Angiogenesis, the growth of new blood vessels, plays a critical role in several chronic human diseases, including metastatic cancer. In fact, several new anticancer therapies are designed to starve tumors by shutting down angiogenesis, but the lack of a good assay for quantifying angiogenesis in the body has hampered the development of effective antiangiogenesis therapies.
Late fall 2008, researchers at The Siteman Center of Cancer Nanotechnology Excellence described a novel nanoparticle capable of imaging angiogenesis using magnetic resonance imaging (click here to see earlier story). Now, researchers at the University of California, Berkeley, have developed a second type of nanoparticle that can image angiogenesis using positron emission tomography (PET). The investigators, led by Jean Fréchet, Ph.D., describe their new nanoparticle in a paper published in the journal Proceedings of the National Academy of Sciences of the United States of America.
The investigators used a nanoparticle known as a dendrimer, a spherical polymer with multiple chemical functionality built into its structure. This chemical functionality enabled the investigators to incorporate radioactive bromine-76 into the core of the dendrimer and add a targeting agent to the outside of the dendrimer. For a targeting agent, the researchers used cyclic-RGD, a well-studied peptide that binds strongly to the integrin avb3, a protein expressed only on the surface of new blood vessels. The dendrimer itself was designed to degrade in the body once imaging is complete.