Name: efficient transfection of in vitro transcribed mrna in cultured cells using peptide-poloxamine nanoparticles
Uploaded: 2022-08-17T14:20:00
Description: Watch this Scientific Journal Video about Efficient Transfection of In vitro Transcribed mRNA in Cultured Cells Using Peptide-Poloxamine Nanoparticles at JoVE.com

This work was supported by the National Natural Science Foundation of China (NSFC, Grant No. 82041045 and 82173764), the major project of Study on Pathogenesis and Epidemic Prevention Technology System (2021YFC2302500) by the Ministry of Science and Technology of China, the Chongqing Talents: Exceptional Young Talents Project (CQYC202005027), and the Natural Science Foundation of Chongqing (cstc2021jcyj-msxmX0136). The authors are grateful to Dr. Xiaoyan Ding for measuring the hydrodynamic diameter (nm) and polydispersity index (PDI).

1. In vitro transcription of chemically modified mRNA
NOTE: It is required to use nuclease-free tubes, reagents, glassware, pipette tips, etc., because RNases are ubiquitous in the environment, such as laboratory solutions, instrument surfaces, hair, skin, dust, etc. Clean the bench surfaces and pipettes thoroughly before use, and wear gloves to avoid RNase contamination.
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	<li>Perform linearization of the DNA template.
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		<li>Synthesize the open reading fr...

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	<li>Nature milestones in vaccines. Springer Nature Available from: <a target="_blank" href="https://www.nature.com/collections/hcajdiajij">https://www.nature.com/collections/hcajdiajij</a> (2020)</li><li>Barbier, A. J., Jiang, A. Y., Zhang, P., Wooster, R., Anderson, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+clinical+progress+of+mRNA+vaccines+and+immunotherapies.">The clinical progress of mRNA vaccines and immunotherapies.</a> Nature Biotechnology. 40 (6), 840-854 (2022).</li><li>Mulligan, M. 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V., 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=Database+for+mRNA+half-life+of+19+977+genes+obtained+by+DNA+microarray+analysis+of+pluripotent+and+differentiating+mouse+embryonic+stem+cells.">Database for mRNA half-life of 19 977 genes obtained by DNA microarray analysis of pluripotent and differentiating mouse embryonic stem cells.</a> DNA Research. 16 (1), 45-58 (2009).</li><li>Houseley, J., Tollervey, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+many+pathways+of+RNA+degradation.">The many pathways of RNA degradation.</a> Cell. 136 (4), 763-776 (2009).</li><li>Kowalski, P. S., Rudra, A., Miao, L., Anderson, D. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tools+for+translation:+Non-viral+materials+for+therapeutic+mRNA+delivery.">Tools for translation: Non-viral materials for therapeutic mRNA delivery.</a> Nature Reviews Materials. 2, 17056 (2017).</li><li>Deering, R. P., Kommareddy, S., Ulmer, J. B., Brito, L. A., Geall, A. 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The protocol described here not only allows the cost-effective and rapid production of IVT mRNA vaccine formulations with defined properties, but it also offers the possibility to customize the PP-sNp formulation according to specific therapeutic purposes, such as gene therapy. In order to ensure the successful generation of IVT mRNA/PP-sNp, it is suggested to pay extra attention to some critical steps. When working with mRNA, always remember that RNase-free conditions should be maintained throughout the process because ...

