This study was made in collaboration with BASF Beauty Care Solutions. Ms. Charlie Colin-Pierre is a BASF /CNRS-funded PhD fellow.
We wish to thank Mr. Mehdi Sellami for the conception of the 3D-printed inserts.

NOTE: The 3D inserts (Figure 1A) are commercially procured and are printed using a photopolymer resin that is biocompatible with cell culture and autoclaving (see the Table of Materials). In this section, a detailed protocol to establish the co-culture model by inserts is described (see Figure 1B). Some examples of applications are also provided.
1. Placement of the sterilized insert in the 6-well plates
<ol>
	<li>Mix the two components provided in the kit (see Table of Materials), food silicon (reagent A) and catalyst (reagent B), in a ratio of 10:1 (v/v) according to the manufacturer&#39;s instructions. (Figure 1Ba). Use a 70% ethanol sterilized spatula to mix the two components. 
	NOTE: The volume of the silicon mixture to be prepared depends on the number of inserts to be fixed. An excess of catalyst can result in the silicon mixture solidifying too fast.</li>
	<li>Apply the inserts on the silicon mix with tweezers so that the mixture is homogeneously distributed at the bottom edge of the inserts (Figure 1Bb). Place the inserts into the wells of a 6-well plate and apply gentle pressure on the inserts to ensure that the inserts are in close contact with the plate to avoid any leakage of the cell culture medium (Figure 1Bc).</li>
	<li>Put the plate at 37 &#730;C to support the solidification process of the silicon for 1 h. 
	NOTE: The time of solidification depends on the quantity of catalyst that has been added.</li>
	<li>After solidification, sterilize the plates with the inserts by immersing them in a 70% ethanol bath for 30 min to 1 h.</li>
	<li>Discard the alcohol by pipetting and let the plate dry (lid open) overnight in a cell culture hood. 
	&#8203;NOTE: The alcohol must be fully evaporated before performing the next step to avoid cell fixation and toxicity. The ready-to-use plate containing the inserts can be stored for several days before use in dry and sterile conditions at room temperature.</li>
</ol>
2. Coatings such as poly-L-lysine, or poly-HEMA (Optional step)
NOTE: Coating is not performed in this experiment, and the steps are provided to inform regarding the possibility of coating the inserts.
<ol>
	<li>Prepare the coating solution according to the manufacturer&#39;s instructions.</li>
	<li>Consider a volume of 200-400 &#181;L for the largest compartments and a volume of 50-100 &#181;L for the smallest compartments for the coating of the insert. Add the coating solution to the individual compartments.</li>
	<li>Let the coating dry as indicated by the manufacturer under sterile conditions.</li>
</ol>
3. Seeding of the cells
<ol>
	<li>Culture the keratinocytes of the outer root sheath (KORS) and human dermal microvascular endothelial cells (HDMECs) as recommended by the manufacturer. Prepare the cell suspension once the cells reach confluency.
	<ol>
		<li>Discard the medium from the flasks and add 5 mL of trypsin to detach the cells (see Table of Materials).</li>
		<li>Place the flask containing the KORS at 37 &#176;C with 5% CO2 for 5 min. Incubate the flask containing the HDMECs for 5 min at room temperature.</li>
		<li>Mix the trypsin solution containing the KORS with 5 mL of mesenchymal stem cell medium (MSCM) supplemented with 5% fetal bovine serum (FBS) and growth factors (basal medium with supplement kit, see Table of Materials). Mix the trypsin solution containing the HDMECs with 5 mL of endothelial cell medium (ECM) supplemented with 5% FBS and growth factors (see Table of Materials).</li>
		<li>Transfer the cells into a 15 mL of sterile conical tube. Centrifuge the KORS and HDMEC suspensions at 200 x g for 5 min at room temperature.</li>
		<li>Discard the supernatant and resuspend the cells in 2 mL of the respective medium.</li>
		<li>Mix 10 &#181;L of the cell suspension with 10 &#181;L of trypan blue dye (see Table of Materials).</li>
		<li>Add 10 &#181;L of the mix into the chamber of the counting slide.</li>
		<li>Insert the counting slide into the cell counting system (see Table of Materials) and detect the cell number and the viability.</li>
		<li>Prepare the cell suspension at a concentration of 0.5 x 105 cells/mL in the respective medium. 
		NOTE: If the different cell types require different times of adherence and/or to reach the ideal confluency, the cell seeding can be made at different time points according to the cell types.</li>
	</ol>
	</li>
	<li>Distribute 800 &#181;L to 1 mL of the cell suspension into the individual large compartments and 100-150 &#181;L into the individual small compartments with a pipette.
	<ol>
		<li>Seed the KORS at 1 x 105 cells/mL in MSCM supplemented with 5% FBS and growth factors in one of the big compartments.</li>
		<li>Seed HDMEC in ECM supplemented with 5% FBS and growth factors at 2.5 x 103 cells/mL in the small compartments and at 1.25 x 105 cells/mL in the other big compartment. 
		NOTE: The proliferation assay can be performed in the small compartments, and the migration and viability assays can be performed in the big compartments. The concentration of the cells seeded has been optimized according to the manufacturer&#39;s recommendations. This concentration allows for good viability of the cells after 24-48 h of incubation.</li>
	</ol>
	</li>
	<li>Place the cell culture plate at 37 &#730;C with 5% CO2 or under the usual conditions to allow for cell adhesion and/or maturation. 
	NOTE: Incubate the cells for 24-48 h without changing the media. If needed, the medium of the compartments can be changed independently.</li>
