R.H. is supported by US National Institutes of Health grants (R01HL116546 and R01 AR064241).

The animals used in this protocol were maintained at The Ohio State University Laboratory Animal Resources in accordance with animal use guidelines. All animal studies were authorized by the Institutional Animal Care, Use, and Review Committee of the Ohio State University.
1. Design and Cloning of gRNAs into the CRISPR Vector
<ol>
	<li>Select 2 gRNAs targeting dystrophin intron 20 and intron 23 (i20 and i23) for SaCas9: i20: 5&#39;-GGGCGTTGAAATTCTCATTAC CAGAGT and i23: 5&#39;-CACCGA...

<ol>
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A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome+engineering+using+the+CRISPR-Cas9+system.">Genome engineering using the CRISPR-Cas9 system.</a> Nature protocols. 8, 2281-2308 (2013).</li><li>Zhang, X., Wang, J., Cheng, Q., Zheng, X., Zhao, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiplex+gene+regulation+by+CRISPR-ddCpf1.">Multiplex gene regulation by CRISPR-ddCpf1.</a> Cell discovery. 3, 17018 (2017).</li><li>Zhang, X. H., Tee, L. Y., Wang, X. G., Huang, Q. S., Yang, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Off-target+Effects+in+CRISPR/Cas9-mediated+Genome+Engineering.">Off-target Effects in CRISPR/Cas9-mediated Genome Engineering.</a> Molecular therapy. 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E., 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=Muscle-specific+CRISPR/Cas9+dystrophin+gene+editing+ameliorates+pathophysiology+in+a+mouse+model+for+Duchenne+muscular+dystrophy.">Muscle-specific CRISPR/Cas9 dystrophin gene editing ameliorates pathophysiology in a mouse model for Duchenne muscular dystrophy.</a> Nat Commun. 8, 14454 (2017).</li><li>Hoffman, E. P., Brown, R. H., Kunkel, L. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dystrophin:+the+protein+product+of+the+Duchenne+muscular+dystrophy+locus.">Dystrophin: the protein product of the Duchenne muscular dystrophy locus.</a> Cell. 51, 919-928 (1987).</li><li>Nowak, K. J., Davies, K. 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E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Eteplirsen.">Eteplirsen.</a> Hosp Pharm. 52, 302-305 (2017).</li><li>Sicinski, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+molecular+basis+of+muscular+dystrophy+in+the+mdx+mouse:+a+point+mutation.">The molecular basis of muscular dystrophy in the mdx mouse: a point mutation.</a> Science. 244, 1578-1580 (1989).</li><li>Xu, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CRISPR-mediated+Genome+Editing+Restores+Dystrophin+Expression+and+Function+in+mdx+Mice.">CRISPR-mediated Genome Editing Restores Dystrophin Expression and Function in mdx Mice.</a> Molecular therapy : the journal of the American Society of Gene Therapy. 24, 564-569 (2016).</li><li>El Refaey, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+Vivo+Genome+Editing+Restores+Dystrophin+Expression+and+Cardiac+Function+in+Dystrophic+Mice.">In Vivo Genome Editing Restores Dystrophin Expression and Cardiac Function in Dystrophic Mice.</a> Circ Res. 121, 923-929 (2017).</li><li>Tabebordbar, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+gene+editing+in+dystrophic+mouse+muscle+and+muscle+stem+cells.">In vivo gene editing in dystrophic mouse muscle and muscle stem cells.</a> Science. 351, 407-411 (2016).</li><li>Pozsgai, E. R., Griffin, D. A., Heller, K. N., Mendell, J. R., Rodino-Klapac, L. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=beta-Sarcoglycan+gene+transfer+decreases+fibrosis+and+restores+force+in+LGMD2E+mice.">beta-Sarcoglycan gene transfer decreases fibrosis and restores force in LGMD2E mice.</a> Gene therapy. 23, 57-66 (2016).</li><li>Chicoine, L. 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=Plasmapheresis+eliminates+the+negative+impact+of+AAV+antibodies+on+microdystrophin+gene+expression+following+vascular+delivery.">Plasmapheresis eliminates the negative impact of AAV antibodies on microdystrophin gene expression following vascular delivery.</a> Mol Ther. 22, 338-347 (2014).</li><li>Chicoine, L. 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=Vascular+delivery+of+rAAVrh74.MCK.GALGT2+to+the+gastrocnemius+muscle+of+the+rhesus+macaque+stimulates+the+expression+of+dystrophin+and+laminin+alpha2+surrogates.">Vascular delivery of rAAVrh74.MCK.GALGT2 to the gastrocnemius muscle of the rhesus macaque stimulates the expression of dystrophin and laminin alpha2 surrogates.</a> Mol Ther. 22, 713-724 (2014).</li><li>Vouillot, L., Thelie, A., Pollet, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+T7E1+and+surveyor+mismatch+cleavage+assays+to+detect+mutations+triggered+by+engineered+nucleases.">Comparison of T7E1 and surveyor mismatch cleavage assays to detect mutations triggered by engineered nucleases.</a> G3. 5, 407-415 (2015).</li><li>Tsai, S. 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In this protocol, we detail all the steps necessary to achieve in vivo cardiac gene editing in postnatal mice using rAAVrh.74-mediated delivery of SaCas9 and two gRNAs. As previously noted, this approach can be used to restore dystrophin expression in dystrophic mice as described in our work27, but it could also enable rapid reverse genetics studies of cardiac-related genes in mice without the lengthy process of the traditional knockout approach to generate and breed knockout mouse models...