Vaccination has been heralded as one of the most efficient medical interventions for reducing the morbidity and mortality caused by infectious diseases1. The importance of vaccines has been demonstrated since the outbreak of coronavirus disease 2019 (COVID-19). As opposed to the traditional concept of injecting inactivated or live-attenuated pathogens, state-of-the-art vaccine approaches, such as nucleic acid-based vaccines, concentrate on preserving the immune-stimulatory properties of the target pathogens while avoiding the potential safety issues associated with the conventional whole-microbial virus- or in bacteria-based vaccines. Both DNA- and RNA (i.e., in vitro transcribed messenger RNA, IVT mRNA)-based vaccines exhibit prophylactic to therapeutic potential against a variety of diseases, including infectious diseases and cancers2,3. In principle, the potential of nucleic acid-based vaccines relates to their production, efficacy, and safety4. These vaccines can be manufactured in a cell-free manner to allow cost-effective, scalable, and rapid production.
A single nucleic acid-based vaccine can encode multiple antigens, enabling the target of numerous viral variants or bacteria with a reduced number of inoculations and strengthening the immune response against resilient pathogens5,6.&#160;Besides, nucleic acid-based vaccines could mimic the natural invasion process of virus or bacterial infection, bringing both B cell- and T cell-mediated immune responses. Unlike some virus- or in DNA-based vaccines, IVT mRNA-based vaccines offer a huge advantage in terms of safety. They can rapidly express the desired antigen in the cytosol and are not integrated into the host genome, obviating concerns about insertional mutagenesis7. IVT-mRNA is automatically degraded after successful translation, so its protein expression kinetics can be easily controlled8,9. Catalyzed by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, efforts from companies/institutions worldwide have enabled the release to the market of many types of vaccines. IVT mRNA-based vaccine technology shows great potential and, for the first time, has demonstrated its previously anticipated success, owing to its rapid design and flexible capacity to adapt to any target antigens within several months. The success of IVT mRNA vaccines against COVID-19 in clinical applications not only opened up a new era of IVT mRNA vaccine research and development but also accumulated valuable experience for the rapid development of effective vaccines for dealing with outbreaks of infectious diseases10,11.
Despite the promising potential of IVT mRNA vaccines, the efficient intracellular delivery of IVT mRNA to the site of action (i.e., cytoplasm) continues to pose a major hurdle12, especially for those administered via the airways4. IVT mRNA is inherently an unstable molecule with an extremely short half-life (~7 h)13, which renders IVT mRNA highly prone to degradation by the ubiquitous RNase14. The lymphocytes of the innate immune system tend to engulf the recognized IVT mRNA in cases of in vivo application. Moreover, the high negative charge density and large molecular weight (1 x 104-1 x 106 Da) of IVT mRNA impair its effective permeation across the anionic lipid bilayer of cellular membranes15. Therefore, a delivery system with certain bio-functional materials is required to inhibit the degradation of the IVT mRNA molecules and facilitate cellular uptake16.
Apart from a few exceptional cases in which naked IVT mRNA was directly utilized for in vivo investigations, various delivery systems are used to carry IVT mRNA to the therapeutic site of action17,18. Previous studies have revealed that only a few IVT mRNAs are detected in cytosol without the assistance of a delivery system19. Numerous strategies have been developed to improve RNA delivery with continuous efforts in the field, ranging from protamine condensation to lipid encapsulation20. Lipid nanoparticles (LNPs) are the most clinically advanced among the mRNA delivery vehicles, as proved by the fact that all the approved mRNA COVID-19 vaccines for clinical use employ LNP-based delivery systems21. However, LNPs cannot mediate effective mRNA transfection when the formulations are delivered via the respiratory route22, which remarkably limits the application of these formulations in inducing mucosal immune responses or addressing pulmonary-related diseases such as cystic fibrosis or &#945;1-antitrypsin deficiency. Therefore, developing a novel delivery system to facilitate the efficient delivery and transfection of IVT mRNA in airway-related cells is required to solve this unmet need.
It has been confirmed that the peptide-poloxamine self-assembled nanoparticle (PP-sNp) delivery system can mediate the efficient transfection of nucleic acids in the respiratory tract of mice23. The PP-sNp adopts a multifunctional modular design approach, which can integrate different functional modules into the nanoparticles for rapid screening and optimization23. The synthetic peptides and electrically neutral amphiphilic block copolymers (poloxamine) within the PP-sNp can spontaneously interact with IVT mRNA to generate uniformly distributed nanoparticles with a compact structure and smooth surface23. PP-sNp&#160;can improve the gene transfection effect of IVT mRNA molecules in cultured cells and the respiratory tract of mice23. The present study describes a protocol for generating PP-sNp&#160;containing IVT mRNA that encodes Metridia luciferase (MetLuc-mRNA) (Figure 1). Controlled and rapid mixing via a microfluidic mixing device, which employs the staggered herringbone mixing design, is utilized in this protocol. The procedure is easy to execute and allows the generation of PP-sNp&#160;with more uniform sizes. The general goal of PP-sNp production using the microfluidic mixer is to create PP-sNp&#160;for mRNA complexation in a well-controlled manner, thus allowing efficient and reproducible cell transfection in vitro. The present protocol describes the preparation, assembly, and characterization of PP-sNp&#160;containing MetLuc-mRNA.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>BamHI</td>
			<td>Takara</td>
			<td>1010</td>
			<td></td>
		</tr>
		<tr>
			<td>cap 1 capping system</td>
			<td>Jinan</td>
			<td>M082</td>
			<td></td>
		</tr>
		<tr>
			<td>Dendritic cell-line</td>
			<td>Sigma</td>
			<td>SCC142</td>
			<td></td>
		</tr>
		<tr>
			<td>DNA sequence</td>
			<td>Genescript</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Human bronchial epithelial cells</td>
			<td>Sigma</td>
			<td>SCC150</td>
			<td></td>
		</tr>
		<tr>
			<td>KpnI</td>
			<td>Takara</td>
			<td>1068</td>
			<td></td>
		</tr>
		<tr>
			<td>LP</td>
			<td>Beyotime</td>
			<td>C0533</td>
			<td></td>
		</tr>
		<tr>
			<td>Lithium chloride</td>
			<td>APEXBio</td>
			<td>B6083</td>
			<td></td>
		</tr>
		<tr>
			<td>Malvern Zetasizer Nano ZS90</td>
			<td>Malvern</td>
			<td>NB007605</td>
			<td></td>
		</tr>
		<tr>
			<td>Microfluidic chip</td>
			<td>ZHONGXINQIHENG</td>
			<td>Standard PDMS chip</td>
			<td></td>
		</tr>
		<tr>
			<td>Microplate readers</td>
			<td>ThermoFisher</td>
			<td>Varioskan lux</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoDrop One</td>
			<td>ThermoFisher</td>
			<td>ND-ONE-W (A30221)</td>
			<td></td>
		</tr>
		<tr>
			<td>Nuclease-free water</td>
			<td>ThermoFisher</td>
			<td>AM9932</td>
			<td></td>
		</tr>
		<tr>
			<td>OptiMEM</td>
			<td>Gibco</td>
			<td>31985070</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-streptomycin</td>
			<td>Gibco</td>
			<td>15140122</td>
			<td></td>
		</tr>
		<tr>
			<td>Pseudouridine</td>
			<td>APE&#215;Bio</td>
			<td>B7972</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAprep Spin Miniprep Kit</td>
			<td>Qiagen</td>
			<td>27106</td>
			<td></td>
		</tr>
		<tr>
			<td>Quanti-Luc</td>
			<td>InvivoGen</td>
			<td>Rep-qlc2</td>
			<td></td>
		</tr>
		<tr>
			<td>RiboRuler High Range RNA Ladder</td>
			<td>ThermoFisher</td>
			<td>SM1821</td>
			<td></td>
		</tr>
		<tr>
			<td>RNase-free conical tube</td>
			<td>Biosharp</td>
			<td>BS-100-M</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI Medium 1640</td>
			<td>ThermoFisher</td>
			<td>C11875500BT</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe pump</td>
			<td>Chemyx</td>
			<td>Fusion 101</td>
			<td></td>
		</tr>
		<tr>
			<td>T7 transcription Kit</td>
			<td>Jinan</td>
			<td>E131</td>
			<td></td>
		</tr>
	</tbody>
</table>

