Tang were partially supported by the American Heart Association: GRNT31430008, NIH-AR070029, NIH-HL086555, NIH-HL134354.

Animals were handled according to approved protocols and animal welfare regulations of the Institutional Animal Care and Use Committee of the Medical College of Georgia at Augusta University.
1. Isolation and Purification of MPC-derived Exosomes
<ol>
	<li>Seed 5 x 106 C2C12 cells in a 15 cm cell culture dish with 20 mL complete Dulbecco&#8217;s modified Eagle&#8217;s medium (DMEM) containing 10% fetal bovine serum (FBS), 100 U/mL penicillin G and 100 &#956;g/mL streptomycin. Incubate at 37 &#176;C and 5% CO2.</li>
	<li>Prepare exosome-depleted medium by ultracentrifugation of FBS at 100,000 x g for 18 h at 4 &#176;C using a swinging bucket rotor. Discard the pellet.</li>
	<li>Replace the complete DMEM with exosome-depleted medium when monolayer cells reach 80% confluence in the culture dish.</li>
	<li>Use a transfer pipette to collect the supernatant from the cell culture dish every 48 h for a total of three times. Collect the supernatant in 50 mL centrifuge tubes, and centrifuge at 150 x g for 10 min to remove the remaining cells.</li>
	<li>Filter the supernatant through a 0.22 &#956;m filter to eliminate cell debris. Ultracentrifuge the filtered medium in ultra-clear tubes using the swinging bucket rotor at 100,000 x g for 120 min at 4 &#176;C to precipitate exosomes.</li>
	<li>Resuspend the exosome-containing pellet in phosphate buffered saline (PBS) and fill the entire ultra-clear tube with PBS. Perform ultracentrifugation of this suspension at 100,000 x g for 120 min at 4 &#176;C to eliminate contaminating proteins.</li>
	<li>Discard the supernatant and resuspend the exosome pellet in 100 &#181;L PBS. Store at -80 &#176;C for future use.</li>
	<li>For electron microscopy analysis, place 3 &#181;L of exosomal suspension on a 200 mesh formvar-coated copper electron microscope grid for 5 min at room temperature. Continue with standard uranyl acetate staining23. Examine the semi-dry grid by transmission electron microscopy.</li>
</ol>
2. Intramyocardial Exosome Delivery
NOTE: We used six mice in each group.
<ol>
	<li>Anesthetize DBA/2J-DMDMDX mice (male; age &#62; 10 months; body weight (BW) &#62; 18 g) with intraperitoneal (i.p.) injection of 100 mg/kg BW of ketamine combined with 10 mg/kg BW of xylazine, and confirm the depth of anesthesia by toe pinch.</li>
	<li>Fix each mouse in supine position on a surgical platform by using tape to secure each limb and place a 3-0 suture horizontally below the upper teeth to hold the upper jaw in place.</li>
	<li>Apply the depilatory cream to the left side of the mouse chest to remove the fur from the skin.</li>
	<li>Perform endotracheal intubation via oral cavity using a 24 G catheter, and ventilate the mouse with room air at a rate of 195 breaths/min using a rodent ventilator (see the Table of Materials).</li>
	<li>Disinfect the skin with 75% alcohol and 10% povidone iodine.</li>
	<li>Make a 10&#8210;15 mm oblique incision from the left sternal edge to the left armpit, cut the pectoralis major and pectoralis minor by a scissor, then make a left thoracotomy through the fourth intercostal space. Gently insert the retractor bands to spread the thoracic cavity to a width of 10 mm. Take care to avoid damage to the left lung.</li>
