A new study published in Nature Communications reveals a new novel ‘dot’ nanosystem that dramatically improves the visualization of tumors and thereby improves cancer detection.
The study by researchers at Sanford Burnham Prebys Medical Discovery Institute (SBP) and the resulting system achieves a five-fold increase over existing tumor-specific optical imaging methods. The novel approach generates bright tumor signals by delivering “quantum dots” to cancer cells without any toxic effects.
The new method utilizes quantum dots, QDs–tiny particles that emit intense fluorescent signals when exposed to light–and an “etchant” that eliminates background signals. The QDs are delivered intravenously, and some of them leave the bloodstream and cross membranes, entering cancer cells. Fluorescent signals emitted from excess QDs that remain in the bloodstream are then made invisible by injecting the etchant.
The method was developed using mice harboring human breast, prostate and gastric tumors. QDs were actively delivered to tumors using iRGD, a tumor penetrating peptide that activates a transport pathway that drives the peptide along with bystander molecules–in this case fluorescent QDs–into cancer cells. iRGD methodology was originally developed in Ruoslahti’s lab.
To our knowledge, this is the first in vivo example of a background-destroying etchant being used to enhance the specificity of imaging,” says one of the researchers. “We are encouraged that we were able to achieve a tumor-specific contrast index (CI) between five- and ten-fold greater than the general cut-off for optical imaging, which is 2.5.”
“Moving forward we will focus on developing our novel nanosystem to work with routine imaging tests like PET scans and MRIs. In our studies with mice, we use optical imaging, which isn’t always practical for humans,” the authors explain.