The authors wish to acknowledge the NINDS, FightSMA, and Families of SMA for financial support. SEGL is supported by NINDS training grant #5T32NS077984-02.

All procedures listed in the protocol have been approved Institute for Animal Use and Care committee (IACUC) of the Ohio State University.
1. Preparation of Workspace
<ol>
	<li>Gather wet ice to anesthetize the mouse pups, an empty cage to segregate the dam from the litter, a dissecting microscope, a light source that can be positioned at an angle to the injection (use of a light source at a 90&#176;&#160;angle to the injection site obscures the vein), a clean surface to place the animal for the injection, cotton swabs, 3/10 cc insulin syringe with 3/8&#8221; 30 G&#160;needle (one per animal) and 1% Evans Blue Dye (made with phosphate buffered saline (PBS)) solution for training.</li>
	<li>Remove the dam to a separate cage while manipulating the pups.</li>
</ol>
2. Injection Procedure
<ol>
	<li>Place a single pup directly on the wet ice for 30-60 sec&#160;to anesthetize the animal. Do not leave the animal on ice too long due to a risk of hypothermia related complications including ventricular fibrillation, tissue hypoxia and metabolic acidosis. 
	NOTE: Our experience is that 30-60 sec&#160;is sufficient to slow the pup movements to allow for injection. If deeper anesthesia is required, inhalants such as 1-2% isoflurane may be appropriate.</li>
	<li>While the animal is on ice, load the syringe with 30 &#956;l of Evans blue dye.</li>
	<li>When the animal is fully anesthetized, confirmed by lack of movement on the ice while still breathing, move it under the microscope. For a right-handed injection, face the animal&#8217;s muzzle to the right. Place the left index finger on the muzzle and the left middle finger caudal to the ear bud so that the ear bud is between the index and middle fingers (Figure 1).</li>
	<li>Examine just anterior to the ear bud for a superficial capillary that moves when the skin is manipulated. This capillary is NOT the target, however identification is important for temporal vein identification. Next, locate a dark, shadowy vein inferior to the capillary that remains fixed regardless of skin position. The temporal vein appears shadowy, runs dorsal to ventral, and feeds into the jugular vein (Figure 1).</li>
	<li>Enter the temporal vein with the needle bevel up. If correctly inserted, it is possible to view the needle bevel fill with blood through the skin. Then depress the plunger slowly and note blanching of the vein down the side of the face.</li>
	<li>Allow the needle to remain within the vein for an added 10-15 sec&#160;to prevent backflow of the injectant.</li>
</ol>
3. Post-injection
<ol>
	<li>After a proper injection, the pup should turn blue almost immediately. Remove the needle and use gentle force to apply a cotton swab to the injection site until the blood clots.</li>
	<li>Monitor the pup for signs of distress. Allow the pup 2-3 min&#160;to recover and rewarm, recognize when the pup is conscious, upright and moving, before returning to the cage. Cup the pups in the investigator&#8217;s gloved hands to provide appropriate warmth to aid in recovery if necessary. Alternatively, place a heating pad under the home cage to facilitate warming the injected pup. Generally after an Evans blue dye injection, euthanize pups. Do not include dye when injecting test material.</li>
	<li>Place the pup back into the home cage and ensure the pup is coated with bedding and/or nestlet to ensure reacceptance by the dam.</li>
	<li>Use a new syringe and cotton swab for each pup to maintain sterility.</li>
</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=Intravenous+administration+of+AAV2/9+to+the+fetal+and+neonatal+mouse+leads+to+differential+targeting+of+CNS+cell+types+and+extensive+transduction+of+the+nervous+system.">Intravenous administration of AAV2/9 to the fetal and neonatal mouse leads to differential targeting of CNS cell types and extensive transduction of the nervous system.</a> FASEB journal : official publication of the Federation of American Societies for Experimental Biology. 25, 3505-3518 (2011).</li><li>Foust, K. 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=Rescue+of+the+spinal+muscular+atrophy+phenotype+in+a+mouse+model+by+early+postnatal+delivery+of+SMN.">Rescue of the spinal muscular atrophy phenotype in a mouse model by early postnatal delivery of SMN.</a> Nat Biotechnol. 28, 271-274 (2010).</li><li>Duque, 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=Intravenous+administration+of+self-complementary+AAV9+enables+transgene+delivery+to+adult+motor+neurons.">Intravenous administration of self-complementary AAV9 enables transgene delivery to adult motor neurons.</a> Mol Ther. 17, 1187-1196 (2009).