Efficient capture of circulating tumor cells with a novel immunocytochemical microfluidic device

Abstract

Ability to perform cytogenetic interrogations on circulating tumor cells (CTCs) from the blood of cancer patients is vital for progressing toward targeted, individualized treatments. CTCs are rare compared to normal (bystander) blood cells, found in ratios as low as 1:10 9 . The most successful isolation techniques have been immunocytochemical technologies that label CTCs for separation based on unique surface antigens that distinguish them from normal bystander cells. The method discussed here utilizes biotin-tagged antibodies that bind selectively to CTCs. The antibodies are introduced into a suspension of blood cells intending that only CTCs will display surface biotin molecules. Next, the cell suspension is passed through a microfluidic channel that contains about 9000 transverse, streptavidin coated posts. A CTC making contact with a post has the opportunity to engage in a biotin-streptavidin reaction that immobilizes the cell. Bystander blood cells remain in suspension and pass through the channel. The goal of the present study is to establish the technical performance of these channels as a function of antigen density and operating conditions, especially flow rate. At 18 lL/min, over 70% of cells are captured at antigen densities greater than 30 000 sites/cell while 50% of cells are captured at antigen densities greater than 10 000. It is found that lower flow rates lead to decreasing cell capture probabilities, indicating that some streamlines develop which are never close enough to a post to allow cell-post contact. Future modeling and streamline studies using computational fluid dynamics software could aid in optimization of channel performance for capture of rare cells.

Development of the automated circulating tumor cell recovery system with microcavity array

“…Anti-EpCAM antibody-coated magnetic particles are used in immunomagnetic separation-based systems such as CellSearch system (Velidex, Raritan, NJ) that has been approved by FDA for the diagnosis of breast, prostate and colon cancers Xie et al, 2014;Xu et al, 2011). Many reports have been published on antibody-coated tools including microfluidic channel, needle, and magnetic nanoparticles with the aid of the antibodies, which recognize CTC specific markers (Durgadas et al, 2011;Kamande et al, 2013;Kirby et al, 2012;Nora Dickson et al, 2011;Park et al, 2014;Svensson et al, 2014;Wang et al, 2004). However, this assay format has a limitation to apply the basic protocol to various types of tumor cells because the expression level of surface makers, especially EpCAM (Punnoose et al, 2010), was varied with tumor types.…”

Efficient elusion of viable adhesive cells from a microfluidic system by air foam

“…[1][2][3][4][5][6][7] Despite allowing for the rapid isolation of these clinically relevant cell types, microfluidic methods are facing the challenge of releasing and recovering the isolated target cells for further biological analysis. 8 Due to the nature of low concentration of CTCs in whole cellular population after separation process, the acceptable efficiency of releasing cells should approach 100% for broader applications such as sensitively monitoring therapy response, diagnosis of early stage cancer, and analysis of genetic makeup.…”

Technologien zur Isolation im Blut zirkulierender Tumorzellen

“…Für diese Technologie ist eine gute Durchwirbelung der Strömung erforderlich, die wiederum die Häufigkeit des Zusammenstoßes von Tumorzellen mit den Säulen erhöht. Eine unregelmäßige Anordnung von Säulen unterschiedlicher Größe erhöht die Durchwirbelung [6]. Der sogenannte Fischgräten-Chip kommt ohne Säulen aus: Mikrorillen an den Wänden der Fluidkammer in einem fischgrätenförmigen Muster sorgen für eine Durchwirbelung des Blutes [7].…”

“…Um eine höhere Ausbeute von zirkulierenden Tumorzellen zu erhalten, verwenden einige Gruppen Cocktails von Antikörpern [6]. Dadurch können auch Tumorzellen, die nicht EpCAM-positiv sind, aus dem Blut gefischt werden.…”