Name: measuring the confluence of ipscs using an automated imaging system
Uploaded: 2020-06-10T13:30:00
Description: Watch this Scientific Journal Video about Measuring the Confluence of iPSCs Using an Automated Imaging System at JoVE.com

The study was supported by grants from the Fondazione Bambino Ges&#249; and Ricerca Corrente (Italian Ministry of Health) to C.C.&#160;&#160;We would like to thank Dr Enrico Bertini (Department of Neuroscience, Unit of Neuromuscular and Neurodegenerative Diseases, Laboratory of Molecular Medicine, Bambino Ges&#249; Children&#39;s Research Hospital), Dr Stefania Petrini (Confocal Microscopy Core Facility, Research Laboratories, Bambino Ges&#249; Children&#39;s Research Hospital), Giulia Pericoli&#160;(Department of Onco-hematology, Gene and Cell Therapy, Children&#8217;s Research Hospital Bambino Ges&#249;) and Roberta Ferretti (Department of Onco-hematology, Gene and Cell Therapy, Children&#8217;s Research Hospital Bambino Ges&#249;) for scientific discussions and technical help. Maria Vinci is recipient of a &#8220;Children with Cancer UK fellowship&#8221;.

1. Coating 96 well plates
NOTE: Different coatings were tested in the same plate but separate wells (see Supplemental File).
<ol>
	<li>Dilute the Matrigel 1:100 in DMEM. Add 100 &#181;L per well to the 96 well plates and incubate for 1 h at room temperature. Following this, remove the solution and wash the wells with 100 &#160;&#181;L&#160;of DMEM twice.</li>
	<li>Dilute laminin (20 &#181;g/mL, LN-521) in PBS (with calcium and magnesium). Add 100 &#181;L to the well and incu...

