Antigen-Laden Disks Marshal T Cells

The research - which ridded 90 percent of mice of an aggressive form of melanoma that would usually kill the rodents within 25 days - represents the most effective demonstration to date of a cancer vaccine.

"Our immune systems work by recognizing and attacking foreign invaders, allowing most cancer cells - which originate inside the body - to escape detection," explains David J. Mooney, Gordon McKay Professor of Bioengineering in Harvard's School of Engineering and Applied Sciences. "This technique, which redirects the immune system from inside the body, appears to be easier and more effective than other approaches to cancer vaccination."

The implants developed by Mooney and colleagues are slender disks measuring 8.5 millimeters across. Made of an FDA-approved biodegradable polymer, they can be inserted subcutaneously, much like the implantable contraceptives that can be placed in a woman's arm.

The disks are 90 percent air, making them highly permeable to immune cells. They release cytokines, powerful attractants of immune-system messengers called dendritic cells.

These cells enter an implant's pores, where they are exposed to antigens specific to the type of tumor being targeted. The dendritic cells then report to nearby lymph nodes, where they activate the immune system's T cells to hunt down and kill tumor cells throughout the body.

"Much as an immune response to a bacterium or virus generates long-term resistance to that particular strain, we anticipate our materials will generate permanent and body-wide resistance against cancerous cells, providing durable protection against relapse", says Mooney.

The implants could also be loaded with bacterial or viral antigens to safeguard against an array of infectious diseases. They could even redirect the immune system to combat autoimmune diseases such as type 1 diabetes, which occurs when immune cells attack insulin-producing pancreatic cells.; Source: Harvard University