Nanowire device could detect cancer with a urine test

EVs can be thought of as small 'chunks' of a cell that are able to pinch off and circulate throughout the body to deliver messenger cargo to other cells. These messengers have become increasingly recognised as crucial mediators of cell-to-cell communication.

In a new study reported in Science Advances, researchers centered at Nagoya University have developed a novel medical device that can efficiently capture these EVs, and potentially use them to screen for cancer.

"EVs are potentially useful as clinical markers. The composition of the molecules contained in an EV may provide a diagnostic signature for certain diseases," lead author Takao Yasui explains.

"The ongoing challenge for physicians in any field is to find a non-invasive diagnostic tool that allows them to monitor their patients on a regular basis--for example, a simple urine test."

Among the many molecules EVs have been found to harbor are microRNAs, which are short pieces of ribonucleic acid that play diverse roles in normal cellular biology. Critically, the presence of certain microRNAs in urine might serve as a red flag for serious conditions such as bladder and prostate cancer.

While this important cargo could therefore theoretically aid physicians in cancer diagnoses, there are still many technological hurdles that need to be overcome. One such hurdle: finding a feasible method to capture EVs in sufficient quantities to analyse them in a routine clinical setting.

"The content of EVs in urine is extremely low, at less than 0.01% of the total fluid volume. This is a major barrier to their diagnostic utility," Yasui notes. Our solution was to embed zinc oxide nanowires into a specialised polymer to create a material that we believed would be highly efficient at capturing these vesicles".

"Our findings suggest that the device is indeed quite efficient. We obtained a collection rate of over 99%, surpassing ultracentrifugation as well as other methods that are currently being used in the field."

To test the practicality of their device, the research team compared the microRNAs of EVs isolated from healthy patients with those isolated from patients who were already diagnosed with bladder, prostate, and other forms of cancer.

Notably, their technique required only 1 milliliter of urine--far more than the typical "deposit" provided during a routine checkup--and found a substantially greater number and different types of microRNAs compared with the standard ultracentrifugation approach.