</li><li>Bostick, B., Ghosh, A., Yue, Y., Long, C., Duan, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systemic+AAV-9+transduction+in+mice+is+influenced+by+animal+age+but+not+by+the+route+of+administration.">Systemic AAV-9 transduction in mice is influenced by animal age but not by the route of administration.</a> Gene Ther. 14, 1605-1609 (2007).</li><li>Miyake, N., Miyake, K., Yamamoto, M., Hirai, Y., Shimada, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+gene+transfer+into+the+CNS+across+the+BBB+after+neonatal+systemic+delivery+of+single-stranded+AAV+vectors.">Global gene transfer into the CNS across the BBB after neonatal systemic delivery of single-stranded AAV vectors.</a> Brain research. 1389, 19-26 (2011).</li><li>Porensky, P. 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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=Percutaneous+intravenous+injection+in+neonatal+mice.">Percutaneous intravenous injection in neonatal mice.</a> Laboratory animal science. 49, 328-330 (1999).</li><li>Bevan, A. 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=Early+heart+failure+in+the+SMNDelta7+model+of+spinal+muscular+atrophy+and+correction+by+postnatal+scAAV9-SMN+delivery.">Early heart failure in the SMNDelta7 model of spinal muscular atrophy and correction by postnatal scAAV9-SMN delivery.</a> Human molecular genetics. 19, 3895-3905 (2010).</li><li>Valori, C. F., 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=Systemic+delivery+of+scAAV9+expressing+SMN+prolongs+survival+in+a+model+of+spinal+muscular+atrophy.">Systemic delivery of scAAV9 expressing SMN prolongs survival in a model of spinal muscular atrophy.</a> Science translational medicine. 2, (2010).</li><li>Foust, K. D., Poirier, A., Pacak, C. A., Mandel, R. J., Flotte, T. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neonatal+intraperitoneal+or+intravenous+injections+of+recombinant+adeno-associated+virus+type+8+transduce+dorsal+root+ganglia+and+lower+motor+neurons.">Neonatal intraperitoneal or intravenous injections of recombinant adeno-associated virus type 8 transduce dorsal root ganglia and lower motor neurons.</a> Hum Gene Ther. 19, 61-70 (2008).</li><li>Guggenbuhl, P., Grosbois, B., Chales, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gaucher+disease.">Gaucher disease.</a> Joint, bone, spine : revue du rhumatisme. 75, 116-124 (2008).</li><li>Daly, T. M., Vogler, C., Levy, B., Haskins, M. E., Sands, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neonatal+gene+transfer+leads+to+widespread+correction+of+pathology+in+a+murine+model+of+lysosomal+storage+disease.">Neonatal gene transfer leads to widespread correction of pathology in a murine model of lysosomal storage disease.</a> Proc Natl Acad Sci U S A. 96, 2296-2300 (1999).</li><li>Daly, T. M., Ohlemiller, K. K., Roberts, M. S., Vogler, C. A., Sands, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevention+of+systemic+clinical+disease+in+MPS+VII+mice+following+AAV-mediated+neonatal+gene+transfer.">Prevention of systemic clinical disease in MPS VII mice following AAV-mediated neonatal gene transfer.</a> Gene Ther. 8, 1291-1298 (2001).</li><li>Wang, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Juvenile+neuronal+ceroid+lipofuscinoses.">Juvenile neuronal ceroid lipofuscinoses.</a> Advances in experimental medicine and biology. 724, 138-142 (2012).</li><li>Forsythe, E., Beales, P. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bardet-Biedl+syndrome.">Bardet-Biedl syndrome.</a> European journal of human genetics. 21, 8-13 (2013).</li><li>Bevan, A. 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=Systemic+gene+delivery+in+large+species+for+targeting+spinal+cord,+brain,+and+peripheral+tissues+for+pediatric+disorders.">Systemic gene delivery in large species for targeting spinal cord, brain, and peripheral tissues for pediatric disorders.</a> Mol Ther. 19, 1971-1980 (2011).</li><li>Yardeni, T., Eckhaus, M., Morris, H. D., Huizing, M., Hoogstraten-Miller, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retro-orbital+injections+in+mice.">Retro-orbital injections in mice.</a> Lab animal. 40, 155-160 (2011).</li><li>Saunders, N. R., Joakim Ek, C., Dziegielewska, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+neonatal+blood-brain+barrier+is+functionally+effective,+and+immaturity+does+not+explain+differential+targeting+of+AAV9.">The neonatal blood-brain barrier is functionally effective, and immaturity does not explain differential targeting of AAV9.</a> Nature biotechnology. 27, 804-805 (2009).</li><li>Foust, K. 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=Therapeutic+AAV9-mediated+suppression+of+mutant+SOD1+slows+disease+progression+and+extends+survival+in+models+of+inherited+ALS.">Therapeutic AAV9-mediated suppression of mutant SOD1 slows disease progression and extends survival in models of inherited ALS.</a> Mol Ther. 21, 2148-2159 (2013).</li></ol>

