The authors would like to acknowledge the Vanderbilt High Throughput Screening Core for the use of their facilities, Agilent Biotechnologies, Dr. Paul Kievit (Oregon Health and Science University) for non-human primate islet isolations, and Eric Donahue (Vanderbilt University) for assistance with Figure 1. J.M.E. was supported by NIGMS of the National Institutes of Health under award number T32GM007347. M.G. was supported by the NIH/NIDDK (R24DK090964-06) and the Department of Veterans Affairs (BX003744).

1. Preparation of Microplate and Sensor Cartridge on the Day Prior to Running the Assay
Islets were isolated from three year old Japanese macaques as previously described13. This method is very similar to that used to isolate human islets from cadaver donors, but differs from mice, in which pancreata are often inflated with collagenase solution while the animal is under sedation and prior to organ removal. Islet retrieval was conducted in accordance with the guidelines of the Institutional Animal Care and Use Committee (IACUC) of the Oregon National Primate Research Center (ONPRC) and Oregon Health and Science University and were approved by the ONPRC IACUC. The ONPRC abides by the Animal Welfare Act and Regulations enforced by the United States Department of Agriculture (USDA) and the Public Health Service Policy on Humane Care and Use of Laboratory Animals in accordance with the Guide for the Care and Use of Laboratory Animals published by the National Institutes of Health.
<ol>
	<li>Preparation of Spheroid Microplate
	<ol>
		<li>Prepare 3 mL of a 0.1M solution of sodium bicarbonate. Filter sterilize the solution. We utilized a 0.45 &#181;m filter (Table of Materials).</li>
		<li>In a cell culture hood, add 200 &#181;L of cell and tissue adhesive (Table of Materials) to 2.8 mL of 0.1M sodium bicarbonate. Then, add 20 &#181;L of this solution to the bottom of each well of the 96-well spheroid microplate (Table of Materials). Ensure that air bubbles are removed from the pipet tip and only the bottom of the plate is covered. Coating of the microplate prevents islets from moving up the sides of the wells when drugs are added and mixed into the well during the assay. 
		NOTE: It is only necessary to coat as many wells as will be used for islets when the assay is run. If only a few wells will be used, the cell adhesive solution can be scaled down appropriately. The cell adhesive used in the assay is a formulated protein solution extracted from the marine mussel. Alternatively, microplate wells can be coated with 20 &#181;L of 100 &#181;g/mL poly-D-lysine.</li>
		<li>Incubate the plate in a 37 &#176;C, non-CO2 incubator for one hour.</li>
		<li>In a sterile environment, aspirate cell adhesive solution from the plate. Wash each well two times with 400 &#181;L of 37 &#176;C sterile water using a multichannel pipet. Allow to air dry.</li>
		<li>After 30-40 minutes, cover the plate and store overnight at 4 &#176;C.</li>
	</ol>
	</li>
	<li>Hydration of the Sensor Cartridge
	<ol>
		<li>In a sterile environment, open the sensor cartridge package (Table of Materials) and remove the contents. Place the sensor cartridge upside down next to the utility plate.</li>
		<li>Fill each well of the utility plate with 200 &#181;L sterile water and lower the sensor cartridge back into the utility plate. Place assembled sensor cartridge and utility plate in a 37 &#176;C, non-CO2 incubator overnight.</li>
	</ol>
	</li>
	<li>Preparation of Calibrant
	<ol>
		<li>Aliquot 25 mL of calibrant (Table of Materials) into a 50 mL conical tube. Place tube in a 37 &#176;C, non-CO2 incubator overnight.</li>
	</ol>
	</li>
</ol>
2. Protocol for Media Preparation, Loading of Islets, and Loading of Sensor Cartridge on the Day of Assay
<ol>
	<li>Preparation of media
	<ol>
		<li>To 48.5 mL of base media (minimal DMEM, see Table of Materials), add 500 &#181;L each of 1 mM sodium pyruvate and 2 mM glutamine. Additionally, add 496 &#181;L of 200 mg/ml glucose (final concentration of glucose in the media is 5.5 mM). 
		NOTE: Baseline glucose concentration was kept constant for these experiments. However, glucose can also be used to stimulate respiration in addition to the pharmacologic manipulations described blow10.</li>
		<li>Confirm that the pH is 7.4 +/- 0.1, adjusting if necessary.</li>
	</ol>
	</li>
	<li>Preparation of sensor cartridge
	<ol>
		<li>Take sensor cartridge out of incubator, remove sensor cartridge lid, and dump out water from wells. Place 200 mL of pre-warmed calibrant into each well and replace sensor cartridge lid.</li>
		<li>Place sensor cartridge back in incubator for about 1 hour (until needed).</li>
	</ol>
	</li>
	<li>Preparation of drugs for mitochondrial stress assay
	<ol>
