Name: testing the in vitro and in vivo efficiency of mrna-lipid nanoparticles formulated by microfluidic mixing
Uploaded: 2023-01-20T13:20:00
Description: Watch this Scientific Journal Video about Testing the In Vitro and In Vivo Efficiency of mRNA-Lipid Nanoparticles Formulated by Microfluidic Mixing at JoVE.com

M.J.M. acknowledges support from a US National Institutes of Health (NIH) Director&#8217;s New Innovator Award (DP2 TR002776), a Burroughs Wellcome Fund Career Award at the Scientific Interface (CASI), a US National Science Foundation CAREER award (CBET-2145491), and additional funding from the National Institutes of Health (NCI R01 CA241661, NCI R37 CA244911, and NIDDK R01 DK123049).

NOTE: Always maintain RNase-free conditions when formulating mRNA-LNPs by wiping the surfaces and equipment with a surface decontaminant for RNases and DNA. Use only RNase-free tips and reagents.
All the animal procedures were performed in accordance with the Guidelines for the Care and Use of Laboratory Animals at the University of Pennsylvania and a protocol approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Pennsylvania.
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<ol>
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D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+single+administration+of+CRISPR/Cas9+lipid+nanoparticles+achieves+robust+and+persistent+in+vivo+genome+editing.">A single administration of CRISPR/Cas9 lipid nanoparticles achieves robust and persistent in vivo genome editing.</a> Cell Reports. 22 (9), 2227-2235 (2018).</li><li>Truong, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lipid+nanoparticle-targeted+mRNA+therapy+as+a+treatment+for+the+inherited+metabolic+liver+disorder+arginase+deficiency.">Lipid nanoparticle-targeted mRNA therapy as a treatment for the inherited metabolic liver disorder arginase deficiency.</a> Proceedings of the National Academy of Sciences of the United States of America. 116 (42), 21150-21159 (2019).</li><li>Cheng, Q., 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=Dendrimer-based+lipid+nanoparticles+deliver+therapeutic+FAH+mRNA+to+normalize+liver+function+and+extend+survival+in+a+mouse+model+of+hepatorenal+tyrosinemia+type+I.">Dendrimer-based lipid nanoparticles deliver therapeutic FAH mRNA to normalize liver function and extend survival in a mouse model of hepatorenal tyrosinemia type I.</a> Advanced Materials. 30 (52), 1805308 (2018).</li><li>Sedic, 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+evaluation+of+lipid+nanoparticle-formulated+modified+mRNA+in+the+Sprague-Dawley+rat+and+cynomolgus+monkey.">Safety evaluation of lipid nanoparticle-formulated modified mRNA in the Sprague-Dawley rat and cynomolgus monkey.</a> Veterinary Pathology. 55 (2), 341-354 (2018).</li><li>Veiga, 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=Cell+specific+delivery+of+modified+mRNA+expressing+therapeutic+proteins+to+leukocytes.">Cell specific delivery of modified mRNA expressing therapeutic proteins to leukocytes.</a> Nature Communications. 9 (1), 4493 (2018).</li><li>Pattipeiluhu, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anionic+lipid+nanoparticles+preferentially+deliver+mRNA+to+the+hepatic+reticuloendothelial+system.">Anionic lipid nanoparticles preferentially deliver mRNA to the hepatic reticuloendothelial system.</a> Advanced Materials. 34 (16), 2201095 (2022).</li><li>Rosenblum, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CRISPR-Cas9+genome+editing+using+targeted+lipid+nanoparticles+for+cancer+therapy.">CRISPR-Cas9 genome editing using targeted lipid nanoparticles for cancer therapy.</a> Science Advances. 6 (47), (2020).</li><li>Fenton, O. 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With this workflow, a variety of mRNA-LNPs can be formulated and tested for their in vitro and in vivo efficiency. Ionizable lipids and excipients can be swapped out and combined at different molar ratios and different ionizable lipid to mRNA weight ratios to produce mRNA-LNPs with differing physicochemical properties22. Here, we formulated C12-200 mRNA-LNPs with a molar ratio of 35/16/46.5/2.5 (ionizable lipid:helper lipid:cholesterol:lipid-PEG) at a 10:1 ionizable lipid to mRNA...

