The authors have no acknowledgements.

All animal experiments were performed in compliance with the German Animal Protection Law (TierSchG) and were approved by the local animal welfare committee (Lower Saxony State Office for Consumer Protection and Food Safety, Protocol TSA 14/1556). The minimal weight of mouse suitable for this model is 25 g.
1. Preoperative Preparations
NOTE: All procedures are carried out under clean, non-sterile conditions, with autoclaved instruments.
<ol>
	<li>Place 50-60 8-cm long propylene hollow fibers in parallel in a tube and connect with a T-adapter on both sides. Fill the space between the hollow fibers and the external branch of the T-adapter with glue.
	<ol>
		<li>Allow at least 24 h for the glue to harden. Cut the hollow fibers extending out from the T-adapter using a standard microtome and pull the silicone tube over to the connection sites.</li>
	</ol>
	</li>
	<li>Insert a 27 G metal needle (from a 26G branule)&#160;into a 2 Fr polyurethane cannula. Use a surgical blade and micro-scissors under a microscope (8-12X magnification) to make three to four fenestrations of about 0.15 cm each within the distal third of the cannula to assure optimal venous return flow.
	<ol>
		<li>Remove the wire when completed. Use cotton swabs for blunt dissection and retraction of structures. Use gauze swabs (5 x 5 cm2) to soak up excess fluid to prevent tissue dehydration.</li>
	</ol>
	</li>
	<li>Prepare the priming volume. For completion, add 30 IU of heparin per mL priming solution and 2.5% v/v of an 8.4% solution of NaHCO3 for buffering. Store this solution at 4 &#176;C until used.</li>
	<li>Fill the CPB circuit (i.e., pump, air trapper, tubing and both cannulas) with 850 &#181;L priming solution via the venous cannula. Once filled, keep the CPB circulating until the animal is ready for cannulation.</li>
</ol>
2. Animal Anesthesia
<ol>
	<li>To administer anesthesia, place the animal in an induction chamber under 2.5% v/v isoflurane/oxygen mixture. Confirm proper anesthesia by assessing pedal withdrawal reflex, tail pinch reflex, and eye blink reflex. Apply veterinary eye ointment to avoid eye dryness.</li>
	<li>Place the animal on a warming pad with temperature-regulating function. Measure body temperature with a probe inserted rectally and connected to the data acquisition system.</li>
	<li>After full anesthesia is achieved, intubate the animal orotracheally using a 20G plastic braunule, inserting it orally and pushing it into the trachea under visual control. Start mechanical ventilation using an isoflurane vaporizer connected to a mouse ventilator. Depending on the animal weight, adjust the ventilation so that a tidal volume of 250 - 350 &#181;L is achieved.</li>
	<li>To assure complete analgesia, inject 5 mg/kg animal bodyweight carprofen subcutaneously. It is recommended that isoflurane concentration be kept between 1.3 - 2.5% in oxygen. Isoflurane concentration may be manually adjusted depending on the stage of the procedure.</li>
</ol>
3. Surgical Procedures
<ol>
	<li>After full anesthesia and intubation is achieved, perform a midline skin incision to the neck with sharp fine scissors, separate muscles in a blunt fashion, and expose the right jugular vein and left carotid artery. During preparation, coagulate small vessels using a veterinary coagulator connected to bipolar forceps to ensure minimal blood loss.</li>
	<li>After preparation of the jugular vessels, cranially ligate the distal segment of the left common carotid artery to its bifurcation using 8-0 silk sutures.</li>
	<li>Connect the distal end of a 27 G cannula to the arterial inflow tubing using a silicone connector (0.5 mm ID, 1 mm OD), place 8-0 silk suture slip knots at the proximal segment of the artery, and insert the tip of the cannula into the carotid artery.</li>
	<li>After correct placement of the cannula tip, advance the cannula tip so that it lays 3 - 4 mm proximally to the aortic arch. Fix the cannula tip by securing with 8-0 silk knots.</li>
	<li>Using microsurgical forceps and scissors, perform blunt and sharp dissection, expose the right jugular vein by blunt preparation of tissue laterally to the sternocleidomastoid muscle, close to clavicle, and place an 8-0 silk knot at the distal end and an 8-0 loop at the proximal end.</li>
	<li>After ligation of the distal end of the jugular vein, place the tip of the venous cannula in the right jugular vein and progress towards the right atrium and secure using the silk knot. For optimal venous return, it may be necessary to advance the venous tip into the right ventricle.</li>
	<li>Once the correct cannula position is achieved, carry out systemic heparinization by adding 2.5 IU of heparin per gram of the animal bodyweight via direct intravenous injection into the jugular vein.</li>
	<li>For real-time invasive pressure monitoring, cannulate the left femoral artery. Expose the groin area and gently separate the common femoral artery from the femoral vein and femoral nerve under 25X magnification.
	<ol>
		<li>Ligate the distal part of the femoral artery. Temporarily occlude the proximal part with a slip-knot and make a small incision on the anterior wall using micro-forceps.</li>
		<li>Afterwards, insert a 1 Fr polyurethane cannula into the femoral artery and secure it with a silk 10-0 suture. This cannula is used to extract blood samples for blood gas analysis.</li>
	</ol>
	</li>
	<li>After successful placement of the arterial and venous cannulas, initiate cardiopulmonary bypass by turning on the pump. The time from intubation to starting of CPB is approximately 45 min. Start using a flow rate of 0.5 mL/min, depending on systemic pressure measurements, and increase blood flow within 2 min to full flow (4 - 6 mL/min) by increasing the pump speed.</li>
	<li>Under full monitoring, perform an upper sternotomy using sharp scissors starting from the manubrium and going 5 mm in the caudal direction. Coagulate the sternal edges immediately to avoid bleeding. Expose the aortic arch by pulling the right carotid artery in the cranial direction.</li>
	<li>For optimal control, circumferentially free the aortic arch from the thymus and surrounding tissue to facilitate clamping. Place a 8-0 silk loop around the ascending aorta. To place the cross clamp for cardioplegia, pull the silk loop in the cranial direction to better expose the ascending aorta.</li>
</ol>
4. Cardiopulmonary Bypass and Blood Gas Analysis
<ol>
	<li>For blood gas analysis (BGA), use glass capillary tubes to collect 60 - 90 &#181;L arterial blood via the femoral artery catheter.
	<ol>
		<li>Use a small clamp on the silicone tubing and detach the tubing from the catheter. Release pressure slowly on the clamp to allow controlled filling of the capillary tube.</li>
		<li>Reattach the silicone tube to the catheter. Insert capillary tubes into the blood gas analyzer for measurements at the following time points: 
		10 min after initiation of CPB with ventilation (BGA1) 
		after 25 min of CPB and 15 min of respiratory arrest (BGA2) 
		after 40 min of CPB and 30 min of respiratory arrest (BGA3) 
		after 55 min of CPB, 45 min of respiratory, and 20 min of cardiac arrest (BGA4)</li>
	</ol>
	</li>
	<li>Under stable CPB flow, initiate respiratory arrest by stopping ventilation.</li>
	<li>After termination of ventilation, set the warming pad to 28 &#186;C and&#160;start topically cooling the animal to 28 &#186;C body temperature within the first 20 min of respiratory arrest using gauze soaked in cold saline.</li>
	<li>Once a body temperature of 28 &#186;C is achieved, and after a total of 30 min of respiratory arrest, administer 0.3 mL of 7.45% KCl solution into the CPB circuit to initiate cardioplegia.</li>
	<li>For cross clamping of the aorta, pull the previously placed silk loop (step 3.10) in the cranial direction for better exposure and place a micro-serrefine clamp on the ascending part of the aorta.</li>
	<li>Perform a total of 60 min respiratory arrest and 30 min of cardiac arrest. Remove the micro-serrefine clamp from the ascending aorta to initiate reperfusion of the heart. Simultaneously, re-ventilate and warm the animal to 37 &#176;C.</li>
	<li>After reperfusion is completed and the animal has reached normothermia, terminate the CPB by turning off the pump and continue to monitor physiological measurements (e.g. body temperature, ECG, and invasive blood pressure) for 20 min.</li>
	<li>At the end of the experiment, exsanguinate the animal under full anesthesia (5% isoflurane) and collect blood and organs for further analysis14.</li>
</ol>

