Name: comprehensive echocardiographic assessment of right ventricle function in a rat model of pulmonary arterial hypertension
Uploaded: 2023-01-20T13:45:00
Description: Watch this Scientific Journal Video about Comprehensive Echocardiographic Assessment of Right Ventricle Function in a Rat Model of Pulmonary Arterial Hypertension at JoVE.com

This work was supported by NHLBI K01 HL155241 and AHA CDA849387 awarded to the author P.C.R.

All experiments in this protocol were performed following the animal care guidelines of the University of Illinois at Chicago, Chicago Institutional Animal Care and Use Committee. Male Sprague Dawley (SD) rats weighed between 0.200-0.240 kg at the time of MCT injection; however, the protocol described in this article can be used with a wider body weight range. The animals were obtained from a commercial source (see Table of Materials).
1. Study design
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	<li>Galie, N., McLaughlin, V. V., Rubin, L. J., Simonneau, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+overview+of+the+6th+World+Symposium+on+Pulmonary+Hypertension.">An overview of the 6th World Symposium on Pulmonary Hypertension.</a> European Respiratory Journal. 53 (1), 1802148 (2019).</li><li>Tyagi, S., Batra, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+therapeutic+approaches+of+pulmonary+arterial+hypertension.">Novel therapeutic approaches of pulmonary arterial hypertension.</a> International Journal of Angiology. 28 (2), 112-117 (2019).</li><li>Hoeper, M. 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W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Five-year+outcomes+of+patients+enrolled+in+the+REVEAL+registry.">Five-year outcomes of patients enrolled in the REVEAL registry.</a> Chest. 148 (4), 1043-1054 (2015).</li><li>Zolty, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+experimental+therapies+for+treatment+of+pulmonary+arterial+hypertension.">Novel experimental therapies for treatment of pulmonary arterial hypertension.</a> Journal of Experimental Pharmacology. 13, 817-857 (2021).</li><li>Jasmin, J. F., Lucas, M., Cernacek, P., Dupuis, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effectiveness+of+a+nonselective+ET(A/B)+and+a+selective+ET(A)+antagonist+in+rats+with+monocrotaline-induced+pulmonary+hypertension.">Effectiveness of a nonselective ET(A/B) and a selective ET(A) antagonist in rats with monocrotaline-induced pulmonary hypertension.</a> Circulation. 103 (2), 314-318 (2001).</li><li>Stenmark, K. R., Meyrick, B., Galie, N., Mooi, W. J., McMurtry, I. 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G., 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=Guidelines+for+the+echocardiographic+assessment+of+the+right+heart+in+adults:+a+report+from+the+American+Society+of+Echocardiography+endorsed+by+the+European+Association+of+Echocardiography,+a+registered+branch+of+the+European+Society+of+Cardiology,+and+the+Canadian+Society+of+Echocardiography.">Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography.</a> Journal of the American Society of Echocardiography. 23 (7), 685-713 (2010).</li><li>Jones, N., Burns, A. T., Prior, 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=Echocardiographic+assessment+of+the+right+ventricle-state+of+the+art.">Echocardiographic assessment of the right ventricle-state of the art.</a> Heart Lung and Circulation. 28 (9), 1339-1350 (2019).</li><li>Spyropoulos, 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=Echocardiographic+markers+of+pulmonary+hemodynamics+and+right+ventricular+hypertrophy+in+rat+models+of+pulmonary+hypertension.">Echocardiographic markers of pulmonary hemodynamics and right ventricular hypertrophy in rat models of pulmonary hypertension.</a> Pulmonary Circulation. 10 (2), 2045894020910976 (2020).</li><li>Armstrong, W. F., Ryan, T., Feigenbaum, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Feigenbaum's echocardiography. 7th edn. , (2010).</li><li>Kimura, 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=Evaluation+of+right+ventricle+by+speckle+tracking+and+conventional+echocardiography+in+rats+with+right+ventricular+heart+failure.">Evaluation of right ventricle by speckle tracking and conventional echocardiography in rats with right ventricular heart failure.</a> International Heart Journal. 56 (3), 349-353 (2015).</li><li>Cheng, H. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+right+ventricular+structure+and+function+in+mouse+model+of+pulmonary+artery+constriction+by+transthoracic+echocardiography.">Assessment of right ventricular structure and function in mouse model of pulmonary artery constriction by transthoracic echocardiography.</a> Journal of Visualized Experiments. 84, e51041 (2014).</li><li>Mazurek, J. A., Vaidya, A., Mathai, S. C., Roberts, J. D., Forfia, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Follow-up+tricuspid+annular+plane+systolic+excursion+predicts+survival+in+pulmonary+arterial+hypertension.">Follow-up tricuspid annular plane systolic excursion predicts survival in pulmonary arterial hypertension.</a> Pulmonary Circulation. 7 (2), 361-371 (2017).</li><li>Grapsa, 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=Echocardiographic+and+hemodynamic+predictors+of+survival+in+precapillary+pulmonary+hypertension:+seven-year+follow-up.">Echocardiographic and hemodynamic predictors of survival in precapillary pulmonary hypertension: seven-year follow-up.</a> Circulation: Cardiovascular Imaging. 8 (6), 002107 (2015).</li><li>Bernardo, I., Wong, J., Wlodek, M. E., Vlahos, R., Soeding, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+right+heart+function+in+a+rat+model+using+modified+echocardiographic+views.">Evaluation of right heart function in a rat model using modified echocardiographic views.</a> PLoS One. 12 (10), 0187345 (2017).</li></ol>

