Model‐based analysis and design of a microchannel reactor for tissue engineering

Mehta, Khamir; Linderman, Jennifer J.

doi:10.1002/bit.20857

Cited by 50 publications

(51 citation statements)

References 33 publications

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“…There have been numerous reports of applying plug flow and surface reaction-type solutions to microchannels, which involves solving a system of partial differential equations for fluid flow and mass transfer (6,15,16). However, simulations limited to bulk concentration effects cannot capture differences in local concentration created by underlying cellular activities.…”

Section: Discussionmentioning

confidence: 99%

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Predictive microfluidic control of regulatory ligand trajectories in individual pluripotent cells

Moledina

Clarke

Oskooei

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Local (cell-level) signaling environments, regulated by autocrine and paracrine signaling, and modulated by cell organization, are hypothesized to be fundamental stem cell fate control mechanisms used during development. It has, however, been challenging to demonstrate the impact of cell-level organization on stem cell fate control and to relate stem cell fate outcomes to autocrine and paracrine signaling. We address this fundamental problem using a combined in silico and experimental approach in which we directly manipulate, using laminar fluid flow, the local impact of endogenously secreted gp130-activating ligands and their activation of signal transducer and activator of transcription3 (STAT3) signaling in mouse embryonic stem cells (mESC). Our model analysis predicted that flow-dependent changes in autocrine and paracrine ligand binding would impact heterogeneity in cell-and colony-level STAT3 signaling activation and cause a gradient of cell fate determination along the direction of flow. Interestingly, analysis also predicted that local cell density would be inversely proportional to the degree to which endogenous secretion contributed to cell fate determination. Experimental validation using functional activation of STAT3 by secreted factors under microfluidic perfusion culture demonstrated that STAT3 activation and consequently mESC fate were manipulable by flow rate, position in the flow field, and local cell organization. As a unique demonstration of how quantitative control of autocrine and paracrine signaling can be integrated with spatial organization to elicit higher order cell fate effects, this work provides a general template to investigate organizing principles due to secreted factors.Brownian dynamics simulation | embryonic stem cells | leukemia inhibitory factor | cell fate control | cell heterogeneity T he developing embryo uses many spatially and temporally regulated mechanisms of signal propagation, including autocrine, paracrine, and extracellular matrix-mediated signals to control the proliferation and differentiation of progenitor cells. Based on our understanding of in vivo development, in vitro strategies attempt to mimic developmental mechanisms and establish artificial environments or niches that promote specific cell fates. Despite considerable progress in our ability to control pluripotent cell fate in vitro, significant variability and heterogeneity in differentiation protocols exist. One reason for this is thought to be our inability to mimic the temporally and spatially diverse signaling environments that occur in the embryo. Herein we use mouse embryonic stem cells (mESC) cultures as a model system to reveal a role for autocrine and paracrine signaling in cell fate control and to demonstrate how endogenous signaling and cell organization interact to create higher order local cellular environments, or niches.Mouse ESC cultures normally include the soluble interleukin-6 (IL-6) ligand family member leukemia inhibitory factor (LIF). IL-6 ligands such as LIF signal through the Jan...

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Section: Discussionmentioning

confidence: 99%

“…1B). The use of a stochastic approach here is unique, because models of perfusion culture to date have characterized ligand movements using deterministic mass transport theory (6,7). While informative, these models treat cultures as uniform surfaces with a single value representing ligand uptake by cells.…”

Section: Modelmentioning

confidence: 99%

Predictive microfluidic control of regulatory ligand trajectories in individual pluripotent cells

Moledina

Clarke

Oskooei

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…RTDP was well tolerated by the myoblasts within the bioreactor, as evidenced by cytotoxic and phototoxic studies done using trypan blue ͑Sigma-Aldrich͒. A published partial differential equation ͑PDE͒ model describing oxygen diffusion, convection, and uptake by cells within the device was developed and solved using 11 FEMLAB ͑Consol AB Inc.͒.…”

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confidence: 99%

“…Modeling results indicate that media recycling might be beneficial to retain growth factor͑s͒ secreted by cells; 11 such a scheme will potentially affect oxygen levels, which can be tracked almost in real time due to fast data acquisition ͑Ͻ10 s͒ by the FLIM approach. All these endeavors are ultimately aimed at controlling long-term cellular responses ͑such as differentiation͒ in PDMS microbioreactors.…”

