This Small Business Innovation Research (SBIR) Phase I project addresses the need for rapid, cost effective and efficient sample preparation for isolating rare cells (e.g., pathogens, circulating tumor cells, etc.) from large blood volumes. A prototype of an innovative sample preparation technology will be developed and its performance will be demonstrated during Phase I. Resonant Acoustic Cell Enrichment (RACE?) technology employs acoustophoresis to provide a continuous flow, automatable, and rapid alternative to the current methods for isolation of rare cells. RACE enables processing of large blood volumes at 10s of ml/min without adversely affecting cell viability. It allows purification of rare targets out of whole blood based on binding target cells to antibody-coated beads and concentrating the beads rapidly into a small volume of clean buffer. Using this approach, cells can be concentrated into small volumes in a preferred buffer in a fraction of time required by current technology. Thus, target cells can be isolated in minutes while the user waits. During Phase I, recovery and enrichment of bacterial markers in spiked animal blood samples will be examined with qPCR.
The broader commercial impact of the proposed technology is the potential for clinical applications. For example, sepsis is a serious medical condition that is usually treated in intensive care units. Treatment requires identification of the type of infection afflicting the blood stream. However, identification of the type of pathogen is confounded by low number of colony forming units per milliliters of blood (<10 cfu/mL). Currently, this is remedied by the rapid processing of larger volumes of blood (3-10 mL) and the use of red blood cell lysis followed by centrifugation to increase the yield of pathogenic microorganisms. Using the RACE technology, the pathogens would be isolated in a small volume of clean buffer that can be readily analyzed using genetic analysis techniques. The immediate market for the proposed sample preparation system is point-of-care DNA-based genetic testing. Acoustophoresis devices will be relatively inexpensive; a sample preparation system could be delivered to the market for $5,000 to $10,000.
Acoustic Biosystems has successfully developed, tested, and demonstrated a novel acoustophoretic sample processing technology, Resonant Acoustic Cell Enrichment (RACE™). This technology includes a flowing system comprising of lamination of particle- or cell-containing samples and a clean buffer stream at the inlet. Subsequently, acoustophoretic focusing pushes the target particles initially present in the sample across the laminar stream boundaries and into the clean buffer layer. The concentrated clean sample is then collected as the output stream. With RACE processing, target particles and cells are enriched by both concentration and washing. We show that the current RACE sample processing system allows high volume, continuous sample concentration and purification. The system developed for the Phase I effort was expressly developed for these proof-of-principle studies. We demonstrated the ability to enrich cells and particles at high sample throughputs of greater than 10 mL/min, which exceeds the proposed design goals. We found that concentrating and washing particles into a clean buffer stream provides reduction in molecular background in the sample, as well. Nearly quantitative recovery of the target particles in the concentrated outlet is shown at lower levels of concentration and the tradeoff between focal tightness, concentration, and recovery in the device is explored. Furthermore, the results of acoustic bead-based isolation and recovery of dilute E. coli in both buffer and blood is presented. The acoustic technique appears to offer near quantitative recovery of E. coli at concentrations far lower than the 200 microbes per milliliter limit reported in the literature for magnetic bead isolation techniques. These results provide the supporting testimony to the suitability of RACE for sample preparation, particularly for rare cell isolation and purification.