We thank Irene Hernandez, Trudy Holyst, Dr. Hartmut Weiler (Versiti Blood Research Institute), and Dr. Leggy Arnold (University of Wisconsin-Milwaukee) for providing space and indirect support of this project, and Dr. John McCorvy (Medical College of Wisconsin) for pertinent advice. We thank the National Heart, Lung, and Blood Institute (R15HL127636), the U.S. Dept. of Defense (W81XWH22101), and the National Science Foundation (2223225) for grant support.

All media exchanges/additions made in steps 1 and 2 of the following protocol are performed in a sterile hood. Unless otherwise noted, all plasticware used in the sterile hood must be purchased sterilized and sealed or sterilized appropriately via autoclave.
1. Initiation of EA.hy926 cell line
<ol>
	<li>Acquire EA.hy926 cells.</li>
	<li>Store vial(s) of cells in the vapor phase of a liquid nitrogen tank.</li>
	<li>Prepare DMEM complete medium by first warming DMEM, FBS, and ...

Studying Protease-Activated Receptor Ligands in Endothelial Cells

While the previously reported protocol72 was generally reliable and allowed us to identify a new lead parmodulin, NRD-21,62 a more efficient protocol was desired. The assay was further compromised during the supply shortage caused by the COVID-19 pandemic. Acquiring tips for the automated liquid handler became difficult, and attempting to wash, sterilize, and reuse the tips produced CRCs with significant variance. This facilitated an urgent series of experiments designed to...