	<li>Use two straight tweezers to remove the pericardium, pull them apart, and place them behind the retractor tips to expose the heart. Inject MPC-Exo (50 &#956;g in 30 &#181;L PBS) or 30 &#956;L PBS (as a control) intramyocardially into the anterior wall of the left ventricle using a 31 G insulin needle at one site.</li>
	<li>Use 6-0 nylon sutures to close the thoracic cavity, pectoralis muscles and skin in sequence.</li>
	<li>Recover mice. Once rhythmic, spontaneous breathing is present, remove the mice from the ventilator, and extubate. Observe and record the mice condition after surgery.</li>
</ol>
3. Echocardiography
NOTE: A single observer blinded to the experimental groups performs echocardiography and data analysis.
<ol>
	<li>Two days after PBS/exosome transplantation, anesthetize the mice with 1&#8210;2% isoflurane.</li>
	<li>Fix a mouse in supine position using tape, and apply the preheated acoustic gel on the left chest area.</li>
	<li>Assess left ventricular function by echocardiography as previously described16,24.
	<ol>
		<li>Obtain the parasternal long axis view of the left ventricle (LV) in two dimensions (B mode), and then rotate the ultrasound probe 90&#176; to obtain a LV short-axis view at papillary muscle level.</li>
		<li>Record M-mode echocardiographic images and measure left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic volume (LVESD), left ventricular end-diastolic volume (LVEDV), and left ventricular end-systolic volume (LVESV). 
		NOTE: Fractional shortening (FS%) = [(LVEDD &#8722; LVESD) / LVEDD] x 100, and left ventricular ejection fraction (LVEF%) = [(LVEDV &#8722; LVESV) / LVEDV] x&#160;100.</li>
	</ol>
	</li>
</ol>
4. Immunohistochemistry
<ol>
	<li>Two days after PBS/exosome transplantation, anesthetize mice (see step 2.1) and cut the sternum open to expose the thoracic cavity. Dissect the inferior vena cava, and perfuse the heart through the left ventricle apex with 3 mL PBS, followed by 3 mL of 4% paraformaldehyde at room temperature, using a butterfly catheter with a 25 G needle attached to a 5 mL syringe.</li>
	<li>Embed fixed hearts into paraffin, and cut into 5 &#956;m thick sections.</li>
	<li>Deparaffinize slides in xylene and rehydrate in ethanol solutions in following order: 100% xylene (3 min), 100% xylene (3 min), 100% ethanol (1 min), 100% ethanol (1 min), 95% ethanol (1 min), 80% ethanol (1 min), H2O (1 min).</li>
	<li>Fix tissue sections with 4% paraformaldehyde for 8 min at room temperature.</li>
	<li>Immerse slides in sodium citrate (0.01 M, pH 6.0) and perform antigen retrieval using an antigen retriever.</li>
	<li>Permeabilize sections for 1 h at room temperature with 1% polyethylene glycol tert-octylphenyl ether in PBS.</li>
	<li>Block sections with 5% goat serum in PBS for 1 h at room temperature.</li>
	<li>Incubate sections with diluted primary antibody (anti-dystrophin antibody) in PBS (1:100) overnight at 4 &#176;C, then wash three times with PBS for 5 min.</li>
	<li>Incubate sections with diluted secondary antibody (Alexa Fluor 488 conjugated goat anti-rabbit IgG) in PBS (1:400) for 45 min at room temperature.</li>
	<li>Control autofluorescence using an autofluorescence quenching kit (see the Table of Materials).</li>
	<li>Use mounting medium containing DAPI (see the Table of Materials) to mount the slides.</li>
	<li>Observe slides under a confocal microscope.</li>
</ol>