		<li>Open the stress test kit (Table of Materials) and remove the contents. Make up stock and working solutions for Oligomycin, Carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP), and Rotenone/Antimycin A (AA) as follows.
		<ol>
			<li>Oligomycin: add 630 &#181;L of assembled media to tube to make 100 &#181;M stock. Then, dilute to 45 &#181;M with media to obtain port concentration (final well concentration after injection will be 4.5 &#181;M)</li>
			<li>FCCP: add 720 &#181;L of assembled media to tube to make 100 &#181;M stock. Dilute to 10 &#181;M with media to obtain port concentration (final well concentration will be 1 &#181;M) 
			NOTE: BSA and/or FBS should not be added to media, as this can affect the action of mitochondrial uncouplers14.</li>
			<li>Rotenone/AA: add 540 &#181;L of assembled media to tube to make 50 &#181;M stock. Dilute to 25 &#181;M with media to obtain port concentration (final well concentration will be 2.5 &#181;M) 
			NOTE: The above concentrations have produced consistent results in our hands. Additional FCCP led to no further increase in respiration. However, drug concentrations may need to be adjusted depending on islet size, and especially with islets from different species or non-islet spheroids. For reference, the average diameter of a non-human primate islet is about 150 &#181;m15.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Preparation of spheroid plate and transfer of islets
	<ol>
		<li>Hand-pick pancreatic islets into a 60 mm x 15 mm cell culture dish containing assembled media to obtain near 100% purity. 
		NOTE: Islets should appear rounded, with a clearly defined periphery, and appear denser than exocrine tissue contaminants. Avoid islets that appear damaged or frayed. In this experiment, islet size was not directly measured, although we attempted to pick islets of approximately equivalent size for each well and sample.</li>
		<li>Load each well of spheroid microplate with 175 &#181;L of assembled media using a multichannel pipette.</li>
		<li>Using a P20 pipette set to 15 &#181;L, aspirate 15 islets from cell culture dish. Islets should be visible in the pipette tip to the naked eye.</li>
		<li>To transfer islets to spheroid microplate, lower pipette tip to the bottom of the well, barely lift up, and slowly pipette out a very small volume (~5 &#181;L). Confirm that all islets have left the pipette tip. Each well should receive 15 islets. Occasionally check spheroid microplate under the microscope to verify that islets are at the bottom of each well rather than stuck to the sides. 
		NOTE: Avoid loading the corner wells with islets. Oxygen and pH flux out of the plastic can occur during the assay, and this is exacerbated in the four corner wells.</li>
		<li>Once all islets have been transferred to the spheroid microplate, incubate the microplate in a 37 &#176;C, non-CO2 incubator while completing the steps below.</li>
	</ol>
	</li>
	<li>Loading the sensor cartridge and running the assay
	<ol>
		<li>Remove sensor cartridge from incubator. Ports A-C for each well must be loaded with either drug or media. Wells containing islets and the four corner wells should be loaded with drug. Non-corner wells without islets should be loaded with media. Port D can be left empty. Load port A (top left of each sensor) with 20 &#181;L of oligomycin or media. Load port B (top right) with 22 &#181;L of FCCP or media. Load port C (bottom left) with 25 &#181;L of Rotenone/AA or media.</li>
		<li>Program an extracellular flux analyzer assay for a 30 minute baseline respiration period (5 cycles of 3 minute mix, 3 minute measure), 42 minute oligomycin measurement period (7 cycles of 3 minute mix, 3 minute measure), 30 minutes FCCP (5 cycles of 3 minute mix, 3 minute measure), and 30 minutes Rotenone/AA (5 cycles of 3 minute mix, 3 minute measure).</li>
		<li>Run the assay and follow instructions on screen for calibrating the sensor and inserting the microplate.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Mulder, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcribing+&#946;-cell+mitochondria+in+health+and+disease.">Transcribing &#946;-cell mitochondria in health and disease.</a> Molecular Metabolism. 6 (9), 1040-1051 (2017).</li><li>Maechler, P., Wollheim, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitochondrial+signals+in+glucose-stimulated+insulin+secretion+in+the+beta+cell.">Mitochondrial signals in glucose-stimulated insulin secretion in the beta cell.</a> The Journal of Physiology. 529 (Pt 1), 49-56 (2000).</li><li>Curry, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glucagon+Potentiation+of+Insulin+Secretion+by+the+Perfused+Rat+Pancreas.">Glucagon Potentiation of Insulin Secretion by the Perfused Rat Pancreas.</a> Diabetes. 19 (6), 420 (1970).</li><li>Song, G., Pacini, G., Ahr&#233;n, B., D'Argenio, D. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glucagon+Increases+Insulin+Levels+by+Stimulating+Insulin+Secretion+Without+Effect+on+Insulin+Clearance+in+Mice.">Glucagon Increases Insulin Levels by Stimulating Insulin Secretion Without Effect on Insulin Clearance in Mice.</a> Peptides. 88, 74-79 (2017).</li><li>Vergari, E., 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=Insulin+inhibits+glucagon+release+by+SGLT2-induced+stimulation+of+somatostatin+secretion.">Insulin inhibits glucagon release by SGLT2-induced stimulation of somatostatin secretion.</a> Nature Communications. 10 (1), 139 (2019).</li><li>Watts, M., Ha, J., Kimchi, O., Sherman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Paracrine+regulation+of+glucagon+secretion:+the+&#946;/&#945;/&#948;+model.">Paracrine regulation of glucagon secretion: the &#946;/&#945;/&#948; model.</a> American Journal of Physiology--Endocrinology and Metabolism. 310 (8), E597-E611 (2016).</li><li>Sweet, I. 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=Continuous+measurement+of+oxygen+consumption+by+pancreatic+islets.">Continuous measurement of oxygen consumption by pancreatic islets.</a> Diabetes Technology &amp; Therapeutics. 4 (5), 661-672 (2002).</li><li>. Agilent Seahorse XF Instruments Overview and Selection Guide Available from: <a target="_blank" href="https://www.agilent.com/en/products/cell-analysis/seahorse-xf-instruments-selection-guide">https://www.agilent.com/en/products/cell-analysis/seahorse-xf-instruments-selection-guide</a> (2019)</li><li>Wikstrom, J. 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=A+novel+high-throughput+assay+for+islet+respiration+reveals+uncoupling+of+rodent+and+human+islets.">A novel high-throughput assay for islet respiration reveals uncoupling of rodent and human islets.</a> PLoS One. 7 (5), e33023 (2012).</li><li>Taddeo, E. P., 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=Individual+islet+respirometry+reveals+functional+diversity+within+the+islet+population+of+mice+and+human+donors.">Individual islet respirometry reveals functional diversity within the islet population of mice and human donors.</a> Molecular Metabolism. 16, 150-159 (2018).</li><li>Conrad, E., 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+MAFB+transcription+factor+impacts+islet+alpha-cell+function+in+rodents+and+represents+a+unique+signature+of+primate+islet+beta-cells.">The MAFB transcription factor impacts islet alpha-cell function in rodents and represents a unique signature of primate islet beta-cells.</a> American Journal of Physiology--Endocrinology and Metabolism. 310 (1), E91-E102 (2016).</li><li>Steiner, D. J., Kim, A., Miller, K., Hara, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pancreatic+islet+plasticity:+interspecies+comparison+of+islet+architecture+and+composition.">Pancreatic islet plasticity: interspecies comparison of islet architecture and composition.</a> Islets. 2 (3), 135-145 (2010).</li><li>Elsakr, J. M., 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=Maternal+Western-style+diet+affects+offspring+islet+composition+and+function+in+a+non-human+primate+model+of+maternal+over-nutrition.">Maternal Western-style diet affects offspring islet composition and function in a non-human primate model of maternal over-nutrition.</a> Molecular Metabolism. , (2019).</li><li>Soutar, M. P. M., 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=FBS/BSA+media+concentration+determines+CCCP's+ability+to+depolarize+mitochondria+and+activate+PINK1-PRKN+mitophagy.">FBS/BSA media concentration determines CCCP's ability to depolarize mitochondria and activate PINK1-PRKN mitophagy.</a> Autophagy. , 1-10 (2019).</li><li>Hirshberg, 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=Pancreatic+Islet+Transplantation+Using+the+Nonhuman+Primate+(Rhesus)+Model+Predicts+That+the+Portal+Vein+Is+Superior+to+the+Celiac+Artery+as+the+Islet+Infusion+Site.">Pancreatic Islet Transplantation Using the Nonhuman Primate (Rhesus) Model Predicts That the Portal Vein Is Superior to the Celiac Artery as the Islet Infusion Site.</a> Diabetes. 51 (7), 2135-2140 (2002).</li><li>Divakaruni, A. S., Paradyse, A., Ferrick, D. A., Murphy, A. N., Jastroch, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+and+interpretation+of+microplate-based+oxygen+consumption+and+pH+data.">Analysis and interpretation of microplate-based oxygen consumption and pH data.</a> Methods in Enzymology. 547, 309-354 (2014).</li><li>Papas, K. 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=Islet+Oxygen+Consumption+Rate+(OCR)+Dose+Predicts+Insulin+Independence+in+Clinical+Islet+Autotransplantation.">Islet Oxygen Consumption Rate (OCR) Dose Predicts Insulin Independence in Clinical Islet Autotransplantation.</a> PLoS One. 10 (8), e0134428 (2015).</li></ol>