Protease-activated receptors (PARs)1,2,3 are a subfamily of class A G protein-coupled receptors (GPCRs) that are expressed in a variety of cell types, including platelets and endothelial cells4,5,6,7. Unlike the majority of GPCRs, PARs have a unique intramolecular mode of activation. Most GPCRs are activated by soluble ligands interacting with a distinct binding pocket, but PARs are activated by the proteolytic cleavage of the N-terminus, which results in a new tethered ligand that can interact with the extracellular loop 2 domain on the surface of a cell6,8,9. This interaction activates the receptor and can initiate several signaling pathways, promoting effects such as inflammation and platelet activation4,10,11,12. Different proteases can activate PARs through cleavage at unique sites on the N-terminus, revealing different tethered ligands (TL) that stabilize receptor conformations, which initiate different signaling pathways9,13,14,15. For example, in the most well-studied member of the subfamily, PAR1, cleavage by thrombin is used to support numerous biological processes, including platelet activation and leukocyte recruitment to the endothelium, but can lead to deleterious effects when the receptor is overexpressed or overactivated4,16,17,18,19,20,21. Conversely, cleavage by activated protein C (aPC) can promote anti-inflammatory effects and maintenance of endothelial barriers15,22,23,24,25,26,27,28,29. PARs can also be activated by peptide analogs of the TLs in an intermolecular fashion13,30,31. These peptides are routinely used to measure PAR inhibition (modulation) in place of PAR-targeting proteases, and they are used in this protocol.
Numerous disorders are associated with pathological PAR1 signaling, including sepsis22,32, cardiovascular disease33,34,35,36,37,38, kidney disease39,40,41,42, sickle cell disease43, fibrosis44, osteoporosis and osteoarthritis45,46, neurodegeneration47,48,49,50,51, and cancer52,53,54,55,56,57,58,59. Antagonists of PAR1 have been studied since the 1990s as antiplatelet agents for cardiovascular disease, and the growing list of diseases associated with the receptor necessitates the identification of novel ligands for use as biological probes (tool compounds) or as potential therapeutics. Currently, there is only one FDA-approved PAR1 antagonist, vorapaxar, which is used to treat coronary artery disease in high-risk patients34,36,37,60. An alternative PAR1 antagonist, the pepducin PZ-128, completed a successful phase II study to prevent thrombosis in cardiac catheterization patients38. The Dockendorff group has focused on the medicinal chemistry and pharmacology of a separate class of small molecules, PAR1 ligands known as parmodulins61,62. Unlike reported PAR1 antagonists such as vorapaxar, parmodulins are allosteric, biased modulators of PAR1 that selectively block the G&#945;q pathway while promoting cytoprotective effects similar to aPC. Unlike potent orthosteric PAR1 antagonists such as vorapaxar, published parmodulins are also reversible63,64,65.
Initially, parmodulins were identified by Flaumenhaft and coworkers for&#160;their ability to inhibit P-selectin expression or granule secretion in platelets61,66. However, an alternative method was required to study the effects of parmodulins on endothelial cells. One common method to monitor GPCR-related signaling is to measure intracellular Ca2+ mobilization, an important secondary messenger that can be measured using a suitable intracellular calcium-binding dye67,68. Substantial evidence has been provided showing that calcium mobilization induced by PAR1 is through the activation of G&#945;q69,70. Once activated by its tethered ligand (or a suitable exogenous ligand), PAR1 undergoes a conformational change which causes guanosine diphosphate (GDP) bound to the G&#945;q subunit to be replaced by guanosine triphosphate (GTP)68. The G&#945;q subunit then activates phospholipase C&#946; (PLC-&#946;), which catalyzes the hydrolysis of phosphatidylinositol 4,5 bisphosphate (PIP2), forming 1,4,5-inositol triphosphate (IP3) and diacylglycerol (DAG). Finally, IP3 binds to IP3-sensitive Ca2+ channels in the membrane of the endoplasmic reticulum, allowing Ca2+ to be released into the cytoplasm, where it can bind to Ca2+-dependent fluorescent dyes, such as Fluo-4, that are added to the cells71.&#160;This process occurs within seconds and can increase the concentration of Ca2+ 100-fold, leading to a drastic change in the amount of calcium-bound dye and a robust fluorescence signal.
In 2018, the Dockendorff group disclosed a medium-throughput Ca2+ mobilization assay that could be used to identify antagonists of the G&#945;q pathway of PAR172. The assay used&#160;EA.hy92673, a hybrid human endothelial cell line, which can be used for multiple passages without a noticeable change in PAR1 expression, and is established for in vitro measurements of cytoprotective effects.&#160;
The original protocol used EA.hy926 cells in 96-well plates and loaded with Fluo-4/AM dye, which was chosen due to its intense fluorescence at 488 nm and high cell permeability. Once the dye was loaded into the cells, lengthy washing steps were performed with an automated 8-channel liquid handler (faster methods of liquid handling, such as a 96-channel washer, were inaccessible). The reproducibility of this assay was superior to that without the careful, automated robotic media changes. Antagonists were then incubated with the cells, PAR1 was activated through the sequential addition of a selective agonist (16 wells at a time), and changes in fluorescence resulting from calcium mobilization and dye binding were measured to determine activity.