efficient transfection of in vitro transcribed mrna in cultured cells using peptide-poloxamine nanoparticles

In vitro transcribed messenger RNA (mRNA) vaccines have displayed enormous potential in fighting against the coronavirus disease 2019 (COVID-19) pandemic. Efficient and safe delivery systems must be included in the mRNA vaccines due to the fragile properties of mRNA. A self-assembled peptide-poloxamine nanoparticle (PP-sNp) gene delivery system is specifically designed for the pulmonary delivery of nucleic acids and displays promising capabilities in mediating successful mRNA transfection. Here, an improved method for preparing PP-sNp is described to elaborate on how the PP-sNp&#160;encapsulates Metridia luciferase (MetLuc) mRNA and successfully transfects cultured cells. MetLuc-mRNA is obtained by an in vitro transcription process from a linear DNA template. A PP-sNp&#160;is produced by mixing synthetic peptide/poloxamine with mRNA solution using a microfluidic mixer, allowing for the self-assembly of PP-sNp. The charge of PP-sNp&#160;is subsequently evaluated by measuring the zeta potential. Meanwhile, the polydispersity and hydrodynamic size of PP-sNp&#160;nanoparticles are measured using dynamic light scattering. The mRNA/PP-sNp nanoparticles are transfected into cultured cells, and supernatants from the cell culture are assayed for luciferase activity. The representative results demonstrate their capacity for in vitro transfection. This protocol may shed light on developing next-generation mRNA vaccine delivery systems.

The recombinant plasmid was digested to produce the linearized DNA template (Figure 2A). Using the protocol described, The T7 in vitro transcription kit can produce up to 80-120 &#181;g of uncapped MetLuc-mRNA per 20 &#181;L reaction and 50-60 &#181;g of capped MetLuc-mRNA per 100 &#181;L reaction. When analyzed with electrophoresis, intact MetLuc-mRNA with high quality should show a single and clear band, as displayed in Figure 2B. Contaminants introdu...

Watch this Scientific Journal Video about Efficient Transfection of In vitro Transcribed mRNA in Cultured Cells Using Peptide-Poloxamine Nanoparticles at JoVE.com

Efficient Transfection of In vitro Transcribed mRNA in Cultured Cells Using Peptide-Poloxamine Nanoparticles

A self-assembled peptide-poloxamine nanoparticle (PP-sNp) is developed using a microfluidic mixing device to encapsulate and deliver in vitro transcribed messenger RNA. The described mRNA/PP-sNp could efficiently transfect cultured cells in vitro.