<ol>
	<li>Edmunds, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiopulmonary+Bypass+after+50+Years.">Cardiopulmonary Bypass after 50 Years.</a> N. Engl. J. Med. 351 (16), 1601-1603 (2004).</li><li>Goto, T., Maekawa, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+dysfunction+after+coronary+artery+bypass+surgery.">Cerebral dysfunction after coronary artery bypass surgery.</a> J. Anesth. 28 (2), 242-248 (2014).</li><li>Uysal, S., Reich, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurocognitive+outcomes+of+cardiac+surgery.">Neurocognitive outcomes of cardiac surgery.</a> J. Cardiothorac. Vasc. Anesth. 27 (5), 958-971 (2013).</li><li>Ballaux, P. K., Gourlay, T., Ratnatunga, C. P., Taylor, 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=A+literature+review+of+cardiopulmonary+bypass+models+for+rats.">A literature review of cardiopulmonary bypass models for rats.</a> Perfusion. 14 (6), 411-417 (1999).</li><li>Jungwirth, B., de Lange, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+cardiopulmonary+bypass:+development,+applications,+and+impact.">Animal models of cardiopulmonary bypass: development, applications, and impact.</a> Semin. Cardiothorac. Vasc. Anesth. 14 (2), 136-140 (2010).</li><li>G&#252;nzinger, R., 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+rat+model+of+cardiopulmonary+bypass+with+cardioplegic+arrest+and+hemodynamic+assessment+by+conductance+catheter+technique.">A rat model of cardiopulmonary bypass with cardioplegic arrest and hemodynamic assessment by conductance catheter technique.</a> Basic Res Cardiol. 102 (6), 508-517 (2007).</li><li>Waterbury, T., Clark, T. J., Niles, S., Farivar, R. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rat+model+of+cardiopulmonary+bypass+for+deep+hypothermic+circulatory+arrest.">Rat model of cardiopulmonary bypass for deep hypothermic circulatory arrest.</a> J. Thorac. Cardiovasc. Surg. 141 (6), 1549-1551 (2011).</li><li>Schnoering, 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+newly+developed+miniaturized+heart-lung+machine-expression+of+inflammation+in+a+small+animal+model.">A newly developed miniaturized heart-lung machine-expression of inflammation in a small animal model.</a> Artif. Organs. 34 (11), 911-917 (2010).</li><li>Kim, 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=The+responses+of+tissues+from+the+brain,+heart,+kidney,+and+liver+to+resuscitation+following+prolonged+cardiac+arrest+by+examining+mitochondrial+respiration+in+rats.">The responses of tissues from the brain, heart, kidney, and liver to resuscitation following prolonged cardiac arrest by examining mitochondrial respiration in rats.</a> Oxid. Med. Cell. Longev. 2016, (2016).</li><li>Shappell, S. B., Gurpinar, T., Lechago, J., Suki, W. N., Truong, L. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+obstructive+uropathy+in+severe+combined+immunodeficient+(SCID)+mice:+lymphocyte+infiltration+is+not+required+for+progressive+tubulointerstitial+injury.">Chronic obstructive uropathy in severe combined immunodeficient (SCID) mice: lymphocyte infiltration is not required for progressive tubulointerstitial injury.</a> J. Am. Soc. Nephrol. 9 (6), 1008-1017 (1998).</li><li>Majzoub, J. A., Muglia, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Knockout+mice.">Knockout mice.</a> N. Engl. J. Med. , 904-907 (1996).</li><li>Houser, S. R., 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=Animal+Models+of+Heart+Failure+A+Scientific+Statement+From+the+American+Heart+Association.">Animal Models of Heart Failure A Scientific Statement From the American Heart Association.</a> Circ. Res. 111 (1), 131-150 (2012).</li><li>Russell, J. C., Proctor, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+animal+models+of+cardiovascular+disease:+tools+for+the+study+of+the+roles+of+metabolic+syndrome,+dyslipidemia,+and+atherosclerosis.">Small animal models of cardiovascular disease: tools for the study of the roles of metabolic syndrome, dyslipidemia, and atherosclerosis.</a> Cardiovasc. Pathol. 15 (6), 318-330 (2006).</li><li>Iurascu-Gagea, M., Craig, S., Suckow, M. A., Stevens, K. A., Wilson, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Euthanasia+and+necropsy.">Euthanasia and necropsy.</a> The laboratory rabbit, guinea pig, hamster, and other rodents. , 117-141 (2012).</li></ol>