The clustered, regularly interspaced, short palindromic repeat (CRISPR) technology represents the most recent advancement in genome engineering and has revolutionized the current practice of genetics in cells and organisms. CRISPR-based genome editing utilizes a single guide RNA (gRNA) to direct a CRISPR-associated endonuclease such as CRISPR-associated protein 9 (Cas9) and Cpf1 to a genomic DNA target that is complementary in sequence to the protospacer encoded by the gRNA with a specific protospacer adjacent motif (PAM)1,2. The PAM varies depending on the bacterial species of the Cas9 or Cpf1 gene. The most commonly used Cas9 nuclease derived from Streptococcus pyogenes (SpCas9) recognizes a PAM sequence of NGG that is found directly downstream of the target sequence in the genomic DNA, on the non-target strand. At the target site, the Cas9 and Cpf1 proteins generate a double-strand break (DSB), which is then repaired via intrinsic cellular DNA repair mechanisms including non-homologous end joining (NHEJ) and homology-directed repair (HDR) pathways3,4. In the absence of a DNA template for homologous recombination, the DSB is primarily repaired by the error-prone NHEJ pathway, which can result in insertions or deletions (indels) of nucleotides causing frameshift mutations if the DSB were created in the coding region of a gene5,6. Thus, the CRISPR system has been widely used to engineer loss-of-function mutations in various cellular models and whole organisms, in order to investigate the function of a gene. Moreover, the catalytically inactive Cas9 and Cpf1 have been developed to transcriptionally and epigenetically modulate the expression of target genes7,8.
More recently, both SpCas9 and SaCas9 (derived from Staphylococcus aureus) have been packaged into recombinant adeno-associated virus (rAAV) vectors for postnatal gene correction in the animal model of human diseases, particularly, Duchenne muscular dystrophy (DMD)9,10,11,12,13,14,15. DMD is a fatal X-linked recessive disease caused by mutations in the DMD gene, which encodes dystrophin protein16,17, affecting approximately one in 3500 male births according to newborn screening18,19. It is characterized by progressive muscle weakness and wasting. The DMD patients usually lose the ability to walk between 10 and 12 years of age and die of respiratory and/or cardiac failure by the age of 20-30 years20. Notably, cardiomyopathy develops in &#62;90% of DMD patients and represents the leading cause of death in DMD patients21,22. Although Deflazacort (an anti-inflammation drug) and Eteplirsen (an exon skipping medicine for skipping exon 51) have recently been approved for DMD by Food and Drug Administration (FDA)23,24, none of these treatments correct the genetic defect at the genomic DNA level. The mdx mouse, which carries a point mutation at exon 23 of the dystrophin gene, has been widely used as a DMD model25. Furthermore, we previously demonstrated that the functional dystrophin expression was restored by in-frame deletion of the genomic DNA covering exons 21, 22 and 23 in skeletal muscles of mdx mice using intramuscular Ad-SpCas9/gRNA delivery9, and in the heart muscles of mdx/utrophin+/- mice using intravenous and intraperitoneal rAAVrh.74-SaCas9/gRNA delivery26.
In this protocol, we describe in detail every step in postnatal cardiac gene editing to restore dystrophin in mdx/utrophin+/- mice using rAAVrh.74-SaCas9/gRNA vectors, from gRNA design to dystrophin analysis in the heart muscle sections.

