Name: polyethyleneimine-coated iron oxide nanoparticles as a vehicle for the delivery of small interfering rna to macrophages in vitro and in vivo
Uploaded: 2019-02-05T13:00:00
Description: Watch this Scientific Journal Video about Polyethyleneimine-coated Iron Oxide Nanoparticles as a Vehicle for the Delivery of Small Interfering RNA to Macrophages In Vitro and In Vivo at JoVE.com

This work was supported by the National Natural Science Foundation of China (81772308) and the National Key Research and Development Program of China (No. 2017YFA0205502).

All methods involving live animals were performed in accordance with the animal care and use guidelines of Southeast University, China.
1. Preparation of PEI-SPIONs
<ol>
	<li>Preparation of oleic acid-modified SPIONs
	<ol>
		<li>Dissolve FeCl3&#8226;6H2O and FeSO4&#8226;7H2O in water under the protection of N2.
		<ol>
			<li>Add 28 g of FeCl3&#8226;6H2O and 20 g of FeSO4&#8226;7H2</s...

<ol>
	<li>Murray, P. J., Wynn, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protective+and+pathogenic+functions+of+macrophage+subsets.">Protective and pathogenic functions of macrophage subsets.</a> Nature Reviews Immunology. 11 (11), 723 (2011).</li><li>Mae&#223;, M. B., Wittig, B., Lorkowski, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+efficient+transfection+of+human+THP-1+macrophages+by+nucleofection.">Highly efficient transfection of human THP-1 macrophages by nucleofection.</a> Journal of Visualized Experiments. (91), e51960 (2014).</li><li>Zhang, X., Edwards, J. P., Mosser, D. 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Y., Hogg, M. G., Dordick, J. S., Sharfstein, S. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+delivery+in+three-dimensional+cell+cultures+by+superparamagnetic+nanoparticles.">Gene delivery in three-dimensional cell cultures by superparamagnetic nanoparticles.</a> ACS Nano. 4 (8), 4733-4743 (2010).</li><li>Moghimi, S. M., Hunter, A. C., Murray, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-circulating+and+target-specific+nanoparticles:+theory+to+practice.">Long-circulating and target-specific nanoparticles: theory to practice.</a> Pharmacological Reviews. 53 (2), 283-318 (2001).</li><li>Harvey, A. E., Smart, J. A., Amis, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+spectrophotometric+determination+of+iron+(II)+and+total+iron+with+1,+10-phenanthroline.">Simultaneous spectrophotometric determination of iron (II) and total iron with 1, 10-phenanthroline.</a> Analytical Chemistry. 27 (1), 26-29 (1955).</li><li>Duan, J., 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=Polyethyleneimine-functionalized+iron+oxide+nanoparticles+for+systemic+siRNA+delivery+in+experimental+arthritis.">Polyethyleneimine-functionalized iron oxide nanoparticles for systemic siRNA delivery in experimental arthritis.</a> Nanomedicine. 9 (6), 789-801 (2014).</li><li>Fr&#246;hlich, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+surface+charge+in+cellular+uptake+and+cytotoxicity+of+medical+nanoparticles.">The role of surface charge in cellular uptake and cytotoxicity of medical nanoparticles.</a> International Journal of Nanomedicine. 7, 5577 (2012).</li><li>Wu, Y., 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=Ultra-small+particles+of+iron+oxide+as+peroxidase+for+immunohistochemical+detection.">Ultra-small particles of iron oxide as peroxidase for immunohistochemical detection.</a> Nanotechnology. 22 (22), 225703 (2011).</li><li>Xia, T., 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=Polyethyleneimine+coating+enhances+the+cellular+uptake+of+mesoporous+silica+nanoparticles+and+allows+safe+delivery+of+siRNA+and+DNA+constructs.">Polyethyleneimine coating enhances the cellular uptake of mesoporous silica nanoparticles and allows safe delivery of siRNA and DNA constructs.</a> ACS Nano. 3 (10), 3273-3286 (2009).</li><li>Mocellin, S., Provenzano, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+interference:+learning+gene+knock-down+from+cell+physiology.">RNA interference: learning gene knock-down from cell physiology.</a> Journal of Translational Medicine. 2 (1), 39 (2004).</li><li>Courties, G., 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=et+al.In+vivo+RNAi-mediated+silencing+of+TAK1+decreases+inflammatory+Th1+and+Th17+cells+through+targeting+of+myeloid+cells.">et al.In vivo RNAi-mediated silencing of TAK1 decreases inflammatory Th1 and Th17 cells through targeting of myeloid cells.</a> Blood. 116 (18), 3505-3516 (2010).</li><li>Zolnik, B. S., Gonzalez-Fernandez, A., Sadrieh, N., Dobrovolskaia, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Minireview:+nanoparticles+and+the+immune+system.">Minireview: nanoparticles and the immune system.</a> Endocrinology. 151 (2), 458-465 (2010).</li><li>Mulens-Arias, V., Rojas, J. M., P&#233;rez-Yag&#252;e, S., Morales, M. P., Barber, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polyethylenimine-coated+SPIONs+trigger+macrophage+activation+through+TLR-4+signaling+and+ROS+production+and+modulate+podosome+dynamics.">Polyethylenimine-coated SPIONs trigger macrophage activation through TLR-4 signaling and ROS production and modulate podosome dynamics.</a> Biomaterials. 52, 494-506 (2015).</li></ol>

