Tumors deep inside the body can be very difficult to spot, track, and study. The brain, being surrounded by a thick skull, is particularly challenging to image using light, so MRI and CT are currently the go-to imaging modalities when looking at deeply seated tissues.
Now, researchers at Stanford University are reporting the development of new nanoparticles that can be used to light up and image tumors located well below the surface of the skin. The nanoparticles should be useful for not only diagnosing and monitoring tumor progression, but also for predicting how individual patients will respond to a given immunotherapy.
The new nanoparticles are based on erbium, a rare-earth element that glows in the infrared. They have a special coating that allows antibodies, that can bind to specific cancer cells, to be attached. Additionally, the same coating reduces the toxicity of the nanoparticles, allows them to dissolve in the blood stream, and helps them exit the body.
When low energy light illuminates the new nanoparticles, they glow brightly with infrared light. Using targeted antibodies to make sure the nanoparticles attach only to specific cancer cells allows the nanoparticles to only illuminate those cells.
To show off their technology, the Stanford team used the nanoparticles to illuminate the inside of living mouse brains to reveal tumors within that are susceptible to anti-cancer medications. This was achieved by attaching an antibody to the nanoparticles that targets a specific protein that makes cells susceptible to the anti-cancer meds in question.
The researchers used their new technique along with near-infrared-IIb, another imaging modality, to see cancer cells and T-cells at the same time. This allowed them to see how the immune system gathers its forces from the rest of the body to attack a brain tumor in real time.
It is hoped that the new technology will help clinicians to find, target, and track tumors non-invasively, but also perhaps act as a way for surgeons to visualize cancerous tissues during resections.
Here’s a video of a live mouse brain imaged using the new technique:
Study in Nature Biotechnology: In vivo molecular imaging for immunotherapy using ultra-bright near-infrared-IIb rare-earth nanoparticles