MR was funded by a fellowship from the Danish cancer society (R146-A9394-16-S2). MFB and MKT were funded by AUFF NOVA (AUFF-E-2015-FLS-9-8). MR and MFB were co-funded by Graduate School, HEALTH, AU. The E.F.W. laboratory is supported by grants from the Spanish Ministry of Economy (SAF2015-70857, co-funded by the ERDF-EU) and an ERC advanced grant (741888 - CSI-Fun).
We want to thank Liliana Fajardo Mellor (Genes, Development and Disease; National Cancer Research Center) for critical reading of the manuscript.

This protocol involves a surgical procedure in laboratory mice. All animal experiments must be individually reviewed and approved by an Institutional Animal Care and Use Committee (IACUC). As the approach is based on animal recovery and survival, ensure appropriate anesthesia, pain management, and an aseptic surgical environment at all time. Use a heating pad to prevent hypothermia during surgery and until recovery from anesthesia.
1. Starting Considerations
<ol>
	<li>Depending on the virus used, different titer requirements may apply; dilute the virus accordingly. 
	NOTE: In this example, an Adeno-associated virus diluted in PBS is injected at a titer of 1 x 1012 IU/mL. The virus has serotype 9 and contains guide RNA to Pten and expression of Cre protein under a ubiquitin promotor (Figure 1). Loss of Pten increased pAKT and proliferation of the prostatic epithelium13.</li>
	<li>Use male mice at an age of 8&#160;weeks at the time of surgery to ensure adequate prostate development. 
	NOTE: Mice shown in this experiment are Rosa26-LSL-Cas9-EGFP knockin mice on C57BL/6J background12 (Figure 1).</li>
	<li>Freshly prepare a general anesthesia mix and if possible keep it sterile. 
	NOTE: For better animal recovery after surgery, an anesthesia antidote is highly recommended.
	<ol>
		<li>To prepare a total volume of 5 mL anesthetic, mix 0.15 mL medetomidine hydrochloride (1 mg/mL), 0.4 mL midazolam (5 mg/mL), and 0.25 mL butorphanol (10 mg/mL) with 4.2 mL sterile saline water. 
		NOTE: Alternative anesthesia methods, such as inhalable isoflurane, can be used according to the institutional animal care guidelines.</li>
		<li>To reverse the effect of medetomidine hydrochloride post-surgery, mix 0.1 mL atipamezole (5 mg/mL) with 4.9 mL sterile saline water.</li>
	</ol>
	</li>
	<li>Prepare an aseptic surgical environment by proper disinfection and sterilization. Autoclave surgical instruments before use.</li>
</ol>
2. Virus-delivery to the Murine Prostate
<ol>
	<li>Anesthetize the animal by intraperitoneal injection with a sterile 1 mL syringe and a 27G x &#189;&#34; needle. Use an anesthesia dose of 0.01 mL/g body weight. If the procedure lasts longer than 30 min, maintain anesthesia by injecting 1/3 of the starting dose every 30 min.</li>
	<li>Examine the anesthetic depth by assessing muscle relaxation, pedal withdrawal, and palpebral reflexes. When loss of reflexes is observed, shave the lower abdomen of the animal.</li>
	<li>Carefully cover the animal&#39;s eyes with veterinary ophthalmic ointment using a sterile cotton swab to prevent blindness due to lack of corneal reflex.</li>
	<li>Wipe the shaved abdomen with 70% ethanol and 10% povidone iodine to disinfect the surgical area.&#160;Scrub the surgical area from the center of the surgical area toward the periphery.&#160;</li>
	<li>Perform a vertical skin incision at the low-abdominal midline of approximately 1 cm using a sterile surgical scissor.</li>
	<li>Lift the peritoneum using a fine point forceps to prevent damaging the organs that are laying underneath. Carefully make an &#60; 8 mm incision using surgical scissors through the peritoneum. 
	NOTE: In contrast to human, a rodent&#39;s prostate gland comprises four separate lobes. The anterior lobe is attached to the seminal vesicle.</li>
	<li>Gently move the fat tissue aside to uncover the seminal vesicle. Using a ring forceps, carefully lift up the seminal vesicle until the anterior prostate can be identified (Figure 1).</li>
	<li>Inject a total volume of 30 &#181;L virus (3 x 1010 viral particles) solution in the anterior prostate epithelium using a 0.5 mL insulin syringe with a 30G x 8 mm needle. Minimize leakage and ensure the fluid is absorbed within the tissue, forming a small bubble. Place the seminal vesicle back in the abdominal cavity.</li>
	<li>Suture the peritoneum with 2-3 simple interrupted stitches using 6-0 absorbable sutures with a 13 mm, 3/8 circle, and a taper point needle.</li>
	<li>Staple the skin with 3 sterile 4.8 x 6.5 mm clips lifting the skin with forceps to avoid damaging the peritoneum.</li>
	<li>For better recovery, apply the anesthesia antidote in a dose of 0.01 mL/g body weight by intraperitoneal injection using a sterile 1 mL syringe and a 27G x &#189;&#34; needle. Carefully place the animal back in its cage.</li>
</ol>
3. Post-surgery Procedures
<ol>
	<li>Keep the cage with mice that underwent surgery on a heating pad for 1 h after the procedure, to prevent hypothermia until fully recovered. If the antidote is applied, the animal should be awake a few minutes after the injection.</li>
	<li>Monitor the animals daily for appropriate wound healing and pain indications. If necessary, administer additional pain killers according to institutional animal care guidelines.</li>
	<li>Remove skin clips after 4-5 days, once the wound is closed.</li>
</ol>

