New laser system helps determine cancer aggressiveness, leading to better treatments

10/12/2016 - 2:31pm

When we get cancer, our bodies betray us.

In about 80 to 90 percent of all types of human cancers (excluding those caused by viruses), seemingly normal cells mutate and turn into cancer cells, which spread and can develop into tumors. It is a process researchers have long been studying to help understand cancer behavior and develop more effective, tolerable treatments.

When a cancerous tumor is discovered, primary treatment options are surgery, chemotherapy and radiation. It is difficult to determine how aggressive the treatment needs to be to match the aggressiveness of the cancer, so patients might be deliberately over-treated to ensure that as many of the cancer cells are eradicated as possible.

But that “everything-but-the-kitchen-sink” approach may soon change. A team of researchers at the University of Illinois at Urbana-Champaign, working with Carle Health System physicians in Urbana, Ill., has developed a new way of imaging and analyzing cancerous tumors from breast cancer patients that can help determine the aggressiveness of the cancer, which could aid in designing targeted individualized treatment for the greatest possible efficacy.

Stephen Boppart is leading the research team that developed a groundbreaking new portable, programmable, pulsating laser system recently tested on cancerous tumor tissue in the operating room during breast cancer surgery. Boppart is a professor of Bioengineering, Electrical and Computer Engineering, and Medicine and director of the Biophotonics Imaging Lab and the Center for Optical Molecular Imaging at the Beckman Institute of Advanced Science and Technology at Illinois. Advantages offered by the breakthrough technology include:

  • Stain-free imaging — bathing the tissue sample in light instead of chemical stains, which allows the sample to remain intact for further testing and study
  • Immediate examination of the tissue — during surgery in the OR — and immediate results, with images reviewable in seconds instead of days or weeks. (When tissue is stained, it usually takes at least 24 hours to view results with a microscope.)
  • A more comprehensive picture that supplies more refined information than previously available, including a better understanding of the role of microvesicles.

Label-free multimodal optical imaging of local tumor invasion along a tumor margin. Label-free images from fresh mammary tissue (top row) are compared to standard stained histology images (bottom row). A wealth of structural, molecular, metabolic and functional information can be visualized rapidly in real time without the use of stains or labels, helping to elucidate the mechanisms in carcinogenesis and offering the potential for new diagnostic and prognostic biomarkers of cancer.
Label-free multimodal optical imaging of local tumor invasion along a tumor margin. Label-free images from fresh mammary tissue (top row) are compared to standard stained histology images (bottom row). A wealth of structural, molecular, metabolic and functional information can be visualized rapidly in real time without the use of stains or labels, helping to elucidate the mechanisms in carcinogenesis and offering the potential for new diagnostic and prognostic biomarkers of cancer.

The new research has been underway for more than three years, and it includes the development and construction of the laser technology and system and its use in human studies and pre-clinical trials — the latter showing the carcinogenesis over time and correlated with the human studies. The work is novel and complex enough that it resulted in not one but four related papers, the first of which was recently published in Nature Photonics.

"The basis of the new technology is “multimodal, multiphoton imaging,” explained Sixian You, a Ph.D. student in Bioengineering who is a member of Boppart’s team and a co-author on the paper. Multimodal imaging is a combination of two or more imaging techniques, and the team’s approach simultaneously targets chemical, functional and structural 3D imaging to gain a more comprehensive picture of the cancer cells and their microenvironment. Multiphoton is the simultaneous use of more than one photon in strong, fast laser pulses.

Boppart said that the system also generates a unique type of light, which allows medical personnel to gain a better, deeper understanding of how the cancer cells spread. “The key to this work is the laser source,” he said.

The researchers started with several large benchtop lasers and then began to develop enhancements to the system, because the lasers are expensive and so big and heavy that they cannot be wheeled into an operating room. What resulted is a system that evolved beyond the benchtop, and the paper is focused on how the team moved the system to optical fibers, then filtered the light, and turned the force of a big powerful laser into something more affordable and portable, yet still effective.

Development of the new laser technology is led by Haohua Tu, Ph.D., an optical research scientist at the Beckman Institute who is first author on the paper.

The team is constantly refining the portable system, Boppart said, in an attempt to be able to consistently and accurately predict the aggressiveness of each patient’s cancer.

On a Monday morning in mid-July, You spent several hours in the operating room at Carle Hospital during breast cancer surgery, where the team used the new imaging system in the OR to immediateexamine the latest excised cancer tumor to which they had been granted access.

In addition to examining cancerous tissue from several patients, the team also has been able to look at seemingly normal tissue from the same breast and tissue from breast reduction surgery (the latter in patients with no history or diagnosis of cancer), Boppart said, in attempts to understand more about cancer’s aggressiveness.

