Name: co-culture of living microbiome with microengineered human intestinal villi in a gut-on-a-chip microfluidic device
Uploaded: 2016-08-30T15:00:00
Description: Watch this Scientific Journal Video about Co-culture of Living Microbiome with Microengineered Human Intestinal Villi in a Gut-on-a-Chip Microfluidic Device at JoVE.com

We thank Sri Kosuri (Wyss Institute at Harvard University) for providing the GFP-labeled E. coli strain. This work was supported by the Defense Advanced Research Projects Agency under Cooperative Agreement Number W911NF-12-2-0036, Food and Drug Administration under contract #HHSF223201310079C, and the Wyss Institute for Biologically Inspired Engineering at Harvard University. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Office, Army Research Laboratory, Food and Drug Administration, or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation hereon.

1. Microfabrication of a Gut-on-a-chip Device
Note: The gut-on-a-chip is a microfluidic device made by transparent, gas-permeable silicone polymer (polydimethylsiloxane, PDMS), containing two parallel microchannels (1 mm width x 150 &#181;m height x 1 cm length) separated by a flexible porous (10 &#181;m in pore diameter, 25 &#181;m in spacing pore to pore) PDMS membrane5,9. Fabricate the gut-on-a-chip (Figure 1A, left) following the steps provided.
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Understanding host-microbiome interactions is critical for advancing medicine; however, traditional cell culture models performed in a plastic dish or a static well plate do not support the stable co-culture of human intestinal cells with living gut microbes for more than 1-2 days because microbial cells mostly overgrow the mammalian cells in vitro. The overgrowing microbial population rapidly consumes oxygen and nutrients, subsequently producing excessive amount of metabolic wastes (e.g.,&#160;organic ...

The human intestine harbors a stunningly diverse array of microbial species (&#60;1,000 species) and a tremendous number of microbial cells (10 times more than the human host cells) and genes (100 times more than the human genome)1. These human microbiomes play a key role in metabolizing nutrients and xenobiotics, regulating immune responses, and maintaining intestinal homeostasis2. Not surprisingly, given these diverse functions, the commensal gut microbiome extensively modulates health and disease3. Thus, understanding the role of gut microbiome and host-microbe interactions are of great importance to promote gastrointestinal (GI) health and explore new therapeutics for intestinal disorders4. However, existing in vitro intestine models (e.g., static cultures) restrict host-microbiome co-culture to a short period of time (&#60;1 day) because microbial cells overgrow and compromise intestinal barrier function5. Surrogate animal models (e.g., germ-free6 or genetically engineered mice7) are also not commonly used to study host-gut microbiome crosstalk because the colonization and stable maintenance of human gut microbiome are difficult.
To overcome these challenges, we recently developed a biomimetic human &#34;Gut-on-a-Chip&#34; microphysiological system (Figure 1A, left) to emulate the host-gut microbiome interactions that occur in the living human intestine5,8. The gut-on-a-chip microdevice contains two parallel microfluidic channels separated by a flexible, porous, extracellular matrix (ECM)-coated membrane lined by human intestinal epithelial Caco-2 cells, mimicking the intestinal lumen-capillary tissue interface (Figure 1A, right)9. Vacuum-driven cyclic rhythmical deformations induce physiological mechanical deformations that mimic changes normally induced by peristalsis (Figure 1A, right). Interestingly, when Caco-2 cells are grown in the gut-on-a-chip for more than 100 hr, they spontaneously form three-dimensional (3D) intestinal villi with tight junctions, apical brush borders, proliferative cells limited to basal crypts, mucus production, increased drug metabolizing activity (e.g., cytochrome P450 3A4, CYP3A4), and enhanced glucose reuptake8. In this &#39;germ-free&#39; microenvironment, it was possible to co-culture the probiotic Lactobacillus rhamnosus GG or a therapeutic formation of a probiotic bacterial mixture with host epithelial cells for up to two weeks5,10.
In this study, we describe the detailed protocol to perform host-gut microbiome co-culture in the gut-on-a-chip device for an extended period. In addition, we discuss critical issues and potential challenges to be considered for a broad application of this host-microbiome co-culture protocol.