</ol>
4. Implementation of the co-culture (&#160;Figure 1Bd)
NOTE: The implementation of the co-culture corresponds to the time when the common medium is added. The addition of a unique medium for all the cell types in the different compartments provides the possibility of paracrine communication between the cells due to the presence of communication windows (ovoid holes in the walls of the 3D-printed inserts). To implement the co-culture, follow steps 4.1-4.3.
<ol>
	<li>Empty the culture media of the different compartments of the inserts using a pipette. In case of a 3D spheroid cell culture, discard the medium very gently.</li>
	<li>Rinse the cells with 1 mL of 37 &#176;C warm PBS in the big compartments and 200 &#181;L of 37 &#176;C warm PBS in the small compartments. Ensure gentle washing to not detach the cells.</li>
	<li>Add 3 mL of a common medium selected to be compatible for all cell types. 
	NOTE: In this study, the basal ECM (without FBS and growth factors) is used. Make sure that the medium covers all the compartments (level above the communication windows [ovoid holes in the walls], as shown in Figure 1A).</li>
	<li>Place the plate containing the co-cultures at 37 &#730;C with 5% CO2 for 24-48 h.</li>
</ol>
5. Cell observation, counting, and scraping
<ol>
	<li>Observe the morphology and count the cell number of the different compartments during the experiment under an optical microscope after 24-48 h of incubation. 
	NOTE: The expected number of cells depends on the cell types used (size, morphology, etc.) and on the compartment size. In this experiment, between 0.5 x 106-1 x 106 KORS/mL and between 0.25 x 106-0.75 x 106 HDMECs/mL are counted in the big compartments.</li>
	<li>Detach the cells using trypsin for cell suspension counting. 
	NOTE: For the cell detachment solution, consider a volume of 100-500 &#181;L for the largest compartments and a volume of 10-50 &#181;L for the smallest compartments.</li>
	<li>Check the viability by using trypan blue staining (see steps 3.1.6-3.1.8).</li>
</ol>
6. Insert cleaning for recycling
<ol>
	<li>Remove the inserts from the 6-well plate at the end of the experiment by a slight twist (Figure 1Be).</li>
	<li>Remove the silicon from the inserts by pulling it off. If necessary, use a spatula to remove the remaining silicon stuck to the walls of the inserts (Figure 1Bf).</li>
	<li>Wash the inserts with conventional cell culture detergents and cleaning materials (example provided in the Table of Materials).</li>
	<li>Sterilize the inserts for future use in an autoclave (solid cycle, 121 &#730;C for 20 min) or by immersing them in a 70% ethanol bath for 1 h. 
	&#8203;NOTE: From this step, two examples of possible assays (proliferation and migration assays) are described using the 3D-printed inserts (Figure 1Bd).</li>
</ol>
7. Cell proliferation assay - WST-1 assay
<ol>
	<li>Follow steps 1-3.1 to culture the cells. 
	NOTE: Follow the step in this section to implement the co-culture system in order to investigate the effect of the KORS secretome on HDMEC proliferation. KORS cells are used to compare the data published previously8.
	<ol>
		<li>Seed the KORS at 1 x 105 cells/mL in mesenchymal stem cell medium (MSCM) supplemented with 5% FBS and growth factors in the big compartments.</li>
		<li>Place the cell culture plate at 37 &#730;C with 5% CO2 for 24 h.</li>
		<li>Seed the HDMECs in endothelial cell medium (ECM) supplemented with 5% FBS and growth factors at 2.5 x 103 cells/mL in the small compartments.</li>
		<li>Place the cell culture plate at 37 &#176;C with 5% CO2 for 24-48 h.</li>
		<li>Discard the media from all the compartments and implement the co-culture system by the addition of 3 mL of non-supplemented basal ECM (common cell culture medium for all the compartments of the 3D-printed inserts).</li>
	</ol>
	</li>
	<li>Dilute WST-1 in the ECM common cell culture medium (1:10 final dilution) to prepare the WST-1 solution. 
	&#8203;NOTE: For the volume of WST-1 solution, prepare at least 500 &#181;L of extra solution for the blank.</li>
	<li>Discard the cell culture medium from the insert by pipetting.</li>
	<li>Add the WST-1 solution to the selected compartments (150 &#181;L for the small compartments and 600 &#181;L for the big compartments). Put the plate at 37 &#730;C with 5% CO2.</li>
	<li>After the optimal 30 min cell incubation time, transfer 100 &#181;L of the incubation medium from each condition on a 96-well plate.</li>
	<li>Assess the colorimetric reaction using a microplate reader between 420 nm and 480 nm.
	<ol>
		<li>Put the plate on the microplate reader and click on the button edit a new protocol.</li>
		<li>Select the specific type of 96-well plate (see Table of Materials) used and the wavelength of 450 nm.</li>
		<li>Click on the button start measurement.</li>
	</ol>
	</li>
</ol>
8. Cell migration assay - two migration chambers device
<ol>
	<li>Follow steps 1-3.1 to culture the cells. 
	NOTE: Follow the steps in this section to implement the co-culture system in order to investigate the effect of the KORS secretome on HDMEC proliferation.
	<ol>
		<li>Seed the KORS at 1 x 105 cells/mL in MSCM supplemented with 5% FBS and growth factors in one of the big compartments.</li>
		<li>Place the cell culture plate at 37 &#730;C with 5% CO2 for 24 h.</li>
		<li>Put the two migration chambers device into the other large compartment of inserts.</li>
		<li>Seed the HDMECs in ECM supplemented with 5% FBS and growth factors at 7 x 105 cells/well of the two migration chambers device.</li>
		<li>Place the cell culture plate at 37 &#176;C with 5% CO2 for 24 h.</li>