In previous work, another Boppart lab team developed a probe used during surgery to detect the structural margins of a cancerous tumor, work that helped inform the new laser system research. Although a surgeon can remove a tumor known to be cancerous and some of the surrounding tissue that might also be mutating into cancer cells or contain metastatic cancer cells, Boppart said, there is no way to determine with great accuracy and immediacy which cells are normal and which are not. So one of the questions the team began exploring is, “Do we need to start defining molecular margins instead of structural ones?” Boppart said.

Traditionally, physicians have used the naked eye or frozen sections to determine the pervasiveness of the cancer during surgery, but these options often result in high error rates. And, although Optical Coherence Tomography (OCT) imaging has been used in the OR for years, it only provides structural information about the cancer cells.

The new imaging system has achieved highly accurate, useful, molecular-level results showing how aggressive the cancer is by analyzing the chemistry and function of cancer cells, in addition to their structure, with analyses confirmed by traditional laboratory pathology.

During the team’s development of the laser and using it in pre-clinical trials and in the operating room, the researchers have advanced the understanding of the role of microvesicles (also known as exosomes) in the aggressiveness of cancer and their use as biomarkers. Exosomes are fragments from a cell that are cast off and help to facilitate communication between cells.

“Three years ago, the (laser) system was barely working,” You said. “One day we got an image from fresh human breast cancer tissue, and we were all just amazed at the incredibly rich information revealed by our imaging system.” That’s when the team first started to see the exosomes and began examining existing literature to understand what was going on, You added.

In the microenvironment, the research team identified and examined different kinds of exosomes, each with its own optical signature, and each containing different materials that can portend the existence of cancer.

“We can now visualize how the tumor cells send out these exosomes, and how these exosomes pre-condition normal cells and prepare the microenvironment for the metastasizing tumor cells that would follow,” Boppart said. And an abundance of the exosomes is an indicator of an aggressive tumor.

Boppart’s team has seen these exosomes immediately in vivo and observed how they move around via the spatial information gathered from the new laser technology and imaging system.

The researchers are adding to the body of knowledge on exosomes and their role in cancer — a topic mainly identified and studied during the last 10 years. And their new imaging technology is revealing details that contribute to a better understanding of tumor content and cell behavior — information that drives treatment options.

“Right now, we know a lot about how the tumors send the message (to create more cancer cells) in the microenvironment, the macroenvironment, and around the body,” said Marina Marjanovic, Ph.D., associate director of the Center for Optical Molecular Imaging, member of the Bioengineering teaching faculty, and project coordinator for Boppart’s research group. “But the therapy is still really hit or miss. … And no one has previously identified the proteins and lipids found in the exosomes in tumors,” she added.

The researchers not only have achieved startling results when comparing their assessments to histology reports — the lab reports that have been the “gold standard” of cancer tests for decades — they also have been able to gather much more information about the exosomes’ role in causing normal cells to welcome cancer cells as they spread and prepare the tissue for the tumor to grow.

To conduct a study with this significance and that has the ultimate goal of helping patients requires tissue from humans.

“It takes everyone to do these challenging complex projects, and our environment here (at Illinois) has allowed us to do this,” Boppart said. “It’s a great example of how engineers working with physicians can make a big impact.”

It is also fortunate that Boppart is both a medical doctor and a researcher. He earned master’s and bachelor’s degrees in Electrical Engineering (his B.S. with an option in Bioengineering) from Illinois, a Ph.D. in Medical and Electrical Engineering from the Massachusetts Institute of Technology, and an M.D. from Harvard Medical School. He completed his residency training in Internal Medicine at Carle and the University of Illinois at Urbana-Champaign College of Medicine. So he is able to bridge both the research and medicine sides of the work. And he appreciates the value of patients who volunteer to help advance the study.

“In general, we’ve had people very willing to participate,” Boppart said. “These are cancer patients who are under tremendous stress. For patients who often feel a bit helpless, this is a chance to help others.”

Now the team is preparing to share their findings in the three related papers — one of which was just published in September. The published studies detail what they have learned about the exosomes and their role as biomarkers, and knowledge gained in the pre-clinical longitudinal studies and correlated human studies.

As this work provides new indicators of a cancer’s aggressiveness and its likely response to customized, targeted treatment, it reveals more information than ever before about the inner workings of human cancer. And soon that may allow all of us to see cancer as less of a mysterious betrayal of our cells and more as a manageable disease.

The paper, "Stain-free histopathology by programmable supercontinuum pulses," published in Nature Photonics

Related paper, "Raman Spectroscopic Analysis Reveals Abnormal Fatty Acid Composition in Tumor Micro- and Macroenvironments in Human Breast and Rat Mammary Cancer," published in Scientific Reports