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

Influence of Geometry and Surrounding Conditions on Fluid Flow in Paper-Based Devices

Fluid flow behaviour in paper is of increasing interest due to the advantages and expanding use of microfluidic paper-based analytical devices (known as µPADs). Applications are expanding from those which often have low sample fluid volumes, such as diagnostic testing, to those with an abundance of sample fluid, such as water quality testing. The rapid development of enhanced features in μPADs, along with a need for increased sensitivity and specificity in the embedded chemistry requires understanding the passively-driven fluid motion in paper to enable precise control and consistency of the devices. It is particularly important to understand the influence of parameters associated with larger fluid volumes and to quantify their impact. Here, we experimentally investigate the impacts of several properties during imbibition in paper, including geometry (larger width and length) and the surrounding conditions (humidity and temperature) using abundant fluid reservoirs. Fluid flow velocity in paper was found to vary with temperature and width, but not with length of the paper strip and humidity for the conditions we tested. We observed substantial post-wetting flow for paper strips in contact with a large fluid reservoir

Teaching credible validation and verification methods to a large, multidisciplinary first-year engineering design class

This paper describes our experiences in teaching credible validation and verification methods to a class of 250 first-year Engineering Science students at the University of Toronto. While our students have previously developed proof-of-concept prototypes, this was the first year that testing their prototypes against key design requirements – and substantially integrating stakeholder feedback into their projects – were course expectations. Core strategies to support our students included leveraging the expertise of a multidisciplinary teaching team; training students to collect and interpret data from community stakeholders; demystifying prototyping and testing through small-scale activities; and legitimizing our expectations through real-world examples. Student design teams generally performed well with respect to validation and verification criteria on their summative project evaluations. Most teams effectively integrated stakeholder feedback with other research into developing and refining their designs, and demonstrated that their prototypes addressed key metrics. Challenges to be addressed in future course iterations are discussed.The authors acknowledge funding from the Canadian Institutes of Health Research Operating Grants (CIHR MOP 142178) (VK), the AGE-WELL Network of Centres of Excellence in Technology & Aging Graduate Student Scholarships (VK),Toronto Rehabilitation Institute Graduate Student Scholarships (VK), the Ontario Ministry for Research & Innovation (NW), the Natural Sciences & Engineering Research Council of Canada (NW, AF), the Training in Organ-on-a-Chip Engineering Program Scholarships (NW), and the Weber & Mariano Graduate Scholarships (NW). We also gratefully acknowledge funding from U of T’s Institute of Biomaterials & Biomedical Engineering (VK) and Division of Engineering Science (NW) to present at CEEA 2017

Who you are and how you work: Embedding personality in engineering design

As the Engineering profession increasingly explores the complex relationships between technology and society, the responsibility of engineers is evolving to include considering the socio-technical complexities in which their technology will be embedded [1]. This evolution has led to interest in teaching empathy and reflexivity in undergraduate engineering education, in part to prepare student engineers for effective community engagement in their engineering practice [2] [3]. This practice paper discusses considerations, approaches, and theories that informed our design practice as we incorporated positionality into our course. Positionality was introduced as a foundational design tool to approximately 300 students in a first-year design course at a large, public, research-intensive university. In this work we discuss the integration of positionality as a framework to facilitate self-awareness, intentionality, leadership, reflexivity, and empathy in individual and team engineering design activities

Paper-Based Microfluidic Device with a Gold Nanosensor to Detect Arsenic Contamination of Groundwater in Bangladesh

In this paper, we present a microfluidic paper-based analytical device (μPAD) with a gold nanosensor functionalized with α-lipoic acid and thioguanine (Au–TA–TG) to detect whether the arsenic level of groundwater from hand tubewells in Bangladesh is above or below the World Health Organization (WHO) guideline level of 10 μg/L. We analyzed the naturally occurring metals present in Bangladesh groundwater and assessed the interference with the gold nanosensor. A method was developed to prevent interference from alkaline metals found in Bangladesh groundwater (Ca, Mg, K and Na) by increasing the pH level on the μPADs to 12.1. Most of the heavy metals present in the groundwater (Ni, Mn, Cd, Pb, and Fe II) did not interfere with the μPAD arsenic tests; however, Fe III was found to interfere, which was also prevented by increasing the pH level on the μPADs to 12.1. The μPAD arsenic tests were tested with 24 groundwater samples collected from hand tubewells in three different districts in Bangladesh: Shirajganj, Manikganj, and Munshiganj, and the predictions for whether the arsenic levels were above or below the WHO guideline level agreed with the results obtained from laboratory testing. The μPAD arsenic test is the first paper-based test validated using Bangladesh groundwater samples and capable of detecting whether the arsenic level in groundwater is above or below the WHO guideline level of 10 μg/L, which is a step towards enabling the villagers who collect and consume the groundwater to test their own sources and make decisions about where to obtain the safest water