Macrophages are refractory to transfect by commonly used nonviral approaches, such as electroporation, cationic liposomes, and lipid species. Here we described a reliable and efficient method to transfect macrophages with siRNA. Using the present protocol, over 90% of macrophage-like RAW 264.7 cells (Figure 2B)&#160;and rat peritoneal macrophages18 can be transfected with siRNA without significant impairment of the cell viability. This method depends on the delivery p...

Macrophages are a type of innate immune cells distributed in all body tissues, albeit in different amounts. By producing a variety of cytokines and other mediators, they play critical roles in the host defense against invading microbial pathogens, in tissue repair following injury, and in maintaining tissue homeostasis1. Due to their importance, macrophages have continuously been the subject of intensive research. However, despite its prevalence in gene regulation and function studies, siRNA-mediated gene silencing is less likely to succeed in macrophages because these cells&#8212;particularly, primary macrophages&#8212;are often difficult to transfect. This can be ascribed to a relatively high degree of toxicity associated with most well-established transfection approaches in which the cell membrane is chemically (e.g., with polymers and lipids) or physically (e.g., by electroporation and gene guns) disrupted to let siRNA molecules cross the membrane, thereby drastically reducing macrophages&#39; viability2,3. Furthermore, macrophages are dedicated phagocytes rich in degradative enzymes. These enzymes can damage the integrity of siRNA, weakening its silencing efficiency even if gene-specific siRNA has been delivered into the cell3,4. Therefore, an effective macrophage-targeted siRNA delivery system needs to protect the integrity and stability of siRNA during delivery4.
It is increasingly evident that dysfunctional macrophages are implicated in the initiation and progression of certain common clinical disorders like autoimmune diseases, atherosclerosis, and cancer. For this reason, modulating macrophage function with, for instance, siRNA, has been emerging as an attractive methodology for treating these disorders5,6,7. Although much progress has been made, a major challenge of siRNA-based treatment strategy is the poor cell specificity of systemically administered siRNA and the insufficient siRNA uptake by macrophages, which consequently lead to undesired side effects. Compared with free nucleic acid therapeutics that usually lack optimal cell selectivity and often lead to off-target adverse effects, drug-loaded nanoparticles (NPs), owing to their spontaneous propensity of being captured by the reticuloendothelial system, can be engineered for passive targeting to macrophages in vivo, allowing for improved therapeutic efficacy with minimal side effects8. Current NPs explored for the delivery of RNA molecules include inorganic nanocarriers, various liposomes, and polymers9. Among them, polyethyleneimine (PEI), a type of cationic polymers capable of binding and condensing nucleic acids into stabilized NPs, shows the highest RNA delivering capacity9,10. PEI protects nucleic acids from enzymatic and nonenzymatic degradation, mediates their transfer across the cell membrane, and promotes their intracellular release. Although initially introduced as a DNA delivery reagent, PEI was subsequently demonstrated to be an attractive platform for in vivo siRNA delivery, either locally or systemically9,10.
Superparamagnetic iron oxide nanoparticles (SPIONs) have shown great promise in biomedicine, owing to their magnetic properties, biocompatibility, comparable size to biologically important objects, high surface-area-to-volume ratio, and easily adaptable surface for bioagent attachment11. For instance, because of their potential utility as a contrast agent and rapid uptake by macrophages, SPIONs have emerged as a favorite clinical tool to image tissue macrophages12. While SPIONs have also been extensively studied as nucleic acid delivery vehicles11,13,14,15, to our knowledge, the literature contains few reports of SPIONs as a carrier for macrophage-targeted siRNA delivery. For gene delivery by SPIONs, their surface is usually coated with a layer of hydrophilic cationic polymers onto which negatively charged nucleic acids can be electrostatically attracted and tethered. Here, we present a method for synthesizing SPIONs whose surface is modified with low-molecular-weight (10 kDa), branched PEI (PEI-SPIONs). These magnetic nanoplatforms are then employed to condense siRNA, forming PEI-SPION/siRNA complexes that enable siRNA transport into the cell. We reason that spontaneous phagocytosis of SPIONs by cells of the reticuloendothelial system16, coupled with the strong ability of binding and condensing nucleic acids by PEI, renders PEI-SPIONs suitable for the efficient transport of siRNA into macrophages. The data presented here support the feasibility of PEI-SPION/siRNA-mediated gene silencing in macrophages in culture as well as in vivo.