<table border="0" cellpadding="0" cellspacing="0" width="1454">
	<tbody>
		<tr height="25">
			<td height="25" style="height:25px;width:509px;">Dulbecco&#39;s Modified Eagle Medium (DMEM) containing 25 mM glucose and 25 mM HEPES</td>
			<td style="width:227px;">Gibco</td>
			<td style="width:175px;">10564-011</td>
			<td style="width:544px;">Warm it up at 37&#176;C in a water bath.</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:509px;">Difco Lactobacilli MRS broth</td>
			<td style="width:227px;">BD</td>
			<td style="width:175px;">288120</td>
			<td>Run autoclave at 121&#176;C for 15 min.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:509px;">Poly(dimethylsiloxane)</td>
			<td style="width:227px;">Dow Corning</td>
			<td style="width:175px;">3097358-1004</td>
			<td>15:1 (w/w), PDMS : cureing agent</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:509px;">Caco-2BBE human colorectal carcinoma line</td>
			<td style="width:227px;">Harvard Digestive Disease Center</td>
			<td style="width:175px;"></td>
			<td>Human colorectal adenocarcinoma&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:509px;">Heat-inactivated FBS</td>
			<td style="width:227px;">Gibco</td>
			<td style="width:175px;">10082-147</td>
			<td>20% (v/v) in DMEM</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:509px;">Trypsin/EDTA solution (0.05%)</td>
			<td style="width:227px;">Gibco</td>
			<td style="width:175px;">25300-054</td>
			<td>Warm it up at 37&#8451; in a water bath.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:509px;">Penicillin-streptomycin-glutamine</td>
			<td style="width:227px;">Gibco</td>
			<td style="width:175px;">10378-016</td>
			<td>1/100 dilution in DMEM</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:509px;">4&#8242;,6-Diamidino-2-phenylindole dihydrochloride</td>
			<td style="width:227px;">Molecular Probes</td>
			<td style="width:175px;">D1306</td>
			<td>Nuclei staining</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:509px;">Phalloidin-CF647 conjugate (25 units/mL)</td>
			<td style="width:227px;">Biotium</td>
			<td style="width:175px;">00041</td>
			<td>F-actin staining</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:509px;">Flexcell FX-5000 tension system</td>
			<td style="width:227px;">Flexcell International Corporation</td>
			<td style="width:175px;">FX5K</td>
			<td>Peristalsis-like stretcing motion (10% cell strain, 0.15 Hz frequency)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:509px;">Inverted epifluorescence microscope</td>
			<td style="width:227px;">Zeiss</td>
			<td style="width:175px;">Axio Observer Z1</td>
			<td>Imaging, DIC</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:509px;">Scanning confocal microscope</td>
			<td style="width:227px;">Leica</td>
			<td style="width:175px;">DMI6000</td>
			<td>Imaging, Fluorescence</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:509px;">UVO Cleaner</td>
			<td>Jelight Company Inc</td>
			<td style="width:175px;">342</td>
			<td>Surface activation of the gut-chip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Type I collagen&#160;</td>
			<td style="width:227px;">Gibco</td>
			<td style="width:175px;">A10483-01</td>
			<td>Extracellular matrix component for cell culture into the chip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Matrigel</td>
			<td style="width:227px;">BD</td>
			<td style="width:175px;">354234</td>
			<td>Extracellular matrix component for cell culture into the chip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1 mL disposable syringe</td>
			<td style="width:227px;">BD</td>
			<td style="width:175px;">309628</td>
			<td>Cell and media injection stuff</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">25G5/8 needle</td>
			<td style="width:227px;">BD</td>
			<td style="width:175px;">329651</td>
			<td>Cell and media injection stuff</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Syringe pump</td>
			<td>Braintree Scientific Inc.</td>
			<td style="width:175px;">BS-8000</td>
			<td>Injection equipment into the chip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">VSL#3</td>
			<td>Sigma-Tau Pharmaceuticals</td>
			<td>7-45749-01782-6</td>
			<td>A formulation of 8 different commensal gut microbes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Reinforced Clostridial Medium</td>
			<td style="width:227px;">BD</td>
			<td style="width:175px;">218081</td>
			<td>Anaerobic bacteria culture medium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">GasPak EZ Anaerobe Container System with Indicator</td>
			<td style="width:227px;">BD</td>
			<td style="width:175px;">260001</td>
			<td>Anaerobic gas generating sachet&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">4% paraformaldehyde</td>
			<td>Electron Microscopy Science</td>
			<td style="width:175px;">157-4-100</td>
			<td>Fixing the cells for staining</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Triton X-100</td>
			<td style="width:227px;">Sigma-Aldrich</td>
			<td style="width:175px;">T8787</td>
			<td>Permeabilizing the cells</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bovine serum albumin</td>
			<td style="width:227px;">Sigma-Aldrich</td>
			<td style="width:175px;">A7030</td>
			<td>Blocking agent for staining of the cells</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Corona treater</td>
			<td>Electro-Technic Products</td>
			<td>BD-20AC</td>
			<td>Plasma generator for fabrication of the chip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:509px;">Steriflip&#160;</td>
			<td style="width:227px;">Millipore</td>
			<td style="width:175px;">SE1M003M00</td>
			<td>Degasing the complete culture medium</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:509px;">Disposable hemocytometer</td>
			<td style="width:227px;">iNCYTO</td>
			<td style="width:175px;">DHC-N01</td>
			<td>For manual cell counting</td>
		</tr>
	</tbody>
</table>