The authors have nothing to disclose.

We have developed a fully-functioning clinically-relevant model of CPB in a mouse. With more than thirty strains of mice having cardiovascular diseases, our model could be a starting point for development of new prospective protocols related to CPB. Moreover, due to the plethora of mouse-specific reagents and knockout-out mice, this model can not only replace the current rat model of CPB but will facilitate dissection of the molecular mechanisms involved in CPB-related organ damage. To date, CPB has not been applied in m...

Since the introduction of cardiopulmonary bypass (CPB) into the clinic, it has played an essential role in cardiac surgery1. In modern cardiac surgery, prolonged CPB time is essential to perform extensive aortic reconstructions and combined procedures. Although technological advances have been tremendous, the use of extracorporal circulation is associated with intra- and postoperative systemic and local organ damage2,3.
Large animal models have been developed to investigate the role of CPB on physiological processes4,5. Although these models have provided insight into some of the CPB associated complications, they are extremely costly and molecular tools (e.g., antibodies) are very limited. A more cost-efficient alternative has been developed in small animals. Since their development, multiple studies have been conducted to optimize a CPB model in rats and rabbits5,6,7,8,9. These models provide a good basis for measurements of pathophysiological disease processes; however, they are still insufficient to investigate cellular and humoral immunology due to the lack of relevant antibodies and reagents. This impairs their role in this field of research.
We have recently developed a mouse model of CPB. Due to a wide variety of mouse-specific reagents and genetically-modified mice, mouse models are in general the model of choice for physiological, molecular, and immunological research10,11. Therefore, our model will facilitate the study of CPB in relation to various comorbidities as there are many mice strains available with clinically-relevant diseases12,13. Accordingly, this paper describes, in detail, how to perform CPB in mice. Oxygen and hemodynamic parameters are closely monitored after deep respiratory and circulatory arrest.