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All authors declares that they have no conflicts of interest.

The method of isolating pure exosomes is essential for studying the function of exosomes. One of the common techniques for exosome isolation is polyethylene glycols (PEGs) mediated precipitation17,18,25. Exosomes can be precipitated in PEGs, and pelleted by low-speed centrifugation. PEG-mediated purification is very convenient, low-cost, it does not need any advanced equipment, but there is concern about the purity of exosomes s...

Duchenne muscular dystrophy (DMD) is an X-linked recessive, progressive neuromuscular disease caused by a mutation in DMD gene and the loss of functional dystrophin1. Dystrophin is expressed primarily in skeletal muscle and myocardium, and is less expressed in smooth muscle, endocrine glands and neurons2,3. DMD is the most common type of muscular dystrophy with an incidence of one per 3,500 to 5,000 newborn boys worldwide4,5. Individuals typically develop progressive muscle necrosis, loss of independent walking by early adolescence, and death in the second to third decades of their lives due to heart failure and respiratory failure6.
Dilated cardiomyopathy, arrhythmias and congestive heart failure are common cardiovascular manifestations of DMD7,8. The disease can&#8217;t be cured, supportive treatment may improve symptoms or delay the progression of heart failure, but it is very difficult to improve the heart function9,10.
Similar to DMD patients, X-linked muscular dystrophy (MDX) mice are deficient in dystrophin protein and present symptoms of cardiomyopathy11, and are therefore widely used in DMD associated cardiomyopathy research. In order to restore dystrophin in affected muscles, allogeneic stem cell therapy has proven to be an effective treatment for DMD12,13,14. Exosomes, 30-150 nm membrane vesicles secreted by various cell types, play a key role in cell-to-cell communication through genetic material transport, such as messenger RNA (mRNA) and non-coding RNAs15,16,17,18,19,20,21.
Our previous studies have shown that exosomes derived from myogenic progenitor cells (MPC), such as C2C12 cell line, can transfer dystrophin mRNA to host cardiomyocytes after direct cardiac injection22, indicating that allogeneic delivery of MPC-derived exosomes (MPC-Exo) can transiently restore DMD gene expression in MDX mice. This article focuses on MPC-Exo purification and transplantation techniques.

<table border="0" cellpadding="0" cellspacing="0" style="width:1064px;" width="1064">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:424px;">0.22-&#956;m Filter</td>
			<td style="width:280px;">Fisherbrand</td>
			<td style="width:185px;">09-720-004</td>
			<td style="width:175px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">15-cm Cell Culture Dish</td>
			<td>Thermo Fisher Scientific</td>
			<td>157150</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">24-gauge catheter</td>
			<td style="width:280px;">TERUMO</td>
			<td>SR-OX2419CA</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">31-gauge insulin needle</td>
			<td style="width:280px;">BD</td>
			<td>328291</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">4% paraformaldehyde&#160;</td>
			<td style="width:280px;">Affymetrix</td>
			<td>AAJ19943K2</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">50 mL Centrifuge Tubes</td>
			<td>Thermo Fisher Scientific</td>
			<td>339652</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">6-0 suture</td>
			<td style="width:280px;">Pro Advantage by NDC</td>
			<td>P420697</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Alexa Fluor 488 goat anti-rabbit IgG</td>
			<td style="width:280px;">Thermo Fisher Scientific</td>
			<td>A-11008</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Antibiotic Antimycotic Solution</td>
			<td>Corning&#160;</td>
			<td>30-004-CI</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti-Dystrophin antibody</td>
			<td style="width:280px;">Abcam</td>
			<td>ab15277</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Antigen retriever&#160;</td>
			<td style="width:280px;">Aptum Biologics</td>
			<td>R2100-US</td>
			<td>Antigen recovery</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Autofluorescence Quenching Kit&#160;</td>
			<td style="width:280px;">Vector Laboratories</td>
			<td>SP-8400</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">C2C12 cell line</td>
			<td>ATCC</td>
			<td>CRL-1772</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Centrifuge</td>
			<td>Unico</td>
			<td>C8606</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Change-A-Tip High Temp Cauteries</td>
			<td>Bovie Medical Corporation</td>
			<td>HIT</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Confocal microscopy</td>
			<td style="width:280px;">Zeiss</td>
			<td>Zeiss 780 Upright Confocal</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DBA/2J-mdx mice</td>
			<td>The Jackson Laboratory</td>
			<td>013141</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMEM</td>
			<td>Corning&#160;</td>
			<td>10-013-CM</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fetal Bovine Serum (FBS)</td>
			<td>Corning&#160;</td>
			<td>35-011-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Goat serum&#160;</td>
			<td style="width:280px;">MP Biomedicals, LLC</td>
			<td>191356</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Isoflurane</td>
			<td style="width:280px;">Patterson Veterinary</td>
			<td>07-893-1389</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ketamine</td>
			<td style="width:280px;">Henry Schein</td>
			<td>056344</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mounting Medium with DAPI&#160;</td>
			<td style="width:280px;">Vector Laboratories</td>
			<td>H-1500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse Retractor Set</td>
			<td>Kent Scientific</td>
			<td>SURGI-5001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Polyethylene glycol tert-octylphenyl ether</td>
			<td style="width:280px;">Fisher Scientific</td>
			<td>BP151-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Rodent ventilator</td>
			<td style="width:280px;">Harvard Apparatus</td>
			<td>55-7066</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SW-28 Ti rotor</td>
			<td>Beckman</td>
			<td>342207</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">The Vevo 2100 Imaging Platform</td>
			<td style="width:280px;">FUJIFILM VisualSonics</td>
			<td>Vevo 2100</td>
			<td>Ultrasound System&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ultracentrifuge</td>
			<td>Beckman</td>
			<td>365672</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ultra-Clear Tubes</td>
			<td>Beckman</td>
			<td>344058</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Xylazine (XylaMed)</td>
			<td style="width:280px;">Bimeda-MTC Animal Health Inc.</td>
			<td>1XYL003 8XYL006</td>
			<td></td>
		</tr>
	</tbody>
</table>