<table>
	<tbody>
		<tr>
			<td>DMEM</td>
			<td>Gibco</td>
			<td>C11995500BT</td>
			<td>Warm in 37&#176;C water bath before use</td>
		</tr>
		<tr>
			<td>Fetal bovine serum</td>
			<td>Gibco</td>
			<td>A31608-02</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin/streptomycin (1.5 ml)</td>
			<td>Gibco</td>
			<td>15140122</td>
			<td></td>
		</tr>
		<tr>
			<td>Tetrazolium-based MTS assay kit</td>
			<td>Promega</td>
			<td>G3582</td>
			<td>For cytotoxicity analysis</td>
		</tr>
		<tr>
			<td>RAW 264.7 cell line</td>
			<td>Cell Bank of Chinese Academy of Sciences, Shanghai, China</td>
			<td>TCM13</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue culture plates (6-well)</td>
			<td>Corning</td>
			<td>3516</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue culture dishes (10 cm)</td>
			<td>Corning</td>
			<td>430167</td>
			<td></td>
		</tr>
		<tr>
			<td>RNase-free tubes (1.5 ml)</td>
			<td>AXYGEN</td>
			<td>MCT-150-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge tubes (15 ml)</td>
			<td>Corning</td>
			<td>430791</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin</td>
			<td>Gibco</td>
			<td>25200-056</td>
			<td></td>
		</tr>
		<tr>
			<td>Wistar rats</td>
			<td>Shanghai Experimental Animal Center of Chinese 
			Academy of Sciences</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bacillus Calmette&#8211;Gu&#233;rin freeze-dried powder</td>
			<td>National 
			Institutes for Food and Drug Control, China</td>
			<td></td>
			<td>for inducing adjuvant arthritis in rats</td>
		</tr>
		<tr>
			<td>siRNA</td>
			<td>GenePharma (Shanghai, China)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Cy3-siRNA</td>
			<td>RiboBio (Guangzhou, China)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Polyethyleneimine (10 kDa)</td>
			<td>Aladdin Chemical Reagent Co., Ltd.</td>
			<td>E107079</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonia water</td>
			<td>Aladdin Chemical Reagent Co., Ltd.</td>
			<td>A112077</td>
			<td></td>
		</tr>
		<tr>
			<td>Oleic acid</td>
			<td>Aladdin Chemical Reagent Co., Ltd.</td>
			<td>O108484</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethylsulfoxide</td>
			<td>Aladdin Chemical Reagent Co., Ltd.</td>
			<td>D103272</td>
			<td></td>
		</tr>
		<tr>
			<td>FeSO4&#8226;7H2O</td>
			<td>Sinopharm Chemical Reagent Co., Ltd</td>
			<td>10012118</td>
			<td></td>
		</tr>
		<tr>
			<td>FeCl3&#8226;6H2O</td>
			<td>Sinopharm Chemical Reagent Co., Ltd</td>
			<td>10011918</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimercaptosuccinic acid</td>
			<td>Aladdin Chemical Reagent Co., Ltd.</td>
			<td>D107254</td>
			<td></td>
		</tr>
		<tr>
			<td>ultrafiltration tube</td>
			<td>Millipore</td>
			<td>UFC910096</td>
			<td></td>
		</tr>
		<tr>
			<td>Tetramethylammonium hydroxide solution</td>
			<td>Aladdin Chemical Reagent Co., Ltd.</td>
			<td>T100882</td>
			<td></td>
		</tr>
		<tr>
			<td>Particle size and zeta potential analyzer</td>
			<td>Malvern, England</td>
			<td>Nano ZS90</td>
			<td></td>
		</tr>
	</tbody>
</table>

polyethyleneimine-coated iron oxide nanoparticles as a vehicle for the delivery of small interfering rna to macrophages in vitro and in vivo

Because of their critical role in regulating immune responses, macrophages have continuously been the subject of intensive research and represent a promising therapeutic target in many disorders, such as autoimmune diseases, atherosclerosis, and cancer. RNAi-mediated gene silencing is a valuable approach of choice to probe and manipulate macrophage function; however, the transfection of macrophages with siRNA is often considered to be technically challenging, and, at present, few methodologies dedicated to the siRNA transfer to macrophages are available. Here, we present a protocol of using polyethyleneimine-coated superparamagnetic iron oxide nanoparticles (PEI-SPIONs) as a vehicle for the targeted delivery of siRNA to macrophages. PEI-SPIONs are capable of binding and completely condensing siRNA when the Fe:siRNA weight ratio reaches 4 and above. In vitro, these nanoparticles can efficiently deliver siRNA into primary macrophages, as well as into the macrophage-like RAW 264.7 cell line, without compromising cell viability at the optimal dose for transfection, and, ultimately, they induce siRNA-mediated target gene silencing. Apart from being used for in vitro siRNA transfection, PEI-SPIONs are also a promising tool for delivering siRNA to macrophages in vivo. In view of its combined features of magnetic property and gene-silencing ability, systemically administered PEI-SPION/siRNA particles are expected not only to modulate macrophage function but also to enable macrophages to be imaged and tracked. In essence, PEI-SPIONs represent a simple, safe, and effective nonviral platform for siRNA delivery to macrophages both in vitro and in vivo.

