April 6, 2012 | by City of Hope Staff
One of the biggest challenges to treating diseases in the brain is inside the brain itself. There’s a protective barrier between the brain and its blood supply that can keep medicine from getting to brain tissue.
City of Hope scientists are studying ways to sneak through this so-called “blood-brain barrier.” Bihong Beth Chen, M.D., Ph.D., clinical assistant professor in the Department of Diagnostic Radiology, and her colleagues recently became the first researchers to measure how changes in the barrier affect how much of a medication actually reaches brain cells — and they did it while cancer patients were being treated. It’s important because it could eventually help doctors pick the most effective schedules for giving patients drugs.
The study was part of a larger, one-of-a-kind City of Hope clinical trial using special stem cells to treat lethal brain tumors.
After patients underwent surgery to remove cancer tissue, their surgeon injected these stem cells into the brain. Four days later, the patients received an inactive chemical that speeds through the blood toward the brain, where the waiting stem cells turn that chemical into a cancer-killing drug.
To get to the stem cells, though, the substance has to jump across the blood-brain barrier. And that’s where imaging comes in.
The researchers used a type of magnetic resonance imaging, or MRI, technology to see into the brain and watch on a screen as a special dye flowed from the blood into brain tissue. They measured how the flow changed over the next few days, and found that the blood-brain barrier was most open about five days after the procedure.
Besides giving the scientists insight into when to best give patients the inactive chemical in the study, the results give researchers a starting point for helping to guide drug timing for patients with other kinds of cancer.