Lipid nanoparticles (LNPs) have demonstrated great promise in recent years in the field of non-viral gene therapy. In 2018, the United States Food and Drug Administration (FDA) approved the first-ever RNA interference (RNAi) therapeutic, Onpattro by Alnylam, for the treatment of hereditary transthyretin amyloidosis1,2,3,4. This was an important step forward for lipid nanoparticles and RNA-based therapies. More recently, Moderna and Pfizer/BioNTech received FDA approvals for their mRNA-LNP vaccines against SARS-CoV-24,5. In each of these LNP-based nucleic acid therapies, the LNP serves to protect its cargo from degradation by nucleases and facilitate potent intracellular delivery6,7. While LNPs have seen success in RNAi therapies and vaccine applications, mRNA-LNPs have also been explored for use in protein replacement therapies8 as well as for the co-delivery of Cas9 mRNA and guide RNA for the delivery of the CRISPR-Cas9 system for gene editing9. However, there is no one specific formulation that is well-suited for all applications, and subtle changes in the LNP formulation parameters can greatly affect the potency and biodistribution in vivo8,10,11. Thus, individual mRNA-LNPs must be developed and evaluated to determine the optimal formulation for each LNP-based therapy.
LNPs are commonly formulated with four lipid components: an ionizable lipid, a phospholipid, cholesterol, and a lipid-anchored polyethylene-glycol (PEG) conjugate (lipid-PEG)11,12,13. The potent intracellular delivery facilitated by LNPs relies, in part, on the ionizable lipid component12. This component is neutral at physiological pH but becomes positively charged in the acidic environment of the endosome11. This change in ionic charge is thought to be a key contributor to endosomal escape12,14,15. In addition to the ionizable lipid, the phospholipid (helper lipid) component improves the encapsulation of the cargo and aids in endosomal escape, the cholesterol offers stability and enhances membrane fusion, and the lipid-PEG minimizes LNP aggregation and opsonization in circulation10,11,14,16. To formulate the LNP, these lipid components are combined in an organic phase, typically ethanol, and mixed with an aqueous phase containing the nucleic acid cargo. The LNP formulation process is very versatile in that it allows for different components to be easily substituted and combined at different molar ratios in order to formulate many LNP formulations&#160;with a multitude of physicochemical properties10,17. However, when exploring this vast variety of LNPs, it is crucial that each formulation is evaluated using a standardized procedure to accurately measure the differences in characterization and performance.
Here, the complete workflow for the formulation of mRNA-LNPs and the assessment of their performance in cells and animals is outlined.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.1 M Hydrochloric Acid</td>
			<td>Sigma</td>
			<td>7647-01-0</td>
			<td></td>
		</tr>
		<tr>
			<td>0.22 &#956;m Syringe Filters</td>
			<td>Genesee</td>
			<td>25-243</td>
			<td></td>
		</tr>
		<tr>
			<td>1 mL BD Slip Tip Syringe</td>
			<td>BD</td>
			<td>309659</td>
			<td></td>
		</tr>
		<tr>
			<td>1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (ammonium salt) (C14-PEG2000)</td>
			<td>Avanti Polar Lipids</td>
			<td>880150P</td>
			<td></td>
		</tr>
		<tr>
			<td>1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE)</td>
			<td>Avanti Polar Lipids</td>
			<td>850725P</td>
			<td></td>
		</tr>
		<tr>
			<td>1.5 mL Eppendorf Tubes</td>
			<td>Fisher Scientific</td>
			<td>05-408-129</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL Conical Tubes</td>
			<td>Fisher Scientific</td>
			<td>14-959-70C</td>
			<td></td>
		</tr>
		<tr>
			<td>200 proof Ethanol</td>
			<td>Decon Labs</td>
			<td>2716</td>
			<td></td>
		</tr>
		<tr>
			<td>23G Needles</td>
			<td>Fisher Scientific</td>
			<td>14-826-6C</td>
			<td></td>
		</tr>
		<tr>
			<td>3 mL BD Disposable Syringes with Luer-Lok tips</td>
			<td>Fisher Scientific</td>
			<td>14-823-435</td>
			<td></td>
		</tr>
		<tr>
			<td>3 mL Dialysis Cassettes</td>
			<td>Thermo Scientific</td>
			<td>A52976</td>
			<td></td>
		</tr>
		<tr>
			<td>96 Well Black Wall Black Bottom Plate</td>
			<td>Fisher Scientific</td>
			<td>07-000-135</td>
			<td></td>
		</tr>
		<tr>
			<td>96 Well White/Clear Bottom Plate, TC Surface</td>
			<td>Thermo Scientific</td>
			<td>165306</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium Acetate, 1 Kilogram</td>
			<td>Research Products International</td>
			<td>&#160;631-61-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium Citrate dibasic</td>
			<td>SIgma</td>
			<td>3012-65-5</td>
			<td></td>
		</tr>
		<tr>
			<td>BD Luer-Lok Syringe sterile, single use, 5 mL</td>
			<td>BD</td>
			<td>309646</td>
			<td></td>
		</tr>
		<tr>
			<td>C12-200 Ionizable Lipid</td>
			<td>Cayman Chemical</td>
			<td>36699</td>
			<td></td>
		</tr>
		<tr>
			<td>C57BL/6 Mice</td>
			<td>Jackson Laboratory</td>
			<td>000664</td>
			<td></td>
		</tr>
		<tr>
			<td>Cholesterol</td>
			<td>Sigma</td>
			<td>57-88-5</td>
			<td></td>
		</tr>
		<tr>
			<td>CleanCap FLuc mRNA (5moU)</td>
			<td>TriLink Biotechnologies</td>
			<td>L-7202</td>
			<td></td>
		</tr>
		<tr>
			<td>Disposable cuvettes</td>
			<td>Fisher Scientific</td>
			<td>14955129</td>
			<td></td>
		</tr>
		<tr>
			<td>D-Luciferin, Potassium Salt</td>
			<td>Thermo Scientific</td>
			<td>L2916</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM, high glucose</td>
			<td>Thermofisher Scientific</td>
			<td>11965-084</td>
			<td></td>
		</tr>
		<tr>
			<td>Exel Insulin Syringes - 0.5 mL</td>
			<td>Fisher Scientific</td>
			<td>1484132</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Corning</td>
			<td>35-010-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Hep G2 [HEPG2]</td>
			<td>ATCC</td>
			<td>HB-8065</td>
			<td></td>
		</tr>
		<tr>
			<td>HyPure Molecular Biology Grade Water</td>
			<td>Cytiva</td>
			<td>SH30538.03</td>
			<td></td>
		</tr>
		<tr>
			<td>Infinite 200 PRO Plate Reader</td>
			<td>Tecan</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>IVIS Spectrum In Vivo Imaging System</td>
			<td>Perkin Elmer</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Large Kimwipes</td>
			<td>Fisher Scientific</td>
			<td>06-666-11D</td>
			<td></td>
		</tr>
		<tr>
			<td>Luciferase Assay Kit</td>
			<td>Promega</td>
			<td>E4550</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoAssemblr Ignite Cartridges - Classic - 100 Pack</td>
			<td>Precision Nanosystems</td>
			<td>NIN0065</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoAssemblr Ignite Instrument</td>
			<td>Precision Nanosystems</td>
			<td>NIN0001</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS - Phosphate-Buffered Saline (10x) pH 7.4, RNase-free</td>
			<td>Thermo Scientific</td>
			<td>AM9624</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Thermofisher Scientific</td>
			<td>15140122</td>
			<td></td>
		</tr>
		<tr>
			<td>QB Citrate Buffer, (Citrate 100 mM) pH 3.0</td>
			<td>Teknova</td>
			<td>Q2442</td>
			<td></td>
		</tr>
		<tr>
			<td>Quant-it RiboGreen RNA Assay Kit</td>
			<td>Thermo Scientific</td>
			<td>R11490</td>
			<td></td>
		</tr>
		<tr>
			<td>Reporter Lysis 5x Buffer</td>
			<td>Promega</td>
			<td>E3971</td>
			<td></td>
		</tr>
		<tr>
			<td>RNase Away Surface Decontaminant</td>
			<td>Thermofisher Scientific</td>
			<td>7000TS1</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>Sigma</td>
			<td>7647-14-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Hydroxide</td>
			<td>Sigma</td>
			<td>1310-73-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Phosphate</td>
			<td>Sigma</td>
			<td>7601-54-9</td>
			<td></td>
		</tr>
		<tr>
			<td>TNS reagent (6-(p-Toluidino)-2-naphthalenesulfonic acid sodium salt)</td>
			<td>Sigma</td>
			<td>T9792</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma</td>
			<td>9036-19-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Zetasizer</td>
			<td>Malvern Panalytical</td>
			<td>NanoZS</td>
			<td></td>
		</tr>
	</tbody>
</table>

