Financial support from MINECO/FEDER (grants SAF2015-64927-C2-2-R, RTI2018-094734-B-C22, and COV20/01100) is acknowledged. CGF acknowledged her IQS PhD Fellowship.

<ol>
	<li>Chumakov, K., Benn, C. S., Aaby, P., Kottilil, S., Gallo, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Can+existing+live+vaccines+prevent+COVID-19.">Can existing live vaccines prevent COVID-19.</a> Science. 368 (6496), 1187-1188 (2020).</li><li>Zhang, C., Maruggi, G., Shan, H., Li, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advances+in+mRNA+vaccines+for+infectious+diseases.">Advances in mRNA vaccines for infectious diseases.</a> Frontiers in Immunology. 10, 1-13 (2019).</li><li>Wherry, E. J., Jaffee, E. M., Warren, N., D'Souza, G., Ribas, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+did+we+get+a+COVID-19+vaccine+in+less+than+1+year.">How did we get a COVID-19 vaccine in less than 1 year.</a> Clinical Cancer Research. 27 (8), 2136-2138 (2021).</li><li>Folegatti, 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=Safety+and+immunogenicity+of+the+ChAdOx1+nCoV-19+vaccine+against+SARS-CoV-2:+a+preliminary+report+of+a+phase+1/2,+single-blind,+randomised+controlled+trial.">Safety and immunogenicity of the ChAdOx1 nCoV-19 vaccine against SARS-CoV-2: a preliminary report of a phase 1/2, single-blind, randomised controlled trial.</a> The Lancet. 396 (10249), 467-478 (2020).</li><li>Geall, A. J., Mandl, C. W., Ulmer, J. 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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=Systemic+RNA+delivery+to+dendritic+cells+exploits+antiviral+defence+for+cancer+immunotherapy.">Systemic RNA delivery to dendritic cells exploits antiviral defence for cancer immunotherapy.</a> Nature. 534 (7607), 396-401 (2016).</li><li>Milane, L., Amiji, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+approval+of+nanotechnology-based+SARS-CoV-2+mRNA+vaccines:+impact+on+translational+nanomedicine.">Clinical approval of nanotechnology-based SARS-CoV-2 mRNA vaccines: impact on translational nanomedicine.</a> Drug Delivery and Translational Research. 1 (4), 3 (2020).</li><li>Green, J. J., Langer, 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=A+combinatorial+polymer+library+approach+yields+insight+into+nonviral+gene+delivery.">A combinatorial polymer library approach yields insight into nonviral gene delivery.</a> Accounts of Chemical Research. 41 (6), 749-759 (2008).</li><li>Guerrero-C&#225;zares, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biodegradable+polymeric+nanoparticles+show+high+efficacy+and+specificity+at+DNA+delivery+to+human+glioblastoma+in+vitro+and+in+vivo.">Biodegradable polymeric nanoparticles show high efficacy and specificity at DNA delivery to human glioblastoma in vitro and in vivo.</a> ACS Nano. 8 (5), 5141-5153 (2014).</li><li>Kozielski, K. L., Tzeng, S. Y., Hurtado De Mendoza, B. A., Green, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioreducible+cationic+polymer-based+nanoparticles+for+efficient+and+environmentally+triggered+cytoplasmic+siRNA+delivery+to+primary+human+brain+cancer+cells.">Bioreducible cationic polymer-based nanoparticles for efficient and environmentally triggered cytoplasmic siRNA delivery to primary human brain cancer cells.</a> ACS Nano. 8 (4), 3232-3241 (2014).</li><li>Segovia, N., Dosta, P., Cascante, A., Ramos, V., Borr&#243;s, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oligopeptide-terminated+poly(&#946;-amino+ester)s+for+highly+efficient+gene+delivery+and+intracellular+localization.">Oligopeptide-terminated poly(&#946;-amino ester)s for highly efficient gene delivery and intracellular localization.</a> Acta Biomaterialia. 10 (5), 2147-2158 (2014).