Real-Time Detection of Tumor Cells during Capture on a Filter Element Significantly Enhancing Detection Rate.

Astrid Lux,Tanja Maucher,Hannah Bott,Jochen Hoffmann,Nisar Peter Malek,Roland Zengerle

doi:10.3390/bios11090312

Abstract

Circulating tumor cells (CTCs) that enter the bloodstream play an important role in the formation of metastases. The prognostic significance of CTCs as biomarkers obtained from liquid biopsies is intensively investigated and requires accurate methods for quantification. The purpose of this study was the capture of CTCs on an optically accessible surface for real-time quantification. A filtration device was fabricated from a transparent material so that capturing of cells could be observed microscopically. Blood samples were spiked with stained tumor cells and the sample was filtrated using a porous structure with pore sizes of 7.4 µm. The possible removal of lysed erythrocytes and the retention of CTCs were assessed. The filtration process was observed in real-time using fluorescence microscopy, whereby arriving cells were counted in order to determine the number of CTCs present in the blood. Through optimization of the microfluidic channel design, the cell retention rate could be increased by 13% (from 76% ± 7% to 89% ± 5%). Providing the possibility for real-time detection significantly improved quantification efficiency even for the smallest cells evaluated. While end-point evaluation resulted in a detection rate of 63% ± 3% of the spiked cells, real-time evaluation led to an increase of 21% to 84% ± 4%. The established protocol provides an advantageous and efficient method for integration of fully automated sample preparation and CTC quantification into a lab-on-a-chip system.

Highlights

Introduction published maps and institutional affilCirculating tumor cells, which are shed from the primary tumor into the vasculature, are described as the major cause for metastases [1]
We present a method for the Circulating tumor cells (CTCs) capture on a porous structure and the advantages of real-time detection during the filtration process for coping with the challenge of missing small and deformable cells in a filtration approach with end-point optical detection of the captured cells after the filtration process
In this study, we focused on examining the of the detection rate based on real-time detection in comparison to end-point detection optimization of the detection rate based on real-time detection in comparison to end-point using cells with known homogenous epithelial cell adhesion molecule (EpCAM)-expression as model antigen

Summary

Introduction

Circulating tumor cells, which are shed from the primary tumor into the vasculature, are described as the major cause for metastases [1]. These cells have been found in the blood of breast, lung, prostate, and colon cancer patients and have been correlated to poorer outcome and tumor aggressiveness [2,3,4,5]. A decrease in the number of CTCs seems to correlate to treatment response, whereas an increase might require adaptation of the therapy [6]. Besides the enumeration, phenotyping, cultivation of spheroids and organoids, and genotyping thereof is possible after isolation of CTCs and could provide valuable information for therapy adaptation [7]. Due to the rarity and heterogeneity of the CTCs, their enumeration is a huge technological challenge

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