testing the in vitro and in vivo efficiency of mrna-lipid nanoparticles formulated by microfluidic mixing

Lipid nanoparticles (LNPs) have attracted widespread attention recently with the successful development of the COVID-19 mRNA vaccines by Moderna and Pfizer/BioNTech. These vaccines have demonstrated the efficacy of mRNA-LNP therapeutics and opened the door for future clinical applications. In mRNA-LNP systems, the LNPs serve as delivery platforms that protect the mRNA cargo from degradation by nucleases and mediate their intracellular delivery. The LNPs are typically composed of four components: an ionizable lipid, a phospholipid, cholesterol, and a lipid-anchored polyethylene glycol (PEG) conjugate (lipid-PEG). Here, LNPs encapsulating mRNA encoding firefly luciferase are formulated by microfluidic mixing of the organic phase containing LNP lipid components and the aqueous phase containing mRNA. These mRNA-LNPs are then tested in vitro to evaluate their transfection efficiency in HepG2 cells using a bioluminescent plate-based assay. Additionally, mRNA-LNPs are evaluated in vivo in C57BL/6 mice following an intravenous injection via the lateral tail vein. Whole-body bioluminescence imaging is performed by using an in vivo imaging system. Representative results are shown for the mRNA-LNP characteristics, their transfection efficiency in HepG2 cells, and the total luminescent flux in C57BL/6 mice.

mRNA-LNPs were formulated using a microfluidic instrument that possessed an average hydrodynamic diameter of 76.16 nm and a polydispersity index of 0.098. The pKa of the mRNA-LNPs was found to be 5.75 by performing a TNS assay18. The encapsulation efficiency for these mRNA-LNPs was calculated to be 92.3% by using the modified fluorescence assay and equation 4.4. The overall RNA concentration that was used for the cell treatment and animal dosing was 40.24 ng/&#...