</li><li>Dosta, P., Segovia, N., Cascante, A., Ramos, V., Borr&#243;s, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+charge+tunability+as+a+powerful+strategy+to+control+electrostatic+interaction+for+high+efficiency+silencing,+using+tailored+oligopeptide-+modified+poly+(beta-amino+ester)s+(PBAEs).">Surface charge tunability as a powerful strategy to control electrostatic interaction for high efficiency silencing, using tailored oligopeptide- modified poly (beta-amino ester)s (PBAEs).</a> Acta Biomaterialia. 20, 82-93 (2015).</li><li>Fornaguera, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=mRNA+delivery+system+for+targeting+antigen-presenting+cells+in+vivo.">mRNA delivery system for targeting antigen-presenting cells in vivo.</a> Advanced Healthcare Materials. 7 (17), 180033 (2018).</li><li>Fornaguera, C., Castells-Sala, C., L&#225;zaro, M. &. #. 1. 9. 3. ;., Cascante, A., Borr&#243;s, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+an+optimized+freeze-drying+protocol+for+OM-PBAE+nucleic+acid+polyplexes.">Development of an optimized freeze-drying protocol for OM-PBAE nucleic acid polyplexes.</a> International Journal Pharmaceutics. 569, (2019).</li><li>Fornaguera, C., Solans, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analytical+methods+to+characterize+and+purify+polymeric+nanoparticles.">Analytical methods to characterize and purify polymeric nanoparticles.</a> International Journal of Polymer Science. , (2018).</li><li>Fornaguera, C., Solans, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+polymeric+nanoparticle+dispersions+for+biomedical+applications:+size,+surface+charge+and+stability.">Characterization of polymeric nanoparticle dispersions for biomedical applications: size, surface charge and stability.</a> Pharmaceutical Nanotechnology. 6 (3), 147-164 (2018).</li><li>Sahin, U., Karik&#243;, K., T&#252;reci, &. #. 2. 1. 4. ;. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MRNA-based+therapeutics-developing+a+new+class+of+drugs.">MRNA-based therapeutics-developing a new class of drugs.</a> Nature Reviews Drug Discovery. 13 (10), 759-780 (2014).</li><li>Fan, Y. N., 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=Cationic+lipid-assisted+nanoparticles+for+delivery+of+mRNA+cancer+vaccine.">Cationic lipid-assisted nanoparticles for delivery of mRNA cancer vaccine.</a> Biomaterials Science. 6 (11), 3009-3018 (2018).</li><li>Le Moignic, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preclinical+evaluation+of+mRNA+trimannosylated+lipopolyplexes+as+therapeutic+cancer+vaccines+targeting+dendritic+cells.">Preclinical evaluation of mRNA trimannosylated lipopolyplexes as therapeutic cancer vaccines targeting dendritic cells.</a> Journal of Controlled Release. 278, 110-121 (2018).</li><li>Banerji, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=mRNA+vaccines+to+prevent+COVID-19+disease+and+reported+allergic+reactions:+Current+evidence+and+approach.">mRNA vaccines to prevent COVID-19 disease and reported allergic reactions: Current evidence and approach.</a> Journal of Allergy and Clinical Immunology: In Practice. 9 (4), 1423-1437 (2021).</li><li>Kaczmarek, J. C., Kowalski, P. S., 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=Advances+in+the+delivery+of+RNA+therapeutics:+from+concept+to+clinical+reality.">Advances in the delivery of RNA therapeutics: from concept to clinical reality.</a> Genome Medicine. 9 (1), 1-16 (2017).</li><li>Dosta, 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=Delivery+of+anti-microRNA-712+to+inflamed+endothelial+cells+using+poly(&#946;-amino+ester)+nanoparticles+conjugated+with+VCAM-1+targeting+peptide.">Delivery of anti-microRNA-712 to inflamed endothelial cells using poly(&#946;-amino ester) nanoparticles conjugated with VCAM-1 targeting peptide.</a> Advanced Healthcare Materials. , 1-11 (2021).</li><li>Segovia, N., 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=Hydrogel+doped+with+nanoparticles+for+local+sustained+release+of+siRNA+in+breast+cancer.">Hydrogel doped with nanoparticles for local sustained release of siRNA in breast cancer.</a> Advanced Healthcare Materials. 4 (2), 271-280 (2015).</li></ol>

