Gene delivery method 'hijacks' tumor blood vessels

Targeted viral vectors accumulate in a cancerous ovary's blood vessels.--Courtesy of Washington University in St. Louis

In what could become a vast improvement to the delivery of gene therapy to combat cancer, U.S. researchers have developed injectable gene-carrying viruses that could eventually stop tumor growth or make chemotherapy more effective.

Scientists at the Washington University School of Medicine in St. Louis created what they call "targetable injectable vectors," which are deactivated viruses that carry a modified gene through the blood stream directly to a tumor, where they act in the abnormal blood vessels to change the microenvironment there. The modifications aren't meant to kill the tumor by restricting blood flow, the way many therapies do, but by "hijacking" them to curb cell growth or acting as a gateway for other cancer drugs.

The team published the study, a very early proof-of-concept, in the journal PLOS ONE. They delivered a gene that caused the blood vessels only to glow green, but this proves the vectors' ability to cause any change at all in the cells. It also showed that they were able to specifically target the cells rather than surrounding healthy cells.

And while many gene therapies tend to accumulate in the liver, which can be harmful, the scientists propose a way to prevent it. They programmed the cells to "detarget" the liver and focus instead on the blood vessels.

"Most current gene therapies in humans involve taking cells out of the body, modifying them and putting them back in," lead researcher David Curiel said in a statemtent. "This limits gene therapy to conditions affecting tissues like the blood or bone marrow that can be removed, treated and returned to the patient. Today, even after 30 years of research, we can't inject a viral vector to deliver a gene and have it go to the right place."

Besides many different kinds of cancer, this therapy could have an impact on other conditions in which the blood vessels are affected, such as Alzheimer's disease, multiple sclerosis or heart failure.

- here's the Washington University in St. Louis report