in the journal Cancer Letters in 2004. In the mice, all tumors disappeared within 10 days and did not reappear.6