		<li>Discard the media and the two migration chambers device after 24 h or at an optimal time according to the cell type that is migrating. Implement the co-culture system by the addition of 3 mL of non-supplemented basal ECM. 
		NOTE: Proceed carefully to not detach the cells. If the cells are really sensitive to detachment induced by the addition of common medium, pull off the two migration chambers device after the addition of the common medium.</li>
	</ol>
	</li>
	<li>Observe and take a picture of the surface covered by the cells at different time points under a phase-contrast microscope at 10x magnification. 
	NOTE: The pictures are taken with a phase-contrast microscope (see Table of Materials). The pictures are saved in a USB key and then analyzed by the wound healing tool plugin of the software (see Table of Materials).</li>
	<li>Measure the uncovered surface using classical quantitative analysis software.
	<ol>
		<li>Open the image on the software and activate the wound healing tool available in the macro list.</li>
		<li>Click on the m button to measure the uncovered surface of the migration image.</li>
		<li>The uncovered surface is calculated according to the following formula: 
		Percentage of coverage = ([mean area without cells at T0 &#8722; area without cells at time T]/mean area without cells at T0) &#215; 100. 
		NOTE: The 3D-printed inserts are totally adapted to most of the techniques of cell biology (such as the pseudotube formation assay, 3D cultures) and for biochemistry experiments (such as the extraction of DNA, RNA, protein).</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Regier, M. C., Alarid, E. T., Beebe, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progress+towards+understanding+heterotypic+interactions+in+multi-culture+models+of+breast+cancer.">Progress towards understanding heterotypic interactions in multi-culture models of breast cancer.</a> Integrative Biology. 8 (6), 684-692 (2016).</li><li>Do&#287;an, A., Demirci, S., Apdik, H., Apdik, E. A., &#350;ahin, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesenchymal+stem+cell+isolation+from+pulp+tissue+and+co-culture+with+cancer+cells+to+study+their+interactions.">Mesenchymal stem cell isolation from pulp tissue and co-culture with cancer cells to study their interactions.</a> Journal of Visualized Experiments. (143), e58825 (2019).</li><li>Lin, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long+non-coding+RNA+UBE2CP3+enhances+HCC+cell+secretion+of+VEGFA+and+promotes+angiogenesis+by+activating+ERK1/2/HIF-1&#945;/VEGFA+signalling+in+hepatocellular+carcinoma.">Long non-coding RNA UBE2CP3 enhances HCC cell secretion of VEGFA and promotes angiogenesis by activating ERK1/2/HIF-1&#945;/VEGFA signalling in hepatocellular carcinoma.</a> Journal of Experimental &amp; Clinical Cancer Research. 37 (1), 113 (2018).</li><li>Soares, N. 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S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tropoelastin+promotes+the+formation+of+dense,+interconnected+endothelial+networks.">Tropoelastin promotes the formation of dense, interconnected endothelial networks.</a> Biomolecules. 11 (9), 1318 (2021).</li><li>Mercatali, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+human+preclinical+model+of+osteoclastogenesis+from+peripheral+blood+monocytes+co-cultured+with+breast+cancer+cell+lines.">Development of a human preclinical model of osteoclastogenesis from peripheral blood monocytes co-cultured with breast cancer cell lines.</a> Journal of Visualized Experiments. (127), e56311 (2017).</li><li>Orona, N. S., Astort, F., Maglione, G. A., Yakisich, J. S., Tasat, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+and+indirect+effect+of+air+particles+exposure+induce+Nrf2-dependent+cardiomyocyte+cellular+response+in+vitro.">Direct and indirect effect of air particles exposure induce Nrf2-dependent cardiomyocyte cellular response in vitro.</a> Cardiovascular Toxicology. 19 (6), 575-587 (2019).</li><li>Colin-Pierre, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+glypican-1/HGF/C-met+and+glypican-1/VEGF/VEGFR2+ternary+complexes+regulate+hair+follicle+angiogenesis.">The glypican-1/HGF/C-met and glypican-1/VEGF/VEGFR2 ternary complexes regulate hair follicle angiogenesis.</a> Frontiers in Cell and Developmental Biology. 9, 781172 (2021).</li><li>Toubal, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+NC1+domain+of+type+XIX+collagen+inhibits+melanoma+cell+migration.">The NC1 domain of type XIX collagen inhibits melanoma cell migration.</a> European Journal of Dermatology. 20 (6), 712-718 (2010).</li><li>Wu, A. -. 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B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmin+releases+the+anti-tumor+peptide+from+the+NC1+domain+of+collagen+XIX.">Plasmin releases the anti-tumor peptide from the NC1 domain of collagen XIX.</a> Oncotarget. 6 (6), 3656-3668 (2015).</li><li>Martinotti, S., Ranzato, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scratch+wound+healing+assay.">Scratch wound healing assay.</a> Methods in Molecular Biology. 2109, 225-229 (2020).</li><li>Cattin, S., Ramont, L., R&#252;egg, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+and+in+vivo+validation+of+a+three-dimensional+multi-cellular+culture+model+to+study+heterotypic+interactions+in+colorectal+cancer+cell+growth,+invasion+and+metastasis.">Characterization and in vivo validation of a three-dimensional multi-cellular culture model to study heterotypic interactions in colorectal cancer cell growth, invasion and metastasis.</a> Frontiers in Bioengineering and Biotechnology. 6, 97 (2018).</li><li>Ma, Y. 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The authors declare no competing financial interests.

