Name: lignin down-regulation of zea mays via dsrnai and klason lignin analysis
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Description: Watch this Scientific Journal Video about Lignin Down-regulation of Zea mays via dsRNAi and Klason Lignin Analysis at JoVE.com

The microscopic imaging was conducted via the services of the Michigan State University Center for Advanced Microscopy. Maize callus was purchased from the Maize Transformation Center of Iowa State University. The authors would like to thank Jeffrey R. Weatherhead of the MSU Plant Research Laboratory for his technical assistance on the carbohydrate analysis. This research was generously funded by the Corn Marketing Program of Michigan (CMPM) and the Consortium for Plant Biotechnology Research (CPBR).

1. Preparation of dsRNAi Constructs Used for the Down-regulation of ZmCCR1
<ol>
	<li>Design gene specific primers including necessary restriction enzyme sites for making a dsRNAi construct to knock-out the ZmCCR1 gene. Two primer sets were designed to amplify two fragment segments of ZmCCR1 cDNA: a 523 bp fragment from nucleotide 748 to 1271, and a 285 bp fragment from nucleotide 986 to 1271. The ZmCCR1 cDNA was provided from the Arizona Genome Institute (AGI). More details are descr...

<ol>
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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=Downregulation+of+Maize+Cinnamoyl-Coenzyme+A+Reductase+via+RNA+Interference+Technology+Causes+Brown+Midrib+and+Improves+Ammonia+Fiber+Expansion-Pretreated+Conversion+into+Fermentable+Sugars+for+Biofuels.">Downregulation of Maize Cinnamoyl-Coenzyme A Reductase via RNA Interference Technology Causes Brown Midrib and Improves Ammonia Fiber Expansion-Pretreated Conversion into Fermentable Sugars for Biofuels.</a> Crop Sci. 52, 2687-2701 (2012).</li><li>Altpeter, F., 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=Particle+bombardment+and+the+genetic+enhancement+of+crops:+myths+and+realities.">Particle bombardment and the genetic enhancement of crops: myths and realities.</a> Mol Breeding. 15, 305-327 (2005).</li><li>Pichon, M., Courbou, I., Beckert, M., Boudet, A. M., Grima-Pettenati, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cloning+and+characterization+of+two+maize+cDNAs+encoding+cinnamoyl-CoA+reductase+(CCR)+and+differential+expression+of+the+corresponding+genes.">Cloning and characterization of two maize cDNAs encoding cinnamoyl-CoA reductase (CCR) and differential expression of the corresponding genes.</a> Plant molecular biology. 38, 671-676 (1998).</li><li>Mansoor, S., Amin, I., Hussain, M., Zafar, Y., Briddon, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Engineering+novel+traits+in+plants+through+RNA+interference.">Engineering novel traits in plants through RNA interference.</a> Trends in plant science. 11, 559-565 (2006).</li><li>Hatfield, R. D., Jung, H. -. J. G., Ralph, J., Buxton, D. R., Weimer, P. 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Review and description of methods.</a> Journal of agricultural and food chemistry. 58, 9043-9053 (2010).</li><li>Sluiter, A., Hames, B., Ruiz, R., Scarlata, C., Sluiter, J., Templeton, D., Crocker, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+structural+carbohydrates+and+lignin+in+biomass.">Determination of structural carbohydrates and lignin in biomass.</a> Laboratory Analytic Procedure. , (2008).</li><li>Bate, N. 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The accessibility of microbial cellulases to plant cell wall polysaccharides is largely dependent on the degree to which they are associated with phenolic polymers23. The conversion rate from lignocellulosic biomass to fermentable sugar is negatively correlated with lignin content deposited in plant secondadry cell walls. This correlation is ascribed to the physical properties of lignin such as hydrophobicity24, chemical heterogeneity, and the absence of regular hydrolysable intermonomeric linkages<...