Watch this Scientific Journal Video about Testing the In Vitro and In Vivo Efficiency of mRNA-Lipid Nanoparticles Formulated by Microfluidic Mixing at JoVE.com

Testing the In Vitro and In Vivo Efficiency of mRNA-Lipid Nanoparticles Formulated by Microfluidic Mixing

Here, a protocol for formulating lipid nanoparticles (LNPs) that encapsulate mRNA encoding firefly luciferase is presented. These LNPs were tested for their potency in vitro in HepG2 cells and in vivo in C57BL/6 mice.

Testing the In Vitro and In Vivo Efficiency of mRNA-Lipid Nanoparticles Formulated by Microfluidic Mixing

Lipid nanoparticles (LNPs) have attracted widespread attention recently with the successful development of the COVID-19 mRNA vaccines by Moderna and ...

This protocol can be used to formulate consistent lipid nanoparticles encapsulating MRA. Formulation parameters can be tuned and the various lipid nanoparticles can be evaluated for their potency and biodistribution. A standardized protocol for lipid nanoparticle formulation and in vitro and in vivo testing can be used to formulate consistent lipid nanoparticles that can be compared with each other.There are a lot of small details to keep in mind when formulating and evaluating nanoparticle potency, but which details accounted for? Preparing the formulation should not be difficult. Begin by filling a clean, four liter beaker with 200 to 300 milliliters of fresh 10X PBS, and diluting it to 1X with ultrapure water.Ensure the final volume of PBS is between two and three liters. Place dialysis cassettes of the appropriate capacity for the lipid nanoparticle, or LNP formulation, into the field beaker. Make the ten-fold dilution of a 100 millimolar citric acid buffer stock using ultrapure water to create a 10 millimolar citric acid buffer for mRNA dilution.Next, make C 12 200 ionizable lipid, helper lipid, cholesterol and lipid anchored PEG or lipid PEG stock solutions by dissolving each lipid in 100%ethanol. Ensure the stock solutions are fully dissolved by heating and mixing them at 37 degrees Celsius. Combine the calculated volumes of the different lipid components in a conical tube.Dilute the lipids with 100%ethanol to final volume of V, which represents 25%of the final volume of LNP. Calculate the amount of mRNA required for formulation based on the ionizable lipid to mRNA weight ratio and the total volume of mRNA-LNP. Next, thaw the firefly luciferase encoding mRNA on ice.Then dilute the mRNA to a final volume three times the organic phase using the 10 millimolar citric acid buffer. Spray a delicate task wipe with a surface decontaminate for RNAs and DNA, and wipe the interior of the microfluidic instrument thoroughly. Next, open a new microfluidic cartridge and insert it with the inlet channels facing down and away.Arrange two sterile 15 milliliter conical tubes on the holder with the caps off. Once done, fill a five milliliter syringe with the mRNA solution containing mRNA diluted in 10 millimolar citric acid buffer. Then fill a three milliliter syringe with the lipid solution containing the lipids diluted in 100%ethanol.Ensure to remove any air from the syringes. Then without the needle, insert the five milliliter syringe containing the mRNA solution into the left inlet of the cartridge, and insert the three milliliter syringe containing the lipid solution into the right inlet of the cartridge. Turn on the microfluidic instrument and select quick run.After selecting the correct syringe types for the five and three milliliter syringes inserted, input the parameters for LNP formulation at a three to one aqueous to organic flow rate ratio, before pressing the start button to formulate the mRNA-LNPs. Load the mRNA-LNPs collected in the right conical tube into the previously hydrated dialysis cassettes using a syringe without puncturing or touching the cassette membrane, place the dialysis cassettes containing the mRNA-LNPs back into the beaker containing PBS and let them dialyze for at least two hours. After dialysis, bring the dialysis cassettes containing the mRNA-LNPs into a sterile biosafety cabinet and remove the mRNA-LNPs using a syringe with a needle.Sterile filter the mRNA-LNPs using a 0.22 micrometer syringe filter and collect them in a sterile conical tube. Then place 65 microliters of the mRNA-LNP solution into a 1.5 milliliter microtube for characterization. Plate 5, 000 HepG2 cells in a white wall, clear bottom, 96-well plate in 100 microliters of complete cell culture medium and incubate the cells overnight in a controlled incubator at 37 degrees Celsius containing 5%carbon dioxide.Before treatment of cells with mRNA-LNPs, remove the complete medium from the wells. Next, treat the cells with either 100 microliters of mRNA-LNPs diluted in complete cell culture medium at the desired doses, or 100 microliters of complete medium before a 24 hour incubation. After incubation, remove the cell culture medium from the 96-well plate, add 20 microliters of lysis buffer to each well followed by 100 microliters of the luciferase assay reagents.Protect the plate from light and place the plate into a plate reader to measure the bioluminescent signal. Dilute the mRNA-LNP solution using sterile PBS so that two micrograms of total mRNA is present in 100 microliters of the tail vein injection volume. Fill a 29 gauge insulin syringe with either 100 microliters of mRNA-LNP or 100 microliters of PBS and remove any bubbles from the syringe.Insert the needle with the bevel facing up into the mouse's lateral tail vein and slowly inject the 100 microliters of mRNA-LNP or PBS. Six hours post injection, prepare a 15 milligram per milliliter stock solution of D-Luciferin potassium salt in sterile PBS. In the imaging software for the in vivo imaging system, or IVIS, select the box next to luminescence before pressing initialize to prepare the instrument for data acquisition.Next, administer 200 microliters of D-Luciferin intraperitonealy to the previously treated mice and wait for 10 minutes while the luciferase signal stabilizes before anesthetizing the mice. Transfer the anesthetized mice to the nose cones inside the in vivo imaging system, ensuring that they're on their backs with their abdomens exposed, before closing the chamber door. In the imaging software, ensure that the correct field of view is selected and set the exposure time to auto, click the acquire button in the software to obtain bioluminescence images.The encapsulation efficiency of the mRNA-LNPs was determined as 92.3%using the modified fluorescence assay and equation shown here. Increasing bioluminescence was observed upon treatment of 5, 000 HepG2 cells with increasing doses of mRNA-LNP. Luciferase expression was easily detected at this study's lowest dose of five nanograms per well.A strong bioluminescence signal was observed in the upper abdomen of the mice treated with formulated LNPs. Regions of interest were drawn around the liver signals to calculate the total luminescent flux. The total luminescent flux was approximately five times 10 to the 9th.Always maintain the ionizable lipid to nucleic acid weight ratio when formulating LNPs. Every volume of the organic phase should contain ionizable lipid corresponding to mRNA in three volumes of the aqueous phase.