Indirect cell communication is commonly investigated using conditioned media or co-culture system devices. Conditioned media preparation is time-consuming upstream in the experiments, and this method is restricted to one-sided effect analyses. The previous study by Colin-Pierre et al.8 using conditioned media was conducted on the indirect cell communication between two cell types (HDMECs and KORS). The data of this previous study demonstrated the effect of KORS conditioned media on HDMEC ...

In vivo, cells communicate with each other either directly (cell contact) or indirectly (by secretion of molecules). To study cell communication, different co-culture models can be developed, such as direct co-culture (the different cell types are in direct interaction in the same well) and compartmentalized co-culture (the different cell types are in indirect interaction in different compartments of a culture system)1. Moreover, conditioned media can be used for co-culture systems, where the indirect interaction is enabled by secreted molecules contained in the conditioned media of an effector cell type being transferred to a responder cell type1.
In the case of paracrine cell communication studies, indirect co-culture systems provide models that strongly reflect cell interactions in vivo. Indirect co-culture systems have been developed and commercialized, allowing the establishment of indirect co-culture models2,3. Unfortunately, most indirect co-culture systems provide only two compartments. Other indirect co-culture systems provide multiple compartments, but they are less scalable as compared to the system reported in the present manuscript. Some of them do not allow a classical visualization under a microscope, and they often present specific application methods. In several studies, the paracrine communication between different cell types is probed by the conditioned media model4,5,6,7. This is an easier way of investigation compared to indirect co-culture systems because it does not necessitate specific methods or materials to be established1. On the other hand, the preparation of conditioned media is time-consuming and provides information only on one-way cell signaling (effector to responder)1.
In this paper, a new, simple way of investigating cell communication is proposed. Allowing the combination of several cell types in direct or indirect interaction and in 2D or 3D formats, the printed inserts present numerous advantages for setting up co-culture models easily. Adapted to be placed into the wells of 6-well plates, the 3D-printed insert is circular and allows separation of the well into four compartments (two large compartments and two small compartments; Figure 1A). The 3D-printed inserts are characterized by the absence of a bottom. Thus, the cells are in direct contact with the plate on which the insert is placed. In addition, each compartment can be coated independently of the others. Moreover, the cell behavior can be easily followed under optical microscopes. The presence of communication windows in each wall of the insert allows the addition, at the optimal time, of a common medium to perform different experiments of co-culture. Numerous combinations of co-culture can be performed to study direct and/or indirect communication between several cell types. For example, a model of indirect co-culture between four different cell types in monolayer and/or in 3D (spheroids) can be designed. A combination of direct and indirect co-culture models can also be performed by mixing different cell types in the same compartment. The effect of complex structures (organoids, tissue explant, etc.) on different cell types could be another example of models that can be made. Moreover, the 3D-printed inserts are compatible with cell biology functional assays (proliferation, migration, pseudotube formation, differentiation, etc.) and with biochemistry tests (the extraction of DNA, RNA, protein, lipids, etc.). Finally, the 3D-printed inserts provide a wide range of experimental schemes of co-culture models with the possibility to combine simultaneously different assays in the same experiment in the different compartments.
Some capacities of the 3D-printed inserts are presented to validate them as a rapid and easy-to-use co-culture model. In comparison to a previously published study conducted on paracrine cell communication, the ability of the 3D-printed inserts to be a valuable co-culture model is demonstrated. To assess this point, the regulation of endothelial cell proliferation and migration by keratinocytes was compared between the 3D-printed insert system and the classical system using conditioned media. The 3D-printed inserts allow for obtaining similar results rapidly as compared to the conventional system using conditioned media. Indeed, the 3D-printed inserts provide a robust model to study cell interactions in both directions without the necessity to produce conditioned media and with the possibility to perform in parallel the proliferation and migration assays in the same experiment.
To conclude, in this paper, a new and ready-to-use model to study cell communication is proposed. Compatible with all adherent cell types, the 3D-printed inserts allow for performing numerous combinations of co-culture that aim at being closer to in vivo conditions.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Autoclave</td>
			<td>Getinge</td>
			<td>APHP</td>
			<td>Solid cycle, 121 &#176;C for 20 min</td>
		</tr>
		<tr>
			<td>Biomed Clear</td>
			<td>Formlabs</td>
			<td>RS-F2-BMCL-01</td>
			<td>Impression performed by 3D-Morphoz company (Reims, France)</td>
		</tr>
		<tr>
			<td>Cell culture detergents&#160;</td>
			<td>Tounett</td>
			<td>A18590/0116</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell Proliferation Reagent WST-1</td>
			<td>Roche</td>
			<td>11,64,48,07,001</td>
			<td></td>
		</tr>
		<tr>
			<td>Counting slide</td>
			<td>NanoEnTek</td>
			<td>EVE-050</td>
			<td></td>
		</tr>
		<tr>
			<td>Culture-Insert 2 Well in &#956;-Dish 35 mm</td>
			<td>Ibidi</td>
			<td>80206</td>
			<td>two-migration chambers device.&#160;</td>
		</tr>
		<tr>
			<td>Endothelial cell medium</td>
			<td>ScienCell</td>
			<td>1001</td>
			<td>Basal medium +/- 25 mL of fetal bovine serum (FBS, 0025), 5 mL of endothelial cell growth supplement (ECGS, 1052), and 5 mL of penicillin/streptomycin solution (P/S, 0503).</td>
		</tr>
		<tr>
			<td>EVE Automated cell counter&#160;</td>
			<td>NanoEnTek</td>
			<td>NESCT-EVE-001E&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>EVOS XL Core</td>
			<td>Fisher Scientific</td>
			<td>AMEX1200</td>
			<td>10x of magnification</td>
		</tr>
		<tr>
			<td>Food silicon reagent and catalyst kit</td>
			<td>Artificina</td>
			<td>RTV 3428 A and B&#160;</td>
			<td>(10:1)</td>
		</tr>
		<tr>
			<td>FORM 3B printer</td>
			<td>Formlabs</td>
			<td>PKG-F3B-WSVC-DSP-BASIC</td>
			<td>Impression performed by 3D-Morphoz company</td>
		</tr>
		<tr>
			<td>Human Dermal Microvascular Endothelial Cells (HDMEC)</td>
			<td>ScienCell</td>
			<td>2000</td>
			<td></td>
		</tr>
		<tr>
			<td>Keratinocytes of Outer Root Sheath (KORS )</td>
			<td>ScienCell</td>
			<td>2420</td>
			<td></td>
		</tr>
		<tr>
			<td>Macro Wound Healing Tool Software</td>
			<td>ImageJ</td>
			<td></td>
			<td>Software used for the measurement of the uncovered surface (for migration assays)</td>
		</tr>
		<tr>
			<td>Mesenchymal stem cell medium&#160;</td>
			<td>ScienCell</td>
			<td>7501</td>
			<td>Basal medium +/-25 mL of fetal bovine serum (FBS, 0025), 5 mL of mesenchymal stem cell growth supplement (MSCGS, 7552), and 5 mL of penicillin/streptomycin solution (P/S, 0503)</td>
		</tr>
		<tr>
			<td>Microplate reader SPECTRO star NANO</td>
			<td>BMG Labtech</td>
			<td></td>
			<td>BMG LABTECH software</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Promocell</td>
			<td>C-40232</td>
			<td>Without Ca2+ / Mg2+</td>
		</tr>
		<tr>
			<td>Trypan Blue Stain</td>
			<td>NanoEnTek</td>
			<td>EBT-001</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin / EDTA</td>
			<td>Promocell</td>
			<td>C-41020</td>
			<td>Incubation of KORS at 37 &#176;C with 5% CO2 for 5 min. Incubation of HDMECs for 5 min at room temperature</td>
		</tr>
		<tr>
			<td>96-well plate Nunclon Delta Surface</td>
			<td>Thermoscientific</td>
			<td>167008</td>
			<td></td>
		</tr>
	</tbody>
</table>

