NOTE: This is an overview of the entire article, which appeared on Stanford School of Medicine’s web site on August 12, 2012.
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Stanford University researchers Jennifer Cochran and Matthew Scott have created a bioengineered peptide that enables imaging of medulloblastomas in lab mice. Peptides are short chains of amino acids integral to cellular processes. The researchers altered the sequence of a cystine knot peptide, or knottin. These peptides are notable for their stability and resistance to breakdown.
Medulloblastomas are among the most devastating of malignant childhood tumors that originate in the cerebellum, or lower rear portion of the brain. More than 70% of pediatric medulloblastomas are diagnosed in children under 10. These tumors are rare in adults and children under a year old. Obtaining accurate images of medulloblastomas is critical for treatment purposes. The tumors are often treated by surgical resection in conjunction with chemotherapy and radiation, and it can be difficult to remove them while leaving healthy tissue intact due to their often indistinct margins.
According to Cochran, “These tumors can come back very aggressively if not completely removed, and their location makes cognitive impairment a possibility if healthy tissue is taken.”
Currently, MRI scans are used to locate and resect the tumors, but there are limitations. The brain can shift during an operation, so precision can be a problem.
“The new peptide represents a major advance in tumor-imaging technology”, said Melanie Hayden Gephart, MD, neurosurgery chief resident at the Stanford Brain Tumor Center and a lead author of the paper. She went on to say that the advantage of this new technique would be to illuminate the tumor in real time, seeing it directly under a microscope rather than relying on the image taken prior to surgery.
The project itself came about through a bit of serendipity. Cochran and Scott’s respective labs, at Stanford’s James H. Clark Center, were next to each other, which helped precipitate the project.
“So in a very real sense, our project wasn’t an accident”, said Scott. “In fact, it’s exactly the kind of work the Clark Center was meant to foster … it’s a form of social engineering that really works.” Work on this project is ongoing with support from The Stanford Center for Children’s Brain Tumors at Lucile Packard Children’s Hospital and from several other funding sources. The hope is to translate the new technology into patient care.