purification and transplantation of myogenic progenitor cell derived exosomes to improve cardiac function in duchenne muscular dystrophic mice

Duchene Muscular Dystrophy (DMD) is an X-linked recessive genetic disease caused by a lack of functional dystrophin protein. The disease cannot be cured, and as the disease progresses, the patient develops symptoms of dilated cardiomyopathy, arrhythmia, and congestive heart failure. The DMDMDX mutant mice do not express dystrophin, and are commonly used as a mouse model of DMD. In our recent study, we observed that intramyocardial injection of wide type (WT)-myogenic progenitor cells-derived exosomes (MPC-Exo) transiently restored the expression of dystrophin in the myocardium of DMDMDX mutant mice, which was associated with a transient improvement in cardiac function suggesting that WT-MPC-Exo may provide an option to relieve the cardiac symptoms of DMD. This article describes the technique of MPC-Exo purification and transplantation into hearts of DMDMDX mutant mice.

A flow chart for isolating and purifying exosomes from C2C12 cells is shown in Figure 1A. To confirm the presence of exosomes, we performed transmission electron microscopy analysis. Transmission electron microscopy image (Figure 1B) shows the morphology of the bright and round shape vesicles of C2C12 derived exosomes. Western blot analysis confirmed the presence of exosome markers, including CD63 and TSG101 (<strong class="xfig...

Watch this Scientific Journal Video about Purification and Transplantation of Myogenic Progenitor Cell Derived Exosomes to Improve Cardiac Function in Duchenne Muscular Dystrophic Mice at JoVE.com

Purification and Transplantation of Myogenic Progenitor Cell Derived Exosomes to Improve Cardiac Function in Duchenne Muscular Dystrophic Mice

Here, we present a protocol to transiently improve cardiac function in Duchenne muscular dystrophy mice by transplanting exosomes derived from normal myogenic progenitor cells.

Duchene Muscular Dystrophy (DMD) is an X-linked recessive genetic disease caused by a lack of functional dystrophin protein. The disease cannot be cured, ...

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JoVE Journal

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6.0K Views.  Augusta University. Here, we present a protocol to transiently improve cardiac function in Duchenne muscular dystrophy mice by transplanting exosomes derived from normal myogenic progenitor cells.

Video: Purification and Transplantation of Myogenic Progenitor Cell Derived Exosomes to Improve Cardiac Function in Duchenne Muscular Dystrophic Mice

Rearing and Double-stranded RNA-mediated Gene Knockdown in the Hide Beetle, Dermestes maculatus

Advances in genomics have raised the possibility of probing biodiversity at an unprecedented scale. However, sequence alone will not be informative without tools to study gene function. The development and sharing of detailed protocols for the establishment of new model systems in laboratories, and for tools to carry out functional studies, is thus crucial for leveraging the power of genomics. Coleoptera (beetles) are the largest clade of insects and occupy virtually all types of habitats on the planet. In addition to providing ideal models for fundamental research, studies of beetles can have impacts on pest control as they are often pests of households, agriculture, and food industries. Detailed protocols for rearing and maintenance of D. maculatus laboratory colonies and for carrying out dsRNA-mediated interference in D. maculatus are presented. Both embryonic and parental RNAi procedures-including apparatus set up, preparation, injection, and post-injection recovery-are described. Methods are also presented for analyzing embryonic phenotypes, including viability, patterning defects in hatched larvae, and cuticle preparations for unhatched larvae. These assays, together with in situ hybridization and immunostaining for molecular markers, make D. maculatus an accessible model system for basic and applied research. They further provide useful information for establishing procedures in other emerging insect model systems.