<table border="0" cellpadding="0" cellspacing="0" width="1191">
	<tbody>
		<tr height="23">
			<td height="23" style="height:23px;width:297px;">Sterofundin</td>
			<td style="width:279px;">B.Braun Petzold GmbH</td>
			<td style="width:181px;">PZN:8609189</td>
			<td style="width:435px;">priming volume, 1:1 with Tetraspan</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:297px;">Tetraspan 6% HES Solution</td>
			<td style="width:279px;">B. Braun Melsungen AG</td>
			<td style="width:181px;">PZN: 05565416</td>
			<td>priming volume, 1:1 with Sterofundin</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:297px;">Heparin Natrium 25.000</td>
			<td style="width:279px;">Ratiopharm GmbH</td>
			<td style="width:181px;">PZN: 3029843</td>
			<td>2.5 IU per ml of priming solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:297px;">NaHCO3 8,4% Solution</td>
			<td style="width:279px;">B. Braun Melsungen AG</td>
			<td style="width:181px;">PZN: 1579775</td>
			<td>3% in priming solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:297px;">KCL 7,45 % Solution</td>
			<td style="width:279px;">B. Braun Melsungen AG</td>
			<td style="width:181px;">PZN: 2418577</td>
			<td>0.1 ml for cardioplegia</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:297px;">Carprofen</td>
			<td style="width:279px;">Zoetis Inc., USA</td>
			<td>PZN:00289615 08859153</td>
			<td>5 mg/kg/BW</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:297px;">1 Fr PU Catheter</td>
			<td style="width:279px;">Instechlabs INC., USA</td>
			<td style="width:181px;">C10PU-MCA1301</td>
			<td>carotid artery</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:297px;">2 Fr PU Catheter</td>
			<td style="width:279px;">Instechlabs INC., USA</td>
			<td style="width:181px;">C20PU-MJV1302</td>
			<td>jugular vein</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vasofix Safety catheter 20G</td>
			<td style="width:279px;">B.Braun Medical</td>
			<td style="width:181px;">4268113S-01</td>
			<td>orotracheal intubation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:297px;">8-0 Silk suture braided</td>
			<td>Ashaway Line &#38; Twine Mfg. Co., USA</td>
			<td style="width:181px;">75290</td>
			<td>ligature</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:297px;">Isoflurane</td>
			<td style="width:279px;">Piramal Critical Care Deutschland GmbH</td>
			<td style="width:181px;">PZN:9714675</td>
			<td>narcosis</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CLINITUBES blood capillaries</td>
			<td style="width:279px;">Radiomed GmbH</td>
			<td style="width:181px;">51750132</td>
			<td>blood sampling 60 - 95 microliter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Spring Scissors - 6mm Blades</td>
			<td>Fine Science Tools GmbH</td>
			<td style="width:181px;">15020-15</td>
			<td>instruments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Spring Scissors - 2mm Blades</td>
			<td>Fine Science Tools GmbH</td>
			<td style="width:181px;">15000-03</td>
			<td>instruments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Halsted-Mosquito Hemostat</td>
			<td>Fine Science Tools GmbH</td>
			<td style="width:181px;">13009-12</td>
			<td>instruments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dumont #55 Forceps</td>
			<td>Fine Science Tools GmbH</td>
			<td style="width:181px;">11295-51</td>
			<td>instruments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Castroviejo Micro Needle Holder - 9cm</td>
			<td>Fine Science Tools GmbH</td>
			<td style="width:181px;">12060-02</td>
			<td>instruments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Micro Serrefines</td>
			<td>Fine Science Tools GmbH</td>
			<td>18555-01</td>
			<td>instruments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bulldog Serrefine</td>
			<td>Fine Science Tools GmbH</td>
			<td style="width:181px;">18050-28</td>
			<td>instruments</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:297px;">MiniVent Ventilator for Mice (Model 845)</td>
			<td style="width:279px;">Harvard Apparatus</td>
			<td style="width:181px;">73-0044</td>
			<td>mechanical ventilation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:297px;">Isoflurane Vaporizer Drager 19.1</td>
			<td style="width:279px;">Dr&#228;gerwerk AG &#38; Co. KGaA</td>
			<td style="width:181px;"></td>
			<td>anesthesia 1.3 -2.5%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PowerLab data acquisition device 4/35</td>
			<td>ADInstruments Ltd, New Zealand</td>
			<td style="width:181px;">PL3504</td>
			<td>invasive pressure, ECG, temperature</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ABL 800 Flex</td>
			<td>Radiometer GmbH</td>
			<td style="width:181px;"></td>
			<td>blood gas analysis</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:297px;">NMRI mice</td>
			<td style="width:279px;">Charles River Laboratories</td>
			<td style="width:181px;">Crl:NMRI(Han)</td>
			<td>male, 30-35 g, 12 weeks old, housed at least 1 week before the experiment</td>
		</tr>
	</tbody>
</table>