The size and zeta potential of PEI-SPIONs prepared with this protocol were in the range of 29 - 48 nm (polydispersity index: 0.12 - 0.23) and 30 - 48 mV, respectively. They were stable in water at 4 &#176;C for over 12 months without obvious aggregation. To evaluate their siRNA binding ability, PEI-SPIONs were mixed with siRNA at various Fe:siRNA weight ratios. Figure 1 shows that when the Fe:siRNA weight ratio reaches 4 and above, the band of free siRNA was ...

Watch this Scientific Journal Video about Polyethyleneimine-coated Iron Oxide Nanoparticles as a Vehicle for the Delivery of Small Interfering RNA to Macrophages In Vitro and In Vivo at JoVE.com

Polyethyleneimine-coated Iron Oxide Nanoparticles as a Vehicle for the Delivery of Small Interfering RNA to Macrophages In Vitro and In Vivo

We describe a method of using polyethyleneimine (PEI)-coated superparamagnetic iron oxide nanoparticles for transfecting macrophages with siRNA. These nanoparticles can efficiently deliver siRNA to macrophages in vitro and in vivo and silence target gene expression.

Polyethyleneimine-coated Iron Oxide Nanoparticles as a Vehicle for the Delivery of Small Interfering RNA to Macrophages In Vitro and In Vivo

Because of their critical role in regulating immune responses, macrophages have continuously been the subject of intensive research and represent a ...

This measure can help answer key questions. In the field of humanology. That answer in the function of macrophages under physiological end to pathological conditions.The main advantage of this technique is that polyethyleneimine coated can efficiently en vitro without compromising cell. Under optimal doses. The implications of this technique extend toward therapy and diagnosis of many chronic inflammatory disorders and cancers.Where macrophages play essential role in the pathogenesis. Demonstrating the procedure will be Na Jia. A graduate student from my lab.And Kaixuan Wang a graduate student from Dr.Xiaohua's lab. To prepare allylic acid modified super paramagnetic iron oxide nanoparticles or SPION's first add 28 grams of pharas chloride hexahydrate. And 20 grams pharas selfate heptahydrate to a beaker containing 80 milliliters of deionized water.And use a glass conduit to introduce nitrogen into the solution. Stirring until the solid matter has dissolved. Heat the reaction mixture to 72 degrees Celsius with stirring at 800 rotations per minute.And add 40 milliliters of 28%ammonia water to the beaker. After five minutes add nine milliliters of allylic acid drop wise. And maintain the mixture at 72 degrees Celsius for three hours with continuous stirring.At the end of the incubation cool the resulting solution to room temperature. And precipitate the mixture via magnetic separation according to standard protocols. Then wash the SPION containing precipitate three times with absolute ethyl alcohol.And asperse the precipitate in 100 milliliters of n-hexane. To prepare dimercapto acrylic acid modified SPION's add 800 milligrams of the allylic acid modified SPION's. Dispersed in 200 milliliters of n-hexane and 400 milligrams of dimercapto acrylic acid dispersed in 200 milliliters of acetone into a three neck flask in a water bath at 60 degrees Celsius.Next add 200 microliters of triethylamine drop wise to the flask with stirring at 1000 rotations per minute and refluxing. A black precipitate can be obtained by magnetic separation after five hours. Then use tetramethylammonium hydroxide to adjust the pH of the solution for homogenous dispersal's of the hydrophilic SPION's in deionized water.Degenerate polyethyleneimine coated SPION's add the dimercapto acrylic acid modified SPION's colloidal solution drop wise into a 10 kilodalton polyethyleneimine solution. In a 500 milliliter three neck flask under mechanical stirring at 1000 rotations per minute for two hours. At the end of the incubation add the resulting solution to an ultra filtration tube with a molecular weight cut off of 100 kilodaltons and a content of 15 milliliters.Centrafuse the sample until the remaining solution reaches a one milliliter volume. Add deionized water to the solution to bring the volume back to 15 milliliters. And centrafuse and rehydrate the solution ten more times as just demonstrated.Then filter the solution through a 22 micron filter for storage at four degrees Celsius. To prepare the siRNA nanoparticles first add three microliters of freshly prepared 20 micromolar siRNA solutions to five labeled RNA's free microcentroafused tubes. And add 0, 8, 1.6, 3.2, and 6.4 micrograms of polyethyleneimine SPION's to tubes labeled zero, one, two, four, and eight respectively.After mixing with gentle pipetting, incubate the samples for 30 minutes at room temperature to allow the polyethyleneimine SPION siRNA complexes to form. And prepare a three percent agarose gel with I purity agarose. At the end of the incubation add one microliter of 6X DNA loading buffer per five microliters of sample to each tube and mix carefully.Then load all of the samples onto the gel. And run electrophoresis at five volts per centimeter. Until the bromophenol blue dye migrates two thirds of the length on the gel.One day prior to the transfection wash a mouse microphage like RAW264.7 cell culture with PBS. And treat the cells with one milliliter of 25%trypsin for five to ten minutes at 37 degrees Celsius in a five percent carbon dioxide incubator. When the majority of the cells have detached.Inactivate the trypsin with five milliliters of complete DMEN. Then pippete the solution several times to disperse any cell clusters. Transfer the cell suspension to a sterile 15 milliliter conackel tube for centrifugation.Then re suspend the cells in five milliliters of fresh complete DMEN for counting. Dilute the cells to a 4.5 times ten to the fourth cells per milliliter of complete DMEN concentration. And add two milliliters of medium to each well of a six well plate for a 24 hour incubation in the cell culture incubator.The next day prepare the appropriate ratio of polyethyleneimine SPION siRNA nanoparticles in a 1.5 milliliter RNA stream microcentrifuge tube with gentle mixing as just demonstrated. And add the appropriate volume of polyethyleneimine SPION siRNA nanoparticle complex to each well which has been replaced with one milliliter of fresh medium. Prepare polyethyleneimine SPION si complexes.in this instance many more months of polyethyleneimine SPION can be used Thus minimizing their potential toxicity. Then swirl the plate carefully to achieve an even distribution of the nanoparticles across the well bottoms. Return the plate to the cell culture incubator until subsequent cellular update or gene knockdown deficiency analysis.Polyethyleneimine SPION's with a zeta potential of 30.5 and 37 millivolts do not exhibit an apparent cyto toxicity at concentrations up to 30 micrograms of iron per milliliter. Which is about two fold hire than the concentration normally used for cell transfection. Polyethyleneimine SPION's zeta potential of 48 millivolts however are toxic.Even at the lowest dose examined. As analyzed by flow cytometry, more than 90%of cells can be transfected with fluorescently labeled polyethyleneimine SPION siRNA complexes at 15 micrograms of iron per milliliter. Assessment of the effects of polyethyleneimine SPION siRNA concentrations on cellular internalization by crushing blue staining reveals minimally detectable staining at 7.5 micrograms of iron per milliliter.But clearly visible spots at 15 micrograms of iron per milliliter that do not increase at higher concentrations of iron likely due to polyethyleneimine SPION siRNA uptake saturation. Peritoneal macrophages transfected with polyethyleneimine SPION's harboring specific siRNA exhibit a significant decrease in targe mRNA levels compared to nonspecific siRNA. Suggesting that siRNA can escape from endocytic vesicles into the cytoplasm to reach the RNA interference machinery.Further after intravenous injection of a single dose of polyethyleneimine SPION siRNA nanoparticle complexes flocentimetrical analysis of CD11b positive and CD3 positive cells reveals a more efficient uptake of the nanoparticles by CD11b expressing macrophages than by CD3 positive cells at any time point in all of the organs examined. While attempting this procedure it's important to remember to prepare the polyethyleneimine SPION's with an average data potential not higher than 37 millivolts and to prepare the polyethyleneimine SPION siRNA complexes on the low iron to siRNA ratios. This technique compares the need for researchers to explore therapeutic potential of targeting macrophage in animal motors of human disease such as and cancer.