Rearing and Double-stranded RNA-mediated Gene Knockdown in the Hide Beetle, Dermestes maculatus

Here, we present protocols for rearing an intermediate-germ beetle, Dermestes maculatus (D. maculatus) in the lab. We also share protocols for embryonic and parental RNAi and methods for analyzing embryonic phenotypes to study gene function in this species.

Advances in genomics have raised the possibility of probing biodiversity at an unprecedented scale. However, sequence alone will not be informative ...

Single-cell Gene Expression Profiling Using FACS and qPCR with Internal Standards

Gene expression measurements from bulk populations of cells can obscure the considerable transcriptomic variation of individual cells within those populations. Single-cell gene expression measurements can help assess the role of noise in gene expression, identify correlations in the expression of pairs of genes, and reveal subpopulations of cells that respond differently to a stimulus. Here, we describe a procedure to measure the expression of up to 96 genes in single mammalian cells isolated from a population growing in tissue culture. Cells are sorted into lysis buffer by fluorescence-activated cell sorting (FACS), and the mRNA species of interest are reverse-transcribed and amplified. Gene expression is then measured using a microfluidic real-time PCR machine, which performs up to 96 qPCR assays on up to 96 samples at a time. We also describe the generation and use of PCR amplicon standards to enable the estimation of the absolute number of each transcript. Compared with other methods of measuring gene expression in single cells, this approach allows for the quantification of more distinct transcripts than RNA FISH at a lower cost than RNA-Seq.

We describe a method to sort single mammalian cells and to quantify the expression of up to 96 target genes of interest in each cell. This method includes the use of internal qPCR standards to enable the estimation of absolute transcript counts.

Gene expression measurements from bulk populations of cells can obscure the considerable transcriptomic variation of individual cells within those ...

Primordial Germ Cell Transplantation for CRISPR/Cas9-based Leapfrogging in Xenopus

The creation of mutant lines by genome editing is accelerating genetic analysis in many organisms. CRISPR/Cas9 methods have been adapted for use in the African clawed frog, Xenopus, a longstanding model organism for biomedical research. Traditional breeding schemes for creating homozygous mutant lines with CRISPR/Cas9-targeted mutagenesis have several time-consuming and laborious steps. To facilitate the creation of mutant embryos, particularly to overcome the obstacles associated with knocking out genes that are essential for embryogenesis, a new method called leapfrogging was developed. This technique leverages the robustness of Xenopus embryos to &#34;cut and paste&#34; embryological methods. Leapfrogging utilizes the transfer of primordial germ cells (PGCs) from efficiently-mutagenized donor embryos into PGC-ablated wildtype siblings. This method allows for the efficient mutation of essential genes by creating chimeric animals with wildtype somatic cells that carry a mutant germline. When two F0 animals carrying &#34;leapfrog transplants&#34; (i.e., mutant germ cells) are intercrossed, they produce homozygous, or compound heterozygous, null F1 embryos, thus saving a full generation time to obtain phenotypic data. Leapfrogging also provides a new approach for analyzing maternal effect genes, which are refractory to F0 phenotypic analysis following CRISPR/Cas9 mutagenesis. This manuscript details the method of leapfrogging, with special emphasis on how to successfully perform PGC transplantation.

Primordial Germ Cell Transplantation for CRISPR/Cas9-based Leapfrogging in Xenopus

Genes essential for survival pose technical hurdles for creating mutant lines. Leapfrogging circumvents lethality by combining genome editing with primordial germ cell transplantation to create wild-type animals carrying germline mutations. Leapfrogging also permits the efficient generation of homozygous null mutants in the F1 generation. Here, the transplantation step is demonstrated.

The creation of mutant lines by genome editing is accelerating genetic analysis in many organisms. CRISPR/Cas9 methods have been adapted for use in the ...

