Barrier tissues are critical for the proper functioning of organs as they separate the internal and external environment, protect us against harmful substances, and play an important role in the absorption of nutrients and oxygen. Disruption of barrier integrity in organs such as the intestine, kidney, lung, skin, eye, or the blood-brain barrier is an important hallmark of many human diseases and toxic effects^1-3, and therefore an important readout in (bio)medical research.

Furthermore, to develop new drugs or to assess compound safety, it is critical to understand how barriers function with regard to permeability, absorption, and transport mechanisms in relevant biological systems. For this reason, we need good in vitro models that allow us to mimic the complex barrier tissues of the body, preferably in a user-friendly, high-throughput platform so that these models can be used for pre-clinical toxicity assessment as well as for drug screening.

Learn more about 3D in vitro barrier models and how to easily assess their barrier function in our eBook: Building 3D intestinal permeability models for drug development

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Why the OrganoPlate^® platform is the best option to assess barrier integrity

Barrier function can be assessed using multiple systems or approaches. Even though these offer valuable information about the nature of the barrier, the following limitations should be considered⁵:

• They only measure barrier integrity at one single time-point;
• The application of certain tracer compounds in culture and the use of a physical membrane can affect the barrier integrity read-out;
• The use of chemical dyes renders the tested cells unusable for further experiments.

In order to spur faster advances in barrier integrity research, assays must be better suited for the continuous assessment of in vitro barrier models. Over the last decade, the use of microfluidics-based 3D cell culture systems, also called organ-on-a-chip systems, has rapidly gained popularity. These systems add physiologically relevant cues such as exposure to flow-induced shear stress, mechanical strain, and precise control of gradients. The current microfluidics-based cell culture devices are typically based on single chips yielding single datapoints^6-9. This makes it cumbersome to include dilution series, technical replicates, or controls¹⁰. The OrganoPlate^® 3 lane-40 platform, which is based on a regular 384 well plate format, contains 40 microfluidic chips allowing you to culture 40 miniaturized barrier tissues at the same time. By using the OrganoPlate^®, the need for an artificial filter membrane is obviated by the unique PhaseGuide^TM technology: patterned pinning barriers that allow the culture of perfused epithelial or endothelial tubes directly against an extracellular matrix.

Epithelial models are widely studied in vitro environments and are easy to assess in a laboratory setting. To assess the barrier function of epithelia and endothelia in vitro, electrical measurement of the impedance is the golden standard. One way to measure Transepithelial/Transendothelial Electrical Resistance (TEER) is to correlate the electrical properties of an epithelial or endothelial layer with biological aspects such as cell layer confluency and thickness, tight junction formation, and morphology⁴.

We recently⁴ introduced the OrganoTEER^®, a device engineered to measure barrier function of 3D tissue cultures in the OrganoPlate^®. The OrganoTEER^® is not only an extremely efficient device, but it can also measure a wide range of TEER values at several time points, which makes it a valuable tool to answer research questions regarding transepithelial/transendothelial barrier integrity. We have confirmed increasing TEER values with tubular growth over time and decreasing values in response to toxic compounds⁴. We also showed TEER to be capable of timelapse monitoring in real-time under culture flow conditions and that TEER measurement is significantly more sensitive than a fluorescent reporter leakage assay. The device is revolutionary in terms of its throughput, ease of use, and capability to assess epithelia and endothelia under flow and without the interference of porous membranes. We anticipate its routine use in both academic research and pharmaceutical development.

References:

1. R. Cecchelli , V. Berezowski , S. Lundquist , M. Culot , M. Renftel , M. Dehouck and L. Fenart , Nat. Rev. Drug Discovery, 2007, 6 , 650 —66
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3. M. Wilmer , C. Ng , H. Lanz , P. Vulto , L. Suter-Dick and R. Masereeuw , Trends Biotechnol., 2016, 34 , 156 —170.
4. Nicolas A, Schavemaker F, Kosim K, Kurek D, Haarmans M, Bulst M, et al. High throughput transepithelial electrical resistance (TEER) measurements on perfused membrane-free epithelia. Lab Chip. 2021;21(9):1676-85.
5. B. Srinivasan , A. Kolli , M. Esch , H. Abaci , M. Shuler and J. Hickman , J. Lab. Autom., 2015, 20 , 107 —126.
6. R. Booth and H. Kim , Lab Chip, 2012, 12 , 1784 —1792.
7. L. M. Griep , F. Wolbers , B. De Wagenaar , P. M. Ter Braak , B. B. Weksler , I. A. Romero , P. O. Couraud , I. Vermes , A. D. Van Der Meer and A. Van Den Berg , Biomed. Microdevices, 2013, 15 , 145 —150.
8. O. Y. F. Henry , R. Villenave , M. J. Cronce , W. D. Leineweber , M. A. Benz and D. E. Ingber , Lab Chip, 2017, 17 , 2264 —2271.
9. P. Shah , J. V. Fritz , E. Glaab , M. S. Desai , K. Greenhalgh , A. Frachet , M. Niegowska , M. Estes , C. Jäger , C. Seguin-Devaux , F. Zenhausern and P. Wilmes , Nat. Commun., 2016, 7 , 1 —15.
10. C. Probst , S. Schneider and P. Loskill , Curr. Opin. Biomed. Eng., 2018, 6 , 33 —41.
    

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You might also be interested in:

• [Publication] High throughput transepithelial electrical resistance (TEER) measurements on perfused membrane-free epithelia
• [Poster] The OrganoTEER® - A sensitive TEER measurement platform for high-throughput screening of Organs-on-Chips
• Read more about: The OrganoTEER®