Albers, Hugo J.

Eijkel, Jan

Gümüscü, Burcu

van den Berg, Albert

van der Meer, Andries D.

English

This paper reports a novel approach to build large arrays of cell-laden hydrogel microcompartments with well-controlled fluid flow to mimic the gut environment. Human intestinal epithelial cells (Caco-2) that were cultured in ~500 discontinuous compartments spontaneously grew into 3D folds on day 3. Mimicking interaction between intestinal eptithelial cells and intestinal bacteria was demonstrated in a long-term co-culture of E. coli adhered to Caco-2, the viability of which remained &gt;70%. Also, different compartment geometries with large and small hydrogel interfaces were found to affect proliferation and cell spreading of Caco-2

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A GUT-ON-A-CHIP STUDY: ENABLING ON-DEMAND MANIPULATION OF THE OUTER CELL MICROENVIRONMENT IN A MULTICOMPARTMENTAL 3D CULTURE ARRAY Burcu Gumuscu1,*, Hugo J. Albers1,2, Albert van den Berg1, Jan Eijkel1, and  Andries D. van der Meer2,* 1BIOS Lab-on-a-Chip Group, MESA+ Institute for Nanotechnology, MIRA Institute for Biomedical  Technology and Technical Medicine, University of Twente, Enschede, The Netherlands 2Applied Stem Cell Technologies Group, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands ABSTRACT This paper reports a novel approach to build large arrays of cell-laden hydrogel microcompartments with well-controlled fluid flow to mimic the gut environment. Human intestinal epithelial cells (Caco-2) that were cultured in ~500 discontinuous compartments spontaneously grew into 3D folds on day 3. Mimicking interaction between intestinal eptithelial cells and intestinal bacteria was demonstrated in a long-term co-culture of E. coli adhered to Caco-2, the viability of which remained >70%. Also, different compartment geometries with large and small hydrogel interfaces were found to affect proliferation and cell spreading of Caco-2.  KEYWORDS: Gut-on-chip, microfluidics, 3D culture array  INTRODUCTION 3D spheroid and organoid tissue culture models are becoming increasingly popular in biomedical science and drug screening [1-2]. One of the most high-profile examples is in vitro culture of gut organoid cultures from sin-gle adult stem cells [3]. However, gut organoid cultures have typical shortcomings: displaying size heterogeneity, limited overall tissue shape (folded spheres), and short co-culturing time with bacteria [4]. The introduction of the parallelized microculture platform and the proof-of-concept data provided here demonstrate an alternative ap-proach that can address the aforementioned shortcomings in future studies.  EXPERIMENTAL Microchips were fabricated from polydimethylsiloxane (PDMS) using standard soft lithography techniques.  The microchips contain pillars, capillary barriers, microchannels, and reservoirs. Microchannel and capillary bar-rier heights were 75 and 7.5 µm, respectively. Fig.1 shows an assembled microchip. A mixture of collagen (0.3%) and Caco-2 (7·106 cells/ml) was patterned in the microchips by capillary pinning [5]. DMEM Glutamax supple-mented with 20%(v/v) FBS, and 100 units/ml of pen/strep was pumped into the microchips at a constant flow rate (300 µl/h). To study cell-bacteria interactions, a culture medium–E. coli (1.9·107cells/ml) mixture was injected in-to the microchips starting on the 8th day of culture for 36 h. Both fluid flow and static conditions were compared. Also, Caco-2 were cultured in trapezoid and rectangular compartments for 6 days under continuous perfusion. RESULTS AND DISCUSSION Caco-2 started to spontaneously grow into 3D folds on day 2-3 of culture (Fig.2a-h). After day 8, cells filled the compartments completely and started migrating towards microchannels (Fig.1d). Based on observations using confocal microscope in Fig. 2i-j, after 6 days of culturing Caco-2 formed tubular structures with 3D folds inside, Figure 1: Overview of microfluidic chip design and the method of patterning hydrogels by capillary pinning. (a) A photograph of the microchip with attached tubing. (b) Schematic isometric view of the microchip with hydrogel patterns. (c) A zoomed-in sche-matic illustration of the capillary barriers, PDMS pillars, and hydrogel compartments. The height of capillary barriers is 1/4 of the microchannel height. The compartments are 200x500 µm. (d) Caco-2 cells grown under 300 µl/h flow rate, on day 8.  (a)12 mm(b)MicrochannelsReservoirPDMS pillar Capillary barrierHydrogel compartment(c) (d)250 µm978-0-692-94183-6/µTAS 2017/$20©17CBMS-0001 1013 21st International Conference on MiniaturizedSystems for Chemistry and Life SciencesOctober 22-26, 2017, Savannah, Georgia, USAresembling a lumen structure. Different compartment geometries with large and small hydrogel interfaces led to differences in proliferation and in cell spreading (Fig.2). Microfluidic perfusability prevented unrestrained over-proliferation of bacteria in the microchip while Caco-2 remained accessible by the bacterial cells in the fluidic culture. Caco-2 showed no indication of cell death at 300 µl/h flow rate with a suspension of E. coli (Fig. 3b). Similar viability was observed when E. coli was absent (Fig. 3a, c). When Caco-2 were co-cultured with E.coli under static conditions, approximately 30% of Caco-2 had died after 36 h (Fig. 3d). CONCLUSION Enabling high-throughput culturing in a microfluidic environment, our approach has the potential to be used for building next-generation organotypic in vitro plat-forms, and creating separate 3D microenvironments, where a gradient of different metabolites can be applied to study tissue functions, drug screening, and perhaps organ-on-chip assemblies.   ACKNOWLEDGEMENTS This work was funded by the Dutch network for Nanotechnology NanoNext NL in the subprogram “Nanoflu-idics for Lab-on-a-chip”.   REFERENCES [1]  A. Ranga, N. Gjorevski, M.P. Lutolf, “Drug discovery through stem cell-based organoid models,” Adv. Drug Deliv. Rev., 69, 19-28, 2014. [2]  H. Clevers, “Modeling development and disease with organoids,” Cell, 165, 1586-1597, 2016. [3]  T. Sato, R.G. Vries, H.J. Snippert, M. Van de Wetering, N. Barker, D.E. Stange, J.H. Van Es, A. Abo, P. Kujala, P.J. Peters, H. Clevers, “Single Lgr5 stem cells build crypt villus structures in vitro without a mesenchymal niche,” Nature, 459, 262-265, 2009. [4]  Y.G. Zhang, S. Wu, Y. Xia, J. Sun, “Salmonella-infected crypt-derived intestinal organoid culture system for host–bacterial interactions,” Physiol. Rep., 2, e12147, 2014. [5]  B. Gumuscu, A. van den Berg, J. C. T. Eijkel, “Large scale patterning of hydrogel microarrays using capillary pinning,” Lab Chip, 15, 664-667, 2015.  CONTACT *Burcu Gumuscu, b.gumuscu@utwente.nl; Andries D. van der Meer, a.d.vandermeer@utwente.nl. Figure 2: Top-view phase contrast images of Caco-2 cells in the microchip in different days of cell culture. The results are shown for the microchips operated (a-b) under static conditions and (d-h) under 300 µl/h flow rate, where (d-e) in rectangular, (g-h) in trap-ezoid shaped compartments. Confocal microscopy image of the Caco-2 cells grown under 300 µl/h flow rate on day 8 in (i) rec-tangular shaped (j) trapezoid shaped compartments. Dashed lines denote pillar boundaries, red dashed line shows location of y-z cross-section (inset right). Scale bars are 250 µm. Microchip(Static) (a) Day 2 (b) Day 6Microchip(300 µl h-1flow rate) PDMS pillarCaco-2 cells(d) Day 2 (e) Day 6(g) Day 2 (h) Day 6Microchip(300 µl h-1flow rate) (i)(j)Cell nucleiF-actinFigure 3: Top-view phase contrast microscopy images of live/dead assay bacteria co-culture operated (a) under 300 µh/l flow rate without E. coli cells, (b) under 300 µl/h flow rate with E. coli cells, (c) without fluid flow and without E. coli cells (d) without fluid flow with E. coli cells. The nuclei of Caco-2 cells were stained with DAPI (blue). Alive Caco-2 cells are shown in green and dead Caco-2 cells are shown in red colors. In Fig.s b and d, the dark cloudy appearance in the microchannels and the compartments is caused by E. coli colonies. Scale bar is 250 µm.  (d)(a)Co-cultured with E. coli300 µl h-1 flow rateCultured without E. coliStatic conditions(c)(b)PDMS pillar Dead cellsCell nuclei Living cells1014

A gut-on-a-chip study:Enabling on-demand manipulation of the outer cell microenvironment in a multicompartmental 3D culture array

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A gut-on-a-chip study:Enabling on-demand manipulation of the outer cell microenvironment in a multicompartmental 3D culture array

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