The authors would like to acknowledge the Cincinnati Children&#8217;s Hospital Division of Veterinary Services for their assistance. This manuscript was supported by the National Institutes of Health K12 HD028827. Anna Perl PhD taught the authors this surgical procedure.

NOTE: Animal use statement: All procedures in this study were conducted with approval and following the guidelines of the Institutional Animal Use and Care Committee (IACUC) at Cincinnati Children&#8217;s Hospital. Eight week-old C57BL/6J male mice were obtained from Jackson Laboratories (Bar Harbor, ME) and allowed to acclimate for one week prior to use. Up until surgery, animals were housed in a pathogen-free barrier facility and provided autoclaved chow and filtered water ad libdium. Each mouse cage was supplied with a dedicated air and water, and rooms were maintained on a 12 hr day-night cycle. Following recovery from surgery, mice were maintained in cages with filtered tops, provided autoclaved chow ad libidum, and provided filtered water from a water bottle.
1. Preparation of Instruments
<ol>
	<li>Make 6 skin retractors using paper clips and pins. Twist straightened paper clips on the shanks of paper pins, leave a 5 cm straight steel wire on one end and make a single 0.5 cm &#8220;U&#8221; shaped hook at the end of the wire.</li>
	<li>Make some 15 x 15 cm square surgical drapes using plastic wrap. Prepare one dressing per mouse. Put a paper tower in between each wrap.</li>
	<li>Sterilize all surgical tools along with a stack of 12 x 12 inch cork tiles, gauze, and cotton-tipped swabs.</li>
</ol>
2. Mouse Preparation
<ol>
	<li>Induce anesthesia with 2% isoflurane. Weigh animal.</li>
	<li>In a dedicated surgical preparation area shave left thorax and neck area with electrical shaver.</li>
	<li>Apply a drop of the artificial tear ointment to the mouse&#8217;s eyes.</li>
	<li>Decontaminate neck and left thorax with chlorhexidine and isopropyl alcohol. Repeat twice more.</li>
</ol>
3. Mouse Oro-tracheal Intubation and Mechanical Ventilation
<ol>
	<li>Have a non-sterile surgical technician place the mouse supine in the pre-warmed surgical area.</li>
	<li>Confirm depth of anesthesia by documenting lack of a response to paw pinch.</li>
	<li>After washing hands and donning surgical attire, mask, and hat, don sterile surgical gloves.</li>
	<li>After draping and using aseptic technique, make a 1 cm vertical incision over the anterior mid-neck to expose the larynx. Lightly retract the strap muscles with curved, serrated 10 cm forceps and expose the larynx and trachea by spreading the strap muscles with the tip of a straight scissors.</li>
	<li>Orally insert a 22 G blunt-tip angiocatheter into the mid-trachea (Figure 1A) and visually confirm placement (Figure 1B).&#160;Maintain anesthesia and ventilate using 1-3% isoflurane through rodent ventilator (225 &#181;l per stroke; 200 stokes per min). Employ a pressure limit of 15 cm H2O.</li>
</ol>
4. Mouse Pneumonectomy
<ol>
	<li>Lay the mouse in the right lateral decubitus position with the mouse&#8217;s back facing the operator (left side up). Use a self-sealing plastic wrap as a sterile drape. Cutting through the drape, use blunt tipped curved scissors to make a 2 cm long cut parallel to the ribs at the 4th and 5th intercostal space. Insert the blunt tip curved scissors and dissect the skin away from the underlying ribs and intercostal muscles.</li>
	<li>Retract the skin with four retractors to expose a square 1.5 x 1.5 cm surgical window (Figure 2A). Secure the retractors to the cork board.</li>
	<li>Dissect down to ribs using curved forceps, and use one tip of the curved forceps to enter the thoracic cavity.</li>
	<li>Using the blunt tip micro-scissors, use the lower blade to enter the thoracic cavity. Make a 0.5 cm incision between the ribs and repeat in the opposite direction.</li>
	<li>Using the two remaining retractors, open the thorax in the anterior-posterior axis and the secure the retractors to the cork board (Figure 2B).</li>
	<li>Using curved blunt-tipped forceps in the left hand, grasp the left lung and displace the upper portion of the left lung laterally and inferiorly through the thoracotomy until the left pulmonary artery and bronchus are exposed (Figure 3A,B).</li>
	<li>Holding the loaded titanium vascular microclip applicator in the right hand with the body of the applicator in the palm and curved tip pointing away from the palm (Figure 3C), slide the applicator tip into the thorax along the curvature of the posterior aspect of the left lung and clip the left bronchus and pulmonary artery (Figure 3D).</li>
	<li>Remove the applicator but keep the left lung retracted. Grasp the blunt tip micro-scissors with the right hand and cut the bronchus and pulmonary artery distal to the clip and remove left lung (Figure 3E).</li>
	<li>Remove the rib retractors.</li>
	<li>Use the curved blunt forceps to pinch up 1 cm of skin inferior to the incision but above the level of the diaphragm and insert a 24 G angiocatheter through the skin and into the left thoracic cavity (Figure&#160;4A,B).</li>
	<li>Use 5-0 prolene suture to place two interrupted sutures around the 4th and 5th ribs to close the thoracic cavity.</li>
	<li>Remove the skin retractors. Use two sets of forceps to approximate the skin along the length of the incision and glue the skin closed.</li>
	<li>Connect a 3 ml luer-lock syringe to the angiocatheter and remove residual air by applying gentle suction and withdrawing the angiocatheter.</li>
	<li>Glue the neck incision closed using two sets of forceps as before.</li>
</ol>
5. Mouse Sham Pneumonectomy
<ol>
	<li>Expose the left lung as noted in &#8220;Mouse Pneumonectomy&#8221; protocol. Lift the rib cage with curved blunt forceps to allow air into the left chest cavity (Figure 5A,B).</li>
	<li>Place a 24 G angiocatheter into the left thoracic cavity as above being careful not to injure the left lung.</li>
	<li>Using 5-0 prolene suture and being careful not to puncture the lung (Figure 5C), place two lengths of suture material into the 3rd/4th and 5th/6th rib interspaces (Figure 5D). Place both lengths of suture material before tying to lessen the risks of left lung herniation. Tie the suture material to make two interrupted stitches (Figure 5E).</li>
	<li>Glue the skin over the thoracic incision, remove residual air with the angiocatheter, and glue the neck incision as above.</li>
</ol>
6. Resuscitation, Analgesia, and Recovery
<ol>
	<li>Turn off the isoflurane, and administer 0.1 mg/kg of buprenorphine and 0.5 ml of normal saline subcutaneously.</li>
	<li>When spontaneous respirations resume, remove the endotracheal tube.</li>
	<li>Observe mouse until it is again ambulatory. Walking typically resumes several minutes after removal of the endotracheal tube.</li>
	<li>Place the mouse in a 27 &#176;C incubator (humidified, 25% oxygen) to recover O/N. 
	NOTE: We place several pellets of chow wetted with water on the cage floor for the first 24 hr after surgery.</li>
	<li>Administer 0.1 mg/kg of buprenorphine by intraperitoneal injection twice daily for three days after surgery. Take care not to open the surgical site when handling animals.</li>
</ol>
7. Mouse Monitoring
<ol>
	<li>Weigh mice at 1, 3, 5, and 7 days after surgery.</li>
</ol>

