Quantum dots help cancer imaging studies

One of the more difficult diagnostic tasks an oncologist faces is determining if cancer has spread to the lymphatic system, particularly when it is necessary to assess lymphatic drainage from two separate drainage basins.

Now, using multiple quantum dots, each with a distinct color, researchers at the National Cancer Institute’s Center for Cancer Research have developed a method for accurately mapping lymphatic flow from more than one drainage basin.

In a demonstration of this new technique, a research team headed by Hisataka Kobayashi, M.D., Ph.D., used two colors of quantum dots to map lymphatic flow from the breast and upper extremities into common lymph nodes. To track the quantum dots, the investigators used two-color near infrared lymphangiography. The researchers report their findings in the journal Breast Cancer Research and Treatment.

In the course of their studies, the investigators found that proper selection of quantum dot size improved their ability to map lymphatic flow from different regions of the body. Larger quantum dots, approximately 12 nanometers in diameter, proved optimal for imaging lymphatic flow from the upper extremities, while quantum dots of approximately 6 nanometers in diameter worked best for mapping lymphatic drainage from mammary glands.

Quantum dots are also proving useful in labeling human blood cells, a finding that could help researchers answer questions about how these cells move through the body. In a paper published in the journal Leukemia Research, a team of investigators headed by H. Phillip Koeffler, M.D., and colleagues at the University of California, Los Angeles, have shown that they can label all major types of human blood cells with quantum dots. As a demonstration of the utility of this technique, the researchers then monitored dividing human blood cells.

The investigators also showed that they could label specific types of blood cells by linking the quantum dots to antibodies that recognize molecules found on those cells. As a result, the investigators were able to identify different kinds of blood cells, such as leukemic cells and normal cells, in a mixture of blood cells.

The work on mapping lymphatic flow into lymph nodes, which was supported by the National Cancer Institute, is detailed in a paper titled, “Simultaneous two-color spectral fluorescence lymphangiography with near infrared quantum dots to map two lymphatic flows from the breast and the upper extremity.” An investigator from the University of Tokyo also participated in this study. An abstract of this paper is available through PubMed. View abstract.

The work on tracking blood cell movement, which was supported by the National Cancer Institute, is detailed in a paper titled, “Quantum dot labeling and tracking of human leukemic, bone marrow and cord blood cells.” Investigators from the University of California at Davis and the University of Southern California also participated in this study. An abstract of this paper is available through PubMed. View abstract.