testing-vitro-vivo-efficiency-mrna-lipid-nanoparticles-formulated

Research

JoVE Journal

Bioengineering

Viral Nanoparticles for In vivo Tumor Imaging

The use of nanomaterials has the potential to revolutionize materials science and medicine. Currently, a number of different nanoparticles are being investigated for applications in imaging and therapy. Viral nanoparticles (VNPs) derived from plants can be regarded as self-assembled bionanomaterials with defined sizes and shapes. Plant viruses under investigation in the Steinmetz lab include icosahedral particles formed by Cowpea mosaic virus (CPMV) and Brome mosaic virus (BMV), both of which are 30 nm in diameter. We are also developing rod-shaped and filamentous structures derived from the following plant viruses: Tobacco mosaic virus (TMV), which forms rigid rods with dimensions of 300 nm by 18 nm, and Potato virus X (PVX), which form filamentous particles 515 nm in length and 13 nm in width (the reader is referred to refs. 1 and 2 for further information on VNPs).
From a materials scientist's point of view, VNPs are attractive building blocks for several reasons: the particles are monodisperse, can be produced with ease on large scale in planta, are exceptionally stable, and biocompatible. Also, VNPs are "programmable" units, which can be specifically engineered using genetic modification or chemical bioconjugation methods 3. The structure of VNPs is known to atomic resolution, and modifications can be carried out with spatial precision at the atomic level4, a level of control that cannot be achieved using synthetic nanomaterials with current state-of-the-art technologies.
In this paper, we describe the propagation of CPMV, PVX, TMV, and BMV in Vigna ungiuculata and Nicotiana benthamiana plants. Extraction and purification protocols for each VNP are given. Methods for characterization of purified and chemically-labeled VNPs are described. In this study, we focus on chemical labeling of VNPs with fluorophores (e.g. Alexa Fluor 647) and polyethylene glycol (PEG). The dyes facilitate tracking and detection of the VNPs 5-10, and PEG reduces immunogenicity of the proteinaceous nanoparticles while enhancing their pharmacokinetics 8,11. We demonstrate tumor homing of PEGylated VNPs using a mouse xenograft tumor model. A combination of fluorescence imaging of tissues ex vivo using Maestro Imaging System, fluorescence quantification in homogenized tissues, and confocal microscopy is used to study biodistribution. VNPs are cleared via the reticuloendothelial system (RES); tumor homing is achieved passively via the enhanced permeability and retention (EPR) effect12. The VNP nanotechnology is a powerful plug-and-play technology to image and treat sites of disease in vivo. We are further developing VNPs to carry drug cargos and clinically-relevant imaging moieties, as well as tissue-specific ligands to target molecular receptors overexpressed in cancer and cardiovascular disease.

Viral Nanoparticles for In vivo Tumor Imaging

Plant viral nanoparticles (VNPs) are promising platforms for applications in biomedicine. Here, we describe the procedures for plant VNP propagation, purification, characterization, and bioconjugation. Finally, we show the application of VNPs for tumor homing and imaging using a mouse xenograft model and fluorescence imaging.

The use of nanomaterials has the potential to revolutionize materials science and medicine. Currently, a number of different nanoparticles are being ...