Echocardiographic evaluation of the RV is a valuable discovery tool for the screening of the effectiveness of novel treatments in animal models of PAH. In-depth characterization of the RV structure and function is necessary as novel targets in treating PAH address RV remodeling4,14. This study describes a detailed protocol that allows for the successful characterization of RV structure and function.
The complex structural geometry and ...

PAH is a progressive disease defined as a mean pulmonary arterial pressure at rest of greater than 20 mmHg1. Pathological changes in PAH include pulmonary artery (PA) remodeling, vasoconstriction, inflammation, and fibroblast activation and proliferation. These pathological changes lead to increased pulmonary vascular resistance and, consequently, right ventricular remodeling, hypertrophy, and failure2. PAH is a complex disease that involves crosstalk between several signaling pathways. The currently approved drugs for treating PAH mostly target vasodilator pathways, including the nitric oxide-cyclic guanosine monophosphate pathway, prostacyclin pathway, and endothelin pathway. Therapeutics targeting these pathways have been used as both monotherapies and in combination therapies3,4. Despite the advances in treatment for PAH in the last decade, findings from the US-based REVEAL registry show a poor 5 year survival rate for newly diagnosed patients5. More recently, emerging therapeutic modalities have focused on disease-modifying agents that can impact the multifactorial pathophysiology of the vascular remodeling occurring in PAH in the hope of disrupting the disease6.
Animal models of PAH are invaluable tools in assessing the efficacy of new drug treatments. The MCT-induced PAH rat model is a widely used animal model characterized by remodeling of the pulmonary arterial vessels, which in turn leads to increased pulmonary vascular resistance and right ventricular hypertrophy and dysfunction7,8. To assess the efficacy of new treatments, researchers normally focus on the terminal assessment of RV pressure without considering the longitudinal evaluation of PA pressure, RV morphology, and RV function. The use of noninvasive and non-terminal imaging techniques is crucial for a comprehensive examination of disease progression in animal models. Transthoracic echocardiography remains the standard approach to evaluating heart morphology and function in animal models due to its low cost and ease of use compared to other imaging modalities, such as magnetic resonance imaging. However, echocardiographic evaluation of the RV can be challenging due to the RV positioning beneath the sternum shadow, its well-developed trabeculation, and its anatomical shape, all of which make it difficult to delineate the endocardial border9,10,11.
This article aims to describe a comprehensive protocol to evaluate RV dimensions, areas and volumes, and systolic and diastolic function in naive and MCT-induced PAH in Sprague Dawley (SD) rats. Additionally, this protocol details a method to assess echocardiographic dimensions in the normal and dilated right atrium.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.9% sodium cloride injection USP</td>
			<td>Baxter</td>
			<td>2B1324</td>
			<td></td>
		</tr>
		<tr>
			<td>Braided cotton rolls</td>
			<td>4MD Medical Solutions</td>
			<td>RIHD201205</td>
			<td></td>
		</tr>
		<tr>
			<td>Depilating agent</td>