While this protocol allows for the measurement of PAR1-mediated calcium mobilization, it is limited by the time required to assay each 96-well plate. Long experiment times are problematic not only because the number of compounds that can be screened each day is limited, but also because dye efflux occurs over time, narrowing the assay window by increasing the basal fluorescence. One contributor to the long experiment time is the use of an 8-channel liquid handler for plate washing, which adds over 30 min to each experiment. The required tips also became difficult to obtain due to supply chain problems. Here an updated protocol for the PAR-mediated calcium mobilization assay that does not require a liquid handler, and therefore can be run in higher throughput, is reported. This protocol should also be suitable for measuring signaling with other GPCRs that lead to intracellular calcium mobilization.&#160;This updated plate reader protocol&#160;is ideal for academic and small industrial labs that do not have the resources for expensive cell imaging instruments but have a need to rapidly screen numerous compounds. For an example of a calcium mobilization assay using a plate imager, see Caers et al.74.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Cell Culture Reagents</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Adherent EA.hy926 cells</td>
			<td>ATCC</td>
			<td>CRL-2922</td>
			<td></td>
		</tr>
		<tr>
			<td>CellStripper cell dissociation reagent</td>
			<td>Corning</td>
			<td>25-056-CI</td>
			<td>Trypsin can optionally be used, but should definitely be avoided with PAR2 assays.</td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Modified Eagle Medium (DMEM) w/phenol red</td>
			<td>Corning</td>
			<td>10-013-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>Avantor</td>
			<td>97068-091</td>
			<td></td>
		</tr>
		<tr>
			<td>Gelatin from porcine skin</td>
			<td>MilliporeSigma</td>
			<td>G2500</td>
			<td>Use to make an aqueous 0.4% (w/v) solution with deionized water. Autoclave before use to sterilize.</td>
		</tr>
		<tr>
			<td>Pen/Strep (100X)</td>
			<td>Corning</td>
			<td>30-002-CI</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate-buffered saline (PBS)</td>
			<td>Corning</td>
			<td>21-040-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypan Blue (0.4% w/v)</td>
			<td>Corning</td>
			<td>25-900-CI</td>
			<td></td>
		</tr>
		<tr>
			<td>Calcium Mobilization Reagents</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES)</td>
			<td>Thermo</td>
			<td>172571000</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine serum albumin (BSA)</td>
			<td>Avantor</td>
			<td>97061-420</td>
			<td></td>
		</tr>
		<tr>
			<td>Calcium chloride dihydrate</td>
			<td>Thermo</td>
			<td>42352-0250</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl sulfoxide</td>
			<td>Thermo</td>
			<td>J66650-AD</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluo-4/AM</td>
			<td>Invitrogen</td>
			<td>F14201</td>
			<td></td>
		</tr>
		<tr>
			<td>Hank&#39;s balanced salt solution (Ca/Mg/phenol-red free)</td>
			<td>Corning</td>
			<td>21-022-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium chloride hexahydrate</td>
			<td>MilliporeSigma</td>
			<td>M2393</td>
			<td></td>
		</tr>
		<tr>
			<td>Pluronic F-127 (Poloxamer 407)</td>
			<td>Spectrum Chemical</td>
			<td>P1166</td>
			<td></td>
		</tr>
		<tr>
			<td>Probenecid</td>
			<td>TCI America</td>
			<td>P1975</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium hydroxide</td>
			<td>VWR International</td>
			<td>BDH9292</td>
			<td></td>
		</tr>
		<tr>
			<td>TFLLRN-NH2 (TFA salt)</td>
			<td></td>
			<td></td>
			<td>Prepared by Trudy Holyst at the Versiti Blood Research Institute</td>
		</tr>
		<tr>
			<td>Materials</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>96-well culture-treated, black-walled, clear bottom assay plate</td>
			<td>Corning</td>
			<td>3603</td>
			<td>with transparent lids</td>
		</tr>
		<tr>
			<td>Centrifuge tube, 15 mL</td>
			<td>Avantor</td>
			<td>89039-664</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge tube, 50 mL</td>
			<td>Avantor</td>
			<td>89039-656</td>
			<td></td>
		</tr>
		<tr>
			<td>Culture flask, T-75</td>
			<td>Corning</td>
			<td>353136</td>
			<td>tissue culture treated</td>
		</tr>
		<tr>
			<td>Disposable reagent reservoir, 50 mL</td>
			<td>Corning</td>
			<td>RES-V-50-S</td>
			<td></td>
		</tr>
		<tr>
			<td>Enspire plate reader</td>
			<td>Perkin Elmer</td>
			<td></td>
			<td>Discontinued</td>
		</tr>
		<tr>
			<td>Microcentrifuge tube, 1.5 mL</td>
			<td>Avantor</td>
			<td>20170-038</td>
			<td></td>
		</tr>
		<tr>
			<td>Pasteur pipette, 9&#34;</td>
			<td>Fisher</td>
			<td>13-678-6B</td>
			<td>must be sterilized</td>
		</tr>
		<tr>
			<td>PCR tube strip with separate flat cap strips</td>
			<td>Avantor</td>
			<td>76318-802</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette tips, 20 &#181;L</td>
			<td>Biotix</td>
			<td>63300042</td>
			<td>sterile, filtered tips</td>
		</tr>
		<tr>
			<td>Pipette tips, 200 &#181;L</td>
			<td>Biotix</td>
			<td>63300044</td>
			<td>sterile, filtered tips</td>
		</tr>
		<tr>
			<td>Pipette tips, 1250 &#181;L</td>
			<td>Biotix</td>
			<td>63300047</td>
			<td>sterile, filtered tips</td>
		</tr>
		<tr>
			<td>Prism</td>
			<td>GraphPad</td>
			<td></td>
			<td>volume 6 used</td>
		</tr>
		<tr>
			<td>Serological pipette, 5 mL</td>
			<td>Tradewinds Direct</td>
			<td>&#160;07-5005</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological pipette, 10 mL</td>
			<td>Tradewinds Direct</td>
			<td>&#160;07-5010</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological pipette, 25 mL</td>
			<td>Tradewinds Direct</td>
			<td>&#160;07-5025</td>
			<td></td>
		</tr>
	</tbody>
</table>

