Name: delivery of modified mrna in a myocardial infarction mouse model
Uploaded: 2020-06-11T12:30:00
Description: Watch this Scientific Journal Video about Delivery of Modified mRNA in a Myocardial Infarction Mouse Model at JoVE.com

The authors acknowledge Ann Anu Kurian&#160;for her help with this manuscript. This work was funded by a cardiology start-up grant awarded to the Zangi laboratory and also by NIH grant R01 HL142768-01

All animal procedures outlined here have been approved by Icahn School of Medicine at Mount Sinai Institutional Care and Use Committee.
1. Synthesis of modRNA
NOTE: The details of modRNA synthesis can be found in Kondrat et al.13.
<ol>
	<li>Order the plasmid templates (Table of Materials) and generate a clean PCR product to use as the mRNA template.</li>
	<li>Prepare the modRNAs by transcription in vitro with a customized r...

<ol>
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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=Synthetic+chemically+modified+mRNA-based+delivery+of+cytoprotective+factor+promotes+early+cardiomyocyte+survival+post-acute+myocardial+infarction.">Synthetic chemically modified mRNA-based delivery of cytoprotective factor promotes early cardiomyocyte survival post-acute myocardial infarction.</a> Molecular Pharmaceutics. 12 (3), 991-996 (2015).</li><li>Magadum, 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=Ablation+of+a+Single+N-Glycosylation+Site+in+Human+FSTL+1+Induces+Cardiomyocyte+Proliferation+and+Cardiac+Regeneration.">Ablation of a Single N-Glycosylation Site in Human FSTL 1 Induces Cardiomyocyte Proliferation and Cardiac Regeneration.</a> Molecular Therapy - Nucleic Acids. 13, 133-143 (2018).</li><li>Kondrat, J., Sultana, N., Zangi, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+Modified+mRNA+for+Myocardial+Delivery.">Synthesis of Modified mRNA for Myocardial Delivery.</a> Methods in Molecular Biology. 1521, 127-138 (2017).</li><li>Gan, L. 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=Intradermal+delivery+of+modified+mRNA+encoding+VEGF-A+in+patients+with+type+2+diabetes.">Intradermal delivery of modified mRNA encoding VEGF-A in patients with type 2 diabetes.</a> Nature Communication. 10 (1), 871 (2019).</li></ol>

Gene therapy has shown tremendous potential to significantly advance the treatment of cardiac disease. However, traditional tools employed in the initial clinical trials for treatment of HF have shown limited success and are associated with severe side effects. Modified RNA presents a nonviral gene delivery that is continuously gaining popularity as a gene transfer tool in the heart. ModRNA requires no nuclear localization of genes for translation, and thus offers an efficient and fast expression of the protein. Further,...

Gene therapy is a powerful tool involving delivery of nucleic acids for the treatment, cure, or prevention of human diseases. Despite the progress in the diagnostic and therapeutic approaches for heart disease, there has been limited success in the delivery of genes in myocardial infarction (MI) and heart failure (HF). As straightforward as the process of gene therapy seems, it is a markedly complex approach considering the many factors that need to be optimized before employing a particular delivery vehicle. The correct delivery vector should be non-immunogenic, efficient, and stable inside the human body. Efforts in this field have generated two types of delivery systems: viral or non-viral. The widely used viral systems, including gene transfer by adenovirus, retrovirus, lentivirus, or adeno-associated virus, have shown exceptional transduction capacity. However, their use in clinics is limited due to the strong immune response induced1, risk of tumorigenesis2, or the presence of neutralizing antibodies3, all of which remain a major obstacle to broad and effective application of viral vectors in human gene therapy. On the other hand, despite their impressive expression pattern, the delivery of naked plasmid DNA displays a low transfection efficiency, while mRNA transfer presents high immunogenicity and susceptibility to degradation by RNase4.
With the extensive research in the field of mRNA, modRNA has become an attractive tool for delivery of genes to the heart and various other organs due to its numerous advantages over traditional vectors5. Complete replacement of uridine with naturally occurring pseudouridine results in more robust and transient protein expression, with minimal induction of innate immune response and risk of genomic integration6. Recently established protocols use an optimized amount of anti-reverse cap analog (ARCA) that further enhances the protein translation by increasing the stability and transability of the synthetic mRNA7.
Previous reports have shown the expression of various reporter or functional genes delivered by modRNA in the rodent myocardium after MI. With modRNA applications, significant areas of the myocardium, including both cardiomyocytes and noncardiomyocytes, have been successfully transfected post-cardiac injury8 to induce angiogenesis9,10, cardiac cell survival11, and cardiomyocyte proliferation12. A single administration of modRNA encoded for mutated human follistatin-like 1 induces the proliferation of mouse adult CMs and significantly increases cardiac function, decreases scar size, and increases capillary density 4 weeks post-MI12. A more recent study reported improved cardiac function after MI with application of VEGFA modRNA in a swine model10.
Thus, with the increased popularity of modRNA in the cardiac field, it is essential to develop and optimize a protocol for the delivery of modRNA to the heart post-MI. Herein is a protocol describing the preparation and delivery of purified and optimized modRNA in a biocompatible citrate-saline formulation that provides robust, stable protein expression without stimulating any immune response. The method shown in this protocol and video demonstrates the standard surgical procedure of a mouse MI by permanent ligation of the left anterior descending artery (LAD), followed by three site intracardiac injections of modRNA. The aim for this paper is to clearly define a highly accurate and reproducible method of modRNA delivery to the murine myocardium to make modRNA application widely accessible for cardiac gene therapy.

