A clinical study at the Massachusetts Institute of Technology showed that the use of a two-stage nanoparticle drug delivery system was 40 times more effective than a system using a single nanoparticle. The “Stage One” nanoparticle seeks out the tumor cells, and then signals the “Stage Two” portion to deliver the chemotherapy drugs. Researchers tested the delivery system on mice with cancer and found that the two-stage system was more effective in shrinking the tumors than the single-stage method.
Dr. Sangeeta Bhatia, the lead author of the study, and her research team found that the dual-stage method increased the amount of the drug delivered to tumor cells 40 times over the standard procedure. The method also insures that only the tumor cells receive the potentially lethal chemotherapy drugs, without harming the healthy cells surrounding the malignant tumor. When the first-stage particle locates a tumor cell, it sends a signal to the drug-carrying particle for it to deploy its medicine.
“We use the body’s natural amplification processes to get more drug to the target,” Dr. Bhatia said. She also mentioned that she saw the body’s blood clotting system as inspiration for the dual-stage method. When an open wound occurs, the body signals the blood clotting system to close off the blood flow. The system involves an enzyme known as Factor XIII, which crosslinks with a protein called fibrin, which starts the clotting process.
Dr. Bhatia and her team coated their drug-delivery nanoparticle in a version of Factor XIII. When the “scout” particle located a tumor cell, it attacked the tissue and made it bleed. The Factor XIII acted as an attractant to the blood in the tumor cells, thus drawing the drug-delivery particle. The particle then released its payload, with the fibrin clotting the tumor cell and forming a wall to keep the medicine within the tumor site.
This application of nanoparticle technology cold not only lead to more efficient treatments, but also to better tools for early detection. Dr. Francesca Greco, a nanotechnology specialist as the University of Reading in England, said that the dual-stage method, especially the first-stage approach of locating tumor cells, could lead to improvements in early cancer detection. She called the approach “interesting and versatile, with potential applications in tumor diagnostics”.
Despite the early appearances of success behind the dual-stage nanoparticle treatment method, some scientists are still wary of this new development. One argument against it is the level of complexity involved in the delivery system. Dr. Omid Farokhzad of the Brigham and Women’s Hospital in Boston, said that the system “is on the right path”, but that the translation of this method from experiments in mice to clinical trials in humans will take “a lot of work”.
Another issue with this method is how it uses the blood-clotting system to signal the delivery of the chemotherapy drugs. Dr. Anil Sood, an oncology specialist at the MD Anderson Cancer Center in Houston, said that the system should make sure it only triggers blood clots near the tumors and not in more sensitive areas, such as the heart, lungs or brain. “If you’re going to trigger coagulation, you want to be very selective, so that you don’t cause damage in other parts of the body.”
Sources:
http://www.nature.com/news/2011/110619/full/news.2011.374.html
http://www.rsc.org/chemistryworld/News/2011/June/20061101.asp
http://www.genengnews.com/gen-news-highlights/scientists-develop-communicating-nanoparticles-that-boost-targeted-drug-delivery-to-tumors/81245326/
