Rapid Staining of Circulating Tumor Cells in Three-Dimensional Microwell Dialysis (3D-μDialysis) Chip

Leukocyte Depletion and Size-Based Enrichment of Circulating Tumor Cells Using a Pressure-Sensing Microfiltration Device

Considering the challenges in isolating circulating tumor cells (CTCs) pertaining to cellular stress and purity, we report the application of a blood microfiltration device as an optimal approach for noninvasive liquid biopsy to target CTCs. We experimentally analyzed the filtration behavior of the microfilter using pressure sensing to separate tumor cells from leukocytes in whole blood. This approach achieved an average recovery of >96% of the spiked tumor cells and depletion of >99% of total leukocytes. Furthermore, we carried out genomic profiling of the CTCs using the blood microfiltration device. The method was also applied in a clinical setting; DNA amplification was performed using a small number of microfiltered CTCs and epidermal growth factor receptor mutations were successfully detected to characterize the efficacy of molecularly targeted drugs against lung cancer. Overall, the proposed method can provide a tool for evaluating efficient filtration pressure to concentrate CTCs from whole blood.

Enumerating Circulating Tumor Cells with a Self-Assembled Cell Array (SACA) Chip: A Feasibility Study in Patients with Colorectal Cancer

Colorectal cancer (CRC) is the second most common cause of cancer-related death worldwide. Detecting and enumerating circulating tumor cells (CTCs) in patients with colorectal cancer emerged as an important prognostic tool which provides a direct estimate of metastatic potential. Improving the turnaround time and decreasing sample volume is critical for incorporating this liquid biopsy tool into routine practice. The objective of the current study was to validate the clinical feasibility of a self-assembled cell array (SACA) chip, a CTC counting platform with less than 4 h turnaround time, in patients with newly diagnosed colorectal cancers. In total, 179 patients with newly diagnosed colorectal cancers from a single institute were enrolled. Epithelial cell adhesion molecule positive (EpCAM(+)), cluster of differentiation 45 negative (CD45(-)) cells were isolated and enumerated from 2 mL of peripheral vein blood (PB) and inferior mesenteric vein blood (IMV) samples obtained during surgery. We found that the CTC count in PB but not IMV correlates with disease stages. Neoadjuvant chemotherapy did not lead to decreased CTC count in both types of blood samples. With cutoffs of four CTCs per 2 mL of blood, and serum carcinoembryonic antigen (CEA) level of 5 ng/mL, patients with non-metastatic disease were more likely to experience recurrence if they had high PB CTC count and high serum CEA concentration (odds ratio, 8.9). Our study demonstrates the feasibility of enumerating CTCs with a SACA chip in patients with colorectal cancer.

A simple microdevice for single cell capture, array, release, and fast staining using oscillatory method

Microchips that perform single cell capture, array, and identification have become powerful tools for single cell studies, which can reveal precise underlying mechanisms among bulk cell populations. However, current single cell capture and on-chip immunostaining methods consume more time and reagent than desired. To optimize this technology, we designed a novel trap structure for single cell capture, array, and release, and meanwhile an oscillatory method was used to perform rapid on-chip cell immunostaining. The trap structure array used equal distribution of lateral flow to achieve single cell array in high velocity flows and decrease the risk of clogging. A length of glass capillary with a sealed bubble was inserted into the outlet so that it could act in a manner analogous to that of a capacitor in an RC circuit. By applying one periodic air pressure to the inlet, oscillation motion was generated, which significantly enhanced the on-chip reaction efficiency. In addition, the oscillation performance could be easily regulated by changing the length of the capillary. The trapped cells could maintain their positions during oscillation; hence, they were able to be tracked in real time. Through our trap microchip, 12 μm microbeads were successfully trapped to form a microarray with a capture efficiency of ∼92.7% and 2 μm microbeads were filtered. With an optimized oscillation condition (P_push = 0.03 MPa, f = 1 Hz, L = 3 cm), fast on-chip immunostaining was achieved with the advantages of less time (5 min) and reagent (2 μl) consumption. The effectiveness of this method was demonstrated through quantitative microbead and qualitative Caco-2 cell experiments. The device is simple, flexible, and efficient, which we believe provides a promising approach to single cell heterogeneity studies, drug screening, and clinical diagnosis.