<table>
	<tbody>
		<tr>
			<td>Alexa Fluor 555 goat anti-rabbit IgG</td>
			<td>Thermo Fisher Scientific</td>
			<td>A-21428</td>
			<td></td>
		</tr>
		<tr>
			<td>Benzonase Nuclease</td>
			<td>Sigma-Aldrich</td>
			<td>E1014</td>
			<td></td>
		</tr>
		<tr>
			<td>Bio Safety Cabinets</td>
			<td>Thermo Fisher Scientific</td>
			<td>1347</td>
			<td>1300 Series A2 Class II, Type A2</td>
		</tr>
		<tr>
			<td>BsaI</td>
			<td>New England BioLabs Inc</td>
			<td>RO535S</td>
			<td></td>
		</tr>
		<tr>
			<td>Competent cells</td>
			<td>Agilent Technologies</td>
			<td>200314</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell culture dishes, 150mm</td>
			<td>Nest Scientific USA</td>
			<td>715001</td>
			<td></td>
		</tr>
		<tr>
			<td>Cryostat</td>
			<td>Leica Biosystems</td>
			<td></td>
			<td>Leica CM3050S</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Thermo Fisher Scientific</td>
			<td>MT10017CV</td>
			<td>Corning cellgro</td>
		</tr>
		<tr>
			<td>Dystrophin antibody</td>
			<td>Spring Bioscience</td>
			<td>E2660</td>
			<td></td>
		</tr>
		<tr>
			<td>Fast-Ion Midi Plasmdi Kits</td>
			<td>IBI Scientific</td>
			<td>IB47111</td>
			<td></td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>Thermo Fisher Scientific</td>
			<td>26-140-079</td>
			<td></td>
		</tr>
		<tr>
			<td>Filter Unit, 0.45&#956;m</td>
			<td>Thermo Fisher Scientific</td>
			<td>166-0045</td>
			<td></td>
		</tr>
		<tr>
			<td>GoTaq Master Mixes</td>
			<td>Promega</td>
			<td>M7122</td>
			<td></td>
		</tr>
		<tr>
			<td>High-speed plasmid mini kit</td>
			<td>IBI Scientific</td>
			<td>IB47102</td>
			<td></td>
		</tr>
		<tr>
			<td>Horse serum</td>
			<td>Abcam</td>
			<td>ab139501</td>
			<td></td>
		</tr>
		<tr>
			<td>Isotemp 2239 Water Bath</td>
			<td>Thermo Fisher Scientific</td>
			<td>15-460-11Q</td>
			<td></td>
		</tr>
		<tr>
			<td>Isotemp Heat Block</td>
			<td>Thermo Fisher Scientific</td>
			<td>11-718</td>
			<td></td>
		</tr>
		<tr>
			<td>Inverted confocal microscope</td>
			<td>Carl Zeiss Microscopy, LLC</td>
			<td></td>
			<td>LSM 780</td>
		</tr>
		<tr>
			<td>LightCycler 480 instrument</td>
			<td>Roche</td>
			<td>5015243001</td>
			<td>LightCycler 480 Instrument II</td>
		</tr>
		<tr>
			<td>Large Capacity Centrifuge</td>
			<td>Thermo Fisher Scientific</td>
			<td>46-910</td>
			<td>Thermo Scientific Sorvall RC 6 Plus</td>
		</tr>
		<tr>
			<td>Microcentrifuge</td>
			<td>Thermo Fisher Scientific</td>
			<td>75002445</td>
			<td>Sorvall Legend Micro 21R</td>
		</tr>
		<tr>
			<td>Nanodrop spectrophotometers</td>
