Stimulating polymer

A stimuli-sensitive polymer with unique gelling properties has been developed by a team at the Department of Energy's Pacific Northwest National Laboratory, in Richland, WA. The material changes from liquid to gel in response to an external stimulus, such as an increase in temperature and is being investigated as a drug delivery agent for treating tumors.

Senior research scientist at PNNL Anna Gutowska and her team believe one of the most promising therapeutic applications of the gel is the targeted delivery of medical isotopes or chemotherapy drugs to treat inoperable solid tumors, such as those of the liver, pancreas, brain, breast and prostate. In treating early-stage prostate cancer, for example, the polymer solution would be mixed with a medicinal agent and injected directly into the tumor where body heat would cause instant gelling, which holds the therapeutic agent at the target site rather than allowing it to diffuse out.

The advantage of maintaining therapeutic levels of a drug within the tumor are obvious but also mean that a uniform dose will be safely delivered to cancer cells while minimizing damage to surrounding healthy tissue.

The polymer may also have applications as a biodegradable scaffolding to assist tissue repair in injured joints. PNNL is collaborating with the Medical University of South Carolina to test the polymer as a support for articular cartilage repair. Articular cartilage is the cushioning material that protects the ends of bones at a joint but is prone to damage and if left to its own devices will generally not self repair leading to an estimated million cartilage repair operations each year.

A new means of culturing cartilage cells, chondrocytes, together with a biodegradable version of the polymer is being developed in the lab by Gutowska that can be injected into the defect to serve as a temporary synthetic "scaffold" to support growth of the injected chondrocytes. Tests are now underway in South Carolina.