The production of biofuels from lignocellulosic biomass is highly desirable due to its present abundance in the U.S.1, and in the case of the sustainable harvest of agricultural and forestry residues, the ability to not compete directly for cropland used for food and animal feed production. However, unlike maize grain, which is the main source of biofuel currently generated in the U.S., lignocellulosic materials are significantly more complex and difficult to break down. In addition to the long-chain carbohydrates, cellulose and hemicellulose, which are the main sources of sugars during fermentation of lignocellulosic materials, many types of plant cell walls also contain lignin, a phenylpropanoid polymer that provides strength, defense against pathogen attack, and hydrophobicity to cell walls. While necessary for plant growth and survival, lignin also presents a significant barrier to the successful enzymatic conversion of the cellulose and hemicellulose to soluble sugars. Materials with high lignin contents are generally less desirable materials for both the biofuel (through biological conversion pathways) and the pulp and paper industries due to the negative impacts on processing characteristics and product quality. Hence, genetic manipulation of plant materials for lignin reduction at a level that does not interfere with crop structural strength and defense systems might be important for the reduction of production costs for both the lignocellulosic biofuel and the pulp and paper industries.
In maize (Zea mays), lignin is covalently cross-linked to hemicellulose in the primary cell wall via ferulate and diferulate bridges2. The lignin-hemicellulose complex binds to cellulose microfibrils through hydrogen bonds, forming a complex matrix that confers integrity and strength to the secondary cell wall. The mechanical strength of plant cell walls is largely determined by the type of lignin subunits3-5. In previous studies, altering the proportions of lignin subunits has shown no clear trend on enzymatic digestibility6-11. However, reductions in lignin content generally show an improvement in conversions12,13 and may be a key to increasing the digestibility of plant material by hydrolytic enzymes including endocellulases, cellobiohydrolases, and &#946;-glucosidases14.
Genetic engineering to regulate the expression level of transcripts has been extensively practiced to improve crop traits. Advanced techniques, including anti-sense15 and co-suppression16 technologies, enable effective down-regulation of target genes. Complete gene knock-out has also been achieved using gene constructs encoding intron-spliced RNA with a hairpin structure17. Furthermore, a double stranded RNA interference (dsRNAi) technique, i.e. a powerful and effective gene expression mediator that works by either targeting transcript degradation or translation repression, provides a potent means to induce a wide range of suppression effects on the target mRNA18. Gene silencing techniques show several limitations. These techniques do not precisely regulate the level of transcription and it could cause unexpected silencing effects on other homologous genes.
In this method, we employed particle bombardment to carry the dsRNAi constructs into the maize genome. To date, a vast array of plant species have been successfully transformed using particle bombardment, Agrobacterium mediated transformation, electroporation, and microinjection methods. In maize genetic transformation, the particle bombardment method is advantageous over all the other methods because it is the most efficient. Particle bombardment is not dependent on bacteria, so the method is free of biological constraints such as the size of the gene, species of gene origin, or the plant genotype. The physical transgene delivery system enables high molecular weight DNA and multiple genes to be introduced into plant genomes and in certain cases into chloroplasts at high transformation efficiency19. The lignin reduction in the vascular system of the leaf mid-rib can be visualized via scanning electron microscopy (SEM) which is beneficial for examining the topography and composition of samples.
In maize plants, two of the cinnamoyl-CoA reductase (ZmCCR1: X98083 and ZmCCR2: Y15069) genes were found in the maize genome20. Cinnamoyl-CoA reductase catalyzes the conversion of the hydroxycinnamoyl-CoA esters into cinnamyl aldehydes. We chose the ZmCCR1 gene to down-regulate this enzyme because the gene is expressed in all lignifying tissues. The 523 nucleotides at the 3&#8217; terminus of the ZmCCR1 gene were chosen for a dsRNAi construct because the sequences appeared to be more diverse as compared to those of ZmCCR2. Thus, the dsRNAi construct would precisely bind only to ZmCCR1, avoiding off-target silencing21. A ZmCCR1_RNAi construct was engineered into the cytoplasmic expression system ImpactVector1.1-tag (IV 1.1) containing the green tissue specific promoter, ribulose-1, 5-bisphosphate carboxylase oxygenase (RuBisCO).
To study the effects of the dsRNAi construct on transgenic plants, the lignin content was quantified. The Klason (acid-insoluble) lignin measurement is known to be more accurate compared to the acid detergent lignin quantification methods which solubilize some of the lignin22. Therefore, the Klason lignin was measured in transgenic maize stalks. This procedure consists of a two-step acid hydrolysis that converts polymeric carbohydrates into soluble monosaccharides23. The hydrolyzed biomass was then fractionated into acid soluble and insoluble materials and the acid insoluble lignin was measured according to previous studies23,24. Ideally, lignin analysis should include extractions with water and ethanol prior to the hydrolysis step, in order to remove soluble materials that can interfere with the results, and a post-hydrolysis combustion of the lignin residue to account for any ash present in the residue. Without these steps, the lignin content of the sample could be artificially inflated. The full method is presented here, however for our experiments we were unable to perform both of these steps due to the small volume of material available for testing