an innovative 3d-printed insert designed to enable straightforward 2d and 3d cell cultures

The classical analyses of indirect communication between different cell types necessitate the use of conditioned media. Moreover, the production of conditioned media remains time-consuming and far from physiological and pathological conditions. Although a few models of co-culture are commercially available, they remain restricted to specific assays and are mostly for two types of cells. 
Here, 3D-printed inserts are used that are compatible with numerous functional assays. The insert allows the separation of one well of a 6-well plate into four compartments. A wide range of combinations can be set. Moreover, windows are designed in each wall of the compartments so that potential intercellular communication between every compartment is possible in the culture medium in a volume-dependent manner. For example, paracrine intercellular communication can be studied between four cell types in monolayer, in 3D (spheroids), or by combining both. In addition, a mix of different cell types can be seeded in the same compartment in 2D or 3D (organoids) format. The absence of a bottom in the 3D-printed inserts allows the usual culture conditions on the plate, possible coating on the plate containing the insert, and direct visualization by optical microscopy. The multiple compartments provide the possibility to collect different cell types independently or to use, in each compartment, different reagents for RNA or protein extraction. In this study, a detailed methodology is provided to use the new 3D-printed insert as a co-culture system. To demonstrate several capacities of this flexible and simple model, previously published functional assays of cell communication were performed in the new 3D-printed inserts and were demonstrated to be reproducible. The 3D-printed inserts and the conventional cell culture using conditioned media led to similar results. In conclusion, the 3D-printed insert is a simple device that can be adapted to numerous models of co-cultures with adherent cell types.

In the present work, an optimized co-culture system was described to obtain robust, reliable, and significant data comparable to classical methods through the use of conditioned media. The 3D-printed inserts mimic the in vivo microenvironment conditions of different cell types in interaction by overcoming the difficulties and the time-consuming production of conditioned media upstream in the experiments. A previously published study has been reconducted to analyze the indirect interactions between two cell types...

Watch this Scientific Journal Video about An Innovative 3D-Printed Insert Designed to Enable Straightforward 2D and 3D Cell Cultures at JoVE.com

An Innovative 3D-Printed Insert Designed to Enable Straightforward 2D and 3D Cell Cultures

In this paper, a newly designed 3D-printed insert is presented as a model of co-culture and validated through the study of the paracrine intercellular communication between endothelial cells and keratinocytes.

The classical analyses of indirect communication between different cell types necessitate the use of conditioned media. Moreover, the production of ...

an-innovative-3d-printed-insert-designed-to-enable-straightforward-2d

Universidad de Cartagena UDEC

Research

JoVE Journal

Biology

1.3K Views.  Université de Reims Champagne-Ardenne. In this paper, a newly designed 3D-printed insert is presented as a model of co-culture and validated through the study of the paracrine intercellular communication between endothelial cells and keratinocytes.

Video: An Innovative 3D-Printed Insert Designed to Enable Straightforward 2D and 3D Cell Cultures

ES Cell-derived Neuroepithelial Cell Cultures

ES cells have the potential to differentiate into cells from all germ layers, which makes them an attractive tool for the development of new therapies. In general, the differentiation of ES cells follows the concept to first generate immature progenitor cells, which then can be propagated and differentiated into mature cellular phenotypes. This also applies for ES cell-derived neurogenesis, in which the development of neural cells follows two major steps: First, the derivation and expansion of immature neuroepithelial precursors and second, their differentiation into mature neural cells. A common method to produce neural progenitors from ES cells is based on embryoid body (EB) formation, which reveals the differentiation of cells from all germ layers including neuroectoderm. An alternative and more efficient method to induce neuroepithelial cell development uses stromal cell-derived inducing activity (SDIA), which can be achieved by co-culturing ES cells with skull bone marrow-derived stromal cells (1). Both, EB formation and SDIA, reveal the development of rosette-like structures, which are thought to resemble neural tube- and/or neural crest-like progenitors. The neural precursors can be isolated, expanded and further differentiated into specific neurons and glia cells using defined culture conditions. Here, we describe the generation and isolation of such rosettes in co-culture experiments with the stromal cell line MS5 (2-5).

Derivation of neuroepithelial precursors from embryonic stem (ES) cells using stromal cell-derived inducing activity (SDIA).