Authors have nothing to disclose nor any conflicts of interest.

After the outbreak of the Covid-19 pandemic last year, the importance of vaccines in terms of infectious disease control has manifested as a critical component8. Efforts from scientists worldwide have enabled the release to the market of many vaccines. For the first time in history, mRNA vaccines have demonstrated their previously hypothesized success, thanks to their rapid design because of their capacity to adapt to any novel antigen within some months5,<sup cl...

Infectious diseases have represented a severe threat to millions of human beings around the globe and are still one of the leading causes of death in some developing countries. Prophylactic vaccination has been one of the most effective interventions of modern society to prevent and control infectious diseases1,2. These critical milestones of science in 20th-century relevance have been remarked by the recent worldwide Covid-19 pandemic caused by the SARS-CoV-2 virus3. Recognizing the importance of having efficient vaccines to curtail the dissemination of the disease, cooperative efforts from all biomedical communities have successfully resulted in many prophylactic vaccines in the market in less than a year4.
Traditionally, vaccines were composed of attenuate (live, reduced virulence) or inactivated (death particles) viruses. However, for some diseases with no margin for safety errors, viral particles are not possible, and protein subunits are used instead. Nevertheless, subunits usually do not enable the combination of more than one epitope/antigen, and adjuvants are required to enhance vaccination potency5,6. Therefore, the need for novel vaccine types stands clear.
As demonstrated during the current pandemic, novel vaccine candidates based on nucleic acids can be advantageous in terms of avoiding long development processes and providing high versatility while producing, at the same time, a vital patient immunization. This is the case of mRNA vaccines, which were initially designed as experimental cancer vaccines. Thanks to their natural capacity to produce antigen-specific T-cell responses3,5,6,7. Being mRNA the molecule that encodes the antigenic protein, only changing the same, the vaccine can be rapidly tailored to immunize other variants of the same microorganism, different strains, other infectious microorganisms, or even become a cancer immunotherapeutic treatment. In addition, they are advantageous in terms of large-scale production costs. However, mRNA has a significant hurdle that hampers their naked administration: its stability and integrity are compromised in physiological media, full of nucleases. For this reason, the use of a nanometric carrier that protects it and vectorizes mRNA to the antigen-presenting cells is required2,8.
In this context, poly(beta aminoesters) (pBAE) are a class of biocompatible and biodegradable polymers that demonstrated a remarkable ability to complex mRNA in nanometric particles, thanks to their cationic charges9,10,11. These polymers are composed of ester bonds, which makes their degradation easy by esterases in physiological conditions. Among the pBAE library candidates, those functionalized with end cationic oligopeptides showed a higher capacity to form small nanoparticles to efficiently penetrate cells through endocytosis and transfect the encapsulated gene material. Furthermore, thanks to their buffering capacity, the acidification of the endosome compartment allows endosomal escape12,13. Namely, a specific kind of pBAE, including hydrophobic moieties on their backbone (the so-named C6 pBAE) to enhance their stability and end-oligopeptide combination (60% of polymer modified with a tri-lysine and 40% of the polymer with a tri-histidine) that selectively transfects antigen-presenting cells after parenteral administration and produce the mRNA encoded antigen presentation followed by mice immunization has been recently published14. In addition, it has also been demonstrated that these formulations could circumvent one of the main bottleneck steps of nanomedicine formulations: the possibility to freeze-dry them without losing their functionality, which enables long-term stability in soft dry environments15.
In this context, the objective of the current protocol is to make the procedure for the formation of the mRNA nanoparticles available to the scientific community by giving a description of the critical steps in the protocol and enabling the production of efficient vaccines for infectious diseases prevention and tumor treatment applications.
The following protocol describes the complete workout to synthesize oligopeptide end-modified poly(beta aminoesters) - OM-pBAE polymers that will further be used for nanoparticle synthesis. In the protocol, nanoparticles formulation is also included. In addition, critical steps for the success of the procedure and representative results are also provided to ensure that the resulting formulations accomplish the required quality control characterization features to define a positive or negative result. This protocol is summarized in Figure 1.