			<td>Thermo Scientific</td>
			<td>ND2000CLAPTOP</td>
			<td>NanoDrop&#8482; 2000/2000c</td>
		</tr>
		<tr>
			<td>Oligos for i20-F</td>
			<td>Integrated DNA Technologies</td>
			<td></td>
			<td>CACCgGGCGTTGAAATTCTCATTAC</td>
		</tr>
		<tr>
			<td>Oligos for i20-R</td>
			<td>Integrated DNA Technologies</td>
			<td></td>
			<td>AAAC GTAATGAGAATTTCAACGCCc;</td>
		</tr>
		<tr>
			<td>Oligos for i23-F</td>
			<td>Integrated DNA Technologies</td>
			<td></td>
			<td>CACCgCACCGATGAGAGGGAAAGGTC</td>
		</tr>
		<tr>
			<td>Oligos for i23-R</td>
			<td>Integrated DNA Technologies</td>
			<td></td>
			<td>GACCTTTCCCTCTCATCGGTGc</td>
		</tr>
		<tr>
			<td>Oligos</td>
			<td>Integrated DNA Technologies</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>OptiPrep Density Gradient Medium</td>
			<td>Sigma-Aldrich</td>
			<td>D1556-250ML</td>
			<td></td>
		</tr>
		<tr>
			<td>OptiMEM</td>
			<td>Thermo Fisher Scientific</td>
			<td>31985070</td>
			<td></td>
		</tr>
		<tr>
			<td>PEG8000</td>
			<td>Sigma-Aldrich</td>
			<td>89510-1kg-F</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyethylenimine</td>
			<td>Polysciences</td>
			<td>23966</td>
			<td></td>
		</tr>
		<tr>
			<td>Proteinase K</td>
			<td>Sigma-Aldrich</td>
			<td>P2308</td>
			<td></td>
		</tr>
		<tr>
			<td>Quick-Seal centrifuge tube</td>
			<td>Beckman Coulter Inc</td>
			<td>342414</td>
			<td></td>
		</tr>
		<tr>
			<td>QIAquick Gel Extraction kit</td>
			<td>Qiagen</td>
			<td>28704</td>
			<td></td>
		</tr>
		<tr>
			<td>Radiant SYBR Green Hi-ROX qPCR Kits</td>
			<td>Alkali Scientific</td>
			<td>QS2005</td>
			<td></td>
		</tr>
		<tr>
			<td>RevertAid RT Reverse Transcription Kit</td>
			<td>Thermo Fisher Scientific</td>
			<td>K1691</td>
			<td></td>
		</tr>
		<tr>
			<td>Rotor</td>
			<td>Beckman Coulter Inc</td>
			<td>337922</td>
			<td>Type 70Ti</td>
		</tr>
		<tr>
			<td>T4 DNA ligase</td>
			<td>New England BioLabs Inc</td>
			<td>M0202S</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermal Cycler</td>
			<td>Bio-rad</td>
			<td>1861096</td>
			<td></td>
		</tr>
		<tr>
			<td>TRIzol Reagent</td>
			<td>Thermo Fisher Scientific</td>
			<td>15596026</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultracentrifuge</td>
			<td>Beckman Coulter Inc</td>
			<td>8043-30-1192</td>
			<td>Optima le-80k</td>
		</tr>
		<tr>
			<td>Ultra centrifugal filter unit</td>
			<td>MilliporeSigma</td>
			<td>UFC510096</td>
			<td></td>
		</tr>
		<tr>
			<td>VECTASHIELD Mounting Medium with DAPI</td>
			<td>Vector Laboratories, Inc</td>
			<td>H-1200</td>
			<td></td>
		</tr>
	</tbody>
</table>