<ol>
	<li>Masotti, 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=Aged+iPSCs+display+an+uncommon+mitochondrial+appearance+and+fail+to+undergo+in+vitro+neurogenesis.">Aged iPSCs display an uncommon mitochondrial appearance and fail to undergo in vitro neurogenesis.</a> Aging (Albany NY). 6 (12), 1094-1108 (2014).</li><li>Xu, 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=Feeder-free+growth+of+undifferentiated+human+embryonic+stem+cells.">Feeder-free growth of undifferentiated human embryonic stem cells.</a> Nature Biotechnology. 19, 971-974 (2001).</li><li>Kleinman, H. K., 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=Isolation+and+characterization+of+type+IV+procollagen,+laminin,+and+heparan+sulfate+proteoglycan+from+the+EHS+sarcoma.">Isolation and characterization of type IV procollagen, laminin, and heparan sulfate proteoglycan from the EHS sarcoma.</a> Biochemistry. 21 (24), 6188-6193 (1982).</li><li>Rodin, S., 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=Clonal+culturing+of+human+embryonic+stem+cells+on+laminin-521/E-cadherin+matrix+in+defined+and+xeno-free+environment.">Clonal culturing of human embryonic stem cells on laminin-521/E-cadherin matrix in defined and xeno-free environment.</a> Nature Communications. 5, 3195 (2014).</li><li>Rodin, S., Antonsson, L., Hovatta, O., Tryggvason, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monolayer+culturing+and+cloning+of+human+pluripotent+stem+cells+on+laminin-521+based+matrices+under+xeno-free+and+chemically+defined+conditions.">Monolayer culturing and cloning of human pluripotent stem cells on laminin-521 based matrices under xeno-free and chemically defined conditions.</a> Nature Protocols. 9 (10), 2354-2368 (2014).</li><li>Laperle, 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=&#945;-5+Laminin+Synthesized+by+Human+Pluripotent+Stem+Cells+Promotes+Self-Renewal.">&#945;-5 Laminin Synthesized by Human Pluripotent Stem Cells Promotes Self-Renewal.</a> Stem Cell Reports. 5 (2), 195-206 (2015).</li><li>Albalushi, H., 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=Laminin+521+stabilizes+the+pluripotency+expression+pattern+of+human+embryonic+stem+cells+initially+derived+on+feeder+cells.">Laminin 521 stabilizes the pluripotency expression pattern of human embryonic stem cells initially derived on feeder cells.</a> Stem Cell International. 2018, 7127042 (2018).</li><li>Zhang, D., 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=Niche-derived+laminin-511+promotes+midbrain+dopaminergic+neuron+survival+and+differentiation+through+YAP.">Niche-derived laminin-511 promotes midbrain dopaminergic neuron survival and differentiation through YAP.</a> Science Signaling. 10 (493), (2017).</li><li>Lu, H. F., 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=A+defined+xeno-free+and+feeder-free+culture+system+for+the+derivation,+expansion+and+direct+differentiation+of+transgene-free+patient-specific+induced+pluripotent+stem+cells.">A defined xeno-free and feeder-free culture system for the derivation, expansion and direct differentiation of transgene-free patient-specific induced pluripotent stem cells.</a> Biomaterials. 35 (9), 2816-2826 (2015).</li><li>Miyazaki, T., Nakatsuji, N., Suemori, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimization+of+slow+cooling+cryopreservation+for+human+pluripotent+stem+cells.">Optimization of slow cooling cryopreservation for human pluripotent stem cells.</a> Genesis. 52 (1), 49-55 (2014).</li><li>Bergstr&#246;m, R., Str&#246;m, S., Holm, F., Feki, A., Hovatta, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Xeno-free+culture+of+human+pluripotent+stem+cells.">Xeno-free culture of human pluripotent stem cells.</a> Methods in Molecular Biology. 767, 125-136 (2011).</li><li>Braam, S. R., 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=Recombinant+vitronectin+is+a+functionally+defined+substrate+that+supports+human+embryonic+stem+cell+self-renewal+via+alphavbeta5+integrin.">Recombinant vitronectin is a functionally defined substrate that supports human embryonic stem cell self-renewal via alphavbeta5 integrin.</a> Stem Cells. 26 (9), 2257-2265 (2008).</li><li>Chen, G., 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=Chemically+defined+conditions+for+human+iPSC+derivation+and+culture.">Chemically defined conditions for human iPSC derivation and culture.</a> Nature Methods. 8 (5), 424-429 (2008).</li><li>Li, 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=Impact+of+vitronectin+concentration+and+surface+properties+on+the+stable+propagation+of+human+embryonic+stem+cells.">Impact of vitronectin concentration and surface properties on the stable propagation of human embryonic stem cells.</a> Biointerphases. 5 (3), 132-142 (2010).</li><li>Prowse, A. 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=Long-term+culture+of+human+embryonic+stem+cells+on+recombinant+vitronectin+in+ascorbate+free+media.">Long-term culture of human embryonic stem cells on recombinant vitronectin in ascorbate free media.</a> Biomaterials. 31 (32), 8281-8288 (2010).</li><li>Rowland, T. 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=Roles+of+integrins+in+human+induced+pluripotent+stem+cell+growth+on+Matrigel+and+vitronectin.">Roles of integrins in human induced pluripotent stem cell growth on Matrigel and vitronectin.</a> Stem Cells and Development. 19 (8), 1231-1240 (2010).</li><li>Ruoslahti, E., Engvall, E., Hayman, E. G., Spiro, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+studies+on+amniotic+fluid+and+plasma+fibronectins.">Comparative studies on amniotic fluid and plasma fibronectins.</a> Biochemistry. 193 (1), 295-299 (1981).</li><li>Ni, H., Li, A., Simonsen, N., Wilkins, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrin+activation+by+dithiothreitol+or+Mn2++induces+a+ligand-occupied+conformation+and+exposure+of+a+novel+NH2-terminal+regulatory+site+on+the+beta1+integrin+chain.">Integrin activation by dithiothreitol or Mn2+ induces a ligand-occupied conformation and exposure of a novel NH2-terminal regulatory site on the beta1 integrin chain.</a> Biological Chemistry. 273 (14), 7981-7987 (1998).</li><li>Seltana, A., Basora, N., Beaulieu, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intestinal+epithelial+wound+healing+assay+in+an+epithelial-mesenchymal+co-culture+system.">Intestinal epithelial wound healing assay in an epithelial-mesenchymal co-culture system.</a> Wound Repair &amp; Regeneration. 18 (1), 114-122 (2010).</li><li>Amit, M., Shariki, C., Margulets, V., Itskovitz-Eldor, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Feeder+layer-and+serum-free+culture+of+human+embryonic+stem+cells.">Feeder layer-and serum-free culture of human embryonic stem cells.</a> Biology of Reproduction. 70 (3), 837-845 (2004).</li><li>Vaheri, A., Mosher, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+molecular+weight,+cell+surface-associated+glyco-protein+(fibronectin)+lost+in+malignant+transformation.">High molecular weight, cell surface-associated glyco-protein (fibronectin) lost in malignant transformation.</a> Biochimica et Biophysica Acta. 516 (1), 1-25 (1978).</li><li>Mao, Y., Schwarzbauer, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibronectin+fibrillogenesis,+a+cell-mediated+matrix+assembly+process.">Fibronectin fibrillogenesis, a cell-mediated matrix assembly process.</a> Matrix Biology. 24 (6), 389-399 (2005).</li><li>Polyak, K., Weinberg, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transitions+between+epithelial+and+mesenchymal+states:+acquisition+of+malignant+and+stem+cell+traits.">Transitions between epithelial and mesenchymal states: acquisition of malignant and stem cell traits.</a> Nature Reviews Cancer. 9 (4), 265-273 (2009).</li><li>Kadler, K. E., Hill, A., Canty-Laird, E. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collagen+fibrillogenesis:+fibronectin,+integrins,+and+minor+collagens+as+organizers+and+nucleators.">Collagen fibrillogenesis: fibronectin, integrins, and minor collagens as organizers and nucleators.</a> Current Opinion in Cell Biology. 20 (5), 495-501 (2008).</li><li>Hunt, G. C., Schwarzbauer, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tightening+the+connections+between+cadherins+and+fibronectin+matrix.">Tightening the connections between cadherins and fibronectin matrix.</a> Developmental Cell. 16 (3), 327-328 (2009).</li><li>Villa-Diaz, L. G., Ross, A. M., Lahann, J., Krebsbach, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concise+review:+The+evolution+of+human+pluripotent+stem+cell+culture:+from+feeder+cells+to+synthetic+coatings.">Concise review: The evolution of human pluripotent stem cell culture: from feeder cells to synthetic coatings.</a> Stem Cells. 31 (1), 1-7 (2013).</li><li>Engler, A. J., Sen, S., Sweeney, H. L., Discher, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Matrix+elasticity+directs+stem+cell+lineage+specification.">Matrix elasticity directs stem cell lineage specification.</a> Cell. 126 (4), 677-689 (2006).</li><li>Vigilante, 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=Identifying+Extrinsic+versus+Intrinsic+Drivers+of+Variation+in+Cell+Behavior+in+Human+iPSC+Lines+from+Healthy+Donors.">Identifying Extrinsic versus Intrinsic Drivers of Variation in Cell Behavior in Human iPSC Lines from Healthy Donors.</a> Cell Reports. 26 (8), 2078-2087 (2019).</li></ol>

