Scientists create nano-size packets of genetic code aimed at brain cancer seed cell

In a "proof of concept" study, scientists at Johns Hopkins Medicine say they have successfully delivered nano-size packets of genetic code called microRNAs to treat human brain tumors implanted in mice. The contents of the super-small containers were designed to target cancer stem cells, a kind of cellular "seed" that produces countless progeny and is a relentless barrier to ridding the brain of malignant cells. 

"Brain cancer is one of the most widely understood cancers in terms of its genetic makeup, but we have yet to develop a good treatment for it," says John Laterra, M.D., Ph.D., professor of neurology, oncology and neuroscience at the Johns Hopkins University School of Medicine and a research scientist at the Kennedy Krieger Institute. "The resilience of cancer stem cells and the blood-brain barrier are major hurdles."

Laterra and Green, who are members of the Johns Hopkins Kimmel Cancer Center, designed a way to efficiently deliver super-tiny packets of microRNAs into established brain tumors. The microRNAs target brain cancer stem cells to halt their capacity to propagate and sustain tumor growth.

The packets are made of biodegradable plastic similar to material used for surgical sutures and that degrades over time. They are 1,000 times smaller than the width of a human hair and typical of the size and shape of natural components that cells use to communicate. When cancer cells engulf the packets, they break apart and release their microRNA "payload" specifically where the microRNAs need to take action within the cancer cells.

Encased in the nanopacket are microRNAs that specifically bind to messenger RNAs linked to two genes: HMGA1 and DNMT, which function together to regulate gene expression programs in cells.