polyethyleneimine-coated-iron-oxide-nanoparticles-as-vehicle-for

Research

JoVE Journal

Medicine

A Strategy to Identify de Novo Mutations in Common Disorders such as Autism and Schizophrenia

There are several lines of evidence supporting the role of de novo mutations as a mechanism for common disorders, such as autism and schizophrenia. First, the de novo mutation rate in humans is relatively high, so new mutations are generated at a high frequency in the population. However, de novo mutations have not been reported in most common diseases. Mutations in genes leading to severe diseases where there is a strong negative selection against the phenotype, such as lethality in embryonic stages or reduced reproductive fitness, will not be transmitted to multiple family members, and therefore will not be detected by linkage gene mapping or association studies. The observation of very high concordance in monozygotic twins and very low concordance in dizygotic twins also strongly supports the hypothesis that a significant fraction of cases may result from new mutations. Such is the case for diseases such as autism and schizophrenia. Second, despite reduced reproductive fitness1 and extremely variable environmental factors, the incidence of some diseases is maintained worldwide at a relatively high and constant rate. This is the case for autism and schizophrenia, with an incidence of approximately 1% worldwide. Mutational load can be thought of as a balance between selection for or against a deleterious mutation and its production by de novo mutation. Lower rates of reproduction constitute a negative selection factor that should reduce the number of mutant alleles in the population, ultimately leading to decreased disease prevalence. These selective pressures tend to be of different intensity in different environments. Nonetheless, these severe mental disorders have been maintained at a constant relatively high prevalence in the worldwide population across a wide range of cultures and countries despite a strong negative selection against them2. This is not what one would predict in diseases with reduced reproductive fitness, unless there was a high new mutation rate. Finally, the effects of paternal age: there is a significantly increased risk of the disease with increasing paternal age, which could result from the age related increase in paternal de novo mutations. This is the case for autism and schizophrenia3. The male-to-female ratio of mutation rate is estimated at about 4&#x2013;6:1, presumably due to a higher number of germ-cell divisions with age in males. Therefore, one would predict that de novo mutations would more frequently come from males, particularly older males4. A high rate of new mutations may in part explain why genetic studies have so far failed to identify many genes predisposing to complexes diseases genes, such as autism and schizophrenia, and why diseases have been identified for a mere 3% of genes in the human genome. Identification for de novo mutations as a cause of a disease requires a targeted molecular approach, which includes studying parents and affected subjects. The process for determining if the genetic basis of a disease may result in part from de novo mutations and the molecular approach to establish this link will be illustrated, using autism and schizophrenia as examples.