Embryo Microinjection and Transplantation Technique for Nasonia vitripennis Genome Manipulation

The jewel wasp Nasonia vitripennis has emerged as an effective model system for the study of processes including sex determination, haplo-diploid sex determination, venom synthesis, and host-symbiont interactions, among others. A major limitation of working with this organism is the lack of effective protocols to perform directed genome modifications. An important part of genome modification is delivery of editing reagents, including CRISPR/Cas9 molecules, into embryos through microinjection. While microinjection is well established in many model organisms, this technique is particularly challenging to perform in N. vitripennis primarily due to its small embryo size, and the fact that embryonic development occurs entirely within a parasitized blowfly pupa. The following procedure overcomes these significant challenges while demonstrating a streamlined, visual procedure for effectively removing wasp embryos from parasitized host pupae, microinjecting them, and carefully transplanting them back into the host for continuation and completion of development. This protocol will strongly enhance the capability of research groups to perform advanced genome modifications in this organism.

Embryo Microinjection and Transplantation Technique for Nasonia vitripennis Genome Manipulation

Microinjection of Nasonia vitripennis embryos is an essential method for generating heritable genome modifications. Described here is a detailed procedure for microinjection and transplantation of Nasonia vitripennis embryos, which will greatly facilitate future genome manipulation in this organism.

The jewel wasp Nasonia vitripennis has emerged as an effective model system for the study of processes including sex determination, haplo-diploid sex ...

Highly Efficient Gene Disruption of Murine and Human Hematopoietic Progenitor Cells by CRISPR/Cas9

Advances in the hematopoietic stem cell (HSCs) field have been aided by methods to genetically engineer primary progenitor cells as well as animal models. Complete gene ablation in HSCs required the generation of knockout mice from which HSCs could be isolated, and gene ablation in primary human HSCs was not possible. Viral transduction could be used for knock-down approaches, but these suffered from variable efficacy. In general, genetic manipulation of human and mouse hematopoietic cells was hampered by low efficiencies and extensive time and cost commitments. Recently, CRISPR/Cas9 has dramatically expanded the ability to engineer the DNA of mammalian cells. However, the application of CRISPR/Cas9 to hematopoietic cells has been challenging, mainly due to their low transfection efficiencies, the toxicity of plasmid-based approaches and the slow turnaround time of virus-based protocols.
A rapid method to perform CRISPR/Cas9-mediated gene editing in murine and human hematopoietic stem and progenitor cells with knockout efficiencies of up to 90% is provided in this article. This approach utilizes a ribonucleoprotein (RNP) delivery strategy with a streamlined three-day workflow. The use of Cas9-sgRNA RNP allows for a hit-and-run approach, introducing no exogenous DNA sequences in the genome of edited cells and reducing off-target effects. The RNP-based method is fast and straightforward: it does not require cloning of sgRNAs, virus preparation or specific sgRNA chemical modification. With this protocol, scientists should be able to successfully generate knockouts of a gene of interest in primary hematopoietic cells within a week, including downtimes for oligonucleotide synthesis. This approach will allow a much broader group of users to adapt this protocol for their needs.

A protocol for fast CRISPR/Cas9-mediated gene disruption in mouse and human primary hematopoietic cells is described in this article. Cas9-sgRNA ribonucleoproteins are introduced via electroporation with sgRNAs generated through in vitro transcription and commercial Cas9. High editing efficiencies are achieved with limited time and financial cost.

Advances in the hematopoietic stem cell (HSCs) field have been aided by methods to genetically engineer primary progenitor cells as well as animal models. ...

Bronchoalveolar Lavage Exosomes in Lipopolysaccharide-induced Septic Lung Injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) represent a heterogeneous group of lung diseases which continues to have a high morbidity and mortality. The molecular pathogenesis of ALI is being better defined; however, because of the complex nature of the disease molecular therapies have yet to be developed. Here we use a lipopolysaccharide (LPS) induced mouse model of acute septic lung injury to delineate the role of exosomes in the inflammatory response. Using this model, we were able to show that mice that are exposed to intraperitoneal LPS secrete exosomes in Broncho-alveolar lavage (BAL) fluid from the lungs that are packaged with miRNA and cytokines which regulate inflammatory response. Further using a co-culture model system, we show that exosomes released from macrophages disrupt expression of tight junction proteins in bronchial epithelial cells. These results suggest that 1) cross talk between innate immune and structural cells through the exosomal shuttling contribute to the inflammatory response and disruption of the structural barrier and 2) targeting these miRNAs may provide a novel platform to treat ALI and ARDS.