<ol>
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The authors have nothing to disclose.

We have provided the most detailed description of the mouse PNX and mouse sham PNX procedures reported to date. We have made the reader aware of several of the common pitfalls that investigators learning the procedure commonly encounter, and we have outlined several techniques developed by our laboratory to mitigate against these pitfalls. Other laboratories utilizing this model may have developed other technique modifications or use different instruments. When evaluating differences in techniques, individual investigato...

The principal function of the lung is to provide for oxygen and carbon dioxide exchange between an organism and the atmosphere. In humans, a host of congenital and acquired conditions lead to reduced lung surface area which results in impaired lung function. Although a host of therapies such as inhaled corticosteroids, bronchodilators, supplemental oxygen, and chronic mechanical ventilation are used to mitigate the consequences of impaired lung function1-3, the ideal therapy for these conditions would promote regrowth of functional lung tissue &#8211; i.e., lung regeneration.
Mammalian tissue regeneration has been well documented. The African Spiny Mouse can regenerate large areas of skin without scar formation4. The distal phalanx in humans can regenerate following injury or amputation5-7. Following pneumonectomy (PNX), compensatory lung growth occurs in mice8, rats9, dogs10, and humans11. By definition, compensatory lung growth involves not only expansion of existing airspaces, but re-septation of these enlarged airspaces with expansion of the associated microcirculation12. Gene expression analysis has demonstrated that this model recapitulates many of the signaling events of lung development13. Four weeks after mouse PNX, alveolar surface area is equivalent to that of sham operated animals14. In this manuscript, we describe the mouse PNX and sham PNX procedures.