			<td>Wallgreens</td>
			<td>Nair Hair Remover&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Electrode gel</td>
			<td>Parker Laboratories&#160;</td>
			<td>15-60</td>
			<td></td>
		</tr>
		<tr>
			<td>High frequency ultrasound image system and imaging station</td>
			<td>FUJIFILM VisualSonics, Inc.</td>
			<td>Vevo 2100</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>MedVet</td>
			<td>RXISO-250</td>
			<td></td>
		</tr>
		<tr>
			<td>Male sprague Dawley rats</td>
			<td>Charles River Laboratories</td>
			<td>CD 001</td>
			<td>CD IGS Rats (Crl:CD(SD))</td>
		</tr>
		<tr>
			<td>Monocrotaline (MCT)</td>
			<td>Sigma-Aldrich</td>
			<td>C2401</td>
			<td></td>
		</tr>
		<tr>
			<td>Rectal temperature probe &#160;</td>
			<td>Physitemp&#160;</td>
			<td>RET-3</td>
			<td></td>
		</tr>
		<tr>
			<td>Sealed induction chambers</td>
			<td>Scivena Scientific</td>
			<td>RES644&#160;</td>
			<td>3 L size</td>
		</tr>
		<tr>
			<td>Solid-state array ultrasound transducer</td>
			<td>FUJIFILM VisualSonics, Inc.</td>
			<td>Vevo MicroScan transducer MS250S</td>
			<td></td>
		</tr>
		<tr>
			<td>Stainless steel digital calipers</td>
			<td>VWR Digital Calipers</td>
			<td>62379-531</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasound gel&#160;</td>
			<td>Parker Laboratories&#160;</td>
			<td>11-08</td>
			<td></td>
		</tr>
		<tr>
			<td>Vevo Lab software</td>
			<td>FUJIFILM VisualSonics, Inc.</td>
			<td></td>
			<td>Verison 5.5.1</td>
		</tr>
	</tbody>
</table>

comprehensive echocardiographic assessment of right ventricle function in a rat model of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease caused by vasoconstriction and remodeling of the small arteries in the lungs. This remodeling leads to increased pulmonary vascular resistance, worsened right ventricular function, and premature death. Currently approved therapies for PAH largely target pulmonary vasodilator pathways; however, recent emerging therapeutic modalities are focused on other novel pathways involved in the pathogenesis of the disease, including right ventricle (RV) remodeling. Imaging techniques that allow longitudinal assessment of novel therapeutics are very useful for determining the efficacy of new drugs in preclinical studies. Noninvasive trans-thoracic echocardiography remains the standard approach to evaluating heart function and is widely used in rodent models. However, echocardiographic evaluation of the RV can be challenging due to its anatomical position and structure. In addition, standardized guidelines are lacking for echocardiography&#160;in preclinical rodent models, making it difficult to carry out a uniform assessment of RV&#160;function across studies in different laboratories. In preclinical studies, the monocrotaline (MCT) injury model in rats is widely used to evaluate drug efficacy for treating PAH. This protocol describes the echocardiographic evaluation of the RV in na&#239;ve and MCT-induced PAH rats.

In this study, MCT-treated rats were used as a model of PAH. Echocardiographic analysis was performed on Study Day 23 post-MCT administration, and all measurements and calculations represented averages from three consecutive cycles. Echocardiographic parameters obtained from control (vehicle: deionized water) and MCT-treated (60 mg/kg) rats are shown in Table 1.
Representative images of the PLAX view in control and MCT-treated rats are shown in Figure 1A</...