The authors have nothing to disclose.

Intravascular delivery of agents to the CNS or throughout the body is difficult in neonatal murine models of disease. The described protocol is a quick, relatively non-invasive way to intravenously administer solutions into neonatal mice with minimal equipment requirements. Though the temporal face vein can be viewed by the naked eye, injections may have greater accuracy with the use of the microscope and fiber-optic light source, especially for an unpracticed injector. Intravascular injections in neonatal mice have a high success rate12, and AAV transduction has been observed in early pups even if part of the injectant is administered subcutaneously. The injection is well tolerated by the mouse pups, and dams on FVB/N or C57BL/6 backgrounds tolerate manipulation of the pups very well. However, in rare instances dams can destroy entire litters. These injections can be successfully performed in mice as small as 0.8 g through 1.6 g. Alternative injection routes for neonate mice have been published by us and others including retro-orbital, intrajugular and intraperitoneal10,15,22. We prefer the injection route described here because it is clinically relevant, able to be performed by a single experimenter with no special equipment requirements and allows for a wide range of volumes to be administered.
A common problem experienced when performing injections is difficulty viewing the temporal vein and therefore misplacement of the needle. The fiber-optic light source should be positioned at &#60;90&#176;&#160;and shining downward on the head when being held for best viewing of the vein. Injectors should take time to adjust the light source to suit their needs. Temporal vein observation is significantly decreased if pups are too large, characterized as older then P2 or greater than 2.0 g. A second problem may be determining if the needle bevel has entered the vein. The temporal facial vein is superficial, so care must be taken to avoid entering beneath the vein. Ensuring that the needle bevel is entering parallel to the vein will prevent puncturing through the vein. Needle placement is best verified by slow injection and subsequent blanching of the vein.
The superficial temporal vein is visible on either side of the head. Left-handed individuals may find that facing the animal to the investigator&#8217;s left may be ergonomically better and should be determined for each individual investigator. Should the vein not be visible or is mistargeted on initial attempts, targeting the vein on the opposite side of the head is appropriate. If the vein is punctured on both sides of the head, some leakage may occur through the first site during injection into the second site. Depending on the working distance of the microscope, it may be appropriate to build a small platform on which to inject the animal; for example, an empty Styrofoam container from 50 ml conical tube packaging (Figure 1). This allows the investigator to position the animal near the edge of the platform so that the investigator&#8217;s injecting hand can rest directly on the table. This can improve the angle of entry into the vein and minimize light obstruction.
There are a few limitations to the utility of the protocol including the injection volume, the age window for injections and the unpredictability of the dam response. Injection volumes for pups are limited to 50 &#181;l. We have previously dosed animals with 100 &#181;l, but have observed increased injection related mortality compared to lower volume injections, but others report successfully delivering 100 &#181;l10,12. Further, it has been suggested that increased injection volumes can damage the blood brain barrier23. Often the experimental reagent is mixed with PBS to maintain a constant 50 &#181;l injection volume. We are unaware of studies examining the effect of injection volume on spread throughout the neonate mice, and empirical studies should be performed to identify effects on injection volume for new reagents at a given dose. A second limitation is that the superficial temporal vein is easily visible on the first and second postnatal days. Changes to the animal size, skin pigmentation and thickness combine to obscure the vein at later ages though others report accessing the vein through postnatal day 610,12. Alternatively, we used ultrasound guided cardiac injections to deliver viral vector to the circulation in P5 and P10 animals4. Finally, the acceptance of the mouse dams of the procedure is unpredictable. We have treated FVB/N, C57BL/6 and B6SJL mice across mouse models of neuromuscular disease and autism spectrum disorders. FVB/N mice are the most tolerant while strains on the C57BL/6 background can occasionally destroy individual pups or entire litters, but this a rare occurrence. However, this should be a consideration when planning for sufficient n for an experiment. Dam acceptance can be further influenced by what disease the mouse strain is modeling. For example, a model of an autism spectrum disorder had a much higher rate of pup rejection than expected based on the background strain. Fostering pups may be a consideration if dam acceptance is a concern. Other approaches to limit rejection include performing injections in a separate room from the dam to limit access to pup ultrasonic vocalizations, and to rub the dam&#8217;s nose and/or the pups with a cloth dampened with 70% ethanol to mask any investigator scent. Pups should also be rubbed with dirty bedding to aid in acceptance.
This protocol has been successfully used to treat a mouse model of SMA. SMA is a pediatric neurodegenerative disease that primarily affects lower motor neurons of the spinal cord. Without treatment, this mouse model dies by 15 days after birth on average. After intravenous injections of AAV gene therapy in 1 day-old mice, survival was extended to one year, demonstrating the safety and tolerability of the described injection protocol2,4,14. Similar results were also obtained in the same SMA mouse model following IV injection of antisense oligonucleotides8,9. Future applications include the delivery of other cell and gene therapies, as well as the creation of neonatal models for developmental disorders of the CNS and the periphery to exogenously express a cDNA or an RNAi cassette24. Intravenous injection is an approved clinical method of delivery; therefore, utilization of this technique may be advantageous in preclinical studies for a variety of agents.