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			<td style="width:263px;">Company</td>
			<td style="width:263px;">Catalogue number</td>
			<td style="width:263px;">Comments (optional)</td>
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			<td height="101" style="height:101px;width:263px;">6-inch Vascular Clip Applicator</td>
			<td style="width:263px;">Teleflex Medical (WECK)</td>
			<td style="width:263px;">137062</td>
			<td style="width:263px;"></td>
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		<tr height="101">
			<td height="101" style="height:101px;width:263px;">Horizon Small Titanium Red Clip</td>
			<td style="width:263px;">Teleflex Medical (WECK)</td>
			<td style="width:263px;">1201</td>
			<td style="width:263px;"></td>
		</tr>
		<tr height="121">
			<td height="121" style="height:121px;width:263px;">Narrow Pattern 12cm Curved Forceps</td>
			<td style="width:263px;">Fine Science Tools</td>
			<td style="width:263px;">11003-12</td>
			<td style="width:263px;"></td>
		</tr>
		<tr height="141">
			<td height="141" style="height:141px;width:263px;">Curved Serated 10 cm Graefe Forceps&#160;</td>
			<td style="width:263px;">Fine Science Tools</td>
			<td style="width:263px;">11052-10</td>
			<td style="width:263px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">Castroviejo Needle Holder</td>
			<td style="width:263px;">Fine Science Tools</td>
			<td style="width:263px;">12565-14</td>
			<td style="width:263px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:263px;">Straight 9 cm Strabismus Scissors (Blunt Tip)</td>
			<td style="width:263px;">Fine Science Tools</td>
			<td style="width:263px;">14075-09</td>
			<td style="width:263px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:263px;">Straight 8.5 cm Hardened Fine Scissors</td>
			<td style="width:263px;">Fine Science Tools</td>
			<td style="width:263px;">14090-09</td>
			<td style="width:263px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:263px;">Straight, Blunt Tip Cohan-Vannas Spring Scissors</td>
			<td style="width:263px;">Fine Science Tools</td>
			<td style="width:263px;">15000-12</td>
			<td style="width:263px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">Skin Glue</td>
			<td style="width:263px;">Gluture</td>
			<td style="width:263px;">32046</td>
			<td style="width:263px;"></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:263px;">22 ga angiocatheter</td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">24 ga angiocatheter</td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
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			<td height="21" style="height:21px;width:263px;">3 mL luer lock syringe</td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">4 short retractors</td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">2 long retractors</td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:263px;">5-0 Prolene on curved cutting needle</td>
			<td style="width:263px;">Ethicon</td>
			<td style="width:263px;">8698G</td>
			<td style="width:263px;"></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:263px;">0.5 mL syringe on 27 ga needle</td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
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			<td height="21" style="height:21px;width:263px;">Normal Saline</td>
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			<td height="21" style="height:21px;width:263px;">Buprenorphine</td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
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			<td height="21" style="height:21px;width:263px;">Press-n-Seal Wrap</td>
			<td style="width:263px;">Glad Products Company</td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:263px;">12 inch X 12 inch cork board stack</td>
			<td style="width:263px;">Office Depot</td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
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			<td height="21" style="height:21px;width:263px;">70% Ethanol</td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
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			<td height="21" style="height:21px;width:263px;">Betadine</td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
			<td style="width:263px;"></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:263px;">Mouse Ventilator</td>
			<td style="width:263px;">Hugo Sachs Elektronnik&#160;</td>
			<td style="width:263px;">Minivent Type 845</td>
			<td style="width:263px;"></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:263px;">Isoflurane Vaporizer</td>
			<td style="width:263px;">OHMEDA</td>
			<td style="width:263px;">Excel 210 SE</td>
			<td style="width:263px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:263px;">artificial tear ointment</td>
			<td style="width:263px;">puralube</td>
			<td style="width:263px;">NDC: 17033-211-38</td>
			<td style="width:263px;"></td>
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mouse pneumonectomy model of compensatory lung growth