<table>
	<tbody>
		<tr>
			<td>Adenosine triphosphate</td>
			<td>Invitrogen</td>
			<td>AMB13345</td>
			<td>Included in Megascript kit</td>
		</tr>
		<tr>
			<td>Antarctic Phosphatase</td>
			<td>New England Biolabs</td>
			<td>M0289L</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-reverse cap analog, 30-O-Mem7G(50) ppp(50)G</td>
			<td>TriLink Biotechnologies</td>
			<td>N-7003</td>
			<td></td>
		</tr>
		<tr>
			<td>Bioluminescense imaging system</td>
			<td>Perkin Elmer</td>
			<td>124262</td>
			<td>IVIS100 charge-coupled device imaging system</td>
		</tr>
		<tr>
			<td>Blunt retractors</td>
			<td>FST</td>
			<td>18200-09</td>
			<td></td>
		</tr>
		<tr>
			<td>Cardiac tropnin I</td>
			<td>Abcam</td>
			<td>47003</td>
			<td></td>
		</tr>
		<tr>
			<td>Cytidine triphosphate</td>
			<td>Invitrogen</td>
			<td>AMB13345</td>
			<td>Included in Megascript kit</td>
		</tr>
		<tr>
			<td>Dual Anesthesia System</td>
			<td>Harvard Apparatus</td>
			<td>75-2001</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps- Adson</td>
			<td>FST</td>
			<td>91106-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps- Dumont #7</td>
			<td>FST</td>
			<td>91197-00</td>
			<td></td>
		</tr>
		<tr>
			<td>Guanosine triphosphate</td>
			<td>Invitrogen</td>
			<td>AMB13345</td>
			<td>Included in Megascript kit</td>
		</tr>
		<tr>
			<td>In vitro transcription kit</td>
			<td>Invitrogen</td>
			<td>AMB13345</td>
			<td>5X MEGAscript T7 Kit</td>
		</tr>
		<tr>
			<td>Intubation cannula</td>
			<td>Harvard Apparatus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Megaclear kit</td>
			<td>Life Technologies</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse ventilator</td>
			<td>Harvard Apparatus</td>
			<td>73-4279</td>
			<td></td>
		</tr>
		<tr>
			<td>N1-methylpseudouridine-5-triphosphate</td>
			<td>TriLink Biotechnologies</td>
			<td>N-1081</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoDrop Spectrometer</td>
			<td>Thermo Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Olsen hegar needle holder with suture scissors</td>
			<td>FST</td>
			<td>12002-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasmid templates</td>
			<td>GeneArt, Thermo Fisher Scientific</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sharp-Pointed Dissecting Scissors</td>
			<td>FST</td>
			<td>14200-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereomicroscope</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sutures</td>
			<td>Ethicon</td>
			<td>Y433H</td>
			<td>5.00</td>
		</tr>
		<tr>
			<td>Sutures</td>
			<td>Ethicon</td>
			<td>Y432H</td>
			<td>6.00</td>
		</tr>
		<tr>
			<td>Sutures</td>
			<td>Ethicon</td>
			<td>7733G</td>
			<td>7.00</td>
		</tr>
		<tr>
			<td>T7 DNase enzyme</td>
			<td>Invitrogen</td>
			<td>AMB13345</td>
			<td>Included in Megascript kit</td>
		</tr>
		<tr>
			<td>Tape station</td>
			<td>Aligent</td>
			<td>4200</td>
			<td></td>
		</tr>
		<tr>
			<td>Transcription clean up kit</td>
			<td>Invitrogen</td>
			<td>AM1908</td>
			<td>Megaclear</td>
		</tr>
		<tr>
			<td>Ultra-4 centrifugal filters 10k</td>
			<td>Amicon</td>
			<td>UFC801096</td>
			<td></td>
		</tr>
	</tbody>
</table>

delivery of modified mrna in a myocardial infarction mouse model

Myocardial infarction (MI) is a leading cause of morbidity and mortality in the Western world. In the past decade, gene therapy has become a promising treatment option for heart disease, owing to its efficiency and exceptional therapeutic effects. In an effort to repair the damaged tissue post-MI, various studies have employed DNA-based or viral gene therapy but have faced considerable hurdles due to the poor and uncontrolled expression of the delivered genes, edema, arrhythmia, and cardiac hypertrophy. Synthetic modified mRNA (modRNA) presents a novel gene therapy approach that offers high, transient, safe, nonimmunogenic, and controlled mRNA delivery to the heart tissue without any risk of genomic integration. Due to these remarkable characteristics combined with its bell-shaped pharmacokinetics in the heart, modRNA has become an attractive approach for the treatment of heart disease. However, to increase its effectiveness in vivo, a consistent and reliable delivery method needs to be followed. Hence, to maximize modRNA delivery efficiency and yield consistency in modRNA use for in vivo applications, an optimized method of preparation and delivery of modRNA intracardiac injection in a mouse MI model is presented. This protocol will make modRNA delivery more accessible for basic and translational research.

