摘要：血液中某些稀少細胞的檢測，往往能提供作為臨床疾病診斷之重要指標。例如，轉移性癌症是腫瘤釋放循環腫瘤細胞 (circulating tumor cells, CTC) 到病人的血液或淋巴管中，經由血液或淋巴循環系統散布到身體其他器官，並在健康器官中形成新的腫瘤，所以在臨床診斷中，能提供醫生病人血液中的CTC可作為治療效果的評估和治療過程的監視。然而CTC在血液中的數量極為稀少，每十億血球細胞中只有數個CTC，因此分離和偵測血液中的CTC為工程和醫學上的重要的挑戰。
Abstract: Blood are primary sample loaded with clinical information. With the ease of sample collection enjoying wide acceptance from patients, peripheral blood should continue to play a significant role in development of biomedical devices in the near future. Constituency in 1mL of blood include roughly 5x109 red blood cells (RBC), 5x106 white blood cells (WBC) and trace amount of other nucleated cells. These nucleated components can contain cells of significant clinical value, e.g. circulating tumor cells (CTC). These CTC are known to be metastatic tumor cells from their primary site – e.g. breast, colon/rectal, lung etc. – enroute to distant secondary site. Ninety percent of cancer mortality arises from metastasis, justifying much research in interrogating their prognosis value and other disease management schemes via CTC in the literature. The major hurdle lies with constituency of CTC can be as low as 1 in 109 blood cells, equivalent to finding a few persons in the whole world.
Several assays for detecting CTCs have been introduced in recent years. Most CTC detection assays, such as the CellSearch technique (CTCs measured with the FDA-approved), relies on EpCAM expression on tumor cells. However, expression levels of EpCAM are known to be down-regulated for the most invasive cells during the epithelial-mesenchymal transition (EMT) process. Moreover, it was recently reported that some tumor cells express low or no EpCAM, resulting in a limited binding efficiency. Sieuwerts1 has reported that using EpCAM for cell isolation does not recognize, in particular, normal-like breast cancer cells, which in general have aggressive features. Therefore, to provide a method capable to enrich and detect most types of CTCs, could improve the sensitivity and reproducibility for CTC enrichment and detection.
This proposal aims to study the effect of blood cell separation via two methods: electrokinetic-based approach via dielectrophoresis and density-based separation combined with immuno-magnetic cell separation approach on a microfluidic disk. Dielectrophoresis approach has its advantage due to strong size dependency (L3). Hence, tumor cells (15~30um) with majority known to be larger than regular blood cells (red blood cell~7um; white blood cell~10um) might be separated efficiently. Density-based approach is used to remove red blood cell and immuno-magnetic cell separation approach is used to remove white blood cells.
circulating tumor cells