Generic view of front entrance to Imperial College London

Twin chemical signals direct MRI enhancers to tumours

Researchers at Imperial College London have used two common characteristics of cancer cells to help nanoparticles home in on them and, if developed successfully for medical use, show-up tumours much more clearly on MRI scans than is currently possible.

Over the past decade, medical researchers have focused their attention on magnetic nanoparticles as a way of improving their ability to find tumours in their early stages using MRI, coating them with chemical agents to latch onto cancer cells based on the chemicals and enzymes they tend to overproduce compared to healthy cells.

“Some doctors feel that even though MRI scanners are effective at spotting large tumours, they are perhaps not as good at detecting smaller tumours in the early stages,” said team leader Professor Nicholas Long of Imperial’s Faculty of Natural Sciences, department of chemistry. “We would like to improve the design to make it even easier for doctors to spot a tumour and for surgeons to then operate on it.”

The Imperial team used two cancer characteristics. One allows nanoparticles to attach to the cancerous cells. The second, an enzyme normally used to help heal wounds but which tumours often produce in large amounts, exposes a chemical coating that allows the nanoparticles to begin self-assembly.

“The innovation of our work is the combination of all these pieces to create a probe that not only localises and accumulates in the tumours, but it also responds to it changing its nature,” explained Juan Gallo of the department of surgery and cancer at Imperial.

Tested in a saline solution meant to resemble normal body conditions, the self-assembled particles improved the magnetic signal by 160 per cent.

A key issue with iron-oxide nanoparticles is their toxicity if they grow too big. According to the Imperial team, the nanoparticles grew to no more than 800nm, which is within current safe limits, said the team.

“We’re now looking at fine-tuning the size of the final nanoparticle so that it is even smaller but still gives an enhanced MRI image,” Gallo added.

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