<table><tbody><tr><td>1,4-butanediol diacrylate</td><td>Sigma Aldrich</td><td>123048</td><td></td></tr><tr><td>1-hexylamine</td><td>Sigma Aldrich</td><td>219703</td><td></td></tr><tr><td>5-amino-1-pentanol</td><td>Sigma Aldrich</td><td>411744</td><td></td></tr><tr><td>Acetone</td><td>Panreac</td><td>141007</td><td></td></tr><tr><td>CD11b antibody</td><td>BD</td><td>550993</td><td></td></tr><tr><td>CD86 antibody</td><td>Bioligend</td><td>105007</td><td></td></tr><tr><td>Chlor hydroxhyde</td><td>Panreac</td><td>181023</td><td></td></tr><tr><td>Chloroform-d</td><td>Sigma Aldrich</td><td>151823</td><td></td></tr><tr><td>Cys-His-His-His peptide</td><td>Ontores</td><td>Custom</td><td></td></tr><tr><td>Cys-Lys-Lys-Lys peptide</td><td>Ontores</td><td>Custom</td><td></td></tr><tr><td>D&lt;sub&gt;2&lt;/sub&gt;O</td><td>Sigma Aldrich</td><td>151882</td><td></td></tr><tr><td>DEPC reagent for Rnase free water</td><td>Sigma Aldrich</td><td>D5758</td><td>This reagent is important to treat MilliQ water to remove any RNases of the buffers</td></tr><tr><td>Diethyl eter</td><td>Panreac</td><td>212770</td><td></td></tr><tr><td>dimethyl sulfoxide</td><td>Sigma Aldrich</td><td>276855</td><td></td></tr><tr><td>HEPES</td><td>Sigma Aldrich</td><td>H3375</td><td></td></tr><tr><td>mRNA EGFP</td><td>TriLink Technologies</td><td>L-7601</td><td></td></tr><tr><td>mRNA OVA</td><td>TriLink Technologies</td><td>L-7610</td><td></td></tr><tr><td>RiboGreen kit</td><td>ThermoFisher</td><td>R11490</td><td></td></tr><tr><td>sodium acetate</td><td>Sigma Aldrich</td><td>71196</td><td></td></tr><tr><td>sucrose</td><td>Sigma Aldrich</td><td>S0389</td><td></td></tr><tr><td>Trifluoroacetic acid</td><td>Sigma Aldrich</td><td>302031</td><td></td></tr><tr><td>Trypsin-EDTA</td><td>Fisher Scientific</td><td>11570626</td><td></td></tr><tr><td>&amp;alpha;-mouse AlexaFluor488 antibody</td><td>Abcam</td><td>Ab450105</td><td></td></tr><tr><td>&lt;strong&gt;Equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Nanoparticle Tracking Analyzer</td><td>Malvern Panalytical</td><td>NanoSight NS300</td><td></td></tr><tr><td>Nuclear Magnetic Ressonance Spectrometer</td><td>Varian</td><td>400 MHz</td><td></td></tr><tr><td>ZetaSizer</td><td>Malvern Panalytical</td><td>Nano ZS</td><td>For zeta potential and hydrodynamic size determination</td></tr><tr><td>&lt;strong&gt;Software&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>NanoSight NTA software</td><td>Malvern Panalytical</td><td>MAN0515-02-EN-00</td><td></td></tr><tr><td>NovoExpress Software</td><td>Agilent</td><td>Not specified</td><td></td></tr><tr><td>ZetaSizer software</td><td>Malvern Panalytical</td><td>DTS Application</td><td>To analyze surface charge and hydrodynamic sizes</td></tr></tbody></table>

synthesis and characterization of mrna-loaded poly(beta aminoesters) nanoparticles for vaccination purposes

Vaccination has been one of the major successes of modern society and is indispensable in controlling and preventing disease. Traditional vaccines were composed of entire or fractions of the infectious agent. However, challenges remain, and new vaccine technologies are mandatory. In this context, the use of mRNA for immunizing purposes has shown an enhanced performance, as demonstrated by the speedy approval of two mRNA vaccines preventing SARS-CoV-2 infection. Beyond success in preventing viral infections, mRNA vaccines can also be used for therapeutic cancer applications.
Nevertheless, the instability of mRNA and its fast clearance from the body due to the presence of nucleases makes its naked delivery not possible. In this context, nanomedicines, and specifically polymeric nanoparticles, are critical mRNA delivery systems. Thus, the aim of this article is to describe the protocol for the formulation and test of an mRNA vaccine candidate based on the proprietary polymeric nanoparticles. The synthesis and chemical characterization of the poly(beta aminoesters) polymers used, their complexation with mRNA to form nanoparticles, and their lyophilization methodology will be discussed here. This is a crucial step for decreasing storage and distribution costs. Finally, the required tests to demonstrate their capacity to in vitro transfect and mature model dendritic cells will be indicated. This protocol will benefit the scientific community working on vaccination because of its high versatility that enables these vaccines to prevent or cure a wide variety of diseases.