Two other cell wall components, cellulose and hemicellulose were also analyzed in the lignin down-regulated transgenic maize lines. It has been reported that transgenic plants that have been down-regulated in either their phenylalanine ammonia-lyase (PAL)25, 4-coumarate:CoA ligase (4CL)26, or cinnamyl alcohol dehydrogenase (CAD)27 show an increase in other cell wall structural components. As a first step in our studies, crystalline cellulose was measured using the Updegraff method28. This method was originally devised for determination of cellulose in a large number of cellulolytic bacteria and fungi. Briefly, the milled maize stocks were treated with Updegraff reagent (acetic acid: nitric acid: water) to remove hemicellulose, lignin, and xylosans. The crystalline cellulose was completely hydrolyzed into glucose via Saeman hydrolysis by adding H2SO4. The crystalline cellulose was then assayed using the colorimetric anthrone method29. To verify if the hemicellulose contents were changed, the monosaccharide extracts from milled stalks were hydrolyzed using trifluoroacetic acid, derivatized using the alditol acetate method and then analyzed by gas chromatography (GC)30. The detailed procedures for crystalline cellulose content and matrix polysaccharides composition analyses are described in Foster et al. (2010)31.
Here, we describe the procedures used for lignin down-regulation in maize via a RNAi technology, particle bombardment transformation, and lignin analysis for accelerated deconstruction of maize lignocellulosic biomass into fermentable sugars for biofuels.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Media</td>
			<td>Chemical compositions</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>N6OSM</td>
			<td>4 g/l N6 salts</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>(Osmotic medium)</td>
			<td>1 ml/l N6 vitamin stock</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>2 mg/l 2,4-D</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>100 mg/l myo-inositol</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>0.69 g/L proline</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>30 g/l sucrose</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>100 mg/L casein hydrolysate</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>36.4 g/l sorbitol</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>36.4 g/l mannitol</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>2.5g/l gelrite, pH 5.8</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Add filter sterilized silver nitrate (25uM) after autoclaving</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>N6E</td>
			<td>4 g/l N6 salts</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>(Callus induction)</td>
			<td>1 ml/l (1000X) N6 vitamin stock</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>2 mg/l 2,4-D</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>100 mg/l myo-inositol</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>2.76 g/l proline</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>30 g/l sucrose</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>100 mg/l casein hydrolysate</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>2.5g/l gelrite, pH 5.8.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Add filter sterilized silver nitrate (25uM) after autoclaving</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>N6S media</td>
			<td>4 g/l N6 salts</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>(Selection media)</td>
			<td>1 ml/l N6 vitamin stock</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>2 mg/l 2,4-D</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>100 mg/l myo-inositol</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>0.69 g/L proline</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>30 g/L sucrose</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>100 mg/L casein hydrolysate</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>36.4 g/l sorbitol</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>36.4 g/l mannitol</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>2.5g/l gelrite, pH 5.8</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Add filter sterilized silver nitrate (25uM) after autoclaving</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Regeneration medium</td>
			<td>4.3 g/L MS salts</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>1 ml/L (1000X) MS vitamin stock</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>100 mg/L myo-inositol</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>60 g/L sucrose</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>3 g/L gelrite, pH 5.8 (100x25 mm petri-plates)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Add filter sterilized bialaphos (3 mg/L) added after autoclaving.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Rooting medium</td>
			<td>4.3 g/L MS salts</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>1 ml/L MS vitamin stock</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>100 mg/L myo-inositol</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>30 g/L sucrose</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>3g/L gelrite, pH 5.8 (100x25 mm petri-plates).</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Specific materials</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Screw-top high pressure tubes</td>
			<td>Pressure tube (#8648-27); Ace Glass, Vineland, NJ</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Plug (#5845-47); Ace Glass, Vineland, NJ</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>10% Neutral buffered formalin&#160;</td>
			<td>100ml of formalin</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>(1 liter)</td>
			<td>900ml of ddH2O</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>4.0 g of Sodium dihydrogen phosphate, monohydrate&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>(NaH2PO4.H2O)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Equipments</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bio-Rad PSD-1000/He Particle Delivery device (Hercules, CA, United States)&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Zeiss PASCAL confocal laser scanning microscope (Carl Zeiss, Jena, Germany)&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Excelsior ES Tissue Processor (Thermo Scientific, Pittsburgh, PA, United States).</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>HistoCentre III Embedding Station (Thermo Scientific, Pittsburgh, PA, United States)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;Microtome Model Reichert 2030 (Reichert, Depew, NY, United States)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Emscope Sputter Coater model SC 500 (Ashford, Kent, England)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>JEOL JSM-6400V Scanning Electron Microscope (JEOL Ltd., Tokyo, Japan)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fitzpatrick JT-6 Homoloid mill; Continental Process Systems, Inc., Westmont, IL</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MA35 Moisture Analyzer; Sartorius</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Critical point dryer, Balzers CPD (Leica Microsysstems Inc, Buffalo Grove, IL, United States)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