cardiopulmonary bypass in a mouse model: a novel approach

As prolonged cardiopulmonary bypass becomes more essential during cardiac interventions, an increasing clinical demand arises for procedure optimization and for minimizing organ damage resulting from prolonged extracorporal circulation. The goal of this paper was to demonstrate a fully functional and clinically relevant model of cardiopulmonary bypass in a mouse. We report on the device design, perfusion circuit optimization, and microsurgical techniques. This model is an acute model, which is not compatible with survival due to the need for multiple blood drawings. Because of the range of tools available for mice (e.g., markers, knockouts, etc.), this model will facilitate investigation into the molecular mechanisms of organ damage and the effect of cardiopulmonary bypass in relation to other comorbidities.

This protocol describes the perfusion circuit, surgical procedures, and monitoring of physiological parameters during CPB of a mouse. When performed by an adequately skilled microsurgeon, the results are consistently and reproducibly obtained.
To maintain adequate tissue perfusion, the mean arterial pressure is always kept between 40 and 60 mmHg by adjusting the CPB blood flow and adding of extra volume. Depending on the weight ...

Watch this Scientific Journal Video about Cardiopulmonary Bypass in a Mouse Model: A Novel Approach at JoVE.com

Cardiopulmonary Bypass in a Mouse Model: A Novel Approach

This paper describes how to perform cardiopulmonary bypass in mice. This novel model will facilitate the investigation of the molecular mechanisms involved in organ damage.

As prolonged cardiopulmonary bypass becomes more essential during cardiac interventions, an increasing clinical demand arises for procedure optimization ...

cardiopulmonary-bypass-in-a-mouse-model-a-novel-approach

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10.8K Views.  Hannover Medical School. This paper describes how to perform cardiopulmonary bypass in mice. This novel model will facilitate the investigation of the molecular mechanisms involved in organ damage.

Video: Cardiopulmonary Bypass in a Mouse Model: A Novel Approach

Vascular Occlusion Training for Inclusion Body Myositis: A Novel Therapeutic Approach

Inclusion body myositis (IBM) is a rare idiopathic inflammatory myopathy. It is known to produces remarkable muscle weakness and to greatly compromise function and quality of life. Moreover, clinical practice suggests that, unlike other inflammatory myopathies, the majority of IBM patients are not responsive to treatment with immunosuppressive or immunomodulatory drugs to counteract disease progression1. Additionally, conventional resistance training programs have been proven ineffective in restoring muscle function and muscle mass in these patients2,3. Nevertheless, we have recently observed that restricting muscle blood flow using tourniquet cuffs in association with moderate intensity resistance training in an IBM patient produced a significant gain in muscle mass and function, along with substantial benefits in quality of life4. Thus, a new non-pharmacological approach for IBM patients has been proposed. Herein, we describe the details of a proposed protocol for vascular occlusion associated with a resistance training program for this population.

The present article presents the details pertaining to the application of resistance training associated to vascular occlusion in IBM patients.

Inclusion body myositis (IBM) is a rare idiopathic inflammatory myopathy. It is known to produces remarkable muscle weakness and to greatly compromise ...