<ol>
	<li>Ferlay, 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=Cancer+incidence+and+mortality+worldwide:+sources,+methods+and+major+patterns+in+GLOBOCAN+2012.">Cancer incidence and mortality worldwide: sources, methods and major patterns in GLOBOCAN 2012.</a> Int J Cancer. 136, E359-E386 (2015).</li><li>Gerlinger, 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=Intratumor+heterogeneity+and+branched+evolution+revealed+by+multiregion+sequencing.">Intratumor heterogeneity and branched evolution revealed by multiregion sequencing.</a> N Engl J Med. 366, 883-892 (2012).</li><li>Robinson, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrative+Clinical+Genomics+of+Advanced+Prostate+Cancer.">Integrative Clinical Genomics of Advanced Prostate Cancer.</a> Cell. 162, 454 (2015).</li><li>Gama Sosa, M. A., De Gasperi, R., Elder, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+transgenesis:+an+overview.">Animal transgenesis: an overview.</a> Brain Struct Funct. 214, 91-109 (2010).</li><li>Wu, X., 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=Generation+of+a+prostate+epithelial+cell-specific+Cre+transgenic+mouse+model+for+tissue-specific+gene+ablation.">Generation of a prostate epithelial cell-specific Cre transgenic mouse model for tissue-specific gene ablation.</a> Mech Dev. 101, 61-69 (2001).</li><li>Ma, X., 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=Targeted+biallelic+inactivation+of+Pten+in+the+mouse+prostate+leads+to+prostate+cancer+accompanied+by+increased+epithelial+cell+proliferation+but+not+by+reduced+apoptosis.">Targeted biallelic inactivation of Pten in the mouse prostate leads to prostate cancer accompanied by increased epithelial cell proliferation but not by reduced apoptosis.</a> Cancer Res. 65, 5730-5739 (2005).</li><li>Chen, Z., 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=Crucial+role+of+p53-dependent+cellular+senescence+in+suppression+of+Pten-deficient+tumorigenesis.">Crucial role of p53-dependent cellular senescence in suppression of Pten-deficient tumorigenesis.</a> Nature. 436, 725-730 (2005).</li><li>Leow, C. C., Wang, X. D., Gao, W. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+method+of+generating+prostate-specific+Cre-LoxP+gene+switching+via+intraductal+delivery+of+adenovirus.">Novel method of generating prostate-specific Cre-LoxP gene switching via intraductal delivery of adenovirus.</a> Prostate. 65, 1-9 (2005).</li><li>Thomsen, M. K., 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=Loss+of+JUNB/AP-1+promotes+invasive+prostate+cancer.">Loss of JUNB/AP-1 promotes invasive prostate cancer.</a> Cell Death Differ. 22, 574-582 (2015).</li><li>Cho, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=a+novel+GEM+model+for+metastatic+prostate+cancer+analysis+and+therapy,+reveals+myc+as+a+driver+of+Pten-mutant+metastasis.">a novel GEM model for metastatic prostate cancer analysis and therapy, reveals myc as a driver of Pten-mutant metastasis.</a> Cancer Discov. 4, 318-333 (2014).</li><li>Cho, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+in+vivo+validation+of+candidate+drivers+derived+from+the+PTEN-mutant+prostate+metastasis+genome.">Rapid in vivo validation of candidate drivers derived from the PTEN-mutant prostate metastasis genome.</a> Methods. 77-78, 197-204 (2015).</li><li>Platt, R. 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=CRISPR-Cas9+knockin+mice+for+genome+editing+and+cancer+modeling.">CRISPR-Cas9 knockin mice for genome editing and cancer modeling.</a> Cell. 159, 440-455 (2014).</li><li>Wang, S., 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=Prostate-specific+deletion+of+the+murine+Pten+tumor+suppressor+gene+leads+to+metastatic+prostate+cancer.">Prostate-specific deletion of the murine Pten tumor suppressor gene leads to metastatic prostate cancer.</a> Cancer Cell. 4, 209-221 (2003).</li><li>Liu, W., 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=Copy+number+analysis+indicates+monoclonal+origin+of+lethal+metastatic+prostate+cancer.">Copy number analysis indicates monoclonal origin of lethal metastatic prostate cancer.</a> Nat Med. 15, 559-565 (2009).</li><li>Haffner, M. C., 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=Tracking+the+clonal+origin+of+lethal+prostate+cancer.">Tracking the clonal origin of lethal prostate cancer.</a> J Clin Invest. 123, 4918-4922 (2013).</li><li>Daya, S., Berns, K. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+therapy+using+adeno-associated+virus+vectors.">Gene therapy using adeno-associated virus vectors.</a> Clin Microbiol Rev. 21, 583-593 (2008).</li><li>Price, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+Aspects+of+Development+and+Structure+in+the+Prostate.">Comparative Aspects of Development and Structure in the Prostate.</a> Natl Cancer Inst Monogr. 12, 1-27 (1963).</li><li>McNeal, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomy+of+the+prostate:+an+historical+survey+of+divergent+views.">Anatomy of the prostate: an historical survey of divergent views.</a> Prostate. 1, 3-13 (1980).</li><li>Thomsen, M. K., 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=SOX9+elevation+in+the+prostate+promotes+proliferation+and+cooperates+with+PTEN+loss+to+drive+tumor+formation.">SOX9 elevation in the prostate promotes proliferation and cooperates with PTEN loss to drive tumor formation.</a> Cancer Res. 70, 979-987 (2010).</li></ol>