Watch this Scientific Journal Video about Comprehensive Echocardiographic Assessment of Right Ventricle Function in a Rat Model of Pulmonary Arterial Hypertension at JoVE.com

Comprehensive Echocardiographic Assessment of Right Ventricle Function in a Rat Model of Pulmonary Arterial Hypertension

The present protocol describes the echocardiographic characterization of right ventricular morphology and function in a rat model of pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a progressive disease caused by vasoconstriction and remodeling of the small arteries in the lungs. This ...

In depth echocardiographic evaluation of the right ventricular structure and function is a valuable tool to screen the effectiveness of novel therapeutic targets in animal models of pulmonary hypertension. The main advantage of this protocol is that it provides a detailed description of all the echocardiographic views and measurements needed to assess the right atria and right ventricular morphology, as well as to characterize the right ventricle systolic and diastolic functions. This technique describes the echocardiographic characterization of a rat model of pulmonary hypertension induced by Monocrotaline.It is important that the echocardiographer spends enough time practicing and becoming proficient in the right ventricle imaging even if they had previous experience with the left ventricle. Begin by removing the rats from the induction chamber after they lose consciousness and transfer them to the imaging station animal platform in a dorsal decubitus position. Administer isoflurane using a nose cone connected to a vaporizer.Apply electrode gel to each paw and secure the paws in the electrocardiogram lead plates of the animal platform. Remove the fur by shaving the chest and using a depilating agent. Secure a rectal temperature probe in place.Place cotton rolls on the right and left side of the animal and secure them with tape to maintain the position when the platform is tilted. To acquire images, tilt the platform to the right by 10 to 15 degrees and bring it caudally down approximately five degrees. Move the transducer to point to the right parasternal line of the rat, and lower the transducer.Rotate the transducer counterclockwise to ensure the aorta and mitral valve are visible. Place the M-mode sample volume line at the region where the right ventricle is widest and adjust the gate to encompass the right and left ventricle. Lift the transducer and reposition it such that it is slightly inclined toward the right parasternal line of the rat.Move the platform to a position that is slightly tilted to the right. Lower the transducer until it is in contact with the gel. Move the platform caudally into the right or left until the right ventricular outflow track is in view and the pulmonary valve is in focus and clearly visible.Then press Sign Store to record the B-Mode image of the pulmonary artery valve. Maintaining the same B-Mode image location, press Color to aid the identification of flow through the pulmonary valve. Adjust the velocity so that the highest velocity point is visible.Press PW or Pulsed Wave to quantify the blood flow spectrum. Align the PW angle parallel to the direction of the flow through the pulmonary valve. Press update to view the pulmonary velocities.Tilt the platform to the left corner and down cranially as far as possible. Rotate the transducer counterclockwise by 30 to 45 degrees and move the transducer to point at the right shoulder or ear of the animal. Lower the transducer until it is in contact with the gel.Ensure a typical four chamber view where the left ventricle and left atria are visible, but the sternum shadow is over the right ventricle free wall. Move the transducer for adjusting the applicable four chamber view acquiring a focused view of the right ventricle. Move the platform slightly caudally if required until the maximal plane is obtained.Ensure that the right ventricle is not foreshortened and that the left ventricle outflow tract is not opened. Place the M-mode cursor through the tricuspid annulus at the right ventricular free wall to visualize TAPSE and press Update and Sign Store to record the TAPSE data. Press B-mode and then press Color to aid the identification of flow through the TV.Press PW to quantify the blood flow spectrum.Return to B-mode, press tissue, and place the Tissue Doppler sample volume gate at the tricuspid annulus at the RV free wall. Press Update to view the Tissue Doppler image. Using PLAX views, initial assessment of the position of the heart and left ventricular morphology was performed.Assessment of the right ventricle using a modified PLAX view showed that the monocrotaline or MCT-treated rats had an enlarged right ventricle and displaced left ventricle compared to the control rats. A significant increase in RVIDd, RVIDs, and RVFWT was observed in the MCT-treated rats indicating dilation of the right ventricle and thickening of the right ventricular free wall. The modified PLAX view was also used to visualize the pulmonary artery and measure the pulmonary valve diameter.Measurement of pulmonary artery flow velocities using doppler imaging showed that in control rats, pulmonary flow exhibited a symmetrical V shape with a peak velocity in mid-systole. Whereas an MCT-treated rats, peak velocity was slower and occurred earlier in the systole and displayed a notch in late systole. The right ventricle-focused apical four chamber view was used to measure right ventricular and systolic area and right atrial area.MCT-treated rats exhibited right atrial dilation because of increased pulmonary artery pressure. Moreover, the right ventricular pressure was increased resulting in loss of normal curvature of the left ventricle compared to controls. The intraventricular septum also appeared flattened.The bright ventricle-focused apical four chamber view was also used to measure TAPSE from the M-mode interrogation of the tricuspid annulus. TAPSE was significantly reduced in MCT-treated rats suggesting compromised function. The most challenging part of this protocol is obtaining an optimal right ventricle-focused apical four chamber view.We suggest that the echocardiographer ensures that the entire right ventricle is in the view during systole and diastole. Images are obtained with a right ventricle-focused apical four chamber view can be later used for a strain analysis, a powerful tool that may be used to evaluate right ventricle systolic dysfunction at the initial stages.