Polymer synthesis and characterization 
The OM-pBAE synthesis procedure&#160;is given in Figure 2. As Figure 2A shows, the first step to obtain the OM-pBAE is to synthesize the C6-pBAE by adding the amines (1-hexylamine and 5-amino-1-pentanol, ratio 1:1) to the diacrylate (1,4-butanediol diacrylate). This reaction is carried out at 90 &#176;C for 20 h and with constant stirring. Afterward, a solution of oligopeptides is added to a solution ...

Watch this Scientific Journal Video about Synthesis and Characterization of mRNA-Loaded PolyBeta Aminoesters Nanoparticles for Vaccination Purposes at JoVE.com

Synthesis and Characterization of mRNA-Loaded PolyBeta Aminoesters Nanoparticles for Vaccination Purposes

Here, a simple protocol is presented for producing mRNA nanoparticles based on poly(beta aminoester) polymers, easy to be tailored by changing the encapsulated mRNA. The workflow for synthesizing the polymers, the nanoparticles, and their in vitro essential characterization are also described. A proof-of-concept regarding immunization is also added.

Synthesis and Characterization of mRNA-Loaded Poly(Beta Aminoesters) Nanoparticles for Vaccination Purposes

Vaccination has been one of the major successes of modern society and is indispensable in controlling and preventing disease. Traditional vaccines were ...

synthesis-characterization-mrna-loaded-poly-beta-aminoesters

Research

JoVE Journal

Bioengineering

4.4K Views.  Universitat Ramon Llull (URL). Dit protocol is belangrijk omdat het aantoont hoe polymere nanodeeltjes, ingekapselde nucleïnezuren in één eenvoudige stap kunnen worden ingekapseld. De belangrijkste voordelen van deze techniek zijn veelzijdigheid, omdat deze kan worden toegepast op verschillende nucleïnezuren en celtypen. Het gebruik van eenvoudige procedures voor deeltjesvoorbereiding, zoals pipetteren op en neer, en de mogelijkheid om de stabiliteit van de nanodeeltjes en trommelcondities te verlengen door lyofilisati...

Video: Synthesis and Characterization of mRNA-Loaded PolyBeta Aminoesters Nanoparticles for Vaccination Purposes

Evaluation of Polymeric Gene Delivery Nanoparticles by Nanoparticle Tracking Analysis and High-throughput Flow Cytometry

Non-viral gene delivery using polymeric nanoparticles has emerged as an attractive approach for gene therapy to treat genetic diseases1 and as a technology for regenerative medicine2. Unlike viruses, which have significant safety issues, polymeric nanoparticles can be designed to be non-toxic, non-immunogenic, non-mutagenic, easier to synthesize, chemically versatile, capable of carrying larger nucleic acid cargo and biodegradable and/or environmentally responsive. Cationic polymers self-assemble with negatively charged DNA via electrostatic interaction to form complexes on the order of 100 nm that are commonly termed polymeric nanoparticles. Examples of biomaterials used to form nanoscale polycationic gene delivery nanoparticles include polylysine, polyphosphoesters, poly(amidoamines)s and polyethylenimine (PEI), which is a non-degradable off-the-shelf cationic polymer commonly used for nucleic acid delivery1,3 . Poly(beta-amino ester)s (PBAEs) are a newer class of cationic polymers4 that are hydrolytically degradable5,6 and have been shown to be effective at gene delivery to hard-to-transfect cell types such as human retinal endothelial cells (HRECs)7, mouse mammary epithelial cells8, human brain cancer cells9 and macrovascular (human umbilical vein, HUVECs) endothelial cells10.
A new protocol to characterize polymeric nanoparticles utilizing nanoparticle tracking analysis (NTA) is described. In this approach, both the particle size distribution and the distribution of the number of plasmids per particle are obtained11. In addition, a high-throughput 96-well plate transfection assay for rapid screening of the transfection efficacy of polymeric nanoparticles is presented. In this protocol, poly(beta-amino ester)s (PBAEs) are used as model polymers and human retinal endothelial cells (HRECs) are used as model human cells. This protocol can be easily adapted to evaluate any polymeric nanoparticle and any cell type of interest in a multi-well plate format.

A protocol for nanoparticle tracking analysis (NTA) and high-throughput flow cytometry to evaluate polymeric gene delivery nanoparticles is described. NTA is utilized to characterize the nanoparticle particle size distribution and the plasmid per particle distribution. High-throughput flow cytometry enables quantitative transfection efficacy evaluation for a library of gene delivery biomaterials.

