Microfluidic Device for Recreating a Tumor Microenvironment &lt;em&gt;in Vitro&lt;/em&gt;

Toley, Bhushan J.; Ganz, Dan E.; Walsh, Colin; Forbes, Neil S.

doi:10.3791/2425

Cited by 7 publications

(9 citation statements)

References 8 publications

(2 reference statements)

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“…Bacterial penetration into cell masses was measured in a tumor-on-achip microfluidic device ( Fig. 1B) that mimics tissue bordering blood vessels in tumors (Toley et al, 2011;Walsh et al, 2009). The device was formed by soft lithography as described previously (Toley et al, 2011;Walsh et al, 2009).…”

Section: Measurement Of Bacterial Penetration Into Tumor Cell Massesmentioning

confidence: 99%

Persistent enhancement of bacterial motility increases tumor penetration

Thornlow

Brackett

Gigas

et al. 2015

Biotech & Bioengineering

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Motile bacteria can overcome the transport limitations that hinder many cancer therapies. Active bacteria can penetrate through tissue to deliver treatment to resistant tumor regions. Bacterial therapy has had limited success, however, because this motility is heterogeneous and within a population many individuals are non-motile. In human trials, heterogeneity led to poor dispersion and incomplete tumor colonization. To solve these problems, a swarm-plate selection method was developed to increase swimming velocity. Video microscopy was used to measure the velocity distribution of selected bacteria and a microfluidic tumor-on-a-chip device was used to measure penetration through tumor cell masses. Selection on swarm plates increased average velocity four fold, from 4.9 to 18.7 μm/sec (P<0.05) and decreased the number of non-motile individuals from 51 to 3% (P<0.05). The selected phenotype was both robust and stable. Repeating the selection process consistently increased velocity and eliminated non-motile individuals. When selected strains were cryopreserved and subcultured for 30.1 doublings, the high-motility phenotype was preserved. In the microfluidic device, selected Salmonella penetrated deeper into cell masses than unselected controls. By ten hours after inoculation, control bacteria accumulated in the front 30% of cell masses, closest to the flow channel. In contrast, selected Salmonella accumulated in the back 30% of cell masses, farthest from the channel. Selection increased the average penetration distance from 150 to 400 μm (P<0.05). This technique provides a simple and rapid method to generate high-motility Salmonella that have increased penetration and potential for greater tumor dispersion and clinical efficacy.

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Section: Measurement Of Bacterial Penetration Into Tumor Cell Massesmentioning

confidence: 99%

Persistent enhancement of bacterial motility increases tumor penetration

Thornlow

Brackett

Gigas

et al. 2015

Biotech & Bioengineering

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“…In tissue in a microfluidic device (31), QS Salmonella only expressed GFP in high-density colonies ( Fig. 2 C and D).…”

Section: Resultsmentioning

confidence: 99%

Quorum-sensing Salmonella selectively trigger protein expression within tumors

Swofford

Dessel

Forbes

2015

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

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106

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Salmonella that secrete anticancer proteins have the potential to eliminate tumors, but nonspecific expression causes damage to healthy tissue. We hypothesize that Salmonella, integrated with a density-dependent switch, would only express proteins in tightly packed colonies within tumors. To test this hypothesis, we cloned the lux quorum-sensing (QS) system and a GFP reporter into nonpathogenic Salmonella. Fluorescence and bacterial density were measured in culture and in a tumor-on-a-chip device to determine the critical density necessary to initiate expression. QS Salmonella were injected into 4T1 tumor-bearing mice to quantify GFP expression in vivo using immunofluorescence. At densities below 0.6 × 1010 cfu/g in tumors, less than 3% of QS Salmonella expressed GFP. Above densities of 4.2 × 1010 cfu/g, QS Salmonella had similar expression levels to constitutive controls. GFP expression by QS colonies was dependent upon the distance to neighboring bacteria. No colonies expressed GFP when the average distance to neighbors was greater than 155 µm. Calculations of autoinducer concentrations showed that expression was sigmoidally dependent on density and inversely dependent on average radial distance. Based on bacterial counts from excised tissue, the liver density (0.0079 × 1010 cfu/g) was less than the critical density (0.11 × 1010 cfu/g) necessary to initiate expression. QS Salmonella are a promising tool for cancer treatment that will target drugs to tumors while preventing damage to healthy tissue.

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“…Humidity and pH was maintained by flowing 25mM HEPES buffered DMEM at 3 μl/min. Devices were constructed using standard soft lithography techniques as described previously 18, 20 . Molds were made by selectively exposing SU-8 ( MicroChem , Newton, MA) coated wafers to UV light through photomasks to produce positive-relief features.…”

Section: Methodsmentioning

confidence: 99%

“…Several different devices for forming 3D cancer cell masses (hereafter referred to as tissues) in continuously perfused microfluidic devices have been described 15-17 . In our laboratory, we previously designed a device to grow cancer tissues in a rectangular geometry that forms one-dimensional chemical gradients and can be continuously monitored in time and space under a microscope 18-20 . Because of its geometry, transport can be described with a simple one-dimensional mathematical model, which enables quantification of the diffusion and binding rates.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic technique to measure intratumoral transport and calculate drug efficacy shows that binding is essential for doxorubicin and release hampers Doxil

et al. 2013

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Intratumoral transport and binding are important mechanisms that determine the efficacy of cancer drugs. Current drug screening methods rely heavily on monolayers of cancer cells, which overlook the contribution of tissue-level transport and binding. To quantify these factors, we developed a method that couples an in vitro, drug-delivery device containing a three-dimensional cell mass and a mathematical model of drug diffusion, binding to DNA, release from carriers, and clearance. Spheroids derived from LS174T human colon carcinoma cells were inserted into rectangular chambers to form rectangular cell masses (tissue) and subjected to continuous medium perfusion. To simulate drug delivery and clearance, the tissues were treated with doxorubicin followed by drug-free medium. To evaluate the effect of liposome encapsulation, tissues were treated with liposome-encapsulated doxorubicin (Doxil). Spatiotemporal dynamics of drug distribution and apoptosis was measured by fluorescence microscopy. The diffusivity and DNA binding constant of doxorubicin were determined by fitting experimental data to the mathematical model. Results show that an ideal combination of diffusivity, binding constant, clearance rate, and cytotoxicity contribute to the high therapeutic efficacy of doxorubicin. There was no detectable release of doxorubicin from Doxil in the tissues. The rate of doxorubicin release, evaluated by fitting experimental data to the mathematical model, was below therapeutically effective levels. These results show that despite enhanced systemic circulation obtained by liposome encapsulation, the therapeutic effect of Doxil is limited by slow intratumoral drug release. The experimental and computational methods developed here to calculate drug efficacy provide mechanisms to explain poor performance of drug candidates, and enable design of more successful cancer drugs.

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Microfluidic Device for Recreating a Tumor Microenvironment <em>in Vitro</em>

Cited by 7 publications

References 8 publications

Persistent enhancement of bacterial motility increases tumor penetration

Persistent enhancement of bacterial motility increases tumor penetration

Quorum-sensing Salmonella selectively trigger protein expression within tumors

Microfluidic technique to measure intratumoral transport and calculate drug efficacy shows that binding is essential for doxorubicin and release hampers Doxil

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