characterizing modulators of protease-activated receptors with a calcium mobilization assay using a plate reader

Changes in calcium concentration in cells are rapidly monitored in a high-throughput fashion with the use of intracellular, fluorescent, calcium-binding dyes and imaging instruments that can measure fluorescent emissions from up to 1,536 wells simultaneously. However, these instruments are much more expensive and can be challenging to maintain relative to widely available plate readers that scan wells individually. Described here is an optimized plate reader assay for use with an endothelial cell line (EA.hy926) to measure the protease-activated receptor (PAR)-driven activation of G&#945;q signaling and subsequent calcium mobilization using the calcium-binding dye Fluo-4. This assay has been used to characterize a range of PAR ligands, including the allosteric PAR1-targeting anti-inflammatory "parmodulin" ligands identified in the Dockendorff lab. This protocol obviates the need for an automated liquid handler and permits the medium-throughput screening of PAR ligands in 96-well plates and should be applicable to the study of other receptors that initiate calcium mobilization.

Author Spotlight: Developing Parmodulins to Target Protease-Activated Receptors for Inflammation Control

Characterizing Modulators of Protease-Activated Receptors with a Calcium Mobilization Assay Using a Plate Reader

Our lab is working to understand how the modulation of protease activated receptors can inhibit inflammation. We have developed a new class of small molecules called parmodulins that modulate the activity of PAR1. The goal is to discover parmodulins with improved properties for potential use as drug candidates, and also to understand their mode of action.In preclinical studies with our collaborators, we've determined that parmodulins may be particularly promising for the treatment of disorders driven by thromboinflammation, including kidney, liver, and cardiovascular disease. Their mode of action may also enable the development of compounds with a better safety profile than prior PAR1 targeting drug candidates. The receptor PAR1 is important for activating platelets, but it's signaling in endothelial cells is also important and relevant in numerous pathologies.Therefore, we wanted to develop a cheap and convenient protocol for testing the activity of parmodulins and cultured endothelial cells. We're here to share an updated protocol measuring calcium mobilization that uses a standard plate reader, and does not require an automated liquid handler. It's suitable for screening PAR1 ligands in endothelial cells, but in theory, it can be used to measure the activity of any compounds affecting calcium mobilization.

The purpose of this assay is generally to produce concentration-response curves (CRCs) for three to four new parmodulins. On each assay plate, an additional CRC for a known compound, such as NRD-21, is often generated that acts as a quality check for the experiment due to its known IC50. To generate CRCs, a plate map such as the one depicted in Table 1 should be planned. If single-point concentration-responses are desired instead, compounds at 10 &#181;M final concentrations (or other preferre...

An improved protocol for a calcium mobilization assay with endothelial cells, used to identify ligands of protease-activated receptors (PARs), has been developed. The new protocol reduces total assay time by 90-120 min and yields reproducible concentration-response curves.

Changes in calcium concentration in cells are rapidly monitored in a high-throughput fashion with the use of intracellular, fluorescent, calcium-binding ...

characterizing-modulators-protease-activated-receptors-with-calcium

Research

JoVE Journal

Biochemistry

234 ビュー.  Function Therapeutics. 私たちの研究室では、プロテアーゼ活性化受容体の調節がどのように炎症を抑制できるかを理解するために取り組んでいます。私たちは、PAR1の活性を調節するパルモジュリンと呼ばれる新しいクラスの小分子を開発しました。目標は、薬剤候補としての可能性を秘めた特性を改善したパルモジュリンを発見し、その作用機序を理解することです...