Efficient Transfection of In vitro Transcribed mRNA in Cultured Cells Using Peptide-Poloxamine Nanoparticles

In vitro transcribed messenger RNA (mRNA) vaccines have displayed enormous potential in fighting against the coronavirus disease 2019 (COVID-19) pandemic. ...

Peptide-poloxamine nanoparticles is one of the potential pulmonary mRNA delivery systems. Our protocol makes the peptide-poloxamine nanoparticles with higher productivity and efficiency, which facilitates the development of the mucosal mRNA vaccine. The materials required by the technique are low-cost, and the protocol can be completed in a short time.The peptide-poloxamine nanoparticles have the ability to mediate efficient mRNA transfection. Peptide-poloxamine nanoparticles exhibited successful mRNA transfection in human bronchial epithelial cells, which implicates additional applications for mucosal COVID-19 vaccines, treatment of lung cancers, and cystic fibrosis gene therapy. I expect the individual to have some basic knowledge in a related field and with the protocol and a lot of the techniques as well, before he or she starts performing the experiments.After synthesizing the open reading frame of Metridia luciferase and cloning it into the pUC57 vector, prepare a linearized DNA template using BamHI and KpnI at 37 degrees Celsius for one hour. Prepare a reaction of 20-microliters volume for mRNA synthesis using a T7 transcription kit and pseudouridine as described in the manuscript. Mix the components thoroughly and incubate at 37 degrees Celsius for three hours.Then, remove the secondary structure of 50 micrograms of uncapped IVT mRNA by heating it at 65 degrees Celsius for 10 minutes. Use the Cap 1 capping system for the IVT mRNA capping, and prepare Cap 1 by modifying the 7-methylguanosine cap structure using S-adenosylmethionine and 2'O-methyltransferases at 37 degrees Celsius for 30 to 60 minutes. Measure the concentration of capped IVT mRNA with a UV-visible spectrophotometer.Using an RNA marker, analyze the molecular size of capped IVT mRNA in a 1%formaldehyde denaturing agarose gel containing 18%formaldehyde. Prepare 10 milligrams per milliliter stock solution of poloxamine 704 by solubilizing the T704 in nuclease-free water. Prepare 2 milligrams per milliliter stock solution of the peptide by solubilizing the peptide in nuclease-free water.Store the prepared solution at 4 degrees Celsius. Thaw the IVT mRNA on ice. Before opening the tube, centrifuge the tube at 300 times G for three seconds at room temperature, and dilute the IVT mRNA solution with nuclease-free water.Prepare T704 and synthetic peptide mix solution by diluting T704 solution to eight micrograms per microliter concentration, and synthetic peptide solution to 0.555 micrograms per microliter concentration, with nuclease-free water, respectively. Incubate the mixed solution for 15 minutes at room temperature before further use. Draw the IVT mRNA solution into a one-milliliter syringe, avoiding air gaps or bubbles in the syringe tip.Load the syringe into one side of the cartridge next to the rotating block. Then, fill a one-milliliter syringe with T704 and synthetic peptide mix solution, and remove any bubbles or air gaps at the syringe tip. Place the syringe into the other inlet of the pump, and set the pump with a total flow rate of 4 to 10 milliliters per minute.Place a ten-milliliter RNase-free conical tube to collect the mixed IVT mRNA/PP-sNp solution at the end of the flow path of the mixing device. Run the pump to start the mixing, ensuring the parameters are input correctly. After running the pump for six seconds, collect the IVT mRNA/PP-sNp sample from the conical tube.Plate human bronchial epithelial cells and a dendritic cell line in 96-well plates 24 hours before transfection. Grow the cells in a culture medium supplemented with 10%heat-inactivated fetal bovine serum and 1%penicillin streptomycin. After removing the growth medium, wash the plated cells with 0.2 milliliters per well PBS.Add 170 microliters of serum-free culture medium to each well containing the plated cell cultures. Then, add 30 microliters of IVT mRNA/PP-sNp formulation containing 0.4 micrograms of Metridia luciferase mRNA drop wise into each well. Incubate the cells with the IVT mRNA/PP-sNp formulation in a humidified 5%carbon dioxide-enriched atmosphere at 37 degrees Celsius for four hours.Aspirate the transfection medium and add 0.2 milliliters of fresh culture medium supplemented with 10%heat-inactivated fetal bovine serum and 1%penicillin streptomycin. Incubate the transfected cells for 24 hours as demonstrated earlier and collect the supernatants to be detected from each well. Prepare a fresh assay solution by adding PBS to the coelenterazine substrate.Mix the solution thoroughly by vortexing for 10 seconds. Add 50 microliters of the collected supernatant to a 96-well plate. Set up the microplate reader with a reading time of 1, 000 milliseconds and add 30 microliters of coelenterazine solution to each well manually or by automated injection.Immediately after adding the coelenterazine solution to the supernatant, click on Start to measure the luminescence signal. The recombinant plasmid was isolated and digested to produce the linearized DNA template. The in vitro transcription produced upcapped and capped MetLuc mRNA.Cells transfected with Metridia luciferase mRNA/PP-sNp displayed significantly higher expression of luciferase as compared to those transfected with commercially-available lipid-based transfection reagent, naked Metridia luciferase mRNA, PBS, or T7044 synthetic peptides, mixed solution in human bronchial epithelial cells, 16 HBE, and dendritic cell line DC2.4 Metridia luciferase mRNA/PP-sNp showed higher luciferase expression than LP.suggesting that the PP-sNp delivery system is important for protecting the MetLuc mRNA against degradation and for promoting the transfection efficiency of the exogenous Metridia luciferase mRNA. Please ensure that the synthetic structure of uncapped Met-mRNA is successfully removed. Calculate and download the Met-mRNA T704 and peptide compound carefully to prepare and compact the poloxamine nanoparticles.Transmission electron microscopy can be performed to observe the morphology of peptide-poloxamine nanoparticles. This technique helps researchers to develop mucosal mRNA vaccines and enable high-throughput screening of gene therapy formulations for every related cells.