adeno-associated virus-mediated delivery of crispr for cardiac gene editing in mice

The clustered, regularly interspaced, short, palindromic repeat (CRISPR) system has greatly facilitated genome engineering in both cultured cells and living organisms from a wide variety of species. The CRISPR technology has also been explored as novel therapeutics for a number of human diseases. Proof-of-concept data are highly encouraging as exemplified by recent studies that demonstrate the feasibility and efficacy of gene editing-based therapeutic approach for Duchenne muscular dystrophy (DMD) using a murine model. In particular, intravenous and intraperitoneal injection of the recombinant adeno-associated virus (rAAV) serotype rh.74 (rAAVrh.74) has enabled efficient cardiac delivery of the Staphylococcus aureus CRISPR-associated protein 9 (SaCas9) and two guide RNAs (gRNA) to delete a genomic region with a mutant codon in exon 23 of mouse Dmd gene. This same approach can also be used to knock out the gene-of-interest and study their cardiac function in postnatal mice when the gRNA is designed to target the coding region of the gene. In this protocol, we show in detail how to engineer rAAVrh.74-CRISPR vector and how to achieve highly efficient cardiac delivery in neonatal mice.

The efficacy of the gRNAs to induce the deletion of the target genomic DNA region should be evaluated in cell cultures before packaging into rAAV for in vivo studies. To this end, the gRNAs and SaCas9-expressing constructs were electroporated into C2C12 cells and the genomic DNA was analyzed by PCR with the primers flanking the target sites (Figure 1). A PCR product of ~500 bp indicates successful deletion of the target genomic DNA resulting from gene editing...

Watch this Scientific Journal Video about Adeno-Associated Virus-Mediated Delivery of CRISPR for Cardiac Gene Editing in Mice at JoVE.com

Adeno-Associated Virus-Mediated Delivery of CRISPR for Cardiac Gene Editing in Mice

Here we provide a detailed protocol to carry out in vivo cardiac gene editing in mice using recombinant Adeno-Associated Virus(rAAV)-mediated delivery of CRISPR. This protocol offers a promising therapeutic strategy to treat dystrophic cardiomyopathy in Duchenne muscular dystrophy and can be used to generate cardiac-specific knockout in postnatal mice.

The clustered, regularly interspaced, short, palindromic repeat (CRISPR) system has greatly facilitated genome engineering in both cultured cells and ...