The use of iPSCs for disease modeling and future drug screening together with their possible application in precision medicine makes it a technology of great relevance and for this reason we believe that it is necessary to clearly understand the in vitro culturing condition that better resemble the physiological situation of embryonic stem cells. In this context, we tested different ECM coatings using&#160;wild type iPSCs in order to understand the conditions that allow the cells to remain in a healthy and undifferentiat...

Induced pluripotent stem cells (iPSCs) are obtained from somatic cells and can be differentiated into different cell types. They are often used as a system to model disease pathogenesis or perform drug screening, and also offer the potential to be used in the context of personalized medicine. Since iPSCs have great potential, it is important to fully characterize them for use as a reliable model system. We previously showed the importance of growing iPSCs in a hypoxic environment as these cells rely on glycolysis and an aerobic environment can cause redox imbalance1. iPSCs are also vulnerable to other culture conditions, particularly the extracellular environment. Optimization of culture conditions is a key issue to keep them healthy and proliferating. A healthy iPSC culture will lead to healthy differentiated cells that generally are the endpoint of the model used to understand molecular, cellular and functional features of specific human disorders or cellular processes.
In this study, a simple protocol has been used to test the confluence of iPSCs using different coating conditions in separate wells. iPSCs require a feeder layer of murine embryonic fibroblasts (MEF) in order to properly attach, but the coexistence of iPSCs and MEF makes it difficult to perform analysis like RNA or protein extraction since two populations of cells are present. In order to avoid the feeder layer, different proteins belonging to the extracellular matrix (ECM) have been used to recreate the natural cell niche and to have feeder free iPSC culture. In particular, Matrigel is a solubilized basement membrane preparation extracted from the Engelbreth-Holm-Swarm (EHS) mouse sarcoma, which is enriched in extracellular matrix proteins (i.e., laminin, collagen IV, heparan sulfate proteoglycans, entactin/nidogen, and growth factors)2,3. The other used coating conditions are instead purified proteins with known relevance in building the ECMs: laminin-521 is known to be secreted by human pluripotent stem cells (hPSCs) in the inner cell mass of the embryo and it is one of the most common laminins in the body after birth4,5,6,7,8,9,10,11; vitronectin is a xeno-free cell culture matrix known to support growth and differentiation of hPSC12,13,14,15,16; fibronectin is an ECM protein important for vertebrate development and the attachment and maintenance of embryonic stem cells in a pluripotent state17,18,19,20,21,22,23,24,25. Since different coating conditions are available, we compare them in terms of their effect on iPSCs&#8217; confluence.

<table border="0" cellpadding="0" cellspacing="0" style="width:1124px;" width="1123">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:589px;">10 mL Stripette Serological Pipets, Polystyrene, Individually Paper/Plastic Wrapped, Sterile</td>
			<td style="width:281px;">Corning</td>
			<td style="width:77px;">4488</td>
			<td style="width:176px;">Tool</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">15 mL high-clarity polypropylene (PP) conical centrifuge tubes</td>
			<td>Falcon</td>
			<td>352097</td>
			<td>Tool</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">1x PBS (With Ca2+; Mg2+)</td>
			<td>Thermofisher</td>
			<td>14040133</td>
			<td>Medium</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">1x PBS (without Ca2+; Mg2+)</td>
			<td>Euroclone</td>
			<td>ECB4004L</td>
			<td>Medium</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">5 mL Stripette Serological Pipets, Polystyrene, Individually Paper/Plastic Wrapped, Sterile</td>
			<td>Corning</td>
			<td>4487</td>
			<td>Tool</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Cell culture microplate, 96 WELL, PS, F-Bottom</td>
			<td>Greiner Bio One</td>
			<td>655090</td>
			<td>Support</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Cell culture plate, 6 well</td>
			<td>Costar</td>
			<td>3516</td>
			<td>Support</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">DMEM (Dulbecco&#39;s Modified Eagle&#39;s Medium- high glucose)</td>
			<td>Sigma</td>
			<td>D5671</td>
			<td>Medium</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">EDTA</td>
			<td>Sigma</td>
			<td>ED4SS-500g</td>
			<td>Reagent</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Epi Episomal iPSC Reprogramming Kit</td>
			<td>Invitrogen</td>
			<td>A15960</td>
			<td>Reagent</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">FAST - READ 102</td>
			<td>Biosigma</td>
			<td>BVS100</td>
			<td>Tool</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Fetal Bovine Serum (FBS)</td>
			<td>Gibco</td>
			<td>10270106</td>
			<td>Medium</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Fibronectin</td>
			<td>Merck</td>
			<td>FC010</td>
			<td>Coating</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Glycerol</td>
			<td>Sigma</td>
			<td>G5516</td>
			<td>Reagent</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">H2O</td>
			<td></td>
			<td>MILLIQ</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hoechst</td>
			<td>Thermofisher</td>
			<td>33342</td>
			<td>Reagent</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Laminin 521</td>
			<td>Stem Cell Technologies</td>
			<td>77003</td>
			<td>Coating</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">L-Glutamine (200 mM)</td>
			<td>Gibco</td>
			<td>LS25030081</td>
			<td>Reagent</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Matrigel</td>
			<td>Corning Matrigel hESC-Qualified Matrix</td>
			<td>354277</td>
			<td>Coating</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:589px;">Mouse embryonic fibroblasts (MEF)</td>
			<td>Life Technologies</td>
			<td>A24903</td>
			<td>Coating</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MTESR1 Medium</td>
			<td>Stem Cell Technologies</td>
			<td>85851</td>
			<td>Medium</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">MTESR1 Supplement</td>
			<td>Stem Cell Technologies</td>
			<td>85852</td>
			<td>Medium</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Penicillin-Streptomycin (10,000 U/mL)</td>
			<td>Gibco</td>
			<td>15140122</td>
			<td>Reagent</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Phalloidin</td>
			<td>Sigma</td>
			<td>P1951</td>
			<td>Reagent</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Vitronectin</td>
			<td>Stem Cell Technologies</td>
			<td>7180</td>
			<td>Coating</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Y-27632</td>
			<td>Sigma</td>
			<td>Y0503</td>
			<td>Reagent</td>
		</tr>
	</tbody>
</table>