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Research

JoVE Journal

Immunology and Infection

Genotypic Inference of HIV-1 Tropism Using Population-based Sequencing of V3

Background: Prior to receiving a drug from CCR5-antagonist class in HIV therapy, a patient must undergo an HIV tropism test to confirm that his or her viral population uses the CCR5 coreceptor for cellular entry, and not an alternative coreceptor. One approach to tropism testing is to examine the sequence of the V3 region of the HIV envelope, which interacts with the coreceptor.
Methods: Viral RNA is extracted from blood plasma. The V3 region is amplified in triplicate with nested reverse transcriptase-PCR. The amplifications are then sequenced and analyzed using the software, RE_Call. Sequences are then submitted to a bioinformatic algorithm such as geno2pheno to infer viral tropism from the V3 region. Sequences are inferred to be non-R5 if their geno2pheno false positive rate falls below 5.75%. If any one of the three sequences from a sample is inferred to be non-R5, the patient is unlikely to respond to a CCR5-antagonist.

HIV tropism can be inferred from the V3 region of the viral envelope. V3 is PCR amplified in triplicate using nested RT-PCR, sequenced, and interpreted using bioinformatic software. Samples with with 1 or more sequence(s) with low g2P scores are classified as non-R5 virus.

Background: Prior to receiving a drug from CCR5-antagonist class in HIV therapy, a patient must undergo an HIV tropism test to confirm that his or her ...

Seven Steps to Stellate Cells

Hepatic stellate cells are liver-resident cells of star-like morphology and are located in the space of Disse between liver sinusoidal endothelial cells and hepatocytes1,2. Stellate cells are derived from bone marrow precursors and store up to 80% of the total body vitamin A1, 2. Upon activation, stellate cells differentiate into myofibroblasts to produce extracellular matrix, thus contributing to liver fibrosis3. Based on their ability to contract, myofibroblastic stellate cells can regulate the vascular tone associated with portal hypertension4. Recently, we demonstrated that hepatic stellate cells are potent antigen presenting cells and can activate NKT cells as well as conventional T lymphocytes5. 

 Here we present a method for the efficient preparation of hepatic stellate cells from mouse liver. Due to their perisinusoidal localization, the isolation of hepatic stellate cells is a multi-step process. In order to render stellate cells accessible to isolation from the space of Disse, mouse livers are perfused in situ with the digestive enzymes Pronase E and Collagenase P. Following perfusion, the liver tissue is subjected to additional enzymatic treatment with Pronase E and Collagenase P in vitro. Subsequently, the method takes advantage of the massive amount of vitamin A-storing lipid droplets in hepatic stellate cells. This feature allows the separation of stellate cells from other hepatic cell types by centrifugation on an 8% Nycodenz gradient. The protocol described here yields a highly pure and homogenous population of stellate cells. Purity of preparations can be assessed by staining for the marker molecule glial fibrillary acidic protein (GFAP), prior to analysis by fluorescence microscopy or flow cytometry. Further, light microscopy reveals the unique appearance of star-shaped hepatic stellate cells that harbor high amounts of lipid droplets. 


 Taken together, we present a detailed protocol for the efficient isolation of hepatic stellate cells, including representative images of their morphological appearance and GFAP expression that help to define the stellate cell entity.

Here we describe a method for the isolation of hepatic stellate cells from mouse liver. For stellate cell purification, mouse livers are digested in situ and in vitro by pronase-collagenase treatment prior to density gradient centrifugation. This technique yields highly pure hepatic stellate cells.

