Microfluidics for Cell Culture and Single Cell Assays

Elucidating molecular processes that govern cell function is paramount in forming a basis for understanding human health and treating disease. Research is presently limited by investigating in bulk, where information on critical subsets of cells is lost through averaging across an entire population. Therefore, biological and biomedical fields have become increasingly interested in methods that enable the handling of cells individually and facilitate studies into cellular heterogeneity. Existing techniques, however, are often associated with high costs and limited throughput. To address these shortcomings, my PhD has focussed on the methodological advancement of cell culture and assay techniques by taking advantage of the reduced size and volume scales of microfluidics. This dissertation describes the development of two micro-scale cell culturing platforms. The first approach involves the generation of hydrogel-based microgels for cell encapsulation. The system aims to provide a versatile and high throughput platform that imposes minimal cellular stress and uses readily available materials to reduce costs compared to existing methods. The potential of cell-laden microgels as an assay system is demonstrated by performing a digital toxicity assay, which demonstrates the ability to record individual cell responses. Furthermore, the formation of composite and core-shell microgels is explored to provide control over the internal structure and composition of the microgels. Using this approach, the platform is shown to be easily adaptable to incorporate various materials, such as extracellular matrix-like components, to provide a biomimetic microenvironment that more closely matches physiological tissue conditions in comparison to conventional two-dimensional methods. This system facilitates three- dimensional cell culture and spheroid formation of various cell types, including adherent cells that require a scaffolding structure. The second approach focusses on neuronal cell culture directly on-chip, where cells are compartmentalised by the microstructures of the microfluidic device. Modulation of the device explores the isolation of axon growth between donor and acceptor cells to facilitate the study of infectious tau protein propagation involved in neurodegenerative diseases. Collectively, this dissertation represents my work in combining microfluidic techniques with cell studies to develop platforms that will readily enable research into cellular heterogeneity and individual cellular processes.ERC, funding for 3 years of PhD study; CRUK, partial funding for collaborative projec