The authors have nothing to disclose.

In this protocol, we describe a method to alter gene expression in the anterior lobe of the murine prostate by virus injection, creating a powerful new mouse model for prostate cancer (Figure 2). The successful administration of an Adenovirus was first described by Leow et al. in 20058. We have previously shown how an Adenovirus coding for a Cre recombinase protein can replace time-consuming cross-breeding of a Cre allele for tissue-specific deletion <sup cla...

Detection and treatment of prostate cancer have significantly improved over the last decade. Still, the incidence of prostate cancer is increasing, following life expectancy. With an estimated 1.1 million new cases worldwide, it is among the most common causes of cancer-related death in men 1. Prostate cancer is slow in its development, but when the cancer has progressed to an advanced metastatic state, prognosis is poor due to limited treatment options. So far, only a few genes have been identified as common drivers in this cancer, and its heterogeneity and multifocality impedes detection of biomarkers and targetable disease drivers2,3.
Classical techniques of generating GEMMs are often impaired by their complexity, timely expenses, and costs. Conditional knockout models have been widely used to study prostate cancer candidate genes, that result in embryonic lethality when inactivated in the germline4. Most common models involve a prostate-specific Cre recombinase driven by either a modified Probasin5 or a PSA6 promoter integrated in the GEMM by additional cross-breeding. In these models, the gene of interest will be targeted in the majority of prostate epithelial cells, generating hyperplasia in the entire organ, which may impair the animal&#39;s urinary tract function7.
Viral delivery of the Cre protein by injection into the anterior lobe of the murine prostate can resolve this problem by only targeting a few cells8. Taking laboratories technical prerequisites, expertise, and objectives into account, the method benefits from a broad range of possible variations. Successful approaches utilizing Adenovirus targeting JunB and Pten9 or Lentivirus targeting Pten and Trp5310 have been shown amongst others. Adding transgenes, such as luciferase, to the viral construct or to the GEMM will furthermore enable non-invasive monitoring of disease progression via bioluminescence imaging11.
Genome editing based on the CRISPR/Cas9 technology reveals a new and rapid opportunity to study cancer through rapid generation of somatic knockouts12. Viral delivery of single guide RNAs (sgRNAs) directed to the anterior lobe of the murine prostate establishes a physiologically more relevant model of prostate cancer. By this means, single cells carrying chosen mutations can form clones that are capable of expansion and invasion. Furthermore, use of guide RNAs for multiple target genes will generate cell clones with alterations in different genes. This will allow tumor heterogeneity and a natural selection pressure on cancer progression, which can reveal the importance of each gene alteration or epistatic mechanisms.
