Nanomedicine: Small particles with huge potential

Inserting tiny particles into the human body to repair cells, fight disease and even detect illness long before symptoms appear sounds more like the plot summary of the classic 60s sci-fi movie Fantastic Voyage than an emerging field in medicine. But researchers around the world are discovering a wide array of ways in which nanotechnology may be able to revolutionize medicine.

Nanomedicine involves using particles the size of molecules to deliver substances including drugs, heat and light to specific cells in the human body. The goal is to more closely target the delivery of therapeutic and diagnostic materials to both diagnose problems on the cellular scale and also to minimize the exposure of healthy cells to potentially damaging substances like those used in chemotherapy.

While nanomedicine is in its infancy, there are more than 60 drugs and drug-delivery systems and 90 medical devices and diagnostic tests that use nanotechnology currently being tested at labs around the world. Nanocrystalline silver, a metal which has the ability to kill bacteria, is already being used in hospitals to fight infections. The particles, which are less than a thousandth the diameter of a hair, are deposited on medical equipment to kill the bacteria responsible for the 2 million hospital infections and more than 90,000 annual patient deaths. The company that developed this technology is currently at work on creating a similar nanotech-based treatment that can be applied to implanted medical devices like breast implants, replacement joints and pacemakers.

Cellular diagnosis and treatment options for cancer

One area of particular interest to researchers is how nanomedicine can be used to diagnose and treat cancer at its earliest stages. The National Cancer Institute has created a division devoted to exploring this topic, the NCI Alliance for Nanotechnology in Cancer.

The Alliance includes specialists in both the public and private sector who are working to adapt nanotechnology to radically change the way cancer is diagnosed, treated and could be prevented. Among the focus areas of the Alliance are:

• agents that detect changes in cells and prevent precancerous cells from becoming malignant
• imaging tools that can detect cancer before symptoms appear
• devices that can deliver drugs directly to cancer cells
• nanotech methods to help lessen the severe side effects of many cancer treatments

Quantum dots or qdots have shown potential as a tool for diagnosing cancer on the cellular level. These miniscule multi-colored fluorescent semiconductors are injected into cells and act as what researchers at PinnacleCare Center of Excellence UCLA and Stanford call “biological probes.” The qdot-injected cells are then monitored to see what other molecules they interact with, whether these interactions are normal and what signaling pathways are being used for the interactions. In essence, it is a built-in cell surveillance system. Researchers at the NCI Center for Cancer Research are using qdots in a similar way to help determine if cancer has spread to the lymphatic system.

At the University of Michigan, researchers led by Dr. James R. Baker are working to create a nanoengineered particle that functions as a complete system with the ability to target, image and kill cancer cells. The gold nanoparticles have polymers that branch off the surface. These polymers can be loaded with molecules that can target cancer cells, fluorescent agents that help make imaging the cells more precise and drugs that can destroy the unhealthy cells. Once a sufficient number of these nanoparticles have entered the cell, physicians can use lasers or infrared light to heat the gold core of the molecule creating what’s called a nanobomb. The particles explode when heated and kill the tumor.

Researchers at other institutions are conducting similar studies with nanoparticles made of silica, gold-covered glass beads and polymer shells also known as nanoshells. Making chemotherapy more effective and decreasing its side effects is the goal of studies currently in progress by a team from Harvard Medical School and MIT. They are encapsulating the chemotherapy agent doxetaxel in nanoparticles which then attach to the cancer cells and release the drug directly into those cells. In addition, specialists at Perdue University are creating gold nanoparticles that can identify marker proteins on breast cancer cells which will make very early diagnosis possible in about four years they predict.

Battling Alzheimer’s and building stronger bones

Nanomedicine is also targeting other diseases including Alzheimer’s Disease (AD). Scientists in Europe are using lightly radiated gold nanoparticles to destroy the beta amyloid fibrils and plaques which are believed to cause mental decline in patients with AD. The technology also holds promise for the treatment of other neurodegenerative diseases including Parkinson’s disease.

When a patient has a hip, knee or other joint replaced, new bone must grow on the implant for it to work effectively and comfortably. Biomedical engineers at Brown University are treating the titanium implants so that they grow carbon nanotubes on their surface. When they placed bone forming cells on the treated implants, they discovered the cells grew twice as fast as they did on untreated implants. More calcium was also formed on the treated implants.

A great deal of attention is being focused on using nanotechnology to markedly improve the early diagnosis of disease processes on the cellular level. One lab has developed a test that checks the DNA in an exhaled breath for cancer biomarkers which can help determine the patient’s risk for developing lung cancer. Another researcher is working on a blood test that will be able to determine if a person has been exposed to a biological or chemical agent in the event of a bioterror attack.

“While most of these nanotechnology advances are still in their early stages, many hold exciting promise for a future where we can be truly proactive in our detection and treatment of disease,” says PinnacleCare Chief Medical Officer Dr. Miles J. Varn.