lignin down-regulation of zea mays via dsrnai and klason lignin analysis

To facilitate the use of lignocellulosic biomass as an alternative bioenergy resource, during biological conversion processes, a pretreatment step is needed to open up the structure of the plant cell wall, increasing the accessibility of the cell wall carbohydrates. Lignin, a polyphenolic material present in many cell wall types, is known to be a significant hindrance to enzyme access. Reduction in lignin content to a level that does not interfere with the structural integrity and defense system of the plant might be a valuable step to reduce the costs of bioethanol production. In this study, we have genetically down-regulated one of the lignin biosynthesis-related genes, cinnamoyl-CoA reductase (ZmCCR1) via a double stranded RNA interference technique. The ZmCCR1_RNAi construct was integrated into the maize genome using the particle bombardment method. Transgenic maize plants grew normally as compared to the wild-type control plants without interfering with biomass growth or defense mechanisms, with the exception of displaying of brown-coloration in transgenic plants leaf mid-ribs, husks, and stems. The microscopic analyses, in conjunction with the histological assay, revealed that the leaf sclerenchyma fibers were thinned but the structure and size of other major vascular system components was not altered. The lignin content in the transgenic maize was reduced by 7-8.7%, the crystalline cellulose content was increased in response to lignin reduction, and hemicelluloses remained unchanged. The analyses may indicate that carbon flow might have been shifted from lignin biosynthesis to cellulose biosynthesis. This article delineates the procedures used to down-regulate the lignin content in maize via RNAi technology, and the cell wall compositional analyses used to verify the effect of the modifications on the cell wall structure.

We have demonstrated a reduction in the lignin content in maize plants via RNAi. The particle bombardment transformation method yielded around 30% trnasformation efficiency. The gene silencing of ZmCCR1 was consistently observed in T0-T2 generations. The lignin reduced transgenics grew similarly to wildtype maize plants except for displaying brown coloration in the leaf mid-rib, husk, and stem. The histological assay has shown that the mutant lines exhibit a significant reduction in the cell wall thickness of th...

Watch this Scientific Journal Video about Lignin Down-regulation of Zea mays via dsRNAi and Klason Lignin Analysis at JoVE.com

Lignin Down-regulation of Zea mays via dsRNAi and Klason Lignin Analysis

A double stranded RNA interference (dsRNAi) technique is employed to down-regulate the maize cinnamoyl coenzyme A reductase (ZmCCR1) gene to lower plant lignin content. Lignin down-regulation from the cell wall is visualized by microscopic analyses and quantified by the Klason method. Compositional changes in hemicellulose and crystalline cellulose are analyzed.

