New technique targets cancer tissues

A Purdue University innovation developed for brain tumour surgery is being expanded to provide doctors with an assessment tool to preserve, analyse and remove cancer tissues.

Valentina Pirro, a cancer research scientist in Purdue’s Department of Chemistry
Valentina Pirro, a research scientist in Purdue’s Department of Chemistry

The technology was developed in the Aston Lab of Purdue’s College of Science,  which is led by Graham Cooks.

It is claimed that the team’s mass spectrometry imaging technique could determine if microscopic cancerous tissue is still present in a sample, and provide more information to influence a surgeon’s decisions regarding further tissue removal.

Team member Valentina Pirro, a research scientist in Purdue’s Department of Chemistry, said in a statement that other mass spectrometry techniques have limitations.

“Mass spectrometry can identify and measure molecules within a tissue by measuring a signal that relates to the mass and structure of the molecule. It can be used in cancer diagnostics because it’s able to monitor the differential distribution of lipids or malformed metabolites that distinguish normal and cancerous tissue,” she said. “With some form of mass spectrometry imaging, the chemicals or solvents used in the process can often destroy the tissue sample. Essentially, you have one shot at getting the data and then the sample is gone.”

Cooks and his research team have developed a morphologically friendly method for tissue imaging that can be used to perform Desorption Electrospray Ionisation Mass Spectrometry (DESI-MS).

“Our method allows researchers to choose solvent combinations that don’t affect the morphology, or form, of the tissue. This means the tissue’s native structure is preserved and after the experiment you’re able to take your tissue and stain it or use it for other experiments to retrieve complementary chemical information,” Pirro said.

“The analysis is extremely simple and straightforward because we can analyse tissue sections or smears with no sample preparation and then validate our results with standard histopathology. Essentially this solvent is used as a spray that is directed onto a small area of a sample and extracts molecules contained within.”

This assessment can be completed quickly while in the operating room, without interfering with the surgery, said Pirro.

“We were able to modify a commercial DESI-MS instrument so that it sits on top of a cart as a standalone system and can be easily wheeled in the operating room when needed. Once a surgeon resects a small biopsy, we can smear it on a glass slide and analyse it as is. After a few minutes we can tell the surgeon if the tumour is still present in the tissue sample and estimate the percentage of infiltration,” she said.

Pirro said that preoperative MRI images are typically used to help guide surgeons but they have limitations.

“Preoperative MRI images don’t always precisely translate to the area of surgery,” she said. “Additionally, there may be high infiltration of the tumour beyond what the MRI image is able to see. These limitations can cause difficulty in safely removing as much of the tumour as possible.”

The technical challenges for brain tumour surgery and treatment applications helped lead the research team to this expanded use of the technology.

“Brain tumours are specifically complicated because they infiltrate into the brain and don’t make clear borders,” Pirro said. “In order to make sure the patient has the highest chance of survival, it’s imperative that as much cancer tissue as possible is removed while trying to minimise neurological damages.”

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