In humans, disrupted repair and remodeling of injured lung contributes to a host of acute and chronic lung disorders which may ultimately lead to disability or death. Injury-based animal models of lung repair and regeneration are limited by injury-specific responses making it difficult to differentiate changes related to the injury response and injury resolution from changes related to lung repair and lung regeneration. However, use of animal models to identify these repair and regeneration signaling pathways is critical to the development of new therapies aimed at improving pulmonary function following lung injury. The mouse pneumonectomy model utilizes compensatory lung growth to isolate those repair and regeneration signals in order to more clearly define mechanisms of alveolar re-septation. Here, we describe our technique for performing mouse pneumonectomy and sham pneumonectomy. This technique may be utilized in conjunction with lineage tracing or other transgenic mouse models to define molecular and cellular mechanism of lung repair and regeneration.

A plot of PNX and sham operated mouse weights is provided in Figure 6. In our hands, survival is consistently 95 - 100% for both PNX and sham pneumonectomy. For descriptions of how the right lung re-grows in this model and the expected time course, we refer the reader to manuscripts of Gibney et al.15 and Wang et al.14
Several common pitfalls must be avoided to successfully perform the mouse PNX and mouse sham pneumonectomy procedures.</...

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Mouse Pneumonectomy Model of Compensatory Lung Growth

Mouse pneumonectomy is a commonly employed model of compensatory lung growth. This procedure can be used in conjunction with lineage tracing or transgenic mouse models to elucidate underlying mechanisms.

In humans, disrupted repair and remodeling of injured lung contributes to a host of acute and chronic lung disorders which may ultimately lead to ...

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12.7K Views.  Cincinnati Children's Hospital Medical Center. Mouse pneumonectomy is a commonly employed model of compensatory lung growth. This procedure can be used in conjunction with lineage tracing or transgenic mouse models to elucidate underlying mechanisms.

Video: Mouse Pneumonectomy Model of Compensatory Lung Growth

A Simple Method of Mouse Lung Intubation

A simple procedure to intubate mice for pulmonary function measurements would have several advantages in longitudinal studies with limited numbers or expensive animal. One of the reasons that this is not done more routinely is that it is relatively difficult, despite there being several published studies that describe ways to achieve it. In this paper we demonstrate a procedure that eliminates one of the major hurdles associated with this intubation, that of visualizing the trachea during the entire time of intubation. The approach uses a 0.5 mm fiberoptic light source that serves as an introducer to direct the intubation cannula into the mouse trachea. We show that it is possible to use this procedure to measure lung mechanics in individual mice over a time course of at least several weeks. The technique can be set up with relatively little expense and expertise, and it can be routinely accomplished with relatively little training. This should make it possible for any laboratory to routinely carry out this intubation, thereby allowing longitudinal studies in individual mice, thereby minimizing the number of mice needed and increasing the statistical power by using each mouse as its own control.

This paper describes a striaghforward and efficient method of intubating mice for pulmonary function measurements or pulmonary instillation, that allows the mice to recover and be studied at later times. The procedure involves an inexpensive fiberoptic light source that directly illuminates the trachea.

A  simple procedure to intubate mice for pulmonary function measurements would  have several advantages in longitudinal studies with limited numbers or  ...

Diagnostic Ultrasound Imaging of Mouse Diaphragm Function

Function analysis of rodent respiratory skeletal muscles, particularly the diaphragm, is commonly performed by isolating muscle strips using invasive surgical procedures. Although this is an effective method of assessing in vitro diaphragm activity, it involves non-survival surgery. The application of non-invasive ultrasound imaging as an in vivo procedure is beneficial since it not only reduces the number of animals sacrificed, but is also suitable for monitoring disease progression in live mice. Thus, our ultrasound imaging method may likely assist in the development of novel therapies that alleviate muscle injury induced by various respiratory diseases. Particularly, in clinical diagnoses of obstructive lung diseases, ultrasound imaging has the potential to be used in conjunction with other standard tests to detect the early onset of diaphragm muscle fatigue. In the current protocol, we describe how to accurately evaluate diaphragm contractility in a mouse model using a diagnostic ultrasound imaging technique.