Lignin Down-regulation of Zea mays via dsRNAi and Klason Lignin Analysis

To facilitate the use of lignocellulosic biomass as an alternative bioenergy resource, during biological conversion processes, a pretreatment step is ...

lignin-down-regulation-zea-mays-via-dsrnai-klason-lignin

Research

JoVE Journal

Bioengineering

Contrast Ultrasound Targeted Treatment of Gliomas in Mice via Drug-Bearing Nanoparticle Delivery and Microvascular Ablation

We are developing minimally-invasive contrast agent microbubble based therapeutic approaches in which the permeabilization and/or ablation of the microvasculature are controlled by varying ultrasound pulsing parameters.  Specifically, we are testing whether such approaches may be used to treat malignant brain tumors through drug delivery and microvascular ablation.  Preliminary studies have been performed to determine whether targeted drug-bearing nanoparticle delivery can be facilitated by the ultrasound mediated destruction of "composite" delivery agents comprised of 100nm poly(lactide-co-glycolide) (PLAGA) nanoparticles that are adhered to albumin shelled microbubbles. We denote these agents as microbubble-nanoparticle composite agents (MNCAs). When targeted to subcutaneous C6 gliomas with ultrasound, we observed an immediate 4.6-fold increase in nanoparticle delivery in MNCA treated tumors over tumors treated with microbubbles co-administered with nanoparticles and a 8.5 fold increase over non-treated tumors. Furthermore, in many cancer applications, we believe it may be desirable to perform targeted drug delivery in conjunction with ablation of the tumor microcirculation, which will lead to tumor hypoxia and apoptosis. To this end, we have tested the efficacy of non-theramal cavitation-induced microvascular ablation, showing that this approach elicits tumor perfusion reduction, apoptosis, significant growth inhibition, and necrosis. Taken together, these results indicate that our ultrasound-targeted approach has the potential to increase therapeutic efficiency by creating tumor necrosis through microvascular ablation and/or simultaneously enhancing the drug payload in gliomas.

Insonation of microbubbles is a promising strategy for tumor ablation at reduced time-averaged acoustic powers, as well as for the targeted delivery of therapeutics. The purpose of the present study is to develop low duty cycle ultrasound pulsing strategies and nanocarriers to maximize non-thermal microvascular ablation and payload delivery to subcutaneous C6 gliomas.

We are developing minimally-invasive contrast agent microbubble based therapeutic approaches in which the permeabilization and/or ablation of the ...

Polymer Microarrays for High Throughput Discovery of Biomaterials

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a combinatorial library of materials to be screened in a parallel, high throughput format1. Herein is described the formation and characterization of a polymer microarray using an on-chip photopolymerization technique 2. This involves mixing monomers at varied ratios to produce a library of monomer solutions, transferring the solution to a glass slide format using a robotic printing device and curing with UV irradiation. This format is readily amenable to many biological assays, including stem cell attachment and proliferation, cell sorting and low bacterial adhesion, allowing the ready identification of 'hit' materials that fulfill a specific biological criterion3-5. Furthermore, the use of high throughput surface characterization (HTSC) allows the biological performance to be correlated with physio-chemical properties, hence elucidating the biological-material interaction6. HTSC makes use of water contact angle (WCA) measurements, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In particular, ToF-SIMS provides a chemically rich analysis of the sample that can be used to correlate the cell response with a molecular moiety. In some cases, the biological performance can be predicted from the ToF-SIMS spectra, demonstrating the chemical dependence of a biological-material interaction, and informing the development of hit materials5,3.

A description of the formation of a polymer microarray using an on-chip photopolymerization technique. The high throughput surface characterization using atomic force microscopy, water contact angle measurements, X-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry and a cell attachment assay is also described.

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a ...

