Abstract 1461: Two dimensional acoustic wave technology offers improved label free prostate cancer cell separation in blood.
Authors: Magnusson Cecilia , Augustsson Per , Laurell Thomas , Lilja Hans 
Published: August 2014

There is an unmet need for disease biomarkers that reliably predict clinical benefit in tumor recurrence in general and in castration resistant prostate cancer (CRPC) specifically. Isolation of rare circulating tumor cells (CTCs) has emerged as an increasingly important non-invasive tool in the pursuit for better-targeted therapies for patients with disseminating tumors.

We exploit ultrasound standing wave technology in a microchip setting, and have developed a third generation acoustophoretic microchip, which in time will allow isolation of CTCs from liquid biopsies from patients with advanced stages of prostate cancer. The separation device is a silicon/glass microchannel with trifurcation inlet and outlet, an incorporated pre-alignment channel and with temperature-stabilization. The novel system is now adapted to permit processing of sample volumes corresponding to clinical samples. A pressure driven system has been incorporated and runs the separation process. It mediates fewer fluctuations, generating even more stable separation results than previous setup,

Previously acoustic separation has been performed with WBCs diluted 1:10. However in this third generation setup it is possible to use samples of undiluted WBCs and there are indications that even concentrated WBC samples might generate similar results with maintained cancer cell recovery and separation performance. Larger sample volumes have allowed us to use lower amounts of spiked cancer cells and we can easily detect concentrations of less than 1000 spiked cancer cells per mL blood. This new setup generates acoustic separation with prostate cancer cell recoveries around 95% with 0,1% WBC contamination when processed at a flow rate of 100 μl/min.

It is possible to process both PFA fixed and non-fixed cells in the microchip. The acoustic separation method is gentle and does not affect cell viability, cell proliferation, androgen receptor function or PSA secretion. It is therefore an interesting alternative to current available techniques that require cell fixation. In addition we found that dead prostate cancer cells display different acoustic properties than viable cells, which makes it possible to distinguish live from dead cancer cells by acoustophoresis. This opens up for subsequent cell analysis requiring viable cells. New progressive techniques are needed to find and identify CTC populations independent on labeled cell-discrimination capacity, such as EpCAM negative CTCs. Acoustophoresis allows recovery of cancer cells independent of antigen expression, which allows for separation of novel EpCAM negative populations of CTCs with subsequent PCR analysis. It is therefore a promising method for future non-invasive molecular interrogation of metastatic cancers.

Citation Format: Cecilia Magnusson, Per Augustsson, Thomas Laurell, Hans Lilja. Two dimensional acoustic wave technology offers improved label free prostate cancer cell separation in blood. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1461. doi:10.1158/1538-7445.AM2013-1461