ビデオ: 著者スポットライト:炎症制御のためのプロテアーゼ活性化受容体を標的とするパルモジュリンの開発

An improved protocol for a calcium mobilization assay with endothelial cells, used to identify ligands of protease-activated receptors (PARs), has been developed. The new protocol reduces total assay time by 90-120 min and yields reproducible concentration-response...

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technique to target microinjection to the developing xenopus kidney

Technique to Target Microinjection to the Developing Xenopus Kidney

Here, we present a protocol to use fate maps and lineage tracers to target injections into individual blastomeres that give rise to the kidney of Xenopus laevis embryos.

Technique to Target Microinjection to the Developing Xenopus Kidney

a new hybrid quantitative evaluation model for axillary junctional hemorrhage in swine

Author Spotlight: Developing a Novel Hemorrhage Model for Junctional Area Bleeding Control

This study presents a hybrid quantitative model for axillary junctional hemorrhage in swine, enhancing pre-hospital hemostatic intervention...

Swine Axillary Artery Injury Model for Testing Pre-Hospital Hemostatic Products

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cell-based drug screening for inhibitors of autophagy related 4b cysteine peptidase

Author Spotlight: A Selective Luciferase-Based Assay for Monitoring ATG4B 27 Activity in Cells 

Here, we describe a detailed protocol for the use of a luciferase-based reporter assay in a semi-automated, high-throughput screening...

High-Throughput Screening Analysis for 4B Cysteine Peptidase Autophagy Inhibitor

use of the protease fluorescent detection kit to determine protease activity

Use of the Protease Fluorescent Detection Kit to Determine Protease Activity

The Protease Fluorescent Detection Kit is designed for the measurement of protease activity using fluorometry. It is also suitable for detection of trace amounts of protease contamination. The method is based on the proteolytic hydroysis of a proprietary formulation of a FITC-labeled casein...

development and application of rapamycin-regulated tyrosine phosphatases

Author Spotlight: Developing Tools to Tune the Activity of Tyrosine Phosphatases

This protocol describes the design, creation, and application of rapamycin-regulated phosphatases. This method provides high specificity and tight temporal control of phosphatase activation in living...

Temporal Regulation of Phosphatase Activity with the Rapamycin-Regulated System

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an acetyl-click chemistry assay to measure histone acetyltransferase 1 acetylation

Author Spotlight: Developing Acetyl-Click Assay for HAT1 Inhibitor Screening

Quick and accurate chemical assays to screen for specific inhibitors are an important tool in the drug development arsenal. Here, we present a scalable acetyl-click chemistry assay to measure the inhibition of HAT1 acetylation...

Development of a Click-Based Assay for Screening HAT1 Enzyme Activity

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nanosensors to detect protease activity in vivo for noninvasive diagnostics

Nanosensors to Detect Protease Activity In Vivo for Noninvasive Diagnostics

Proteases are tightly regulated enzymes involved in fundamental biological processes, and dysregulated protease activity drives progression of complex diseases such as cancer. This method&#39;s goal is to create nanosensors that measure protease activity in vivo by producing a cleavage signal that is detectable from host urine and discriminates...

Nanosensors to Detect Protease Activity In Vivo for Noninvasive Diagnostics

developing drosophila melanogaster models for imaging and optogenetic control of cardiac function

Developing Drosophila melanogaster Models for Imaging and Optogenetic Control of Cardiac Function

The present protocol describes the generation of Drosophila melanogaster expressing eNpHR2.0 or ReaChR opsins in the heart for OCT imaging and optogenetic heart pacing. Detailed instructions for Drosophila OCT imaging and heart beating modulation, including the simulation of restorable heart arrest, bradycardia, and tachycardia in live animals at different developmental stages, are...