The authors have nothing to disclose.

The study of islet oxygen consumption has previously been hampered by the spherical shape of islets, their lack of adherence to culture surfaces, and the number of islets required per well. In this protocol, we highlight the efficacy of the 96-well spheroid microplate for measuring islet oxygen consumption on a small number of islets and demonstrate a technique for handling and loading islets which is technically feasible and produces consistent results.
In order for islets to adhere to the bo...

In order to maintain normal blood glucose levels, the pancreatic &#946; cell must sense elevations in glucose and secrete insulin accordingly. The coupling of insulin secretion with glucose levels is directly linked to glucose metabolism and the production of ATP through mitochondrial oxidative phosphorylation. Thus, mitochondria play a critical role in stimulus-secretion coupling1. Assessing &#946;-cell mitochondrial function can reveal defects that lead to impaired insulin secretion. The secretion of glucagon by pancreatic &#945; cells is also closely tied to mitochondrial function2. Although immortalized islet cell lines have proven useful for some types of assays, the physiology of these cells does not accurately recapitulate whole islet function, as illustrated by the potentiation of insulin secretion by glucagon3,4 and the inhibition of glucagon secretion by insulin/somatostatin5,6 in intact islets. This demonstrates the need for measuring oxygen consumption using whole, intact islets.
Techniques for the measurement of islet cell respirometry have evolved over time, from the use of oxygen-sensitive fluorescent dyes7 to solid-state sensors that directly measure oxygen consumption8. Initially designed for monolayer, adherent cells, commonly used cell culture plate systems have proven to be ineffective for pancreatic islets. As islets do not naturally adhere to the wells, they are prone to being pushed to the periphery of the culture well resulting in inaccurate measurement of oxygen consumption9. To combat this problem, specialized 24-well plates with a central depression that could contain islets were developed9. However, the 24-well plate system was limited by the large number of islets required (50-80 per well) and the number of conditions that could be tested simultaneously10. The recent development of 96-well microplates designed specifically for extracellular flux analysis in spheroids has overcome these barriers, enabling the measurement of islet respirometry with 20 or fewer islets per well10.
Here, we demonstrate the use of this system to measure oxygen consumption in islets from the Japanese macaque (Macaca fuscata), an animal model with similar islet biology to humans11,12. In this protocol, 15 macaque islets are analyzed per well. In our hands, 15 islets per well produced higher baseline oxygen consumption than fewer islets, with robust activation and repression of respiration in response to pharmacologic manipulation. We highlight the steps to prepare for the assay, an effective method for consistent loading of islets at the center of each well, and common challenges when performing this assay.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Cell culture dish, 60 mm X 15 mm style</td>
			<td>Corning</td>
			<td>430166</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell-Tak Cell and Tissue Adhesive</td>
			<td>Corning</td>
			<td>354240</td>
			<td></td>
		</tr>
		<tr>
			<td>Conical tube, 50 mL</td>
			<td>Falcon</td>
			<td>352070</td>
			<td></td>
		</tr>
		<tr>
			<td>Dextrose anhydrous</td>
			<td>Fisher Scientific</td>
			<td>BP350-1</td>
			<td>For glucose solution, 200 mg/ml, sterile filetered</td>
		</tr>
		<tr>
			<td>Disposable reservoirs (sterile), 25 ML</td>
			<td>Vistalab</td>
			<td>3054-1033</td>
			<td>for loading multichannel pipet</td>
		</tr>
		<tr>
			<td>EZFlow Sterile 0.45 &#956;m PES Syringe Filter, 13 mm</td>
			<td>Foxx Life Sciences</td>
			<td>371-3115-OEM</td>
			<td></td>
		</tr>
		<tr>
			<td>L-glutamine</td>
			<td>Gibco</td>
			<td>25030-081</td>
			<td>200 mM (100x)</td>
		</tr>
		<tr>
			<td>Multichannel pipette tips</td>
			<td>ThermoFisher Scientific</td>
			<td>94410810</td>
			<td></td>
		</tr>
		<tr>
			<td>Multichannel pipette, 15-1250 &#956;L</td>
			<td>ThermoFisher Scientific</td>
			<td>4672100BT</td>
			<td>Recommended</td>
		</tr>
		<tr>
			<td>P20, P200, and P1000 pipettes</td>
			<td>Eppendorf</td>
			<td>2231000602</td>
			<td></td>
		</tr>
		<tr>
			<td>pH Probe</td>
			<td>Hanna Instruments</td>
			<td>HI2210-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette tips, 20 &#956;L, 200 &#956;L, 1000 &#956;L</td>
			<td>Olympus</td>
			<td>24-404, 24-412, 24-430</td>
			<td></td>
		</tr>
		<tr>
			<td>Seahorse XF Base Media</td>
			<td>Agilent</td>
			<td>103334-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Seahorse XF Cell Mito Stress Test Kit</td>
			<td>Agilent</td>
			<td>103015-100</td>
			<td>Includes Oligomycin, FCCP, and Rotenone/Antimycin A</td>
		</tr>
		<tr>
			<td>Seahorse XFe96 Analyzer</td>
			<td>Agilent</td>
			<td>S7800B</td>
			<td>Including prep station with 37 &#176;C non-CO2 incubator</td>
		</tr>
		<tr>
			<td>Seahorse XFe96 Spheroid Fluxpak Mini</td>
			<td>Agilent</td>
			<td>102905-100</td>
			<td>Includes sensor cartridge, spheroid microplate, and calibrant</td>
		</tr>
		<tr>
			<td>Sodium bicarbonate</td>
			<td>Fisher Scientific</td>
			<td>BP328-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium pyruvate</td>
			<td>Gibco</td>
			<td>11360-070</td>
			<td>100 mM (100x)</td>
		</tr>
		<tr>
			<td>Stereo Microscope</td>
			<td>Olympus</td>
			<td>SZX9</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe (sterile), 5 mL</td>
			<td>BD</td>
			<td>309603</td>
			<td>For sterile filtration</td>
		</tr>
		<tr>
			<td>Water (sterile)</td>
			<td>Sigma</td>
			<td>W3500-500mL</td>
			<td></td>
		</tr>
	</tbody>
</table>