Self-reporting Scaffolds for 3-Dimensional Cell Culture

Culturing cells in 3D on appropriate scaffolds is thought to better mimic the in vivo microenvironment and increase cell-cell interactions. The resulting 3D cellular construct can often be more relevant to studying the molecular events and cell-cell interactions than similar experiments studied in 2D. To create effective 3D cultures with high cell viability throughout the scaffold the culture conditions such as oxygen and pH need to be carefully controlled as gradients in analyte concentration can exist throughout the 3D construct. Here we describe the methods of preparing biocompatible pH responsive sol-gel nanosensors and their incorporation into poly(lactic-co-glycolic acid) (PLGA) electrospun scaffolds along with their subsequent preparation for the culture of mammalian cells. The pH responsive scaffolds can be used as tools to determine microenvironmental pH within a 3D cellular construct. Furthermore, we detail the delivery of pH responsive nanosensors to the intracellular environment of mammalian cells whose growth was supported by electrospun PLGA scaffolds. The cytoplasmic location of the pH responsive nanosensors can be utilized to monitor intracellular pH (pHi) during ongoing experimentation.

Biocompatible pH responsive sol-gel nanosensors can be incorporated into poly(lactic-co-glycolic acid) (PLGA) electrospun scaffolds. The produced self-reporting scaffolds can be used for in&#160;situ monitoring of microenvironmental conditions whilst culturing cells upon the scaffold. This is beneficial as the 3D cellular construct can be monitored in real-time without disturbing the experiment.

Culturing cells in 3D on appropriate scaffolds is thought to better mimic the in vivo microenvironment and increase cell-cell interactions. The resulting ...

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 ...

Studying Soft-matter and Biological Systems over a Wide Length-scale from Nanometer and Micrometer Sizes at the Small-angle Neutron Diffractometer KWS-2

The KWS-2 SANS diffractometer is dedicated to the investigation of soft matter and biophysical systems covering a wide length scale, from nm to &#181;m. The instrument is optimized for the exploration of the wide momentum transfer Q range between 1x10-4 and 0.5 &#197;-1 by combining classical pinhole, focusing (with lenses), and time-of-flight (with chopper) methods, while simultaneously providing high-neutron intensities with an adjustable resolution. Because of its ability to adjust the intensity and the resolution within wide limits during the experiment, combined with the possibility to equip specific sample environments and ancillary devices, the KWS-2 shows a high versatility in addressing the broad range of structural and morphological studies in the field. Equilibrium structures can be studied in static measurements, while dynamic and kinetic processes can be investigated over time scales between minutes to tens of milliseconds with time-resolved approaches. Typical systems that are investigated with the KWS-2 cover the range from complex, hierarchical systems that exhibit multiple structural levels (e.g., gels, networks, or macro-aggregates) to small and poorly-scattering systems (e.g., single polymers or proteins in solution). The recent upgrade of the detection system, which enables the detection of count rates in the MHz range, opens new opportunities to study even very small biological morphologies in buffer solution with weak scattering signals close to the buffer scattering level at high Q.
In this paper, we provide a protocol to investigate samples with characteristic size levels spanning a wide length scale and exhibiting ordering in the mesoscale structure using KWS-2. We present in detail how to use the multiple working modes that are offered by the instrument and the level of performance that is achieved.

Here, we present a protocol to investigate soft matter and biophysical systems over a wide mesoscopic length scale, from nm to &#181;m that involves the use of the KWS-2 SANS diffractometer at high intensities and an adjustable resolution.

The KWS-2 SANS diffractometer is dedicated to the investigation of soft matter and biophysical systems covering a wide length scale, from nm to &#181;m. ...

Mammalian Cell Division in 3D Matrices via Quantitative Confocal Reflection Microscopy

The study of how mammalian cell division is regulated in a 3D environment remains largely unexplored despite its physiological relevance and therapeutic significance. Possible reasons for the lack of exploration are the experimental limitations and technical challenges that render the study of cell division in 3D culture inefficient. Here, we describe an imaging-based method to efficiently study mammalian cell division and cell-matrix interactions in 3D collagen matrices. Cells labeled with fluorescent H2B are synchronized using the combination of thymidine blocking and nocodazole treatment, followed by a mechanical shake-off technique. Synchronized cells are then embedded into a 3D collagen matrix. Cell division is monitored using live-cell microscopy. The deformation of collagen fibers during and after cell division, which is an indicator of cell-matrix interaction, can be monitored and quantified using quantitative confocal reflection microscopy. The method provides an efficient and general approach to study mammalian cell division and cell-matrix interactions in a physiologically relevant 3D environment. This approach not only provides novel insights into the molecular basis of the development of normal tissue and diseases, but also allows for the design of novel diagnostic and therapeutic approaches.