Molecular genetic strategy for finding de novo mutations causing common disorders such as autism and schizophrenia.

There are several lines of evidence supporting the role of de novo mutations as a mechanism for common disorders, such as autism and schizophrenia. First, ...

Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke

Examining molecular mechanisms involved in neuropathological conditions, such as ischemic stroke, can be difficult when using whole animal systems. As such, primary or &#39;neuronal-like&#39; cell culture systems are commonly utilized. While&#160;these systems are relatively easy to work with, and are useful model systems in which various functional outcomes (such as cell death) can be readily quantified, the examined outcomes and pathways in cultured immature neurons (such as excitotoxicity-mediated cell death pathways) are not necessarily the same as those observed in mature brain, or in intact tissue. Therefore, there is the need to develop models in which cellular mechanisms in mature neural tissue can be examined. We have developed an in vitro technique that can be used to investigate a variety of molecular pathways in intact nervous tissue. The technique described herein utilizes rat cortical tissue, but this technique can be adapted to use tissue from a variety of species (such as mouse, rabbit, guinea pig, and chicken) or brain regions (for example, hippocampus, striatum, etc.). Additionally, a variety of stimulations/treatments can be used (for example, excitotoxic, administration of inhibitors, etc.). In conclusion, the brain slice model described herein can be used to examine a variety of molecular mechanisms involved in excitotoxicity-mediated brain injury.

Excitotoxic Stimulation of Brain Microslices as an In vitro Model of Stroke

We have developed a brain slice model which can be used to examine molecular mechanisms involved in excitotoxicity-mediated brain injury.&#160;This technique generates viable mature brain tissue and reduces animal numbers required for experimentation, whilst keeping the neuronal circuitry, cellular interactions, and postsynaptic compartments partly intact.

Examining molecular mechanisms involved in neuropathological conditions, such as ischemic stroke, can be difficult when using whole animal systems. As ...

Slow-release Drug Delivery through Elvax 40W to the Rat Retina: Implications for the Treatment of Chronic Conditions

Diseases of the retina are difficult to treat as the retina lies deep within the eye. Invasive methods of drug delivery are often needed to treat these diseases. Chronic retinal diseases such as retinal oedema or neovascularization usually require multiple intraocular injections to effectively treat the condition. However, the risks associated with these injections increase with repeated delivery of the drug. Therefore, alternative delivery methods need to be established in order to minimize the risks of reinjection. Several other investigations have developed methods to deliver drugs over extended time, through materials capable of releasing chemicals slowly into the eye. In this investigation, we outline the use of Elvax 40W, a copolymer resin, to act as a vehicle for drug delivery to the adult rat retina. The resin is made and loaded with the drug. The drug-resin complex is then implanted into the vitreous cavity, where it will slowly release the drug over time. This method was tested using 2-amino-4-phosphonobutyrate (APB), a glutamate analogue that blocks the light response of the retina. It was demonstrated that the APB was slowly released from the resin, and was able to block the retinal response by 7 days after implantation. This indicates that slow-release drug delivery using this copolymer resin is effective for treating the retina, and could be used therapeutically with further testing.

This paper details how Elvax 40W can be used as a slow-release method for drug delivery to the adult rat retina. The protocol for preparing, loading, and delivering the drug-resin complex to the eye is described.

Diseases of the retina are difficult to treat as the retina lies deep within the eye. Invasive methods of drug delivery are often needed to treat these ...

Isolating and Using Sections of Bovine Mesenteric Artery and Vein as a Bioassay to Test for Vasoactivity in the Small Intestine

Mammalian gastrointestinal systems are constantly exposed to compounds (desirable and undesirable) that can have an effect on blood flow to and from that system. Changes in blood flow to the small intestine can result in effects on the absorptive functions of the organ. Particular interest in toxins liberated from feedstuffs through fermentative and digestive processes has developed in ruminants as an area where productive efficiencies could be improved. The video associated with this article describes an in vitro bioassay developed to screen compounds for vasoactivity in isolated cross-sections of bovine mesenteric artery and vein using a multimyograph. Once the blood vessels are mounted and equilibrated in the myograph, the bioassay itself can be used: as a screening tool to evaluate the contractile response or vasoactivity of compounds of interest; determine the presence of receptor types by pharmacologically targeting receptors with specific agonists; determine the role of a receptor with the presence of one or more antagonists; or determine potential interactions of compounds of interest with antagonists. Through all of this, data are collected real-time, tissue collected from a single animal can be exposed to a large number of different experimental treatments (an in vitro advantage), and represents vasculature on either side of the capillary bed to provide an accurate picture of what could be happening in the afferent and efferent blood supply supporting the small intestine.

