Quantitative design strategies for fine control of oxygen in microfluidic systems

Shirure, Venktesh S.; Lam, Sandra; Shergill, Bhupinder; Chu, Yunli E.; Ng, Natalie R.; George, Steven C.

doi:10.1039/d0lc00350f

Cited by 21 publications

(18 citation statements)

References 28 publications

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“…Finite element modelling using COMSOL Multiphysics was used to inform design and confirmed generation of 12 unique concentrations (Fig 2A) and equal splitting of flow rates to the wells of each column using the equal-resistance distribution networks (Fig 2B). While oxygen gradients produced in mi-crofluidic devices can be robustly predicted and controlled through thorough modelling of variables such as fluid flow, reaction rates, and material properties 26,27 , isolating cells within a single well containing a single, quantized oxygen concentration has unique benefits for higher-throughput applications. Besides adapting into standard workflows, our method may be used to investigate O 2 as a standalone variable, decoupled from factors such as fluid flow or interaction with nearby cells growing at different concentrations along the gradient.…”

Section: Discussionmentioning

confidence: 99%

96-Well Oxygen Control Using a 3D-Printed Device

Szmelter

Jacob

Eddington

2020

Preprint

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Oxygen concentration varies tremendously within the body and has proven to be a critical variable in cell differentiation, proliferation, and drug metabolism among many other physiological processes. Currently, researchers study the gas’s role in biology using low-throughput gas-control incubators or hypoxia chambers in which all cells in a vessel are exposed to a single oxygen concentration. Here, we introduce a device which can simultaneously deliver 12 unique oxygen concentrations to cells in a 96-well plate and seamlessly integrate into biomedical research workflows. The device inserts into 96-well plates and delivers gas to the headspace thus avoiding undesirable contact with media. This simple approach isolates each well using gas-tight pressure resistant gaskets effectively creating 96 “mini-incubators”. Each of the twelve columns of the plate is supplied by a distinct oxygen concentration from a gas-mixing gradient generator supplied by two feed gases. The wells within each column are then supplied by an equal flow-splitting distribution network. Using equal feed flow rates, concentrations ranging from 0.6% to 20.5% were generated within a single plate. A549 lung carcinoma cells were then used to show that O2 levels below 9% caused a stepwise increase in cell death for cells treated with the hypoxia-activated anti-cancer drug Tirapirizamine (TPZ). Additionally, the 96-well plate was further leveraged to simultaneously test multiple TPZ concentrations over an oxygen gradient and generate a 3D dose response landscape. The results presented here show how microfluidic technologies can be integrated into, rather than replace, ubiquitous biomedical labware allowing for increased throughput oxygen studies.

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Section: Discussionmentioning

confidence: 99%

96-Well Oxygen Control Using a 3D-Printed Device

Szmelter

Jacob

Eddington

2020

Preprint

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“…The islets consumed oxygen and glucose, and secreted insulin with previously reported kinetic functions (27). The PDMS was permeable to oxygen and media entering the device was in equilibrium with the atmospheric oxygen (28). Glucose was introduced through the inlet and the insulin and glucose output was measured by using time integral of outlet amount over 10-minute intervals.…”

Section: Methodsmentioning

confidence: 99%

A vascularized 3D model of the human pancreatic islet for ex vivo study of immune cell-islet interaction

Bender

O’Donnell

Shergill

et al. 2021

Preprint

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Insulin is an essential regulator of blood glucose homeostasis that is produced exclusively by β cells within the pancreatic islets of healthy individuals. In those affected by diabetes, immune inflammation, damage, and destruction of islet β cells leads to insulin deficiency and hyperglycemia. Current efforts to understand the mechanisms underlying β cell damage in diabetes rely on in vitro-cultured cadaveric islets. However, isolation of these islets involves removal of crucial matrix and vasculature that supports islets in the intact pancreas. Unsurprisingly, these islets demonstrate reduced functionality over time in standard culture conditions, thereby limiting their value for understanding native islet biology. Leveraging a novel, vascularized micro-organ (VMO) approach, we have recapitulated elements of the native pancreas by incorporating isolated human islets within a three-dimensional matrix nourished by living, perfusable blood vessels. Importantly, these islets show long-term viability and maintain robust glucose-stimulated insulin responses. Furthermore, vessel-mediated delivery of immune cells to these tissues provides a model to assess islet-immune cell interactions and subsequent islet killing -- key steps in type 1 diabetes pathogenesis. Together, these results establish the islet-VMO as a novel, ex vivo platform for studying human islet biology in both health and disease.

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“…Biochemical gradients of growth factors, cytokines, and chemokines influence cell migration, tissue phenotype, and angiogenesis in the TME ( 114 ), and can be established, monitored, and perturbed using OOC technologies ( 24 , 114 – 116 ). Emerging methods also enable the manipulation of hypoxia in OOC devices ( 117 , 118 ); this property regulates gene transcription and alters physiological and pathological immunity ( 119 , 120 ). Our group has also pioneered methods to vascularize tissues, including CRC, in OOC devices ( 39 , 103 , 106 , 113 , 121 , 122 ).…”

Section: Organ-on-a-chip Modelsmentioning

confidence: 99%

Advances in Modeling the Immune Microenvironment of Colorectal Cancer

et al. 2021

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Colorectal cancer (CRC) is the third most common cancer and second leading cause of cancer-related death in the US. CRC frequently metastasizes to the liver and these patients have a particularly poor prognosis. The infiltration of immune cells into CRC tumors and liver metastases accurately predicts disease progression and patient survival. Despite the evident influence of immune cells in the CRC tumor microenvironment (TME), efforts to identify immunotherapies for CRC patients have been limited. Here, we argue that preclinical model systems that recapitulate key features of the tumor microenvironment—including tumor, stromal, and immune cells; the extracellular matrix; and the vasculature—are crucial for studies of immunity in the CRC TME and the utility of immunotherapies for CRC patients. We briefly review the discoveries, advantages, and disadvantages of current in vitro and in vivo model systems, including 2D cell culture models, 3D culture systems, murine models, and organ-on-a-chip technologies.

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Quantitative design strategies for fine control of oxygen in microfluidic systems

Abstract: Hypoxia, or low oxygen (O2) tension, is a central feature of important disease processes including wound healing and cancer. Subtle temporal and spatial variations (≤ 1% change) in the concentration...

Cited by 21 publications

References 28 publications

96-Well Oxygen Control Using a 3D-Printed Device

96-Well Oxygen Control Using a 3D-Printed Device

A vascularized 3D model of the human pancreatic islet for ex vivo study of immune cell-islet interaction

Advances in Modeling the Immune Microenvironment of Colorectal Cancer

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