Non-viral gene delivery using polymeric nanoparticles has emerged as an attractive approach for gene therapy to treat genetic diseases1 and as a ...

Using Lipid Nanoparticles for the Delivery of Chemically Modified mRNA into Mammalian Cells

In recent years, chemically modified messenger RNA (mRNA) has emerged as a potent nucleic acid molecule for developing a wide range of therapeutic applications, including a novel class of vaccines, protein replacement therapies, and immune therapies. Among delivery vectors, lipid nanoparticles are found to be safer and more effective in delivering RNA molecules (e.g., siRNA, miRNA, mRNA) and a few products are already in clinical use. To demonstrate lipid nanoparticle-mediated mRNA delivery, we present an optimized protocol for the synthesis of functional me1&#936;-UTP modified eGFP mRNA, the preparation of cationic liposomes, the electrostatic complex formation of mRNA with cationic liposomes, and the evaluation of transfection efficiencies in mammalian cells. The results demonstrate that these modifications efficiently improved the stability of mRNA when delivered with cationic liposomes and increased the eGFP mRNA translation efficiency and stability in mammalian cells. This protocol can be used to synthesize the desired mRNA and transfect with cationic liposomes for target gene expression in mammalian cells.

The protocol presents in vitro transcription (IVT) of chemically modified mRNA, cationic liposome preparation, and functional analysis of liposome enabled mRNA transfections in mammalian cells.

In recent years, chemically modified messenger RNA (mRNA) has emerged as a potent nucleic acid molecule for developing a wide range of therapeutic ...

Biochemistry

Whole-animal Imaging and Flow Cytometric Techniques for Analysis of Antigen-specific CD8+ T Cell Responses after Nanoparticle Vaccination

Traditional vaccine adjuvants, such as alum, elicit suboptimal CD8+ T cell responses. To address this major challenge in vaccine development, various nanoparticle systems have been engineered to mimic features of pathogens to improve antigen delivery to draining lymph nodes and increase antigen uptake by antigen-presenting cells, leading to new vaccine formulations optimized for induction of antigen-specific CD8+ T cell responses. In this article, we describe the synthesis of a &#8220;pathogen-mimicking&#8221; nanoparticle system, termed interbilayer-crosslinked multilamellar vesicles (ICMVs) that can serve as an effective vaccine carrier for co-delivery of subunit antigens and immunostimulatory agents and elicitation of potent cytotoxic CD8+ T lymphocyte (CTL) responses. We describe methods for characterizing hydrodynamic size and surface charge of vaccine nanoparticles with dynamic light scattering and zeta potential analyzer and present a confocal microscopy-based procedure to analyze nanoparticle-mediated antigen delivery to draining lymph nodes. Furthermore, we show a new bioluminescence whole-animal imaging technique utilizing adoptive transfer of luciferase-expressing, antigen-specific CD8+ T cells into recipient mice, followed by nanoparticle vaccination, which permits non-invasive interrogation of expansion and trafficking patterns of CTLs in real time. We also describe tetramer staining and flow cytometric analysis of peripheral blood mononuclear cells for longitudinal quantification of endogenous T cell responses in mice vaccinated with nanoparticles.

We describe whole-animal imaging and flow cytometry-based techniques for monitoring expansion of antigen-specific CD8+ T cells in response to immunization with nanoparticles in a murine model of vaccination.

Traditional vaccine adjuvants, such as alum, elicit suboptimal CD8+ T cell responses. To address this major challenge in vaccine development, various ...

Immunology and Infection

Generation of Cationic Nanoliposomes for the Efficient Delivery of In Vitro Transcribed Messenger RNA

The development of messenger RNA (mRNA)-based therapeutics for the treatment of various diseases becomes more and more important because of the positive properties of in vitro transcribed (IVT) mRNA. With the help of IVT mRNA, the de novo synthesis of a desired protein can be induced without changing the physiological state of the target cell. Moreover, protein biosynthesis can be precisely controlled due to the transient effect of IVT mRNA.
For the efficient transfection of cells, nanoliposomes (NLps) may represent a safe and efficient delivery vehicle for therapeutic mRNA. This study describes a protocol to generate safe and efficient cationic NLps consisting of DC-cholesterol and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) as a delivery vector for IVT mRNA. NLps having a defined size, a homogeneous distribution, and a high complexation capacity, and can be produced using the dry-film method. Moreover, we present different test systems to analyze their complexation and transfection efficacies using synthetic enhanced green fluorescent protein (eGFP) mRNA, as well as their effect on cell viability. Overall, the presented protocol provides an effective and safe approach for mRNA complexation, which may advance and improve the administration of therapeutic mRNA.