The small intestine is frequently exposed to toxins that can influence blood flow and negatively impact nutrient absorption. Using a multimyograph and mesenteric artery and vein isolates, compounds or toxins of interest can be screened for vasoactivity.

Mammalian gastrointestinal systems are constantly exposed to compounds (desirable and undesirable) that can have an effect on blood flow to and from that ...

Intrauterine Telemetry to Measure Mouse Contractile Pressure In Vivo

A complex integration of molecular and electrical signals is needed to transform a quiescent uterus into a contractile organ at the end of pregnancy. Despite the discovery of key regulators of uterine contractility, this process is still not fully understood. Transgenic mice provide an ideal model in which to study parturition. Previously, the only method to study uterine contractility in the mouse was ex vivo isometric tension recordings, which are suboptimal for several reasons. The uterus must be removed from its physiological environment, a limited time course of investigation is possible, and the mice must be sacrificed. The recent development of radiometric telemetry has allowed for longitudinal, real-time measurements of in vivo intrauterine pressure in mice. Here, the implantation of an intrauterine telemeter to measure pressure changes in the mouse uterus from mid-pregnancy until delivery is described. By comparing differences in pressures between wild type and transgenic mice, the physiological impact of a gene of interest can be elucidated. This technique should expedite the development of therapeutics used to treat myometrial disorders during pregnancy, including preterm labor.

Intrauterine Telemetry to Measure Mouse Contractile Pressure In Vivo

This manuscript provides a protocol for implanting telemeters in the mouse for the purpose of measuring intrauterine pressures during pregnancy.

A complex integration of molecular and electrical signals is needed to transform a quiescent uterus into a contractile organ at the end of pregnancy. ...

Depletion of Mouse Cells from Human Tumor Xenografts Significantly Improves Downstream Analysis of Target Cells

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic patient tumors in different assays1. Human tumor xenografts represent the gold standard with respect to tumor biology, drug discovery, and metastasis research 2-4. Tumor xenografts can be derived from different types of material like tumor cell lines, tumor tissue from primary patient tumors4 or serially transplanted tumors. When propagated in vivo, xenografted tissue is infiltrated and vascularized by cells of mouse origin. Multiple factors such as the tumor entity, the origin of xenografted material, growth rate and region of transplantation influence the composition and the amount of mouse cells present in tumor xenografts. However, even when these factors are kept constant, the degree of mouse cell contamination is highly variable.
Contaminating mouse cells significantly impair downstream analyses of human tumor xenografts. As mouse fibroblasts show high plating efficacies and proliferation rates, they tend to overgrow cultures of human tumor cells, especially slowly proliferating subpopulations. Mouse cell derived DNA, mRNA, and protein components can bias downstream gene expression analysis, next-generation sequencing, as well as proteome analysis 5. To overcome these limitations, we have developed a fast and easy method to isolate untouched human tumor cells from xenografted tumor tissue. This procedure is based on the comprehensive depletion of cells of mouse origin by combining automated tissue dissociation with the benchtop tissue dissociator and magnetic cell sorting. Here, we demonstrate that human target cells can be can be obtained with purities higher than 96% within less than 20 min independent of the tumor type.

Human tumor xenografts are vascularized and infiltrated by cells of mouse origin during the growth phase in vivo. To circumvent the bias caused by these contaminating cells during downstream analysis, we developed a method allowing for comprehensive depletion of all mouse cells by magnetic cell sorting.

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic ...

Optimized Analysis of In Vivo and In Vitro Hepatic Steatosis

Establishing a system of procedures to qualitatively and quantitatively characterize in vivo and in vitro hepatic steatosis is important for metabolic study in the liver. Here, numerous assays are described to comprehensively measure the phenotype and parameters of hepatic steatosis in mouse and hepatocyte models. 
Combining the physiological, histological, and biochemical methods, this system can be used to assess the progress of hepatic steatosis. In vivo, the measurements of body weight and nuclear magnetic resonance (NMR) provide a general understanding of mice in a non-invasive manner. Hematoxylin and Eosin (H&amp;E) and Oil Red O staining determine the histological morphology and lipid deposition of liver tissue under nutrient overload conditions, such as high-fat diet feeding. Next, the total lipid contents are isolated by chloroform/methanol extraction, which are followed by a biochemical analysis for triglyceride and cholesterol. Moreover, mouse primary hepatocytes are treated with high glucose plus insulin to stimulate lipid accumulation, an efficient in vitro model to mimic diet-induced hyperglycemia and hyperinsulinemia in vivo. Then, the lipid deposition is measured by Oil Red O staining and chloroform/methanol extraction. Oil Red O staining determines intuitive hepatic steatotic phenotypes, while the lipid extraction analysis determines the parameters that can be analyzed statistically. The present protocols are of interest to scientists in the fields of fatty liver diseases, insulin resistance, and type 2 diabetes.

