New Laser-Based Tool Could Dramatically Improve the Accuracy of Brain Tumor Surgery

A new laser-based technology may make brain tumor surgery much more accurate, allowing surgeons to tell cancer tissue from normal brain at the microscopic level while they are operating, and avoid leaving behind cells that could spawn a new tumor.

In a new paper, featured on the cover of the journal Science Translational Medicine, a team of University of Michigan Medical School and Harvard University researchers describes how the technique allows them to "see" the tiniest areas of tumor cells in brain tissue.

They used this technique to distinguish tumor from healthy tissue in the brains of living mice -- and then showed that the same was possible in tissue removed from a patient with glioblastoma multiforme, one of the most deadly brain tumors.

Now, the team is working to develop the approach, called SRS microscopy, for use during an operation to guide them in removing tissue, and test it in a clinical trial at U-M. The work was funded by the National Institutes of Health.

A need for improvement in tumor removal

On average, patients diagnosed with glioblastoma multiforme live only 18 months after diagnosis. Surgery is one of the most effective treatments for such tumors, but less than a quarter of patients' operations achieve the best possible results, according to a study published last fall in the Journal of Neurosurgery.

"Though brain tumor surgery has advanced in many ways, survival for many patients is still poor, in part because surgeons can't be sure that they've removed all tumor tissue before the operation is over," says co-lead author Daniel Orringer, M.D., a lecturer in the U-M Department of Neurosurgery who has worked with the Harvard team since a chance meeting with a team member during his U-M residency.

"We need better tools for visualizing tumor during surgery, and SRS microscopy is highly promising," he continues. "With SRS we can see something that's invisible through conventional surgical microscopy."

The SRS in the technique's name stands for stimulated Raman scattering. Named for C.V. Raman, one of the Indian scientists who co-discovered the effect and shared a 1930 Nobel Prize in physics for it, Raman scattering involves allows researchers to measure the unique chemical signature of materials.

In the SRS technique, they can detect a weak light signal that comes out of a material after it's hit with light from a non-invasive laser. By carefully analyzing the spectrum of colors in the light signal, the researchers can tell a lot about the chemical makeup of the sample.

Over the past 15 years, Sunney Xie, Ph.D., of the Department of Chemistry and Chemical Biology at Harvard University -- the senior author of the new paper -- has advanced the technique for high-speed chemical imaging. By amplifying the weak Raman signal by more than 10,000 times, it is now possible to make multicolor SRS images of living tissue or other materials. The team can even make 30 new images every second -- the rate needed to create videos of the tissue in real time.

Seeing the brain's microscopic architecture

A multidisciplinary team of chemists, neurosurgeons, pathologists and others worked to develop and test the tool. The new paper is the first time SRS microscopy has been used in a living organism to see the "margin" of a tumor -- the boundary area where tumor cells infiltrate among normal cells. That's the hardest area for a surgeon to operate -- especially when a tumor has invaded a region with an important function.

As the images in the paper show, the technique can distinguish brain tumor from normal tissue with remarkable accuracy, by detecting the difference between the signal given off by the dense cellular structure of tumor tissue, and the normal healthy grey and white matter.

The authors suggest that SRS microscopy may be as accurate for detecting tumor as the approach currently used in brain tumor diagnosis -- called H&E staining.

The paper contains data from a test that pitted H&E staining directly against SRS microscopy. Three surgical pathologists, trained in studying brain tissue and spotting tumor cells, had nearly the same level of accuracy no matter which images they studied. But unlike H&E staining, SRS microscopy can be done in real time, and without dyeing, removing or processing the tissue.

Next steps: A smaller laser, a clinical trial

The current SRS microscopy system is not yet small or stable enough to use in an operating room. The team is collaborating with a start-up company formed by members of Xie's group, called Invenio Imaging Inc., which is developing a laser to perform SRS through inexpensive fiber-optic components. The team is also working with AdvancedMEMS Inc. to reduce the size of the probe that makes the images possible.

A validation study, to examine tissue removed from consenting U-M brain tumor patients, may begin as soon as next year.

Biologists Uncover Surprising Connection Between Breast Cancer Cells and Surrounding Tissue

 Rensselaer Polytechnic Institute Biologist Lee Ligon has found a previously unknown connection between breast cancer tumor cells and the surrounding healthy tissue. The results provide new information on the earliest stages of breast cancer metastasis.