ES cells have the potential to differentiate into cells from all germ layers, which makes them an attractive tool for the development of new therapies. In ...

Preparation of Neuronal Cultures from Midgastrula Stage Drosophila Embryos

This video illustrates the procedure for making primary neuronal cultures from midgastrula stage Drosophila embryos. The methods for collecting embryos and their dechorionation using bleach are demonstrated. Using a glass pipet attached to a mouth suction tube, we illustrate the removal of all cells from single embryos. The method for dispersing cells from each embyro into a small (5 l) drop of medium on an uncoated glass coverslip is demonstrated. A view through the microscope at 1 hour after plating illustrates the preferred cell density. Most of the cells that survive when grown in defined medium are neuroblasts that divide one or more times in culture before extending neuritic processes by 12-24 hours. A view through the microscope illustrates the level of neurite outgrowth and branching expected in a healthy culture at 2 days in vitro. The cultures are grown in a simple bicarbonate based defined medium, in a 5% CO2 incubator at 22-24&deg;C. Neuritic processes continue to elaborate over the first week in culture and when they make contact with neurites from neighboring cells they often form functional synaptic connections. Neurons in these cultures express voltage-gated sodium, calcium, and potassium channels and are electrically excitable. This culture system is useful for studying molecular genetic and environmental factors that regulate neuronal differentiation, excitability, and synapse formation/function.

This video demonstrates the preparation of primary neuronal cultures from midgastrula stage Drosophila embryos. Views of live cultures show cells 1 hour after plating and differentiated neurons after 2 days of growth in a bicarbonate-based defined medium. The neurons are electrically excitable and form synaptic connections.

This video illustrates the procedure for making primary neuronal cultures from midgastrula stage Drosophila embryos. The methods for collecting embryos ...

Mouse Epidermal Neural Crest Stem Cell (EPI-NCSC) Cultures

EPI-NCSC are remnants of the embryonic neural crest in an adult location, the bulge of hair follicles. They are multipotent stem cells that have the physiological property to generate a wide array of differentiated cell types, including neurons, nerve supporting cells, smooth muscle cells, bone/cartilage cells and melanocytes. EPI-NCSC are easily accessible in the hairy skin and can be isolated as a highly pure population of stem cells. This video provides a detailed protocol for preparing mouse EPI-NCSC cultures from whisker follicles. The whisker pad of an adult mouse is removed, and whisker follicles dissected. The follicles are then cut longitudinally and subsequently transversely above and below the bulge region. The bulge is removed from the collagen capsule and placed in a culture plate. EPI-NCSC start to emigrate from the bulge explants 3 to 4 days later.

Mouse Epidermal Neural Crest Stem Cell EPI-NCSC Cultures

Here we show our method to isolate mouse epidermal neural crest stem cells (EPI-NCSC). Technique involves micro-dissecting whisker follicles, isolating the bulge and placeing it into tissue culture. EPI-NCSC start to emigrate from bulge explants onto the substratum within 3 - 4 days.

EPI-NCSC are remnants of the embryonic neural crest in an adult location, the bulge of hair follicles. They are multipotent stem cells that have the ...

Preparation of Aplysia Sensory-motor Neuronal Cell Cultures

The nervous system of the marine mollusk Aplysia californica is relatively simple, consisting of approximately 20,000 neurons. The neurons are large (up to 1 mm in diameter) and identifiable, with distinct sizes, shapes, positions and pigmentations, and the cell bodies are externally exposed in five paired ganglia distributed throughout the body of the animal. These properties have allowed investigators to delineate the circuitry underlying specific behaviors in the animal1. The monosynaptic connection between sensory and motor neurons is a central component of the gill-withdrawal reflex in the animal, a simple defensive reflex in which the animal withdraws its gill in response to tactile stimulation of the siphon. This reflex undergoes forms of non-associative and associative learning, including sensitization, habituation and classical conditioning. Of particular benefit to the study of synaptic plasticity, the sensory-motor synapse can be reconstituted in culture, where well-characterized stimuli elicit forms of plasticity that have direct correlates in the behavior of the animal2,3. Specifically, application of serotonin produces a synaptic strengthening that, depending on the application protocol, lasts for minutes (short-term facilitation), hours (intermediate-term facilitation) or days (long-term facilitation). In contrast, application of the peptide transmitter FMRFamide produces a synaptic weakening or depression that, depending on the application protocol, can last from minutes to days (long-term depression). The large size of the neurons allows for repeated sharp electrode recording of synaptic strength over periods of days together with microinjection of expression vectors, siRNAs and other compounds to target specific signaling cascades and molecules and thereby identify the molecular and cell biological steps that underlie the changes in synaptic efficacy.
An additional advantage of the Aplysia culture system comes from the fact that the neurons demonstrate synapse-specificity in culture4,5. Thus, sensory neurons do not form synapses with themselves (autapses) or with other sensory neurons, nor do they form synapses with non-target identified motor neurons in culture. The varicosities, sites of synaptic contact between sensory and motor neurons, are large enough (2-7 microns in diameter) to allow synapse formation (as well as changes in synaptic morphology) with target motor neurons to be studied at the light microscopic level.
In this video, we demonstrate each step of preparing sensory-motor neuron cultures, including anesthetizing adult and juvenile Aplysia, dissecting their ganglia, protease digestion of the ganglia, removal of the connective tissue by microdissection, identification of both sensory and motor neurons and removal of each cell type by microdissection, plating of the motor neuron, addition of the sensory neuron and manipulation of the sensory neurite to form contact with the cultured motor neuron.

Preparation of Aplysia Sensory-motor Neuronal Cell Cultures

Primary cultures of Aplysia sensory-motor neurons provide a model preparation for studying synapse formation and synaptic plasticity in vitro. This video demonstrates the identification and microdissection of sensory and motor neurons from Aplysia ganglia as well as the methods for establishing and maintaining sensory-motor neurons in culture.

