Abstract 4140: Negative enrichment of circulating tumor cells using geometrically activated surface interaction (GASI) chip.

Abstract

Abstract Circulating tumor cells (CTCs), existing extremely rare in peripheral blood (the order of one cell per 1* 106 nucleated cells), have attracted a lot of attention as they can be exploited to investigate metastasis. The isolation of intact CTCs is challenging owing to their rarity and heterogeneous features. A lot of methodologies for CTCs enrichment in blood were focused using antibodies to epithelial cell adhesion molecule (EpCAM). However, the recent studies found that the CTCs undergo a process of epithelial-mesenchymal transition (EMT) to adapt oneself to new circumstances which is blood stream and down regulated EpCAM expression on their surface. It is thought that the many CTCs may escape detection by conventional detection methods. So, we decided to use the negative enrichment (i.e. capturing WBCs which are non-target cells and eluting CTCs which are target cells) for isolation of intact and heterogeneous CTCs. To capture a large number of WBCs in the channel, we developed a geometrically activated surface interaction (GASI)-Chip which is based on the asymmetric herringbone that generate the enhanced mixing flows increasing the surface interaction between the WBCs and CD45 antibody-conjugated channel surface. Using the optimized experimental conditions, we isolated 94.67% of MCF-7 cells (breast cancer cell line) and eliminated 98.94% of Jurkat cells (human T cell lymphoblast like cell line) at 20 μL/min flow rate. Based on these results, we have attempted to isolate CTCs from patients with several kinds of metastatic cancer patients under the same conditions. The blood samples (1ml) were collected from breast, gastric and lung cancer patients, respectively. After blood samples passed through the GASI-Chip, collected cells were fixed on a slide glass and stained with DAPI for DNA content, PE conjugated Cytokeratin for CTC, and FITC conjugated CD45 for WBC. Following imaging the slide glass, captured images were examined carefully with predefined criteria (DAPI positive, Cytokeratin positive, CD45 negative). The number of isolated CTCs varied from 1 to 51 in 1 ml of blood. Although this device was not intended to process full clinical blood draws, which typically yield 7.5 mL, quite a number of CTCs can be detected from only 1ml of blood compared with other approaches based on the characters of CTCs such as size. Furthermore, the intact and heterogeneous CTCs can be isolated regardless of EpCAM expression because our devices do not require any labeling processes (e.g., EpCAM antibody for CTC). Citation Format: Hyo-Il Jung, Kyung-A Hyun, Tae Yoon Lee. Negative enrichment of circulating tumor cells using geometrically activated surface interaction (GASI) chip. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4140. doi:10.1158/1538-7445.AM2013-4140