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confidence: 99%

Optical imaging in microfluidic bioreactors enables oxygen monitoring for continuous cell culture

Sud

Mehta

et al. 2006

J. Biomed. Opt.

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Abstract. For the first time, a fluorescence lifetime calibration method for an oxygen-sensitive dye ruthenium tris͑2 ,2Ј-dipyridyl͒ dichloride hexahydrate ͑RTDP͒ is applied to image oxygen levels in poly͑dimethyl siloxane͒ ͑PDMS͒ bioreactors containing living C2C12 mouse myoblasts. PDMS microsystems are broadly used in bioengineering applications due to their biocompatibility and ease of handling. For these systems, oxygen concentrations are of significance and are likely to play an important role in cell behavior and gene expression. Fluorescence lifetime imaging microscopy ͑FLIM͒ bases image contrast on fluorophore excited state lifetimes, which reflect local biochemistry. Unique attributes of the widefield, timedomain FLIM system include tunable excitation ͑337.1 to 960 nm͒, large temporal dynamic range ͑Ն600 ps͒, high spatial resolution ͑1.4 m͒, calibrated detection ͑0 to 300± 8 M of oxygen͒, and rapid data acquisition and processing times ͑10 s͒. Oxygen levels decrease with increasing cell densities and are consistent with model outcomes obtained by simulating bioreactor oxygen diffusion and cell proliferation. In single bioreactor loops, FLIM detects spatial heterogeneity in oxygen levels with variations as high as 20%. The fluorescence lifetime-based imaging approach we describe avoids intensity-based artifacts ͑in-cluding photobleaching and concentration variations͒ and provides a technique with high spatial discrimination for oxygen monitoring in continuous cell culture systems. Microfluidic devices have promising applications in cellbased assays and microscale tissue engineering, where spatiotemporal conditions are readily manipulated. Recently, poly͑dimethyl siloxane͒-͑PDMS͒-based microfluidic systems have been developed as biocompatible and rapidly prototyped systems for microscale-cell culture. For example, cells could be seeded and cultured successfully under continually perfused conditions to achieve an extracellular fluid-to-cell ͑vol-ume͒ ratio close to the physiological value 1 of 0.5. This small ratio facilitates heterogeneous chemical distribution, which may be critical in specifying cell fate in developing tissues. It is hence of great interest to quantitatively and with minimal perturbation characterize components ͑e.g., mitogens, nutrients, oxygen͒ in microfluidic bioreactors that influence cellular responses.Oxygen in cell cultures influences cell signaling, growth, differentiation, and death.1 PDMS bioreactors are popular due to their high diffusivity of oxygen, which has been repeatedly demonstrated.2 It has been observed, 3 however, that the diffusivity of PDMS can vary, depending on protein adsorption ͑e.g., when cells are cultured͒ or surface modification ͑e.g., plasma oxidization for bioreactors͒. It is hypothesized that this variability in PDMS permeability, along with cellular uptake and culture media perfusion, can affect spatial variations in oxygen within PDMS bioreactors.Optical measurements of oxygen sensitive agents have advantages over more traditional, electrode-based app...

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“…The applications of this area are too vast and some of the applications are belongs to cartelistic reactors [2,3] , Tissue Engineering [4] , Multiphase mixing and reaction [5] , Blood Flow and the drug reaction [6] , highthroughput screening in drug development [9,10] , bio-analyses [11] , examination and manipulation of samples consisting of a single cell [12,13] , and also in efficient heat sinks [8] . But one of the main applications of this field is the extraction process.…”

Section: Recently the Area Microfluidics Is Related To Chemicalmentioning

confidence: 99%

Numerical investigation of Phenol Extraction using Liquid-Liquid Stratified Flow in a T shaped Micro-channel

Antony¹,

Arun²,

Anu³

et al. 2012

IJCA

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Model‐based analysis and design of a microchannel reactor for tissue engineering

Cited by 50 publications

References 33 publications

Predictive microfluidic control of regulatory ligand trajectories in individual pluripotent cells

Predictive microfluidic control of regulatory ligand trajectories in individual pluripotent cells

Optical imaging in microfluidic bioreactors enables oxygen monitoring for continuous cell culture

Numerical investigation of Phenol Extraction using Liquid-Liquid Stratified Flow in a T shaped Micro-channel

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