analysis of non-human primate pancreatic islet oxygen consumption

The measurement of oxygen consumption in spheroid clusters of cells, such as ex vivo pancreatic islets, has historically been challenging. We demonstrate the measurement of islet oxygen consumption using a 96-well microplate designed for the measurement of oxygen consumption in spheroids. In this assay, spheroid microplates are coated with a cell and tissue adhesive on the day prior to the assay. We utilize a small volume of adhesive solution to encourage islet adherence to only the bottom of the well. On the day of the assay, 15 islets are loaded directly into the base of each well using a technique that ensures optimal positioning of islets and accurate measurement of oxygen consumption. Various aspects of mitochondrial respiration are probed pharmacologically in non-human primate islets, including ATP-dependent respiration, maximal respiration, and proton leak. This method allows for consistent, reproducible results using only a small number of islets per well. It can theoretically be applied to any cultured spheroids of similar size.

To load islets into microplate, 15 islets should be aspirated in 15 &#181;L of media, as shown in Figure 1A. Islets will naturally settle toward the bottom of the pipet tip within a few seconds. Then, the pipet tip is lowered to the bottom of the well. The tip is very slightly lifted, and a small volume (about 5 &#181;L) is pipetted out along with the islets. This technique results in consistent placement of islet at the bottom of the micropl...

Watch this Scientific Journal Video about Analysis of Non-Human Primate Pancreatic Islet Oxygen Consumption at JoVE.com

Analysis of Non-Human Primate Pancreatic Islet Oxygen Consumption

This protocol demonstrates the accurate and reproducible measurement of oxygen consumption in non-human primate pancreatic islets. The islet loading techniques and coating of the microplate provide a framework for efficient measurement of respiration in other types of cultured spheroids.

The measurement of oxygen consumption in spheroid clusters of cells, such as ex vivo pancreatic islets, has historically been challenging. We demonstrate ...

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5.4K Views.  Vanderbilt University. This protocol demonstrates the accurate and reproducible measurement of oxygen consumption in non-human primate pancreatic islets. The islet loading techniques and coating of the microplate provide a framework for efficient measurement of respiration in other types of cultured spheroids.

Video: Analysis of Non-Human Primate Pancreatic Islet Oxygen Consumption

Direct Induction of Hemogenic Endothelium and Blood by Overexpression of Transcription Factors in Human Pluripotent Stem Cells

During development, hematopoietic cells arise from a specialized subset of endothelial cells, hemogenic endothelium (HE). Modeling HE development in vitro is essential for mechanistic studies of the endothelial-hematopoietic transition and hematopoietic specification. Here, we describe a method for the efficient induction of HE from human pluripotent stem cells (hPSCs) by way of overexpression of different sets of transcription factors. The combination of ETV2 and GATA1 or GATA2 TFs is used to induce HE with pan-myeloid potential, while a combination of GATA2 and TAL1 transcription factors allows for the production of HE with erythroid and megakaryocytic potential. The addition of LMO2 to GATA2 and TAL1 combination substantially accelerates differentiation and increases erythroid and megakaryocytic cells production. This method provides an efficient and rapid means of HE induction from hPSCs and allows for the observation of the endothelial-hematopoietic transition in a culture dish. The protocol includes hPSCs transduction procedures and post-transduction analysis of HE and blood progenitors.

This protocol describes the efficient induction of hemogenic endothelium and multipotential hematopoietic progenitors from human pluripotent stem cells via the forced expression of transcription factors.

During development, hematopoietic cells arise from a specialized subset of endothelial cells, hemogenic endothelium (HE). Modeling HE development in vitro ...