Delivery of therapeutics to the central nervous system (CNS) in murine models of pediatric disease remains a challenge. Mice that model newborn disease states are undersized and developmentally immature, and therefore can be difficult to directly inject in appropriate structures within the CNS. Intravascular injection of therapeutic agents is a non-invasive, well tolerated method to deliver cells, drugs, or viral vectors to the entire body including the CNS1-5 and retina3,5-9. Previous publications describe temporal face vein injection using a transilluminator10,11, without a dissection microscope11,12, or requiring two individuals to inject10. The injection technique described in this protocol is advantageous because a single individual can inject pups, and the light source to view the temporal vein is not touching the pup, eliminating the need for surgical tape or the attachment of a pup to a fixed surface such as a transilluminator11. Delivery of adeno-associated viral vector serotype 9 (AAV9) in mice produces robust expression in neurons and astrocytes throughout the brain and spinal cord (Figure 1). Intravascular delivery of viral vectors into the superficial temporal facial vein has been reliably used in various studies in neonatal mice to treat the pediatric neuromuscular disorder Spinal Muscular Atrophy (SMA)2,4,13,14 and ultimately increased the lifespan of treated mice.
Intravascular injection of neonatal mice also effectively targets the peripheral nervous system and peripheral organs (Figure 2). Following injection of AAV, transduction of dorsal root ganglia, liver, heart, skeletal muscle, lung, and myenteric plexus of the gut has been observed1,3,6,7,15. Widespread transduction of the CNS and periphery makes this method of injection ideal for diseases requiring global expression of a transgene, such as Gaucher&#8217;s disease16 and other lysosomal storage diseases17,18, Batten&#8217;s disease and related neuronal ceroid lipofuscinoses,19 and Bardet-Biedl syndrome, a genetic multisystem disorder with onset of symptoms occurring in early childhood20. Intravascular injection into neonatal mice should also be considered as a novel method of modeling system-wide pediatric diseases. This technique has been translated to larger animal models5,21 and intravascular injection already exists as a clinically acceptable method of delivering therapeutics.
The current protocol describes a simple, efficient method of delivering agents to neonatal mice through the superficial temporal face vein no later than postnatal day 2. Injection can be completed by a single, practiced individual and is well tolerated by both the pups and the dams. Pups experience minimal distress and recover quickly. Importantly, successful injection will result in global delivery of the agent administered. This protocol is appropriate for delivery of viral vectors, pharmaceutical agents or cells to newborn mice.

<table><tbody><tr><td>Thinpro insulin syringe</td><td>Terumo</td><td>SS30M3009</td><td>3/10 cc, 3/8&quot; needle, 30 G, 1 per mouse</td></tr><tr><td>Evans blue dye</td><td>Sigma-Aldrich</td><td>E2129</td><td>Dilute to 1% with 1x Phosphate Buffered Saline</td></tr><tr><td>Cotton tipped applicators</td><td>Fisher Scientific</td><td>23-400-101</td><td></td></tr><tr><td>Fiber optic light source</td><td>Fisher Scientific</td><td>12-562-36</td><td></td></tr><tr><td>Dissecting microscope</td><td></td><td></td><td></td></tr></tbody></table>

intravenous injections in neonatal mice

Intravenous injection is a clinically applicable manner to deliver therapeutics. For adult rodents and larger animals, intravenous injections are technically feasible and routine. However, some mouse models can have early onset of disease with a rapid progression that makes administration of potential therapies difficult. The temporal (or facial) vein is just anterior to the ear bud in mice and is clearly visible for the first two days after birth on either side of the head using a dissecting microscope. During this window, the temporal vein can be injected with volumes up to 50 &#956;l. The injection is safe and well tolerated by both the pups and the dams. A typical injection procedure is completed within 1-2 min, after which the pup is returned to the home cage. By the third postnatal day the vein is difficult to visualize and the injection procedure becomes technically unreliable. This technique has been used for delivery of adeno-associated virus (AAV) vectors, which in turn can provide almost body-wide, stable transgene expression for the life of the animal depending on the viral serotype chosen.