The results were published March 7, 2012, in the journal ,PLoS One. Ligon was joined in the research by Rensselaer doctoral student Maria Apostolopoulou. The research was funded by the American Cancer Society.

The research shows that a specialized type of molecule called Cadherin-23 can be found in and around breast cancer tumors. The molecule, which had never been associated with breast tissue or cancer, helps connect cancerous tumor cells to its neighboring healthy tissue, called the stroma.

"Something happens once cancerous cells enter the stroma and the cancer can very quickly become invasive," Ligon said. "Pathologists studying cancerous tissues have often noted that tumor cells make contact with the cells in the stroma, but they assumed the connections were unimportant."

Ligon and her team sought to uncover exactly what molecules were involved in attaching the tumor cells to the surrounding tissue to determine if those initial points of contact play a role in the progression of cancer through the body.

In the human breast, tumors most often originate in what are known as epithelial tissues. These tissues are made up of a specialized type of cell called epithelial cells. Epithelial cells line the interior of many structures and organs within the human body. In the breast, they line the interior of milk ducts. When epithelial cells start to divide uncontrollably, they eventually break out of the duct and literally spill into the surround tissue or stroma. The stroma is composed of cells called fibroblasts and extracellular material such as collagen fibers. In many cases, the invading cancerous epithelial cells will glom onto nearby fibroblasts in the stroma.

Ligon and Apostolopoulou worked to pick apart how the epithelial cells attached themselves to the fibroblasts. One of the primary tools the body uses to glue cells together is a family of molecules called cadherins. In the human genome there are over 80 different cadherin family members. In most cases, cadherins stick two cells of the same type together. In the case of the breast cancer tumor cells and fibroblasts, two very different cells were sticking together. Ligon sought to determine which cadherins were involved in this odd interaction.

At first, their findings were not surprising. They found cadherins associated with epithelial cells as well as cadherins associated with fibroblasts. It was the discovery of the highly specialized and unusual cadherin, Cadherin-23, that really surprised them, according to Ligon.

"Cadherin-23 has never before been associated with cancer," Ligon said. "In fact, it has previously only been shown in the sophisticated inner workings of the ear and retina."

It is still largely unknown what happens once the cells have made a connection, but the appearance of Cadherin-23 in elevated levels in cancerous tissues suggests that it might play a real role in the earliest stages of metastasis, according to Ligon. Cadherin-23 is a new and potentially very important new component in the progression of cancer for scientists to investigate, she said.

Uncovering Cancer's Inner Workings by Capturing Live Images of Growing Tumors

Scientists seeking new ways to fight cancer often try to understand the subtle, often invisible, changes to DNA, proteins, cells, and tissue that alter the body's normal biology and cause disease. Now, to aid in that fight, a team of researchers has developed a sophisticated new optical imaging tool that enables scientists to look deep within tumors and uncover their inner workings. In experiments that will be described at Frontiers in Optics (FiO), The Optical Society's (OSA) Annual Meeting, Dai Fukumura and his colleagues will present new optical imaging techniques to track the movement of molecules, cells, and fluids within tumors; examine abnormalities in the blood vessel network inside them; and observe how the tumors were affected by treatments.

These techniques, created by Fukumura and his long-term collaborators at Massachusetts General Hospital and Harvard Medical School, combine two different high-tech optical imaging methods that were custom-built for the research. One is called multiphoton laser-scanning microscopy (MPLSM), which is an advanced fluorescence imaging technology that is now commercially available at the high end of the microscope market. The other is called optical frequency domain imaging (OFDI), which images tissues by their light scattering properties. According to Fukumura, OFDI is gaining popularity in the optical imaging field but has yet to become commercially available.

"MPLSM overcomes many of the limitations from which conventional microscopy and confocal microscopy suffer, and OFDI provides robust large volume imaging data," Fukumura said.

Fukumura will present their research at FiO 2013, taking place Oct. 6-10 in Orlando, Fla. There, he will describe how his unique technique can image tumors inside and out, and show detailed pictures of live tumors -- images that he and colleagues call "astonishing."

He added that while the new combined approach would be too expensive to be used for routine diagnostic purposes, it promises to help researchers better understand the intricate workings of human cancer and aid in drug discovery to treat cancer. "These optical imaging approaches can provide unprecedented insights in the biology and mechanisms of cancer," he said.