Developing Drosophila melanogaster Models for Imaging and Optogenetic Control of Cardiac Function

monitoring activation of the antiviral pattern recognition receptors rig-i and pkr by limited protease digestion and native page

Monitoring Activation of the Antiviral Pattern Recognition Receptors RIG-I And PKR By Limited Protease Digestion and Native PAGE

Innate defenses to virus infections are triggered by pattern recognition receptors (PRRs). The two cytoplasmic PRRs RIG-I and PKR bind to viral signature RNAs, change conformation, oligomerize, and activate antiviral signaling. Methods are described which allow to conveniently monitor the conformational switching and the oligomerization of these cytoplasmic...

engineering chimeric antigen receptor-natural killer cells targeting fungal infections using the non-viral sleeping beauty transposon system

Author Spotlight: Developing Cellular Therapies for Invasive Fungal Infections

We outline a transfection protocol for producing chimeric antigen receptor-natural killer (CAR-NK) cells targeting fungal pathogens using the non-viral Sleeping Beauty transposon system. To assess antigen-specific activation, we co-cultured the engineered cells with Aspergillus fumigatus germ tubes and measured IFN-&#947;...

Sleeping Beauty Approach to Obtain CAR-NK Cells for Targeting Fungal Pathogens

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screening people on standing balance with romberg testing and walking balance with tandem walking

Author Spotlight: Developing Low-Tech Balance Assessment Methods for Broad-Spectrum Healthcare Applications 

This article describes procedures for screening people for standing and walking balance impairments using two normed, rapid, low-tech balance tests.

Implementing Vestibular Disorder Screening Tests

quantifying the modulation of elastase enzyme activity through colorimetric analysis

Author Spotlight: Quantifying Activity of Natural Plant Extracts for Developing Efficient Bioactive Molecules

This protocol describes the development of a colorimetric assay method for determining the ability of compounds to inhibit or activate elastase...

Measuring Elastase Modulation: A Colorimetric Assay for Therapeutic Insights

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rodent inferior vena cava venoplasty balloon model

Author Spotlight: Utilizing Venoplasty Balloon Model in Rodents to Simulate Surgical Interventions for Deep Veins

The protocol presents a survival rodent model to test venoplasty balloon (VB) interventions in non-thrombotic, thrombotic, and post-thrombotic deep...

Rodent Venoplasty Balloon Model for Deep Vein Treatment Studies

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a high-throughput luciferase assay to evaluate proteolysis of the single-turnover protease pcsk9

A High-Throughput Luciferase Assay to Evaluate Proteolysis of the Single-Turnover Protease PCSK9

This protocol presents a method to evaluate the proteolytic activity of an intrinsically low-activity, single turnover protease in a cellular context. Specifically, this method is applied to evaluate the proteolytic activity of PCSK9, a key driver of lipid metabolism whose proteolytic activity is required for its ultimate hypercholesterolemic...

a semi-automated workflow for the cryopreservation of coral sperm to support biobanking and aquaculture

Author Spotlight: Developing Efficient Cryopreservation and Biobanking Technologies for Global Reef Restoration

This protocol describes a semi-automated pathway to improve the efficiency and capacity of processing and cryopreservation of sperm from threatened coral species, aiming to secure genetic diversity and support reef restoration...

Optimizing Coral Sperm Cryopreservation from Threatened Coral Species

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non-invasive compression-induced anterior cruciate ligament (acl) injury and in vivo imaging of protease activity in mice

Author Spotlight: Investigating Early Events and Long-Term Effects of ACL Injuries for Osteoarthritis Progression

Non-invasive ACL injury is a reliable and clinically relevant method for initiating post-traumatic osteoarthritis (PTOA) in mice. This injury method also allows for in vivo quantification of protease activity in the joint at early time points post-injury using protease-activatable near infrared probes and fluorescence reflectance...

Impact of Non-Invasive ACL Injury and Surgery on Protease Activity in Mice

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an approach to constructing multispecies biofilm communities from rhizosphere soil

Author Spotlight: Developing Synthetic Microbial Communities for Generating Second-Generation Biofertilizers

A rapid and standardized procedure for establishing synergistic multispecies biofilm communities from various rhizosphere soils is presented here. It is a unique protocol designed to probe and simulate the complex rhizosphere soil...

