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A Tiered Microchip System for High Purity Isolation of Rare Cells from Blood
thesisposted on 15.12.2020, 21:56 by Onur Gur
Rare circulating cells are becoming a subject of interest due to their potential clinical applications to replace invasive procedures. Due their low presence in blood (as low as 1 in 1 ml of blood) various platforms are developed to capture and isolate them. Common limitations of current platforms include the inability to process large volumes of blood without an initial volume reduction step such as centrifugation, reliance on a single antibody for the capture, and the difficulty of releasing and retrieving the captured cells with high purity. A rare cell retrieval platform with high throughput operation and high purity retrieval is needed to capture these rare cells by processing large volumes of blood.
In this thesis study, we have developed a two-tiered microchip system to capture and retrieve rare cells from blood samples with high purity. The first module of the system is a high throughput microfluidic interface that is used to immunomagnetically isolate targeted rare cells from whole blood, and discard > 99.999% of the unwanted leukocytes. The second module is a microwell array that furthers the purification by magnetically guiding each cell into a separate well concurrently, and allows individual retrieval of each cell. Even though the system we have developed is applicable to many fields pertaining to rare cell capture, here we demonstrate the proof-of-concept using model cell lines that represent circulating fetal trophoblasts. We describe the design, operation as well as the experimental characterization of the system. Our characterization results show that the process can be completed within 145 minutes from the very beginning till the retrieval of a target cell, and can provide efficiencies and purities that are as high as 100%.
In order to demonstrate a real-world use case for our device, we present preliminary experiments done with blood samples from pregnant women. We show that we are able to retrieve candidate fetal cells under 167 minutes. Future work will be focused on sequencing the candidate fetal cells retrieved from maternal samples to confirm their fetal origin as well as enhancing system performance in maximizing the number of cells captured.