During a proper injection, the vein should momentarily turn clear, or blanch. If injecting dye the entire pup should turn blue within seconds. If an improper injection has occurred, there is often a concentrated subcutaneous bolus in the head or neck and injectant may leak out of the injection site. Improper injections may also result in the appearance of bruising around the throat. Pups that receive subcutaneous injections (i.e. the injection was not fully delivered in the vein) generally experience no ill side effects and routinely respond to treatment as the properly injected mice do.
Depending on the therapy delivered, successful injection can result in widespread delivery to the CNS and peripheral organs. When injecting self complimentary adeno-associated virus serotype 9 expressing green florescent protein (GFP) with a chicken &#946;-actin hybrid promoter (CB) (together referred to as &#8220;scAAV9 CB GFP&#8221;), transgene expression is found in glial cells and neurons across multiple brain regions and within the spinal cord (Figures 2A-2C). Intravascular injection of scAAV9 CB GFP also results in widespread expression throughout the periphery, with noticeable expression in heart and liver tissue (Figures 3A-3D).
<img alt="Figure 1" fo:content-width="5in" src="/files/ftp_upload/52037/52037fig1highres.jpg" width="500" /> 
Figure 1: (A) A makeshift injection platform made from an absorbant pad (&#8220;diaper&#8221;) wrapped around a Styrofoam rack from 50 ml conical packaging. The platform allows the investigator to rest their hand on the table adjacent to the platform. This allows the investigator to perform the injection at a flatter angle relative to the mouse pup. (B) Image showing pup immobilization between the fore and middle fingers. (C) Image showing a P2 pup after cryoanesthesia. The vein for injection is indicated by the white arrows. <a href="https://www.jove.com/files/ftp_upload/52037/52037fig1highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" fo:content-width="5in" src="/files/ftp_upload/52037/52037fig2highres.jpg" width="500" /> 
Figure 2: Central nervous system gene expression following neonate intravenous injection of self complementary AAV9 expressing green fluorescent protein (scAAV9 CB GFP). Postnatal day 1 (P1) mouse pups were intravenously injected with 1 x 1011 vector genomes (vg) of self-complementary (sc) scAAV9 CB GFP. Four weeks post injection, mice were sacrificed and perfused with 4% paraformaldehyde. Tissues were collected, sliced and stained for GFP expression. GFP expression is seen throughout the brain including the anterior striatum (A) through the pons and cerebellum (B). GFP positive cells are typically neurons and astrocytes. GFP expression is also detected in the spinal cord (C). Spinal motor neurons and dorsal root ganglia neurons are efficiently transduced using neonate IV delivery. GFP positive vasculature and astrocytes are also seen throughout the spinal grey matter. All scale bars = 200 &#956;m. <a href="https://www.jove.com/files/ftp_upload/52037/52037fig2highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" fo:content-width="5in" src="/files/ftp_upload/52037/52037fig3highres.jpg" width="500" /> 
Figure 3: GFP expression in peripheral organs following neonatal intravenous injection of self complementary AAV9 GFP (scAAV9 CB GFP). GFP immunofluorescence is detectable in the adult mouse heart (A) and liver (C) following neonatal intravenous injection of scAAV9 CB GFP. For comparison, GFP expression is absent in the heart (B) and liver (D) of uninjected mice. All scale bars = 100 &#181;m.

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Intravenous Injections in Neonatal Mice

Animal models of pediatric disease can experience early onset and aggressive disease progression. Clinically relevant therapy delivery to young mouse models can be technically difficult. This protocol describes a non-invasive intravenous injection method for newborn mice within the first two postnatal days of life.

Intravenous injection is a clinically applicable manner to deliver therapeutics. For adult rodents and larger animals, intravenous injections are ...

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58.1K Views.  Ohio State University. Animal models of pediatric disease can experience early onset and aggressive disease progression. Clinically relevant therapy delivery to young mouse models can be technically difficult. This protocol describes a non-invasive intravenous injection method for newborn mice within the first two postnatal days of life. 

Video: Intravenous Injections in Neonatal Mice

Delivery of Therapeutic Agents Through Intracerebroventricular (ICV) and Intravenous (IV) Injection in Mice

Despite the protective role that blood brain barrier plays in shielding the brain, it limits the access to the central nervous system (CNS) which most often results in failure of potential therapeutics designed for neurodegenerative disorders 1,2. Neurodegenerative diseases such as Spinal Muscular Atrophy (SMA), in which the lower motor neurons are affected, can benefit greatly from introducing the therapeutic agents into the CNS. The purpose of this video is to demonstrate two different injection paradigms to deliver therapeutic materials into neonatal mice soon after birth. One of these methods is injecting directly into cerebral lateral ventricles (Intracerebroventricular) which results in delivery of materials into the CNS through the cerebrospinal fluid 3,4. The second method is a temporal vein injection (intravenous) that can introduce different therapeutics into the circulatory system, leading to systemic delivery including the CNS 5. Widespread transduction of the CNS is achievable if an appropriate viral vector and viral serotype is utilized. Visualization and utilization of the temporal vein for injection is feasible up to postnatal day 6. However, if the delivered material is intended to reach the CNS, these injections should take place while the blood brain barrier is more permeable due to its immature status, preferably prior to postnatal day 2. The fully developed blood brain barrier greatly limits the effectiveness of intravenous delivery. Both delivery systems are simple and effective once the surgical aptitude is achieved. They do not require any extensive surgical devices and can be performed by a single person. However, these techniques are not without challenges. The small size of postnatal day 2 pups and the subsequent small target areas can make the injections difficult to perform and initially challenging to replicate.

Delivery of Therapeutic Agents Through Intracerebroventricular ICV and Intravenous IV Injection in Mice

This article demonstrates two very different methods of injection: 1) into the brain (intracerebroventricular) and 2) systemic (intravenous) to introduce the therapeutic agents into the central nervous system of neonatal mice.

Despite the protective role that blood brain barrier plays in shielding the brain, it limits the access to the central nervous system (CNS) which most ...