This protocol efficiently studies mammalian cell division in 3D collagen matrices by integrating synchronization of cell division, monitoring of division events in 3D matrices using live-cell imaging technique, time-resolved confocal reflection microscopy and quantitative imaging analysis.

The study of how mammalian cell division is regulated in a 3D environment remains largely unexplored despite its physiological relevance and therapeutic ...

Rapid, Scalable Assembly and Loading of Bioactive Proteins and Immunostimulants into Diverse Synthetic Nanocarriers Via Flash Nanoprecipitation

Nanomaterials present a wide range of options to customize the controlled delivery of single and combined molecular payloads for therapeutic and imaging applications. This increased specificity can have significant clinical implications, including decreased side effects and lower dosages with higher potency. Furthermore, the in situ targeting and controlled modulation of specific cell subsets can enhance in vitro and in vivo investigations of basic biological phenomena and probe cell function. Unfortunately, the required expertise in nanoscale science, chemistry and engineering often prohibit laboratories without experience in these fields from fabricating and customizing nanomaterials as tools for their investigations or vehicles for their therapeutic strategies. Here, we provide protocols for the synthesis and scalable assembly of a versatile non-toxic block copolymer system amenable to the facile formation and loading of nanoscale vehicles for biomedical applications. Flash nanoprecipitation is presented as a methodology for rapid fabrication of diverse nanocarriers from poly(ethylene glycol)-bl-poly(propylene sulfide) copolymers. These protocols will allow laboratories with a wide range of expertise and resources to easily and reproducibly fabricate advanced nanocarrier delivery systems for their applications. The design and construction of an automated instrument that employs a high-speed syringe pump to facilitate the flash nanoprecipitation process and to allow enhanced control over the homogeneity, size, morphology and loading of polymersome nanocarriers is described.

Nanomaterials provide versatile mechanisms of controlled therapeutic delivery for both basic science and translational applications, but their fabrication often requires expertise that is unavailable in most biomedical laboratories. Here, we present protocols for the scalable fabrication and therapeutic loading of diverse self-assembled nanocarriers using flash nanoprecipitation.

Nanomaterials present a wide range of options to customize the controlled delivery of single and combined molecular payloads for therapeutic and imaging ...

Substructure Analyzer: A User-Friendly Workflow for Rapid Exploration and Accurate Analysis of Cellular Bodies in Fluorescence Microscopy Images

The last decade has been characterized by breakthroughs in fluorescence microscopy techniques illustrated by spatial resolution improvement but also in live-cell imaging and high-throughput microscopy techniques. This led to a constant increase in the amount and complexity of the microscopy data for a single experiment. Because manual analysis of microscopy data is very time consuming, subjective, and prohibits quantitative analyses, automation of bioimage analysis is becoming almost unavoidable. We built an informatics workflow called Substructure Analyzer to fully automate signal analysis in bioimages from fluorescent microscopy. This workflow is developed on the user-friendly open-source platform Icy and is completed by functionalities from ImageJ. It includes the pre-processing of images to improve the signal to noise ratio, the individual segmentation of cells (detection of cell boundaries) and the detection/quantification of cell bodies enriched in specific cell compartments. The main advantage of this workflow is to propose complex bio-imaging functionalities to users without image analysis expertise through a user-friendly interface. Moreover, it is highly modular and adapted to several issues from the characterization of nuclear/cytoplasmic translocation to the comparative analysis of different cell bodies in different cellular sub-structures. The functionality of this workflow is illustrated through the study of the Cajal (coiled) Bodies under oxidative stress (OS) conditions. Data from fluorescence microscopy show that their integrity in human cells is impacted a few hours after the induction of OS. This effect is characterized by a decrease of coilin nucleation into characteristic Cajal Bodies, associated with a nucleoplasmic redistribution of coilin into an increased number of smaller foci. The central role of coilin in the exchange between CB components and the surrounding nucleoplasm suggests that OS induced redistribution of coilin could affect the composition and the functionality of Cajal Bodies.

