July 15, 2021, NEW YORK – Researchers led by Ludwig MIT scientist Sangeeta Bhatia have devised a diagnostic nanoparticle that can both reveal the presence of tumors through a urine test and function as an imaging agent, pinpointing where the tumors are located. Their work was reported July 15 in Nature Materials.
Bhatia, who is the John and Dorothy Wilson Professor of Health Sciences and Technology and Electrical Engineering and Computer Science at MIT and a member of MIT’s Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science, has been developing cancer-detecting nanoparticles coated with peptides that are specifically cleaved by enzymes known as proteases. When the particles encounter a tumor, the peptides are snipped off by proteases expressed by cancer cells and excreted in the urine, where they are detected.
To modify the particles so they could also be used for PET imaging, Bhatia and colleagues added a radioactive tracer called copper-64. They also coated them with a peptide that is attracted to acidic environments, such as the microenvironment in tumors, to induce the particles to accumulate at tumor sites. Once they reach a tumor, these peptides insert themselves into cell membranes, creating a strong imaging signal above background noise.
The researchers tested the diagnostic particles in two mouse models of metastatic colon cancer, in which tumor cells travel to and grow in the liver or the lungs. After treatment with a chemotherapy drug commonly used to treat colon cancer, the researchers were able to use both the urine signal and the imaging agent to track how the tumors responded to treatment.
The MIT press release from which this summary is derived can be found here.