measuring the confluence of ipscs using an automated imaging system

This study focuses on understanding how growing iPSCs on different ECM coating substrates can affect cell confluence. A protocol to assess iPSC confluence in real time has been established without the need to count cells in single cell suspension to avoid any growth perturbation. A high-content image analysis system was used to assess iPCS confluence on 4 different ECMs over time in an automated manner. Different analysis settings were used to assess cell confluence of adherent iPSCs and only a slight difference (at 24 and 48 hours with laminin) has been observed whether a 60, 80 or 100% mask was applied. We also show that laminin lead to the best confluence compared to Matrigel, vitronectin and fibronectin.

In this study, we investigated iPSCs confluence when grown on different coating conditions. Using a cytometer, we were able to obtain readily informative results in triplicates in 5 days. Since iPSCs hardly attach to plastic vessels and a coating is necessary to support their proliferation, we decided to monitor the confluence of human iPSCs as it is indicative of the health of the cell culture and it may reflect on their differentiation potential. After in vitro expansion, we seeded the iPSCs on different ECM substrates...

Watch this Scientific Journal Video about Measuring the Confluence of iPSCs Using an Automated Imaging System at JoVE.com

Measuring the Confluence of iPSCs Using an Automated Imaging System

The goal of the protocol is to compare different extracellular matrix (ECM) coating conditions to assess how differential coating affects the growth rate of induced pluripotent stem cells (iPSCs). In particular, we aim to set up conditions to obtain optimal growth of iPSC cultures.

This study focuses on understanding how growing iPSCs on different ECM coating substrates can affect cell confluence. A protocol to assess iPSC confluence ...