Quantification of Global Diastolic Function by Kinematic Modeling-based Analysis of Transmitral Flow via the Parametrized Diastolic Filling Formalism

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised the only means available, the development of noninvasive imaging modalities (echocardiography, MRI, CT) having high temporal and spatial resolution provide a new window for quantitative diastolic function assessment. Echocardiography is the agreed upon standard for diastolic function assessment, but indexes in current clinical use merely utilize selected features of chamber dimension (M-mode) or blood/tissue motion (Doppler) waveforms without incorporating the physiologic causal determinants of the motion itself.&#160;The recognition that all left ventricles (LV) initiate filling by serving as mechanical suction pumps allows global diastolic function to be assessed based on laws of motion that apply to all chambers. What differentiates one heart from another are the parameters of the equation of motion that governs filling. Accordingly, development of the Parametrized Diastolic Filling (PDF) formalism&#160;has shown that the entire range of clinically observed early transmitral flow (Doppler E-wave) patterns are extremely well fit by the laws of damped oscillatory motion.&#160;This permits analysis of individual E-waves in accordance with a causal mechanism (recoil-initiated suction) that yields three (numerically) unique lumped parameters whose physiologic analogues are chamber stiffness (k), viscoelasticity/relaxation (c), and load (xo).&#160;The recording of transmitral flow (Doppler E-waves) is standard practice in clinical cardiology and, therefore, the echocardiographic recording method is only briefly reviewed. Our focus is on determination of the PDF parameters from routinely recorded E-wave data.&#160;As the highlighted results indicate, once the PDF parameters have been obtained from a suitable number of load varying E-waves, the investigator is free to use the parameters or construct indexes from the parameters (such as stored energy 1/2kxo2, maximum A-V pressure gradient kxo, load independent index of diastolic function, etc.) and select the aspect of physiology or pathophysiology to be quantified.

Accurate, causality-based quantification of global diastolic function has been achieved by kinematic modeling-based analysis of transmitral flow via the Parametrized Diastolic Filling (PDF) formalism. PDF generates unique stiffness, relaxation,&#160;and load parameters and elucidates &#39;new&#39; physiology while providing sensitive and specific indexes of dysfunction.

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians.&#160;Although historically invasive methods have comprised ...

Analyzing Mixing Inhomogeneity in a Microfluidic Device by Microscale Schlieren Technique

In this paper, we introduce the use of microscale schlieren technique to measure mixing inhomogeneity in a microfluidic device. The microscale schlieren system is constructed from a Hoffman modulation contrast microscope, which provides easy access to the rear focal plane of the objective lens, by removing the slit plate and replacing the modulator with a knife-edge. The working principle of microscale schlieren technique relies on detecting light deflection caused by variation of refractive index1-3. The deflected light either escapes or is obstructed by the knife-edge to produce a bright or a dark band, respectively. If the refractive index of the mixture varies linearly with its composition, the local change in light intensity in the image plane is proportional to the concentration gradient normal to the optical axis. The micro-schlieren image gives a two-dimensional projection of the disturbed light produced by three-dimensional inhomogeneity.
To accomplish quantitative analysis, we describe a calibration procedure that mixes two fluids in a T-microchannel. We carry out a numerical simulation to obtain the concentration gradient in the T-microchannel that correlates closely with the corresponding micro-schlieren image. By comparison, a relationship between the grayscale readouts of the micro-schlieren image and the concentration gradients presented in a microfluidic device is established. Using this relationship, we are able to analyze the mixing inhomogeneity from associate micro-schlieren image and demonstrate the capability of microscale schlieren technique with measurements in a microfluidic oscillator4. For optically transparent fluids, microscale schlieren technique is an attractive diagnostic tool to provide instantaneous full-field information that retains the three-dimensional features of the mixing process.

Herein, we describe a procedure that employs microscale schlieren technique to measure mixing inhomogeneity in a microfluidic device. Through calibration, distribution of concentration gradient can be derived from the micro-schlieren image.

In this paper, we introduce the use of microscale schlieren technique to measure mixing inhomogeneity in a microfluidic device. The microscale schlieren ...

Eye Irritation Test (EIT) for Hazard Identification of Eye Irritating Chemicals using Reconstructed Human Cornea-like Epithelial (RhCE) Tissue Model

To comply with the Seventh Amendment to the EU Cosmetics Directive and EU REACH legislation, validated non-animal alternative methods for reliable and accurate assessment of ocular toxicity in man are needed. To address this need, we have developed an eye irritation test (EIT) which utilizes a three dimensional reconstructed human cornea-like epithelial (RhCE) tissue model that is based on normal human cells. The EIT is able to separate ocular&#160;irritants and corrosives (GHS Categories 1 and 2 combined) and those that do not require labeling (GHS No Category). The test utilizes two separate protocols, one designed for liquid chemicals and a second, similar protocol for solid test articles. The EIT prediction model uses a single exposure period (30 min for liquids, 6 hr for solids) and a single tissue viability cut-off (60.0% as determined by the MTT assay). Based on the results for 83 chemicals (44 liquids and 39 solids) EIT achieved 95.5/68.2/ and 81.8% sensitivity/specificity and accuracy (SS&#38;A) for liquids, 100.0/68.4/ and 84.6% SS&#38;A for solids, and 97.6/68.3/ and 83.1% for overall SS&#38;A. The EIT will contribute significantly to classifying the ocular irritation potential of a wide range of liquid and solid chemicals without the use of animals to meet regulatory testing requirements. The EpiOcular EIT method was implemented in 2015 into the OECD Test Guidelines as TG 492.