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Laser-Induced Chronic Ocular Hypertension Model on SD Rats

Glaucoma is one of the major causes of blindness in the world. Elevated intraocular pressure is a major risk factor. Laser photocoagulation induced ocular hypertension is one of the well established animal models. This video demonstrates how to induce ocular hypertension by Argon laser photocoagulation in rat.

Glaucoma is one of the major causes of blindness in the world. Elevated intraocular pressure is a major risk factor. Laser photocoagulation induced ocular hypertension is one of the well established animal models. This video demonstrates how to induce ocular hypertension by Argon laser photocoagulation in rat.

Glaucoma is one of the major causes of blindness in the world. Elevated intraocular pressure is a major risk factor. Laser photocoagulation induced ocular ...

Right Hemihepatectomy by Suprahilar Intrahepatic Transection of the Right Hemipedicle using a Vascular Stapler

Successful hepatic resection requires profound anatomical knowledge and delicate surgical technique. Hemihepatectomies are mostly performed after preparing the extrahepatic hilar structures within the hepatoduodenal ligament, even in benign tumours or liver metastasis.1-5. Regional extrahepatic lymphadenectomy is an oncological standard in hilar cholangiocarcinoma, intrahepatic cholangio-cellular carcinoma and hepatocellular carcinoma, whereas lymph node metastases in the hepatic hilus in patients with liver metastasis are rarely occult. Major disadvantages of these procedures are the complex preparation of the hilus with the risk of injuring contralateral structures and the possibility of bleeding from portal vein side-branches or impaired perfusion of bile ducts. We developed a technique of right hemihepatectomy or resection of the left lateral segments with intrahepatic transection of the pedicle that leaves the hepatoduodenal ligament completely untouched. 6 However, if intraoperative visualization or palpation of the ligament is suspicious for tumor infiltration or lymph node metastasis, the hilus should be explored and a lymphadenectomy performed.

This video describes a right hemihepatectomy with intrahepatic transection of the right hemipedicle leaving the hepatoduodenal ligament completely untouched.

Successful hepatic resection requires profound anatomical knowledge and delicate surgical technique. Hemihepatectomies are mostly performed after ...

A High-throughput Method for Measurement of Glomerular Filtration Rate in Conscious Mice