Medicine

Use of In vivo Imaging to Monitor the Progression of Experimental Mouse Cytomegalovirus Infection in Neonates

Human Cytomegalovirus (HCMV or HHV-5) is a life-threatening pathogen in immune-compromised individuals. Upon congenital or neonatal infection, the virus can infect and replicate in the developing brain, which may induce severe neurological damage, including deafness and mental retardation. Despite the potential severity of the symptoms, the therapeutic options are limited by the unavailability of a vaccine and the absence of a specific antiviral therapy. Furthermore, a precise description of the molecular events occurring during infection of the central nervous system (CNS) is still lacking since observations mostly derive from the autopsy of infected children. Several animal models, such as rhesus macaque CMV, have been developed and provided important insights into CMV pathogenesis in the CNS. However, despite its evolutionary proximity with humans, this model was limited by the intracranial inoculation procedure used to infect the animals and consistently induce CNS infection. Furthermore, ethical considerations have promoted the development of alternative models, among which neonatal infection of newborn mice with mouse cytomegalovirus (MCMV) has recently led to significant advances. For instance, it was reported that intraperitoneal injection of MCMV to Balb/c neonates leads to infection of neurons and glial cells in specific areas of the brain. These findings suggested that experimental inoculation of mice might recapitulate the deficits induced by HCMV infection in children. Nevertheless, a dynamic analysis of MCMV infection of neonates is difficult to perform because classical methodology requires the sacrifice of a significant number of animals at different time points to analyze the viral burden and/or immune-related parameters. To circumvent this bottleneck and to enable future investigations of rare mutant animals, we applied in vivo imaging technology to perform a time-course analysis of the viral dissemination in the brain upon peripheral injection of a recombinant MCMV expressing luciferase to C57Bl/6 neonates.

Use of In vivo Imaging to Monitor the Progression of Experimental Mouse Cytomegalovirus Infection in Neonates

Human Cytomegalovirus (HCMV) infection of neonates represents an important cause of mental retardation, yet the molecular events leading to virus-induced pathogenesis are still poorly understood. To investigate the dynamics of brain infection, we adapted whole-animal in vivo imaging to perform time-course analysis of neonates infected with a luciferase-recombinant virus.

Human Cytomegalovirus (HCMV or HHV-5) is a life-threatening  pathogen in immune-compromised individuals. Upon congenital or neonatal  infection, the virus ...

Immunology and Infection

Intravenous and Intra-amniotic In Utero Transplantation in the Murine Model

In utero transplantation (IUT) is a unique and versatile mode of therapy that can be used to introduce stem cells, viral vectors, or any other substances early in the gestation. The rationale behind IUT for therapeutic purposes is based on the small size of the fetus, the fetal immunologic immaturity, the accessibility and proliferative nature of the fetal stem or progenitor cells, and the potential to treat a disease or the onset of symptoms prior to birth. Taking advantage of these normal developmental properties of the fetus, the delivery of hematopoietic stem cells (HSC) via an IUT has the potential to treat congenital hematologic disorders such as sickle cell disease, without the required myeloablative or immunosuppressive conditioning required for postnatal HSC transplants. Similarly, the accessibility of progenitor cells in multiple organs during development potentially allows for a more efficient targeting of stem/progenitor cells following an IUT of viral vectors for gene therapy or genome editing. Additionally, IUT can be used to study normal developmental processes including, but not limited to, the development of immunologic tolerance. The murine model provides a valuable and affordable means to understanding the potential and limitations of IUT prior to pre-clinical large animal studies and an eventual clinical application. Here, we describe a protocol for performing an IUT in the murine fetus through intravenous and intra-amniotic routes. This protocol has been used successfully to elucidate the necessary conditions and mechanisms behind in utero hematopoietic stem cell transplantation, tolerance induction, and in utero gene therapy.

Intravenous and Intra-amniotic In Utero Transplantation in the Murine Model

We describe a protocol for performing an in utero transplantation (IUT) through intravenous and intra-amniotic routes of injection in the murine model. This protocol can be used to introduce cells, viral vectors, and other substances into the unique immune-tolerant fetal environment.

In utero transplantation (IUT) is a unique and versatile mode of therapy that can be used to introduce stem cells, viral vectors, or any other substances ...

Developmental Biology

Intracerebroventricular Viral Injection of the Neonatal Mouse Brain for Persistent and Widespread Neuronal Transduction

With the pace of scientific advancement accelerating rapidly, new methods are needed for experimental neuroscience to quickly and easily manipulate gene expression in the mouse brain. Here we describe a technique first introduced by Passini and Wolfe for direct intracranial delivery of virally-encoded transgenes into the neonatal mouse brain. In its most basic form, the procedure requires only an ice bucket and a microliter syringe. However, the protocol can also be adapted for use with stereotaxic frames to improve consistency for researchers new to the technique. The method relies on the ability of adeno-associated virus (AAV) to move freely from the cerebral ventricles into the brain parenchyma while the ependymal lining is still immature during the first 12-24 hr after birth. Intraventricular injection of AAV at this age results in widespread transduction of neurons throughout the brain. Expression begins within days of injection and persists for the lifetime of the animal. Viral titer can be adjusted to control the density of transduced neurons, while co-expression of a fluorescent protein provides a vital label of transduced cells. With the rising availability of viral core facilities to provide both off-the-shelf, pre-packaged reagents and custom viral preparation, this approach offers a timely method for manipulating gene expression in the mouse brain that is fast, easy, and far less expensive than traditional germline engineering.