This protocol is significant because it allows a quick assessment of induced pluripotent stem cell confluence on different extracellular matrix coating substrates in real time. The main advantage of this protocol is that it does not require the single cell suspension counting, thereby preventing growth perturbation to iPSCs, which are sensitive to passaging. Demonstrating the procedure will be Valentina Magliocca, a postdoc from my laboratory.To set up basement membrane matrix-coated plates, dilute basement membrane matrix, set a 1 to 100 ratio in DMEM, and add 100 microliters of the resulting solution to each well of a 96-well plate. When all of the wells have been coded, place the plate into the cell culture incubator for one hour. At the end of the incubation, discard the basement membrane matrix solution, and wash each well two times with 100 microliters of fresh DMEM per well.To set up laminin-coated plates, dilute 20 micrograms per milliliter of laminin in PBS with calcium and magnesium, and add 100 microliters of the laminin solution to each well of a new 96-well plate. Then incubate the plate at four degrees Celsius overnight before washing the wells two times with fresh DMEM as demonstrated. To set up Vitronectin-coated plates, dilute 10 micrograms per milliliter of Vitronectin in dilution buffer, and add 100 microliters of buffer to each well of a new 96-well plate.After one-hour incubation at room temperature, wash the wells with 100 microliters of PBS without calcium and magnesium per well. To prepare human fibronectin-coated plates, dilute 30 micrograms per milliliter of fibronectin in double-distilled water, and add 100 microliters of the fibronectin solution to each well of a new 96-well plate. After a 45-minute incubation at room temperature, wash the wells with fresh DMEM as demonstrated.Two days before setting up an iPSC culture, seed mouse embryonic fibroblasts at a 2.4 by 10 to the fourth per square centimeter density in complete cell culture medium into each of two wells of six-wells cell culture plates, and place the plates in the cell culture incubator. To set up an iPSC culture, warm a stock solution of cryopreserved iPSCs in a 37 degrees Celsius water bath. When the cells have just thawed, clean the vial with 70%ethanol, and place the cells into a biological safety cabinet.Using a 1000-microliter pipette, transfer the cells drop by drop into a sterile 15-milliliter conical tube containing five milliliters of pre-warmed cell culture medium. Collect the cells by centrifugation, and resuspend the pellet in four milliliters of fresh cell culture medium. Then plate 1 by 10 to the fifth cells into each of two wells of the mouse embryonic fibroblast-seeded six-well plates.After seeding, supplement the cell cultures with 10 micromolar of the ROCK inhibitor Y-27632, and place the plates in the cell culture incubator for four to five weeks. When the cells reach 70 to 80%confluency, treat each culture with one milliliter of 0.5 millimolar EDTA for three to five minutes at room temperature. When the cells have detached, split the cells at a one to four ratio in fresh cell culture medium, and plate the cells in each of the four remaining wells of the six-well plate under feeder-free conditions.Then return the plates to the cell culture incubator. To assess the effects of the different coatings on cell confluence after at least one month of culture under feeder-free conditions, use disposable counting slides to count the cells from each culture using a counting chamber. Dilute the cells to a one by 10 to the fourth cells per 200 microliters of medium concentration, and seed the cells in triplicate into each of three wells of one covering-coated 96-well plate per condition.When all of the cells have been plated, place the plates in the cell culture incubator for 24 hours. The next day and every day for the next five days thereafter, perform automated imaging of the cells using the auto-contrast and auto-exposure settings for optimal visualization. To evaluate the changes in focus due to the light refraction at the border of the wells, set the analysis settings to confluence analysis to apply a mask of 60, 80 or 100%per well, and use the different mask analysis settings to analyze the cell confluence at each time point.To compare the overall differences of the different coding conditions, use the sample data to perform the student's paired-sample T-test, reporting the quantitative results as the mean changes in confluence, plus or minus the standard error of the mean. For characterization of the cytoskeletal microfilaments, first, fix the cells with 100 microliters of 4%paraformaldehyde in PBS per well for 10 minutes at room temperature, followed by two 10-minute washes in 200 microliters of PBS per wash. Transfer the previously placed cover slip from the plate to the microscope slide.Add 100 microliters of 5%bovine serum and 0.1%Triton in PBS to each well for one hour at room temperature to block any non-specific binding, and wash the samples with two 10-minute PBS washes as demonstrated. After the second wash, add 100 microliters of Phalloidin conjugate working solution per sample for a one-hour incubation at room temperature, followed by two 10-minute washes in PBS. Next, stain the nuclei with Hoechst 33342 diluted to a one-to-10, 000 concentration in PBS for 10 minutes at room temperature followed by two PBS washes.After the second wash, rinse the cells with water, and let the plates dry under a chemical hood. When the glass coverslip has dried, cover the cells with 100 microliters of an appropriate mounting medium per well, and locate the cells on a laser scanning confocal microscope equipped with a white light laser source and a 405 nanometer diode laser at the appropriate excitation and emission wavelengths. Then select the 63x oil immersion objective, and acquire sequential confocal images of the cells.Phalloidin staining allows visualization of the degree of cell adhesion to the surface of a vessel and specifically, the coating used for the vessel. Cells that are adherent to a coating demonstrate clearly visible cytoskeletal microfilaments instead of collapsed microfilaments. Brightfield imaging also allows imaging of the level of adhesion of the iPSCs to the coated surfaces.iPSCs seeded on laminin demonstrate a high rate of cell proliferation in a linear fashion over time compared to other coatings. Cells seeded on basement membrane matrix, Vitronectin and human fibronectin, in contrast, exhibit a linear proliferation rate in the first 96 hours with an increased slope in the confluence curve during the last 24 hours independently of the mask used. As the initial difference at 24 hours for the different coatings can be due to differences in cell attachment, cell growth can be normalized to the 24 hour data for the later time points.As observed, no differences exist in terms of confluence among the different coatings, suggesting that the differences observed within the laminin-coated cultures are most likely due to an increased ability of the iPSCs to adhere to this coating when passaged. This study may contribute to the development of standardized methodologies for culturing iPSCs, and may aid in their future possible use in clinics. We are currently investigating the biology of the major cell surface receptors that mediate cell-ECM contacts and that may be responsible for the maintenance of their self-renewal ability.

measuring-the-confluence-of-ipscs-using-an-automated-imaging-system

Research

JoVE Journal

Biology

Bioelectric Analyses of an Osseointegrated Intelligent Implant Design System for Amputees