Hepatic stellate cells are liver-resident  cells of star-like morphology and are located in the space of Disse between  liver sinusoidal endothelial cells ...

Optimized Protocol for Efficient Transfection of Dendritic Cells without Cell Maturation

Dendritic cells (DCs) can be considered sentinels of the immune system which play a critical role in its initiation and response to infection1. Detection of pathogenic antigen by na&iuml;ve DCs is through pattern recognition receptors (PRRs) which are able to recognize specific conserved structures referred to as pathogen-associated molecular patterns (PAMPS). Detection of PAMPs by DCs triggers an intracellular signaling cascade resulting in their activation and transformation to mature DCs. This process is typically characterized by production of type 1 interferon along with other proinflammatory cytokines, upregulation of cell surface markers such as MHCII and CD86 and migration of the mature DC to draining lymph nodes, where interaction with T cells initiates the adaptive immune response2,3. Thus, DCs link the innate and adaptive immune systems. 
The ability to dissect the molecular networks underlying DC response to various pathogens is crucial to a better understanding of the regulation of these signaling pathways and their induced genes. It should also help facilitate the development of DC-based vaccines against infectious diseases and tumors. However, this line of research has been severely impeded by the difficulty of transfecting primary DCs4.
Virus transduction methods, such as the lentiviral system, are typically used, but carry many limitations such as complexity and bio-hazardous risk (with the associated costs)5,6,7,8. Additionally, the delivery of viral gene products increases the immunogenicity of those transduced DCs9,10,11,12. Electroporation has been used with mixed results13,14,15, but we are the first to report the use of a high-throughput transfection protocol and conclusively demonstrate its utility.
In this report we summarize an optimized commercial protocol for high-throughput transfection of human primary DCs, with limited cell toxicity and an absence of DC maturation16. Transfection efficiency (of GFP plasmid) and cell viability were more than 50% and 70% respectively. FACS analysis established the absence of increase in expression of the maturation markers CD86 and MHCII in transfected cells, while qRT-PCR demonstrated no upregulation of IFN&beta;. Using this electroporation protocol, we provide evidence for successful transfection of DCs with siRNA and effective knock down of targeted gene RIG-I, a key viral recognition receptor16,17, at both the mRNA and protein levels.

We present our optimized high-throughput nucleofection protocol as an efficient way of transfecting primary human monocyte-derived dendritic cells with either plasmid DNA or siRNA without causing cell maturation. We further provide evidence for successful siRNA silencing of targeted gene RIG-I at both the mRNA and protein levels.

Dendritic cells (DCs) can be considered sentinels of the immune system which play a critical role in its initiation and response to infection1. Detection ...

Quantitative In vitro Assay to Measure Neutrophil Adhesion to Activated Primary Human Microvascular Endothelial Cells under Static Conditions

The vascular endothelium plays an integral part in the inflammatory response. During the acute phase of inflammation, endothelial cells (ECs) are activated by host mediators or directly by conserved microbial components or host-derived danger molecules. Activated ECs express cytokines, chemokines and adhesion molecules that mobilize, activate and retain leukocytes at the site of infection or injury. Neutrophils are the first leukocytes to arrive, and adhere to the endothelium through a variety of adhesion molecules present on the surfaces of both cells. The main functions of neutrophils are to directly eliminate microbial threats, promote the recruitment of other leukocytes through the release of additional factors, and initiate wound repair. Therefore, their recruitment and attachment to the endothelium is a critical step in the initiation of the inflammatory response. In this report, we describe an in vitro neutrophil adhesion assay using calcein AM-labeled primary human neutrophils to quantitate the extent of microvascular endothelial cell activation under static conditions. This method has the additional advantage that the same samples quantitated by fluorescence spectrophotometry can also be visualized directly using fluorescence microscopy for a more qualitative assessment of neutrophil binding.

Quantitative In vitro Assay to Measure Neutrophil Adhesion to Activated Primary Human Microvascular Endothelial Cells under Static Conditions

Neutrophil adherence to the activated endothelium at sites of infection is an integral component of the host's inflammatory response. Described in this report is a neutrophil binding assay that allows for the in vitro quantitation of primary human neutrophil binding to endothelial cells activated by inflammatory mediators under static conditions.

The vascular  endothelium plays an integral part in the inflammatory response. During the  acute phase of inflammation, endothelial cells (ECs) are ...