The measurement of glomerular filtration rate (GFR) is the gold standard in kidney function assessment. Currently, investigators determine GFR by measuring the level of the endogenous biomarker creatinine or exogenously applied radioactive labeled inulin (3H or 14C). Creatinine has the substantial drawback that proximal tubular secretion accounts for ~50% of total renal creatinine excretion and therefore creatinine is not a reliable GFR marker. Depending on the experiment performed, inulin clearance can be determined by an intravenous single bolus injection or continuous infusion (intravenous or osmotic minipump). Both approaches require the collection of plasma or plasma and urine, respectively. Other drawbacks of radioactive labeled inulin include usage of isotopes, time consuming surgical preparation of the animals, and the requirement of a terminal experiment. Here we describe a method which uses a single bolus injection of fluorescein isothiocyanate-(FITC) labeled inulin and the measurement of its fluorescence in 1-2 &mu;l of diluted plasma. By applying a two-compartment model, with 8 blood collections per mouse, it is possible to measure GFR in up to 24 mice per day using a special work-flow protocol. This method only requires brief isoflurane anesthesia with all the blood samples being collected in a non-restrained and awake mouse. Another advantage is that it is possible to follow mice over a period of several months and treatments (i.e. doing paired experiments with dietary changes or drug applications). We hope that this technique of measuring GFR is useful to other investigators studying mouse kidney function and will replace less accurate methods of estimating kidney function, such as plasma creatinine and blood urea nitrogen.

Measurement of glomerular filtration rate (GFR) is the gold standard for kidney function assessment. Here we describe a high-throughput method which allows the determination of GFR in conscious mice by using a single bolus injection, determination of fluorescein isothiocyanate (FITC)-inulin in plasma and calculation of GFR by a two-phase exponential decay model.

The measurement of  glomerular filtration rate (GFR) is the gold standard in kidney function  assessment. Currently, investigators determine GFR by ...

Phenotyping Mouse Pulmonary Function In Vivo with the Lung Diffusing Capacity

The mouse is now the primary animal used to model a variety of lung diseases. To study the mechanisms that underlie such pathologies, phenotypic methods are needed that can quantify the pathologic changes. Furthermore, to provide translational relevance to the mouse models, such measurements should be tests that can easily be done in both humans and mice. Unfortunately, in the present literature few phenotypic measurements of lung function have direct application to humans. One exception is the diffusing capacity for carbon monoxide, which is a measurement that is routinely done in humans. In the present report, we describe a means to quickly and simply measure this diffusing capacity in mice. The procedure involves brief lung inflation with tracer gases in an anesthetized mouse, followed by a 1 min gas analysis time. We have tested the ability of this method to detect several lung pathologies, including emphysema, fibrosis, acute lung injury, and influenza and fungal lung infections, as well as monitoring lung maturation in young pups. Results show significant decreases in all the lung pathologies, as well as an increase in the diffusing capacity with lung maturation. This measurement of lung diffusing capacity thus provides a pulmonary function test that has broad application with its ability to detect phenotypic structural changes with most of the existing pathologic lung models.

Phenotyping Mouse Pulmonary Function In Vivo with the Lung Diffusing Capacity

We describe a means to quickly and simply measure the lung diffusing capacity in mice and show that it is sufficiently sensitive to phenotype changes in multiple common lung pathologies. This metric thus brings direct translational relevance to the mouse models, since diffusing capacity is also easily measured in humans.

The mouse is now the primary animal used to model a variety of lung diseases. To study the mechanisms that underlie such pathologies, phenotypic methods ...

Functional Reconstitution and Channel Activity Measurements of Purified Wildtype and Mutant CFTR Protein

The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a unique channel-forming member of the ATP Binding Cassette (ABC) superfamily of transporters. The phosphorylation and nucleotide dependent chloride channel activity of CFTR has been frequently studied in whole cell systems and as single channels in excised membrane patches. Many Cystic Fibrosis-causing mutations have been shown to alter this activity. While a small number of purification protocols have been published, a fast reconstitution method that retains channel activity and a suitable method for studying population channel activity in a purified system have been lacking. Here rapid methods are described for purification and functional reconstitution of the full-length CFTR protein into proteoliposomes of defined lipid composition that retains activity as a regulated halide channel. This reconstitution method together with a novel flux-based assay of channel activity is a suitable system for studying the population channel properties of wild type CFTR and the disease-causing mutants F508del- and G551D-CFTR. Specifically, the method has utility in studying the direct effects of phosphorylation, nucleotides and small molecules such as potentiators and inhibitors on CFTR channel activity. The methods are also amenable to the study of other membrane channels/transporters for anionic substrates.