Generation of Cationic Nanoliposomes for the Efficient Delivery of In Vitro Transcribed Messenger RNA

Here we describe a protocol for the generation of cationic nanoliposomes, which is based on the dry-film method and can be used for the safe and efficient delivery of in vitro transcribed messenger RNA.

The development of messenger RNA (mRNA)-based therapeutics for the treatment of various diseases becomes more and more important because of the positive ...

Production of E. coli-expressed Self-Assembling Protein Nanoparticles for Vaccines Requiring Trimeric Epitope Presentation

Self-assembling protein nanoparticles (SAPNs) function as repetitive antigen displays and can be used to develop a wide range of vaccines for different infectious diseases. In this article we demonstrate a method to produce a SAPN core containing a six-helix bundle (SHB) assembly that is capable of presenting antigens in a trimeric conformation. We describe the expression of the SHB-SAPN in an E. coli system, as well as the necessary protein purification steps. We included an isopropanol wash step to reduce the residual bacterial lipopolysaccharide. As an indication of the protein identity and purity, the protein reacted with known monoclonal antibodies in Western blot analyses. After refolding, the size of the particles fell in the expected range (20 to 100 nm), which was confirmed by dynamic light scattering, nanoparticle tracking analysis, and transmission electron microscopy. The methodology described here is optimized for the SHB-SAPN, however, with only slight modifications it can be applied to other SAPN constructs. This method is also easily transferable to large scale production for GMP manufacturing for human vaccines.

Production of E. coli-expressed Self-Assembling Protein Nanoparticles for Vaccines Requiring Trimeric Epitope Presentation

A detailed method is provided here describing the purification, refolding, and characterization of self-assembling protein nanoparticles (SAPNs) for use in vaccine development.

Self-assembling protein nanoparticles (SAPNs) function as repetitive antigen displays and can be used to develop a wide range of vaccines for different ...

A "Plug-And-Display" Nanoparticle Vaccine Platform Based on Outer Membrane Vesicles Displaying SARS-CoV-2 Receptor-Binding Domain

Biomimetic nanoparticles obtained from bacteria or viruses have attracted substantial interest in vaccine research and development. Outer membrane vesicles (OMVs) are mainly secreted by gram-negative bacteria during average growth, with a nano-sized diameter and self-adjuvant activity, which may be ideal for vaccine delivery. OMVs have functioned as a multifaceted delivery system for proteins, nucleic acids, and small molecules. To take full advantage of the biological characteristics of OMVs, bioengineered Escherichia coli-derived&#160;OMVs were utilized as a carrier and SARS-CoV-2 receptor-binding domain (RBD) as an antigen to construct a &#34;Plug-and-Display&#34; vaccine platform. The SpyCatcher (SC) and SpyTag (ST) domains in Streptococcus pyogenes were applied to conjugate OMVs and RBD. The Cytolysin A (ClyA) gene was translated with the SC gene as a fusion protein after plasmid transfection, leaving a reactive site on the surface of the OMVs. After mixing RBD-ST in a conventional buffer system overnight, covalent binding was formed between the OMVs and RBD. Thus, a multivalent-displaying OMV vaccine was achieved. By replacing with diverse antigens, the OMVs vaccine platform can efficiently display a variety of heterogeneous antigens, thereby potentially rapidly preventing infectious disease epidemics. This protocol describes a precise method for constructing the OMV vaccine platform, including production, purification, bioconjugation, and characterization.

The present protocol describes the bioengineering of outer membrane vesicles to be a "Plug-and-Display" vaccine platform, including production, purification, bioconjugation, and characterization.

Biomimetic nanoparticles obtained from bacteria or viruses have attracted substantial interest in vaccine research and development. Outer membrane ...