Using Fluorescent Proteins to Visualize and Quantitate Chlamydia Vacuole Growth Dynamics in Living Cells

The obligate intracellular bacterium Chlamydia elicits a great burden on global public health. C.&#160;trachomatis is the leading bacterial cause of sexually transmitted infection and also the primary cause of preventable blindness in the world. An essential determinant for successful infection of host cells by Chlamydia is the bacterium's ability to manipulate host cell signaling from within a novel, vacuolar compartment called the inclusion. From within the inclusion, Chlamydia acquire nutrients required for their 2-3 day developmental growth, and they additionally secrete a panel of effector proteins onto the cytosolic face of the vacuole membrane and into the host cytosol. Gaps in our understanding of Chlamydia biology, however, present significant challenges for visualizing and analyzing this intracellular compartment. Recently, a reverse-imaging strategy for visualizing the inclusion using GFP expressing host cells was described. This approach rationally exploits the intrinsic impermeability of the inclusion membrane to large molecules such as GFP. In this work, we describe how GFP- or mCherry-expressing host cells are generated for subsequent visualization of chlamydial inclusions. Furthermore, this method is shown to effectively substitute for costly antibody-based enumeration methods, can be used in tandem with other fluorescent labels, such as GFP-expressing Chlamydia, and can be exploited to derive key quantitative data about inclusion membrane growth from a range of Chlamydia species and strains.

Using Fluorescent Proteins to Visualize and Quantitate Chlamydia Vacuole Growth Dynamics in Living Cells

A live cell fluorescent protein based method for illuminating cellular vacuoles (inclusions) containing Chlamydia is described. This strategy enables rapid, automated determination of Chlamydia infectivity in samples and can be used to quantitatively investigate inclusion growth dynamics.

The obligate intracellular bacterium Chlamydia elicits a great burden on global public health. C.&#160;trachomatis is the leading bacterial cause of ...

Killer Artificial Antigen Presenting Cells (KaAPC) for Efficient In Vitro Depletion of Human Antigen-specific T Cells

Current treatment of T cell mediated autoimmune diseases relies mostly on strategies of global immunosuppression, which, in the long term, is accompanied by adverse side effects such as a reduced ability to control infections or malignancies. Therefore, new approaches need to be developed that target only the disease mediating cells and leave the remaining immune system intact. Over the past decade a variety of cell based immunotherapy strategies to modulate T cell mediated immune responses have been developed. Most of these approaches rely on tolerance-inducing antigen presenting cells (APC). However, in addition to being technically difficult and cumbersome, such cell-based approaches are highly sensitive to cytotoxic T cell responses, which limits their therapeutic capacity. Here we present a protocol for the generation of non-cellular killer artificial antigen presenting cells (KaAPC), which allows for the depletion of pathologic T cells while leaving the remaining immune system untouched and functional. KaAPC is an alternative solution to cellular immunotherapy which has potential for treating autoimmune diseases and allograft rejections by regulating undesirable T cell responses in an antigen specific fashion.

Killer Artificial Antigen Presenting Cells KaAPC for Efficient In Vitro Depletion of Human Antigen-specific T Cells

Guidelines are presented for the generation of killer artificial antigen presenting cells, KaAPC, an efficient tool for in vitro depletion of human antigen-specific T cells and an alternative solution to cellular immunotherapy for the treatment of T cell-mediated autoimmune diseases in an antigen-specific fashion without compromising the remaining immune system.

Current treatment of T cell mediated autoimmune diseases relies mostly on strategies of global immunosuppression, which, in the long term, is accompanied ...

Highly Efficient Transfection of Human THP-1 Macrophages by Nucleofection

Macrophages, as key players of the innate immune response, are at the focus of research dealing with tissue homeostasis or various pathologies. Transfection with siRNA and plasmid DNA is an efficient tool for studying their function, but transfection of macrophages is not a trivial matter. Although many different approaches for transfection of eukaryotic cells are available, only few allow reliable and efficient transfection of macrophages, but reduced cell vitality and severely altered cell behavior like diminished capability for differentiation or polarization are frequently observed. Therefore a transfection protocol is required that is capable of transferring siRNA and plasmid DNA into macrophages without causing serious side-effects thus allowing the investigation of the effect of the siRNA or plasmid in the context of normal cell behavior. The protocol presented here provides a method for reliably and efficiently transfecting human THP-1 macrophages and monocytes with high cell vitality, high transfection efficiency, and minimal effects on cell behavior. This approach is based on Nucleofection and the protocol has been optimized to maintain maximum capability for cell activation after transfection. The protocol is adequate for adherent cells after detachment as well as cells in suspension, and can be used for small to medium sample numbers. Thus, the method presented is useful for investigating gene regulatory effects during macrophage differentiation and polarization. Apart from presenting results characterizing macrophages transfected according to this protocol in comparison to an alternative chemical method, the impact of cell culture medium selection after transfection on cell behavior is also discussed. The presented data indicate the importance of validating the selection for different experimental settings.

This protocol presents an efficient and reliable method to transfect human THP-1 macrophages with siRNA or plasmid DNA by electroporation with high transfection efficiency while maintaining high cell vitality and full macrophage capacity for differentiation and polarization.