Efficient Differentiation of Pluripotent Stem Cells to NKX6-1+ Pancreatic Progenitors

Pluripotent stem cells have the ability to self renew and differentiate to multiple lineages, making them an attractive source for the generation of pancreatic progenitor cells that can be used for the study of and future treatment of diabetes. This article outlines a four-stage differentiation protocol designed to generate pancreatic progenitor cells from human embryonic stem cells (hESCs). This protocol can be applied to a number of human pluripotent stem cell (hPSC) lines. The approach taken to generate pancreatic progenitor cells is to differentiate hESCs to accurately model key stages of pancreatic development. This begins with the induction of the definitive endoderm, which is achieved by culturing the cells in the presence of Activin A, basic Fibroblast Growth Factor (bFGF) and CHIR990210. Further differentiation and patterning with Fibroblast Growth Factor 10 (FGF10) and Dorsomorphin generates cells resembling the posterior foregut. The addition of Retinoic Acid, NOGGIN, SANT-1 and FGF10 differentiates posterior foregut cells into cells characteristic of pancreatic endoderm. Finally, the combination of Epidermal Growth Factor (EGF), Nicotinamide and NOGGIN leads to the efficient generation of PDX1+/NKX6-1+ cells. Flow cytometry is performed to confirm the expression of specific markers at key stages of pancreatic development. The PDX1+/NKX6-1+ pancreatic progenitors at the end of stage 4 are capable of generating mature &#946; cells upon transplantation into immunodeficient mice and can be further differentiated to generate insulin-producing cells in vitro. Thus, the efficient generation of PDX1+/NKX6-1+ pancreatic progenitors, as demonstrated in this protocol, is of great importance as it provides a platform to study human pancreatic development in vitro and provides a source of cells with the potential of differentiating to &#946; cells that could eventually be used for the treatment of diabetes.

Efficient Differentiation of Pluripotent Stem Cells to NKX6-1+ Pancreatic Progenitors

Here we describe a 4-stage protocol to differentiate human embryonic stem cells to NKX6-1+ pancreatic progenitors in vitro. This protocol can be applied to a variety of human pluripotent stem cell lines.

Pluripotent stem cells have the ability to self renew and differentiate to multiple lineages, making them an attractive source for the generation of ...

Evaluation of Intracellular Location of Reactive Oxygen Species in Solea Senegalensis Spermatozoa

Oxidative stress is one of the important factors in decreasing sperm quality. Developing efficient protocols for detecting reactive oxygen species (ROS) in spermatozoa is of high importance in any species, but these methods are rarely used and even less in teleost. Cryopreservation is a useful technique in aquaculture for different purposes, including gene banking and guaranteed sperm availability throughout the year. Freezing/thawing procedures could cause ROS production and damage the sperm cells. Considering the prospective damage that an excess of ROS production could cause in spermatozoa depending on their localization, here a detailed methodology to detect H2O2 and to evaluate its intracellular localization by confocal microscopy is provided. For this purpose, a combination of 3 fluorochromes (2&#8242;,7&#8242;-Dichlorodihydrofluorescein diacetate (DCFH-DA), a live mitochondria stain and 4&#8242;,6-Diamidino-2-phenylindole dihydrochloride (DAPI)) are used to evaluate the co-localization of H2O2 with spermatozoa nuclei or mitochondria in Solea senegalesis sperm samples.

Evaluation of Intracellular Location of Reactive Oxygen Species in Solea Senegalensis Spermatozoa

This protocol describes a detailed methodology for detecting H2O2 localization within Solea senegalensis spermatozoa using a sensitive fluorochrome DCFH-DA for ROS, a live mitochondria stain for mitochondria, and DAPI for nuclei visualization, respectively. The protocol is designed to be performed within 2 h with either fresh or thawed spermatozoa.

Oxidative stress is one of the important factors in decreasing sperm quality. Developing efficient protocols for detecting reactive oxygen species (ROS) ...

Generation of Scaffold-free, Three-dimensional Insulin Expressing Pancreatoids from Mouse Pancreatic Progenitors In Vitro

The pancreas is a complex organ composed of many different cell types that work together to regulate blood glucose homeostasis and digestion. These cell types include enzyme-secreting acinar cells, an arborized ductal system responsible for the transportation of enzymes to the gut, and hormone-producing endocrine cells. 
Endocrine beta-cells are the sole cell type in the body that produce insulin to lower blood glucose levels. Diabetes, a disease characterized by a loss or the dysfunction of beta-cells, is reaching epidemic proportions. Thus, it is essential to establish protocols to investigate beta-cell development that can be used for screening purposes to derive the drug and cell-based therapeutics. While the experimental investigation of mouse development is essential, in vivo studies are laborious and time-consuming. Cultured cells provide a more convenient platform for screening; however, they are unable to maintain the cellular diversity, architectural organization, and cellular interactions found in vivo. Thus, it is essential to develop new tools to investigate pancreatic organogenesis and physiology.
Pancreatic epithelial cells develop in the close association with mesenchyme from the onset of organogenesis as cells organize and differentiate into the complex, physiologically competent adult organ. The pancreatic mesenchyme provides important signals for the endocrine development, many of which are not well understood yet, thus difficult to recapitulate during the in vitro culture. Here, we describe a protocol to culture three-dimensional, cellular complex mouse organoids that retain mesenchyme, termed pancreatoids. The e10.5 murine pancreatic bud is dissected, dissociated, and cultured in a scaffold-free environment. These floating cells self-assemble with mesenchyme enveloping the developing pancreatoid and a robust number of endocrine beta-cells developing along with the acinar and the duct cells. This system can be used to study the cell fate determination, structural organization, and morphogenesis, cell-cell interactions during organogenesis, or for the drug, small molecule, or genetic screening.

