Using tiny particles designed to target cancer-fighting immune cells, Johns Hopkins researchers have trained the immune systems of mice to fight melanoma, a deadly skin cancer. The experiments, described on the website of ACS Nano on February 24, represent a significant step toward using nanoparticles and magnetism to treat a variety of conditions, the researchers say.
"Size was key to this experiment," says Jonathan Schneck, M.D., Ph.D., a professor of pathology, medicine and oncology at the Johns Hopkins University School of Medicine's Institute for Cell Engineering. "By using small enough particles, we could, for the first time, see a key difference in cancer-fighting cells, and we harnessed that knowledge to enhance the immune attack on cancer."
Schneck's team has pioneered the development of artificial white blood cells, so-called artificial antigen-presenting cells (aAPCs), which show promise in training animals' immune systems to fight diseases such as cancer. To do that, the aAPCs must interact with immune cells known as naive T cells that are already present in the body, awaiting instructions about which specific invader they will battle. The aAPCs bind to specialized receptors on the T cells' surfaces and "presenting" them with distinctive proteins called antigens. This process activates the T cells, programming them to battle a specific threat such as a virus, bacteria or tumor, as well as to make more T cells.
The team had been working with microscale particles, which are about one-hundredth of a millimeter across. But, says Schneck, aAPCs of that size are still too large to get into some areas of a body and may even cause tissue damage because of their relatively large size. In addition, the microscale particles bound equally well to naive T cells and others, so the team began to explore using much smaller nanoscale aAPCs. Since size and shape are central to how aAPCs interact with T cells, Karlo Perica, a graduate
|Contact: Shawna Williams|
Johns Hopkins Medicine