One solution already under way involves using nanoparticles for cancer imaging. By slipping through tiny gaps that exist in fast-growing tumor blood vessels and then sticking together, the particles create masses with enough of a magnetic signal to be detectable by a magnetic resonance imaging (MRI) machine. “This might allow for noninvasive imaging of fast-growing cancer ‘hot spots’ in tumors,” said Bhatia. The team will continue this research by testing the imaging capabilities in animal models.

Another solution, described in the Jan. 16 issue of the Proceedings of the National Academy of Sciences, is a novel “homing” nanoparticle that mimics blood platelets. Platelets flow freely in the blood and act only when needed, by keying in on injured blood vessels and accumulating there to form clots. Similarly, these new nanoparticles key in on a unique feature of tumor blood vessels.

Ruoslahti had identified that the lining of tumor vessels contains a meshwork of clotted plasma proteins not found in other tissues. He also identified a peptide that binds to this meshwork. By attaching this peptide to nanoparticles, the team created a particle that targets tumors but not other tissues. When injected into the bloodstream of mice with tumors, the peptide sticks to the tumor’s clotted mesh.