Here we present a method to deliver viral particles to the murine prostate for alteration of gene expression. By a small abdominal incision, the murine anterior prostate lobe is exposed and viral particles are injected into the lobe. Five days post-surgery, surgical clips can be removed from the skin and the prostatic cancer can be analyzed from 8 weeks after. Overall, this is a rapid and cost-efficient procedure, which has little impact on the mouse and allows larger tumor to develop without compromising the mouse.

<table><tbody><tr><td>&lt;strong&gt;Equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>B6J.129(B6N)-Gt(ROSA)26Sor&lt;sup&gt;tm1(CAG-cas9*,-EGFP)Fezh&lt;/sup&gt;/J mice</td><td>The Jackson Laboratory</td><td>26175</td><td></td></tr><tr><td>0,5 ml U-100 insulin syringe</td><td>BD</td><td>324825</td><td>for virus injection</td></tr><tr><td>1 ml syringe</td><td>BD</td><td>300013</td><td>for anesthesia injection</td></tr><tr><td>30 G 1/2&#039;&#039; needle</td><td>BD</td><td>304000</td><td>for anesthesia injection</td></tr><tr><td>6-0 Polysorb Suture</td><td>Medtronic</td><td>GL889</td><td>to close the peritoneum</td></tr><tr><td>Disposable sterilized surgery drape</td><td>multiple suppliers</td><td></td><td></td></tr><tr><td>Heating pad</td><td>multiple suppliers</td><td></td><td></td></tr><tr><td>Povidone-Iodine Prep Pad</td><td>Fisher Scientific</td><td>06-669-70</td><td></td></tr><tr><td>Trimming machine</td><td>Aesculap</td><td>GT415</td><td>to shave the abdomen</td></tr><tr><td>Dumont Forceps</td><td>F.S.T</td><td>11252-00</td><td></td></tr><tr><td>Halsey Micro Needle Holder</td><td>F.S.T</td><td>12500-12</td><td></td></tr><tr><td>Iris Scissors</td><td>F.S.T</td><td>14094-11</td><td></td></tr><tr><td>Narrow Pattern Forceps</td><td>F.S.T</td><td>11002-12</td><td></td></tr><tr><td>Ring Forceps</td><td>F.S.T</td><td>11106-09</td><td></td></tr><tr><td>Wound Clip System Handle incl. Clips</td><td>F.S.T</td><td>12030-01</td><td>to close the skin</td></tr><tr><td>Wound Clip System Remover</td><td>F.S.T</td><td>12030-04</td><td></td></tr><tr><td>Microscope</td><td>Leica</td><td></td><td>different models have been used</td></tr><tr><td>&lt;strong&gt;Reagents&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>1x PBS</td><td>Gibco</td><td>10010-023</td><td></td></tr><tr><td>Antisedan</td><td></td><td></td><td>obtained from the animal facility</td></tr><tr><td>Butorphanol</td><td></td><td></td><td>obtained from the animal facility</td></tr><tr><td>Medetomidinhydrochlorid</td><td></td><td></td><td>obtained from the animal facility</td></tr><tr><td>Midazolam</td><td></td><td></td><td>obtained from the animal facility</td></tr><tr><td>100% Ethanol</td><td>Fisher Scientific</td><td>22-032-103</td><td></td></tr><tr><td>Eye ointment</td><td>Takeda</td><td>7242</td><td></td></tr><tr><td>Virus (AAV, AV)</td><td>multiple suppliers</td><td></td><td>virus used in this protocol is an in-house production</td></tr><tr><td>pAKT antibody</td><td>CST</td><td>4060</td><td>used 1:200 dillution</td></tr><tr><td>GFP anitbody</td><td>CST</td><td>2956</td><td>used 1:100 dillution</td></tr></tbody></table>