Diagnostic ultrasound imaging has proven to be effective in diagnosing various respiratory diseases in human and animal subjects. We demonstrate a comprehensive ultrasound protocol utilized by Dr. Zuo's lab to analyze diaphragm kinetics specifically in mouse models. This is also a non-invasive research technique which can provide quantitative information on mouse respiratory muscle function.

Function analysis of rodent respiratory skeletal muscles, particularly the diaphragm, is commonly performed by isolating muscle strips using invasive ...

A Murine Model of Myocardial Ischemia-reperfusion Injury through Ligation of the Left Anterior Descending Artery

Acute or chronic myocardial infarction (MI) are cardiovascular events resulting in high morbidity and mortality. Establishing the pathological mechanisms at work during MI and developing effective therapeutic approaches requires methodology to reproducibly simulate the clinical incidence and reflect the pathophysiological changes associated with MI. Here, we describe a surgical method to induce MI in mouse models that can be used for short-term ischemia-reperfusion (I/R) injury as well as permanent ligation. The major advantage of this method is to facilitate location of the left anterior descending artery (LAD) to allow for accurate ligation of this artery to induce ischemia in the left ventricle of the mouse heart. Accurate positioning of the ligature on the LAD increases reproducibility of infarct size and thus produces more reliable results. Greater precision in placement of the ligature will improve the standard surgical approaches to simulate MI in mice, thus reducing the number of experimental animals necessary for statistically relevant studies and improving our understanding of the mechanisms producing cardiac dysfunction following MI. This mouse model of MI is also useful for the preclinical testing of treatments targeting myocardial damage following MI.

We introduce a surgical method to induce experimental ischemia/reperfusion (I/R) injury to simulate myocardial infarction (MI) in mouse models that allows for more clarity in positioning of the ligation on the left anterior descending artery (LAD) to increase the reproducibility of MI experiments in mice.

Acute or chronic myocardial infarction (MI) are cardiovascular events resulting in high morbidity and mortality. Establishing the pathological mechanisms ...

Implantation of Fibrin Gel on Mouse Lung to Study Lung-specific Angiogenesis

Recent significant advances in stem cell research and bioengineering techniques have made great progress in utilizing biomaterials to regenerate and repair damage in simple tissues in the orthopedic and periodontal fields. However, attempts to regenerate the structures and functions of more complex three-dimensional (3D) organs such as lungs have not been very successful because the biological processes of organ regeneration have not been well explored. It is becoming clear that angiogenesis, the formation of new blood vessels, plays key roles in organ regeneration. Newly formed vasculatures not only deliver oxygen, nutrients and various cell components that are required for organ regeneration but also provide instructive signals to the regenerating local tissues. Therefore, to successfully regenerate lungs in an adult, it is necessary to recapitulate the lung-specific microenvironments in which angiogenesis drives regeneration of local lung tissues. Although conventional in vivo angiogenesis assays, such as subcutaneous implantation of extracellular matrix (ECM)-rich hydrogels (e.g., fibrin or collagen gels or Matrigel - ECM protein mixture secreted by Engelbreth-Holm-Swarm mouse sarcoma cells), are extensively utilized to explore the general mechanisms of angiogenesis, lung-specific angiogenesis has not been well characterized because methods for orthotopic implantation of biomaterials in the lung have not been well established. The goal of this protocol is to introduce a unique method to implant fibrin gel on the lung surface of living adult mouse, allowing for the successful recapitulation of host lung-derived angiogenesis inside the gel. This approach enables researchers to explore the mechanisms by which the lung-specific microenvironment controls angiogenesis and alveolar regeneration in both normal and pathological conditions. Since implanted biomaterials release and supply physical and chemical signals to adjacent lung tissues, implantation of these biomaterials on diseased lung can potentially normalize the adjacent diseased tissues, enabling researchers to develop new therapeutic approaches for various types of lung diseases.

Recapitulation of the organ-specific microenvironment, which stimulates local angiogenesis, is indispensable for successful regeneration of damaged tissues. This report demonstrates a novel method to implant fibrin gels on the lung surface of living mouse in order to explore how the lung-specific microenvironment modulates angiogenesis and alveolar regeneration in adult mouse.

Recent significant advances in stem cell research and bioengineering techniques have made great progress in utilizing biomaterials to regenerate and ...