Here we demonstrate a technique for widespread neuronal transduction by intraventricular injection of adeno-associated virus into the neonatal mouse brain. This method provides a rapid and easy way to attain lifelong expression of virally-delivered transgenes.

With the pace of scientific advancement accelerating rapidly, new methods are needed for experimental neuroscience to quickly and easily manipulate gene ...

Neuroscience

Intracerebroventricular and Intravascular Injection of Viral Particles and Fluorescent Microbeads into the Neonatal Brain

In the study on the pathogenesis of viral encephalitis, the infection method is critical. The first of the two main infectious routes to the brain is the hematogenous route, which involves infection of the endothelial cells and pericytes of the brain. The second is the intracerebroventricular (ICV) route. Once within the central nervous system (CNS), viruses may spread to the subarachnoid space, meninges, and choroid plexus via the cerebrospinal fluid. In experimental models, the earliest stages of CNS viral distribution are not well characterized, and it is unclear whether only certain cells are initially infected. Here, we have analyzed the distribution of cytomegalovirus (CMV) particles during the acute phase of infection, termed primary viremia, following ICV or intravascular (IV) injection into the neonatal mouse brain. In the ICV injection model, 5 &#181;l of murine CMV (MCMV) or fluorescent microbeads were injected into the lateral ventricle at the midpoint between the ear and eye using a 10-&#181;l syringe with a 27 G needle. In the IV injection model, a 1-ml syringe with a 35 G needle was used. A transilluminator was used to visualize the superficial temporal (facial) vein of the neonatal mouse. We infused 50 &#181;l of MCMV or fluorescent microbeads into the superficial temporal vein. Brains were harvested at different time points post-injection. MCMV genomes were detected using the in situ hybridization method. Fluorescent microbeads or green fluorescent protein expressing recombinant MCMV particles were observed by fluorescent microscopy. These techniques can be applied to many other pathogens to investigate the pathogenesis of encephalitis.

Here, we describe a simple method of intracerebroventricular and intravascular injection of viral particles or fluorescent microbeads into the neonatal mouse brain. The localization pattern of the virus and nanoparticles could be detected by microscopic evaluation or by in situ hybridization.

In the study on the pathogenesis of viral encephalitis, the infection method is critical. The first of the two main infectious routes to the brain is the ...

Performing Intracerebroventricular Injection in Mice Using a Free-Hand Approach

Free-Hand Intracerebroventricular Injections in Mice

The investigation of neuroendocrine systems often requires the delivery of drugs, viruses, or other experimental agents directly into the brains of mice. An intracerebroventricular (ICV) injection allows the widespread delivery of the experimental agent throughout the brain (particularly in the structures near the ventricles). Here, methods for making free-hand ICV injections in adult mice are described. By using visual and tactile landmarks on the heads of mice, injections into the lateral ventricles can be made rapidly and reliably. The injections are made with a glass syringe held in the experimenter&#39;s hand and placed at approximate distances from the landmarks. Thus, this technique does not require a stereotaxic frame. Furthermore, this technique requires only brief isoflurane anesthesia, which permits the subsequent assessment of mouse behavior and/or physiology in awake, freely behaving mice. Free-hand ICV injection is a powerful tool for the efficient delivery of experimental agents into the brains of living mice and can be combined with other techniques such as frequent blood sampling, neural circuit manipulation, or in vivo recording to investigate neuroendocrine processes.

Author Spotlight: Insights, Innovations, and Future Avenues in Reproductive Neurocontrol 

Here, a simple and rapid approach for performing intracerebroventricular injections in mice using a free-hand approach (that is, without a stereotaxic device) is described.

The investigation of neuroendocrine systems often requires the delivery of drugs, viruses, or other experimental agents directly into the brains of mice. ...

A Neonatal Rodent Model of Retroorbital Vein Injection

Intravenous (iv) injection is the most used route of drug administration in neonates in the clinical setting. Therefore, retroorbital vein injection is an important method for compound administration in research, where successful proof-of-concept studies can progress into much-needed neonatal clinical trials. Most intravenous studies in neonatal rodents use the superficial temporal/facial vein. However, retroorbital injection becomes unreliable in neonatal rodents older than 2 days after the skin darkens and the vein is no longer visible. In the present protocol, we describe the retroorbital injection of the venous sinus in both the neonatal mouse and rat at ages when the superficial temporal vein is no longer visible, but the eyes have not opened yet. Eye-opening facilitates retro-orbital injection by enabling the researcher to clearly see that they are not perforating the eye when inserting the needle. We demonstrate that this technique can be performed in a reliable and reproducible manner without adverse effects. Additionally, we show that it can be used in many studies, such as administering compounds to study neonatal brain injury.