Eight to ten-week-old mice were anesthetized with isoflurane and intubated. After the animal was under anesthesia, the left thoracic region was shaved and sterilized with ethanol, and the heart was exposed for LAD ligation. The left coronary artery was occluded by firmly knotting the suture under the artery (diagram representation Figure 1A). After a successful infarction (indicated by the paling of the left ventricular free wall), a direct injection of 100 &#181;g of Luc or Cre modRNA disso...

Watch this Scientific Journal Video about Delivery of Modified mRNA in a Myocardial Infarction Mouse Model at JoVE.com

Delivery of Modified mRNA in a Myocardial Infarction Mouse Model

This protocol presents a simple and coherent way to transiently upregulate a gene of interest using modRNA after myocardial infarction in mice.

Myocardial infarction (MI) is a leading cause of morbidity and mortality in the Western world. In the past decade, gene therapy has become a promising ...

Modified RNA is a novel method for gene transfer to the heart, and other organs. This protocol will provide accurate approach of delivering desired genes transiently to the heart, post myocardial infarction. This method is not limited to myocardial infarction, but can also be applied to ischemia reperfusion, and transverse aortic constriction models.Modified RNA is being used in several human clinical trials. However, there is no standardized protocol for gene transferred into the heart using this method. Visual demonstration will enable researchers to correctly inject modified RNA at appropriate sites in the heart.Demonstrating the procedule will be Ajit Magadum, a postdoctoral fellow, and Elena Chepurko an animal supervisor from our laboratory. Based on the concentration of the previously prepared at modRNA, calculate the volume of modRNA needed for a 100 microgram injection. Makes equal volumes of sucrose and citrate solutions.Then add the calculated volume of modRNA, and enough saline solution to bring the injection volume to 60 microliters. After anesthetizing the animal, place it ventral side up, with its mouth facing toward the experimenter. Then to maintain an open airway by performing intratracheal intubation, gently pull out the tongue.Adjust the angle of the neck to straighten the intubation path, and push in the intubation cannula. Observe the thoracic movement of the mouse to verify that both lungs are receiving oxygen. The respiratory rate should be approximately 120 breaths per minute.To begin the LAD ligation, turn the mouse carefully onto its right side. lift the skin, and perform a left-sided thoracotomy between the third and fourth ribs. Open the thorax carefully, without touching the lungs with any sharp objects.Place retractors into the incision to keep the thoracic cavity open, providing a clear view of the heart. Next, move the lungs to the edge of the incision, and remove the part of the pericardial sac that is covering the heart. Carefully identify the LAD, a deep light red vessel, located between the pulmonary artery and the left auricle.Ligate the proximal LAD with a single silk suture. Using an insulin syringe, deliver a total of 60 microliters of the modRNA solution to the heart. Inject 20 microliters intramuscularly, at three different sites.One site on each side of the ligation and one in the apex of the heart. The best way to inject the modified RNA in the correct sites, is to observe the discoloration of the tissue under microscope, after the occlusion of LAD. Also when injected, do not go too deep into the tissue to reach the heart chambers into the circulation.Close the thoracic incision in layers. First use was 6-0 silk running sutures to adapt the ribs. Then use 5-0 silk running sutures to close the skin.For the recovery phase, remove the cannula, and allow spontaneous breathing. Place the animal on a heating pad until it regains consciousness. Do not leave the animal unattended until it is fully awake.To manage postsurgical pain, inject buprenorphine subcutaneously at 12 hour intervals for three days. At a dose of 0.1 milligrams per kilogram of body weight. 24 hours after LAD ligation and injection of luciferase modRNA in CFW mice, transfection was validated by checking for luciferase protein expression using a bioluminescence imaging system.The luciferase signal can be clearly detected in images comparing control mice, to mice injected with luciferase modRNA. Quantification of the luciferase signal shows significantly higher protein expression in treated mice than in control mice. Cre modRNA expression was validated by checking its translation and bio distribution in transgenic ROSA26 mTmG mice.24 hours after surgery and cre modRNA injection, arts were fixed and processed for immunostaining with cardiomyocyte marker, cardiac troponin I, and nuclei marker DAPI. Successful cre expression was evident due to the appearance of green colored cardiomyocytes. A merged image shows cre activated cells around the two visible injection sites.Blue is the nuclear stain DAPI. Modified RNA platform can deliver a single gene or gene combinations in variety of organs. And thus can be used for therapeutic purposes, such as correcting genetic disorders, or activating beneficial mechanisms in the body.The unique pharmacokinetics of modified RNA enables us to evaluate gene function immediately after its injection. This enables researcher to target signaling pathways, which are altered in the first few hours of infarction.

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