Advancing Microfluidic Tumour-on-a-chip Technologies by Integrating Multicellular Tumour Spheroids and Angiogenic Vessels

Angiogenesis, the development of new blood vessels from existing vasculature, is a key mechanism in cancer progression. Solid tumours that are depleted of nutrients induce angiogenesis to recruit blood vessels for access to nutrients and a pathway for metastasis. Anti-angiogenic therapies have been developed, but toxicities, resistance, and limited efficacy have been reported and there remains a strong need for development of in vitro platforms that can model tumour-induced angiogenesis to conduct fundamental and clinical research. Traditional in vitro assays include 2D cell cultures that do not recapitulate cellular functions that are unique to a 3D geometry and are therefore unsuitable for investigations of complex phenomena such as tumour angiogenesis. Microfluidic technology has emerged as a popular tool for 3D cell cultures such as tumour-on-a-chip models that recapitulate the physiological complexities of a tumour microenvironment. The development of a microfluidic model for tumour-induced angiogenesis would facilitate fundamental research on the underlying cellular mechanisms, and clinical research to develop new drug candidates. To accomplish this, a deeper understanding of the microfluidic cell culture components is needed, along with a device design that is well suited for analysis of tumour-induced angiogenesis. The objective of this thesis was to examine the elements of a microfluidic model of tumour-endothelial interactions and develop a microfluidic cell culture where tumour-induced angiogenesis can be observed and quantified. We first characterized 3D spheroids, revealing correlations between external, internal, and secretory profile characteristics of 3D tumour spheroids as they relate to angiogenic potential. Next, we sought to understand how best to incorporate fibroblasts for their critical role in achieving 3D sprout morphology. We identified the utility of fibroblast configuration for influencing the extent of endothelial response in microfluidic co-culture. Finally, we introduced a new microfluidic device for spheroid-endothelial co-cultures where spheroid-induced sprouting was demonstrated using multiple spheroid types and quantified using image analysis. Overall, these studies have developed insights on the characteristics of 3D tumour spheroids, fibroblasts, and endothelial sprouts that allow these cell culture features to be wielded as biological tools, and demonstrated the utility of microfluidics for complex cell cultures to study tumour angiogenesis and cancer progression.Ph.D