Macrophages, as key players of the innate immune response, are at the focus of research dealing with tissue homeostasis or various pathologies. ...

Derivation of T Cells In Vitro from Mouse Embryonic Stem Cells

The OP9/OP9-DL1 co-culture system has become a well-established method for deriving differentiated blood cell types from embryonic and hematopoietic progenitors of both mouse and human origin. It is now used to address a growing variety of complex genetic, cellular and molecular questions related to hematopoiesis, and is at the cutting edge of efforts to translate these basic findings to therapeutic applications. The procedures are straightforward and routinely yield robust results. However, achieving successful hematopoietic differentiation in vitro requires special attention to the details of reagent and cell culture maintenance. Furthermore, the protocol features technique sensitive steps that, while not difficult, take care and practice to master. Here we focus on the procedures for differentiation of T lymphocytes from mouse embryonic stem cells (mESC). We provide a detailed protocol with discussions of the critical steps and parameters that enable reproducibly robust cellular differentiation in vitro. It is in the interest of the field to consider wider adoption of this technology, as it has the potential to reduce animal use, lower the cost and shorten the timelines of both basic and translational experimentation.

Derivation of T Cells In Vitro from Mouse Embryonic Stem Cells

Mouse embryonic stem cells can be differentiated to T cells in vitro using the OP9-DL1 co-culture system. Success in this procedure requires careful attention to reagent/cell maintenance, and key technique sensitive steps. Here we discuss these critical parameters and provide a detailed protocol to encourage adoption of this technology.

The OP9/OP9-DL1 co-culture system has become a well-established method for deriving differentiated blood cell types from embryonic and hematopoietic ...

Small RNA Transfection in Primary Human Th17 Cells by Next Generation Electroporation

CD4+ T cells can differentiate into several subsets of effector T helper cells depending on the surrounding cytokine milieu. Th17 cells can be generated from na&#239;ve CD4+ T cells in vitro by activating them in the presence of the polarizing cytokines IL-1&#946;, IL-6, IL-23, and TGF&#946;. Th17 cells orchestrate immunity against extracellular bacteria and fungi, but their aberrant activity has also been associated with several autoimmune and inflammatory diseases. Th17 cells are identified by the chemokine receptor CCR6 and defined by their master transcription factor, ROR&#947;t, and characteristic effector cytokine, IL-17A. Optimized culture conditions for Th17 cell differentiation facilitate mechanistic studies of human T cell biology in a controlled environment. They also provide a setting for studying the importance of specific genes and gene expression programs through RNA interference or the introduction of microRNA (miRNA) mimics or inhibitors. This protocol provides an easy to use, reproducible, and highly efficient method for transient transfection of differentiating primary human Th17 cells with small RNAs using a next generation electroporation device.

Next generation electroporation is an efficient method for transfecting human Th17 cells with small RNAs to alter gene expression and cell behavior.

CD4+ T cells can differentiate into several subsets of effector T helper cells depending on the surrounding cytokine milieu. Th17 cells can be generated ...

In Vitro Transcribed RNA-based Luciferase Reporter Assay to Study Translation Regulation in Poxvirus-infected Cells

Every poxvirus mRNA transcribed after viral DNA replication has an evolutionarily conserved, non-templated 5&#39;-poly(A) leader in the 5&#39;-UTR. To dissect the role of 5&#39;-poly(A) leader in mRNA translation during poxvirus infection we developed an in vitro transcribed RNA-based luciferase reporter assay. This reporter assay comprises of four core steps: (1) PCR to amplify the DNA template for in vitro transcription; (2) in vitro transcription to generate mRNA using T7 RNA polymerase; (3) Transfection to introduce in vitro transcribed mRNA into cells; (4) Detection of luciferase activity as the indicator of translation. The RNA-based luciferase reporter assay described here circumvents issues of plasmid replication in poxvirus-infected cells and cryptic transcription from the plasmid. This protocol can be used to determine translation regulation by cis-elements in an mRNA including 5&#39;-UTR and 3&#39;-UTR in systems other than poxvirus-infected cells. Moreover, different modes of translation initiation like cap-dependent, cap-independent, re-initiation, and internal initiation can be investigated using this method.

We present a protocol to study mRNA translation regulation in poxvirus-infected cells using in vitro Transcribed RNA-based luciferase reporter assay. The assay can be used for studying translation regulation by cis-elements of an mRNA, including 5&#8217;-untranslated region (UTR) and 3&#8217;-UTR. Different translation initiation modes can also be examined using this method.

Every poxvirus mRNA transcribed after viral DNA replication has an evolutionarily conserved, non-templated 5&#39;-poly(A) leader in the 5&#39;-UTR. To ...