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. As this technology expands and improves, the ability to potentially evaluate and improve the quality of substandard lungs prior to transplant is a critical need. In order to more rigorously evaluate these approaches, a reproducible animal model needs to be established that would allow for testing of improved techniques and management of the donated lungs as well as to the lung-transplant recipient. In addition, an EVLP animal model of associated pathologies, e.g., ventilation induced lung injury (VILI), would provide a novel method to evaluate treatments for these pathologies. Here, we describe the development of a rat EVLP lung program and refinements to this method that allow for a reproducible model for future expansion. We also describe the application of this EVLP system to model VILI in rat lungs. The goal is to provide the research community with key information and &#8220;pearls of wisdom&#8221;/techniques that arose from trial and error and are critical to establishing an EVLP system that is robust and reproducible.

Method of Isolated Ex Vivo Lung Perfusion in a Rat Model: Lessons Learned from Developing a Rat EVLP Program

Ex-Vivo Lung Perfusion (EVLP) has allowed lung transplantation in humans to become more readily available by enabling the ability to assess organs and expand the donor pool. Here, we describe the development of a rat EVLP program and refinements that allow for a reproducible model for future expansion.

The number of acceptable donor lungs available for lung transplantation is severely limited due to poor quality. Ex-Vivo Lung Perfusion (EVLP) has allowed ...

Real-time X-ray Imaging of Lung Fluid Volumes in Neonatal Mouse Lung

At birth, the lung undergoes a profound phenotypic switch from secretion to absorption, which allows for adaptation to breathing independently. Promoting and sustaining this phenotype is critically important in normal alveolar growth and gas exchange throughout life. Several in vitro studies have characterized the role of key regulatory proteins, signaling molecules, and steroid hormones that can influence the rate of lung fluid clearance. However, in vivo examinations must be performed to evaluate whether these regulatory factors play important physiological roles in regulating perinatal lung liquid absorption. As such, the utilization of real time X-ray imaging to determine perinatal lung fluid clearance, or pulmonary edema, represents a technological advancement in the field. Herein, we explain and illustrate an approach to assess the rate of alveolar lung fluid clearance and alveolar flooding in C57BL/6 mice at post natal day 10 using X-ray imaging and analysis. Successful implementation of this protocol requires prior approval from institutional animal care and use committees (IACUC), an in vivo small animal X-ray imaging system, and compatible molecular imaging software.

We present a protocol to assess the rate of alveolar fluid clearance or pulmonary edema in neonatal mouse lung using X-ray imaging technology.

At birth, the lung undergoes a profound phenotypic switch from secretion to absorption, which allows for adaptation to breathing independently. Promoting ...

Apical Resection Mouse Model to Study Early Mammalian Heart Regeneration

Cardiovascular disease plagues the whole world due to intensive lifestyle changes. Heart regeneration holds great promise for repairing and restoring cardiomyocytes lost due to injury and disease. In contrast to the robust cardiac regeneration of certain lower vertebrates, adult mammalian hearts typically show minimal capacity for heart regeneration and repair. However, recent studies have sparked considerable scientific interest with the finding that, between postnatal day 1 to 7 (P1 to P7), the neonatal mouse heart retains significant regenerative potential after apical resection (i.e., surgical amputation and exposure of left ventricular apex). One major controversy over this finding might be due to the diverse surgery-related procedures used in efforts to replicate or expand upon this important finding. These instructions dynamically present the materials and methodology for apical resection in a mouse model. The salient steps of this rodent survival surgery involve hypothermia anesthesia, thoracotomy, surgical amputation of heart ventricular apex, and suture and recovery of mice. The approach described could expand the application of the apical resection mouse model for cardiovascular research.

A step-by-step video protocol of apical resection is demonstrated in this study. Apical resection is a recently highlighted surgical approach in mammalian heart regeneration research. This study may promote the application of apical resection as a standard methodology in research into the mechanism underlying heart regeneration.

Cardiovascular disease plagues the whole world due to intensive lifestyle changes. Heart regeneration holds great promise for repairing and restoring ...

