High-purity and label-free isolation of circulating tumor cells (CTCs) in a microfluidic platform by using optically-induced-dielectrophoretic (ODEP) force

Abstract

Negative selection-based circulating tumor cell (CTC) isolation is believed valuable to harvest more native, and in particular all possible CTCs without biases relevant to the properties of surface antigens on the CTCs. Under such a cell isolation strategy, however, the CTC purity is normally compromised. To address this issue, this study reports the integration of optically-induced-dielectrophoretic (ODEP) force-based cell manipulation, and a laminar flow regime in a microfluidic platform for the isolation of untreated, and highly pure CTCs after conventional negative selection-based CTC isolation. In the design, six sections of moving light-bar screens were continuously and simultaneously exerted in two parallel laminar flows to concurrently separate the cancer cells from the leukocytes based on their size difference and electric properties. The separated cell populations were further partitioned, delivered, and collected through the two flows. With this approach, the cancer cells can be isolated in a continuous, effective, and efficient manner. In this study, the operating conditions of ODEP for the manipulation of prostate cancer (PC-3) and human oral cancer (OEC-M1) cells, and leukocytes with minor cell aggregation phenomenon were first characterized. Moreover, performances of the proposed method for the isolation of cancer cells were experimentally investigated. The results showed that the presented CTC isolation scheme was able to isolate PC-3 cells or OEC-M1 cells from a leukocyte background with high recovery rate (PC-3 cells: 76-83%, OEC-M1 cells: 61-68%), and high purity (PC-3 cells: 74-82%, OEC-M1 cells: 64-66%) (set flow rate: 0.1 μl min(-1) and sample volume: 1 μl). The latter is beyond what is currently possible in the conventional CTC isolations. Moreover, the viability of isolated cancer cells was evaluated to be as high as 94 ± 2%, and 95 ± 3% for the PC-3, and OEC-M1 cells, respectively. Furthermore, the isolated cancer cells were also shown to preserve their proliferative capability. As a whole, this study has presented an ODEP-based microfluidic platform that is capable of isolating CTCs in a continuous, label-free, cell-friendly, and particularly highly pure manner. All these traits are found particularly meaningful for exploiting the harvested CTCs for the subsequent cell-based, or biochemical assays.

Cell separation using tilted-angle standing surface acoustic waves

“…When separating cells with distinct physical properties, using methods that exploit differences in cells' physical parameters could be advantageous due to their label-free nature and ease of use (11,12). Many techniques are available to separate cells based on physical properties; they include filtration, centrifugation, acoustics, optics, and dielectrophoresis (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). Among these techniques, acoustic-based approaches are advantageous because of their biocompatibility and label-free nature (25,(27)(28)(29)(30)(31)(32).…”

Monitoring the dielectric response of single cells following mitochondrial adenosine triphosphate synthase inhibition by oligomycin using a dielectrophoretic cytometer

“…1,2 DEP has been employed in blood cells, 3-5 stem cell differentiation, 6,7 cancerous cells that are multidrug resistant (MDR), 8 circulating tumour cells, 9 viability, 10 and apoptosis tracking. 11,12 DEP of cells is influenced by many factors such as membrane capacitance, cytoplasm conductivity and cytoplasm permittivity.…”

Circulating tumor-cell detection and capture using microfluidic devices

“…This phenomenon allowed the applied voltage to drop across the liquid layer, producing a locally non-uniform electric field at the illuminated regions [63]. With this method, the recovery rate was 76-83% for PC-3 cells, and 61-68% for OEC-M1 cells with~95% viability [62]. The viability of the captured CTCs also depended on the applied voltage and the frequency of the DEP field, so DEP operation conditions needed to be carefully optimized to avoid collection of non-viable cells [64,65].…”

“…Lee and co-workers developed a high-purity CTC-isolation technique based on optically-induced DEP (ODEP) [62], which featured a sandwich structure with top and bottom layers made of indium-tin-oxide (ITO) glass, and the bottom layer had a photoconductive coating (hydrogenated amorphous silicon). Between these layers, there was a liquid layer containing the sample.…”