The nervous system of the marine mollusk Aplysia californica is relatively simple, consisting of approximately 20,000 neurons.  The neurons are large (up ...

Large Insert Environmental Genomic Library Production

The vast majority of microbes in nature currently remain inaccessible to traditional cultivation methods. Over the past decade, culture-independent environmental genomic (i.e. metagenomic) approaches have emerged, enabling researchers to bridge this cultivation gap by capturing the genetic content of indigenous microbial communities directly from the environment. To this end, genomic DNA libraries are constructed using standard albeit artful laboratory cloning techniques. Here we describe the construction of a large insert environmental genomic fosmid library with DNA derived from the vertical depth continuum of a seasonally hypoxic fjord. This protocol is directly linked to a series of connected protocols including coastal marine water sampling [1], large volume filtration of microbial biomass [2] and a DNA extraction and purification protocol [3]. At the outset, high quality genomic DNA is end-repaired with the creation of 5 -phosphorylated blunt ends. End-repaired DNA is subjected to pulsed-field gel electrophoresis (PFGE) for size selection and gel extraction is performed to recover DNA fragments between 30 and 60 thousand base pairs (Kb) in length. Size selected DNA is purified away from the PFGE gel matrix and ligated to the phosphatase-treated blunt-end fosmid CopyControl vector pCC1 (EPICENTRE <a href="http://www.epibio.com/item.asp?ID=385">http://www.epibio.com/item.asp?ID=385</a>). Linear concatemers of pCC1 and insert DNA are subsequently headfull packaged into phage particles by lambda terminase, with subsequent infection of phage-resistant E. coli cells. Successfully transduced clones are recovered on LB agar plates under antibiotic selection and archived in 384-well plate format using an automated colony picking robot (Qpix2, GENETIX). The current protocol draws from various sources including the CopyControl Fosmid Library Production Kit from EPICENTRE and the published works of multiple research groups [4-7]. Each step is presented with best practice in mind. Whenever possible we highlight subtleties in execution to improve overall quality and efficiency of library production. The whole process of fosmid library production and automated colony picking takes at least 7-10 days as there are many incubation steps included. However, there are several stopping points possible which are mentioned within the protocol.

Construction of a fosmid library with environmental genomic DNA isolated from the vertical depth continuum of a seasonally hypoxic fjord is described. The resulting clone library is picked into 384-well plates and archived for downstream sequencing and functional screening by the application of an automated colony picking system.

The vast majority of microbes in nature currently remain inaccessible to traditional cultivation methods. Over the past decade, culture-independent ...

Fabrication and Operation of an Oxygen Insert for Adherent Cellular Cultures 

Oxygen is a key modulator of many cellular pathways, but current devices permitting in vitro oxygen modulation fail to meet the needs of biomedical research. The hypoxic chamber offers a simple system to control oxygenation in standard culture vessels, but lacks precise temporal and spatial control over the oxygen concentration at the cell surface, preventing its application in studying a variety of physiological phenomena. Other systems have improved upon the hypoxic chamber, but require specialized knowledge and equipment for their operation, making them intimidating for the average researcher. A microfabricated insert for multiwell plates has been developed to more effectively control the temporal and spatial oxygen concentration to better model physiological phenomena found in vivo. The platform consists of a polydimethylsiloxane insert that nests into a standard multiwell plate and serves as a passive microfluidic gas network with a gas-permeable membrane aimed to modulate oxygen delivery to adherent cells. The device is simple to use and is connected to gas cylinders that provide the pressure to introduce the desired oxygen concentration into the platform. Fabrication involves a combination of standard SU-8 photolithography, replica molding, and defined PDMS spinning on a silicon wafer. The components of the device are bonded after surface treatment using a hand-held plasma system. Validation is accomplished with a planar fluorescent oxygen sensor. Equilibration time is on the order of minutes and a wide variety of oxygen profiles can be attained based on the device design, such as the cyclic profile achieved in this study, and even oxygen gradients to mimic those found in vivo. The device can be sterilized for cell culture using common methods without loss of function. The device's applicability to studying the in vitro wound healing response will be demonstrated.

Fabrication and Operation of an Oxygen Insert for Adherent Cellular Cultures

Fabrication and validation of an add-on platform that offers enhanced control over the spatial and temporal oxygenation in a 6-well plate. The device is adaptable to a number of culture systems and can be used to investigate the effects of oxygen on wound healing.

Oxygen is a key modulator of many cellular pathways, but current devices permitting in vitro oxygen modulation fail to meet the needs of biomedical ...

Using an Automated 3D-tracking System to Record Individual and Shoals of Adult Zebrafish

Like many aquatic animals, zebrafish (Danio rerio) moves in a 3D space. It is thus preferable to use a 3D recording system to study its behavior. The presented automatic video tracking system accomplishes this by using a mirror system and a calibration procedure that corrects for the considerable error introduced by the transition of light from water to air. With this system it is possible to record both single and groups of adult zebrafish. Before use, the system has to be calibrated. The system consists of three modules: Recording, Path Reconstruction, and Data Processing. The step-by-step protocols for calibration and using the three modules are presented. Depending on the experimental setup, the system can be used for testing neophobia, white aversion, social cohesion, motor impairments, novel object exploration etc. It is especially promising as a first-step tool to study the effects of drugs or mutations on basic behavioral patterns. The system provides information about vertical and horizontal distribution of the zebrafish, about the xyz-components of kinematic parameters (such as locomotion, velocity, acceleration, and turning angle) and it provides the data necessary to calculate parameters for social cohesions when testing shoals.

The use of a 3D automatic video system that can track individual and groups of zebrafish is described. As application example we explore the effects of the NMDA-receptor antagonist MK-801 on shoals of zebrafish.