Fabrication of Pulsatile Polymeric Microparticles Encapsulating Rabies Antigen

The current guidelines for rabies post-exposure prophylaxis require multiple injections administered over several weeks. This can be disproportionately burdensome to those living in low- and middle-income countries (LMICs), where the majority of deadly exposures to rabies occur. Different drug delivery strategies have been explored to condense vaccine regimens to a single injection by encapsulating antigens into polymeric particles. However, harsh stressors during the encapsulation process can cause denaturation of the encapsulated antigen. This article describes a method for encapsulating the rabies virus (RABV) antigen into polymeric microparticles that exhibit tunable pulsatile release. This method, termed Particles Uniformly Liquified and Sealed to Encapsulate Drugs (PULSED), generates microparticles using soft lithography to create inverse polydimethylsiloxane (PDMS) molds from a multi-photon, 3D-printed master mold. Poly(lactic-co-glycolic acid) (PLGA) films are then compression-molded into the PDMS molds to generate open-faced cylinders that are filled with concentrated RABV using a piezoelectric dispensing robot. These microstructures are then sealed by heating the top of the particles, allowing the material to flow and form a continuous, nonporous polymeric barrier. Post-fabrication, an enzyme-linked immunosorbent assay (ELISA) specific to the detection of intact trimeric rabies virus glycoprotein is used to confirm the high recovery of immunogenic antigen from the microparticles.

This method describes the encapsulation of the rabies antigen into biodegradable polymeric microparticles with structural and material properties that enable pulsatile release after a predetermined delay. Enzyme-linked immunosorbent assay (ELISA) assessment of the antigen retrieved from the particle core confirms the presence of intact trimeric rabies virus glycoprotein through particle fabrication.

The current guidelines for rabies post-exposure prophylaxis require multiple injections administered over several weeks. This can be disproportionately ...

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.

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.

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

Evaluating the Immune Response of a Nanoemulsion Adjuvant Vaccine Against Methicillin-Resistant Staphylococcus aureus (MRSA) Infection

Nanoemulsion adjuvant vaccines have attracted extensive attention because of their small particle size, high thermal stability, and ability to induce validly immune responses. However, establishing a series of comprehensive protocols to evaluate the immune response of a novel nanoemulsion adjuvant vaccine is vital. Therefore, this article features a rigorous procedure to determine the physicochemical characteristics of a vaccine (by transmission electron microscopy [TEM], atomic force microscopy [AFM], and dynamic light scattering [DLS]), the stability of the vaccine antigen and system (by a high-speed centrifuge test, a thermodynamic stability test, SDS-PAGE, and western blot), and the specific immune response (IgG1, IgG2a, and IgG2b). Using this approach, researchers can evaluate accurately&#160;the protective effect of a novel nanoemulsion adjuvant vaccine in a lethal MRSA252 mouse model. With these protocols, the most promising nanoemulsion vaccine adjuvant in terms of effective adjuvant potential can be identified. In addition, the methods can help optimize novel vaccines for future development.

Evaluating the Immune Response of a Nanoemulsion Adjuvant Vaccine Against Methicillin-Resistant Staphylococcus aureus MRSA Infection

The present protocol prepares and evaluates the physical properties, immune response, and in vivo protective effect of a novel nanoemulsion adjuvant vaccine.

Nanoemulsion adjuvant vaccines have attracted extensive attention because of their small particle size, high thermal stability, and ability to induce ...

Production of Near-Infrared Sensitive, Core-Shell Vaccine Delivery Platform

Vaccine delivery strategies that can limit the exposure of cargo to organic solvent while enabling novel release profiles are crucial for improving immunization coverage worldwide. Here, a novel injectable, ultraviolet- curable and delayed burst release- enabling vaccine delivery platform called polybubbles is introduced. Cargo was injected into polyester-based polybubbles that were formed in 10% carboxymethycellulose -based aqueous solution. This paper includes protocols to maintain spherical shape of the polybubbles and optimize cargo placement and retention to maximize the amount of cargo within the polybubbles. To ensure safety, chlorinated solvent content within the polybubbles were analyzed using neutron activation analysis. Release studies were conducted with small molecules as cargo within the polybubble to confirm delayed burst release. To further show the potential for on-demand delivery of the cargo, gold nanorods were mixed within the polymer shell to enable near-infrared laser activation.

This article describes the protocols used to produce a novel vaccine delivery platform, &#34;polybubbles,&#34; to enable delayed burst release. Polyesters including poly(lactic-co-glycolic acid) and polycaprolactone were used to form the polybubbles and small molecules and antigen were used as cargo.

Vaccine delivery strategies that can limit the exposure of cargo to organic solvent while enabling novel release profiles are crucial for improving ...

Synthesis and Characterization of mRNA-Loaded Poly(Beta Aminoesters) Nanoparticles for Vaccination Purposes

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