By Mark Dwortzan
While the availability of antiretroviral therapy has become more widespread for HIV- positive patients in resource-limited countries, few of these patients are monitored using viral load testing to determine how their treatment is progressing. Monitoring involves periodic measurements based on analyzing RNA extracted from blood samples, a procedure that requires the kind of infrastructure that only a well-equipped, central lab can provide. But getting blood samples to the lab from remote locations can be quite expensive, as they must be kept in cold storage for the entire journey.
Now Associate Professor Catherine Klapperich (BME, MSE) and collaborators in her lab and the Fraunhofer Center for Manufacturing Innovation at Boston University have demonstrated a portable, power-free system for extracting RNA from whole blood samples and storing them on detachable cartridges for up to one week below 98.6 degrees Fahrenheit. Described in Analytical Methods and Chemistry World, the 2.5-pound device costs only about $300 to manufacture, and chemical reagents used to run the device are relatively cheap.
“By empowering healthcare workers to preserve samples without requiring refrigeration, our technology could enable more HIV-positive patients to receive ongoing monitoring,” said Klapperich.
The system is essentially a modified version of Klapperich’s System for Nucleic Acid Purification (SNAP), a sealed microfluidic system powered by a standard bicycle pump. The pump directs a bodily fluid such as blood or saliva through a channel filled with a polymer designed to adhere to selected nucleic acids. In this study Klapperich and her collaborators used a special polymer to bind to RNA in the blood and air-dried the samples to keep the RNA from degrading. Using SNAP, the entire RNA extraction process took less than 35 minutes.
A major next step is to integrate this version of SNAP with a molecular diagnostic tool to provide a single, integrated system to extract and analyze blood samples for HIV viral load monitoring. Klapperich recently demonstrated a similar SNAP-based, integrated point-of-care device that extracts and analyzes DNA to detect a common bacterium that causes infectious diarrhea.
The research was funded by PATH, a Seattle-based, international nonprofit organization that transforms global health through innovation, as part of a larger National Institutes of Health grant.