Lighting The Way Through Brain Surgery
By Merry Morris
Medulloblastoma. Anaplastic astrocytoma. Mixed glioma. Brain tumor. Regardless of the name, the diagnosis is terrifying to receive and a surgical challenge to treat.
As anyone who has seen a classroom dissection can tell you, structures that look well defined in textbook diagrams can be hard to discern in an actual organism. No dotted lines show you where to cut.
Brain surgeons face a similar, but much more daunting task. They must completely remove the tumor and only the tumor, without being able to see it clearly. While MRI scans are a tremendous tool for surgeons, images don’t necessarily correspond to the surgical view. To distinguish healthy tissue from cancerous, surgeons must often rely on sight and touch.
Surgical removal of tumors is not always perfect. Latrogenic injuries, those resulting from medical treatment, can result when vital tissues are damaged inadvertently. Short-term memory loss, motor difficulties, vision problems and other conditions can occur without medical errors. In some procedures, just getting to the tumor can be devastating to the patient.
Staying Within The Lines?
There will never be a “dotted line” for surgeons to follow to remove cancerous tissues, but an innovative product — Tumor Paint — developed by Dr. Jim Olson, a pediatric oncologist, and his colleagues at Fred Hutchinson Medical Center in Seattle, aims to improve surgeons’ chances of success. When injected into a patient’s vein, Tumor Paint travels to the brain, passes through the blood-brain barrier and binds to and enters into malignant cells.
Viewed under near-infrared light, the “painted” cells literally glow, in theory allowing surgeons to see malignant tumor borders for more precise removal with less damage to nonmalignant tissue. The molecule responsible for this high-resolution tumor visualization is a combination of a protein chlorotoxin (from the deathstalker scorpion!) and a fluorescent dye, chosen for its emission in the near-IR range. Initial applications of the process revealed glowing tumor cells, just as predicted. After encouraging results in dogs, researchers won approval to continue Tumor Paint testing on human subjects.
Obtaining all approvals for Tumor Paint and getting it into widespread use is a complicated and lengthy process. Studies must verify that the paint can reach various tumor types, surgeons have improved surgical results and patients experience better outcomes. Researchers have passed commercial development of Tumor Paint to Blaze Bioscience, which has taken the compound through preclinical and into Phase One trials
- Review the structures of the human brain. Which functions are associated with those structures?
- Investigate fluorescence. What happens on the molecular level when a material fluoresces?
- What is the blood-brain barrier? How does it protect the brain? How does it interfere with drug treatments?