Eye Irritation Test EIT for Hazard Identification of Eye Irritating Chemicals using Reconstructed Human Cornea-like Epithelial RhCE Tissue Model

We have developed an eye irritation test which utilizes a three dimensional reconstructed human cornea-like epithelial (RhCE) tissue model. The test is able to discriminate between ocular irritant and corrosive materials (GHS Categories 1 and 2 combined) and those that do not require labeling (GHS No Category).

To comply with the Seventh Amendment to the EU Cosmetics Directive and EU REACH legislation, validated non-animal alternative methods for reliable and ...

Layer-by-layer Collagen Deposition in Microfluidic Devices for Microtissue Stabilization

Although microfluidics provides exquisite control of the cellular microenvironment, culturing cells within microfluidic devices can be challenging. 3D culture of cells in collagen type I gels helps to stabilize cell morphology and function, which is necessary for creating microfluidic tissue models in microdevices. Translating traditional 3D culture techniques for tissue culture plates to microfluidic devices is often difficult because of the limited channel dimensions. In this method, we describe a technique for modifying native type I collagen to generate polycationic and polyanionic collagen solutions that can be used with layer-by-layer deposition to create ultrathin collagen assemblies on top of cells cultured in microfluidic devices. These thin collagen layers stabilize cell morphology and function, as shown using primary hepatocytes as an example cell, allowing for the long term culture of microtissues in microfluidic devices.

The creation of functional microtissues within microfluidic devices requires the stabilization of cell phenotypes by adapting traditional cell culture techniques to the limited spatial dimensions in microdevices. Modification of collagen allows the layer-by-layer deposition of ultrathin collagen assemblies that can stabilize primary cells, such as hepatocytes, as microfluidic tissue models.

Although microfluidics provides exquisite control of the cellular microenvironment, culturing cells within microfluidic devices can be challenging. 3D ...

Production of Metal Nanoparticles by Pulsed Laser-ablation in Liquids: A Tool for Studying the Antibacterial Properties of Nanoparticles

The emergence of multidrug-resistant bacteria is a global clinical concern leading some to speculate about our return to a "pre-antibiotics" era of medicine. In addition to efforts to identify novel small-molecule antimicrobial drugs, there has been great interest in the use of metal nanoparticles as coatings for medical devices, wound dressings, and consumer packaging, due to their antimicrobial properties. The wide variety of methods available for nanoparticle synthesis results in a broad spectrum of chemical and physical properties which can affect antibacterial efficacy. This manuscript describes the pulsed laser-ablation in liquids (PLAL) method to create nanoparticles. This approach allows for the fine tuning of nanoparticle size, composition, and stability using post-irradiation methods as well as the addition of surfactants or volume excluders. By controlling particle size and composition, a large range of physical and chemical properties of metal nanoparticles can be explored which may contribute to their antimicrobial efficacy thereby opening new avenues for antibacterial development.

The antimicrobial properties of metals such as copper and silver have been recognized for centuries. This protocol describes pulsed laser-ablation in liquids, a method of synthesizing metal nanoparticles that provides the ability to fine tune the properties of these nanoparticles to optimize their antimicrobial effects.

The emergence of multidrug-resistant bacteria is a global clinical concern leading some to speculate about our return to a "pre-antibiotics" era of ...

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and dampen loads in the spine. The IVD consists of a proteoglycan-rich nucleus pulposus (NP) and a collagen-rich annulus fibrosis (AF) sandwiched by cartilaginous end-plates. Together with the adjacent vertebrae, the vertebrae-IVD structure forms a functional spine unit (FSU). These microstructures contain unique cell types as well as unique extracellular matrices. Whole organ culture of the FSU preserves the native extracellular matrix, cell differentiation phenotypes, and cellular-matrix interactions. Thus, organ culture techniques are particularly useful for investigating the complex biological mechanisms of the IVD. Here, we describe a high-throughput approach for culturing whole lumbar mouse FSUs that provides an ideal platform for studying disease mechanisms and therapies for the IVD. Furthermore, we describe several applications that utilize this organ culture method to conduct further studies including contrast-enhanced microCT imaging and three-dimensional high-resolution finite element modeling of the IVD.

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Whole organ culture of the intervertebral disc (IVD) preserves the native extracellular matrix, cell phenotypes, and cellular-matrix interactions. Here we describe an IVD culture system using mouse lumbar and caudal IVDs in their functional spinal units and several applications utilizing this system.

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and ...

