A nanowire device has been developed that will facilitate the efficient collection of extracellular vesicles (EVs) from urine and enable the extraction and analysis of miRNA. According to a research team from Nagoya University this novel device makes simple and noninvasive miRNA-based diagnostics possible.
"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 of the Science Advances paper Takao Yasui explains. "The ongoing challenge for physicians in any field is to find a noninvasive 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. 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 analyze 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 specialized 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. "Finding a specific, reproducible marker to help confirm a cancer diagnosis is difficult. This is especially true for microRNAs, which are a relatively new class of markers in the field," co-author Yoshinobu Baba explains. "Sometimes finding just one reliable microRNA is considered a success. Using this approach, we were surprised to find that not just one, but whole combinations of microRNAs might be associated with different types of cancers. The findings are preliminary, of course, but we hope our device can help to lay the groundwork for easier ways to diagnose life-threatening diseases as early as possible."
Image: Nanowire extraction allowed many microRNAs to be compared at once using urine samples collected from patients. Expression of each microRNA is shown as low/downregulated (blue), intermediate (black), or high/upregulated (yellow). The analysis reveals unique patterns of expression for groups of microRNAs when comparing healthy donors (-) with cancer patients (+). Image courtesy of Takao Yasui.