Circulating tumor cells (CTCs) and circulating clusters of cancer and stromal cells have been identified in the blood of patients with malignant cancer and can be used as a diagnostic for disease severity, assess the efficacy of different treatment strategies and possibly determine the eventual location of metastatic invasions for possible treatment. There is thus a critical need to isolate, propagate and characterize viable CTCs and clusters of cancer cells with their associated stroma cells. Here, we present a microfluidic device for mL/min flow rate, continuous-flow capture of viable CTCs from blood using deterministic lateral displacement (DLD) arrays. We show here that a DLD array device can isolate CTCs from blood with capture efficiency greater than 85% CTCs at volumetric flow rates of up to 10 mL/min with no effect on cell viability

We previously developed a Deterministic Lateral Displacement (DLD) microfluidic method in silicon to separate cells of various sizes from blood (Davis et al., Proc Natl Acad Sci 2006;103:14779-14784; Huang et al., Science 2004;304:987-990). Here, we present the reduction-to-practice of this technology with a commercially produced, high precision plastic microfluidic chip-based device designed for automated preparation of human leukocytes (white blood cells; WBCs) for flow cytometry, without centrifugation or manual handling of samples. After a human blood sample was incubated with fluorochrome-conjugated monoclonal antibodies (mAbs), the mixture was input to a DLD microfluidic chip (microchip) where it was driven through a micropost array designed to deflect WBCs via DLD on the basis of cell size from the Input flow stream into a buffer stream, thus separating WBCs and any larger cells from smaller cells and particles and washing them simultaneously. We developed a microfluidic cell processing protocol that recovered 88% (average) of input WBCs and removed 99.985% (average) of Input erythrocytes (red blood cells) and >99% of unbound mAb in 18 min (average). Flow cytometric evaluation of the microchip Product, with no further processing, lysis or centrifugation, revealed excellent forward and side light scattering and fluorescence characteristics of immunolabeled WBCs. These results indicate that cost-effective plastic DLD microchips can speed and automate leukocyte processing for high quality flow cytometry analysis, and suggest their utility for multiple other research and clinical applications involving enrichment or depletion of common or rare cell types from blood or tissue samples.

Microfluidic deterministic lateral displacement (DLD) arrays have been applied for fractionation and analysis of cells in quantities of ~100 μL of blood, with processing of larger quantities limited by clogging in the chip. In this paper, we (i) demonstrate that this clogging phenomenon is due to conventional platelet-driven clot formation, (ii) identify and inhibit the two dominant biological mechanisms driving this process, and (iii) characterize how further reductions in clot formation can be achieved through higher flow rates and blood dilution. Following from these three advances, we demonstrate processing of 14 mL equivalent volume of undiluted whole blood through a single DLD array in 38 minutes to harvest PC3 cancer cells with ~86% yield. It is possible to fit more than 10 such DLD arrays on a single chip, which would then provide the capability to process well over 100 mL of undiluted whole blood on a single chip in less than one hour.

We describe a microfluidic device for on-chip chemical processing, such as staining, and subsequent washing of cells. The paper introduces "separator walls" to increase the on-chip incubation time and to improve the quality of washing. Cells of interest are concentrated into a treatment stream of chemical reagents at the first separator wall for extended on-chip incubation without causing excess contamination at the output due to diffusion of the unreacted treatment chemicals, and then are directed to the washing stream before final collections. The second separator wall further reduces the output contamination from diffusion to the washing stream. With this approach, we demonstrate on-chip leukocyte staining with Rhodamine 6G and washing. The results suggest that other conventional biological and analytical processes could be replaced by the proposed device.