Rigid Embedding of Fixed and Stained, Whole, Millimeter-Scale Specimens for Section-free 3D Histology by Micro-Computed Tomography

For over a hundred years, the histological study of tissues has been the gold standard for medical diagnosis because histology allows all cell types in every tissue to be identified and characterized. Our laboratory is actively working to make technological advances in X-ray micro-computed tomography (micro-CT) that will bring the diagnostic power of histology to the study of full tissue volumes at cellular resolution (i.e., an X-ray Histo-tomography modality). Toward this end, we have made targeted improvements to the sample preparation pipeline. One key optimization, and the focus of the present work, is a straightforward method for rigid embedding of fixed and stained millimeter-scale samples. Many of the published methods for sample immobilization and correlative micro-CT imaging rely on placing the samples in paraffin wax, agarose, or liquids such as alcohol. Our approach extends this work with custom procedures and the design of a 3-dimensional printable apparatus to embed the samples in an acrylic resin directly into polyimide tubing, which is relatively transparent to X-rays. Herein, sample preparation procedures are described for the samples from 0.5 to 10 mm in diameter, which would be suitable for whole zebrafish larvae and juveniles, or other animals and tissue samples of similar dimensions. As proof of concept, we have embedded the specimens from Danio, Drosophila, Daphnia, and a mouse embryo; representative images from 3-dimensional scans for three of these samples are shown. Importantly, our methodology leads to multiple benefits including rigid immobilization, long-term preservation of laboriously-created resources, and the ability to re-interrogate samples.

We developed protocols and designed a custom apparatus to enable embedding of millimeter-scale specimens. We present sample preparation procedures with an emphasis on embedding in acrylic resin and polyimide tubing to achieve rigid immobilization and long-term storage of specimens for the interrogation of tissue architecture and cell morphology by micro-CT.

For over a hundred years, the histological study of tissues has been the gold standard for medical diagnosis because histology allows all cell types in ...

Catalytic Scavenging of Plant Reactive Oxygen Species In Vivo by Anionic Cerium Oxide Nanoparticles

Reactive oxygen species (ROS) accumulation is a hallmark of plant abiotic stress response. ROS play&#160;a dual role in plants by acting as signaling molecules at low levels and damaging molecules at high levels. Accumulation of ROS in stressed plants can damage metabolites, enzymes, lipids, and DNA, causing a reduction of plant growth and yield. The ability of cerium oxide nanoparticles (nanoceria) to catalytically scavenge ROS in vivo provides a unique tool to understand and bioengineer plant abiotic stress tolerance. Here, we present a protocol to synthesize and characterize poly (acrylic) acid coated nanoceria (PNC), interface the nanoparticles with plants via leaf lamina infiltration, and monitor their distribution and ROS scavenging in vivo using confocal microscopy. Current molecular tools for manipulating ROS accumulation in plants are limited to model species and require laborious transformation methods. This protocol for in vivo ROS scavenging has the potential to be applied to wild type plants with broad leaves and leaf structure like Arabidopsis thaliana.

Catalytic Scavenging of Plant Reactive Oxygen Species In Vivo by Anionic Cerium Oxide Nanoparticles

Here, we present a protocol for the synthesis and characterization of cerium oxide nanoparticles (nanoceria) for ROS (reactive oxygen species) scavenging in vivo, nanoceria imaging in plant tissues by confocal microscopy, and in vivo monitoring of nanoceria ROS scavenging by confocal microscopy.

Reactive oxygen species (ROS) accumulation is a hallmark of plant abiotic stress response. ROS play&#160;a dual role in plants by acting as signaling ...

Advanced 3D Liver Models for In vitro Genotoxicity Testing Following Long-Term Nanomaterial Exposure

Due to the rapid development and implementation of a diverse array of engineered nanomaterials (ENM), exposure to ENM is inevitable and the development of robust, predictive in vitro test systems is essential. Hepatic toxicology is key when considering ENM exposure, as the liver serves a vital role in metabolic homeostasis and detoxification as well as being a major site of ENM accumulation post exposure. Based upon this and the accepted understanding that 2D hepatocyte models do not accurately mimic the complexities of intricate multi-cellular interactions and metabolic activity observed in vivo, there is a greater focus on the development of physiologically relevant 3D liver models tailored for ENM hazard assessment purposes in vitro. In line with the principles of the 3Rs to replace, reduce and refine animal experimentation, a 3D HepG2 cell-line based liver model has been developed, which is a user friendly, cost effective system that can support both extended and repeated ENM exposure regimes (&#8804;14 days). These spheroid models (&#8805;500 &#181;m in diameter) retain their proliferative capacity (i.e., dividing cell models) allowing them to be coupled with the &#8216;gold standard&#8217; micronucleus assay to effectively assess genotoxicity in vitro. Their ability to report on a range of toxicological endpoints (e.g., liver function, (pro-)inflammatory response, cytotoxicity and genotoxicity) has been characterized using several ENMs across both acute (24 h) and long-term (120 h) exposure regimes. This 3D in vitro hepatic model has the capacity to be utilized for evaluating more realistic ENM exposures, thereby providing a future in vitro approach to better support ENM hazard assessment in a routine and easily accessible manner.

This procedure was established to be used for developing advanced 3D hepatic cultures in vitro, which can provide a more physiologically relevant assessment of the genotoxic hazards associated with nanomaterial exposures over both an acute or long-term, repeated dose regimes.

Due to the rapid development and implementation of a diverse array of engineered nanomaterials (ENM), exposure to ENM is inevitable and the development of ...