Bronchial Thermoplasty:  A Novel Therapeutic Approach to Severe Asthma

Bronchial thermoplasty is a non-drug procedure for severe persistent asthma that delivers thermal energy to the airway wall in a precisely controlled manner to reduce excessive airway smooth muscle. Reducing airway smooth muscle decreases the ability of the airways to constrict, thereby reducing the frequency of asthma attacks. Bronchial thermoplasty is delivered by the Alair System and is performed in three outpatient procedure visits, each scheduled approximately three weeks apart. The first procedure treats the airways of the right lower lobe, the second treats the airways of the left lower lobe and the third and final procedure treats the airways in both upper lobes. After all three procedures are performed the bronchial thermoplasty treatment is complete.
Bronchial thermoplasty is performed during bronchoscopy with the patient under moderate sedation. All accessible airways distal to the mainstem bronchi between 3 and 10 mm in diameter, with the exception of the right middle lobe, are treated under bronchoscopic visualization. Contiguous and non-overlapping activations of the device are used, moving from distal to proximal along the length of the airway, and systematically from airway to airway as described previously. Although conceptually straightforward, the actual execution of bronchial thermoplasty is quite intricate and procedural duration for the treatment of a single lobe is often substantially longer than encountered during routine bronchoscopy. As such, bronchial thermoplasty should be considered a complex interventional bronchoscopy and is intended for the experienced bronchoscopist. Optimal patient management is critical in any such complex and longer duration bronchoscopic procedure. This article discusses the importance of careful patient selection, patient preparation, patient management, procedure duration, postoperative care and follow-up to ensure that bronchial thermoplasty is performed safely.
Bronchial thermoplasty is expected to complement asthma maintenance medications by providing long-lasting asthma control and improving asthma-related quality of life of patients with severe asthma. In addition, bronchial thermoplasty has been demonstrated to reduce severe exacerbations (asthma attacks) emergency rooms visits for respiratory symptoms, and time lost from work, school and other daily activities due to asthma.

Bronchial thermoplasty is a non-drug procedure for severe persistent asthma that delivers thermal energy to the airway wall in a precisely controlled manner to reduce excessive airway smooth muscle. Reducing airway smooth muscle decreases the ability of the airways to constrict, thereby reducing the frequency of asthma attacks.

Bronchial thermoplasty is a non-drug procedure for severe persistent asthma that delivers thermal energy to the airway wall in a precisely controlled ...

Multi-photon Imaging of Tumor Cell Invasion in an Orthotopic Mouse Model of Oral Squamous Cell Carcinoma

Loco-regional invasion of head and neck cancer is linked to metastatic risk and presents a difficult challenge in designing and implementing patient management strategies. Orthotopic mouse models of oral cancer have been developed to facilitate the study of factors that impact invasion and serve as model system for evaluating anti-tumor therapeutics. In these systems, visualization of disseminated tumor cells within oral cavity tissues has typically been conducted by either conventional histology or with in vivo bioluminescent methods. A primary drawback of these techniques is the inherent inability to accurately visualize and quantify early tumor cell invasion arising from the primary site in three dimensions. Here we describe a protocol that combines an established model for squamous cell carcinoma of the tongue (SCOT) with two-photon imaging to allow multi-vectorial visualization of lingual tumor spread. The OSC-19 head and neck tumor cell line was stably engineered to express the F-actin binding peptide LifeAct fused to the mCherry fluorescent protein (LifeAct-mCherry). Fox1nu/nu mice injected with these cells reliably form tumors that allow the tongue to be visualized by ex-vivo application of two-photon microscopy. This technique allows for the orthotopic visualization of the tumor mass and locally invading cells in excised tongues without disruption of the regional tumor microenvironment. In addition, this system allows for the quantification of tumor cell invasion by calculating distances that invaded cells move from the primary tumor site. Overall this procedure provides an enhanced model system for analyzing factors that contribute to SCOT invasion and therapeutic treatments tailored to prevent local invasion and distant metastatic spread. This method also has the potential to be ultimately combined with other imaging modalities in an in vivo setting.

A comprehensive overview of the techniques involved in generating a mouse model of oral cancer and quantitative monitoring of tumor invasion within the tongue through multi-photon microscopy of labeled cells is presented. This system can serve as a useful platform for the molecular assessment and drug efficacy of anti-invasive compounds.

Loco-regional invasion of head and neck cancer is linked to metastatic risk and presents a difficult challenge in designing and implementing patient ...

Normothermic Cardiac Arrest and Cardiopulmonary Resuscitation: A Mouse Model of Ischemia-Reperfusion Injury

Acute Kidney Injury (AKI) is a common, highly lethal, complication of critical illness which has a high mortality1-4 and which is most 
frequently caused by whole-body hypoperfusion.5,6 Successful reproduction of whole-body hypoperfusion in rodent models has been fraught with 
difficulty.7-9,9,10 Models which employ focal ischemia have repeatedly demonstrated results which do not translate to the clinical setting, and larger 
animal models which allow for whole body hypoperfusion lack access to the full toolset of genetic manipulation possible in the mouse.11,12 However, in recent 
years a mouse model of cardiac arrest and cardiopulmonary resuscitation has emerged which can be adapted to model AKI.13 This model reliably reproduces 
physiologic, functional, anatomic, and histologic outcomes seen in clinical AKI, is rapidly repeatable, and offers all of the significant advantages of a murine surgical 
model, including access to genetic manipulative techniques, low cost relative to large animals, and ease of use. Our group has developed extensive experience 
with use of this model to assess a number of organ-specific outcomes in AKI.14,15

A powerful model for perioperative and critical care related acute kidney injury is presented. Using whole body hypoperfusion induced by cardiac arrest it is possible to nearly replicate the histologic and functional changes of clinical AKI.