co-culture of living microbiome with microengineered human intestinal villi in a gut-on-a-chip microfluidic device

Here, we describe a protocol to perform long-term co-culture of multi-species human gut microbiome with microengineered intestinal villi in a human gut-on-a-chip microphysiological device. We recapitulate the intestinal lumen-capillary tissue interface in a microfluidic device, where physiological mechanical deformations and fluid shear flow are constantly applied to mimic peristalsis. In the lumen microchannel, human intestinal epithelial Caco-2 cells are cultured to form a &#39;germ-free&#39; villus epithelium and regenerate small intestinal villi. Pre-cultured microbial cells are inoculated into the lumen side to establish a host-microbe ecosystem. After microbial cells adhere to the apical surface of the villi, fluid flow and mechanical deformations are resumed to produce a steady-state microenvironment in which fresh culture medium is constantly supplied and unbound bacteria (as well as bacterial wastes) are continuously removed. After extended co-culture from days to weeks, multiple microcolonies are found to be randomly located between the villi, and both microbial and epithelial cells remain viable and functional for at least one week in culture. Our co-culture protocol can be adapted to provide a versatile platform for other host-microbiome ecosystems that can be found in various human organs, which may facilitate in vitro study of the role of human microbiome in orchestrating health and disease.

To emulate the human intestinal host-microbiome ecosystem in vitro, it is necessary to develop an experimental protocol to reconstitute the stable long-term co-culture of gut bacteria and human intestinal epithelial cells under physiological conditions such as peristalsis-like mechanics and fluid flow. Here, we utilize a biomimetic gut-on-a-chip microdevice (Figure 1A) to co-culture living microbial cells in direct contact with living human vill...

Watch this Scientific Journal Video about Co-culture of Living Microbiome with Microengineered Human Intestinal Villi in a Gut-on-a-Chip Microfluidic Device at JoVE.com

Co-culture of Living Microbiome with Microengineered Human Intestinal Villi in a Gut-on-a-Chip Microfluidic Device

We describe an in vitro protocol to co-culture gut microbiome and intestinal villi for an extended period using a human gut-on-a-chip microphysiological system.

Here, we describe a protocol to perform long-term co-culture of multi-species human gut microbiome with microengineered intestinal villi in a human ...

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