Like many aquatic animals, zebrafish (Danio rerio) moves in a 3D space. It is thus preferable to use a 3D recording system to study its behavior. The ...

An Innovative Method for Exosome Quantification and Size Measurement

Although the biological importance of exosomes has recently gained an increasing amount of scientific and clinical attention, much is still unknown about their complex pathways, their bioavailability and their diverse functions in health and disease. Current work focuses on the presence and the behavior of exosomes (in vitro as well as in vivo) in the context of different human disorders, especially in the fields of oncology, gynecology and cardiology.
Unfortunately, neither a consensus regarding a gold standard for exosome isolation exists, nor is there an agreement on such a method for their quantitative analysis. As there are many methods for the purification of exosomes and also many possibilities for their quantitative and qualitative analysis, it is difficult to determine a combination of methods for the ideal approach. 
Here, we demonstrate nanoparticle tracking analysis (NTA), a semi-automated method for the characterization of exosomes after isolation from human plasma by ultracentrifugation. The presented results show that this approach for isolation, as well as the determination of the average number and size of exosomes, delivers reproducible and valid data, as confirmed by other methods, such as scanning electron microscopy (SEM).

A method for isolation of exosomes from whole blood and further analysis by nanoparticle tracking using a semi-automatic instrument is presented in this article. The presented technology provides an extremely sensitive method for visualizing and analyzing particles in liquid suspension.

Although the biological importance of exosomes has recently gained an increasing amount of scientific and clinical attention, much is still unknown about ...

Development of an Insert Co-culture System of Two Cellular Types in the Absence of Cell-Cell Contact

The role of secreted soluble factors in the modification of cellular responses is a recurrent theme in the study of all tissues and systems. In an attempt to make straightforward the very complex relationships between the several cellular subtypes that compose multicellular organisms, in vitro techniques have been developed to help researchers acquire a detailed understanding of single cell populations. One of these techniques uses inserts with a permeable membrane allowing secreted soluble factors to diffuse. Thus, a population of cells grown in inserts can be co-cultured in a well or dish containing a different cell type for evaluating cellular changes following paracrine signaling in the absence of cell-cell contact. Such insert co-culture systems offer various advantages over other co-culture techniques, namely bidirectional signaling, conserved cell polarity and population-specific detection of cellular changes. In addition to being utilized in the field of inflammation, cancer, angiogenesis and differentiation, these co-culture systems are of prime importance in the study of the intricate relationships that exist between the different cellular subtypes present in the central nervous system, particularly in the context of neuroinflammation. This article offers general methodological guidelines in order to set up an experiment in order to evaluating cellular changes mediated by secreted soluble factors using an insert co-culture system. Moreover, a specific protocol to measure the neuroinflammatory effects of cytokines secreted by lipopolysaccharide-activated N9 microglia on neuronal PC12 cells will be detailed, offering a concrete understanding of insert co-culture methodology.

In multicellular organisms, secreted soluble factors elicit responses from different cell types as a result of paracrine signaling. Insert co-culture systems offer a simple way to assess the changes mediated by secreted soluble factors in the absence of cell-cell contact.

The role of secreted soluble factors in the modification of cellular responses is a recurrent theme in the study of all tissues and systems. In an attempt ...

An Efficient and Flexible Cell Aggregation Method for 3D Spheroid Production

Monolayer cell culture does not adequately model the in vivo behavior of tissues, which involves complex cell-cell and cell-matrix interactions. Three-dimensional (3D) cell culture techniques are a recent innovation developed to address the shortcomings of adherent cell culture. While several techniques for generating tissue analogues in vitro have been developed, these methods are frequently complex, expensive to establish, require specialized equipment, and are generally limited by compatibility with only certain cell types. Here, we describe a rapid and flexible protocol for aggregating cells into multicellular 3D spheroids of consistent size that is compatible with growth of a variety of tumor and normal cell lines. We utilize varying concentrations of serum and methyl cellulose (MC) to promote anchorage-independent spheroid generation and prevent the formation of cell monolayers in a highly reproducible manner. Optimal conditions for individual cell lines can be achieved by adjusting MC or serum concentrations in the spheroid formation medium. The 3D spheroids generated can be collected for use in a wide range of applications, including cell signaling or gene expression studies, candidate drug screening, or in the study of cellular processes such as tumor cell invasion and migration. The protocol is also readily adapted to generate clonal spheroids from single cells, and can be adapted to assess anchorage-independent growth and anoikis-resistance. Overall, our protocol provides an easily modifiable method for generating and utilizing 3D cell spheroids in order to recapitulate the 3D microenvironment of tissues and model the in vivo growth of normal and tumor cells.

Here, we describe a rapid and flexible protocol for the formation of 3D cell spheroids through cell aggregation. This is easily adapted to multiple cell types and is suitable for use in a variety of applications including cell migration, invasion, or anoikis assays, and for imaging and quantifying cell-matrix interactions.

An Innovative 3D-Printed Insert Designed to Enable Straightforward 2D and 3D Cell Cultures

Summary

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Chapters in this video

ES Cell-derived Neuroepithelial Cell Cultures

Preparation of Neuronal Cultures from Midgastrula Stage Drosophila Embryos

Mouse Epidermal Neural Crest Stem Cell (EPI-NCSC) Cultures

Preparation of Aplysia Sensory-motor Neuronal Cell Cultures

Large Insert Environmental Genomic Library Production

Fabrication and Operation of an Oxygen Insert for Adherent Cellular Cultures

Using an Automated 3D-tracking System to Record Individual and Shoals of Adult Zebrafish

An Innovative Method for Exosome Quantification and Size Measurement

Development of an Insert Co-culture System of Two Cellular Types in the Absence of Cell-Cell Contact

An Efficient and Flexible Cell Aggregation Method for 3D Spheroid Production