Mice exposed to intraperitoneal LPS secrete exosomes in Broncho-alveolar lavage (BAL) fluid that are packaged with miRNAs. Using a co-culture system, we show that exosomes released in the BAL fluid disrupt expression of tight junction proteins in bronchial epithelial cells and increase expression of pro-inflammatory cytokines that accentuate lung injury.

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) represent a heterogeneous group of lung diseases which continues to have a high ...

A Combinatorial Single-cell Approach to Characterize the Molecular and Immunophenotypic Heterogeneity of Human Stem and Progenitor Populations

Immunophenotypic characterization and molecular analysis have long been used to delineate heterogeneity and define distinct cell populations. FACS is inherently a single-cell assay, however prior to molecular analysis, the target cells are often prospectively isolated in bulk, thereby losing single-cell resolution. Single-cell gene expression analysis provides a means to understand molecular differences between individual cells in heterogeneous cell populations. In bulk cell analysis an overrepresentation of a distinct cell type results in biases and occlusions of signals from rare cells with biological importance. By utilizing FACS index sorting coupled to single-cell gene expression analysis, populations can be investigated without the loss of single-cell resolution while cells with intermediate cell surface marker expression are also captured, enabling evaluation of the relevance of continuous surface marker expression. Here, we describe an approach that combines single-cell reverse transcription quantitative PCR (RT-qPCR) and FACS index sorting to simultaneously characterize the molecular and immunophenotypic heterogeneity within cell populations.
In contrast to single-cell RNA sequencing methods, the use of qPCR with specific target amplification allows for robust measurements of low-abundance transcripts with fewer dropouts, while it is not confounded by issues related to cell-to-cell variations in read depth. Moreover, by directly index-sorting single-cells into lysis buffer this method, allows for cDNA synthesis and specific target pre-amplification to be performed in one step as well as for correlation of subsequently derived molecular signatures with cell surface marker expression. The described approach has been developed to investigate hematopoietic single-cells, but have also been used successfully on other cell types.
In conclusion, the approach described herein allows for sensitive measurement of mRNA expression for a panel of pre-selected genes with the possibility to develop protocols for subsequent prospective isolation of molecularly distinct subpopulations.

Bulk gene expression measurements cloud individual cell differences in heterogeneous cell populations. Here, we describe a protocol for how single-cell gene expression analysis and index sorting by Florescence Activated Cell Sorting (FACS) can be combined to delineate heterogeneity and immunophenotypically characterize molecularly distinct cell populations.

Immunophenotypic characterization and molecular analysis have long been used to delineate heterogeneity and define distinct cell populations. FACS is ...

Dissection of Enhancer Function Using Multiplex CRISPR-based Enhancer Interference in Cell Lines

Multiple enhancers often regulate a given gene, yet for most genes, it remains unclear which enhancers are necessary for gene expression, and how these enhancers combine to produce a transcriptional response. As millions of enhancers have been identified, high-throughput tools are needed to determine enhancer function on a genome-wide scale. Current methods for studying enhancer function include making genetic deletions using nuclease-proficient Cas9, but it is difficult to study the combinatorial effects of multiple enhancers using this technique, as multiple successive clonal cell lines must be generated. Here, we present Enhancer-i, a CRISPR interference-based method that allows for functional interrogation of multiple enhancers simultaneously at their endogenous loci. Enhancer-i makes use of two repressive domains fused to nuclease-deficient Cas9, SID and KRAB, to achieve enhancer deactivation via histone deacetylation at targeted loci. This protocol utilizes transient transfection of guide RNAs to enable transient inactivation of targeted regions and is particularly effective at blocking inducible transcriptional responses to stimuli in tissue culture settings. Enhancer-i is highly specific both in its genomic targeting and its effects on global gene expression. Results obtained from this protocol help to understand whether an enhancer is contributing to gene expression, the magnitude of the contribution, and how the contribution is affected by other nearby enhancers.