Optimized Analysis of In Vivo and In Vitro Hepatic Steatosis

Here, optimized methods to generate in vivo and in vitro models of hepatic steatosis and to analyze the steatotic phenotypes and related physiological parameters are described.

Establishing a system of procedures to qualitatively and quantitatively characterize in vivo and in vitro hepatic steatosis is important for metabolic ...

Neonatal Murine Cochlear Explant Technique as an In Vitro Screening Tool in Hearing Research

While there have been remarkable advances in hearing research over the past few decades, there is still no cure for Sensorineural Hearing Loss (SNHL), a condition that typically involves damage to or loss of the delicate mechanosensory structures of the inner ear. Sophisticated in vitro and ex vivo assays have emerged in recent years, enabling the screening of an increasing number of potentially therapeutic compounds while minimizing resources and accelerating efforts to develop cures for SNHL. Though homogenous cultures of certain cell types continue to play an important role in current research, many scientists now rely on more complex organotypic cultures of murine inner ears, also known as cochlear explants. The preservation of organized cellular structures within the inner ear facilitates the in situ evaluation of various components of the cochlear infrastructure, including inner and outer hair cells, spiral ganglion neurons, neurites, and supporting cells. Here we present the preparation, culture, treatment, and immunostaining of neonatal murine cochlear explants. The careful preparation of these explants facilitates the identification of mechanisms that contribute to SNHL and constitutes a valuable tool for the hearing research community.

Neonatal Murine Cochlear Explant Technique as an In Vitro Screening Tool in Hearing Research

The goal of this protocol is to demonstrate the preparation, culture, treatment, and immunostaining of neonatal murine cochlear explants. The technique can be utilized as an in vitro screening tool in hearing research.

While there have been remarkable advances in hearing research over the past few decades, there is still no cure for Sensorineural Hearing Loss (SNHL), a ...

In Vitro and In Vivo Detection of Mitophagy in Human Cells, C. Elegans, and Mice

Mitochondria are the powerhouses of cells and produce cellular energy in the form of ATP. Mitochondrial dysfunction contributes to biological aging and a wide variety of disorders including metabolic diseases, premature aging syndromes, and neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). Maintenance of mitochondrial health depends on mitochondrial biogenesis and the efficient clearance of dysfunctional mitochondria through mitophagy. Experimental methods to accurately detect autophagy/mitophagy, especially in animal models, have been challenging to develop. Recent progress towards the understanding of the molecular mechanisms of mitophagy has enabled the development of novel mitophagy detection techniques. Here, we introduce several versatile techniques to monitor mitophagy in human cells, Caenorhabditis elegans (e.g., Rosella and DCT-1/ LGG-1 strains), and mice (mt-Keima). A combination of these mitophagy detection techniques, including cross-species evaluation, will improve the accuracy of mitophagy measurements and lead to a better understanding of the role of mitophagy in health and disease.

In Vitro and In Vivo Detection of Mitophagy in Human Cells, C. Elegans, and Mice

Mitophagy, the process of clearing damaged mitochondria, is necessary for mitochondrial homeostasis and health maintenance. This article presents some of the latest mitophagy detection methods in human cells, Caenorhabditis elegans, and mice.

Mitochondria are the powerhouses of cells and produce cellular energy in the form of ATP. Mitochondrial dysfunction contributes to biological aging and a ...

In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur

Endochondral fracture healing is a complex process involving the development of fibrous, cartilaginous, and osseous tissue in the fracture callus. The amount of the different tissues in the callus provides important information on the fracture healing progress. Available in vivo techniques to longitudinally monitor the callus tissue development in preclinical fracture-healing studies using small animals include digital radiography and &#181;CT imaging. However, both techniques are only able to distinguish between mineralized and non-mineralized tissue. Consequently, it is impossible to discriminate cartilage from fibrous tissue. In contrast, magnetic resonance imaging (MRI) visualizes anatomical structures based on their water content and might therefore be able to noninvasively identify soft tissue and cartilage in the fracture callus. Here, we report the use of an MRI-compatible external fixator for the mouse femur to allow MRI scans during bone regeneration in mice. The experiments demonstrated that the fixator and a custom-made mounting device allow repetitive MRI scans, thus enabling longitudinal analysis of fracture-callus tissue development.

In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur

The evaluation of tissue development in the fracture callus during endochondral bone healing is essential to monitor the healing process. Here, we report the use of a magnetic resonance imaging (MRI)-compatible external fixator for the mouse femur to allow MRI scans during bone regeneration in mice.

Endochondral fracture healing is a complex process involving the development of fibrous, cartilaginous, and osseous tissue in the fracture callus. The ...