Development of Microfluidic Platforms in Extracellular Vesicle Enrichment and Cancer Biomedical Applications

Abstract

Currently, microfluidic techniques enable a wide range of applications in the biomedical field. Scientists can control small amounts of fluids on a microscale through applications from drug screening panels that may further develop into patient-tailored point-of-care (POC) devices to studies on cancer cells under physical and chemical stimulation. This research is particularly important, considering that the majority of cancer-related deaths can be attributed to metastasis, a complex and multistep procedure that remains far from being understood. In vivo experiments involving the complex tumour microenvironment (TME) have previously experienced reproducibility issues due to tumour heterogeneity. This thesis aimed to develop microfluidic devices to address key questions in cancer research, namely, key communicators’ role within the TME, drug response evaluation and isolation of enriched extracellular vesicles (EV) by using advanced 3D-printed microfluidic platforms.

Given that exosomes contribute significantly to understanding the TME, we aimed to investigate the effects of EVs and mechanical stress on cancer cell migration. A physical confinement device using a printed copper board master was fabricated, with migration channel heights ranging from 6 microns to 30 microns as control. The isolated EVs were used to explore synergy between confined and CD81-abundant EVs, revealing effects on cancer single-cell migration.

This work leads to great interest in EV quality and purity and advancements on 3D-printed microfluidic platforms via tandem flow filtration principles for EV isolation and analysis. The utilization of 3D printing fabrication in microfluidic applications allowed for the creation of a Tandem Flow Filtration (TFF) device with modular pieces that can be assembled and finetuned by UV crosslinking post-processing. This innovative approach represents a significant advantage in developing complex biomedical devices. The isolated EVs are enriched in concentration and kept in viable conditions that are ready for downstream analysis.

Furthermore, focusing on another patient-oriented approach, a 3D-printed drug screening device based on the principle of hydrodynamic traps was selected based on different design principles. The device fills standardized volumes of microdissected tissues until fully occupied. Various mechanisms were explored and developed before further application. A device design was selected for drug screening based on the principle of hydraulic traps. A method was also developed to produce standard volumes of microdissected tissues. Compared with the conventional dish-grown assay, this developed method significantly enhances readability, scalability and operation.

Overall, three microfluidic platforms in EV enrichment, TME application and cell migration were developed. These platforms offer a comprehensive approach to access personalised cancer progression and treatment diagnosis transitioning devices into the POC sector. The advancements in 3D printing fabrication and monitor resolution technology contribute to the development of robust personalised cancer diagnosis devices. These advancements enable precise and reliable diagnostic tools, further enhancing the field of personalised medicine for patients with cancer.

Date of Award	14 Apr 2025
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	M YANG (Supervisor) & Liang ZHANG (Co-supervisor)