Described here is a rapid and effective procedure for functional reconstitution of purified wild-type and mutant CFTR protein that preserves activity for this chloride channel, which is defective in Cystic Fibrosis. Iodide efflux from reconstituted proteoliposomes mediated by CFTR allows studies of channel activity and the effects of small molecules.

The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a unique channel-forming member of the ATP Binding Cassette (ABC) superfamily of ...

Inducible LAP-tagged Stable Cell Lines for Investigating Protein Function, Spatiotemporal Localization and Protein Interaction Networks

Multi-protein complexes, rather than single proteins acting in isolation, often govern molecular pathways regulating cellular homeostasis. Based on this principle, the purification of critical proteins required for the functioning of these pathways along with their native interacting partners has not only allowed the mapping of the protein constituents of these pathways, but has also provided a deeper understanding of how these proteins coordinate to regulate these pathways. Within this context, understanding a protein's spatiotemporal localization and its protein-protein interaction network can aid in defining its role within a pathway, as well as how its misregulation may lead to disease pathogenesis. To address this need, several approaches for protein purification such as tandem affinity purification (TAP) and localization and affinity purification (LAP) have been designed and used successfully. Nevertheless, in order to apply these approaches to pathway-scale proteomic analyses, these strategies must be supplemented with modern technological developments in cloning and mammalian stable cell line generation. Here, we describe a method for generating LAP-tagged human inducible stable cell lines for investigating protein subcellular localization and protein-protein interaction networks. This approach has been successfully applied to the dissection of multiple cellular pathways including cell division and is compatible with high-throughput proteomic analyses.

We describe a method for generating localization and affinity purification (LAP)-tagged inducible stable cell lines for investigating protein function, spatiotemporal subcellular localization and protein-protein interaction networks.

Multi-protein complexes, rather than single proteins acting in isolation, often govern molecular pathways regulating cellular homeostasis. Based on this ...

A Rapid Automated Protocol for Muscle Fiber Population Analysis in Rat Muscle Cross Sections Using Myosin Heavy Chain Immunohistochemistry

Quantification of muscle fiber populations provides a deeper insight into the effects of disease, trauma, and various other influences on skeletal muscle composition. Various time-consuming methods have traditionally been used to study fiber populations in many fields of research. However, recently developed immunohistochemical methods based on myosin heavy chain protein expression provide a quick alternative to identify multiple fiber types in a single section. Here, we present a rapid, reliable and reproducible protocol for improved staining quality, allowing automatic acquisition of whole cross sections and automatic quantification of fiber populations with ImageJ. For this purpose, embedded skeletal muscles are cut in cross sections, stained using myosin heavy chains antibodies with secondary fluorescent antibodies and DAPI for cell nuclei staining. Whole cross sections are then scanned automatically using a slide scanner to obtain high-resolution composite pictures of the entire specimen. Fiber population analyses are subsequently performed to quantify slow, intermediate and fast fibers using an automated macro for ImageJ. We have previously shown that this method can identify fiber populations reliably to a degree of &#177;4%. In addition, this method reduces inter-user variability and time per analyses significantly using the open source platform ImageJ.

Here, we present a protocol for rapid muscle fiber analyses, which allows improved staining quality, and thereby automatic acquisition and quantification of fiber populations using the freely available software ImageJ.

Quantification of muscle fiber populations provides a deeper insight into the effects of disease, trauma, and various other influences on skeletal muscle ...

A Protocol for Using Gene Set Enrichment Analysis to Identify the Appropriate Animal Model for Translational Research

Recent studies that compared transcriptomic datasets of human diseases with datasets from mouse models using traditional gene-to-gene comparison techniques resulted in contradictory conclusions regarding the relevance of animal models for translational research. A major reason for the discrepancies between different gene expression analyses is the arbitrary filtering of differentially expressed genes. Furthermore, the comparison of single genes between different species and platforms often is limited by technical variance, leading to misinterpretation of the con/discordance between data from human and animal models. Thus, standardized approaches for systematic data analysis are needed. To overcome subjective gene filtering and ineffective gene-to-gene comparisons, we recently demonstrated that gene set enrichment analysis (GSEA) has the potential to avoid these problems. Therefore, we developed a standardized protocol for the use of GSEA to distinguish between appropriate and inappropriate animal models for translational research. This protocol is not suitable to predict how to design new model systems a-priori, as it requires existing experimental omics data. However, the protocol describes how to interpret existing data in a standardized manner in order to select the most suitable animal model, thus avoiding unnecessary animal experiments and misleading translational studies.