virus delivery of crispr guides to the murine prostate for gene alteration

With an increasing incidence of prostate cancer, identification of new tumor drivers or modulators is crucial. Genetically engineered mouse models (GEMM) for prostate cancer are hampered by tumor heterogeneity and its complex microevolution dynamics. Traditional prostate cancer mouse models include, amongst others, germline and conditional knockouts, transgenic expression of oncogenes, and xenograft models. Generation of de novo mutations in these models is complex, time-consuming, and costly. In addition, most of traditional models target the majority of the prostate epithelium, whereas human prostate cancer is well known to evolve as an isolated event in only a small subset of cells. Valuable models need to simulate not only prostate cancer initiation, but also progression to advanced disease.
Here we describe a method to target a few cells in the prostate epithelium by transducing cells by viral particles. The delivery of an engineered virus to the murine prostate allows alteration of gene expression in the prostate epithelia. Virus type and quantity will hereby define the number of targeted cells for gene alteration by transducing a few cells for cancer initiation and many cells for gene therapy. Through surgery-based injection in the anterior lobe, distal from the urinary track, the tumor in this model can expand without impairing the urinary function of the animal. Furthermore, by targeting only a subset of prostate epithelial cells the technique enables clonal expansion of the tumor, and therefore mimics human tumor initiation, progression, as well as invasion through the basal membrane.
This novel technique provides a powerful prostate cancer model with improved physiological relevance. Animal suffering is limited, and since no additional breeding is required, overall animal count is reduced. At the same time, analysis of new candidate genes and pathways is accelerated, which in turn is more cost efficient.

To assess virus delivery to the murine prostate, samples were analyzed three months after the surgery. The Rosa26-LSL-Cas9-EGFP mice12 express GFP in cells that have been exposed to Cre protein expressed by the virus. The prostate samples were examined with a fluorescence microscopy to identify areas with GFP signal (Figure 2A). The GFP signal indicates Cre activity in the prostate epithelium but not whether gene editing has been induc...

Watch this Scientific Journal Video about Virus Delivery of CRISPR Guides to the Murine Prostate for Gene Alteration at JoVE.com

Virus Delivery of CRISPR Guides to the Murine Prostate for Gene Alteration

This protocol describes a newly established method for virus delivery to the murine prostate. Using either CRISPR/Cas9 technology, gene overexpression, or Cre recombinase delivery, the technique allows orthotopic alteration of gene expression and implements a novel mouse model for prostate cancer.

With an increasing incidence of prostate cancer, identification of new tumor drivers or modulators is crucial. Genetically engineered mouse models (GEMM) ...

virus-delivery-crispr-guides-to-murine-prostate-for-gene

Research

JoVE Journal

Cancer Research

8.6K Views.  Aarhus University. Dit protocol beschrijft een nieuw opgerichte methode voor virus levering aan de lymfkliertest prostaat. Met behulp van technologie van de CRISPR/Cas9, gene overexpressie of Cre recombinase levering, de techniek kunt orthotopic wijziging van genexpressie en implementeert een roman muismodel voor prostaatkanker.

Video: Virus Delivery of CRISPR Guides to the Murine Prostate for Gene Alteration

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. ...

Genetics

Generation of Genetically Modified Mice through the Microinjection of Oocytes

The use of genetically modified mice has significantly contributed to studies on both physiological and pathological in vivo processes. The pronuclear injection of DNA expression constructs into fertilized oocytes remains the most commonly used technique to generate transgenic mice for overexpression. With the introduction of CRISPR technology for gene targeting, pronuclear injection into fertilized oocytes has been extended to the generation of both knockout and knockin mice. This work describes the preparation of DNA for injection and the generation of CRISPR guides for gene targeting, with a particular emphasis on quality control. The genotyping procedures required for the identification of potential founders are critical. Innovative genotyping strategies that take advantage of the "multiplexing" capabilities of CRISPR are presented herein. Surgical procedures are also outlined. Together, the steps of the protocol will allow for the generation of genetically modified mice and for the subsequent establishment of mouse colonies for a plethora of research fields, including immunology, neuroscience, cancer, physiology, development, and others.