Acute Kidney Injury (AKI) is a common, highly lethal, complication of critical illness which has a high mortality1-4 and which is most 
frequently caused ...

Roux-en-Y Gastric Bypass Operation in Rats

Currently, the most effective therapy for the treatment of morbid obesity to induce significant and maintained body weight loss with a proven mortality benefit is bariatric surgery1,2. Consequently, there has been a steady rise in the number of bariatric operations done worldwide in recent years with the Roux-en-Y gastric bypass (gastric bypass) being the most commonly performed operation3. Against this background, it is important to understand the physiological mechanisms by which gastric bypass induces and maintains body weight loss. These mechanisms are yet not fully understood, but may include reduced hunger and increased satiation4,5, increased energy expenditure6,7, altered preference for food high in fat and sugar8,9, altered salt and water handling of the kidney10 as well as alterations in gut microbiota11. Such changes seen after gastric bypass may at least partly stem from how the surgery alters the hormonal milieu because gastric bypass increases the postprandial release of peptide-YY (PYY) and glucagon-like-peptide-1 (GLP-1), hormones that are released by the gut in the presence of nutrients and that reduce eating12.
During the last two decades numerous studies using rats have been carried out to further investigate physiological changes after gastric bypass. The gastric bypass rat model has proven to be a valuable experimental tool not least as it closely mimics the time profile and magnitude of human weight loss, but also allows researchers to control and manipulate critical anatomic and physiologic factors including the use of appropriate controls. Consequently, there is a wide array of rat gastric bypass models available in the literature reviewed elsewhere in more detail 13-15. The description of the exact surgical technique of these models varies widely and differs e.g. in terms of pouch size, limb lengths, and the preservation of the vagal nerve. If reported, mortality rates seem to range from 0 to 35%15. Furthermore, surgery has been carried out almost exclusively in male rats of different strains and ages. Pre- and postoperative diets also varied significantly.
Technical and experimental variations in published gastric bypass rat models complicate the comparison and identification of potential physiological mechanisms involved in gastric bypass. There is no clear evidence that any of these models is superior, but there is an emerging need for standardization of the procedure to achieve consistent and comparable data. This article therefore aims to summarize and discuss technical and experimental details of our previously validated and published gastric bypass rat model.

Numerous studies using gastric bypass rat models have been recently conducted to uncover the underlying physiological mechanisms of Roux-en-Y gastric bypass operations. This article aims to demonstrate and discuss the technical and experimental details of our published gastric bypass rat model to understand advantages and limitations of this experimental tool.

Currently, the most effective therapy for the treatment of morbid obesity to induce significant and maintained body weight loss with a proven mortality ...

A Novel Surgical Approach for Intratracheal Administration of Bioactive Agents in a Fetal Mouse Model

Prenatal pulmonary delivery of cells, genes or pharmacologic agents could provide the basis for new therapeutic strategies for a variety of genetic and acquired diseases. Apart from congenital or inherited abnormalities with the requirement for long-term expression of the delivered gene, several non-inherited perinatal conditions, where short-term gene expression or pharmacological intervention is sufficient to achieve therapeutic effects, are considered as potential future indications for this kind of approach. Candidate diseases for the application of short-term prenatal therapy could be the transient neonatal deficiency of surfactant protein B causing neonatal respiratory distress syndrome1,2 or hyperoxic injuries of the neonatal lung3. Candidate diseases for permanent therapeutic correction are Cystic Fibrosis (CF)4, genetic variants of surfactant deficiencies5 and &alpha;1-antitrypsin deficiency6.
Generally, an important advantage of prenatal gene therapy is the ability to start therapeutic intervention early in development, at or even prior to clinical manifestations in the patient, thus preventing irreparable damage to the individual. In addition, fetal organs have an increased cell proliferation rate as compared to adult organs, which could allow a more efficient gene or stem cell transfer into the fetus. Furthermore, in utero gene delivery is performed when the individual's immune system is not completely mature. Therefore, transplantation of heterologous cells or supplementation of a non-functional or absent protein with a correct version should not cause immune sensitization to the cell, vector or transgene product, which has recently been proven to be the case with both cellular and genetic therapies7.
In the present study, we investigated the potential to directly target the fetal trachea in a mouse model. This procedure is in use in larger animal models such as rabbits and sheep8, and even in a clinical setting9, but has to date not been performed before in a mouse model. When studying the potential of fetal gene therapy for genetic diseases such as CF, the mouse model is very useful as a first proof-of-concept because of the wide availability of different transgenic mouse strains, the well documented embryogenesis and fetal development, less stringent ethical regulations, short gestation and the large litter size.
Different access routes have been described to target the fetal rodent lung, including intra-amniotic injection10-12, (ultrasound-guided) intrapulmonary injection13,14 and intravenous administration into the yolk sac vessels15,16 or umbilical vein17. Our novel surgical procedure enables researchers to inject the agent of choice directly into the fetal mouse trachea which allows for a more efficient delivery to the airways than existing techniques18.

