Two-stage microfluidic chip for selective isolation of circulating tumor cells (CTCs).

Over the past few decades, circulating tumor cells (CTCs) have been studied as a means of overcoming cancer. However, the rarity and heterogeneity of CTCs have been the most significant hurdles in CTC research. Many techniques for CTC isolation have been developed and can be classified into positive enrichment (i.e., specifically isolating target cells using cell size, surface protein expression, and so on) and negative enrichment (i.e., specifically eluting non-target cells). Positive enrichment methods lead to high purity, but could be biased by their selection criteria, while the negative enrichment methods have relatively low purity, but can isolate heterogeneous CTCs. To compensate for the known disadvantages of the positive and negative enrichments, in this study we introduced a two-stage microfluidic chip. The first stage involves a microfluidic magnetic activated cell sorting (μ-MACS) chip to elute white blood cells (WBCs). The second stage involves a geometrically activated surface interaction (GASI) chip for the selective isolation of CTCs. We observed up to 763-fold enrichment in cancer cells spiked into 5 mL of blood sample using the μ-MACS chip at 400 μL/min flow rate. Cancer cells were successfully separated with separation efficiencies ranging from 10.19% to 22.91% based on their EpCAM or HER2 surface protein expression using the GASI chip at a 100 μL/min flow rate. Our two-stage microfluidic chips not only isolated CTCs from blood cells, but also classified heterogeneous CTCs based on their characteristics. Therefore, our chips can contribute to research on CTC heterogeneity of CTCs, and, by extension, personalized cancer treatment.

Hyun KA ，Lee TY ，Lee SH ，Jung HI ... -  《-》

Selective isolation of magnetic nanoparticle-mediated heterogeneity subpopulation of circulating tumor cells using magnetic gradient based microfluidic system.

Relocation mechanisms of the circulating tumor cells (CTCs) from the primary site to the secondary site through the blood vessel network cause tumor metastasis. Despite of the importance to diagnose the cancer metastasis by CTCs, still it is formidable challenge to use in the clinical purpose because of the rarity and the heterogeneity of CTCs in the cancer patient's peripheral blood sample. In this study we have developed magnetic force gradient based microfluidic chip (Mag-Gradient Chip) for isolating the total number of CTCs in the sample and characterizing the state of CTCs simultaneously with respect to the epithelial cell adhesion molecule (EpCAM) expression level. We have synthesized magnetic nanoparticles (MNPs) using hydrothermal method and functionalized anti-EpCAM on their surface for the specific binding with CTCs. The Mag-Gradient Chip designed to isolate and classify the CTCs by isolating at the different location in the chip using magnetic force differences depending on the EpCAM expression level. We observed 95.7% of EpCAM positive and 79.3% of EpCAM negative CTCs isolated in the Mag-Gradient Chip. At the same time, the 71.3% of isolated EpCAM positive CTCs were isolated at the first half area whereas the 76.9% of EpCAM negative CTCs were collected at the latter half area. The Mag-Gradient Chip can isolate the 3ml of heterogeneous CTCs sample in 1h with high isolating yield. The EpCAM expression level dose not means essential condition of the metastatic CTCs, but the Mag-Gradient Chip can shorten the date to diagnose the cancer metastasis in clinic.

Kwak B ，Lee J ，Lee D ，Lee K ，Kwon O ，Kang S ，Kim Y ... -  《-》

Negative enrichment of circulating tumor cells using a geometrically activated surface interaction chip.

Hyun KA ，Lee TY ，Jung HI 《-》

Spiral shape microfluidic channel for selective isolating of heterogenic circulating tumor cells.

Detecting heterogenic tumor cells that are traveling in our body through blood stream for the tumor metastasis is one way for cancer prognosis. Due to the heterogeneity of circulating tumor cells (CTCs), further identification of tumor cell types should be accompanied with CTCs isolation from blood cells in peripheral blood sample. Both negative enrichment and recollection of isolated CTCs are required in the downstream analysis, which are time-consuming, labor-intensive, and massive equipment required. To solve these limitations, we have developed a simple and disposable spiral shape microfluidic channel that can separate all CTCs from blood cells, and at the same time, can identify the types of CTCs based on epithelial cell adhesion molecule (EpCAM) expression level. Two different types of tumor cells, MCF-7 and MDA-MB-231, both from the same origin of breast carcinoma cells, were used to demonstrate the functionality of the developed system. The spiral channel system could capture the EpCAM positive and negative CTCs with 96.3% and 81.2% purity, respectively, while both EpCAM positive and negative CTCs were differently positioned along the microfluidic channel. The average selectivity of EpCAM positive and negative CTCs is 6.1:4.8. In addition, the throughput of the system was optimized at a sample flow rate of 150µl/min. The developed system successfully demonstrated its potential to identify biomarkers, including EpCAM, for detecting the heterogenic CTCs.

Kwak B ，Lee J ，Lee J ，Kim HS ，Kang S ，Lee Y ... -  《-》

Nanoroughened adhesion-based capture of circulating tumor cells with heterogeneous expression and metastatic characteristics.

Chen W ，Allen SG ，Reka AK ，Qian W ，Han S ，Zhao J ，Bao L ，Keshamouni VG ，Merajver SD ，Fu J ... -  《BMC CANCER》