The microinjection of mouse oocytes is commonly used for both classic transgenesis (i.e., the random integration of transgenes) and CRISPR-mediated gene targeting. This protocol reviews the latest developments in microinjection, with a particular emphasis on quality control and genotyping strategies.

The use of genetically modified mice has significantly contributed to studies on both physiological and pathological in vivo processes. The pronuclear ...

Developmental Biology

In Vivo CRISPR/Cas9 Screening to Simultaneously Evaluate Gene Function in Mouse Skin and Oral Cavity

Genetically modified mouse models (GEMM) have been instrumental in assessing gene function, modeling human diseases, and serving as preclinical model to assess therapeutic avenues. However, their time-, labor- and cost-intensive nature limits their utility for systematic analysis of gene function. Recent advances in genome-editing technologies overcome those limitations and allow for the rapid generation of specific gene perturbations directly within specific mouse organs in a multiplexed and rapid manner. Here, we describe a CRISPR/Cas9-based method (Clustered Regularly Interspaced Short Palindromic Repeats) to generate thousands of gene knock-out clones within the epithelium of the skin and oral cavity of mice, and provide a protocol detailing the steps necessary to perform a direct&#160;in vivo&#160;CRISPR&#160;screen for tumor suppressor genes. This approach can be applied to other organs or other CRISPR/Cas9 technologies such as CRISPR-activation or CRISPR-inactivation to study the biological function of genes during tissue homeostasis or in various disease settings.

Here we describe a rapid and direct in vivo CRISPR/Cas9 screening methodology using ultrasound-guided in utero embryonic lentiviral injections to simultaneously assess functions of several genes in the skin and oral cavity of immunocompetent mice.

Genetically modified mouse models (GEMM) have been instrumental in assessing gene function, modeling human diseases, and serving as preclinical model to ...

Efficient Genome Editing of Mice by CRISPR Electroporation of Zygotes

With exceptional efficiency, accuracy, and ease, the CRISPR/Cas9 system has significantly improved genome editing in cell culture and lab animal experiments. When generating animal models, the electroporation of zygotes offers higher efficiency, simplicity, cost, and throughput as an alternative to the gold standard method of microinjection. Electroporation is also gentler, with higher viability, and reliably delivers Cas9/single-guide RNA (sgRNA) ribonucleoproteins (RNPs) into the zygotes of common laboratory mouse strains (e.g., C57BL/6J and C57BL/6N) that approaches 100% delivery efficiency. This technique enables insertion/deletion (indels) mutations, point mutations, the deletion of whole genes or exons, and small insertions in the range of 100-200 bp to insert LoxP or short tags like FLAG, HA, or V5. While constantly being improved, here we present the current state of CRISPR-EZ in a protocol that includes sgRNA production through in vitro transcription, embryo processing, RNP assembly, electroporation, and the genotyping of preimplantation embryos. A graduate-level researcher with minimal experience manipulating embryos can obtain genetically edited embryos in less than 1 week using this protocol. Here, we offer a straightforward, low-cost, efficient, high-capacity method that could be used with mouse embryos.

Here, we describe a simple technique intended for the efficient generation of genetically modified mice called CRISPR RNP Electroporation of Zygotes (CRISPR-EZ). This method delivers editing reagents by electroporation into embryos at an efficiency approaching 100%. This protocol is effective for point mutations, small genomic insertions, and deletions in mammalian embryos.

With exceptional efficiency, accuracy, and ease, the CRISPR/Cas9 system has significantly improved genome editing in cell culture and lab animal ...