This protocol aims to demonstrate a reproducible venous administration route that can be used in rats and mice throughout the neonatal period. This procedure is important for preclinical rodent studies that wish to mirror drug administration in neonatal care units primarily using intravenous administration.

Intravenous (iv) injection is the most used route of drug administration in neonates in the clinical setting. Therefore, retroorbital vein injection is an ...

A Comprehensive Protocol for Delivering Intrathecal Injections in Neonatal Mice

Intrathecal Injection of Newborn Mouse for Genome Editing and Drug Delivery

Intrathecal injection is a commonly employed procedure in both pediatric and adult clinics, serving as an effective means to administer medications and treatments. By directly delivering medications and treatments into the cerebrospinal fluid of the central nervous system, this method achieves higher localized drug concentrations while reducing systemic side-effects compared to other routes such as intravenous, subcutaneous, or intramuscular injections. Its importance extends beyond clinical settings, as intrathecal injection plays a vital role in preclinical studies focused on treating neurogenetic disorders in rodents and other large animals, including non-human primates. However, despite its widespread application, intrathecal injection in young, particularly neonatal pups, poses significant technical challenges due to their small size and fragile nature. Successful and reliable administration of intrathecal injections in newborn mice requires meticulous attention to detail and careful consideration of various factors. Thus, there is a crucial need for a standardized protocol that not only provides instructions but also highlights key technical considerations and good laboratory practices to ensure procedural consistency, as well as the safety and welfare of the animals.
To address this unmet need, we present a detailed and comprehensive protocol for performing intrathecal injections specifically in newborn pups on postnatal day 1 (P1). By following the step-by-step instructions, researchers can confidently perform intrathecal injections in neonatal pups, enabling the accurate delivery of drugs, antisense oligos, and viruses for gene replacement or genome editing-based treatments. Furthermore, the importance of adhering to good laboratory practices is emphasized to maintain the well-being of animals and ensure reliable experimental outcomes. This protocol aims to address the technical challenges associated with intrathecal injections in neonatal mice, ultimately facilitating advances in the field of neurogenetic research that aims to develop potential therapeutic interventions.

Author Spotlight: Intrathecal Injection &#8211; An Efficient and Reliable Delivery Method to Test the Efficacy of Gene Editing in Neonatal Mouse Brains

The present protocol outlines step-by-step instructions for performing intrathecal injections in neonatal mice for gene editing and drug delivery.

Intrathecal injection is a commonly employed procedure in both pediatric and adult clinics, serving as an effective means to administer medications and ...

Compound Administration III

Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN
There are many commonly used routes for compound administration in laboratory mice and rats. However, certain protocols may require the use of less commonly used routes, including intradermal, intranasal, and intracranial injections. Specialized training is essential for these procedures to be performed successfully. Justification for these routes may need to be provided to gain Institutional Animal Care and Use Committee (IACUC) approval.

Compound Administration in Rodents- Intradermal, Intranasal &amp; Intracranial Routes

Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN
There are many commonly used routes for compound ...

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An Intracerebroventricular Injection to Analyze Murine Cytomegalovirus Distribution in a Neonatal Mouse Brain

Source: Kawasaki, H., et al. <a href="https://app.jove.com/v/54164">Intracerebroventricular and Intravascular Injection of Viral Particles and Fluorescent Microbeads into the Neonatal Brain.</a> J. Vis. Exp. (2016).
This video demonstrates the intracerebroventricular injection process for studying murine cytomegalovirus (MCMV) distribution in the neonatal mouse brain. MCMV, engineered to express an enhanced green fluorescent protein (EGFP) for visibility, is injected into the lateral ventricle of a mouse pup&#39;s brain. The injected virus circulates through the cerebrospinal fluid, infecting cells in the periventricular region, including the marginal zone, choroid plexus, and subventricular zone.

1. ICV Injection of MCMV and Fluorescent Microbeads into Neonatal Mice

	Maintain normal pregnant ICR mice in a temperature-controlled facility under a 12 ...

Intravenous Injections in Neonatal Mice

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Chapters in this video

Delivery of Therapeutic Agents Through Intracerebroventricular (ICV) and Intravenous (IV) Injection in Mice

Use of In vivo Imaging to Monitor the Progression of Experimental Mouse Cytomegalovirus Infection in Neonates

Intravenous and Intra-amniotic In Utero Transplantation in the Murine Model

Intracerebroventricular Viral Injection of the Neonatal Mouse Brain for Persistent and Widespread Neuronal Transduction

Intracerebroventricular and Intravascular Injection of Viral Particles and Fluorescent Microbeads into the Neonatal Brain

Free-Hand Intracerebroventricular Injections in Mice

A Neonatal Rodent Model of Retroorbital Vein Injection

Intrathecal Injection of Newborn Mouse for Genome Editing and Drug Delivery

Compound Administration III

An Intracerebroventricular Injection to Analyze Murine Cytomegalovirus Distribution in a Neonatal Mouse Brain