Generation of Scaffold-free, Three-dimensional Insulin Expressing Pancreatoids from Mouse Pancreatic Progenitors In Vitro

Here, we present a protocol to generate insulin expressing 3D murine pancreatoids from free-floating e10.5 dissociated pancreatic progenitors and the associated mesenchyme.

The pancreas is a complex organ composed of many different cell types that work together to regulate blood glucose homeostasis and digestion. These cell ...

Efficient Generation of Pancreas/Duodenum Homeobox Protein 1+ Posterior Foregut/Pancreatic Progenitors from hPSCs in Adhesion Cultures

Human pluripotent stem cell (hPSC)-derived pancreatic cells are a promising cell source for regenerative medicine and a platform to study human developmental processes. Stepwise directed differentiation that recapitulates developmental processes is one of the major ways to generate pancreatic cells including pancreas/duodenum homeobox protein 1+ (PDX1+) pancreatic progenitor cells. Conventional protocols initiate the differentiation with small colonies shortly after the passage. However, in the state of colonies or aggregates, cells are prone to heterogeneities, which might hamper the differentiation to PDX1+ cells. Here, we present a detailed protocol to differentiate hPSCs into PDX1+ cells. The protocol consists of four steps and initiates the differentiation by seeding dissociated single cells. The induction of SOX17+ definitive endoderm cells was followed by the expression of two primitive gut tube markers, HNF1&#946; and HNF4&#945;, and eventual differentiation into PDX1+ cells. The present protocol provides easy handling and may improve and stabilize the differentiation efficiency of some hPSC lines that were previously found to differentiate inefficiently into endodermal lineages or PDX1+ cells.

Efficient Generation of Pancreas/Duodenum Homeobox Protein 1+ Posterior Foregut/Pancreatic Progenitors from hPSCs in Adhesion Cultures

Here, we present a detailed protocol to differentiate human pluripotent stem cells (hPSCs) into pancreas/duodenum homeobox protein 1+ (PDX1+) cells for the generation of pancreatic lineages based on the non-colony type monolayer growth of dissociated single cells. This method is suitable for producing homogenous hPSC-derived cells, genetic manipulation and screening.

Human pluripotent stem cell (hPSC)-derived pancreatic cells are a promising cell source for regenerative medicine and a platform to study human ...

Single-cell Transcriptomic Analyses of Mouse Pancreatic Endocrine Cells

Pancreatic endocrine cells, which are clustered in islets, regulate blood glucose stability and energy metabolism. The distinct cell types in islets, including insulin-secreting &#946; cells, are differentiated from common endocrine progenitors during the embryonic stage. Immature endocrine cells expand via cell proliferation and mature during a long postnatal developmental period. However, the mechanisms underlying these processes are not clearly defined. Single-cell RNA-sequencing is a promising approach for the characterization of distinct cell populations and tracing cell lineage differentiation pathways. Here, we describe a method for the single-cell RNA-sequencing of isolated pancreatic &#946; cells from embryonic, neonatal and postnatal pancreases.

We describe a method for the isolation of endocrine cells from embryonic, neonatal and postnatal pancreases followed by single-cell RNA sequencing. This method allows analyses of pancreatic endocrine lineage development, cell heterogeneity and transcriptomic dynamics.

Pancreatic endocrine cells, which are clustered in islets, regulate blood glucose stability and energy metabolism. The distinct cell types in islets, ...