Designing, Packaging, and Delivery of High Titer CRISPR Retro and Lentiviruses via Stereotaxic Injection

Replication defective lentiviruses or retroviruses are capable of stably integrating transgenes into the genome of an infected host cell. This technique has been widely used to encode fluorescent proteins, opto- or chemo-genetic controllers of cell activity, or heterologous expression of human genes in model organisms. These viruses have also successfully been used to deliver recombinases to relevant target sites in transgenic animals, or even deliver small hairpin or micro RNAs in order to manipulate gene expression. While these techniques have been fruitful, they rely on transgenic animals (recombinases) or frequently lack high efficacy and specificity (shRNA/miRNA). In contrast, the CRISPR/Cas system uses an exogenous Cas nuclease which targets specific sites in an organism's genome via an exogenous guide RNA in order to induce double stranded breaks in DNA. These breaks are then repaired by non-homologous end joining (NHEJ), producing insertion and deletion (indel) mutations that can result in deleterious missense or nonsense mutations. This manuscript provides detailed methods for the design, production, injection, and validation of single lenti/retro virus particles that can stably transduce neurons to express a fluorescent reporter, Cas9, and sgRNAs to knockout genes in a model organism.

The CRISPR/Cas9 system offers the potential to make targeted genome editing accessible and affordable to the scientific community. This protocol is intended to demonstrate how to create viruses that will knockout a gene of interest using the CRISPR/Cas9 system, and then inject them stereotaxically into the adult mouse brain.

Replication defective lentiviruses or retroviruses are capable of stably integrating transgenes into the genome of an infected host cell. This technique ...

Neuroscience

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.

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 ...

Medicine

Retroviral Transduction of Guide RNA for Gene Editing in Th17 Differentiation

Retroviral CRISPR/Cas9-Mediated Gene Targeting for the Study of Th17 Differentiation in Vitro

T helper cells that produce IL-17A, known as Th17 cells, play a critical role in immune defense and are implicated in autoimmune disorders. CD4 T cells can be stimulated with antigens and well-defined cytokine cocktails in vitro to mimic Th17 cell differentiation in vivo. Research has been conducted extensively on the Th17 differentiation regulation mechanisms using the in vitro Th17 polarization assay.
Conventional Th17 polarization methods typically involve obtaining na&#239;ve CD4 T cells from genetically modified mice to study the effects of specific genes on Th17 differentiation and function. These methods can be time-consuming and costly and may be influenced by cell-extrinsic factors from the knockout animals. Thus, a protocol using retroviral transduction of guide RNA to introduce gene knockout in CRISPR/Cas9 knockin primary mouse T cells serves as a very useful alternative approach. This paper presents a protocol to differentiate na&#239;ve primary T cells into Th17 cells following retroviral-mediated gene targeting, as well as the subsequent flow cytometry analysis methods for assaying infection and differentiation efficiency.

We present a protocol for retroviral transduction of guide RNA into primary T cells from Cas9 transgenic mice, providing an efficient alternative for gene editing in studying Th17 differentiation.

T helper cells that produce IL-17A, known as Th17 cells, play a critical role in immune defense and are implicated in autoimmune disorders. CD4 T cells ...

Immunology and Infection

Novel Method of Plasmid DNA Delivery to Mouse Bladder Urothelium by Electroporation

Genetically engineered mouse models (GEMMs) are extremely valuable in revealing novel biological insights into the initiation and progression mechanisms of human diseases such as cancer. Transgenic and conditional knockout mice have been frequently used for gene overexpression or ablation in specific tissues or cell types in vivo. However, generating germline mouse models can be time-consuming and costly. Recent advancements in gene editing technologies and the feasibility of delivering DNA plasmids by viral infection have enabled rapid generation of non-germline autochthonous mouse cancer models for several organs. The bladder is an organ that has been difficult for viral vectors to access, due to the presence of a glycosaminoglycan layer covering the urothelium. Here, we describe a novel method developed in lab for efficient delivery of DNA plasmids into the mouse bladder urothelium in vivo. Through intravesical instillation of pCAG-GFP DNA plasmid and electroporation of surgically exposed bladder, we show that the DNA plasmid can be delivered specifically into the bladder urothelial cells for transient expression. Our method provides a fast and convenient way for overexpression and knockdown of genes in the mouse bladder, and can be applied to building GEMMs of bladder cancer and other urological diseases.

We describe a novel method for the delivery of DNA plasmid into the urothelial cells of mouse bladder in vivo through urethra catheterization and electroporation. It offers a fast and convenient way for generating autochthonous mouse models of bladder diseases.

Genetically engineered mouse models (GEMMs) are extremely valuable in revealing novel biological insights into the initiation and progression mechanisms ...

