Abstract C39: Label-free prostate cancer cell enrichment in blood using microfluidic acoustic wave technology
Authors: Magnusson Cecilia , Augustsson Per , Laurell Thomas , Lilja Hans 
Published: May 2013

Background: 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. In the present study we aimed to exploit ultrasound standing wave technology in a microchip setting, (acoustophoresis), to separate spiked epithelial prostate tumor cells in blood samples. Acoustophoresis is a non-contact and label free separation technique, which enriches cancer cells independent of EpCAM and other antigen expressions.

Methods: The separation device is a silicon/glass microfluidic channel with trifurcation inlets and outlets. A piezoceramic actuates the separation channel at λ/2 resonance, creating a force on suspended cells directed towards the center of the channel.

To achieve sufficiently high selectivity, we have developed a temperature stabilized acoustophoresis microchannel into which we have incorporated a novel cell pre-alignment channel, which orders the cells before entering an acoustophoresis cell separation channel. The pre-alignment provides vastly improved separation performance as compared to conventional acoustophoresis. Prostate cancer cell lines (DU145, LNCaP and PC3) spiked in red blood cell lysed blood were processed in the acoustophoresis chip.

Results: To demonstrate the resolution of the device for separation based on intrinsic acoustophysical properties and mobility, a population of polystyrene microspheres of non-overlapping sizes 5 and 7 μm in diameter was dissected into two fractions that each displayed 99% purity. Bead data allow for calibration of the system to achieve stable and repeatable cell separation.

Three different prostate cancer cell lines were used as a model system to address the expected diversity of CTCs in the peripheral blood of metastatic prostate cancer patients. At present the acoustic separation with pre-alignment allows cancer cell recovery up to 97% (±1.0), with a sample cancer cell purity of 98% (±0.25) for PFA fixed cells. Higher recovery rates are achievable but at the expense of lower sample purities. For non-fixed cells recovery was 84% (±3.2) when the cancer cell purity in the collected sample was 93% (±2.7). The acoustic separation method is innoxious 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.

Conclusion: Acoustophoresis with cell pre-alignment allows for recovery of cancer cells independent of antigen expression. Enrichment of cancer cells in blood with acoustophoresis is a promising method for future non-invasive molecular interrogation of metastatic cancers.

Citation Format: Cecilia Magnusson, Per Augustsson, Thomas Laurell, Hans Lilja. Label-free prostate cancer cell enrichment in blood using microfluidic acoustic wave technology [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr C39.