Differentiation of Human Pluripotent Stem Cells Into Pancreatic Beta-Cell Precursors in a 2D Culture System

Human pluripotent stem cells (hPSCs) are an excellent tool for studying early pancreatic development and investigating the genetic contributors to diabetes. hPSC-derived insulin-secreting cells can be generated for cell therapy and disease modeling,&#160;however,&#160;with limited efficiency and functional properties. hPSC-derived pancreatic progenitors that are precursors to beta cells and other endocrine cells, when co-express the two transcription factors PDX1 and NKX6.1, specify the progenitors to functional, insulin-secreting beta cells both in vitro and in vivo. hPSC-derived pancreatic progenitors are currently used for cell therapy in type 1 diabetes patients as part of clinical trials. However, current procedures do not generate a high proportion of NKX6.1 and pancreatic progenitors, leading to co-generation of non-functional endocrine cells and few glucose-responsive, insulin-secreting cells. This work thus developed an enhanced protocol for generating hPSC-derived pancreatic progenitors that maximize the co-expression of PDX1 and NKX6.1 in a 2D monolayer. The factors such as cell density, availability of fresh matrix, and dissociation of hPSC-derived endodermal cells are modulated that augmented PDX1 and NKX6.1 levels in the generated pancreatic progenitors and minimized commitment to alternate hepatic lineage. The study highlights that manipulating the cell&#39;s physical environment during in vitro differentiation can impact lineage specification and gene expression. Therefore, the current optimized protocol facilitates the scalable generation of PDX1 and NKX6.1 co-expressing progenitors for cell therapy and disease modeling.

The present protocol describes an enhanced method to increase the co-expression of PDX1 and NKX6.1 transcription factors in pancreatic progenitors derived from human pluripotent stem cells (hPSCs) in planar monolayers. This is achieved by replenishing the fresh matrix, manipulating cell density, and dissociating the endodermal cells.

Human pluripotent stem cells (hPSCs) are an excellent tool for studying early pancreatic development and investigating the genetic contributors to ...

Genetic Modification of Primate Cerebral Organoids

Targeted Microinjection and Electroporation of Primate Cerebral Organoids for Genetic Modification

The cerebral cortex is the outermost brain structure and is responsible for the processing of sensory input and motor output; it is seen as the seat of higher-order cognitive abilities in mammals, in particular, primates. Studying gene functions in primate brains is challenging due to technical and ethical reasons, but the establishment of the brain organoid technology has enabled the study of brain development in traditional primate models (e.g., rhesus macaque and common marmoset), as well as in previously experimentally inaccessible primate species (e.g., great apes), in an ethically justifiable and less technically demanding system. Moreover, human brain organoids allow the advanced investigation of neurodevelopmental and neurological disorders.
As brain organoids recapitulate many processes of brain development, they also represent a powerful tool to identify differences in, and to functionally compare, the genetic determinants underlying the brain development of various species in an evolutionary context. A great advantage of using organoids is the possibility to introduce genetic modifications, which permits the testing of gene functions. However, the introduction of such modifications is laborious and expensive. This paper describes a fast and cost-efficient approach to genetically modify cell populations within the ventricle-like structures of primate cerebral organoids, a subtype of brain organoids. This method combines a modified protocol for the reliable generation of cerebral organoids from human-, chimpanzee-, rhesus macaque-, and common marmoset-derived induced pluripotent stem cells (iPSCs) with a microinjection and electroporation approach. This provides an effective tool for the study of neurodevelopmental and evolutionary processes that can also be applied for disease modeling.

Author Spotlight: Targeted Microinjection and Electroporation of Primate Cerebral Organoids for Genetic Modification  

The electroporation of primate cerebral organoids provides a precise and efficient approach to introduce transient genetic modification(s) into different progenitor types and neurons in a model system close to primate (patho)physiological neocortex development. This allows the study of neurodevelopmental and evolutionary processes and can also be applied for disease modeling.

The cerebral cortex is the outermost brain structure and is responsible for the processing of sensory input and motor output; it is seen as the seat of ...

Differentiation of Human Pluripotent Stem Cells into Insulin-Producing Islet Clusters

Differentiation of human pluripotent stem cells (hPSCs) into insulin-secreting beta cells provides material for investigating beta cell function and diabetes treatment. However, challenges remain in obtaining stem cell-derived beta cells that adequately mimic native human beta cells. Building upon previous studies, hPSC-derived islet cells have been generated to create a protocol with improved differentiation outcomes and consistency. The protocol described here utilizes a pancreatic progenitor kit during Stages 1-4, followed by a protocol modified from a paper previously published in 2014 (termed "R-protocol" hereafter) during Stages 5-7. Detailed procedures for using the pancreatic progenitor kit and 400 &#181;m diameter microwell plates to generate pancreatic progenitor clusters, R-protocol for endocrine differentiation in a 96-well static suspension format, and in vitro characterization and functional evaluation of hPSC-derived islets, are included. The complete protocol takes 1 week for initial hPSC expansion followed by ~5 weeks to obtain insulin-producing hPSC islets. Personnel with basic stem cell culture techniques and training in biological assays can reproduce this protocol.

The differentiation of stem cells into islet cells provides an alternative solution to conventional diabetes treatment and disease modeling. We describe a detailed stem cell culture protocol that combines a commercial differentiation kit with a previously validated method to aid in producing insulin-secreting, stem cell-derived islets in a dish.

Differentiation of human pluripotent stem cells (hPSCs) into insulin-secreting beta cells provides material for investigating beta cell function and ...