The projected number of American amputees is expected to rise to 3.6 million by 2050.  Many of these individuals depend on artificial limbs to perform routine activities, but prosthetic suspensions using traditional socket technology can prove to be cumbersome and uncomfortable for a person with limb loss.  Moreover, for those with high proximal amputations, limited residual limb length may prevent exoprosthesis attachment all together. Osseointegrated implant technology is a novel operative procedure which allows firm skeletal attachment between the host bone and an implant. Preliminary results in European amputees with osseointegrated implants have shown improved clinical outcomes by allowing direct transfer of loads to the bone-implant interface.  Despite the apparent advantages of osseointegration over socket technology, the current rehabilitation procedures require long periods of restrictive load bearing prior which may be reduced with expedited skeletal attachment via electrical stimulation.  The goal of the osseointegrated intelligent implant design (OIID) system is to make the implant part of an electrical system to accelerate skeletal attachment and help prevent periprosthetic infection. To determine optimal electrode size and placement, we initiated proof of concept with computational modeling of the electric fields and current densities that arise during electrical stimulation of amputee residual limbs.  In order to provide insure patient safety, subjects with retrospective computed tomography scans were selected and three dimensional reconstructions were created using customized software programs to ensure anatomical accuracy (Seg3D and SCIRun) in an IRB and HIPAA approved study.  These software packages supported the development of patient specific models and allowed for interactive manipulation of electrode position and size. Preliminary results indicate that electric fields and current densities can be generated at the implant interface to achieve the homogenous electric field distributions   required to induce osteoblast migration, enhance skeletal fixation and may help prevent periprosthetic infections.  Based on the electrode configurations experimented with in the model, an external two band configuration will be advocated in the future.

There is a need to develop alternative prosthesis attachment due to limb loss attributed to vascular occlusive diseases and trauma. The goal of the work is to introduce an osseointegrated intelligent implant design system to increase skeletal fixation and reduce periprosthetic infection rates for patients needing osseointegrated technology.

The projected number of American amputees is expected to rise to 3.6 million by 2050.  Many of these individuals depend on artificial limbs to perform ...

Measuring the Bending Stiffness of Bacterial Cells Using an Optical Trap

We developed a protocol to measure the bending rigidity of filamentous rod-shaped bacteria. Forces are applied with an optical trap, a microscopic three-dimensional spring made of light that is formed when a high-intensity laser beam is focused to a very small spot by a microscope's objective lens. To bend a cell, we first bind live bacteria to a chemically-treated coverslip. As these cells grow, the middle of the cells remains bound to the coverslip but the growing ends are free of this restraint. By inducing filamentous growth with the drug cephalexin, we are able to identify cells in which one end of the cell was stuck to the surface while the other end remained unattached and susceptible to bending forces. A bending force is then applied with an optical trap by binding a polylysine-coated bead to the tip of a growing cell. Both the force and the displacement of the bead are recorded and the bending stiffness of the cell is the slope of this relationship.

We present a protocol for bending filamentous bacterial cells attached to a cover-slip surface with an optical trap to measure the cellular bending stiffness.

We developed a protocol to measure the bending rigidity of filamentous rod-shaped bacteria. Forces are applied with an optical trap, a microscopic ...

An Assay for Measuring the Activity of Escherichia coli Inducible Lysine Decarboxyase

Escherichia coli is an enteric bacterium that is capable of growing over a wide range of pH values (pH 5 - 9)1 and, incredibly, is able to survive extreme acid stresses including passage through the mammalian stomach where the pH can fall to as low as pH 1 - 22. To enable such a broad range of acidic pH survival, E. coli possesses four different inducible amino acid decarboxylases that decarboxylate their substrate amino acids in a proton-dependent manner thus raising the internal pH. The decarboxylases include the glutamic acid decarboxylases GadA and GadB3, the arginine decarboxylase AdiA4, the lysine decarboxylase LdcI5, 6 and the ornithine decarboxylase SpeF7. All of these enzymes utilize pyridoxal-5'-phospate as a co-factor8 and function together with inner-membrane substrate-product antiporters that remove decarboxylation products to the external medium in exchange for fresh substrate2. In the case of LdcI, the lysine-cadaverine antiporter is called CadB. Recently, we determined the X-ray crystal structure of LdcI to 2.0 &#197;, and we discovered a novel small-molecule bound to LdcI the stringent response regulator guanosine 5'-diphosphate,3'-diphosphate (ppGpp) 14. The stringent response occurs when exponentially growing cells experience nutrient deprivation or one of a number of other stresses9. As a result, cells produce ppGpp which leads to a signaling cascade culminating in the shift from exponential growth to stationary phase growth10. We have demonstrated that ppGpp is a specific inhibitor of LdcI 14. Here we describe the lysine decarboxylase assay, modified from the assay developed by Phan et al.11, that we have used to determine the activity of LdcI and the effect of pppGpp/ppGpp on that activity. The LdcI decarboxylation reaction removes the &alpha;-carboxy group of L-lysine and produces carbon dioxide and the polyamine cadaverine (1,5-diaminopentane)5. L-lysine and cadaverine can be reacted with 2,4,6-trinitrobenzensulfonic acid (TNBS) at high pH to generate N,N'-bistrinitrophenylcadaverine (TNP-cadaverine) and N,N&#8242;-bistrinitrophenyllysine (TNP-lysine), respectively11. The TNP-cadaverine can be separated from the TNP-lysine as the former is soluble in organic solvents such as toluene while the latter is not (See Figure 1). The linear range of the assay was determined empirically using purified cadaverine.

An Assay for Measuring the Activity of Escherichia coli Inducible Lysine Decarboxyase

The activity of the inducible lysine decarboxylase is monitored by reacting the substrate L-lysine and the product cadaverine with 2,4,6-trinitrobenzensulfonic acid to form adducts that have differential solubility in toluene.