Open Tracheostomy Gastric Acid Aspiration Murine Model of Acute Lung Injury Results in Maximal Acute Nonlethal Lung Injury

Acid pneumonitis is a major cause of sterile acute lung injury (ALI) in humans. Acid pneumonitis spans the clinical spectrum from asymptomatic to acute respiratory distress syndrome (ARDS), characterized by neutrophilic alveolitis, and injury to both alveolar epithelium and vascular endothelium. Clinically, ARDS is defined by acute onset of hypoxemia, bilateral patchy pulmonary infiltrates and non-cardiogenic pulmonary edema. Human studies have provided us with valuable information about the physiological and inflammatory changes in the lung caused by ARDS, which has led to various hypotheses about the underling mechanisms. Unfortunately, difficulties determining the etiology of ARDS, as well as a wide range of pathophysiology have resulted in a lack of critical information that could be useful in developing therapeutic strategies.
Translational animal models are valuable when their pathogenesis and pathophysiology accurately reproduce a concept proven in both in vitro and clinical settings. Although large animal models (e.g., sheep) share characteristics of the anatomy of human trachea-bronchial tree, murine models provide a host of other advantages including: low cost; short reproductive cycle lending itself to greater data acquisition; a well understood immunologic system; and a well characterized genome leading to the availability of a variety of gene deletion and transgenic strains. A robust model of low pH induced ARDS requires a murine ALI that targets mainly the alveolar epithelium, secondarily the vascular endothelium, as well as the small airways leading to the alveoli. Furthermore, a reproducible injury with wide differences between different injurious and non-injurious insults is important.
The murine gastric acid aspiration model presented here using hydrochloric acid employs an open tracheostomy and recreates a pathogenic scenario that reproduces the low pH pneumonitis injury in humans. Additionally, this model can be used to examine interaction of a low pH insult with other pulmonary injurious entities (e.g., food particles, pathogenic bacteria).

This protocol induces acute lung injury in a mouse that has close fidelity to the pathogenesis of acid pneumonitis observed in humans. We generate a maximal acute nonlethal low pH lung injury and account for differences in rodent-human anatomic respiratory structure using an open tracheostomy coupled with circumferential pressure release.

Acid pneumonitis is a major cause of sterile acute lung injury (ALI) in humans. Acid pneumonitis spans the clinical spectrum from asymptomatic to acute ...

Integrated Compensatory Responses in a Human Model of Hemorrhage

Hemorrhage is the leading cause of trauma-related deaths, partly because early diagnosis of the severity of blood loss is difficult. Assessment of hemorrhaging patients is difficult because current clinical tools provide measures of vital signs that remain stable during the early stages of bleeding due to compensatory mechanisms. Consequently, there is a need to understand and measure the total integration of mechanisms that compensate for reduced circulating blood volume and how they change during ongoing progressive hemorrhage. The body&#39;s reserve to compensate for reduced circulating blood volume is called the &#39;compensatory reserve&#39;. The compensatory reserve can be accurately evaluated with real-time measurements of changes in the features of the arterial waveform measured with the use of a high-powered computer. Lower Body Negative Pressure (LBNP) has been shown to simulate many of the physiological responses in humans associated with hemorrhage, and is used to study the compensatory response to hemorrhage. The purpose of this study is to demonstrate how compensatory reserve is assessed during progressive reductions in central blood volume with LBNP as a simulation of hemorrhage.

The purpose of this protocol is to demonstrate the techniques for measuring compensatory responses to reduced central blood volume using lower body negative pressure as a noninvasive experimental model of human hemorrhage which can be used to quantify the total integration of compensatory mechanisms to blood volume deficit in humans.

Hemorrhage is the leading cause of trauma-related deaths, partly because early diagnosis of the severity of blood loss is difficult. Assessment of ...

Echocardiographic Measurement of Right Ventricular Diastolic Parameters in Mouse

Diastolic dysfunction is a prominent feature of right ventricular (RV) remodeling associated with conditions of pressure overload. However, the RV diastolic function is rarely quantified in experimental studies. This might be due to technical difficulties in the visualization of the RV in the apical four-chamber view in rodents. Here we describe two positions facilitating the visualization of the apical four-chamber view in mice to assess the RV diastolic function.
The apical four-chamber view is enabled by tilting the mouse fixation platform to the left and caudally (LeCa) or to the right and cranially (RiCr). Both positions provide images of comparable quality. The results of the RV diastolic function obtained from two positions are not significantly different. Both positions are comparably easy to perform. This protocol can be incorporated into published protocols and enables detailed investigations of the RV function.

Here we describe and compare two positions for obtaining the apical four-chamber view in mice. These positions enable the quantification of the right ventricular function, provide comparable results, and can be used interchangeably.