We present a freely available workflow built for rapid exploration and accurate analysis of cellular bodies in specific cell compartments in fluorescence microscopy images. This user-friendly workflow is designed on the open-source software Icy and also uses ImageJ functionalities. The pipeline is affordable without knowledge in image analysis.

The last decade has been characterized by breakthroughs in fluorescence microscopy techniques illustrated by spatial resolution improvement but also in ...

Electric and Magnetic Field Devices for Stimulation of Biological Tissues

Electric fields (EFs) and magnetic fields (MFs) have been widely used by tissue engineering to improve cell dynamics such as proliferation, migration, differentiation, morphology, and molecular synthesis. However, variables such stimuli strength and stimulation times need to be considered when stimulating either cells, tissues or scaffolds. Given that EFs and MFs vary according to cellular response, it remains unclear how to build devices that generate adequate biophysical stimuli to stimulate biological samples. In fact, there is a lack of evidence regarding the calculation and distribution when biophysical stimuli are applied. This protocol is focused on the design and manufacture of devices to generate EFs and MFs and implementation of a computational methodology to predict biophysical stimuli distribution inside and outside of biological samples. The EF device was composed of two parallel stainless-steel electrodes located at the top and bottom of biological cultures. Electrodes were connected to an oscillator to generate voltages (50, 100, 150 and 200 Vp-p) at 60 kHz. The MF device was composed of a coil, which was energized with a transformer to generate a current (1 A) and voltage (6 V) at 60 Hz. A polymethyl methacrylate support was built to locate the biological cultures in the middle of the coil. The computational simulation elucidated the homogeneous distribution of EFs and MFs inside and outside of biological tissues. This computational model is a promising tool that can modify parameters such as voltages, frequencies, tissue morphologies, well plate types, electrodes and coil size to estimate the EFs and MFs to achieve a cellular response.

This protocol describes the step-by-step process to build both electrical and magnetic stimulators used to stimulate biological tissues. The protocol includes a guideline to simulate computationally electric and magnetic fields and manufacture of stimulator devices.

Electric fields (EFs) and magnetic fields (MFs) have been widely used by tissue engineering to improve cell dynamics such as proliferation, migration, ...

Inactivation of Pathogens via Visible-Light Photolysis of Riboflavin-5&#8242;-Phosphate

Riboflavin-5&#39;-phosphate (or flavin mononucleotide; FMN) is sensitive to visible light. Various compounds, including reactive oxygen species (ROS), can be generated from FMN photolysis upon irradiation with visible light. The ROS generated from FMN photolysis are harmful to microorganisms, including pathogenic bacteria such as Staphylococcus aureus (S. aureus). This article presents a protocol for deactivating S. aureus, as an example, via photochemical reactions involving FMN under visible light irradiation. The superoxide radical anion (<img alt="Equation 1" src="/files/ftp_upload/63531/63531eq01v3.png" style="margin: auto;" />) generated during the FMN photolysis is evaluated via nitro blue tetrazolium (NBT) reduction. The microbial viability of S. aureus that is attributed to reactive <img alt="Equation 1" src="/files/ftp_upload/63531/63531eq01v3.png" style="margin: auto;" /> species was used to determine the effectiveness of the process. The bacterial inactivation rate is proportional to FMN concentration. Violet light is more efficient in inactivating S. aureus than blue light irradiation, while the red or green light does not drive FMN photolysis. The present article demonstrates FMN photolysis as a simple and safe method for sanitary processes.

Inactivation of Pathogens via Visible-Light Photolysis of Riboflavin-5&amp;#8242;-Phosphate

Here, we present a protocol to inactivate pathogenic bacteria with reactive oxygen species produced during photolysis of flavin mononucleotide (FMN) under blue and violet light irradiation of low intensity. FMN photolysis is demonstrated to be a simple and safe method for sanitary processes.

Riboflavin-5&#39;-phosphate (or flavin mononucleotide; FMN) is sensitive to visible light. Various compounds, including reactive oxygen species (ROS), can ...