Escherichia coli is an enteric bacterium that is capable of growing over a wide range of pH values (pH 5 - 9)1 and, incredibly, is able to survive extreme ...

A Simple Method for Imaging Arabidopsis Leaves Using Perfluorodecalin as an Infiltrative Imaging Medium

The problem of acquiring high-resolution images deep into biological samples is widely acknowledged1. In air-filled tissue such as the spongy mesophyll of plant leaves or vertebrate lungs further difficulties arise from multiple transitions in refractive index between cellular components, between cells and airspaces and between the biological tissue and the rest of the optical system. Moreover, refractive index mismatches lead to attenuation of fluorophore excitation and signal emission in fluorescence microscopy. We describe here the application of the perfluorocarbon, perfluorodecalin (PFD), as an infiltrative imaging medium which optically improves laser scanning confocal microscopy (LSCM) sample imaging at depth, without resorting to damaging increases in laser power and has minimal physiological impact2. We describe the protocol for use of PFD with Arabidopsis thaliana leaf tissue, which is optically complex as a result of its structure (Figure 1). PFD has a number of attributes that make it suitable for this use3. The refractive index of PFD (1.313) is comparable with that of water (1.333) and is closer to that of cytosol (approx. 1.4) than air (1.000). In addition, PFD is readily available, non-fluorescent and is non-toxic. The low surface tension of PFD (19 dynes cm-1) is lower than that of water (72 dynes cm-1) and also below the limit (25 - 30 dyne cm-1) for stomatal penetration4, which allows it to flood the spongy mesophyll airspaces without the application of a potentially destructive vacuum or surfactant. Finally and crucially, PFD has a great capacity for dissolving CO2 and O2, which allows gas exchange to be maintained in the flooded tissue, thus minimizing the physiological impact on the sample. These properties have been used in various applications which include partial liquid breathing and lung inflation5,6, surgery7, artificial blood8, oxygenation of growth media9, and studies of ice crystal formation in plants10. Currently, it is common to mount tissue in water or aqueous buffer for live confocal imaging. We consider that the use of PFD as a mounting medium represents an improvement on existing practice and allows the simple preparation of live whole leaf samples for imaging.

A Simple Method for Imaging Arabidopsis Leaves Using Perfluorodecalin as an Infiltrative Imaging Medium

We describe the use of perfluorodecalin as an infiltrative mounting medium. This is a simple method for improving depth of imaging in Arabidopsis thaliana leaf tissue with minimal physiological impact.

The problem of acquiring high-resolution images deep into biological samples is widely acknowledged1. In air-filled tissue such as the spongy mesophyll of ...

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 ...

Measuring the Effects of Bacteria on C. Elegans Behavior Using an Egg Retention Assay

C. elegans egg-laying behavior is affected by environmental cues such as osmolarity1 and vibration2. In the total absence of food C. elegans also cease egg-laying and retain fertilized eggs in their uterus3. However, the effect of different sources of food, especially pathogenic bacteria and particularly Enterococcus faecalis, on egg-laying
	behavior is not well characterized. The egg-in-worm (EIW) assay is a useful tool to quantify the effects of different types of bacteria, in this case E. faecalis, on egg- laying behavior.
	
	EIW assays involve counting the number of eggs retained in the uterus of C. elegans4. The EIW assay involves bleaching staged, gravid adult C. elegans to remove the cuticle and separate the retained eggs from the animal. Prior to bleaching, worms are exposed to bacteria (or any type of environmental cue) for a fixed period of time. After bleaching, one is very easily able to count the number of eggs retained inside the uterus of the worms. In this assay, a quantifiable increase in egg retention after E. faecalis exposure can be easily measured. The EIW assay is a behavioral assay that may be used to screen for potentially pathogenic bacteria or the presence of environmental toxins. In addition, the EIW assay may be a tool to screen for drugs that affect neurotransmitter signaling since egg-laying behavior is modulated by neurotransmitters such as serotonin and acetylcholine5-9.

Measuring the Effects of Bacteria on C. Elegans Behavior Using an Egg Retention Assay

An egg-in-worm (EIW) assay is a useful method to quantify egg-laying behavior. Alterations in egg laying can be a behavioral response of the model organism Caenorhabditis elegans to potentially harmful environmental substances such as those produced by pathogenic bacteria.

C. elegans egg-laying behavior is  affected by environmental cues such as osmolarity1 and  vibration2. In the total absence of food C. elegans also cease ...

Measuring the Osmotic Water Permeability Coefficient (Pf) of Spherical Cells: Isolated Plant Protoplasts as an Example

Studying AQP regulation mechanisms is crucial for the understanding of water relations at both the cellular and the whole plant levels. Presented here is a simple and very efficient method for the determination of the osmotic water permeability coefficient (Pf) in plant protoplasts, applicable in principle also to other spherical cells such as frog oocytes. The first step of the assay is the isolation of protoplasts from the plant tissue of interest by enzymatic digestion into a chamber with an appropriate isotonic solution. The second step consists of an osmotic challenge assay: protoplasts immobilized on the bottom of the chamber are submitted to a constant perfusion starting with an isotonic solution and followed by a hypotonic solution. The cell swelling is video recorded. In the third step, the images are processed offline to yield volume changes, and the time course of the volume changes is correlated with the time course of the change in osmolarity of the chamber perfusion medium, using a curve fitting procedure written in Matlab (the &#8216;PfFit&#8217;), to yield Pf.