Developing Synergistic Multispecies Biofilms from Rhizosphere Soil

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Culturing the Endothelial Cell Line in 96-Well Plates for the Calcium Mobilization Assay

To begin, arrange the required experimental materials on the working platform. Add 100 microliters of sterile 0.4%gelatin solution to the wells of a black walled 96 well clear bottom plate. Incubate the plate at 37 degrees Celsius and 5%carbon dioxide for 30 minutes.Under an inverted microscope, confirm that endothelial cells in a T75 flask are 80 to 100%confluent. Remove the DMEM complete medium from the flask via aspiration. To wash the cells, add 10 milliliters of PBS and gently shake the flask.Replace the PBS with five milliliters of cell dissociation solution. Incubate the flask at 37 degrees Celsius and 5%carbon dioxide for approximately 12 minutes. Tap the flask after six minutes.To help facilitate dissociation. Add five milliliters of the prewarmed DMEM complete medium to the flask, and mix the cell suspension. Using a 10 milliliter serological pipette, transfer the cell suspension into a sterile 50 milliliter tube and centrifuge at 150 G for five minutes.In the meantime, using a pastor pipette connected to a vacuum, aspirate the gelatin solution from the 96 well plate. After centrifugation of the cells, remove the supernatin from the tube without disturbing the pellet. Using a serological pipette, add eight milliliters of fresh DMEM complete medium to the tube, and gently pipette the suspension to break up the cell pellet.Count the cells using trippen blue on a hemocytometer. Add DMEM complete medium to make a density of 600, 000 cells per milliliter suspension. Mix the cell suspension by gently inverting the tube.Add the cell suspension to a 50 milliliter multi-channel pipette reservoir. Every 30 seconds, gently rock the reservoir side to side to mix the suspension and use a multi-channel pipette to add 100 microliters to each well of the 96 well plate coated with gelatin. Replace the transparent plate cover and gently shake the plate by sliding it on the surface of the sterile hood from north to south and east to west.Incubate the plate at 37 degrees Celsius with 5%carbon dioxide for 16 to 24 hours.

Enhanced Plate Reader Assay for Calcium Mobilization in Endothelial Cells

After growing endothelial cells in the 96 well plate, remove it from the incubator and confirm confluency using an inverted microscope. Flick the plate into a sink to remove the complete media, and blot the top of the plate with a paper towel. Add HBSS HEPES assay buffer plus probenecid solution to a 50 milliliter multi-channel pipette solvent reservoir.Using a multi-channel pipette, add 100 microliters of assay buffer to each well and allow the cells to sit for five minutes. Then, flick the plate to remove the assay buffer. Add downloading buffer to a separate 50 milliliter multi-channel pipette solvent reservoir.Using a multi-channel pipette, add 50 microliters of the dye-loading buffer to each well of the assay plate. Incubate the plate at 37 degrees Celsius and 5%carbon dioxide for 45 minutes. After incubation, observe the plate under a fluorescence microscope to confirm the dye uptake.Flick the plate to remove the dye solution. Wash the cells twice with 50 microliters of the HBSS HEPES assay buffer plus probenecid solution in each well. Flick the plate to remove the assay buffer.Add 92 microliters of HBSS HEPES assay buffer to each well, and again, view the cells with a fluorescence microscope to ensure excess dye has been fully removed and that cells remain adherent. Using a multi-channel pipette, add two microliters of the antagonist solutions and vehicle to appropriate wells. After turning on the plate reader, set the temperature to 37 degrees Celsius and incubate the plate for 15 minutes.Measure the background fluorescence in columns one and two, performing five scans per well. Eject the plate from the plate reader, then from an 8-tube PCR strip, quickly add six microliters of agonist solution using a multi-channel pipette to each well in columns one and two. Measure the change in fluorescence as calcium mobilization occurs in the cells.Perform 20 scans of each well. The calcium mobilization assay with endothelial cells demonstrated that positive control wells with no antagonist exhibited a rapid increase in fluorescence. Wells with high antagonist concentrations showed minimal change in fluorescence, similar to the negative control wells with no agonist.