Microfluidic interfacing technique for high-throughput analysis of breast cancer tissue section

Abstract

In this thesis, the development of microfluidic interfacing technique for the efficient analysis of breast cancer tissue section is presented. First, we demonstrated a microfluidic platform that allows entire immunohistochemistry (IHC) to be performed on a microfluidic environment. To overcome the limited application of the microfluidic platform to IHC processes, we developed the microfluidic chip made of poly(urethane acrylate) (PUA) which has high resistance to organic solvents. A novel wall-structure of the chip enables the reversible assembly to section slide despite the high Young’s modulus of PUA. Including the deparaffinization process using organic solvents, the entire IHC processes were implemented on a microfluidic environment. The IHC results by both on-chip and conventional method were evaluated to compare the immunostaining quality and showed an equivalent level while reducing the total process time to 40% (150 min to 60 min). In addition, the verification result using HER2-overexpressive breast cancer tissue showed the potential of microfluidic interfacing technique for medical application.

We also demonstrated the microfluidic interfacing technique for the analysis of tissue microarray (TMA). A microfluidic chip which has bundles of multiplexed microchannel was designed to align on each core of TMA. The chip was reversibly assembled with TMA by pressure to provide a microfluidic multiplexed immunostaining environment to each core of TMA. Based on these, we proposed a ‘barcode-IHC’ concept to analyze the expression characteristics of four biomarkers by multiplex immunostaining. The combination of four bar-like immunostaining results with different intensities reveal the unique pattern depending on the samples so it can be utilized as a standard for diagnosis. The verification of the barcode-IHC concept using a cell microarray (CMA) consisting of six different breast cell lines showed that distinct barcode results were obtained corresponding to the characteristics of each cell line. The barcode-IHC result performed on 90 breast cancer tissue cores using TMA and confirmed an agreement rate over 90% by comparing the results obtained by conventional method. Also, the barcode-IHC result of multiplexed immunostaining with different antibody sequences showed over 87% agreement.