Biology

Removal of an Internal Translational Start Site from mRNA While Retaining Expression of the Full-Length Protein

The CRISPR-Cas9 gene-editing system, based on genome repair mechanisms, enables the generation of gene-modified mouse models more quickly and easily relative to traditional homologous recombination. The CRISPR-Cas9 system is particularly attractive when a single-point mutation is desired. The gap junction protein, Connexin 43 (Cx43), is encoded by gene Gja1, which has a single coding exon and cannot be spliced. However, Gja1 produces not only full-length Cx43 protein but up to six N-terminus truncated isoforms by a process known as internal translation, the result of ribosomal translation initiation at internal AUG (Methionine) start sites. GJA1-20k is the most commonly generated truncated isoform of Cx43 initiated at the AUG codon at position 213 of Gja1 mRNA. Because residue 213 occurs at the end of the last transmembrane domain of Cx43, GJA1-20k is effectively the 20 kDa C-terminus tail of Cx43 as an independent protein. Previous investigators identified, in cells, that a critical role of GJA1-20k is to facilitate trafficking of full-length Cx43 gap junction hemichannels to the plasma membrane. To examine this phenomenon in vivo, a mutant mouse with a Gja1 point-mutation was generated that replaces the ATG (Methionine) at residue 213 with TTA (Leucine, M213L mutation). The result of M213L is that Gja1 mRNA and full-length Cx43 are still generated, yet the translation of Gja1-20k is significantly reduced. This report focuses on choosing the restriction enzyme site to develop a one amino acid mutated (Gja1M213L/M213L) mouse model. This protocol describes genetically modified mice by the CRISPR-Cas9 system and rapid genotyping by combining PCR and restriction enzyme treatments.

The present protocol describes a single M213L mutation in Gja1 that retains full-length Connexin43 generation but prevents translation of the smaller GJA1-20k internally translated isoform.

The CRISPR-Cas9 gene-editing system, based on genome repair mechanisms, enables the generation of gene-modified mouse models more quickly and easily ...

CRISPR Gene Editing Tool for MicroRNA Cluster Network Analysis

MicroRNAs (miRNAs) have emerged as important cellular regulators (tumor suppressors, pro-oncogenic factors) of cancer and metastasis. Most published studies focus on a single miRNA when characterizing the role of small RNAs in cancer. However, ~30%&#160;of human miRNA genes are organized in clustered units that are often co-expressed, indicating a complex and coordinated system of noncoding RNA regulation. A clearer understating of how clustered miRNA networks function cooperatively to regulate tumor growth, cancer aggressiveness, and drug resistance is required before translating noncoding small RNAs to the clinic.
The use of a high-throughput clustered regularly interspaced short palindromic repeats (CRISPR)-mediated gene editing procedure has been employed to study the oncogenic role of a genomic cluster of seven miRNA genes located within a locus spanning ~35,000 bp in length in the context of prostate cancer. For this approach, human cancer cell lines were infected with a lentivirus vector for doxycycline (DOX)-inducible Cas9 nuclease grown in DOX-containing medium for 48 h. The cells were subsequently co-transfected with synthetic trans-activating CRISPR RNA (tracrRNA) complexed with genomic site-specific CRISPR RNA (crRNA) oligonucleotides to allow the rapid generation of cancer cell lines carrying the entire miRNA cluster deletion and individual or combination miRNA gene cluster deletions within a single experiment.
The advantages of this high-throughput gene editing system are the ability to avoid time-consuming DNA vector subcloning, the flexibility in transfecting cells with unique guide RNA combinations in a 24-well format, and the lower-cost PCR genotyping using crude cell lysates. Studies using this streamlined approach promise to uncover functional redundancies and synergistic/antagonistic interactions between miRNA cluster members, which will aid in characterizing the complex small noncoding RNA networks involved in human disease and better inform future therapeutic design.

This protocol describes a high-throughput clustered regularly interspaced short palindromic repeats (CRISPR) gene editing workflow for microRNA cluster network analysis that allows the rapid generation of a panel of genetically modified cell lines carrying unique miRNA cluster member deletion combinations as large as 35 kb within a single experiment.

MicroRNAs (miRNAs) have emerged as important cellular regulators (tumor suppressors, pro-oncogenic factors) of cancer and metastasis. Most published ...

Virus Delivery of CRISPR Guides to the Murine Prostate for Gene Alteration

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