Measuring the Osmotic Water Permeability Coefficient Pf of Spherical Cells: Isolated Plant Protoplasts as an Example

Measuring the osmotic water permeability coefficient (Pf) of cells can help understand the regulatory mechanisms of aquaporins (AQPs). Pf determination in spherical plant cell protoplasts presented here involves protoplasts isolation and numerical analysis of their initial rate of volume change as a result of an osmotic challenge during constant bath perfusion.

Studying AQP regulation mechanisms is crucial for the understanding of water relations at both the cellular and the whole plant levels. Presented here is ...

Imaging Spatial Reorganization of a MAPK Signaling Pathway Using the Tobacco Transient Expression System

Visualization of dynamic signaling events in live cells has been a challenge. We expanded an established transient expression system, the biomolecular fluorescent complementation (BiFC) assay in tobacco epidermal cells, from testing protein-protein interaction to monitoring spatial distribution of signal transduction in plant cells. In this protocol, we used the BiFC assay to show that the interaction and the signaling between the Arabidopsis MAPKKK YODA and MAPK6 occur at the plasma membrane. When the scaffold protein BASL was co-expressed, the YODA-MAPK interaction redistributed and spatially co-polarized with CFP-BASL. This modified tobacco expression system allows for quick examination of signaling localization and dynamic changes (less than 4 days) and can accommodate multiple of fluorescent protein colors (at least three). We also presented detailed methods to quantify protein distribution (asymmetric spatial localization, or &#34;polarization&#34;) in tobacco cells. This advanced tobacco expression system has a potential to be used widely for quick testing of dynamic signaling events in live plant cells.

At the subcellular level, signaling events are dynamically modulated by developmental and environmental cues. Here we describe a protocol that employs the tobacco transient expression system to monitor dynamic protein-protein interaction and to disclose spatial organization of signal transduction in plant cells.

Visualization of dynamic signaling events in live cells has been a challenge. We expanded an established transient expression system, the biomolecular ...

Studying the Protein Quality Control System of D. discoideum Using Temperature-controlled Live Cell Imaging

The complex lifestyle of the social amoebae Dictyostelium discoideum makes it a valuable model for the study of various biological processes. Recently, we showed that D. discoideum is remarkably resilient to protein aggregation and can be used to gain insights into the cellular protein quality control system. However, the use of D. discoideum as a model system poses several challenges to microscopy-based experimental approaches, such as the high motility of the cells and their susceptibility to photo-toxicity. The latter proves to be especially challenging when studying protein homeostasis, as the phototoxic effects can induce a cellular stress response and thus alter to behavior of the protein quality control system. 
Temperature increase is a commonly used way to induce cellular stress. Here, we describe a temperature-controllable imaging protocol, which allows observing temperature-induced perturbations in D. discoideum. Moreover, when applied at normal growth temperature, this imaging protocol can also noticeably reduce photo-toxicity, thus allowing imaging with higher intensities. This can be particularly useful when imaging proteins with very low expression levels. Moreover, the high mobility of the cells often requires the acquisition of multiple fields of view to follow individual cells, and the number of fields needs to be balanced against the desired time interval and exposure time.

Studying the Protein Quality Control System of D. discoideum Using Temperature-controlled Live Cell Imaging

The social amoebae Dictyostelium discoideum has recently been established as a system to study protein misfolding and proteostasis. Here, we describe a new imaging-based methodology to study temperature-induced protein aggregation and the cellular stress response in D. discoideum.

The complex lifestyle of the social amoebae Dictyostelium discoideum makes it a valuable model for the study of various biological processes. Recently, we ...

A Rapid Automated Protocol for Muscle Fiber Population Analysis in Rat Muscle Cross Sections Using Myosin Heavy Chain Immunohistochemistry

Quantification of muscle fiber populations provides a deeper insight into the effects of disease, trauma, and various other influences on skeletal muscle composition. Various time-consuming methods have traditionally been used to study fiber populations in many fields of research. However, recently developed immunohistochemical methods based on myosin heavy chain protein expression provide a quick alternative to identify multiple fiber types in a single section. Here, we present a rapid, reliable and reproducible protocol for improved staining quality, allowing automatic acquisition of whole cross sections and automatic quantification of fiber populations with ImageJ. For this purpose, embedded skeletal muscles are cut in cross sections, stained using myosin heavy chains antibodies with secondary fluorescent antibodies and DAPI for cell nuclei staining. Whole cross sections are then scanned automatically using a slide scanner to obtain high-resolution composite pictures of the entire specimen. Fiber population analyses are subsequently performed to quantify slow, intermediate and fast fibers using an automated macro for ImageJ. We have previously shown that this method can identify fiber populations reliably to a degree of &#177;4%. In addition, this method reduces inter-user variability and time per analyses significantly using the open source platform ImageJ.

Here, we present a protocol for rapid muscle fiber analyses, which allows improved staining quality, and thereby automatic acquisition and quantification of fiber populations using the freely available software ImageJ.

Quantification of muscle fiber populations provides a deeper insight into the effects of disease, trauma, and various other influences on skeletal muscle ...