We developed a novel surgical approach for intratracheal administration of bioactive agents into the mouse fetus. The delivery route is more efficient in targeting the fetal mouse lungs than the commonly used intra-amniotic injection. This procedure has to date not been described in a mouse model.

Prenatal pulmonary delivery of cells, genes or pharmacologic agents could provide the basis for new therapeutic strategies for a variety of genetic and ...

Evaluation of a Novel Laser-assisted Coronary Anastomotic Connector - the Trinity Clip - in a Porcine Off-pump Bypass Model

To simplify and facilitate beating heart (i.e., off-pump), minimally invasive coronary artery bypass surgery, a new coronary anastomotic connector, the Trinity Clip, is developed based on the excimer laser-assisted nonocclusive anastomosis technique. The Trinity Clip connector enables simplified, sutureless, and nonocclusive connection of the graft to the coronary artery, and an excimer laser catheter laser-punches the opening of the anastomosis. Consequently, owing to the complete nonocclusive anastomosis construction, coronary conditioning (i.e., occluding or shunting) is not necessary, in contrast to the conventional anastomotic technique, hence simplifying the off-pump bypass procedure. Prior to clinical application in coronary artery bypass grafting, the safety and quality of this novel connector will be evaluated in a long-term experimental porcine off-pump coronary artery bypass (OPCAB) study. In this paper, we describe how to evaluate the coronary anastomosis in the porcine OPCAB model using various techniques to assess its quality. Representative results are summarized and visually demonstrated.

This paper describes a novel nonocclusive coronary anastomotic connector in a porcine off-pump coronary artery bypass (OPCAB) model. This easy-to-use coronary connector has intrinsic potential to facilitate minimally invasive OPCAB surgery.

To simplify and facilitate beating heart (i.e., off-pump), minimally invasive coronary artery bypass surgery, a new coronary anastomotic connector, the ...

A Novel Approach for the Administration of Medications and Fluids in Emergency Scenarios and Settings

The available routes of administration commonly used for medications and fluids in the acute care setting are generally limited to oral, intravenous, or intraosseous routes, but in many patients, particularly in the emergency or critical care settings, these routes are often unavailable or time-consuming to access. A novel device is now available that offers an easy route for administration of medications or fluids via rectal mucosal absorption (also referred to as proctoclysis in the case of fluid administration and subsequent absorption). Although originally intended for the palliative care market, the utility of this device in the emergency setting has recently been described. Specifically, reports of patients being treated for dehydration, alcohol withdrawal, vomiting, fever, myocardial infarction, hyperthyroidism, and cardiac arrest have shown success with administration of a wide variety of medications or fluids (including water, aspirin, lorazepam, ondansetron, acetaminophen, methimazole, and buspirone). Device placement is straightforward, and based on the observation of expected effects from the medication administrations, absorption is rapid. The rapidity of absorption kinetics are further demonstrated in a recent report of the measurement of phenobarbital pharmacokinetics. We describe here the placement and use of this device, and demonstrate methods of pharmacokinetic measurements of medications administered by this method.

This study presents a novel device that offers an easy route to quickly provide medications and fluids in patients with limited or difficult IV access. This small-diameter device is placed in the distal third of the rectum, allowing for ongoing medication and fluids administration.

The available routes of administration commonly used for medications and fluids in the acute care setting are generally limited to oral, intravenous, or ...

Vein Interposition Model: A Suitable Model to Study Bypass Graft Patency

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. Research models for bypass graft failure are essential for a better understanding of pathobiological and pathophysiological processes during graft patency loss. Large animal models, such as pigs or sheep, resemble human anatomical structures but require special facilities and equipment. This video describes a rat vein interposition model to investigate vein graft patency loss. Rats are inexpensive and easy to handle. Compared to mouse models, the convenient size of rats permits better operability and enables a sufficient amount of material to be obtained for further diverse analysis. In brief, the inferior epigastric vein of a donor rat is harvested and used to replace a segment of the femoral artery. Anastomosis is conducted via single stitches and sealed with fibrin glue. Graft patency can be monitored non-invasively using duplex sonography. Myointimal hyperplasia, which is the main cause for graft patency loss, develops progressively over time and can be calculated from histological cross sections.

This video demonstrates a model to study the development of myointimal hyperplasia after venous interposition surgery in rats.

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...