The overall goal of this in vivo cardiac gene editing protocol is to restore dystrophin expression in the heart of dystrophic mice using recombinant adeno-associated virus rh. 74 with CRISPR SaCas9 and guide RNA vectors. This method can help answer key questions in the muscular dystrophy field, such as whether gene editing is a reliable therapeutic strategy to treat the root cause of the cardiomyopathy associated with Duchenne's muscular dystrophy.The main advantage of these techniques are the expression of the corrected dystrophin gene is under its endogenous regulatory control, and this rescue effect is permanent. The implication of this technique extends toward treatment of other genetic disease where correction of mutant gene can be achieved by CRISPR Cas9 gene editing technology. This method not only provides insight into dystrophin restoration in the dystrophic heart, but it can also be used to knock out the gene of interest for reverse genetic studies.Demonstrating the procedure will be Yandi Gao, a technician from our laboratory. The proper design of the guide RNAs, or gRNAs, is critical to the success of this protocol. Select two gRNAs targeting dystrophin intron 20 and intron 23 for the Staphylococcus aureus CRISPR-associated protein nine.The protospacer adjacent motif sequence for each gRNA is underlined and italicized. To anneal the gRNA oligonucleotides, set up a reaction containing 100 micromoles per liter of the gRNA oligonucleotides in 1x annealing buffer. Use the following PCR parameters:95 degrees Celsius for 10 minutes, 90 cycles of 95 to 59 degrees Celsius with a 0.4 degree Celsius decrease per cycle for 20 seconds, 90 cycles of 59 to 32 degrees Celsius with a 0.3 degree Celsius decrease per cycle for 20 seconds, and 20 cycles of 32 to 26 degrees Celsius with a 0.3 degree Celsius decrease per cycle for 20 seconds.Next, prepare to ligate the annealed gRNA oligonucleotides into the CRISP vector in one reaction. Add the following to a tube:one microliter of 50 nanograms per microliter CRISPR vector, one microliter of annealed oligonucleotides, 1.5 microliters of 10x T4 DNA ligase buffer, 0.5 microliters of T4 DNA ligase, one microliter of Bsal, and 10 microliters of double-distilled water. Run the following reaction in a thermocycler:five cycles of 37 degrees Celsius for five minutes and 16 degrees Celsius for 10 minutes, 37 degrees Celsius for 20 minutes, and 80 degrees Celsius for five minutes.Transform the 15-microliter ligation product into 30 microliters of competent cells, and plate the cells on a agar plate containing 100 microgram per milliliter of ampicillin. Culture at 37 degrees Celsius for 24 hours. On the following day, pick five to 10 colonies from the agar plate and culture in LB medium containing 100 microgram per milliliter of ampicillin at 37 degrees Celsius and 250 rpm for three to four hours.To screen the colonies by PCR, prepare reactions that each contain 10 microliters of PCR master mix, eight microliters of double-distilled water, one microliter of E.coli culture, one microliter of U6-forward primer, and one microliter of i20 or i23 gRNA reverse primer. Use the following PCR cycling parameters:95 degrees Celsius for five minutes, followed by 35 cycles of 95 degrees Celsius for 30 seconds, 61 degrees Celsius for 30 seconds, and 72 degrees Celsius for 30 seconds. Once the positive clones have been identified, prepare a five-milliliter culture of each positive clone by adding four milliliters of fresh LB medium containing 100 microgram per milliliter ampicillin and culturing at 37 degrees Celsius and 250 rpm overnight.On the following day, purify the plasmid DNA using the appropriate plasmid extraction kit. The plasmid is subsequently verified by Sanger sequencing with the U6-forward primer. To test the gene editing efficacy of the plasmids, culture C2C12 cells in DMEM supplemented with 10%FBS and 1%Pen-Strep until the cells reach approximately 70%confluency.Electroporate a total of five micrograms of SaCas9/gRNA plasmid mixture in one-to-one molar ratio into C2C12 cells according to the manufacturer's protocol. 48 hours post-transfection, harvest the C2C12 cells, and extract genomic DNA as described in the text protocol. Use the genomic DNA as template to perform PCR for the mouse dystrophin locus.Set up reactions containing the forward primer, the reverse primer, the green PCR master mix, double-distilled water, and 100 nanograms of genomic DNA. Use the same PCR conditions as for screening positive clones. Prior to starting this procedure, prepare the recombinant adeno-associated virus, or rAAV, as described in the text protocol.Administer day three mdx mouse pups with viral particles systemically via an intraperitoneal injection. Allow the mice to recover, and place them back into their home cages. At 10 weeks after rAAV administration, collect tissues from the mice.Snap-freeze the tissues for genomic DNA and RNA extraction, and use cooled isopentane in liquid nitrogen to freeze tissues with optimal cutting temperature compound for cryosectioning. Begin the immunofluorescence staining protocol by fixing the frozen tissue sections with 4%paraformaldehyde at room temperature for five minutes. After 15 minutes, wash the tissue sections two times with PBS.Incubate with blocking solution at room temperature for one hour. Next, incubate with the anti-dystrophin primary antibody at four degrees Celsius overnight. On the following morning, wash the slides with PBS, and then incubate with fluorescent secondary antibodies at room temperature for one hour.Mount the slides using mounting medium with DAPI, and image with an inverted confocal microscope. The efficacy of the gRNAs to induce the deletion of the target genomic DNA region in cell cultures was evaluated by PCR. A PCR product of approximately 500 base pairs indicates successful deletion of the target genomic DNA resulting from gene editing, while the control cells should not yield a band.Once the efficacy of the gRNAs has been confirmed in cell cultures, the gRNAs are packaged into rAAV. The rAAV viral particles are purified and the purity analyzed by SDS-PAGE. The presence of only three bands corresponding to the three capsid proteins indicates high purity.These representative immunofluorescence images of heart sections of wild type, mdx, and mdx mice treated with AAV SaCas9 gRNA systemically show that AAV SaCas9 gRNA restores dystrophin expression in dystrophic mice. After watching this video, you should have a good understanding of how to achieve in vivo cardiac gene editings in postnatal mice using rAAV rh. 74-mediated delivery of SaCas9 and gRNAs.

adeno-associated-virus-mediated-delivery-crispr-for-cardiac-gene

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8.0K visualizações.  Ohio State University Wexner Medical Center. The overall goal of this in vivo cardiac gene editing protocol is to restore dystrophin expression in the heart of dystrophic mice using recombinant adeno-associated virus rh. 74 with CRISPR SaCas9 and guide RNA vectors. This method can help answer key questions in the muscular dystrophy field, such as whether gene editing is a reliable therapeutic strategy to treat the root cause of the cardiomyopathy associated with Duchenne's muscular dystrophy.The main advantage of these techniques...