We provide a standardized protocol for the use of gene set enrichment analysis of transcriptomic data to identify an ideal mouse model for translational research. 
This protocol can be used with DNA microarray and RNA sequencing data and can further be extended to other omics data if data are available.

Recent studies that compared transcriptomic datasets of human diseases with datasets from mouse models using traditional gene-to-gene comparison ...

Implantation of Electrospun Vascular Grafts with Optimized Structure in a Rat Model

Here, we present a protocol to fabricate macroporous PCL vascular graft and describe an evaluation protocol by using a rat model of abdominal aorta replacement. The electrospun vascular grafts often possess relatively small pores, which limit cell infiltration into the grafts and hinder the regeneration and remodeling of the neo-arteries. In this study, PCL vascular grafts with thicker fibers (5 - 6 &#181;m) and larger pores (~30 &#181;m) were fabricated by using a modified processing technique. The long-term performance of the graft was evaluated by implantation in a rat abdominal aorta model. Ultrasound analysis showed that the grafts remained patent without aneurysm or stenosis occurring even after 12 months of implantation. Macroporous structure improved the cell ingrowth and thus promoted tissue regenerated at 3 months. More importantly, there was no sign of adverse remodeling, such as calcification within the graft wall after 12 months. Therefore, electrospun PCL vascular grafts with modified macroporous processing hold potential to be an artery substitute for long-term implantation.

Here, we present a modified electrospinning method to fabricate PCL vascular grafts with thick fibers and large pores, and describe a protocol to evaluate the in vivo performance in a rat model of abdominal aorta replacement.

Here, we present a protocol to fabricate macroporous PCL vascular graft and describe an evaluation protocol by using a rat model of abdominal aorta ...

Induction of Right Ventricular Failure by Pulmonary Artery Constriction and Evaluation of Right Ventricular Function in Mice

The mechanism of right ventricular failure (RVF) requires clarification due to the uniqueness, high morbidity, high mortality, and refractory nature of RVF. Previous rat models imitating RVF progression have been described. Compared with rats, mice are more accessible, economical, and widely used in animal experiments. We developed a pulmonary artery constriction (PAC) approach which is comprised of banding the pulmonary trunk in mice to induce right ventricular (RV) hypertrophy. A special surgical latch needle was designed that allows for easier separation of the aorta and the pulmonary trunk. In our experiments, the use of this fabricated latch needle reduced the risk of arteriorrhexis and improved the surgical success rate to 90%. We used different padding needle diameters to precisely create quantitative constriction, which can induce different degrees of RV hypertrophy. We quantified the degree of constriction by evaluating the blood flow velocity of the PA, which was measured by noninvasive transthoracic echocardiography. RV function was precisely evaluated by right heart catheterization at 8 weeks after surgery. The surgical instruments made inhouse were composed of common materials using a simple process that is easy to master. Therefore, the PAC approach described here is easy to imitate using instruments made in the lab and can be widely used in other labs. This study presents a modified PAC approach that has a higher success rate than other models and an 8-week postsurgery survival rate of 97.8%. This PAC approach provides a useful technique for studying the mechanism of RVF and will enable an increased understanding of RVF.

Here, we provide a useful approach for studying the mechanism of right ventricular failure. A more convenient and efficient approach to pulmonary artery constriction is established using surgical instruments made inhouse. In addition, methods to evaluate the quality of this approach by echocardiography and catheterization are provided.

The mechanism of right ventricular failure (RVF) requires clarification due to the uniqueness, high morbidity, high mortality, and refractory nature of ...