This protocol describes the steps needed to design and perform multiplexed targeting of enhancers with the deactivating fusion protein SID4X-dCas9-KRAB, also known as enhancer interference (Enhancer-i). This protocol enables the identification of enhancers that regulate gene expression and facilitates the dissection of relationships between enhancers regulating a common target gene.

Multiple enhancers often regulate a given gene, yet for most genes, it remains unclear which enhancers are necessary for gene expression, and how these ...

Isolation, Characterization and MicroRNA-based Genetic Modification of Human Dental Follicle Stem Cells

To date, several stem cell types at different developmental stages are in the focus for the treatment of degenerative diseases. Yet, certain aspects, such as initial massive cell death and low therapeutic effects, impaired their broad clinical translation. Genetic engineering of stem cells prior to transplantation emerged as a promising method to optimize therapeutic stem cell effects. However, safe and efficient gene delivery systems are still lacking. Therefore, the development of suitable methods may provide an approach to resolve current challenges in stem cell-based therapies.
The present protocol describes the extraction and characterization of human dental follicle stem cells (hDFSCs) as well as their non-viral genetic modification. The postnatal dental follicle unveiled as a promising and easily accessible source for harvesting adult multipotent stem cells possessing high proliferation potential. The described isolation procedure presents a simple and reliable method to harvest hDFSCs from impacted wisdom teeth. Also this protocol comprises methods to define stem cell characteristics of isolated cells. For genetic engineering of hDFSCs, an optimized cationic lipid-based transfection strategy is presented enabling highly efficient microRNA introduction without causing cytotoxic effects. MicroRNAs are suitable candidates for transient cell manipulation, as these small translational regulators control the fate and behavior of stem cells without the hazard of stable genome integration. Thus, this protocol represents a safe and efficient procedure for engineering of hDFSCs that may become important for optimizing their therapeutic efficacy.

This protocol describes the transient genetic engineering of dental stem cells extracted from the human dental follicle. The applied non-viral modification strategy may become a basis for the improvement of therapeutic stem cell products.

To date, several stem cell types at different developmental stages are in the focus for the treatment of degenerative diseases. Yet, certain aspects, such ...

Preparation and Gene Modification of Nonhuman Primate Hematopoietic Stem and Progenitor Cells

Hematopoietic stem and progenitor cell (HSPC) transplantation has been a cornerstone therapy for leukemia and other cancers for nearly half a century, underlies the only known cure of human immunodeficiency virus (HIV-1) infection, and shows immense promise in the treatment of genetic diseases such as beta thalassemia. Our group has developed a protocol to model HSPC gene therapy in nonhuman primates (NHPs), allowing scientists to optimize many of the same reagents and techniques that are applied in the clinic. Here, we describe methods for purifying CD34+ HSPCs and long-term persisting hematopoietic stem cell (HSC) subsets from primed bone marrow (BM). Identical techniques can be employed for the purification of other HSPC sources (e.g., mobilized peripheral blood stem cells [PBSCs]). Outlined is a 2 day protocol in which cells are purified, cultured, modified with lentivirus (LV), and prepared for infusion back into the autologous host. Key readouts of success include the purity of the CD34+ HSPC population, the ability of purified HSPCs to form morphologically distinct colonies in semisolid media, and, most importantly, gene modification efficiency. The key advantage to HSPC gene therapy is the ability to provide a source of long-lived cells that give rise to all hematopoietic cell types. As such, these methods have been used to model therapies for cancer, genetic diseases, and infectious diseases. In each case, therapeutic efficacy is established by enhancing the function of distinct HSPC progeny, including red blood cells, T cells, B cells, and/or myeloid subsets. The methods to isolate, modify, and prepare HSPC products are directly applicable and translatable to multiple diseases in human patients.

The goal of this protocol is to isolate nonhuman primate CD34+ cells from primed bone marrow, to gene-modify these cells with lentiviral vectors, and to prepare a product for infusion into the autologous host. The total protocol length is approximately 48 h.

Hematopoietic stem and progenitor cell (HSPC) transplantation has been a cornerstone therapy for leukemia and other cancers for nearly half a century, ...